Anastasija G. Konshina

Selected publications

  1. Dubovskii P.V., Konshina A.G., Efremov R.G. (2013). Cobra Cardiotoxins: Membrane Interactions and Pharmacological Potential. Curr. Med. Chem. 21 (3), 270–287 [+]

    Natural polycationic membrane-active peptides typically lack disulfide bonds and exhibit fusion, cell-penetrating, antimicrobial activities. They are mostly unordered in solution, but adopt a helical structure, when bound to phospholipid membranes. Structurally different are cardiotoxins (or cytotoxins, СTs) from cobra venom. They are fully -structured molecules, characterized by the three-finger fold (TFF). Affinity of CTs to lipid bilayer was shown to depend on amino acid sequence in the tips of the three loops. In the present review, CT-membrane interactions are analyzed through the prism of data on binding of the toxins to phospholipid liposomes and detergent micelles, as well as their structural and computational studies in membrane mimicking environments. We assess different hydrophobicity scales to compare membrane partitioning of various CTs and their membrane effects. A comparison of hydrophobic/hydrophilic properties of CTs and linear polycationic peptides provides a key to their biological activity and creates a fundamental basis for rational design of new membrane-interacting compounds, including new promising drugs. For instance, since the viewpoint of the data obtained on model lipid membranes, cytotoxic activity of CTs against cancer cells is discussed.

  2. Konshina A.G., Dubovskii P.V., Efremov R.G. (2012). Structure and dynamics of cardiotoxins. Curr. Protein Pept. Sci. 13 (6), 570–84 [+]

    Cytotoxins (or cardiotoxins; CTs) are toxins from cobra venom characterized by the three-finger (TF) fold. CTs are on average 60-residue-long peptides, possessing as many as 4 disulfide bonds. The elements of antiparallel β-structure take origin from the hydrophobic core formed by the disulfides. The β-strands adopt the shape of the three loops, giving the name of the fold. While neurotoxins (NTs) - also TF proteins from snake venom - exert their effect through specific interactions with protein receptors, no specific protein target has been found for CTs. Unlike NTs, CTs are amphiphilic and cytotoxic against a variety of cells, including cancer ones. Thus, the hypothesis that the activity of CTs is caused by their interactions with lipid membranes is currently central. To understand molecular basis behind variations in toxicities of CTs highly homologous in their sequences, detailed knowledge of their structure and dynamics is required. The present review summarizes experimental and computational data on the spatial organization of CTs and their dynamics in various environments (aqueous solution, membranous milieus).

  3. Konshina A.G., Boldyrev I.A., Utkin Y.N., Omelkov A.V., Efremov R.G. (2011). Snake cytotoxins bind to membranes via interactions with phosphatidylserine head groups of lipids. PLoS ONE 6 (4), e19064 [+]

    The major representatives of Elapidae snake venom, cytotoxins (CTs), share similar three-fingered fold and exert diverse range of biological activities against various cell types. CT-induced cell death starts from the membrane recognition process, whose molecular details remain unclear. It is known, however, that the presence of anionic lipids in cell membranes is one of the important factors determining CT-membrane binding. In this work, we therefore investigated specific interactions between one of the most abundant of such lipids, phosphatidylserine (PS), and CT 4 of Naja kaouthia using a combined, experimental and modeling, approach. It was shown that incorporation of PS into zwitterionic liposomes greatly increased the membrane-damaging activity of CT 4 measured by the release of the liposome-entrapped calcein fluorescent dye. The CT-induced leakage rate depends on the PS concentration with a maximum at approximately 20% PS. Interestingly, the effects observed for PS were much more pronounced than those measured for another anionic lipid, sulfatide. To delineate the potential PS binding sites on CT 4 and estimate their relative affinities, a series of computer simulations was performed for the systems containing the head group of PS and different spatial models of CT 4 in aqueous solution and in an implicit membrane. This was done using an original hybrid computational protocol implementing docking, Monte Carlo and molecular dynamics simulations. As a result, at least three putative PS-binding sites with different affinities to PS molecule were delineated. Being located in different parts of the CT molecule, these anion-binding sites can potentially facilitate and modulate the multi-step process of the toxin insertion into lipid bilayers. This feature together with the diverse binding affinities of the sites to a wide variety of anionic targets on the membrane surface appears to be functionally meaningful and may adjust CT action against different types of cells.