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Effect of a glucose impulse on the CcpA regulon in Staphylococcus aureus.

Seidl K, Müller S, François P, Kriebitzsch C, Schrenzel J, Engelmann S, Bischoff M, Berger-Bächi B - BMC Microbiol. (2009)

Bottom Line: Phosphotransacetylase and acetate kinase, converting acetyl-CoA to acetate with a concomitant substrate-level phosphorylation, were neither regulated by glucose nor by CcpA.Interestingly, the expression of a larger number of genes was found to be affected by ccpA inactivation in the absence of glucose than after glucose addition, suggesting that glucose-independent effects due to CcpA may have a particular impact in S. aureus.In the presence of glucose, CcpA was found to regulate the expression of genes involved in metabolism, but also that of genes coding for virulence determinants.

View Article: PubMed Central - HTML - PubMed

Affiliation: Institute of Medical Microbiology, University of Zürich, Zürich, Switzerland. katiseidl@gmail.com

ABSTRACT

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 Staphylococcus aureus, focussing on short-time effects of glucose under stable pH conditions.

Results: The addition of glucose to exponentially growing S. aureus increased the expression of genes and enzymes of the glycolytic pathway, while genes and proteins of the tricarboxylic acid (TCA) cycle, required for the complete oxidation of glucose, were repressed via CcpA. Phosphotransacetylase and acetate kinase, converting acetyl-CoA to acetate with a concomitant substrate-level phosphorylation, were neither regulated by glucose nor by CcpA. CcpA directly repressed genes involved in utilization of amino acids as secondary carbon sources. Interestingly, the expression of a larger number of genes was found to be affected by ccpA inactivation in the absence of glucose than after glucose addition, suggesting that glucose-independent effects due to CcpA may have a particular impact in S. aureus. In the presence of glucose, CcpA was found to regulate the expression of genes involved in metabolism, but also that of genes coding for virulence determinants.

Conclusion: This study describes the CcpA regulon of exponentially growing S. aureus cells. As in other bacteria, CcpA of S. aureus seems to control a large regulon that comprises metabolic genes as well as virulence determinants that are affected in their expression by CcpA in a glucose-dependent as well as -independent manner.

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Functional classes of CcpA-dependent genes. Functional classification according to the DOGAN website [26] of genes that were found to be regulated by CcpA in a glucose-independent (A) or a glucose-dependent way (B). Categories indicated are: A, Similar to unknown proteins/no similarity; B, Metabolism of carbohydrates and related molecules; C, Transport/binding proteins and lipoproteins; D, Metabolism of amino acids and related molecules; E, Adaption to atypical conditions; F, Pathogenic factors; G, Protein synthesis; H, Metabolism of nucleotides and nucleic acids; I, Metabolism of coenzymes and prosthetic groups; J, Membrane bioenergetics; K, RNA synthesis; L, Metabolism of lipids; M, Miscellaneous; N, Cell wall; O, Detoxification; P, Sensors; Q, Cell division; R, DNA replication; S, Protein folding; T, DNA recombination; U, DNA recombination.
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Figure 3: Functional classes of CcpA-dependent genes. Functional classification according to the DOGAN website [26] of genes that were found to be regulated by CcpA in a glucose-independent (A) or a glucose-dependent way (B). Categories indicated are: A, Similar to unknown proteins/no similarity; B, Metabolism of carbohydrates and related molecules; C, Transport/binding proteins and lipoproteins; D, Metabolism of amino acids and related molecules; E, Adaption to atypical conditions; F, Pathogenic factors; G, Protein synthesis; H, Metabolism of nucleotides and nucleic acids; I, Metabolism of coenzymes and prosthetic groups; J, Membrane bioenergetics; K, RNA synthesis; L, Metabolism of lipids; M, Miscellaneous; N, Cell wall; O, Detoxification; P, Sensors; Q, Cell division; R, DNA replication; S, Protein folding; T, DNA recombination; U, DNA recombination.

Mentions: Genes showing an altered expression in the ΔccpA mutant compared to the wild-type when growing in LB alone, without glucose addition, are listed in Additional files 1: Genes with lower expression in wild-type versus ΔccpA mutant, and 2: Genes with higher expression in wild-type versus ΔccpA mutant. These genes made up the largest regulatory group found in our study (226 genes). Only a minor part of this group of genes (38 out of 226) contained putative cre-sites in their promoter regions or were part of operons with putative cre-sites, suggesting that CcpA may affect the expression of the majority of these genes indirectly. Such indirect effects may reflect differences in the generation of metabolites due to ccpA inactivation, which might serve as cofactors for the regulation of further genes, and/or to a CcpA-dependent control of regulatory proteins or RNAs. Our findings suggest that glucose-independent effects due to CcpA might play a particularly important role in S. aureus. For a better understanding, the genes of this category were grouped into functional classes (Fig. 3A). While unknown proteins represented the largest group (61 genes), this group was followed by proteins of carbon metabolism (26 genes), transport/binding proteins and lipoproteins (25 genes), and proteins of amino acid metabolism (19 genes).


