title: Oxidative stress enhances the expression of sulfur assimilation genes: preliminary insights on the Enterococcus faecalis iron-sulfur cluster machinery regulation.
abstract: The Firmicutes bacteria participate extensively in virulence and pathological processes. Enterococcus faecalis is a commensal microorganism; however, it is also a pathogenic bacterium mainly associated with nosocomial infections in immunocompromised patients. Iron-sulfur [Fe-S] clusters are inorganic prosthetic groups involved in diverse biological processes, whose in vivo formation requires several specific protein machineries. Escherichia coli is one of the most frequently studied microorganisms regarding [Fe-S] cluster biogenesis and encodes the iron-sulfur cluster and sulfur assimilation systems. In Firmicutes species, a unique operon composed of the sufCDSUB genes is responsible for [Fe-S] cluster biogenesis. The aim of this study was to investigate the potential of the E. faecalis sufCDSUB system in the [Fe-S] cluster assembly using oxidative stress and iron depletion as adverse growth conditions. Quantitative real-time polymerase chain reaction demonstrated, for the first time, that Gram-positive bacteria possess an OxyR component responsive to oxidative stress conditions, as fully described for E. coli models. Likewise, strong expression of the sufCDSUB genes was observed in low concentrations of hydrogen peroxide, indicating that the lowest concentration of oxygen free radicals inside cells, known to be highly damaging to [Fe-S] clusters, is sufficient to trigger the transcriptional machinery for prompt replacement of [Fe-S] clusters.
authors.affiliation: Laboratório de Cocos Gram-positivos e Microbiologia Molecular, Departamento de Microbiologia, Universidade Federal de Ciências da Saúde de Porto Alegre, Porto Alegre, RS, Brasil.
authors.forename: Gustavo Pelicioli
authors.initials: GP
authors.lastname: Riboldi
authors.affiliation: Universidade Federal do Rio Grande do Sul, Porto Alegre, RS, Brasil.
authors.forename: Christine Garcia
authors.initials: CG
authors.lastname: Bierhals
authors.affiliation: Instituto de Ciência e Tecnologia de Alimentos, Universidade Federal do Rio Grande do Sul, Porto Alegre, RS, Brasil.
authors.forename: Eduardo Preusser de
authors.initials: EP
authors.lastname: Mattos
authors.affiliation: Universidade Federal do Rio Grande do Sul, Porto Alegre, RS, Brasil.
authors.forename: Ana Paula Guedes
authors.initials: AP
authors.lastname: Frazzon
authors.affiliation: Laboratório de Cocos Gram-positivos e Microbiologia Molecular, Departamento de Microbiologia, Universidade Federal de Ciências da Saúde de Porto Alegre, Porto Alegre, RS, Brasil.
authors.forename: Pedro Alves
authors.initials: PA
authors.lastname: d'Azevedo
authors.affiliation: Instituto de Ciência e Tecnologia de Alimentos, Universidade Federal do Rio Grande do Sul, Porto Alegre, RS, Brasil.
authors.forename: Jeverson
authors.initials: J
authors.lastname: Frazzon
mesh_terms: D053898:Biosynthetic Pathways; D013293:Enterococcus faecalis / Q000378:metabolism*; D007506:Iron-Sulfur Proteins / Q000096:biosynthesis / Q000235:genetics*; D008958:Models, Molecular; D018384:Oxidative Stress; D060888:Real-Time Polymerase Chain Reaction; D013379:Substrate Specificity
chemical_list: D007506:Iron-Sulfur Proteins