Limits...
Assessment of CcpA-mediated catabolite control of gene expression in Bacillus cereus ATCC 14579.

van der Voort M, Kuipers OP, Buist G, de Vos WM, Abee T - BMC Microbiol. (2008)

Bottom Line: These results indicate CcpA to be involved in the regulation of glucose metabolism, thereby optimizing the efficiency of glucose catabolism.The catabolite control protein CcpA in B. cereus ATCC 14579 is involved in optimizing the catabolism of glucose with concomitant repression of gluconeogenesis and alternative metabolic pathways.Furthermore, the results point to metabolic control of enterotoxin gene expression and suggest that CcpA-mediated glucose sensing provides an additional mode of control in moderating the expression of the nhe and hbl operons in B. cereus ATCC 14579.

View Article: PubMed Central - HTML - PubMed

Affiliation: TI Food and Nutrition, Wageningen, The Netherlands. menno.vandervoort@wur.nl

ABSTRACT

Background: The catabolite control protein CcpA is a transcriptional regulator conserved in many Gram-positives, controlling the efficiency of glucose metabolism. Here we studied the role of Bacillus cereus ATCC 14579 CcpA in regulation of metabolic pathways and expression of enterotoxin genes by comparative transcriptome analysis of the wild-type and a ccpA-deletion strain.

Results: Comparative analysis revealed the growth performance and glucose consumption rates to be lower in the B. cereus ATCC 14579 ccpA deletion strain than in the wild-type. In exponentially grown cells, the expression of glycolytic genes, including a non-phosphorylating glyceraldehyde-3-phosphate dehydrogenase that mediates conversion of D-glyceraldehyde 3-phosphate to 3-phospho-D-glycerate in one single step, was down-regulated and expression of gluconeogenic genes and genes encoding the citric acid cycle was up-regulated in the B. cereus ccpA deletion strain. Furthermore, putative CRE-sites, that act as binding sites for CcpA, were identified to be present for these genes. These results indicate CcpA to be involved in the regulation of glucose metabolism, thereby optimizing the efficiency of glucose catabolism. Other genes of which the expression was affected by ccpA deletion and for which putative CRE-sites could be identified, included genes with an annotated function in the catabolism of ribose, histidine and possibly fucose/arabinose and aspartate. Notably, expression of the operons encoding non-hemolytic enterotoxin (Nhe) and hemolytic enterotoxin (Hbl) was affected by ccpA deletion, and putative CRE-sites were identified, which suggests catabolite repression of the enterotoxin operons to be CcpA-dependent.

Conclusion: The catabolite control protein CcpA in B. cereus ATCC 14579 is involved in optimizing the catabolism of glucose with concomitant repression of gluconeogenesis and alternative metabolic pathways. Furthermore, the results point to metabolic control of enterotoxin gene expression and suggest that CcpA-mediated glucose sensing provides an additional mode of control in moderating the expression of the nhe and hbl operons in B. cereus ATCC 14579.

Show MeSH

Related in: MedlinePlus

Differential gene expression during growth. The number of genes differently expressed in the ccpA deletion strain compared to the wild-type in four different growth phases (OD600 0.2 = early-exponential, OD600 0.8 = mid-exponential, OD600 4 = transition, OD600 8 = stationary). Both, the genes with a higher (grey bars) and a lower (black bars) expression in the ccpA deletion strain are shown. The light grey bars indicate the number of genes putatively regulated by a CRE-site, these are not shown for the transition and stationary phase.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC2358912&req=5

Figure 2: Differential gene expression during growth. The number of genes differently expressed in the ccpA deletion strain compared to the wild-type in four different growth phases (OD600 0.2 = early-exponential, OD600 0.8 = mid-exponential, OD600 4 = transition, OD600 8 = stationary). Both, the genes with a higher (grey bars) and a lower (black bars) expression in the ccpA deletion strain are shown. The light grey bars indicate the number of genes putatively regulated by a CRE-site, these are not shown for the transition and stationary phase.

Mentions: Analyses of the transcriptome data of the ccpA deletion strain compared to the wild-type in samples taken at the four time points indicated in figure 1, showed expression of a large number of ORFs to be affected upon ccpA deletion. Remarkably, the number of genes differentially expressed increased from 147 at early exponential phase to over 700 genes in the stationary phase (Fig. 2). The large differences in gene expression in transition and stationary phase cells of the ccpA deletion strain compared to that of the wild-type are conceivably affected by the respective presence and absence of glucose. Furthermore, these differences may point to the initiation of secondary effects of the ccpA deletion in these growth phases on gene expression and consequently cellular performance. Therefore, transcriptome analysis was focused on the early- and mid-exponential phase samples where glucose is still present at high levels in the cultures of both the ccpA deletion strain and the wild-type. In early-exponential phase, 103 genes showed higher expression and 44 genes showed a lower expression in the ccpA deletion strain compared to the wild-type. For mid-exponential phase cells these numbers were 127 and 54, respectively. When corrected for overlap between regulated genes in the early- and mid-exponential phase, a total of 173 genes expression in the exponential phase was shown to be higher in the ccpA deletion strain compared to the wild-type and for 80 genes expression in the ccpA deletion strain was observed to be lower than in the wild-type (Fig. 2). Consequently, genes that show a higher expression in the ccpA deletion strain are possibly repressed by CcpA, whereas genes that show a lower expression in the ccpA deletion strain may be activated by CcpA in the wild-type. The number of genes putatively regulated are similar to those described for CcpA-regulated genes in B. subtilis [17-19,21].


