Долгих Дмитрий Александрович

Доктор биологических наук


Руководитель подразделения (Лаборатория инженерии белка)

Тел.: +7 (495) 336-80-11

Эл. почта: dolgikh@nmr.ru

Избранные публикации

  1. Feldman T.B., Smitienko O.A., Shelaev I.V., Gostev F.E., Nekrasova O.V., Dolgikh D.A., Nadtochenko V.A., Kirpichnikov M.P., Ostrovsky M.A. (2016). Femtosecond spectroscopic study of photochromic reactions of bacteriorhodopsin and visual rhodopsin. J. Photochem. Photobiol. B, Biol. 164, 296–305 [+]

    Photochromic ultrafast reactions of bacteriorhodopsin (H. salinarum) and bovine rhodopsin were conducted with a femtosecond two-pump probe pulse setup with the time resolution of 20-25fs. The dynamics of the forward and reverse photochemical reactions for both retinal-containing proteins was compared. It is demonstrated that when retinal-containing proteins are excited by femtosecond pulses, dynamics pattern of the vibrational coherent wave packets in the course of the reaction is different for bacteriorhodopsin and visual rhodopsin. As shown in these studies, the low-frequencies that form a wave packets experimentally observed in the dynamics of primary products formation as a result of retinal photoisomerization have different intensities and are clearer for bovine rhodopsin. Photo-reversible reactions for both retinal proteins were performed from the stage of the relatively stable photointermediates that appear within 3-5ps after the light pulse impact. It is demonstrated that the efficiency of the reverse phototransition K-form→bacteriorhodopsin is almost five-fold higher than that of the Batho-intermediate→visual rhodopsin phototransition. The results obtained indicate that in the course of evolution the intramolecular mechanism of the chromophore-protein interaction in visual rhodopsin becomes more perfect and specific. The decrease in the probability of the reverse chromophore photoisomerization (all-trans→11-cis retinal) in primary photo-induced rhodopsin products causes an increase in the efficiency of the photoreception process.

    ID:1612
  2. Siletsky S.A., Mamedov M.D., Lukashev E.P., Balashov S.P., Dolgikh D.A., Rubin A.B., Kirpichnikov M.P., Petrovskaya L.E. (2016). Electrogenic steps of light-driven proton transport in ESR, a retinal protein from Exiguobacterium sibiricum. Biochim. Biophys. Acta 1857 (11), 1741–1750 [+]

    A retinal protein from Exiguobacterium sibiricum (ESR) functions as a light-driven proton pump. Unlike other proton pumps, it contains Lys96 instead of a usual carboxylic residue in the internal proton donor site. Nevertheless, the reprotonation of the Schiff base occurs fast, indicating that Lys96 facilitates proton transfer from the bulk. In this study we examined kinetics of light-induced transmembrane electrical potential difference, ΔΨ, generated in proteoliposomes reconstituted with ESR. We show that total magnitude of ΔΨ is comparable to that produced by bacteriorhodopsin but its kinetic components and their pH dependence are substantially different. The results are in agreement with the earlier finding that proton uptake precedes reprotonation of the Schiff base in ESR, suggesting that Lys96 is unprotonated in the initial state and gains a proton transiently in the photocycle. The electrogenic phases and the photocycle transitions related to proton transfer from the bulk to the Schiff base are pH dependent. At neutral pH, they occur with τ 0.5ms and 4.5ms. At alkaline pH, the fast component ceases and Schiff base reprotonation slows. At pH8.4, a spectrally silent electrogenic component with τ 0.25ms is detected, which can be attributed to proton transfer from the bulk to Lys96. At pH5.1, the amplitude of ΔΨ decreases 10 fold, reflecting a decreased yield and rate of proton transfer, apparently from protonation of the acceptor (Asp85-His57 pair) in the initial state. The features of the photoelectric potential generation correlate with the ESR structure and proposed mechanism of proton transfer.

    ID:1662
  3. Shulepko M.A., Lyukmanova E.N., Shenkarev Z.O., Dubovskii P.V., Astapova M.V., Feofanov A.V., Arseniev A.S., Utkin Y.N., Kirpichnikov M.P., Dolgikh D.A. (2016). Towards universal approach for bacterial production of three-finger Ly6/uPAR proteins: Case study of cytotoxin I from cobra N. oxiana. Protein Expr. Purif. 130, 13–20 [+]

    Cytotoxins or cardiotoxins is a group of polycationic toxins from cobra venom belonging to the 'three-finger' protein superfamily (Ly6/uPAR family) which includes small β-structural proteins (60-90 residues) with high disulfide bond content (4-5 disulfides). Due to a high cytotoxic activity for cancer cells, cytotoxins are considered as potential anticancer agents. Development of the high-throughput production methods is required for the prospective applications of cytotoxins. Here, efficient approach for bacterial production of recombinant analogue of cytotoxin I from N. oxiana containing additional N-terminal Met-residue (rCTX1) was developed. rCTX1 was produced in the form of E. coli inclusion bodies. Refolding in optimized conditions provided ∼6 mg of correctly folded protein from 1 L of bacterial culture. Cytotoxicity of rCTX1 for C6 rat glioma cells was found to be similar to the activity of wild type CTX1. The milligram quantities of (13)C,(15)N-labeled rCTX1 were obtained. NMR study confirmed the similarity of the spatial structures of recombinant and wild-type toxins. Additional Met residue does not perturb the overall structure of the three-finger core. The analysis of available data for different Ly6/uPAR proteins of snake and human origin revealed that efficiency of their folding in vitro is correlated with the number of proline residues in the third loop and the surface area of hydrophobic residues buried within the protein interior. The obtained data indicate that hydrophobic core is important for the folding of proteins with high disulfide bond content. Developed expression method opens new possibilities for structure-function studies of CTX1 and other related three-finger proteins.

