CRP is an activator of Yersinia pestis biofilm formation that operates via a mechanism involving gmhA and waaAE-coaD.

gmhA encodes a phosphoheptose isomerase that catalyzes the biosynthesis of heptose, a conserved component of lipopolysaccharide (LPS). GmhA plays an important role in Yersinia pestis biofilm blockage in the flea gut. waaA, waaE, and coaD constitute a three-gene operon waaAE-coaD in Y. pestis. waaA encodes a transferase that is responsible for binding lipid-A to the core oligosaccharide of LPS. WaaA is a key determinant in Y. pestis biofilm formation, and the waaA expression is positively regulated by the two-component regulatory system PhoP/PhoQ. WaaE is involved in LPS modification and is necessary for Y. pestis biofilm production. In this study, the biofilm-related phenotypic assays indicate that the global regulator CRP stimulates Y. pestis biofilm formation in vitro and on nematodes, while it has no regulatory effect on the biosynthesis of the biofilm-signaling molecular 3ʹ,5ʹ-cyclic diguanosine monophosphate. Further gene regulation experiments disclose that CRP does not regulate the hms genes at the transcriptional level but directly promotes the gmhA transcription and indirectly activates the waaAE-coaD transcription through directly acting on phoPQ-YPO1632. Thus, it is speculated that CRP-mediated carbon catabolite regulation of Y. pestis biofilm formation depends on the CRP-dependent carbon source metabolic pathways of the biosynthesis, modification and transportation of biofilm exopolysaccharide

Omics strategies for revealing Yersinia pestis virulence

Omics has remarkably changed the way we investigate and understand life. Omics differs from traditional hypothesis-driven research because it is a discovery-driven approach. Mass datasets produced from omics-based studies require experts from different fields to reveal the salient features behind these data. In this review, we summarize omics-driven studies to reveal the virulence features of Yersinia pestis through genomics, trascriptomics, proteomics, interactomics, etc. These studies serve as foundations for further hypothesis-driven research and help us gain insight into Yersinia pestis pathogenesis

Intrinsic plasmids influence MicF-mediated translational repression of ompF in Yersinia pestis

Yersinia pestis, which is the causative agent of plague, has acquired exceptional pathogenicity potential during its evolution from Y. pseudotuberculosis. Two laterally acquired plasmids, namely, pMT1 and pPCP1, are specific to Y. pestis and are critical for pathogenesis and flea transmission. Small regulatory RNAs (sRNAs) commonly function as regulators of gene expression in bacteria. MicF, is a paradigmatic sRNA that acts as a post-transcriptional repressor through imperfect base pairing with the 5’-UTR of its target mRNA, ompF, in Escherichia coli. The high sequence conservation and minor variation in the RNA duplex of MicF-ompF has been reported in Yersinia. In this study, we utilized super-folder GFP reporter gene fusion to validate the post-transcriptional MicF-mediated regulation of target mRNA ompF in Y. pestis. Unexpectedly, upon MicF overexpression, the slightly upregulated expression of OmpF were found in the wild-type strain, which contradicted the previously established model. Interestingly, the translational repression of ompF target fusions was restored in the intrinsic plasmids-cured Y. pestis strain, suggesting intrinsic plasmids influence the MicF-mediated translational repression of ompF in Y. pestis. Further examination showed that plasmid pPCP1 is likely the main contributor to the reversal of MicF-mediated translational repression of ompF. It represents that the possible roles o

TyrR, the regulator of aromatic amino acid metabolism, is required for mice infection of Yersinia pestis

Yersinia pestis, the causative agent of plague, poses a serious health threat to rodents and human beings. TyrR is a transcriptional regulator that controls the metabolism of aromatic amino acids in Escherichia coli. In this paper, TyrR played an important role in Y. pestis virulence. Inactivation of tyrR did not seem to affect the in vitro growth of this organism, but resulted in at least 10,000-fold attenuation compared with the wild-type (WT) strain upon subcutaneous infection to mice. In addition, loads of tyrR mutant within mice livers and spleens significantly decreased compared with the WT strain. Transcriptome analysis revealed that TyrR, directly or indirectly, regulated 29 genes encoded on Y. pestis chromosome or plasmids under in vitro growth condition. Similar to the regulatory function of this protein in E. coli, five aromatic-pathway genes (aroF-tyrA, aroP, aroL, and tyrP) were significantly reduced upon deletion of the tyrR gene. Two genes (glnL and glnG) that encode sensory histidine kinase and regulator in a two-component regulatory system involved in nitrogen assimilation were downregulated in the tyrR mutant. Several genes encoding type III secretion proteins were transcribed by 2.0- to 4.2-fold in a tyrR mutant relative to the WT strain. Interestingly, the acid-stressed genes, hdeB and hdeD, were downregulated, and such downregulation partly accounted for the decrease in tolerance of the tyrR mutant under acidic conditions. In conclusion, regulation of TyrR in Y. pestis is similar to, but distinct from, that in E. coli. TyrR is a metabolic virulence determinant in Y. pestis that is important for extracellular survival and/or proliferation