The Regulator OmpR in <i>Yersinia enterocolitica</i> Participates in Iron Homeostasis by Modulating Fur Level and Affecting the Expression of Genes Involved in Iron Uptake

• Main Authors: Karolina Jaworska, Marta Ludwiczak, Emilia Murawska, Adrianna Raczkowska, Katarzyna Brzostek
• Format: Article
• Language: English
• Published: MDPI AG 2021-02-01
• Series: International Journal of Molecular Sciences
• Subjects: <i>Yersinia enterocolitica</i>; OmpR regulator; Fur repressor; iron homeostasis; <i>fecA</i>; <i>fepA</i>
• Online Access: https://www.mdpi.com/1422-0067/22/3/1475

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 <i>Y. enterocolitica</i>. Furthermore, we demonstrated that transcription of the <i>fur</i> gene from the YeP<i>fur</i> promoter is subject to negative OmpR-dependent regulation. Four putative OmpR-binding sites (OBSs) were indicated by in silico analysis of the <i>fur</i> promoter region, and their removal affected OmpR-dependent <i>fur</i> expression. Moreover, OmpR binds specifically to the predicted OBSs which exhibit a distinct hierarchy of binding affinity. Finally, the data demonstrate that OmpR, by direct binding to the promoters of the <i>fecA</i>, <i>fepA</i> and <i>feoA</i> genes, involved in the iron transport and being under Fur repressor activity, modulates their expression. It seems that the negative effect of OmpR on <i>fecA</i> and <i>fepA</i> transcription is sufficient to counteract the indirect, positive effect of OmpR resulting from decreasing the Fur repressor level. The expression of <i>feoA</i> was positively regulated by OmpR and this mode of action seems to be direct and indirect. Together, the expression of <i>fecA</i>, <i>fepA</i> and <i>feoA</i> in <i>Y. enterocolitica</i> has been proposed to be under a complex mode of regulation involving OmpR and Fur regulators.