GTR Seminar
Date: July 29(Wed.), 2026,14:30-15:30
Venue: Science Bidg. G, G101
Speaker: Dr. Gaurav Sharma（Assistant Professor, Department of Biotechnology, IIT Hyderabad, India）
Title: Two chromosomes, Four Chemosensory systems: Genome-scale phylogenomics uncovers a novel chemosensory architecture in Vibrionales
Signal transduction is one of the most pertinent and survival-determining characteristics of bacteria. The complex microbial signal transduction mechanism, i.e., chemosensory system(CSS), is known to regulate bacterial motility and other cellular functions. This study investigates the diversity, distribution, and evolutionary dynamics of CSSs in family Vibrionales members, a group of bacteria with diverse ecological habitats. Using 116 curated representative genomes across 28 Vibrio clades and ~10,000 RefSeq/metagenomeassembled genomes, we characterized the chemosensory toolkit of Vibrionales. CheA-based phylogenetics and CSS architecture revealed four discrete CSS types: F6, F7, F9, and a novel lineage, F8. F6 is universally conserved on chromosome I and essential for flagellar motility, while F7, F8, and F9 show patchy distribution across replicons. We used CheA as a phylogenetic marker to infer evolutionary relationships among CSSs and classified methylaccepting chemotaxis proteins (MCPs) based on their heptad-repeat architecture. Structural analysis reveals conserved CheA folds despite sequence divergence, with lineage-specific domain insertions in F8 and F9. Ongoing work involves analyzing the flagellar gene clusters, functionally linked to CSS across Vibrionales. Collectively, this study reveals a two-tier chemosensory architecture within order Vibrionales, 1) a chromosomally stable F6 (motility), 2) overlaid by dynamically evolving F7, F8, and F9 accessory systems.
Contact: Seiji KOJIMA (ex.2993)