    ID:1599
  4. Thomsen M.S., Arvaniti M., Jensen M.M., Shulepko M.A., Dolgikh D.A., Pinborg L.H., Härtig W., Lyukmanova E.N., Mikkelsen J.D. (2016). Lynx1 and Aβ1-42 bind competitively to multiple nicotinic acetylcholine receptor subtypes. Neurobiol. Aging 46, 13–21 [+]

    Lynx1 regulates synaptic plasticity in the brain by regulating nicotinic acetylcholine receptors (nAChRs). It is not known to which extent Lynx1 can bind to endogenous nAChR subunits in the brain or how this interaction is affected by Alzheimer's disease pathology. We apply affinity purification to demonstrate that a water-soluble variant of human Lynx1 (Ws-Lynx1) isolates α3, α4, α5, α6, α7, β2, and β4 nAChR subunits from human and rat cortical extracts, and rat midbrain and olfactory bulb extracts, suggesting that Lynx1 forms complexes with multiple nAChR subtypes in the human and rodent brain. Incubation with Ws-Lynx1 decreases nicotine-mediated extracellular signal-regulated kinase phosphorylation in PC12 cells and striatal neurons, indicating that binding of Ws-Lynx1 is sufficient to inhibit signaling downstream of nAChRs. The effect of nicotine in PC12 cells is independent of α7 or α4β2 nAChRs, suggesting that Lynx1 can affect the function of native non-α7, non-α4β2 nAChR subtypes. We further show that Lynx1 and oligomeric β-amyloid1-42 compete for binding to several nAChR subunits, that Ws-Lynx1 prevents β-amyloid1-42-induced cytotoxicity in cortical neurons, and that cortical Lynx1 levels are decreased in a transgenic mouse model with concomitant β-amyloid and tau pathology. Our data suggest that Lynx1 binds to multiple nAChR subtypes in the brain and that this interaction might have functional and pathophysiological implications in relation to Alzheimer's disease.

    ID:1667
  5. Lyukmanova E.N., Shulepko M.A., Shenkarev Z.O., Kasheverov I.E., Chugunov A.O., Kulbatskii D.S., Myshkin M.Y., Utkin Y.N., Efremov R.G., Tsetlin V.I., Arseniev A.S., Kirpichnikov M.P., Dolgikh D.A. (2016). Central loop of non-conventional toxin WTX from Naja kaouthia is important for interaction with nicotinic acetylcholine receptors. Toxicon 119, 274–9 [+]

    'Three-finger' toxin WTX from Naja kaouthia interacts with nicotinic and muscarinic acetylcholine receptors (nAChRs and mAChRs). Mutagenesis and competition experiments with (125)I-α-bungarotoxin revealed that Arg31 and Arg32 residues from the WTX loop II are important for binding to Torpedo californica and human α7 nAChRs. Computer modeling suggested that loop II occupies the orthosteric binding site at α7 nAChR. The similar toxin interface was previously described as a major determinant of allosteric interactions with mAChRs.

    ID:1598
  6. Lyukmanova E.N., Shulepko M.A., Shenkarev Z.O., Bychkov M.L., Paramonov A.S., Chugunov A.O., Kulbatskii D.S., Arvaniti M., Dolejsi E., Schaer T., Arseniev A.S., Efremov R.G., Thomsen M.S., Dolezal V., Bertrand D., Dolgikh D.A., Kirpichnikov M.P. (2016). Secreted Isoform of Human Lynx1 (SLURP-2): Spatial Structure and Pharmacology of Interactions with Different Types of Acetylcholine Receptors. Sci Rep 6, 30698 [+]

    Human-secreted Ly-6/uPAR-related protein-2 (SLURP-2) regulates the growth and differentiation of epithelial cells. Previously, the auto/paracrine activity of SLURP-2 was considered to be mediated via its interaction with the α3β2 subtype of the nicotinic acetylcholine receptors (nAChRs). Here, we describe the structure and pharmacology of a recombinant analogue of SLURP-2. Nuclear magnetic resonance spectroscopy revealed a 'three-finger' fold of SLURP-2 with a conserved β-structural core and three protruding loops. Affinity purification using cortical extracts revealed that SLURP-2 could interact with the α3, α4, α5, α7, β2, and β4 nAChR subunits, revealing its broader pharmacological profile. SLURP-2 inhibits acetylcholine-evoked currents at α4β2 and α3β2-nAChRs (IC50 ~0.17 and >3 μM, respectively) expressed in Xenopus oocytes. In contrast, at α7-nAChRs, SLURP-2 significantly enhances acetylcholine-evoked currents at concentrations <1 μM but induces inhibition at higher concentrations. SLURP-2 allosterically interacts with human M1 and M3 muscarinic acetylcholine receptors (mAChRs) that are overexpressed in CHO cells. SLURP-2 was found to promote the proliferation of human oral keratinocytes via interactions with α3β2-nAChRs, while it inhibited cell growth via α7-nAChRs. SLURP-2/mAChRs interactions are also probably involved in the control of keratinocyte growth. Computer modeling revealed possible SLURP-2 binding to the 'classical' orthosteric agonist/antagonist binding sites at α7 and α3β2-nAChRs.

    ID:1597
  7. Lyukmanova E.N., Shulepko M.A., Kudryavtsev D., Bychkov M.L., Kulbatskii D.S., Kasheverov I.E., Astapova M.V., Feofanov A.V., Thomsen M.S., Mikkelsen J.D., Shenkarev Z.O., Tsetlin V.I., Dolgikh D.A., Kirpichnikov M.P. (2016). Human Secreted Ly-6/uPAR Related Protein-1 (SLURP-1) Is a Selective Allosteric Antagonist of α7 Nicotinic Acetylcholine Receptor. PLoS ONE 11 (2), e0149733 [+]

    SLURP-1 is a secreted toxin-like Ly-6/uPAR protein found in epithelium, sensory neurons and immune cells. Point mutations in the slurp-1 gene cause the autosomal inflammation skin disease Mal de Meleda. SLURP-1 is considered an autocrine/paracrine hormone that regulates growth and differentiation of keratinocytes and controls inflammation and malignant cell transformation. The majority of previous studies of SLURP-1 have been made using fusion constructs containing, in addition to the native protein, extra polypeptide sequences. Here we describe the activity and pharmacological profile of a recombinant analogue of human SLURP-1 (rSLURP-1) differing from the native protein only by one additional N-terminal Met residue. rSLURP-1 significantly inhibited proliferation (up to ~ 40%, EC50 ~ 4 nM) of human oral keratinocytes (Het-1A cells). Application of mecamylamine and atropine,-non-selective inhibitors of nicotinic acetylcholine receptors (nAChRs) and muscarinic acetylcholine receptors, respectively, and anti-α7-nAChRs antibodies revealed α7 type nAChRs as an rSLURP-1 target in keratinocytes. Using affinity purification from human cortical extracts, we confirmed that rSLURP-1 binds selectively to the α7-nAChRs. Exposure of Xenopus oocytes expressing α7-nAChRs to rSLURP-1 caused a significant non-competitive inhibition of the response to acetylcholine (up to ~ 70%, IC50 ~ 1 μM). It was shown that rSLURP-1 binds to α7-nAChRs overexpressed in GH4Cl cells, but does not compete with 125I-α-bungarotoxin for binding to the receptor. These findings imply an allosteric antagonist-like mode of SLURP-1 interaction with α7-nAChRs outside the classical ligand-binding site. Contrary to rSLURP-1, other inhibitors of α7-nAChRs (mecamylamine, α-bungarotoxin and Lynx1) did not suppress the proliferation of keratinocytes. Moreover, the co-application of α-bungarotoxin with rSLURP-1 did not influence antiproliferative activity of the latter. This supports the hypothesis that the antiproliferative activity of SLURP-1 is related to 'metabotropic' signaling pathway through α7-nAChR, that activates intracellular signaling cascades without opening the receptor channel.

