YhjC is a novel transcriptional regulator required for Shigella flexneri virulence

Abstract

Shigella is an intracellular pathogen that primarily infects the human colon and causes shigellosis. Shigella virulence relies largely on the type III secretion system (T3SS) and secreted effectors. VirF, the master Shigella virulence regulator, is essential for the expression of T3SS-related genes. In this study, we found that YhjC, a LysR-type transcriptional regulator, is required for Shigella virulence through activating the transcription of virF. Pathogenicity of the yhjC mutant, including colonization in the colons of guinea pigs as well as its ability for host cell adhesion and invasion, was significantly lowered. Expression levels of virF and nearly all VirF-dependent genes were downregulated by yhjC deletion, indicating that YhjC can activate virF transcription. Electrophoretic mobility shift assay analysis demonstrated that YhjC could bind directly to the virF promoter region. Therefore, YhjC is a novel virulence regulator that positively regulates the virF expression and promotes Shigella virulence. Additionally, genome-wide expression analysis identified the presence of other genes in the large virulence plasmid and a genome exhibiting differential expression in response to yhjC deletion, with 169 downregulated and 99 upregulated genes, indicating that YhjC also functioned as a global regulatory factor.

The Sub-Inhibitory Effect of Azithromycin and Ciprofloxacin on VirF Gene Expression in Enteroinvasive Escherichia Coli and Shigella Flexneri

“…The factors that have effect on the expression of the yhjC gene are unknown, however, it has been observed that expression of this gene increases, when the temperature rises from 30 to 37 degrees. These ndings increase the prospect that this gene is under control of a twocomponent regulation system CpxA/R (34). In the present study, temperature, pH, and osmolarity for all antibiotic-treated and untreated samples were equal, thus, the probability that Sub-MICs of antibiotics alter virF expression via CpxA/R, is diminished.…”

Novel Insight of Transcription Factor PtrA on Pathogenicity and Carbapenems Resistance in Pseudomonas aeruginosa

“…The adhesion and invasion capacities of each strain were measured according to the previous method. 35 , 36 Briefly, overnight cultures of each strain were subcultured to the OD 600 of 1. The culture medium underwent centrifugation at 4000 ×g for 5 min, and fresh DMEM was introduced to suspend the cell pellets.…”

Nitrate Utilization Promotes Systemic Infection of Salmonella Typhimurium in Mice

“…Salmonella Typhimurium ATCC 14028s was used as the wild-type (WT) strain in this study. The mutant strain was generated using the λ Red recombinase system supported by the pSim17 plasmid (blastidin-resistant) encoding three proteins (Exo, Beta, and Gam) that are required for homologous recombination [42]. First, a WT strain harboring the pSim17 plasmid was established through electrotransformation.…”