title: The Herbaspirillum seropedicae SmR1 Fnr orthologs controls the cytochrome composition of the electron transport chain.
abstract: The transcriptional regulatory protein Fnr, acts as an intracellular redox sensor regulating a wide range of genes in response to changes in oxygen levels. Genome sequencing of Herbaspirillum seropedicae SmR1 revealed the presence of three fnr-like genes. In this study we have constructed single, double and triple fnr deletion mutant strains of H. seropedicae. Transcriptional profiling in combination with expression data from reporter fusions, together with spectroscopic analysis, demonstrates that the Fnr1 and Fnr3 proteins not only regulate expression of the cbb3-type respiratory oxidase, but also control the cytochrome content and other component complexes required for the cytochrome c-based electron transport pathway. Accordingly, in the absence of the three Fnr paralogs, growth is restricted at low oxygen tensions and nitrogenase activity is impaired. Our results suggest that the H. seropedicae Fnr proteins are major players in regulating the composition of the electron transport chain in response to prevailing oxygen concentrations.
authors.affiliation: Department of Biochemistry and Molecular Biology, Universidade Federal do Paraná, Curitiba-PR, Brazil.
authors.forename: Marcelo B
authors.initials: MB
authors.lastname: Batista
authors.forename: Michelle Z T
authors.initials: MZ
authors.lastname: Sfeir
authors.forename: Helisson
authors.initials: H
authors.lastname: Faoro
authors.forename: Roseli
authors.initials: R
authors.lastname: Wassem
authors.forename: Maria B R
authors.initials: MB
authors.lastname: Steffens
authors.forename: Fábio O
authors.initials: FO
authors.lastname: Pedrosa
authors.forename: Emanuel M
authors.initials: EM
authors.lastname: Souza
authors.forename: Ray
authors.initials: R
authors.lastname: Dixon
authors.forename: Rose A
authors.initials: RA
authors.lastname: Monteiro
mesh_terms: D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D003580:Cytochromes / Q000235:genetics / Q000378:metabolism*; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D045222:Electron Transport Chain Complex Proteins / Q000235:genetics / Q000378:metabolism*; D003576:Electron Transport Complex IV / Q000235:genetics / Q000378:metabolism*; D042803:Herbaspirillum / Q000502:physiology*; D016297:Mutagenesis, Site-Directed; D010100:Oxygen / Q000378:metabolism*
chemical_list: D001426:Bacterial Proteins; D003580:Cytochromes; D004268:DNA-Binding Proteins; D045222:Electron Transport Chain Complex Proteins; C414443:cbb3 oxidase; D003576:Electron Transport Complex IV; D010100:Oxygen