    ID:1420
  8. Dolgikh D.A., Malyshev A.Y., Salozhin S.V., Nekrasova O.V., Petrovskaya L.E., Roshchin M.V., Borodinova A.A., Feldman T.B., Balaban P.M., Kirpichnikov M.P., Ostrovsky M.A. (2015). Anion-selective channelrhodopsin expressed in neuronal cell culture and in vivo in murine brain: Light-induced inhibition of generation of action potentials. Dokl. Biochem. Biophys. 465 (1), 424–7 [+]

    Anionic channelrhodopsin slow ChloC was expressed in the culture of nerve cells and in vivo in mouse brain. We demonstrated ability of slow ChloC to suppress effectively the activity of the neuron in response to the illumination with the visible light. It has been shown for a first time that slow ChloC works equally efficiently in both neuronal culture and in the whole brain being expressed in vivo. Thus, slow ChloC could be considered as an effective optogenetic tool capable in response to light stimulation to inhibit the generation of action potentials in the neuron.

    ID:1478
  9. Lyukmanova E.N., Shenkarev Z.O., Shulepko M.A., Paramonov A.S., Chugunov A.O., Janickova H., Dolejsi E., Dolezal V., Utkin Y.N., Tsetlin V.I., Arseniev A.S., Efremov R.G., Dolgikh D.A., Kirpichnikov M.P. (2015). Structural Insight into Specificity of Interactions between Nonconventional Three-finger Weak Toxin from Naja kaouthia (WTX) and Muscarinic Acetylcholine Receptors. J. Biol. Chem. 290 (39), 23616–30 [+]

    Weak toxin from Naja kaouthia (WTX) belongs to the group of nonconventional "three-finger" snake neurotoxins. It irreversibly inhibits nicotinic acetylcholine receptors and allosterically interacts with muscarinic acetylcholine receptors (mAChRs). Using site-directed mutagenesis, NMR spectroscopy, and computer modeling, we investigated the recombinant mutant WTX analogue (rWTX) which, compared with the native toxin, has an additional N-terminal methionine residue. In comparison with the wild-type toxin, rWTX demonstrated an altered pharmacological profile, decreased binding of orthosteric antagonist N-methylscopolamine to human M1- and M2-mAChRs, and increased antagonist binding to M3-mAChR. Positively charged arginine residues located in the flexible loop II were found to be crucial for rWTX interactions with all types of mAChR. Computer modeling suggested that the rWTX loop II protrudes to the M1-mAChR allosteric ligand-binding site blocking the entrance to the orthosteric site. In contrast, toxin interacts with M3-mAChR by loop II without penetration into the allosteric site. Data obtained provide new structural insight into the target-specific allosteric regulation of mAChRs by "three-finger" snake neurotoxins.

    ID:1394
  10. Gasparian M.E., Bychkov M.L., Yagolovich A.V., Dolgikh D.A., Kirpichnikov M.P. (2015). Mutations Enhancing Selectivity of Antitumor Cytokine TRAIL to DR5 Receptor Increase Its Cytotoxicity against Tumor Cells. Biochemistry Mosc. 80 (8), 1080–91 [+]

    Tumor necrosis factor superfamily cytokine TRAIL (tumor necrosis factor-related apoptosis-inducing ligand) induces apoptosis in tumor cells by binding to death receptors DR4 and DR5 without affecting normal cells. However, the therapeutic use of TRAIL is limited, because many tumor cells are resistant to it. The resistance is partially related to interaction of TRAIL with the decoy receptors DcR1 and DcR2, which do not trigger the apoptotic signal and inhibit signaling of death receptors. Previously, we designed a unique DR5-specific TRAIL mutant variant DR5-B, which binds to DR5 receptor as effectively as the original cytokine, but has practically no interaction with DR4 and DcR1 receptors, and its affinity for DcR2 is reduced 400-fold. In the present work, the cytotoxity of TRAIL and DR5-B was analyzed on 12 different tumor cell lines and two types of normal cells. In nine of 12 tumor cell lines, DR5-B killed 1.5-5.0 times more tumor cells than TRAIL, and it did not exhibit toxicity towards normal cells. Chemotherapeutic drugs such as doxorubicin, paclitaxel, and bortezomib augmented the effect of both TRAIL variants, and the enhancing effect was more pronounced for DR5-B. Half-maximal effective concentrations (EC50) for DR5-B in combination with chemotherapeutic agents were 1.5-10.0 times lower than for wild-type TRAIL. Thus, DR5-B is a promising candidate both for monotherapy and in combination with chemotherapy for treatment of TRAIL-resistant tumors.

    ID:1482
  11. Kudryavtsev D.S., Shelukhina I.V., Son L.V., Ojomoko L.O., Kryukova E.V., Lyukmanova E.N., Zhmak M.N., Dolgikh D.A., Ivanov I.A., Kasheverov I.E., Starkov V.G., Ramerstorfer J., Sieghart W., Tsetlin V.I., Utkin Y.N. (2015). Neurotoxins from Snake Venoms and α-Conotoxin ImI Inhibit Functionally Active Ionotropic GABA Receptors. J. Biol. Chem. , [+]

    Ionotropic receptors of γ-aminobutyric acid (GABAAR) regulate neuronal inhibition and are targeted by benzodiazepines and general anesthetics. We show that a fluorescent derivative of α-cobratoxin (α-Ctx), belonging to the family of three-finger toxins (TFTs) from snake venoms, specifically stained the α1β3γ2 receptor; at 10 μM α-Ctx completely blocked GABA-induced currents in this receptor expressed in Xenopus oocytes (IC50 = 236 nM) and less potently inhibited α1β2γ2 ≈ α2β2γ2 > α5β2γ2 > α2β3γ2 and α1β3δ GABAARs. The α1β3γ2 receptor was also inhibited by some other TFTs: long α-neurotoxin Ls III and non-conventional toxin WTX. α-Conotoxin ImI displayed inhibitory activity as well. Electrophysiology experiments showed mixed competitive and non-competitive α-Ctx action. Fluorescent α-Ctx, however, could be displaced by muscimol indicating that most of the α-Ctx binding sites overlap with the orthosteric sites at the β/α subunit interface. Modeling and molecular dynamic studies indicated that α-Ctx or α-bungarotoxin seem to interact with GABAAR in a way similar to their interaction with the acetylcholine-binding protein or the ligand-binding domain of nicotinic receptors. This was supported by mutagenesis studies and experiments with α-conotoxin ImI and a chimeric Naja oxiana α-neurotoxin indicating that the major role in α-Ctx binding to GABAAR is played by the tip of its central loop II accomodating under loop C of the receptors.

