Biology subjects

Kesarwani, S.

Publications and source records attributed to Kesarwani, S..

3 recordsLinked to original sources

bioRxiv2022

Peptide derived nanobody inhibits entry of SARS-CoV-2 variants

Emergence of the new escape mutants of the SARS-CoV-2 virus has escalated its penetration among the human population and has reinstated its status as a global pandemic. Therefore, developing effective antiviral therapy against emerging SARS variants and other viruses in a short period of time becomes essential. Blocking the SARS-CoV-2 entry into human host cells by disrupting the spike glycoprotein-ACE2 interaction has been already exploited for vaccine development and monoclonal antibody therapy. Unlike the previous reports, our study used a 9 amino acid peptide from the receptor-binding motif (RBM) of Spike (S) protein as an epitope. We report the identification of an efficacious nanobody N1.2 that blocks the entry of pseudovirus containing SARS-CoV-2 spike as the surface glycoprotein. Moreover, we observe a more potent neutralizing effect against both the hCoV19 (Wuhan/WIV04/2019) and the Omicron (BA.1) pseudotyped spike virus with a bivalent version of the nanobody. In summary, our study presents a faster and efficient methodology to use peptide sequences from a protein-receptor interaction interface as epitopes for screening nanobodies against potential pathogenic targets. This approach can also be widely extended to target other viruses and pathogens in the future.

cell biology↗

bioRxiv2020

Genetically encoded live cell sensor for tyrosinated microtubules

Microtubule cytoskeleton exists in various biochemical forms in different cells due to tubulin post-translational modification (PTMs). These PTMs are known to affect microtubule stability, dynamics and interaction with MAPs and motors in a specific manner, widely known as tubulin code hypothesis. At present there exist no tool that can specifically mark tubulin PTMs in live cells, thus severely limiting our understanding of tubulin PTMs. Using yeast display library, we identified a binder against terminal tyrosine of alpha tubulin, a unique PTM site. Extensive characterization validates the robustness and non-perturbing nature of our binder as tyrosination sensor, a live cell tubulin nanobody specific towards tyrosinated or unmodified microtubules. Using which, in real time we followed nocodazole, colchicine and vincristine induced depolymerization events of unmodified microtubules, and found each distinctly perturb microtubule polymer. Together, our work describes the tyrosination sensor and potential applications to study microtubule and PTM processes in living cells.

cell biology↗

bioRxiv2019

Structural insights into filament recognition by cellular actin markers

Cellular studies of filamentous actin (F-actin) processes commonly utilize fluorescent versions of toxins, peptides and proteins that bind actin. While the choice of these markers has been largely based on availability and ease, there is a severe dearth of structural data for an informed judgment in employing suitable F-actin markers for a particular requirement. Here we describe the electron cryomicroscopy structures of phalloidin, lifeAct and utrophin bound to F-actin, providing the first high-resolution structures and comparison of widely used actin markers and their influence towards F-actin. Our results show that phalloidin binding does not induce conformations and lifeAct specifically recognizes ADP-actin state, which can be used as a sensor for distinguishing different nucleotide states of F-actin. The utrophin structural model aided designing minimal utrophin, which can be utilized as F-actin marker. Together, our study provides a structural perspective, where the binding sites of utrophin and lifeAct overlap with majority of actin binding proteins. Further offering an invaluable resource for researchers in choosing appropriate actin markers and generating new marker variants.

cell biology↗