Степанова Анастасия Валерьевна


Научный сотрудник (Лаборатория биокатализа)

Эл. почта: avkaznacheeva@gmail.com

Избранные публикации

  1. Terekhov S.S., Smirnov I.V., Stepanova A.V., Bobik T.V., Mokrushina Y.A., Ponomarenko N.A., Belogurov A.A. Jr, Rubtsova M.P., Kartseva O.V., Gomzikova M.O., Moskovtsev A.A., Bukatin A.S., Dubina M.V., Kostryukova E.S., Babenko V.V., Vakhitova M.T., Manolov A.I., Malakhova M.V., Kornienko M.A., Tyakht A.V., Vanyushkina A.A., Ilina E.N., Masson P., Gabibov A.G., Altman S. (2017). Microfluidic droplet platform for ultrahigh-throughput single-cell screening of biodiversity. Proc. Natl. Acad. Sci. U.S.A. 114 (10), 2550–2555 [+]

    Ultrahigh-throughput screening (uHTS) techniques can identify unique functionality from millions of variants. To mimic the natural selection mechanisms that occur by compartmentalization in vivo, we developed a technique based on single-cell encapsulation in droplets of a monodisperse microfluidic double water-in-oil-in-water emulsion (MDE). Biocompatible MDE enables in-droplet cultivation of different living species. The combination of droplet-generating machinery with FACS followed by next-generation sequencing and liquid chromatography-mass spectrometry analysis of the secretomes of encapsulated organisms yielded detailed genotype/phenotype descriptions. This platform was probed with uHTS for biocatalysts anchored to yeast with enrichment close to the theoretically calculated limit and cell-to-cell interactions. MDE-FACS allowed the identification of human butyrylcholinesterase mutants that undergo self-reactivation after inhibition by the organophosphorus agent paraoxon. The versatility of the platform allowed the identification of bacteria, including slow-growing oral microbiota species that suppress the growth of a common pathogen, Staphylococcus aureus, and predicted which genera were associated with inhibitory activity.

    ID:1962
  2. Smirnov I.V., Golovin A.V., Chatziefthimiou S.D., Stepanova A.V., Peng Y., Zolotareva O.I., Belogurov A.A. Jr, Kurkova I.N., Ponomarenko N.A., Wilmanns M., Blackburn G.M., Gabibov A.G., Lerner R.A. (2016). Robotic QM/MM-driven maturation of antibody combining sites. Sci Adv 2 (10), e1501695 [+]

    In vitro selection of antibodies from large repertoires of immunoglobulin (Ig) combining sites using combinatorial libraries is a powerful tool, with great potential for generating in vivo scavengers for toxins. However, addition of a maturation function is necessary to enable these selected antibodies to more closely mimic the full mammalian immune response. We approached this goal using quantum mechanics/molecular mechanics (QM/MM) calculations to achieve maturation in silico. We preselected A17, an Ig template, from a naïve library for its ability to disarm a toxic pesticide related to organophosphorus nerve agents. Virtual screening of 167,538 robotically generated mutants identified an optimum single point mutation, which experimentally boosted wild-type Ig scavenger performance by 170-fold. We validated the QM/MM predictions via kinetic analysis and crystal structures of mutant apo-A17 and covalently modified Ig, thereby identifying the displacement of one water molecule by an arginine as delivering this catalysis.

    ID:1605
  3. Ponomarenko N., Chatziefthimiou S.D., Kurkova I., Mokrushina Y., Stepanova A., Smirnov I., Avakyan M., Bobik T., Mamedov A., Mitkevich V., Belogurov A., Fedorova O.S., Dubina M., Golovin A., Lamzin V., Friboulet A., Makarov A.A., Wilmanns M., Gabibov A. (2014). Role of κ→λ light-chain constant-domain switch in the structure and functionality of A17 reactibody. Acta Crystallogr. D Biol. Crystallogr. 70 (Pt 3), 708–19 [+]

    The engineering of catalytic function in antibodies requires precise information on their structure. Here, results are presented that show how the antibody domain structure affects its functionality. The previously designed organophosphate-metabolizing reactibody A17 has been re-engineered by replacing its constant κ light chain by the λ chain (A17λ), and the X-ray structure of A17λ has been determined at 1.95 Å resolution. It was found that compared with A17κ the active centre of A17λ is displaced, stabilized and made more rigid owing to interdomain interactions involving the CDR loops from the VL and VH domains. These VL/VH domains also have lower mobility, as deduced from the atomic displacement parameters of the crystal structure. The antibody elbow angle is decreased to 126° compared with 138° in A17κ. These structural differences account for the subtle changes in catalytic efficiency and thermodynamic parameters determined with two organophosphate ligands, as well as in the affinity for peptide substrates selected from a combinatorial cyclic peptide library, between the A17κ and A17λ variants. The data presented will be of interest and relevance to researchers dealing with the design of antibodies with tailor-made functions.

    ID:1245