    ID:1307
  12. Bychkov M.L., Gasparian M.E., Dolgikh D.A., Kirpichnikov M.P. (2014). Combination of TRAIL with bortezomib shifted apoptotic signaling from DR4 to DR5 death receptor by selective internalization and degradation of DR4. PLoS ONE 9 (10), e109756 [+]

    TRAIL (tumor necrosis factor-related apoptosis-inducing ligand) mediates apoptosis in cancer cells through death receptors DR4 and DR5 preferring often one receptor over another in the cells expressing both receptors. Receptor selective mutant variants of TRAIL and agonistic antibodies against DR4 and DR5 are highly promising anticancer agents. Here using DR5 specific mutant variant of TRAIL - DR5-B we have demonstrated for the first time that the sensitivity of cancer cells can be shifted from one TRAIL death receptor to another during co-treatment with anticancer drugs. First we have studied the contribution of DR4 and DR5 in HCT116 p53+/+ and HCT116 p53−/− cells and demonstrated that in HCT116 p53+/+ cells the both death receptors are involved in TRAIL-induced cell death while in HCT116 p53−/− cells prevailed DR4 signaling. The expression of death (DR4 and DR5) as well as decoy (DcR1 and DcR2) receptors was upregulated in the both cell lines either by TRAIL or by bortezomib. However, combined treatment of cells with two drugs induced strong time-dependent and p53-independent internalization and further lysosomal degradation of DR4 receptor. Interestingly DR5-B variant of TRAIL which do not bind with DR4 receptor also induced elimination of DR4 from cell surface in combination with bortezomib indicating the ligand-independent mechanism of the receptor internalization. Eliminatory internalization of DR4 resulted in activation of DR5 receptor thus DR4-dependent HCT116 p53−/− cells became highly sensitive to DR5-B in time-dependent manner. Internalization and degradation of DR4 receptor depended on activation of caspases as well as of lysosomal activity as it was completely inhibited by Z-VAD-FMK, E-64 and Baf-A1. In light of our findings, it is important to explore carefully which of the death receptors is active, when sensitizing drugs are combined with agonistic antibodies to the death receptors or receptor selective variants of TRAIL to enhance cancer treatment efficiency.

    ID:1296
  13. Lyukmanova E.N., Shulepko M.A., Bychkov M.L., Shenkarev Z.O., Paramonov A.S., Chugunov A.O., Arseniev A.S., Dolgikh D.A., Kirpichnikov M.P. (2014). Human SLURP-1 and SLURP-2 Proteins Acting on Nicotinic Acetylcholine Receptors Reduce Proliferation of Human Colorectal Adenocarcinoma HT-29 Cells. Acta Naturae 6 (4), 60–6 [+]

    Human secreted Ly-6/uPAR related proteins (SLURP-1 and SLURP-2) are produced by various cells, including the epithelium and immune system. These proteins act as autocrine/paracrine hormones regulating the growth and differentiation of keratinocytes and are also involved in the control of inflammation and malignant cell transformation. These effects are assumed to be mediated by the interactions of SLURP-1 and SLURP-2 with the α7 and α3β2 subtypes of nicotinic acetylcholine receptors (nAChRs), respectively. Available knowledge about the molecular mechanism underling the SLURP-1 and SLURP-2 effects is very limited. SLURP-2 remains one of the most poorly studied proteins of the Ly-6/uPAR family. In this study, we designed for the first time a bacterial system for SLURP-2 expression and a protocol for refolding of the protein from cytoplasmic inclusion bodies. Milligram quantities of recombinant SLURP-2 and its 13C-15N-labeled analog were obtained. The recombinant protein was characterized by NMR spectroscopy, and a structural model was developed. A comparative study of the SLURP-1 and SLURP-2 effects on the epithelial cell growth was conducted using human colorectal adenocarcinoma HT-29 cells, which express only α7-nAChRs. A pronounced antiproliferative effect of both proteins was observed. Incubation of cells with 1 μM SLURP-1 and 1 μM SLURP-2 during 48 h led to a reduction in the cell number down to ~ 54 and 63% relative to the control, respectively. Fluorescent microscopy did not reveal either apoptotic or necrotic cell death. An analysis of the dose-response curve revealed the concentration-dependent mode of the SLURP-1 and SLURP-2 action with EC50 ~ 0.1 and 0.2 nM, respectively. These findings suggest that the α7-nAChR is the main receptor responsible for the antiproliferative effect of SLURP proteins in epithelial cells.

    ID:1256
  14. Balabashin D., Kovalenko E., Toporova V., Aliev T., Panina A., Svirshchevskaya E., Dolgikh D., Kirpichnikov M. (2014). Production of anti TNF-α antibodies in eukaryotic cells using different combinations of vectors carrying heavy and light chains. Cytotechnology , ID:1153
  15. Amdursky N., Ferber D., Bortolotti C.A., Dolgikh D.A., Chertkova R.V., Pecht I., Sheves M., Cahen D. (2014). Solid-state electron transport via cytochrome c depends on electronic coupling to electrodes and across the protein. Proc. Natl. Acad. Sci. U.S.A. 111 (15), 5556–61 [+]

    Electronic coupling to electrodes, Γ, as well as that across the examined molecules, H, is critical for solid-state electron transport (ETp) across proteins. Assessing the importance of each of these couplings helps to understand the mechanism of electron flow across molecules. We provide here experimental evidence for the importance of both couplings for solid-state ETp across the electron-mediating protein cytochrome c (CytC), measured in a monolayer configuration. Currents via CytC are temperature-independent between 30 and ∼130 K, consistent with tunneling by superexchange, and thermally activated at higher temperatures, ascribed to steady-state hopping. Covalent protein-electrode binding significantly increases Γ, as currents across CytC mutants, bound covalently to the electrode via a cysteine thiolate, are higher than those through electrostatically adsorbed CytC. Covalent binding also reduces the thermal activation energy, Ea, of the ETp by more than a factor of two. The importance of H was examined by using a series of seven CytC mutants with cysteine residues at different surface positions, yielding distinct electrode-protein(-heme) orientations and separation distances. We find that, in general, mutants with electrode-proximal heme have lower Ea values (from high-temperature data) and higher conductance at low temperatures (in the temperature-independent regime) than those with a distal heme. We conclude that ETp across these mutants depends on the distance between the heme group and the top or bottom electrode, rather than on the total separation distance between electrodes (protein width).

