Unknown,Transcriptomics,Genomics,Proteomics

Dataset Information

Overexpression of sigC in the wild type

ABSTRACT: Bacteria modify expression of different types of terminal oxidase in response to oxygen availability. Corynebacterium glutamicum, a facultative anaerobic bacterium in Actinobacteria, possesses aa3-type cytochrome c oxidase and cytochrome bd-type quinol oxidase, the latter of which is induced upon oxygen limitation. We report here that an extracytoplasmic function sigma factor, SigC, is unprecedentedly responsible for the regulation. Chromatin immunoprecipitation in conjunction with microarray (ChIP-chip) analysis detected eight SigC-binding regions in the genome, leading to identification of a consensus promoter sequence for SigC 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. In contrast, that found on the antisense strand upstream of an operon encoding the cytochrome bc1 complex conferred a SigC-dependent negative effect on the operon expression. The SigC regulon was induced by cytochrome aa3 deficiency without modification of expression of sigC itself, but not by deficiency of the bc1 complex. These findings suggest that SigC is activated in response to impairment of electron transfer via cytochrome aa3, not directly to shift in oxygen levels. Our results provide a novel paradigm for transcriptional regulation of the aerobic respiratory system in bacteria. Comparison of gene expression profiles of the wild type before and after sigC overexpression at the exponential phase. Three independent experiments were performed.

ORGANISM(S): Corynebacterium glutamicum

SUBMITTER: Masayuki Inui

PROVIDER: E-GEOD-72451 | biostudies-arrayexpress |

REPOSITORIES: biostudies-arrayexpress

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Publications

The extracytoplasmic function σ factor σ(C) regulates expression of a branched quinol oxidation pathway in Corynebacterium glutamicum.

Toyoda Koichi K Inui Masayuki M

Molecular microbiology 20160222 3

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 ...[more]

PMID: 26789738

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Project description:The response regulator HrrA belonging to the HrrSA two-component system (previously named CgtSR11) is known to be repressed by the global iron-dependent regulator DtxR in Corynebacterium glutamicum. Sequence analysis indicated an involvement of the HrrSA system in heme-dependent gene expression. Growth experiments revealed that the non-pathogenic soil bacterium C. glutamicum is able to use hemin or hemoglobin as sole iron source. In DNA microarray analyses a putative operon encoding the hemin-binding protein HtaA and the putative hemin ABC transporter HmuTUV showed a strong upregulation in heme-grown cells. Deletion of the hmu operon clearly affects heme utilization, but does not completely abolish growth on heme or hemoglobin. As a central part of this study, we investigated the regulon of the response regulator HrrA via comparative transcriptome analysis of a hrrA deletion mutant and C. glutamicum wild type in combination with DNA-protein interaction studies with purified HrrA protein. Our data provide evidence for a heme-dependent transcriptional activation of heme oxygenase (hmuO), an enzyme involved in the utilization of heme as iron source. Besides hmuO, HrrA was shown to activate the expression of heme-containing components of the respiratory chain, namely ctaD and the ctaE-qcrCAB operon encoding subunits I and III of cytochrome aa3 oxidase and three subunits of the cytochrome bc1 complex. Furthermore, HrrA represses almost all genes involved in heme biosynthesis, including glutamyl-tRNA reductase (hemA), uroporphyrinogen decarboxylase (hemE), and ferrochelatase (hemH). Thus, our data clearly emphasize a central role of the HrrSA system in the control of heme homeostasis in C. glutamicum. Three biological replicates of each experiment were performed. Experiment 1: Transcriptome comparison of wild type grown und FeSO4 or heme as iron source; Exp. 2: WT vs. hrrA deletion mutant grown on FeSO4; Exp. 3: WT vs. hrrA mutant grown on heme. For analysis via DNA microarraysose RNA was isolated from exponentially growing cells cultivated in CgXII medium containing glucose as carbon source and either 2.5 uM FeSO4 or 2.5 uM heme as iron source.

Dataset Information

Overexpression of sigC in the wild type

Publications

The extracytoplasmic function σ factor σ(C) regulates expression of a branched quinol oxidation pathway in Corynebacterium glutamicum.

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