AUTHOR=Meng Jiao , Huang Can , Huang Xiaoning , Liu Dingyu , Han Beizhong , Chen Jingyu 

TITLE=Osmoregulated Periplasmic Glucans Transmit External Signals Through Rcs Phosphorelay Pathway in Yersinia enterocolitica

JOURNAL=Frontiers in Microbiology

VOLUME=11

YEAR=2020

URL=https://www.frontiersin.org/journals/microbiology/articles/10.3389/fmicb.2020.00122

DOI=10.3389/fmicb.2020.00122

ISSN=1664-302X

ABSTRACT=<p>Fast response to environmental changes plays a key role in the transmission and pathogenesis of <italic>Yersinia enterocolitica</italic>. Osmoregulated periplasmic glucans (OPGs) are known to be involved in environmental perception of several <italic>Enterobacteriaceae</italic> pathogens; however, the biological function of OPGs in <italic>Y. enterocolitica</italic> is still unclear. In this study, we investigated the role of OPGs in <italic>Y. enterocolitica</italic> by deleting the <italic>opgGH</italic> operon encoding enzymes responsible for OPGs biosynthesis. Complete loss of OPGs in the Δ<italic>opgGH</italic> mutant resulted in decreased motility, c-di-GMP production, biofilm formation and smaller cell size, whereas the overproduction of OPGs through restoration of <italic>opgGH</italic> expression promoted c-di-GMP/biofilm production and increased antibiotic resistance of <italic>Y. enterocolitica</italic>. Gene expression analysis revealed that <italic>opgGH</italic> deletion reduced transcription of <italic>flhDC</italic>, <italic>ftsAZ</italic>, <italic>hmsT</italic> and <italic>hmsHFRS</italic> genes regulated by the Rcs phosphorelay system, whereas additional deletion of <italic>rcs</italic> family genes (<italic>rcsF</italic>, <italic>rcsC</italic>, or <italic>rcsB</italic>) reversed this effect and restored motility and c-di-GMP/biofilm production but further reduced cell size. Furthermore, disruption of the Rcs phosphorelay increased the motility and promoted the induction of biofilm and c-di-GMP production regulated by OPGs through upregulating the expression of <italic>flhDC</italic>, <italic>hmsHFRS</italic>, and <italic>hmsT</italic>. However, deletion of genes encoding the EnvZ/OmpR phosphorelay downregulated the <italic>flhDC</italic>, <italic>hmsHFRS</italic> and <italic>hmsT</italic> expression, leading to the decreased motility and prevented the induction of biofilm and c-di-GMP production regulated by OPGs. These results indicated that Rcs phosphorelay had the effect on OPGs-mediated functional responses in <italic>Y. enterocolitica</italic>. Our findings disclose part of the biological role of OPGs and the underlying molecular mechanisms associated with Rcs system in the regulation of the pathogenic phenotype in <italic>Y. enterocolitica.</italic></p>