title: GyrA interacts with MarR to reduce repression of the marRAB operon in Escherichia coli.
abstract: Bacterial two-hybrid studies of randomly cloned Escherichia coli DNA identified a physical interaction between GyrA, subunit A of gyrase, and MarR, a repressor of the marRAB operon. GyrA-His immobilized on Ni-nitrilotriacetic acid (NiNTA) resin bound MarR, while MarR alone did not bind. GyrA interfered with MarR binding to marO, as detected by electrophoretic mobility assays. In a strain bearing the marRAB operon and a marO-lacZ reporter, overexpression of GyrA increased LacZ activity, indicating decreased repression of marO-lacZ by MarR. These results were confirmed by an increased survival of cells treated with quinolones and other antibiotics when GyrA was overexpressed. This work, like a previous study examining TktA (12), shows that unrelated proteins can regulate MarR activity. The findings reveal an unexpected regulatory function of GyrA in antibiotic resistance.
authors.affiliation: Center for Adaptation Genetics and Drug Resistance, Department of Molecular Biology and Microbiology, Tufts University School of Medicine, Boston, MA 02111, USA.
authors.forename: Francis
authors.initials: F
authors.lastname: Domain
authors.forename: Stuart B
authors.initials: SB
authors.lastname: Levy
mesh_terms: D019677:Artificial Gene Fusion; D027081:DNA Gyrase / Q000378:metabolism*; D004926:Escherichia coli / Q000378:metabolism*; D029968:Escherichia coli Proteins / Q000378:metabolism*; D015964:Gene Expression Regulation, Bacterial; D017930:Genes, Reporter; D009876:Operon; D011485:Protein Binding; D025941:Protein Interaction Mapping; D012097:Repressor Proteins / Q000378:metabolism*; D020798:Two-Hybrid System Techniques; D001616:beta-Galactosidase / Q000235:genetics / Q000378:metabolism
chemical_list: D029968:Escherichia coli Proteins; C080004:MarR protein, E coli; D012097:Repressor Proteins; D001616:beta-Galactosidase; D027081:DNA Gyrase