Effect of a glucose impulse on the CcpA regulon in Staphylococcus aureus.

Seidl K, Müller S, François P, Kriebitzsch C, Schrenzel J, Engelmann S, Bischoff M, Berger-Bächi B - BMC Microbiol. (2009)

Functional classes of CcpA-dependent genes. Functional classification according to the DOGAN website [26] of genes that were found to be regulated by CcpA in a glucose-independent (A) or a glucose-dependent way (B). Categories indicated are: A, Similar to unknown proteins/no similarity; B, Metabolism of carbohydrates and related molecules; C, Transport/binding proteins and lipoproteins; D, Metabolism of amino acids and related molecules; E, Adaption to atypical conditions; F, Pathogenic factors; G, Protein synthesis; H, Metabolism of nucleotides and nucleic acids; I, Metabolism of coenzymes and prosthetic groups; J, Membrane bioenergetics; K, RNA synthesis; L, Metabolism of lipids; M, Miscellaneous; N, Cell wall; O, Detoxification; P, Sensors; Q, Cell division; R, DNA replication; S, Protein folding; T, DNA recombination; U, DNA recombination.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC2697999&req=5

Figure 3: Functional classes of CcpA-dependent genes. Functional classification according to the DOGAN website [26] of genes that were found to be regulated by CcpA in a glucose-independent (A) or a glucose-dependent way (B). Categories indicated are: A, Similar to unknown proteins/no similarity; B, Metabolism of carbohydrates and related molecules; C, Transport/binding proteins and lipoproteins; D, Metabolism of amino acids and related molecules; E, Adaption to atypical conditions; F, Pathogenic factors; G, Protein synthesis; H, Metabolism of nucleotides and nucleic acids; I, Metabolism of coenzymes and prosthetic groups; J, Membrane bioenergetics; K, RNA synthesis; L, Metabolism of lipids; M, Miscellaneous; N, Cell wall; O, Detoxification; P, Sensors; Q, Cell division; R, DNA replication; S, Protein folding; T, DNA recombination; U, DNA recombination.
Mentions: Genes showing an altered expression in the ΔccpA mutant compared to the wild-type when growing in LB alone, without glucose addition, are listed in Additional files 1: Genes with lower expression in wild-type versus ΔccpA mutant, and 2: Genes with higher expression in wild-type versus ΔccpA mutant. These genes made up the largest regulatory group found in our study (226 genes). Only a minor part of this group of genes (38 out of 226) contained putative cre-sites in their promoter regions or were part of operons with putative cre-sites, suggesting that CcpA may affect the expression of the majority of these genes indirectly. Such indirect effects may reflect differences in the generation of metabolites due to ccpA inactivation, which might serve as cofactors for the regulation of further genes, and/or to a CcpA-dependent control of regulatory proteins or RNAs. Our findings suggest that glucose-independent effects due to CcpA might play a particularly important role in S. aureus. For a better understanding, the genes of this category were grouped into functional classes (Fig. 3A). While unknown proteins represented the largest group (61 genes), this group was followed by proteins of carbon metabolism (26 genes), transport/binding proteins and lipoproteins (25 genes), and proteins of amino acid metabolism (19 genes).

Bottom Line: Phosphotransacetylase and acetate kinase, converting acetyl-CoA to acetate with a concomitant substrate-level phosphorylation, were neither regulated by glucose nor by CcpA.Interestingly, the expression of a larger number of genes was found to be affected by ccpA inactivation in the absence of glucose than after glucose addition, suggesting that glucose-independent effects due to CcpA may have a particular impact in S. aureus.In the presence of glucose, CcpA was found to regulate the expression of genes involved in metabolism, but also that of genes coding for virulence determinants.

View Article: PubMed Central - HTML - PubMed

Affiliation: Institute of Medical Microbiology, University of Zürich, Zürich, Switzerland. katiseidl@gmail.com

ABSTRACT

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 Staphylococcus aureus, focussing on short-time effects of glucose under stable pH conditions.

Results: The addition of glucose to exponentially growing S. aureus increased the expression of genes and enzymes of the glycolytic pathway, while genes and proteins of the tricarboxylic acid (TCA) cycle, required for the complete oxidation of glucose, were repressed via CcpA. Phosphotransacetylase and acetate kinase, converting acetyl-CoA to acetate with a concomitant substrate-level phosphorylation, were neither regulated by glucose nor by CcpA. CcpA directly repressed genes involved in utilization of amino acids as secondary carbon sources. Interestingly, the expression of a larger number of genes was found to be affected by ccpA inactivation in the absence of glucose than after glucose addition, suggesting that glucose-independent effects due to CcpA may have a particular impact in S. aureus. In the presence of glucose, CcpA was found to regulate the expression of genes involved in metabolism, but also that of genes coding for virulence determinants.

Conclusion: This study describes the CcpA regulon of exponentially growing S. aureus cells. As in other bacteria, CcpA of S. aureus seems to control a large regulon that comprises metabolic genes as well as virulence determinants that are affected in their expression by CcpA in a glucose-dependent as well as -independent manner.

Show MeSH
Related in: MedlinePlus