The effects of PstR, a PadR family transcriptional regulatory factor, in Plesiomonas shigelloides are revealed by transcriptomics

Abstract

Background: Plesiomonas shigelloides is a gram-negative opportunistic pathogen associated with gastrointestinal and extraintestinal diseases in humans. There have been reports of specific functional genes in the study of P. shigelloides, but there are also many unknown genes that may play a role in P. shigelloides pathogenesis as global regulatory proteins or virulence factors. Results: In this study, we found a transcriptional regulator of the PadR family in P. shigelloides and named it PstR (GenBank accession number: EON87311.1), which is present in various pathogenic bacteria but whose function has rarely been reported. RNA sequencing (RNA-Seq) was used to analyze the effects of PstR on P. shigelloides, and the results indicated that PstR regulates approximately 9.83% of the transcriptome, which includes impacts on motility, virulence, and physiological metabolism. RNA-seq results showed that PstR positively regulated the expression of the flagella gene cluster, which was also confirmed by quantitative Real-Time Polymerase Chain Reaction (qRT-PCR) and lux assays. Meanwhile, the ΔpstR mutant strains lacked flagella and were non-motile, as confirmed by motility assays and transmission electron microscopy (TEM). Additionally, RNA-seq, qRT-PCR, and lux assays demonstrated that PstR also positively regulates T3SS expression, which aids in P. shigelloides' capacity to infect Caco-2 cells. Meanwhile, we also revealed that PstR negatively regulates fatty acid degradation and metabolism, as well as the regulatory relationship between PsrA, a regulator of fatty acid degradation and metabolism, and its downstream genes in P. shigelloides. Conclusions: Overall, we revealed the effects of PstR on motility, virulence, and physiological metabolism in P. shigelloides, which will serve as a foundation for future research into the intricate regulatory network of PstR in bacteria.