    ID:1664
  16. Gasparian M.E., Bobik T.V., Kim Y.V., Ponomarenko N.A., Dolgikh D.A., Gabibov A.G., Kirpichnikov M.P. (2013). Heterogeneous catalysis on the phage surface: Display of active human enteropeptidase. Biochimie 95 (11), 2076–81 [+]
    ID:924
  17. NovototskayaVlasova K., Petrovskaya L., Kryukova E., Rivkina E., Dolgikh D., Kirpichnikov M. (2013). Expression and chaperone-assisted refolding of a new cold-active lipase from Psychrobacter cryohalolentis K5(T). Protein Expr. Purif. 91 (1), 96–103 [+]
    ID:925
  18. Gushchin I., Chervakov P., Kuzmichev P., Popov A.N., Round E., Borshchevskiy V., Ishchenko A., Petrovskaya L., Chupin V., Dolgikh D.A., Arseniev A.S., Kirpichnikov M., Gordeliy V. (2013). Structural insights into the proton pumping by unusual proteorhodopsin from nonmarine bacteria. Proc. Natl. Acad. Sci. U.S.A. 110 (31), 12631–6 [+]

    Light-driven proton pumps are present in many organisms. Here, we present a high-resolution structure of a proteorhodopsin from a permafrost bacterium, Exiguobacterium sibiricum rhodopsin (ESR). Contrary to the proton pumps of known structure, ESR possesses three unique features. First, ESR's proton donor is a lysine side chain that is situated very close to the bulk solvent. Second, the α-helical structure in the middle of the helix F is replaced by 3(10)- and π-helix-like elements that are stabilized by the Trp-154 and Asn-224 side chains. This feature is characteristic for the proteorhodopsin family of proteins. Third, the proton release region is connected to the bulk solvent by a chain of water molecules already in the ground state. Despite these peculiarities, the positions of water molecule and amino acid side chains in the immediate Schiff base vicinity are very well conserved. These features make ESR a very unusual proton pump. The presented structure sheds light on the large family of proteorhodopsins, for which structural information was not available previously.

    ID:1260
  19. Balashov S.P., Petrovskaya L.E., Imasheva E.S., Lukashev E.P., Dioumaev A.K., Wang J.M., Sychev S.V., Dolgikh D.A., Rubin A.B., Kirpichnikov M.P., Lanyi J.K. (2013). Breaking the carboxyl rule: lysine 96 facilitates reprotonation of the Schiff base in the photocycle of a retinal protein from Exiguobacterium sibiricum. J. Biol. Chem. 288 (29), 21254–65 [+]
    ID:927
  20. Dioumaev A.K., Petrovskaya L.E., Wang J.M., Balashov S.P., Dolgikh D.A., Kirpichnikov M.P., Lanyi J.K. (2013). Photocycle of Exiguobacterium sibiricum rhodopsin characterized by low-temperature trapping in the IR and time-resolved studies in the visible. The journal of physical chemistry. B 117 (24), 7235–53 [+]
    ID:926
  21. Lyukmanova E.N., Shulepko M.A., Buldakova S.L., Kasheverov I.E., Shenkarev Z.O., Reshetnikov R.V., Filkin S.Y., Kudryavtsev D.S., Ojomoko L.O., Kryukova E.V., Dolgikh D.A., Kirpichnikov M.P., Bregestovski P.D., Tsetlin V.I. (2013). Water-soluble LYNX1 residues important for interaction with muscle-type and/or neuronal nicotinic receptors. J. Biol. Chem. 288 (22), 15888–99 [+]
    ID:929
  22. NovototskayaVlasova K.A., Petrovskaya L.E., Rivkina E.M., Dolgikh D.A., Kirpichnikov M.P. (2013). Characterization of a cold-active lipase from Psychrobacter cryohalolentis K5(T) and its deletion mutants. Biochemistry Mosc. 78 (4), 385–94 [+]
    ID:928
  23. Shulepko M.A., Lyukmanova E.N., Paramonov A.S., Lobas A.A., Shenkarev Z.O., Kasheverov I.E., Dolgikh D.A., Tsetlin V.I., Arseniev A.S., Kirpichnikov M.P. (2013). Human neuromodulator SLURP-1: bacterial expression, binding to muscle-type nicotinic acetylcholine receptor, secondary structure, and conformational heterogeneity in solution. Biochemistry Mosc. 78 (2), 204–11 [+]
    ID:930
  24. Lyukmanova E.N., Shenkarev Z.O., Khabibullina N.F., Kulbatskiy D.S., Shulepko M.A., Petrovskaya L.E., Arseniev A.S., Dolgikh D.A., Kirpichnikov M.P. (2012). N-terminal fusion tags for effective production of g-protein-coupled receptors in bacterial cell-free systems. Acta Naturae 4 (4), 58–64 [+]

    G-protein-coupled receptors (GPCR) constitute one of the biggest families of membrane proteins. In spite of the fact that they are highly relevant to pharmacy, they have remained poorly explored. One of the main bottlenecks encountered in structural-functional studies of GPCRs is the difficulty to produce sufficient amounts of the proteins. Cell-free systems based on bacterial extracts fromE. colicells attract much attention as an effective tool for recombinant production of membrane proteins. GPCR production in bacterial cell-free expression systems is often inefficient because of the problems associated with the low efficiency of the translation initiation process. This problem could be resolved if GPCRs were expressed in the form of hybrid proteins with N-terminal polypeptide fusion tags. In the present work, three new N-terminal fusion tags are proposed for cell-free production of the human β2-adrenergic receptor, human M1 muscarinic acetylcholine receptor, and human somatostatin receptor type 5. It is demonstrated that the application of an N-terminal fragment (6 a.a.) of bacteriorhodopsin fromExiguobacterium sibiricum(ESR-tag), N-terminal fragment (16 а.о.) of RNAse A (S-tag), and Mistic protein fromB. subtilisallows to increase the CF synthesis of the target GPCRs by 5-38 times, resulting in yields of 0.6-3.8 mg from 1 ml of the reaction mixture, which is sufficient for structural-functional studies.

