GSE167483
The polar flagellar transcriptional regulatory network in Vibrio campbellii deviates from known Vibrio species
Vibrio campbellii is a gram-negative bacterial pathogen that is both free-living and a pathogen of marine organisms and exhibits swimming motility via a single, polar flagellum. Swimming motility is a critical virulence factor in V. campbellii pathogenesis, and disruption of the flagellar motor significantly decreases host mortality. However, while V. campbelli encodes homologs of flagellar and chemotaxis genes conserved by other members of the Vibrionaceae, the regulatory network governing these genes have not been explored. We systematically deleted all 63 known flagellar and chemotaxis genes in V. campbellii and examined their effects on motility compared to their homologs in other Vibrios. We specifically focused on assessing the roles of the core flagellar regulators of the flagellar regulatory hierarchy established in other Vibrios: rpoN, flrA, flrC, and fliA.  Although V. campbellii transcription of flagellar and chemotaxis genes is governed by a multi-tiered regulatory hierarchy similar to other Vibrios, we observed two critical differences: the s54-dependent regulator FlrA is dispensable for motility, and Class II gene expression is independent of s54 regulation. Our genetic and phenotypic dissection of the V. campbellii flagellar regulatory network highlights the differences that have evolved in flagellar regulation across the Vibrionaceae. Overall design: RNA-Seq of cultures grown to OD600=1.0