Group of bioengineering of neuromodulators and neuroreceptors

Selected publications

  1. Shenkarev Z.O., Karlova M.G., Kulbatskii D.S., Kirpichnikov M.P., Lyukmanova E.N., Sokolova O.S. (2018). Recombinant Production, Reconstruction in Lipid-Protein Nanodiscs, and Electron Microscopy of Full-Length α-Subunit of Human Potassium Channel Kv7.1. Biochemistry Mosc. 83 (5), 562–573 [+]

    Voltage-gated potassium channel Kv7.1 plays an important role in the excitability of cardiac muscle. The α-subunit of Kv7.1 (KCNQ1) is the main structural element of this channel. Tetramerization of KCNQ1 in the membrane results in formation of an ion channel, which comprises a pore and four voltage-sensing domains. Mutations in the human KCNQ1 gene are one of the major causes of inherited arrhythmias, long QT syndrome in particular. The construct encoding full-length human KCNQ1 protein was synthesized in this work, and an expression system in the Pichia pastoris yeast cells was developed. The membrane fraction of the yeast cells containing the recombinant protein (rKCNQ1) was solubilized with CHAPS detergent. To better mimic the lipid environment of the channel, lipid-protein nanodiscs were formed using solubilized membrane fraction and MSP2N2 protein. The rKCNQ1/nanodisc and rKCNQ1/CHAPS samples were purified using the Rho1D4 tag introduced at the C-terminus of the protein. Protein samples were examined using transmission electron microscopy with negative staining. In both cases, homogeneous rKCNQ1 samples were observed based on image analysis. Statistical analysis of the images of individual protein particles solubilized in the detergent revealed the presence of a tetrameric structure confirming intact subunit assembly. A three-dimensional channel structure reconstructed at 2.5-nm resolution represents a compact density with diameter of the membrane part of ~9 nm and height ~11 nm. Analysis of the images of rKCNQ1 in nanodiscs revealed additional electron density corresponding to the lipid bilayer fragment and the MSP2N2 protein. These results indicate that the nanodiscs facilitate protein isolation, purification, and stabilization in solution and can be used for further structural studies of human Kv7.1.

  2. Männikkö R., Shenkarev Z.O., Thor M.G., Berkut A.A., Myshkin M.Y., Paramonov A.S., Kulbatskii D.S., Kuzmin D.A., SampedroCastañeda M., King L., Wilson E.R., Lyukmanova E.N., Kirpichnikov M.P., Schorge S., Bosmans F., Hanna M.G., Kullmann D.M., Vassilevski A.A. (2018). Spider toxin inhibits gating pore currents underlying periodic paralysis. Proc. Natl. Acad. Sci. U.S.A. 115 (17), 4495–4500 [+]

    Gating pore currents through the voltage-sensing domains (VSDs) of the skeletal muscle voltage-gated sodium channel Na1.4 underlie hypokalemic periodic paralysis (HypoPP) type 2. Gating modifier toxins target ion channels by modifying the function of the VSDs. We tested the hypothesis that these toxins could function as blockers of the pathogenic gating pore currents. We report that a crab spider toxin Hm-3 from can inhibit gating pore currents due to mutations affecting the second arginine residue in the S4 helix of VSD-I that we have found in patients with HypoPP and describe here. NMR studies show that Hm-3 partitions into micelles through a hydrophobic cluster formed by aromatic residues and reveal complex formation with VSD-I through electrostatic and hydrophobic interactions with the S3b helix and the S3-S4 extracellular loop. Our data identify VSD-I as a specific binding site for neurotoxins on sodium channels. Gating modifier toxins may constitute useful hits for the treatment of HypoPP.

  3. Lyukmanova E.N., Bychkov M.L., Sharonov G.V., Efremenko A.V., Shulepko M.A., Kulbatskii D.S., Shenkarev Z.O., Feofanov A.V., Dolgikh D.A., Kirpichnikov M.P. (2018). Human secreted proteins SLURP-1 and SLURP-2 control the growth of epithelial cancer cells via interactions with nicotinic acetylcholine receptors. Br. J. Pharmacol. , [+]

    Nicotinic acetylcholine receptors (nAChRs) are a promising target for development of new anticancer therapies. Here we have investigated the effects of the endogenous human proteins SLURP-1 and SLURP-2, antagonists of nAChRs, on human epithelial cancer cells.

