Biology subjects

Kayastha, A.

Publications and source records attributed to Kayastha, A..

3 recordsLinked to original sources

bioRxiv2026

Structural Insights into the Expanded Substrate Scope of a Cysteine-Dependent Hydrolase from Rhodococcus opacus for Polyethylene, Polypropylene, and Polystyrene Biodegradation

Microplastic pollution from homopolymers such as polypropylene (PP), polystyrene (PS), and polyethylene (PE) poses growing health and environmental concerns, highlighting the need for robust polymer-degrading biocatalysts. We previously identified a naturally occurring cysteine-dependent hydrolase (CsdH) from Rhodococcus opacus, featuring a unique Cys160-Lys127-Asp39 catalytic triad and providing a novel mechanism for polyethylene terephthalate (PET) degradation. In this study, we have determined crystal structures of CsdH in complex with PP, PS, PE, and styrene and demonstrated the potential of the enzyme to directly degrade these homopolymers into their respective low molecular weight degradation products using LC-MS. Structural analysis reveals that the enzyme retains a conserved principal access tunnel while undergoing subtle substrate-dependent changes to accommodate different substrates. The enzyme exhibited broad plastic degradation activity with the highest weight loss observed for PE, followed by PP and PS. SEM analysis reveals surface roughness, cracks and grooves, confirming polymer degradation. Further, these results corroborate through FTIR and TGA analysis. These findings establish a strong foundation for enzyme engineering and aim at developing efficient microplastic degradation.

biophysics↗

bioRxiv2026

Structural Insights and Inhibitor Discovery for Kyasanur Forest Disease Virus NS5 Methyltransferase

Kyasanur Forest Disease Virus (KFDV) NS5 methyltransferase (MTase) protein is the essential enzyme that is involved in the cap methylation of viral RNA, viral replication, and immune evasion, and therefore it is an important protein of interest for antiviral research and drug design. In the present work, we successfully resolved the three-dimensional crystal structures of KFDV NS5 MTase co-crystallised with SAH and GTP at resolutions of 2.2 [A] and 2.6 [A], respectively. In previous studies, HC (Herbacetin) and CAPE (Caffeic acid phenethyl ester) have shown inhibitory activity against SAM-dependent viral MTase. To evaluate the inhibitory potential of HC and CAPE against KFDV NS5 MTase, we have performed isothermal titration calorimetry (ITC) and tryptophan fluorescence spectroscopy (TFS) to validate protein interaction with target compounds. MTase inhibition assay was performed using capillary electrophoresis (CE) assays. Additionally, fluorescence polarisation (FP) confirmed RNA binding inhibition by CAPE and HC. Together, these experiments suggest that HC and CAPE are promising inhibitors against KFDV NS5 MTase and could potentially act as lead compounds to design broad-spectrum anti-Orthoflavivirus drugs.

molecular biology↗

bioRxiv2023

Using CRISPR/Cas9 to identify genes required for mechanosensory neuron development and function

Tunicates are marine, non-vertebrate chordates that comprise the sister group to the vertebrates. Most tunicates have a biphasic lifecycle that alternates between a swimming larva and a sessile adult. Recent advances have shed light on the neural basis for the tunicate larvas ability to sense a proper substrate for settlement and initiate metamorphosis. Work in the highly tractable laboratory model tunicate Ciona robusta suggests that sensory neurons embedded in the anterior papillae of transduce mechanosensory stimuli to trigger larval tail retraction and initiate the process of metamorphosis. Here, we take advantage of the low-cost and simplicity of Ciona by using tissue-specific CRISPR/Cas9-mediated mutagenesis to screen for genes potentially involved in mechanosensation and metamorphosis, in the context of an undergraduate "capstone" research course. This small screen revealed at least one gene, Vamp1/2/3, that appears crucial for the ability of the papillae to trigger metamorphosis. We also provide step-by-step protocols and tutorials associated with this course, in the hope that it might be replicated in similar CRISPR-based laboratory courses wherever Ciona are available.

developmental biology↗