Biology subjects

Shvetsov, A.

Publications and source records attributed to Shvetsov, A..

6 recordsLinked to original sources

bioRxiv2026

DSSNA: An Open-Source GROMACS Module for Automated Analysis of Nucleic Acid Secondary and Tertiary Structure in Molecular Dynamics Simulations

This work presents DSSNA (Define Spatial Structure of Nucleic Acids) v2026, a free and open-source standalone GROMACS module for the automated analysis of nucleic acid structure based on atomic coordinates. DSSNA reproduces the core functionality of the X3DNA and DSSR approach while extending it to the analysis of molecular dynamics trajectories through integration with the GROMACS software package. The algorithm identifies and classifies structural features, including canonical and noncanonical base pairs, hydrogen-bond networks, stacking interactions, helices, and many other elements of nucleic acid secondary and tertiary structure. Its modular output system enables users to select the structural metrics required for a particular analysis, while the use of neighbor-search algorithms and data-processing capabilities facilitates the analysis of large trajectory datasets. The performance and applicability of DSSNA were demonstrated using a molecular dynamics trajectory of a GUAA tetraloop mutant of the sarcin-ricin domain from Escherichia coli 23S ribosomal RNA (PDB ID: 1MSY). The analysis showed that only a subset of the observed base pairs and stacking interactions remains stable throughout the trajectory. Persistent canonical base pairs formed the structural core responsible for maintaining the secondary-structure profile, whereas most noncanonical base pairs and stacking interactions were transient. The results demonstrate that DSSNA can be used to characterize both static nucleic acid structures and the temporal evolution of structural interactions in molecular dynamics simulations. The work also provides a glossary of terms relevant to the analysis and interpretation of nucleic acid structures.

bioinformatics↗

bioRxiv2023

Determination of hydrogen bonds in Gromacs: new implementation to overcome the limitation

This work describes a new software algorithm associated with determination of hydrogen bonds in biomacromolecules and their environment. The already existing algorithm for determining hydrogen bond networks in Gromacs has a number of impenetrable limitations in the analysis of structures and trajectories. The new implementation of the algorithm for determining hydrogen bond networks in the form of a native Gromacs trajectory analysis module allows to quickly analyze molecular dynamics trajectories without restrictions, thereby overcoming the limitation of original algorithm. The application of the developed algorithm made it possible to obtain and analyze the networks of hydrogen bonds of the studied defensin-like protein Pentadiplandra brazzeana, as well as to study the lifetime of hydrogen bonds between the residues of this protein and water molecules. The data obtained using the new implementation coincided with the experimental one. TOC Graphic O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=110 SRC="FIGDIR/small/555860v2_ufig1.gif" ALT="Figure 1"> View larger version (19K): org.highwire.dtl.DTLVardef@81727aorg.highwire.dtl.DTLVardef@82de36org.highwire.dtl.DTLVardef@1cad89forg.highwire.dtl.DTLVardef@53ec2a_HPS_FORMAT_FIGEXP M_FIG C_FIG

bioinformatics↗

bioRxiv2019

Cold and distant: structural features of the nucleoprotein complex of a cold-adapted influenza A virus strain

Two influenza A nucleoprotein variants (wt: G102R; and mutant: G102R and E292G) were studied with regard to macro-molecular interactions in oligomeric form (24-mers). The E292G mutation has been previously shown to provide cold adaptation. Molecular dynamics simulations of these complexes and trajectory analysis showed that the most significant difference between the obtained models was distance differences between nucleoprotein complex strands. Influenza virus nucleoprotein complexes were isolated from strains bearing the corresponding NP amino acid substitutions. The isolated complexes were characterized by transmission electron microscopy and differential scanning fluorimetry (DSF). Presence of the E292G substitution was shown by DSF to affect nucleoprotein complex melting temperature. In the filament interface peptide model, it was shown that the peptide corresponding in primary structure to the wild-type NP (SGYDFEREGYS, wild type peptide) is prone to temperature-dependent self-association, unlike the peptide carrying the substitution corresponding to E292G (SGYDFGREGYS, mutant peptide). It was also shown that the SGYDFEREGYS peptide (wt) is capable of interacting with a recombinant full-size monomeric nucleoprotein (with primary structure corresponding to wild type); this interactions equilibrium dissociation constant is five orders of magnitude lower than for the SGYDFGREGYS peptide. Using small-angle neutron scattering (SANS), the supramolecular structures of isolated complexes of these proteins was studied at temperatures of 15, 32, and 37{degrees}C. SANS data show that the structures of the studied complexes (mutant or normal proteins with RNA) at elevated temperature differ from the rod-like particle model and react differently to temperature changes. The data suggest that the mechanism behind cold adaptation with E292G is associated with a weakening of the interaction between strands of the ribonucleoprotein complex and, as a result, the appearance of inter-chain interface flexibility necessary for complex function at low temperature.

biophysics↗

bioRxiv2019

Effect of Alpha-Lactalbumin and Lactoferrin Oleic Acid Complexes on Chromatin Structural Organization

This work focuses on the study of multimeric alpha-lactalbumin oleic acid and lactoferrin oleic acid complexes. The purpose of the research is to study possible mechanisms involved in their pro-apoptotic activities, as seen in some tumor cell cultures. Complexes featuring oleic acid (OA) with human alpha-lactalbumin (hAl) or with bovine alpha-lactalbumin (bAl), and human lactoferrin (hLf) were investigated using small-angle neutron scattering (SANS). It was shown that while alpha-lactalbumin protein complexes were formed on the surface of polydisperse OA micelles, the lactoferrin complexes comprised a monodisperse system of nanoscale particles. Both hAl and hLf complexes appeared to interact with the chromatin of isolated nuclei affecting chromatin structural organization. The possible roles of these processes in the specific anti-tumor activity of these complexes are discussed.

biophysics↗

bioRxiv2019

Thermostability improvement of Aspergillus awamori glucoamylase via directed evolution of its gene located on episomal expression vector in Pichia pastoris

Novel thermostable forms of glucoamylase (GA) from filamentous fungus Aspergillus awamori X100 were constructed using the directed evolution approach based on random mutagenesis by error-prone PCR of the catalytic domain region of glucoamylase gene with its localization on a new episomal expression vector pPEH in Pichia pastoris cells. Of 3000 yeast transformants screened, six new thermostable GA mutants with amino acid substitutions Val301Asp, Thr390Ala, Thr390Ala/Ser436Pro, Leu7Met/His391Tyr, Asp9His/Ile82Phe, Ser8Arg/Gln338Leu were identified and studied. To estimate the effect of every single substitution in the double mutants, we have constructed an appropriate single mutants of GA by site-directed mutagenesis and analyzed their thermal properties. Results of the analysis showed that only Ile82Phe and Ser8Arg mutations caused an increased thermostability. While Leu7Met and Asp9His mutations decreased the thermal stability of GA, and Gln338Leu had little effect, the synergistic effect of double mutant forms Leu7Met/His391Tyr, Asp9His/Ile82Phe and Ser8Arg/Gln338Leu revealed the significant thermostability improvement as compared to wild type GA.

molecular biology↗

bioRxiv2017

Triazavirine supramolecular complexes as modifiers of the peptide oligomeric structure

In this study we present molecular dynamics simulations of the antiviral drug triazavirine, that affects formation of amyloid-like fibrils of the model peptide (SI). According to our simulations, triazavirine is able to form linear supramolecular structures which can act as shields and prevent interactions between SI monomers. This model, as validated by simulations, provides an adequate explanation of triazavirines mechanism of action as it pertains to SI peptide fibril formation.

biophysics↗