Browsing by Author "P. K. Satheeshkumar"

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Heterologous Expression, Purification, and Characterization of a High-Temperature Requirement A (HtrA) Protease Homologue from Leptospira
(Springer, 2025) Preeti Kumari; Garima Singh; Samarendra Kumar Singh; P. K. Satheeshkumar
Leptospirosis is a zoonotic disease affecting humans in the tropical and temperate regions. Considerably high mortality rate (60 per 1000 adult) and associated morbidity necessitate the need for efficient diagnostic and therapeutic approaches for this disease. Proteins that play crucial roles in the invasion/pathogenesis are potential candidates for the diagnosis/therapeutics. High temperature requirement A (HtrA) is a protein expressed by many pathogenic bacteria, important for their virulence and survival. In this study, we have amplified, cloned, and expressed one of the HtrA homologues (HtrA1) from Leptospira. The expressed recombinant HtrA was purified using Ni–NTA chromatography. Physicochemical characterization of the enzyme using azo-casein substrate showed the maximum activity at a temperature 42 °C and pH 7. While Mn2+ showed significant positive effect, all the other tested metals inhibited the enzymatic activity, sometimes up to 97% as in the case of Cu2+. All the protease inhibitors inhibited the enzymatic activity with PMSF having maximum efficiency. The host cells expressing HtrA showed growth inhibition in a time-bound manner. Docking analysis identified the crucial amino acids involved in the interaction with cell junction proteins like E-cadherin, occludin, claudin-8, and desmoglein-2. Treating adherent mammalian cells with the recombinant protein showed the disruption of cell adherence, and the western analysis of the protein samples collected from the same experiment indicated the cell junction protein cleavage when probed with anti-E-cadherin antibody. © The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature 2025.
Identification of inhibitors for the collagenase of Leptospira interrogans through docking and molecular simulation
(Springer Nature, 2025) Vikram Kumar; Selvaa Kumar Chellasamy; Nagesh Srikakulam; P. K. Satheeshkumar; Madathiparambil Gopalakrishnan Madanan; Jebasingh Tennyson
Leptospirosis is a neglected tropical zoonotic infection caused by Leptospira interrogans. Collagenase protein is a virulence factor for pathogenic L. interrogans, which facilitates its invasion into Homo sapiens. There is a paucity of chemical compounds that can inhibit the colonisation and infiltration of the pathogen into the host. We looked at the modelled collagenase from L. interrogans for docking studies with ligands and simulations in this study. Based on the results, 4-(3,4-Dihydroxyphenyl)-2-hydroxy-1H-phenalen-1-one, obtained from Musella lasiocarpa (Chinese Dwarf Banana) basically a nutraceuticals and terpene deoxyherqueinone from tea plants and Penicillium herquei was identified as having drug-like properties and demonstrated better binding within the active site pocket of collagenase during the course of protein–ligand docking and simulation. This selected phytochemical can be further taken up for wet-lab-based validation to provide a potential drug to curb this waterborne disease in the near future. © Indian National Science Academy 2024.
Plant Communication: How Plants Converse and Cope Up
(Springer, 2025) Aakanksha Singh; P. K. Satheeshkumar
The sessile nature of plants forces them to coexist with and adapt to both biotic and abiotic factors present around them for survival. Recent findings indicate that plants communicate with their neighbours, which is important for their survival and reproduction. Even though they are known to respond to environmental cues and mechanical stimulations like gravity, light, water, temperature, pressure, and touch, a response to another plant’s signal is inconspicuous. Research on plant communication has revealed many ways plants communicate with themselves and even with members of different kingdoms. Plants exposed to biotic or abiotic stresses emit signals that are perceived by neighboring, unstressed plants, thereby triggering defense responses comparable to those induced in the originally challenged individuals. The signals developed in response to an encounter include volatile organic compounds (VOCs), electrical signals, proteins, peptides, amino acids, microRNAs, hormones, and acoustic signals. Major adaptive responses are reported in plants at the genome level due to the intra- and inter-kingdom communication of plants. While several recent reviews focus extensively on specific topics such as VOC-mediated or mycorrhiza-mediated interactions, other equally important aspects relevant to plant communication have been insignificantly represented. This review aims to provide a comprehensive overview of all known mechanisms through which plants interact with their surroundings. Special emphasis has been placed on highlighting topics that have received less attention in the literature, while offering detailed insights into already well-established areas. © The New York Botanical Garden 2025.