Transcriptional Regulation Between the Two Global Regulators RovA and CRP in Yersinia pestis biovar Microtus

Altered Yersinia pestis virulence is associated with the small regulatory RNA HmsA encoded on the plasmid pPCP1

Aim: The aim of this study was to access the effect of HmsA, a 65-nt small regulatory RNA encoded by the pPCP1 plasmid, on Yersinia pestis virulence. Materials & methods: Survival and the competition index were determined in mice infected with wild-type Y. pestis and an hmsA deletion mutant. RNA-seq was used to identify HmsA-regulated genes. Results: HmsA deletion enhanced Y. pestis virulence. However, there was no overlap between 18 upregulated genes associated with pathogenicity and potential direct HmsA targets, based on gene expression screening after HmsA-pulse overexpression. Conclusion: HmsA inhibits Y. pestis virulence, but this effect may be mediated by indirect effects on pathogenesis, iron homeostasis and/or other cellular processes.

Identification and study of InV as an inverse autotransporter family representative in Edwardsiella piscicida

Invasins and intimins, members of virulence-related adhesin family which is involved in attachment and adherence to epithelial cells during infection, are found in various pathogens. These pathogens can attach to enterocytes and lead to the formation of a pedestal-like structure. Invasins and intimins belong to type Ve secretion systems, and the N-terminal β-barrel domain acts as a translocation pore to secrete the C-terminal passenger domain. However, the relationship between invasins/intimins and type III secretion system (T3SS) has been poorly studied. Based on the transposon insertion mutant library of Edwardsiella piscicida, we got a transposon insertion mutant with significant T3SS defect and identified the mutated gene ETAE_0323 (named inV later). This gene encoded a protein with 2359 amino acid residues and was predicted to be an invasin. To study the relationship between InV and T3SS, strains with N-terminus or C-terminus deleted InV fragments were made. However, none of them was able to copy the phenotype of the transposon insertion mutant previously identified. The localization of InV in ΔT3SS strain was not significantly different from WT, suggesting that the T3SS defect in the transposon insertion mutant was likely to be caused by polar effect. Nevertheless, depletion of inV still showed dramatic internalization and virulence defect in HeLa cell and zebrafish model, respectively, suggesting InV as a virulence related protein.