Assessment of CcpA-mediated catabolite control of gene expression in Bacillus cereus ATCC 14579.

van der Voort M, Kuipers OP, Buist G, de Vos WM, Abee T - BMC Microbiol. (2008)

Differential gene expression during growth. The number of genes differently expressed in the ccpA deletion strain compared to the wild-type in four different growth phases (OD600 0.2 = early-exponential, OD600 0.8 = mid-exponential, OD600 4 = transition, OD600 8 = stationary). Both, the genes with a higher (grey bars) and a lower (black bars) expression in the ccpA deletion strain are shown. The light grey bars indicate the number of genes putatively regulated by a CRE-site, these are not shown for the transition and stationary phase.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC2358912&req=5

Figure 2: Differential gene expression during growth. The number of genes differently expressed in the ccpA deletion strain compared to the wild-type in four different growth phases (OD600 0.2 = early-exponential, OD600 0.8 = mid-exponential, OD600 4 = transition, OD600 8 = stationary). Both, the genes with a higher (grey bars) and a lower (black bars) expression in the ccpA deletion strain are shown. The light grey bars indicate the number of genes putatively regulated by a CRE-site, these are not shown for the transition and stationary phase.
Mentions: Analyses of the transcriptome data of the ccpA deletion strain compared to the wild-type in samples taken at the four time points indicated in figure 1, showed expression of a large number of ORFs to be affected upon ccpA deletion. Remarkably, the number of genes differentially expressed increased from 147 at early exponential phase to over 700 genes in the stationary phase (Fig. 2). The large differences in gene expression in transition and stationary phase cells of the ccpA deletion strain compared to that of the wild-type are conceivably affected by the respective presence and absence of glucose. Furthermore, these differences may point to the initiation of secondary effects of the ccpA deletion in these growth phases on gene expression and consequently cellular performance. Therefore, transcriptome analysis was focused on the early- and mid-exponential phase samples where glucose is still present at high levels in the cultures of both the ccpA deletion strain and the wild-type. In early-exponential phase, 103 genes showed higher expression and 44 genes showed a lower expression in the ccpA deletion strain compared to the wild-type. For mid-exponential phase cells these numbers were 127 and 54, respectively. When corrected for overlap between regulated genes in the early- and mid-exponential phase, a total of 173 genes expression in the exponential phase was shown to be higher in the ccpA deletion strain compared to the wild-type and for 80 genes expression in the ccpA deletion strain was observed to be lower than in the wild-type (Fig. 2). Consequently, genes that show a higher expression in the ccpA deletion strain are possibly repressed by CcpA, whereas genes that show a lower expression in the ccpA deletion strain may be activated by CcpA in the wild-type. The number of genes putatively regulated are similar to those described for CcpA-regulated genes in B. subtilis [17-19,21].

Bottom Line: These results indicate CcpA to be involved in the regulation of glucose metabolism, thereby optimizing the efficiency of glucose catabolism.The catabolite control protein CcpA in B. cereus ATCC 14579 is involved in optimizing the catabolism of glucose with concomitant repression of gluconeogenesis and alternative metabolic pathways.Furthermore, the results point to metabolic control of enterotoxin gene expression and suggest that CcpA-mediated glucose sensing provides an additional mode of control in moderating the expression of the nhe and hbl operons in B. cereus ATCC 14579.

View Article: PubMed Central - HTML - PubMed

Affiliation: TI Food and Nutrition, Wageningen, The Netherlands. menno.vandervoort@wur.nl

ABSTRACT

Background: The catabolite control protein CcpA is a transcriptional regulator conserved in many Gram-positives, controlling the efficiency of glucose metabolism. Here we studied the role of Bacillus cereus ATCC 14579 CcpA in regulation of metabolic pathways and expression of enterotoxin genes by comparative transcriptome analysis of the wild-type and a ccpA-deletion strain.

Results: Comparative analysis revealed the growth performance and glucose consumption rates to be lower in the B. cereus ATCC 14579 ccpA deletion strain than in the wild-type. In exponentially grown cells, the expression of glycolytic genes, including a non-phosphorylating glyceraldehyde-3-phosphate dehydrogenase that mediates conversion of D-glyceraldehyde 3-phosphate to 3-phospho-D-glycerate in one single step, was down-regulated and expression of gluconeogenic genes and genes encoding the citric acid cycle was up-regulated in the B. cereus ccpA deletion strain. Furthermore, putative CRE-sites, that act as binding sites for CcpA, were identified to be present for these genes. These results indicate CcpA to be involved in the regulation of glucose metabolism, thereby optimizing the efficiency of glucose catabolism. Other genes of which the expression was affected by ccpA deletion and for which putative CRE-sites could be identified, included genes with an annotated function in the catabolism of ribose, histidine and possibly fucose/arabinose and aspartate. Notably, expression of the operons encoding non-hemolytic enterotoxin (Nhe) and hemolytic enterotoxin (Hbl) was affected by ccpA deletion, and putative CRE-sites were identified, which suggests catabolite repression of the enterotoxin operons to be CcpA-dependent.

Conclusion: The catabolite control protein CcpA in B. cereus ATCC 14579 is involved in optimizing the catabolism of glucose with concomitant repression of gluconeogenesis and alternative metabolic pathways. Furthermore, the results point to metabolic control of enterotoxin gene expression and suggest that CcpA-mediated glucose sensing provides an additional mode of control in moderating the expression of the nhe and hbl operons in B. cereus ATCC 14579.

Show MeSH
Related in: MedlinePlus