title: The extracytoplasmic function σ factor σ(C) regulates expression of a branched quinol oxidation pathway in Corynebacterium glutamicum.
abstract: Bacteria modify their expression of different terminal oxidases in response to oxygen availability. Corynebacterium glutamicum, a facultative anaerobic bacterium of the phylum Actinobacteria, possesses aa3 -type cytochrome c oxidase and cytochrome bd-type quinol oxidase, the latter of which is induced by oxygen limitation. We report that an extracytoplasmic function σ factor, σ(C) , is responsible for the regulation of this process. Chromatin immunoprecipitation with microarray analysis detected eight σ(C) -binding regions in the genome, facilitating the identification of a consensus promoter sequence for σ(C) recognition. The promoter sequences were found upstream of genes for cytochrome bd, heme a synthesis enzymes and uncharacterized membrane proteins, all of which were upregulated by sigC overexpression. However, one consensus promoter sequence found on the antisense strand upstream of an operon encoding the cytochrome bc1 complex conferred a σ(C) -dependent negative effect on expression of the operon. The σ(C) regulon was induced by cytochrome aa3 deficiency without modifying sigC expression, but not by bc1 complex deficiency. These findings suggest that σ(C) is activated in response to impaired electron transfer via cytochrome aa3 and not directly to a shift in oxygen levels. Our results reveal a new paradigm for transcriptional regulation of the aerobic respiratory system in bacteria.
authors.affiliation: Research institute of Innovative Technology for the Earth (RITE), 9-2 Kizugawadai, Kizugawa, Kyoto, 619-0292, Japan.
authors.forename: Koichi
authors.initials: K
authors.lastname: Toyoda
authors.affiliation: Research institute of Innovative Technology for the Earth (RITE), 9-2 Kizugawadai, Kizugawa, Kyoto, 619-0292, Japan.|Graduate School of Biological Sciences, Nara Institute of Science and Technology, 8916-5, Takayama, Ikoma, Nara, 630-0101, Japan.
authors.forename: Masayuki
authors.initials: M
authors.lastname: Inui
mesh_terms: D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D001665:Binding Sites / Q000235:genetics; D047369:Chromatin Immunoprecipitation; D048230:Corynebacterium glutamicum / Q000235:genetics / Q000378:metabolism*; D003573:Cytochrome b Group / Q000235:genetics; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D014450:Electron Transport Complex III / Q000235:genetics / Q000378:metabolism; D003576:Electron Transport Complex IV / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D017353:Gene Deletion; D015964:Gene Expression Regulation, Bacterial / Q000235:genetics*; D006873:Hydroquinones / Q000378:metabolism; D008565:Membrane Proteins / Q000235:genetics; D010084:Oxidation-Reduction; D010100:Oxygen / Q000378:metabolism; D011401:Promoter Regions, Genetic / Q000235:genetics; D011485:Protein Binding; D012808:Sigma Factor / Q000235:genetics / Q000378:metabolism*; D014158:Transcription, Genetic / Q000235:genetics*
chemical_list: D001426:Bacterial Proteins; C090098:CtaA protein, bacteria; D003573:Cytochrome b Group; D004268:DNA-Binding Proteins; D006873:Hydroquinones; D008565:Membrane Proteins; D012808:Sigma Factor; C081467:sigC protein, Bacteria; D003576:Electron Transport Complex IV; D014450:Electron Transport Complex III; D010100:Oxygen