title: The role of BmoR, a MarR Family Regulator, in the survival of Bacteroides fragilis during oxidative stress.
abstract: The intestinal opportunistic pathogen Bacteroides fragilis is among the most aerotolerant species of strict anaerobic bacteria and survives exposure to atmospheric oxygen for up to 72h. Under these circumstances, a strong oxygen stress response (OSR) mechanism is activated and the expression of as much as 45% of B. fragilis genes is altered. One of the most important regulators of this response is the product of the oxyR gene, but other regulation systems are in place during the OSR. The MarR family of transcriptional regulators has been shown to control several physiological events in bacteria, including response to stress conditions. In B. fragilis, at least three homologs of MarR regulators are present, one of which, bmoR, is upregulated during oxidative stress independently of oxyR. In this study, we demonstrate that the inactivation of the bmoR gene in B. fragilis diminishes its ability to withstand oxidative stress caused either by exposure to atmospheric oxygen or hydrogen peroxide. Recovery of growth rate on pre-oxidized media under anaerobiosis is slower than that observed in parental strain. Addition of hydrogen peroxide has a similar effect on the growth rate. Complementation of the mutant strain partially recovered the oxygen resistance phenotype, but the overexpression of the gene in the parental strain was also deleterious to a lesser extent. Our results indicate that BmoR has a role in the OSR in B. fragilis, particularly in the initial stages of oxygen exposure.
authors.affiliation: Laboratório de Biologia de Anaeróbios, Departamento de Microbiologia Médica, Instituto de Microbiologia Paulo de Góes/Universidade Federal do Rio de Janeiro - Rio de Janeiro/RJ, Brazil. Electronic address: feloteix@gmail.com.
authors.forename: Felipe Lopes
authors.initials: FL
authors.lastname: Teixeira
authors.forename: Deborah Nascimento Dos Santos
authors.initials: DN
authors.lastname: Silva
authors.forename: Heidi
authors.initials: H
authors.lastname: Pauer
authors.forename: Livia Queiroz
authors.initials: LQ
authors.lastname: Ferreira
authors.forename: Eliane de Oliveira
authors.initials: Ede O
authors.lastname: Ferreira
authors.forename: Regina Maria Cavalcanti Pilotto
authors.initials: RM
authors.lastname: Domingues
authors.forename: Leandro Araujo
authors.initials: LA
authors.lastname: Lobo
mesh_terms: D000693:Anaerobiosis; D001441:Bacteroides fragilis / Q000187:drug effects* / Q000235:genetics / Q000254:growth & development / Q000502:physiology*; D015964:Gene Expression Regulation, Bacterial; D055786:Gene Knockout Techniques; D005816:Genetic Complementation Test; D006801:Humans; D006861:Hydrogen Peroxide / Q000378:metabolism / Q000633:toxicity; D050296:Microbial Viability / Q000187:drug effects*; D018384:Oxidative Stress; D010100:Oxygen / Q000378:metabolism / Q000633:toxicity; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism*
chemical_list: D014157:Transcription Factors; D006861:Hydrogen Peroxide; D010100:Oxygen
keywords: Bacteroides fragilis; MarR; Oxidative stress