Vibrio parahaemolyticus VtrA is a membrane-bound regulator and is activated via oligomerization

• Published in: PloS one Vol. 12; no. 11; p. e0187846
• Main Authors: Okada, Ryu, Matsuda, Shigeaki, Iida, Tetsuya
• Format: Journal Article
• Language: English
• Published: United States Public Library of Science 17-11-2017; Public Library of Science (PLoS)
• Subjects: Activation; Bacterial infections; Bile; Binding; Biology and Life Sciences; Causes of; Chemical bonds; Cholera; Deoxyribonucleic acid; Development and progression; Dimerization; DNA; E coli; Escherichia coli; Gastroenteritis; Gene expression; Genetic aspects; Genetic engineering; Homology; Infections; Leucine; Leucine zipper proteins; Medicine and Health Sciences; Membrane proteins; N-Terminus; Oligomerization; Oligomers; Pathogenesis; Pathogenicity; Pathogens; Physiological aspects; Plasmids; Polyamide-imides; Proteins; Regulators; Secretion; Signal transduction; Transcription activation; Transcription factors; Vibrio; Vibrio cholerae; Vibrio parahaemolyticus; Virulence; Virulence (Microbiology); Water-borne diseases; Waterborne diseases; Yeast; Japan
• ISSN: 1932-6203; 1932-6203
• DOI: 10.1371/journal.pone.0187846

Vibrio parahaemolyticus is a Gram-negative pathogen that causes food-borne gastroenteritis. A major virulence determinant of the organism is a type III secretion system (T3SS2) encoded on a pathogenicity island, Vp-PAI. Vp-PAI gene expression is regulated by two transcriptional regulators, VtrA and VtrB, whose N-terminal regions share homology with an OmpR-family DNA-binding domain. VtrA activates the gene expression of VtrB, which in turn activates Vp-PAI gene expression; however, the mechanism of this transcriptional activation by VtrA is not well understood. In this study, we determined that VtrA is a membrane protein with a transmembrane (TM) domain, which was required for its transcriptional regulatory activity. Although the N-terminal region of VtrA alone is insufficient for its transcriptional regulatory activity, forced oligomerization using the leucine-zipper dimerization domain of yeast GCN4 conferred transcriptional regulatory activity and a greater affinity for the promoter region of vtrB. A ToxR-based assay demonstrated that VtrA oligomerizes in vivo. We also showed that bile, a host-derived activator of VtrA, induces the oligomerization of VtrA, which requires the C-terminal domain. The promoter region of vtrB contained repetitive T-rich DNA elements, which are important for vtrB transcriptional activation and are conserved among T3SS2-possessing Vibrio species. These findings propose that VtrA is active as oligomers, which may facilitate its N-terminus binding the target DNA, thus enhancing its transcriptional regulatory activity.