bioRxiv Science⌕ Search

Biology subjects

Sumbul, F.

Publications and source records attributed to Sumbul, F..

3 recordsLinked to original sources

PySteMoDA: An Open Source Python Package for the Analysis of Steered Molecular Dynamics Simulations Data

Molecular dynamics simulation is a powerful computational technique used for predicting and understanding the dynamic behavior of biomolecular systems. Steered molecular dynamics (SMD) simulations enable the study of force-induced processes in biomolecules, effectively mimicking single-molecule force spectroscopy experiments probing protein unfolding and receptor-ligand unbinding. Given the stochastic nature of these mechanical events, accurately exploring the dynamic behavior of biomolecules and extracting accurate physical information requires several in-silico experiments. This includes performing many pulling simulations at different velocities or force loading rates. The large amount of data obtained from these simulation sets requires efficient automated data processing tools. We present PySteMoDA, a novel Python package with a user-friendly graphical interface specifically designed for constant-velocity SMD data analysis. The automated force peak detection methods reduce user bias, improve accuracy, and accelerate data analysis. The package also allows identification of residues involved in mechanical events through computation of the time-dependent mechanical work and correlation factors between residue pairs. This package not only addresses automated data processing in SMD simulations and accurate parameter extraction, but also significantly enhances accessibility and usability. Through PySteMoDA, users can efficiently analyze simulation data without the barrier of coding, facilitating a wider range of investigations and insights in the field of computational biochemistry and biophysics.

biophysics↗

Modulation of SARS-CoV-2 spike binding to ACE2 throughconformational selection

The first step of SARS-CoV-2 infection involves the interaction between the trimeric viral spike protein (S) and the host angiotensin-converting enzyme 2 (ACE2). The receptor binding domain (RBD) of S adopts two conformations: open and closed, respectively, accessible and inaccessible to ACE2. Therefore, RBD motions are suspected to affect ACE2 binding; yet a quantitative description of the underlying mechanism has been elusive. Here, using single-molecule approaches, we visualize RBD opening and closing and probe the S/ACE2 interaction. Our results show that RBD dynamics affect ACE2 binding but not unbinding. The resulting modulation is quantitatively predicted by a conformational selection model in which each protomer behaves independently. Our work reveals a general molecular mechanism affecting binding affinity without altering binding strength, helping to understand coronavirus infection and immune evasion.

biophysics↗

Epistatic effects between amino acid insertions and substitutions mediate toxin-resistance of vertebrate Na+,K+-ATPases

The recurrent evolution of resistance to cardiotonic steroids (CTS) across diverse animals most frequently involves convergent amino-acid substitutions to the H1-H2 extracellular loop of Na+,K+-ATPase (NKA). Previous work established that hystricognath rodents (e.g. chinchilla) and pterocliform birds (sandgrouse) have convergently evolved amino-acid insertions in the H1-H2 loop, but their functional significance is not known. Using protein engineering, we show that these insertions have distinct effects on CTS resistance of NKA in the two lineages that strongly depend on intramolecular interactions with other residues. Removing the insertion in the chinchilla lineage unexpectedly increases CTS resistance and decreases NKA activity. In the sandgrouse lineage, the insertion works in concert with the substitution Q111R to increase CTS resistance while maintaining wild-type ATPase activity levels. Molecular docking simulations provide additional insight into the biophysical mechanisms responsible for the context-specific CTS insensitivity of the enzyme. Our results highlight the diversity of genetic substrates that underlie CTS insensitivity in vertebrate NKA and reveal how amino-acid insertions can alter the phenotypic effects of point mutations at key sites in the same protein domain.

evolutionary biology↗