Feedback control of the pleiotropic regulators and H-NS antagonists LeuO and RcsB-BglJ in Escherichia coli

• Applicant: Professorin Dr. Karin Schnetz
• Subject Area: Metabolism, Biochemistry and Genetics of Microorganisms
• Term: from 2008 to 2016
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 86649608

H-NS has a major role in repression of horizontally acquired AT-rich DNA and of genes for responses to various stress conditions and changes in the environment associated with the host habitat. Silencing by H-NS is based on the formation of nucleoprotein complexes on AT-rich DNA, and is modulated and relieved locus specifically. In this project we wish to analyze a regulatory cascade that involves the LysR-type transcription factor LeuO and the LuxR-type transcription factors YjjQ and BglJ. LeuO and YjjQ are transcription factors important for virulence of Salmonella enterica and avian pathogenic Escherichia coli, respectively. LeuO, whose expression is H-NS-repressed and positively auto-regulated, counteracts the H-NS mediated repression of the yjjQ-bglJ operon. YjjQ and BglJ both interact with the response regulator RcsB of the Rcs membrane and peptidoglycan stress signaling system. The so far only known target gene of these proteins is the H-NS repressed bgl operon whose repression is relieved by the BglJ/RcsB heterodimer. The aims of the project are to characterize (i) the molecular mechanism underlying de-repression of the yjjQ-bglJ operon by LeuO and (ii) the role of BglJ and YjjQ in control of H-NS repressed and other loci and in their relation to the Rcs signal transduction system in commensal and pathogenic E.coli.

• DFG Programme: Research Grants