AUTHOR=Gu Dan , Zhang Youkun , Wang Kangru , Li Mingzhu , Jiao Xinan 

TITLE=Characterization of the RpoN regulon reveals the regulation of motility, T6SS2 and metabolism in Vibrio parahaemolyticus

JOURNAL=Frontiers in Microbiology

VOLUME=13

YEAR=2022

URL=https://www.frontiersin.org/journals/microbiology/articles/10.3389/fmicb.2022.1025960

DOI=10.3389/fmicb.2022.1025960

ISSN=1664-302X

ABSTRACT=<p><italic>Vibrio parahaemolyticus</italic> is a foodborne pathogen that can colonize the small intestine of the host and cause diarrhea. The alternative sigma factor RpoN plays a vital role in regulating motility, carbon utilization and affects host colonization in <italic>V. parahaemolyticus</italic> RIMD2210633. In this study, transcriptome and phenotypic analysis further expanded our understanding of the RpoN regulon in <italic>V. parahaemolyticus</italic>. A deletion mutant of <italic>rpoN</italic> (Δ<italic>rpoN</italic>) was subjected to RNA-seq for systemic identification of the RpoN-controlled genes. Compared with the wild-type (WT), 399 genes were differentially expressed in the Δ<italic>rpoN</italic> strain. Moreover, 264 genes were down-regulated in the Δ<italic>rpoN</italic> strain, including those associated with nitrogen utilization (<italic>VP0118</italic>), glutamine synthetase (<italic>VP0121</italic>), formate dehydrogenase (<italic>VP1511</italic> and <italic>VP1513</italic>-<italic>VP1515</italic>), quorum sensing (<italic>opaR</italic> and <italic>luxZ</italic>), polar flagellar systems, and type VI secretion system 2 (T6SS2). Quantitative real-time reverse transcription PCR (qRT-PCR) and electrophoretic mobility shift assay (EMSA) further confirmed that RpoN could directly bind to the promoters of these genes associated with polar flagellar systems (<italic>flgB</italic> and <italic>fliE</italic>), lateral flagellar systems (<italic>flgB2</italic> and <italic>lafA</italic>), T6SS2 (<italic>hcp2</italic> and <italic>VPA1044</italic>) and glutamine synthetase (<italic>VP0121</italic>), and then positively regulate the expression of these systems. A RpoN-binding motif was identified in <italic>V. parahaemolyticus</italic> using the MEME suite and verified by the EMSA. Besides, the deletion of <italic>rpoN</italic> caused a significant decrease in hemolytic activity, adhesion, and cytotoxicity. Our results provide new cues to better understand the regulatory networks of RpoN protein to motility, T6SS2, and metabolism in <italic>V. parahaemolyticus</italic>.</p>