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The extracytoplasmic function σ factor σ C regulates expression of a branched quinol oxidation pathway in Corynebacterium glutamicum
Author(s) -
Toyoda Koichi,
Inui Masayuki
Publication year - 2016
Publication title -
molecular microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.857
H-Index - 247
eISSN - 1365-2958
pISSN - 0950-382X
DOI - 10.1111/mmi.13330
Subject(s) - biology , corynebacterium glutamicum , operon , regulon , heme a , cytochrome c oxidase , cytochrome , chromatin immunoprecipitation , cytochrome c , biochemistry , promoter , gene , microbiology and biotechnology , regulation of gene expression , gene expression , mitochondrion , mutant , enzyme
Summary Bacteria modify their expression of different terminal oxidases in response to oxygen availability. Corynebacterium glutamicum , a facultative anaerobic bacterium of the phylum Actinobacteria, possesses aa 3 ‐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 bc 1 complex conferred a σ C ‐dependent negative effect on expression of the operon. The σ C regulon was induced by cytochrome aa 3 deficiency without modifying sigC expression, but not by bc 1 complex deficiency. These findings suggest that σ C is activated in response to impaired electron transfer via cytochrome aa 3 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.