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Microarray-based analysis of the Staphylococcus aureus sigmaB regulon.

ABSTRACT: Microarray-based analysis of the transcriptional profiles of the genetically distinct Staphylococcus aureus strains COL, GP268, and Newman indicate that a total of 251 open reading frames (ORFs) are influenced by sigmaB activity. While sigmaB was found to positively control 198 genes by a factor of > or =2 in at least two of the three genetic lineages analyzed, 53 ORFs were repressed in the presence of sigmaB. Gene products that were found to be influenced by sigmaB are putatively involved in all manner of cellular processes, including cell envelope biosynthesis and turnover, intermediary metabolism, and signaling pathways. Most of the genes and/or operons identified as upregulated by sigmaB were preceded by a nucleotide sequence that resembled the sigmaB consensus promoter sequence of Bacillus subtilis. A conspicuous number of virulence-associated genes were identified as regulated by sigmaB activity, with many adhesins upregulated and prominently represented in this group, while transcription of various exoproteins and toxins were repressed. The data presented here suggest that the sigmaB of S. aureus controls a large regulon and is an important modulator of virulence gene expression that is likely to act conversely to RNAIII, the effector molecule of the agr locus. We propose that this alternative transcription factor may be of importance for the invading pathogen to fine-tune its virulence factor production in response to changing host environments.

SUBMITTER: Bischoff M

PROVIDER: S-EPMC421609 | biostudies-literature | 2004 Jul

REPOSITORIES: biostudies-literature

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Microarray-based analysis of the Staphylococcus aureus sigmaB regulon.

Bischoff Markus M Dunman Paul P Kormanec Jan J Macapagal Daphne D Murphy Ellen E Mounts William W Berger-Bächi Brigitte B Projan Steven S

Journal of bacteriology 20040701 13

Microarray-based analysis of the transcriptional profiles of the genetically distinct Staphylococcus aureus strains COL, GP268, and Newman indicate that a total of 251 open reading frames (ORFs) are influenced by sigmaB activity. While sigmaB was found to positively control 198 genes by a factor of > or =2 in at least two of the three genetic lineages analyzed, 53 ORFs were repressed in the presence of sigmaB. Gene products that were found to be influenced by sigmaB are putatively involved in al ...[more]

PMID: 15205410

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Project description:Background The catabolite control protein A (CcpA) is a member of the LacI/GalR family of transcriptional regulators controlling carbon-metabolism pathways in low-GC Gram positive bacteria. It functions as a catabolite repressor or activator, allowing the bacteria to utilize the preferred carbon source over secondary carbon sources. This study is the first CcpA-dependent transcriptome and proteome analysis in S. aureus wild type and ccpA-deleted mutant, focussing on short-time effects of glucose under stable pH conditions. Results The addition of glucose to exponentially growing S. aureus increased enzymes of glycolytic pathway, indicating a higher glycolytic activity, while proteins required for the complete oxidation in the TCA cycle were repressed via CcpA. Phosphotransacetylase and acetate kinase, converting acetylCoA to acetate with a concomitant substrate-level phosphorylation were neither regulated by glucose nor by CcpA. Most CcpA directly repressed genes were involved in utilization of amino acids as secondary carbon sources. More genes were found to be differentially expressed by CcpA in a glucose-independent manner than in the classical, glucose dependent way, suggesting that glucose-independent regulation by CcpA may be of particular importance in S. aureus. In the presence of glucose, CcpA was found to regulate expression of genes involved in metabolism, but that of genes coding for virulence determinants. Conclusions This study identified the CcpA regulon of exponentially growing S. aureus, for the first time. As in other bacteria, the CcpA-regulon of S. aureus comprised a large amount of metabolic genes but also some 50 genes associated with virulence. CcpA seemed to work in a glucose- as well as glucose-independent way. The transcriptomes of strain Newman and its isogenic ccpA-deleted mutant were determined in early exponential growth and 30 min after the addition of 10 mM glucose, under controlled pH conditions. In the absence of glucose, the wild type grew slightly faster than the mutant, reaching an OD600 of 1 approximately 20 min earlier than the mutant. Adding 10 mM glucose at OD600 1 increased the growth rate of the wild type but had only a minor effect on that of the mutant. 60 min after glucose addition, glucose was depleted down to 0.3 mM by the wild type, while still 3 mM glucose was left in the culture of the mutant. Despite increased glucose consumption rates in the wild type, acetate production was only slightly enhanced compared to the mutant. No lactate was excreted at any time point sampled. Acidification of the medium upon glucose metabolism was prevented by buffering, maintaining a pH of 7.5 for both strains and under both growth conditions for at least 2 h after glucose addition, allowing to rule out any pH effects.

Dataset Information

Microarray-based analysis of the Staphylococcus aureus sigmaB regulon.

Publications

Microarray-based analysis of the Staphylococcus aureus sigmaB regulon.

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