    ID:801
  25. Balashov S.P., Petrovskaya L.E., Lukashev E.P., Imasheva E.S., Dioumaev A.K., Wang J.M., Sychev S.V., Dolgikh D.A., Rubin A.B., Kirpichnikov M.P., Lanyi J.K. (2012). Aspartate-histidine interaction in the retinal schiff base counterion of the light-driven proton pump of Exiguobacterium sibiricum. Biochemistry 51 (29), 5748–62 [+]
    ID:931
  26. Ostapchenko V.G., Gasparian M.E., Kosinsky Y.A., Efremov R.G., Dolgikh D.A., Kirpichnikov M.P. (2012). Dissecting structural basis of the unique substrate selectivity of human enteropeptidase catalytic subunit. J. Biomol. Struct. Dyn. 30 (1), 62–73 [+]

    Enteropeptidase is a key enzyme in the digestion system of higher animals. It initiates enzymatic cascade cleaving trypsinogen activation peptide after a unique sequence DDDDK. Recently, we have found specific activity of human enteropeptidase catalytic subunit (L-HEP) being significantly higher than that of its bovine ortholog (L-BEP). Moreover, we have discovered that L-HEP hydrolyzed several nonspecific peptidic substrates. In this work, we aimed to further characterize species-specific enteropeptidase activities and to reveal their structural basis. First, we compared hydrolysis of peptides and proteins lacking DDDDK sequence by L-HEP and L-BEP. In each case human enzyme was more efficient, with the highest hydrolysis rate observed for substrates with a large hydrophobic residue in P2-position. Computer modeling suggested enzyme exosite residues 96 (Arg in L-HEP, Lys in L-BEP) and 219 (Lys in L-HEP, Gln in L-BEP) to be responsible for these differences in enteropeptidase catalytic activity. Indeed, human-to-bovine mutations Arg96Lys, Lys219Gln shifted catalytic properties of L-HEP toward those of L-BEP. This effect was amplified in case of the double mutation Arg96Lys/Lys219Gln, but still did not cover the full difference in catalytic activities of human and bovine enzymes. To find a missing link, we studied monopeptide benzyl-arginine-β-naphthylamide hydrolysis. L-HEP catalyzed it with an order lower K (m) than L-BEP, suggesting the monopeptide-binding S1 site input into catalytic distinction between two enteropeptidase species. Together, our findings suggest structural basis of the unique catalytic properties of human enteropeptidase and instigate further studies of its tentative physiological and pathological roles.

    ID:809
  27. Lyukmanova E.N., Shenkarev Z.O., Khabibullina N.F., Kopeina G.S., Shulepko M.A., Paramonov A.S., Mineev K.S., Tikhonov R.V., Shingarova L.N., Petrovskaya L.E., Dolgikh D.A., Arseniev A.S., Kirpichnikov M.P. (2011). Lipid-protein nanodisks for cell-free production of integral membrane proteins in a soluble and folded state: Comparison with detergent micelles, bicelles and liposomes. Biochim. Biophys. Acta , [+]

    Production of integral membrane proteins (IMPs) in a folded state is a key prerequisite for their functional and structural studies. In cell-free (CF) expression systems membrane mimicking components could be added to the reaction mixture that promotes IMP production in a soluble form. Here lipid-protein nanodisks (LPNs) of different lipid compositions (DMPC, DMPG, POPC, POPC/DOPG) have been compared with classical membrane mimicking media such as detergent micelles, lipid/detergent bicelles and liposomes by their ability to support CF synthesis of IMPs in a folded and soluble state. Three model membrane proteins of different topology were used: homodimeric transmembrane (TM) domain of human receptor tyrosine kinase ErbB3 (TM-ErbB3, 1TM); voltage-sensing domain of K(+) channel KvAP (VSD, 4TM); and bacteriorhodopsin from Exiguobacterium sibiricum (ESR, 7TM). Structural and/or functional properties of the synthesized proteins were analyzed. LPNs significantly enhanced synthesis of the IMPs in a soluble form regardless of the lipid composition. A partial disintegration of LPNs composed of unsaturated lipids was observed upon co-translational IMP incorporation. Contrary to detergents the nanodisks resulted in the synthesis of ~80% active ESR and promoted correct folding of the TM-ErbB3. None of the tested membrane mimetics supported CF synthesis of correctly folded VSD, and the protocol of the domain refolding was developed. The use of LPNs appears to be the most promising approach to CF production of IMPs in a folded state. NMR analysis of (15)N-Ile-TM-ErbB3 co-translationally incorporated into LPNs shows the great prospects of this membrane mimetics for structural studies of IMPs produced by CF systems.

    ID:541
  28. Mineev K.S., Khabibullina N.F., Lyukmanova E.N., Dolgikh D.A., Kirpichnikov M.P., Arseniev A.S. (2011). Spatial structure and dimer-monomer equilibrium of the ErbB3 transmembrane domain in DPC micelles. Biochim. Biophys. Acta 1808 (8), 2081–8 [+]

    In present work the interaction of two TM α-helices of the ErbB3 receptor tyrosine kinase from the ErbB or HER family (residues 639-670) was studied by means of NMR spectroscopy in a membrane-mimicking environment provided by the DPC micelles. The ErbB3 TM segment appeared to form a parallel symmetric dimer in a left-handed orientation. The interaction between TM spans is accomplished via the non-standard motif and is supported by apolar contacts of bulky side chains and by stacking of aromatic rings together with π-cation interactions of Phe and Arg side chains. The investigation of the dimer-monomer equilibrium revealed thermodynamic properties of the assembly and the presence of two distinct regimes of the dimerization at low and at high peptide/detergent ratio. It was found that the detergent in case of ErbB3 behaves not as an ideal solvent, thus affecting the dimer-monomer equilibrium. Such behavior may account for the problems occurring with the refolding and stability of multispan helical membrane proteins in detergent solutions. The example of ErbB3 allows us to conclude that the thermodynamic parameters of dimerization, measured in micelles for two different helical pairs, cannot be compared without the investigation of their dependence on detergent concentration.

    ID:446
  29. Lyukmanova E.N., Shenkarev Z.O., Shulepko M.A., Mineev K.S., DHoedt D., Kasheverov I.E., Filkin S.Y., Krivolapova A.P., Janickova H., Dolezal V., Dolgikh D.A., Arseniev A.S., Bertrand D., Tsetlin V.I., Kirpichnikov M.P. (2011). NMR structure and action on nicotinic acetylcholine receptors of water-soluble domain of human LYNX1. J. Biol. Chem. 286 (12), 10618–27 [+]

    Discovery of proteins expressed in the central nervous system sharing the three-finger structure with snake α-neurotoxins provoked much interest to their role in brain functions. Prototoxin LYNX1, having homology both to Ly6 proteins and three-finger neurotoxins, is the first identified member of this family membrane-tethered by a GPI anchor, which considerably complicates in vitro studies. We report for the first time the NMR spatial structure for the water-soluble domain of human LYNX1 lacking a GPI anchor (ws-LYNX1) and its concentration-dependent activity on nicotinic acetylcholine receptors (nAChRs). At 5-30 μM, ws-LYNX1 competed with (125)I-α-bungarotoxin for binding to the acetylcholine-binding proteins (AChBPs) and to Torpedo nAChR. Exposure of Xenopus oocytes expressing α7 nAChRs to 1 μM ws-LYNX1 enhanced the response to acetylcholine, but no effect was detected on α4β2 and α3β2 nAChRs. Increasing ws-LYNX1 concentration to 10 μM caused a modest inhibition of these three nAChR subtypes. A common feature for ws-LYNX1 and LYNX1 is a decrease of nAChR sensitivity to high concentrations of acetylcholine. NMR and functional analysis both demonstrate that ws-LYNX1 is an appropriate model to shed light on the mechanism of LYNX1 action. Computer modeling, based on ws-LYNX1 NMR structure and AChBP x-ray structure, revealed a possible mode of ws-LYNX1 binding.

