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

Abstract

Fast response to environmental changes plays a key role in the transmission and pathogenesis of Yersinia enterocolitica. Osmoregulated periplasmic glucans (OPGs) are known to be involved in environmental perception of several Enterobacteriaceae pathogens; however, the biological function of OPGs in Y. enterocolitica is still unclear. In this study, we investigated the role of OPGs in Y. enterocolitica by deleting the opgGH operon encoding enzymes responsible for OPGs biosynthesis. Complete loss of OPGs in the opgGH mutant resulted in decreased motility, c-di-GMP production, biofilm formation and smaller cell size, whereas the overproduction of OPGs through restoration of opgGH expression promoted c-di-GMP/biofilm production and increased antibiotic resistance of Y. enterocolitica. Gene expression analysis revealed that opgGH deletion reduced transcription of flhDC, ftsAZ, hmsT and hmsHFRS genes regulated by the Rcs phosphorelay system, whereas additional deletion of rcs family genes (rcsF, rcsC, or rcsB) 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 flhDC, hmsHFRS, and hmsT. However, deletion of genes encoding the EnvZ/OmpR phosphorelay downregulated the flhDC, hmsHFRS and hmsT 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 Y. enterocolitica. 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 Y. enterocolitica.

Fur Represses Vibrio cholerae Biofilm Formation via Direct Regulation of vieSAB, cdgD, vpsU, and vpsA-K Transcription

“…The intracellular c-di-GMP concentration was measured as previously described (Meng et al, 2020). Briefly, the third-round of cultivated bacterial cells was 50-fold diluted, respectively, into 2 ml of fresh LB broth, LB supplemented with 100 µM DP, and LB supplemented with 40 µM FeSO 4 in a 5-ml glass tube and allowed to grow at 30 • C with shaking at 200 rpm to an OD 600 = 0.6∼0.8.…”

Rcs Phosphorelay Responses to Truncated Lipopolysaccharide-Induced Cell Envelope Stress in Yersinia enterocolitica

“…Our previous data demonstrated that the Rcs phosphorelay represses flhDC, hmsHFRS, and hmsT in Y. enterocolitica [10,34]. The flhDC operon encodes the master regulator of flagella biosynthesis [10].…”

“…Our previous data demonstrated that the Rcs phosphorelay represses flhDC, hmsHFRS, and hmsT in Y. enterocolitica [10,34]. The flhDC operon encodes the master regulator of flagella biosynthesis [10]. hmsHFRS and hmsT are genes involved in biofilm formation, of which hmsHFRS required for the biosynthesis of poly-β-1,6-N-acetylglucosamine exopolysaccharide and hmsT encoding diguanylate cyclase is essential for cyclic dimeric guanosine monophosphate (c-di-GMP) biosynthesis [35].…”

“…Encountered stresses include desiccation, changing osmotic stress, temperature fluctuations, and exposure to cationic antimicrobial peptides [8,9]. Therefore, Y. enterocolitica transitions through a variety of environments and must respond to these envelope stresses with appropriate gene expression regulation to promote survival and growth within host tissues [9,10].…”

“…Similarly, in a series of mutant strains of E. coli K12 that knocked out the core polysaccharide transferase gene in the waa gene cluster, Ren and colleagues found that only the ∆waaF strain might be sensed by the Rcs phosphorelay, leading to the production of colanic acid [23]. Although the Rcs system is involved in envelope stress responses and regulates various physiological behaviors of Y. enterocolitica [8,10], whether it can sense the truncated LPS in Y. enterocolitica is still unclear.…”