  4. Vasilyeva N.A., Loktyushov E.V., Bychkov M.L., Shenkarev Z.O., Lyukmanova E.N. (2017). Three-Finger Proteins from the Ly6/uPAR Family: Functional Diversity within One Structural Motif. Biochemistry Mosc. 82 (13), 1702–1715 [+]

    The discovery in higher animals of proteins from the Ly6/uPAR family, which have structural homology with snake "three-finger" neurotoxins, has generated great interest in these molecules and their role in the functioning of the organism. These proteins have been found in the nervous, immune, endocrine, and reproductive systems of mammals. There are two types of the Ly6/uPAR proteins: those associated with the cell membrane by GPI-anchor and secreted ones. For some of them (Lynx1, SLURP-1, SLURP-2, Lypd6), as well as for snake α-neurotoxins, the target of action is nicotinic acetylcholine receptors, which are widely represented in the central and peripheral nervous systems, and in many other tissues, including epithelial cells and the immune system. However, the targets of most proteins from the Ly6/uPAR family and the mechanism of their action remain unknown. This review presents data on the structural and functional properties of the Ly6/uPAR proteins, which reveal a variety of functions within a single structural motif.

  5. Dubovskii P.V., Dubinnyi M.A., Konshina A.G., Kazakova E.D., Sorokoumova G.M., Ilyasova T.M., Shulepko M.A., Chertkova R.V., Lyukmanova E.N., Dolgikh D.A., Arseniev A.S., Efremov R.G. (2017). Structural and Dynamic "Portraits" of Recombinant and Native Cytotoxin I from Naja oxiana: How Close Are They? Biochemistry 56 (34), 4468–4477 [+]

    Today, recombinant proteins are quite widely used in biomedical and biotechnological applications. At the same time, the question about their full equivalence to the native analogues remains unanswered. To gain additional insight into this problem, intimate atomistic details of a relatively simple protein, small and structurally rigid recombinant cardiotoxin I (CTI) from cobra Naja oxiana venom, were characterized using nuclear magnetic resonance (NMR) spectroscopy and atomistic molecular dynamics (MD) simulations in water. Compared to the natural protein, it contains an additional Met residue at the N-terminus. In this work, the NMR-derived spatial structure of uniformly (13)C- and (15)N-labeled CTI and its dynamic behavior were investigated and subjected to comparative analysis with the corresponding data for the native toxin. The differences were found in dihedral angles of only a single residue, adjacent to the N-terminal methionine. Microsecond-long MD traces of the toxins reveal an increased flexibility in the residues spatially close to the N-Met. As the detected structural and dynamic changes of the two CTI models do not result in substantial differences in their cytotoxicities, we assume that the recombinant protein can be used for many purposes as a reasonable surrogate of the native one. In addition, we discuss general features of the spatial organization of cytotoxins, implied by the results of the current combined NMR and MD study.

  6. Stenkova A.M., Chopenko N.S., Davydova L.A., Mazeika A.N., Bystritskaya E.P., Portnyagina O.Y., Anastyuk S.D., Kulbatskii D.S., Lyukmanova E.N., Dolgikh D.A., Kostetsky E.Y., Sanina N.M. (2017). Engineering of Chimeric Protein Based on E Protein Domain III of Tick-Borne Encephalitis Virus and OmpF Porin of Yersinia pseudotuberculosis. Protein Pept. Lett. , [+]

    Tick-borne encephalitis poses a serious public health threat in the endemic regions. The disease treatment is restricted to symptomatic therapy, so great expectations are in the development of the prophylactic and therapeutic vaccines. The domain III of E protein of the tick-borne encephalitis virus is the main antigenic domain which includes virus-specific epitopes recognized by neutralizing antibodies. We have expressed, isolated and characterized the chimeric protein based on the fusion of domain III of E protein of the tick-borne encephalitis virus and bacterial porin OmpF from Yersinia pseudotuberculosis. The bacterial partner protein was used for decreasing toxicity and increasing immunogenicity of antigen. The chimeric protein was successfully expressed by the E. coli cells and purified using IMAC methodology. The purified protein was recognized with immunoblots by anti-E protein of tick-borne encephalitis virus monoclonal antibodies. Furthermore, the protein was able to elicit antibody response against domain III of E protein in immunized mice. The newly obtained chimeric antigen could be valuable for the development of the preventing tick-borne encephalitis subunit vaccines.

