title: Control ofgdhRExpression inNeisseria gonorrhoeaevia Autoregulation and a Master Repressor (MtrR) of a Drug Efflux Pump Operon.
abstract: The MtrCDE efflux pump ofNeisseria gonorrhoeaecontributes to gonococcal resistance to a number of antibiotics used previously or currently in treatment of gonorrhea, as well as to host-derived antimicrobials that participate in innate defense. Overexpression of the MtrCDE efflux pump increases gonococcal survival and fitness during experimental lower genital tract infection of female mice. Transcription ofmtrCDEcan be repressed by the DNA-binding protein MtrR, which also acts as a global regulator of genes involved in important metabolic, physiologic, or regulatory processes. Here, we investigated whether a gene downstream ofmtrCDE, previously annotatedgdhRinNeisseria meningitidis, is a target for regulation by MtrR. In meningococci, GdhR serves as a regulator of genes involved in glucose catabolism, amino acid transport, and biosynthesis, includinggdhA, which encodes an l-glutamate dehydrogenase and is located next togdhRbut is transcriptionally divergent. We report here that inN. gonorrhoeae, expression ofgdhRis subject to autoregulation by GdhR and direct repression by MtrR. Importantly, loss of GdhR significantly increased gonococcal fitness compared to a complemented mutant strain during experimental murine infection. Interestingly, loss of GdhR did not influence expression ofgdhA, as reported for meningococci. This variance is most likely due to differences in promoter localization and utilization between gonococci and meningococci. We propose that transcriptional control of gonococcal genes through the action of MtrR and GdhR contributes to fitness ofN. gonorrhoeaeduring infection.IMPORTANCEThe pathogenicNeisseriaspecies are strict human pathogens that can cause a sexually transmitted infection (N. gonorrhoeae) or meningitis or fulminant septicemia (N. meningitidis). Although they share considerable genetic information, little attention has been directed to comparing transcriptional regulatory systems that modulate expression of their conserved genes. We hypothesized that transcriptional regulatory differences exist between these two pathogens, and we used thegdhlocus as a model to test this idea. For this purpose, we studied two conserved genes (gdhRandgdhA) within the locus. Despite general conservation of thegdhlocus in gonococci and meningococci, differences exist in noncoding sequences that correspond to promoter elements or potential sites for interacting with DNA-binding proteins, such as GdhR and MtrR. Our results indicate that implications drawn from studying regulation of conserved genes in one pathogen are not necessarily translatable to a genetically related pathogen.
authors.affiliation: Laboratories of Bacterial Pathogenesis, VA Medical Center, Decatur, Georgia, USA.|Department of Microbiology and Immunology, Emory University School of Medicine, Atlanta, Georgia, USA.
authors.forename: Corinne E
authors.initials: CE
authors.lastname: Rouquette-Loughlin
authors.affiliation: Laboratories of Bacterial Pathogenesis, VA Medical Center, Decatur, Georgia, USA.|Department of Microbiology and Immunology, Emory University School of Medicine, Atlanta, Georgia, USA.
authors.forename: Yaramah M
authors.initials: YM
authors.lastname: Zalucki
authors.affiliation: Laboratories of Bacterial Pathogenesis, VA Medical Center, Decatur, Georgia, USA.|Department of Microbiology and Immunology, Emory University School of Medicine, Atlanta, Georgia, USA.
authors.forename: Vijaya L
authors.initials: VL
authors.lastname: Dhulipala
authors.affiliation: Laboratories of Bacterial Pathogenesis, VA Medical Center, Decatur, Georgia, USA.|Department of Microbiology and Immunology, Emory University School of Medicine, Atlanta, Georgia, USA.
authors.forename: Jacqueline T
authors.initials: JT
authors.lastname: Balthazar
authors.affiliation: Departments of Pharmacology and Microbiology and Immunology, University of North Carolina, Chapel Hill, North Carolina, USA.
authors.forename: Raúl G
authors.initials: RG
authors.lastname: Doyle
authors.affiliation: Departments of Pharmacology and Microbiology and Immunology, University of North Carolina, Chapel Hill, North Carolina, USA.
authors.forename: Robert A
authors.initials: RA
authors.lastname: Nicholas
authors.affiliation: Department of Microbiology and Immunology, F. Edward Hébert School of Medicine, Uniformed Services University, Bethesda, Maryland, USA.
authors.forename: Afrin A
authors.initials: AA
authors.lastname: Begum
authors.affiliation: Department of Microbiology and Immunology, F. Edward Hébert School of Medicine, Uniformed Services University, Bethesda, Maryland, USA.
authors.forename: Erica L
authors.initials: EL
authors.lastname: Raterman
authors.affiliation: Department of Microbiology and Immunology, F. Edward Hébert School of Medicine, Uniformed Services University, Bethesda, Maryland, USA.
authors.forename: Ann E
authors.initials: AE
authors.lastname: Jerse
authors.affiliation: Laboratories of Bacterial Pathogenesis, VA Medical Center, Decatur, Georgia, USA wshafer@emory.edu.|Department of Microbiology and Immunology, Emory University School of Medicine, Atlanta, Georgia, USA.|Emory Antibiotic Resistance Center, Emory University School of Medicine, Atlanta, Georgia, USA.
authors.forename: William M
authors.initials: WM
authors.lastname: Shafer
mesh_terms: D000818:Animals; D001426:Bacterial Proteins / Q000378:metabolism*; D004195:Disease Models, Animal; D017353:Gene Deletion; D015964:Gene Expression Regulation, Bacterial; D006069:Gonorrhea / Q000382:microbiology; D006706:Homeostasis; D051379:Mice; D009344:Neisseria gonorrhoeae / Q000235:genetics*; D009876:Operon; D012097:Repressor Proteins / Q000378:metabolism*; D014774:Virulence
chemical_list: D001426:Bacterial Proteins; D012097:Repressor Proteins; C087450:mtrR protein, Neisseria gonorrhoeae
keywords: efflux pumps; gonococci; physiology; transcription