Interplay between the RNA Chaperone Hfq, Small RNAs and Transcriptional Regulator OmpR Modulates Iron Homeostasis in the Enteropathogen .

Iron is both essential for and potentially toxic to bacteria, so the precise maintenance of iron homeostasis is necessary for their survival. Our previous study indicated that in the human enteropathogen , the regulator OmpR directly controls the transcription of the , and genes, encoding the ferric uptake repressor and two transporters of ferric siderophores, respectively. This study was undertaken to determine the significance of the RNA chaperone Hfq and the small RNAs OmrA and RyhB1 in the post-transcriptional control of the expression of these OmpR targets.

The Regulatory Circuit Underlying Downregulation of a Type III Secretion System in by Transcription Factor OmpR.

In a previous study, differential proteomic analysis was used to identify membrane proteins of the human enteropathogen , whose levels are influenced by OmpR, the transcriptional regulator in the two-component EnvZ/OmpR system. Interestingly, this analysis demonstrated that at 37 °C, OmpR negatively affects the level of over a dozen Ysc-Yop proteins, which constitute a type III secretion system (T3SS) that is essential for the pathogenicity of . Here, we focused our analysis on the role of OmpR in the expression and secretion of Yops (translocators and effectors).

The Regulator OmpR in Participates in Iron Homeostasis by Modulating Fur Level and Affecting the Expression of Genes Involved in Iron Uptake.

In this study, we found that the loss of OmpR, the response regulator of the two-component EnvZ/OmpR system, increases the cellular level of Fur, the master regulator of iron homeostasis in . Furthermore, we demonstrated that transcription of the gene from the YeP promoter is subject to negative OmpR-dependent regulation. Four putative OmpR-binding sites (OBSs) were indicated by in silico analysis of the promoter region, and their removal affected OmpR-dependent expression.

Urease Expression in Pathogenic Strains of Bio-Serotypes 2/O:9 and 1B/O:8 Is Differentially Regulated by the OmpR Regulator.

exhibits a dual lifestyle, existing as both a saprophyte and a pathogen colonizing different niches within a host organism. OmpR has been recognized as a regulator that controls the expression of genes involved in many different cellular processes and the virulence of pathogenic bacteria. Here, we have examined the influence of OmpR and varying temperature (26°C vs.

OmpR-Mediated Transcriptional Regulation and Function of Two Heme Receptor Proteins of Bio-Serotype 2/O:9.

We show that strain Ye9 (bio-serotype 2/O:9) utilizes heme-containing molecules as an iron source. The Ye9 genome contains two multigenic clusters, -1 and -2, encoding putative heme receptors HemR1 and HemR2, that share 62% amino acid identity. Expression of these proteins in an mutant defective in heme biosynthesis allowed this strain to use hemin and hemoglobin as a source of porphyrin.