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Differential and cross-transcriptional control of duplicated genes encoding alternative sigma factors in Streptomyces ambofaciens.

ABSTRACT: The duplicated hasR and hasL genes of Streptomyces ambofaciens encode alternative sigma factors (named sigma(B(R)) and sigma(B(L))) belonging to the sigma(B) general stress response family in Bacillus subtilis. The duplication appears to be the result of a recent event that occurred specifically in S. ambofaciens. The two genes are 98% identical, and their deduced protein products exhibit 97% identity at the amino acid level. In contrast with the coding sequences, their genetic environments and their transcriptional control are strongly divergent. While hasL is monocistronic, hasR is arranged in a polycistronic unit with two upstream open reading frames, arsR and prsR, that encode putative anti-anti-sigma and anti-sigma factors, respectively. Transcription of each has gene is initiated from two promoters. In each case, one promoter was shown to be developmentally controlled and to be similar to those recognized by the B. subtilis general stress response sigma factor sigma(B). Expression from this type of promoter for each of the has genes dramatically increases during the course of growth in liquid or on solid media and following oxidative and osmotic stresses. Reverse transcription-PCR measurements indicate that hasR is 100 times more strongly expressed than hasL from the sigma(B)-like promoter. Transcription from the second promoter of each gene (located upstream of arsR in the case of the hasR locus) appears to be constitutive and weak. Quantitative transcriptional analysis in single and double has mutant strains revealed that sigma(B(R)) and sigma(B(L)) direct their own transcription as well as that of their duplicates. Only a slight sensitivity in response to oxidative conditions could be assigned to either single or double mutants, revealing the probable redundancy of the sigma factors implied in stress response in Streptomyces.

SUBMITTER: Roth V

PROVIDER: S-EPMC490935 | biostudies-literature | 2004 Aug

REPOSITORIES: biostudies-literature

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Differential and cross-transcriptional control of duplicated genes encoding alternative sigma factors in Streptomyces ambofaciens.

Roth Virginie V Aigle Bertrand B Bunet Robert R Wenner Thomas T Fourrier Céline C Decaris Bernard B Leblond Pierre P

Journal of bacteriology 20040801 16

The duplicated hasR and hasL genes of Streptomyces ambofaciens encode alternative sigma factors (named sigma(B(R)) and sigma(B(L))) belonging to the sigma(B) general stress response family in Bacillus subtilis. The duplication appears to be the result of a recent event that occurred specifically in S. ambofaciens. The two genes are 98% identical, and their deduced protein products exhibit 97% identity at the amino acid level. In contrast with the coding sequences, their genetic environments and ...[more]

PMID: 15292136

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Project description:BackgroundThe expression of genes in Corynebacterium glutamicum, a Gram-positive non-pathogenic bacterium used mainly for the industrial production of amino acids, is regulated by seven different sigma factors of RNA polymerase, including the stress-responsive ECF-sigma factor SigH. The sigH gene is located in a gene cluster together with the rshA gene, putatively encoding an anti-sigma factor. The aim of this study was to analyze the transcriptional regulation of the sigH and rshA gene cluster and the effects of RshA on the SigH regulon, in order to refine the model describing the role of SigH and RshA during stress response.ResultsTranscription analyses revealed that the sigH gene and rshA gene are cotranscribed from four sigH housekeeping promoters in C. glutamicum. In addition, a SigH-controlled rshA promoter was found to only drive the transcription of the rshA gene. To test the role of the putative anti-sigma factor gene rshA under normal growth conditions, a C. glutamicum rshA deletion strain was constructed and used for genome-wide transcription profiling with DNA microarrays. In total, 83 genes organized in 61 putative transcriptional units, including those previously detected using sigH mutant strains, exhibited increased transcript levels in the rshA deletion mutant compared to its parental strain. The genes encoding proteins related to disulphide stress response, heat stress proteins, components of the SOS-response to DNA damage and proteasome components were the most markedly upregulated gene groups. Altogether six SigH-dependent promoters upstream of the identified genes were determined by primer extension and a refined consensus promoter consisting of 45 original promoter sequences was constructed.ConclusionsThe rshA gene codes for an anti-sigma factor controlling the function of the stress-responsive sigma factor SigH in C. glutamicum. Transcription of rshA from a SigH-dependent promoter may serve to quickly shutdown the SigH-dependent stress response after the cells have overcome the stress condition. Here we propose a model of the regulation of oxidative and heat stress response including redox homeostasis by SigH, RshA and the thioredoxin system.

Dataset Information

Differential and cross-transcriptional control of duplicated genes encoding alternative sigma factors in Streptomyces ambofaciens.

Publications

Differential and cross-transcriptional control of duplicated genes encoding alternative sigma factors in Streptomyces ambofaciens.

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