    ID:445
  30. Шулепко М.А., Люкманова Е.Н., Кашеверов И.Е., Долгих Д.А., Цетлин В.И., Кирпичников М.П. (2011). Бактериальная продукция водорастворимого домена lynx1, - эндогенного нейромодулятора никотиновых рецепторов человека. Биоорг. хим. 37 (5), ID:449
  31. Nekrasova O.V., Wulfson A.N., Tikhonov R.V., Yakimov S.A., Simonova T.N., Tagvey A.I., Dolgikh D.A., Ostrovsky M.A., Kirpichnikov M.P. (2010). A new hybrid protein for production of recombinant bacteriorhodopsin in Escherichia coli. J. Biotechnol. 147 (3-4), 145–50 [+]
    ID:933
  32. Samatova E.N., Melnik B.S., Balobanov V.A., Katina N.S., Dolgikh D.A., Semisotnov G.V., Finkelstein A.V., Bychkova V.E. (2010). Folding intermediate and folding nucleus for I--&gt;N and U--&gt;I--&gt;N transitions in apomyoglobin: contributions by conserved and nonconserved residues. Biophys. J. 98 (8), 1694–702 [+]
    ID:932
  33. Lesovoy D.M., Bocharov E.V., Lyukmanova E.N., Kosinsky Y.A., Shulepko M.A., Dolgikh D.A., Kirpichnikov M.P., Efremov R.G., Arseniev A.S. (2009). Specific membrane binding of neurotoxin II can facilitate its delivery to acetylcholine receptor. Biophys. J. 97 (7), 2089–97 [+]

    The action of three-finger snake alpha-neurotoxins at their targets, nicotinic acetylcholine receptors (nAChR), is widely studied because of its biological and pharmacological relevance. Most such studies deal only with ligands and receptor models; however, for many ligand/receptor systems the membrane environment may affect ligand binding. In this work we focused on binding of short-chain alpha-neurotoxin II (NTII) from Naja oxiana to the native-like lipid bilayer, and the possible role played by the membrane in delivering the toxin to nAChR. Experimental (NMR and mutagenesis) and molecular modeling (molecular-dynamics simulation) studies revealed a specific interaction of the toxin molecule with the phosphatidylserine headgroup of lipids, resulting in the proper topology of NTII on lipid bilayers favoring the attack of nAChR. Analysis of short-chain alpha-neurotoxins showed that most of them possess a high positive charge and sequence homology in the lipid-binding motif of NTII, implying that interaction with the membrane surrounding nAChR may be common for the toxin family.

    ID:319
  34. Lyukmanova E.N., Shulepko M.A., Tikhonov R.V., Shenkarev Z.O., Paramonov A.S., Wulfson A.N., Kasheverov I.E., Ustich T.L., Utkin Y.N., Arseniev A.S., Tsetlin V.I., Dolgikh D.A., Kirpichnikov M.P. (2009). Bacterial production and refolding from inclusion bodies of a "weak" toxin, a disulfide rich protein. Biochemistry Mosc. 74 (10), 1142–9 [+]

    The gene for the "weak" toxin of Naja kaouthia venom was expressed in Escherichia coli. "Weak" toxin is a specific inhibitor of nicotine acetylcholine receptor, but mechanisms of interaction of similar neurotoxins with receptors are still unknown. Systems previously elaborated for neurotoxin II from venom of the cobra Naja oxiana were tested for bacterial production of "weak" toxin from N. kaouthia venom. Constructs were designed for cytoplasmic production of N. kaouthia "weak" toxin in the form of a fused polypeptide chain with thioredoxin and for secretion with the leader peptide STII. However, it became possible to obtain "weak" toxin in milligram amounts only within cytoplasmic inclusion bodies. Different approaches for refolding of the toxin were tested, and conditions for optimization of the yield of the target protein during refolding were investigated. The resulting protein was characterized by mass spectrometry and CD and NMR spectroscopy. Experiments on competitive inhibition of (125)I-labeled alpha-bungarotoxin binding to the Torpedo californica electric organ membranes containing the muscle-type nicotine acetylcholine receptor (alpha1(2)beta1gammadelta) showed the presence of biological activity of the recombinant "weak" toxin close to the activity of the natural toxin (IC(50) = 4.3 +/- 0.3 and 3.0 +/- 0.5 microM, respectively). The interaction of the recombinant toxin with alpha7 type human neuronal acetylcholine receptor transfected in the GH(4)C(1) cell line also showed the presence of activity close to that of the natural toxin (IC(50) 31 +/- 5.0 and 14.8 +/- 1.3 microM, respectively). The developed bacterial system for production of N. kaouthia venom "weak" toxin was used to obtain (15)N-labeled analog of the neurotoxin.

    ID:352
  35. Samatova E.N., Katina N.S., Balobanov V.A., Melnik B.S., Dolgikh D.A., Bychkova V.E., Finkelstein A.V. (2009). How strong are side chain interactions in the folding intermediate? Protein Sci. 18 (10), 2152–9 [+]
    ID:935
  36. Gasparian M.E., Chernyak B.V., Dolgikh D.A., Yagolovich A.V., Popova E.N., Sycheva A.M., Moshkovskiĭ S.A., Kirpichnikov M.P. (2009). Generation of new TRAIL mutants DR5-A and DR5-B with improved selectivity to death receptor 5. Apoptosis 14 (6), 778–87 [+]
    ID:934
  37. Lyukmanova E.N., Shulepko M.A., Shenkarev Z.O., Dolgikh D.A., Kirpichnikov M.P. (2009). [The in vitro production of three-finger neurotoxins from snake venoms with a high abundance of disulfide bonds. Problems and their solutions]. Bioorg. Khim. 36 (2), 149–58 [+]

    alpha-Neurotoxins from snake venom are highly efficient inhibitors of nicotinic acetylcholine receptors (nAChR). These small proteins that have a beta-structural organization attract much interest as a tool for studies of nACh R and as prototypes for the development of new Pharmaceuticals for the treatment of diseases of the nervous system. However, the in vitro production of "three-finger" neurotoxins is complicated by the presence of four or five disulfide bonds that are closely located in their molecules. The present review contains a description of the most frequently used modern approaches for the E. coli expression of recombinant proteins (direct expression, expression as fusions, and secretion) with an emphasis placed on the recombinant production of snake alpha-neurotoxins. The methods of E. coli expression of isotopically labeled neurotoxins are described. The proposed solutions will be of broad interest for the bacterial production of other disulfide-abundant proteins.