  7. Paramonov A.S., Lyukmanova E.N., Myshkin M.Y., Shulepko M.A., Kulbatskii D.S., Petrosian N.S., Chugunov A.O., Dolgikh D.A., Kirpichnikov M.P., Arseniev A.S., Shenkarev Z.O. (2017). NMR investigation of the isolated second voltage-sensing domain of human Nav1.4 channel. Biochim. Biophys. Acta 1859 (3), 493–506 [+]

    Voltage-gated Na(+) channels are essential for the functioning of cardiovascular, muscular, and nervous systems. The α-subunit of eukaryotic Na(+) channel consists of ~2000 amino acid residues and encloses 24 transmembrane (TM) helices, which form five membrane domains: four voltage-sensing (VSD) and one pore domain. The structural complexity significantly impedes recombinant production and structural studies of full-sized Na(+) channels. Modular organization of voltage-gated channels gives an idea for studying of the isolated second VSD of human skeletal muscle Nav1.4 channel (VSD-II). Several variants of VSD-II (~150a.a., four TM helices) with different N- and C-termini were produced by cell-free expression. Screening of membrane mimetics revealed low stability of VSD-II samples in media containing phospholipids (bicelles, nanodiscs) associated with the aggregation of electrically neutral domain molecules. The almost complete resonance assignment of (13)C,(15)N-labeled VSD-II was obtained in LPPG micelles. The secondary structure of VSD-II showed similarity with the structures of bacterial Na(+) channels. The fragment of S4 TM helix between the first and second conserved Arg residues probably adopts 310-helical conformation. Water accessibility of S3 helix, observed by the Mn(2+) titration, pointed to the formation of water-filled crevices in the micelle embedded VSD-II. (15)N relaxation data revealed characteristic pattern of μs-ms time scale motions in the VSD-II regions sharing expected interhelical contacts. VSD-II demonstrated enhanced mobility at ps-ns time scale as compared to isolated VSDs of K(+) channels. These results validate structural studies of isolated VSDs of Na(+) channels and show possible pitfalls in application of this 'divide and conquer' approach.

  8. Парамонов А.С., Кульбацкий Д.С., Локтюшов Е.В., Царев А.В., Долгих Д.А., Шенкарёв З.О., Кирпичников М.П., Люкманова Е.Н. (2017). Рекомбинантная продукция и исследование структуры белков человека Lypd6 и Lypd6b. Биоорг. хим. 43 (6), 620–630 [+]

    Белки человека Lypd6 и Lypd6b экспрессируются во многих тканях и имеют высокую степень гомо-
    логии аминокислотной последовательности (~ 54%). Оба белка в отличие от других белков семейства
    Ly6/uPAR имеют дополнительные протяженные N- и С-концевые аминокислотные последователь-
    ности, примыкающие к трехпетельному LU-домену, роль которых на данный момент не изучена. Из-
    вестно, что Lypd6 увеличивает амплитуду токов кальция, индуцированных никотином в нейронах
    тройничного нерва мыши. Lypd6 рыбки Danio rerio участвует в регуляции Wnt/β-катенин сигнального
    каскада, и блокирование экспрессии гена lypd6 приводит к нарушению эмбрионального развития.
    Экспрессия Lypd6b в ооцитах X. laevis повышает чувствительность никотиновых ацетилхолиновых ре-
    цепторов к ацетилхолину и увеличивает скорость их десенситизации. Молекулярные механизмы дей-
    ствия, равно как и пространственная структура Lypd6 и Lypd6b, до сих пор не изучены. В представ-
    ленной работе получены и экспрессированы гены водорастворимых аналогов трехпетельных белков
    человека Lypd6 и Lypd6b, не содержащих N-концевые последовательности (rLypd6 и rLypd6b), а также
    Lypd6 с N-концевой последовательностью – N-rLypd6. Белки получали в виде цитоплазматических
    телец включения в E. coli с последующей солюбилизацией в денатурирующих условиях и ренатураци-
    ей. С целью оптимизации выхода рекомбинантных белков был проведен поиск условий ренатурации.
    Анализ полученных препаратов N-rLypd6, rLypd6 и rLypd6b методами ЯМР-спектроскопии показал,
    что N-rLypd6, возможно, не структурирован. Получение миллиграммовых количеств изотопно-ме-
    ченных вариантов rLypd6 и rLypd6b позволило охарактеризовать вторичную структуру этих белков
    и исследовать внутримолекулярную подвижность. Установлено, что rLypd6 и rLypd6b обладают струк-
    турными элементами, характерными для трехпетельных белков семейства Ly6/uPAR с некоторыми
    уникальными особенностями, такими как наличие дополнительной дисульфидной связи в третьей
    петле и спиральных участков в первой и третьей петлях.


