RT Journal Article SR Electronic(1) A1 Brzostek, Katarzyna A1 Brzóstkowska, Marta A1 Bukowska, Iwona A1 Karwicka, Ewa A1 Raczkowska, AdriannaYR 2007 T1 OmpR negatively regulates expression of invasin in Yersinia enterocolitica JF Microbiology, VO 153 IS 8 SP 2416 OP 2425 DO https://doi.org/10.1099/mic.0.2006/003202-0 PB Microbiology Society, SN 1465-2080, AB Invasin, the major adhesion and invasion factor of Yersinia enterocolitica, is encoded by the inv gene, which is regulated by growth phase and in response to a variety of environmental conditions such as temperature, pH and osmolarity. So far, three proteins, RovA, H-NS and YmoA, have been identified as factors regulating the expression of the inv gene in enteropathogenic Yersinia. Here, data from inv′ : : lacZYA chromosomal gene fusion studies are presented indicating that OmpR, the response regulator of the EnvZ/OmpR two-component system, acts to negatively regulate inv expression at the transcriptional level at 25 °C, and that high osmolarity enhances the inhibitory effect of this protein. In a strain lacking OmpR the expression of inv at 25 °C was increased sixfold, but at 37 °C, a temperature known to repress inv expression, this effect was not observed, suggesting that temperature regulation of inv is OmpR-independent. Furthermore, the expression of inv in the ompR background was no longer responsive to increased osmolarity. Complementation with the active ompR allele restored wild-type inv expression in the ompR mutant. In silico analysis of the Y. enterocolitica O : 9 inv promoter sequence revealed the presence of an OmpR consensus binding site located in the −15 to −33 region. OmpR was able to specifically bind to a fragment of the inv promoter containing this putative binding site in electrophoretic mobility shift assays. Thus, OmpR seems to be a repressor of inv in Y. enterocolitica. , UL https://www.microbiologyresearch.org/content/journal/micro/10.1099/mic.0.2006/003202-0