    ID:349
  38. Liukmanova E.N., Shulga A.A., Arseneva D.A., Pluzhnikov K.A., Dolgikh D.A., Arsenev A.S., Kirpichnikov M.P. (2009). [Expression of neurotoxin II from Naja oxiana cobra venom in Escherichia coli in a hybrid form with thioredoxin]. Bioorg. Khim. 30 (1), 30–40 [+]

    Neurotoxin II from the venom of cobra Naja oxiana is a short type alpha-neurotoxin, which competitively inhibits nicotinic acetylcholine receptor. The toxin gene was expressed as a construct fused with the thioredoxin gene and the linker encoding the enteropeptidase recognition site and a Met residue between the genes. The fusion protein was mainly cleaved by cyanogen bromide, since enteropeptidase was less effective. The yield of neurotoxin II was 6 mg/l of the bacterial culture. The resulting recombinant protein was identified with native neurotoxin II by its N-terminal analysis, mass spectrometry, and NMR spectroscopy. The English version of the paper: Russian Journal of Bioorganic Chemistry, 2004, vol. 30, no. 1; see also http://www.maik.ru.

    ID:358
  39. Khabibullina N.F., Liukmanova E.N., Kopeina G.S., Shenkarev Z.O., Arsenev A.S., Dolgikh D.A., Kirpichnikov M.P. (2009). [The development and optimization of coupled cell-free expression system for production of the transmembrane domain of the receptor tyrosine kinase ErbB3]. Bioorg. Khim. 36 (5), 654–60 [+]

     

    Разработана сопряженная система бесклеточного синтеза на основе бактериального экстракта S30 из E. coliдля продукции трансмембранного домена рецепторной тирозин-киназы человека ErbB3 (остатки с 632 по 675).Исследованы условия синтеза домена в растворимом виде в присутствии различных детергентов и в виде нерастворимого осадка трансляционной смеси. Подобраны условия очистки рекомбинантного домена, полученного с применением обоих подходов. Конечный выход целевого белка в оптимальных условиях составил 1.8-2.0 мг/мл трансляционной смеси.

    ID:448
  40. Люкманова Е.Н., Копеина Г.С., Шулепко М.А., Шенкарёв З.О., Арсеньев А.С., Долгих Д.А., Кирпичников М.П. (2009). Бесклеточная продукция внеклеточного домена никотинового ацетилхолинового рецептора. Acta Naturae 1, 92–94 ID:450
  41. Lyukmanova E.N., Shenkarev Z.O., Schulga A.A., Ermolyuk Y.S., Mordvintsev D.Y., Utkin Y.N., Shoulepko M.A., Hogg R.C., Bertrand D., Dolgikh D.A., Tsetlin V.I., Kirpichnikov M.P. (2007). Bacterial expression, NMR, and electrophysiology analysis of chimeric short/long-chain alpha-neurotoxins acting on neuronal nicotinic receptors. J. Biol. Chem. 282 (34), 24784–91 [+]

    Different snake venom neurotoxins block distinct subtypes of nicotinic acetylcholine receptors (nAChR). Short-chain alpha-neurotoxins preferentially inhibit muscle-type nAChRs, whereas long-chain alpha-neurotoxins block both muscle-type and alpha7 homooligomeric neuronal nAChRs. An additional disulfide in the central loop of alpha- and kappa-neurotoxins is essential for their action on the alpha7 and alpha3beta2 nAChRs, respectively. Design of novel toxins may help to better understand their subtype specificity. To address this problem, two chimeric toxins were produced by bacterial expression, a short-chain neurotoxin II Naja oxiana with the grafted disulfide-containing loop from long-chain neurotoxin I from N. oxiana, while a second chimera contained an additional A29K mutation, the most pronounced difference in the central loop tip between long-chain alpha-neurotoxins and kappa-neurotoxins. The correct folding and structural stability for both chimeras were shown by (1)H and (1)H-(15)N NMR spectroscopy. Electrophysiology experiments on the nAChRs expressed in Xenopus oocytes revealed that the first chimera and neurotoxin I blockalpha7 nAChRs with similar potency (IC(50) 6.1 and 34 nM, respectively). Therefore, the disulfide-confined loop endows neurotoxin II with full activity of long-chain alpha-neurotoxin and the C-terminal tail in neurotoxin I is not essential for binding. The A29K mutation of the chimera considerably diminished the affinity for alpha7 nAChR (IC(50) 126 nM) but did not convey activity at alpha3beta2 nAChRs. Docking of both chimeras toalpha7 andalpha3beta2 nAChRs was possible, but complexes with the latter were not stable at molecular dynamics simulations. Apparently, some other residues and dimeric organization of kappa-neurotoxins underlie their selectivity for alpha3beta2 nAChRs.

    ID:357
  42. Sharonov G.V., Feofanov A.V., Bocharova O.V., Astapova M.V., Dedukhova V.I., Chernyak B.V., Dolgikh D.A., Arseniev A.S., Skulachev V.P., Kirpichnikov M.P. (2005). Comparative analysis of proapoptotic activity of cytochrome c mutants in living cells. Apoptosis 10 (4), 797–808 [+]

    В работе докладывается о разработке метода измерения проапоптотическй активности экзогенного цитохрома с в живых клетках. Метод основан на введении белка в цитоплазму клетки с помощью электропорации и выявлении с помощью флуоресцентной микроскопии признаков развития апоптоза в клетках. С помощью данного метода были измерены относительные про-апоптозные активности лошадиного цитохрома с и четырех мутантных вариантов данного белка. Обнаружено, что аминокислотная замена К72W полностью блокирует про-апоптозную активность цитохрома с, но не влияет на его «дыхательную» функцию. Методом КОМИРСИ была впервые оценена минимальная цитоплазматическая концентрация лошадиного цитохрома с, необходимая для индукции апоптоза в клетках WEHI-3b.

    ID:94
  43. Bocharov E.V., Lyukmanova E.N., Ermolyuk Ya.S., Shulga A.A., Pluzhnikov K.A., Dolgikh D.A., Kirpichnikov M.P., Arseniev A.S. (2003). Resonance assignment of 13C-15N-labeled snake neurotoxin II from Naja oxiana. 24, 247–254 ID:451