    Потенциал-зависимые K+- и Na+-ионные каналы вовлечены в широкий спектр физиологических
    процессов, включая возбудимость сердечных, мышечных и нервных клеток, а также секрецию гор-
    монов и нейромедиаторов. Эти каналы имеют модульную структуру и состоят из пяти мембранных
    доменов: четырех потенциал-чувствительных доменов (ПЧД) и одного порового домена. На ПЧД раз-
    личных каналов локализованы уникальные сайты связывания с лигандами, поэтому ПЧД рассматри-
    ваются в качестве перспективных фармакологических мишеней. Модульная организация ионных ка-
    налов позволяет ставить задачи по структурным ЯМР-исследованиям изолированных ПЧД отдельно
    от поры. В настоящей работе рассмотрена возможность таких исследований на примере ПЧД канала
    Kv2.1 человека и первого ПЧД канала Nav1.4 человека. Разработаны сопряженные системы бескле-
    точного синтеза на основе бактериального экстракта S30 из E. coli, позволяющие получать милли-
    граммовые количества препаратов ПЧД, включая меченые стабильными изотопами аналоги. Важным
    этапом ЯМР-исследований является подбор мембраномоделирующей среды, обеспечивающей дол-
    говременную стабильность природной структуры мембранного белка в растворе и высокое качество
    ЯМР-спектров. Скрининг различных сред показал, что домены каналов Kv2.1 и Nav1.4 нестабильны
    в средах, содержащих фосфолипиды: мицеллах короткоцепочечного липида DC7PC и липид-детер-
    гентных бицеллах на основе цвиттер-ионных или анионных насыщенных липидов (DMPC и DMPG).
    Показано, что оптимальной средой для структурных ЯМР-исследований являются смеси цвиттер-
    ионного и слабокатионного детергентов (FOS-12/LDAO). Однако, несмотря на высокое качество
    спектров, образец ПЧД канала Nav1.4 в окружении FOS-12/LDAO необратимо агрегировал в течение
    нескольких дней. Вероятно, ПЧД K+- и Na+-каналов человека не являются полностью автономными
    мембранными доменами и для их стабилизации необходимы контакты с другими доменами канала.

  10. Васильева Н.А., Локтюшов Е.В., Бычков М.Л., Шенкарёв З.О., Люкманова Е.Н. (2017). Трехпетельные белки семейства Ly6/uPAR: функциональное многообразие в рамках одного структурного мотива. Успехи биологической химии 57, 303–330 ID:1931
  11. 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.

  12. 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.

  13. 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.

  14. 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.

  15. 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.

  16. 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.

  17. 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.

  18. Berkut A.A., Peigneur S., Myshkin M.Y., Paramonov A.S., Lyukmanova E.N., Arseniev A.S., Grishin E.V., Tytgat J., Shenkarev Z.O., Vassilevski A.A. (2015). Structure of Membrane-active Toxin from Crab Spider Heriaeus melloteei Suggests Parallel Evolution of Sodium Channel Gating Modifiers in Araneomorphae and Mygalomorphae. J. Biol. Chem. 290 (1), 492–504 [+]

    We present a structural and functional study of a sodium channel activation inhibitor from crab spider venom. Hm-3 is an insecticidal peptide toxin consisting of 35 amino acid residues from the spider Heriaeus melloteei (Thomisidae). We produced Hm-3 recombinantly in Escherichia coli and determined its structure by NMR spectroscopy. Typical for spider toxins, Hm-3 was found to adopt the so-called "inhibitor cystine knot" or "knottin" fold stabilized by three disulfide bonds. Its molecule is amphiphilic with a hydrophobic ridge on the surface enriched in aromatic residues and surrounded by positive charges. Correspondingly, Hm-3 binds to both neutral and negatively charged lipid vesicles. Electrophysiological studies showed that at a concentration of 1 μm Hm-3 effectively inhibited a number of mammalian and insect sodium channels. Importantly, Hm-3 shifted the dependence of channel activation to more positive voltages. Moreover, the inhibition was voltage-dependent, and strong depolarizing prepulses attenuated Hm-3 activity. The toxin is therefore concluded to represent the first sodium channel gating modifier from an araneomorph spider and features a "membrane access" mechanism of action. Its amino acid sequence and position of the hydrophobic cluster are notably different from other known gating modifiers from spider venom, all of which are described from mygalomorph species. We hypothesize parallel evolution of inhibitor cystine knot toxins from Araneomorphae and Mygalomorphae suborders.


Ekaterina Lyukmanova