PMID:17496092

Citation	Kaufman, GE and Yother, J (2007) CcpA-dependent and -independent control of beta-galactosidase expression in Streptococcus pneumoniae occurs via regulation of an upstream phosphotransferase system-encoding operon. J. Bacteriol. 189:5183-92
Abstract	A spontaneous mutant of Streptococcus pneumoniae strain D39 exhibiting elevated beta-galactosidase activity was identified. We determined that the beta-galactosidase activity was due to BgaA, a surface protein in S. pneumoniae, and that the expression of bgaA was regulated. Transcription analyses demonstrated expression of bgaA in the constitutive beta-galactosidase (BgaA(C)) mutant, but not in the parent. beta-Galactosidase expression was induced in the parent under specific growth conditions; however, the levels did not reach those of the BgaA(C) mutant. We localized the mutation resulting in the BgaA(C) phenotype to a region upstream of bgaA and in the promoter of a phosphoenolpyruvate-dependent phosphotransferase system (PTS) operon. The mutation was in a catabolite-responsive element (cre) and affected the binding of CcpA (catabolite control protein A), a key regulator of many carbon metabolism genes. The pts operon and bgaA were cotranscribed, and their transcription was regulated by CcpA. Deletion of ccpA altered beta-galactosidase activity, leading to a sevenfold increase in the parent but a fivefold decrease in the BgaA(C) mutant. The resulting beta-galactosidase activities were the same in the two strains, suggesting the presence of a second repressor. The presence of glucose in the growth medium resulted in pts-bgaA repression by both CcpA and the second repressor, with the latter being important in responding to the glucose concentration. Expression of beta-galactosidase is important for S. pneumoniae adherence during colonization of the nasopharynx, a site normally devoid of glucose. CcpA and environmental glucose concentrations thus appear to play important roles in the regulation of a niche-specific virulence factor.
Links	PubMed PMC1951873 Online version:10.1128/JB.00449-07
Keywords	Bacterial Proteins/genetics; Bacterial Proteins/metabolism; Bacterial Proteins/physiology; Base Sequence; DNA-Binding Proteins/genetics; DNA-Binding Proteins/metabolism; DNA-Binding Proteins/physiology; Electrophoretic Mobility Shift Assay; Gene Deletion; Gene Expression Regulation, Bacterial/drug effects; Glucose/pharmacology; Molecular Sequence Data; Mutation; Operon; Phosphoenolpyruvate Sugar Phosphotransferase System/genetics; Phosphoenolpyruvate Sugar Phosphotransferase System/metabolism; Promoter Regions, Genetic; Protein Binding; Repressor Proteins/genetics; Repressor Proteins/metabolism; Repressor Proteins/physiology; Streptococcus pneumoniae/genetics; Streptococcus pneumoniae/growth & development; Streptococcus pneumoniae/metabolism; Transcription, Genetic; beta-Galactosidase/genetics; beta-Galactosidase/metabolism
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Annotations

Gene product	Qualifier	GO Term	Evidence Code	with/from	Aspect	Extension	Notes	Status
STRP2:A0A0H2ZQ65		GO:0010944: negative regulation of transcription by competitive promoter binding	ECO:0000315:		P		Figure 4A: Which describes the negative regulation of B-galactosidase via the ccpa protein in Streptococcus pneumoniae strain D39 serotype 2. In the control, the deletion of catabolite control protein A (ccpa) resulted in an increase in the transcript levels of bga and pts. In the the BgaAC mutant, a decrease in transcription occurred for both bga and pts. Figure 5: Showing that the D39 pts promoter expressed a higher affinity for the CcpA protein rather than the second repressor. The BgaAC mutant bacteria with its pts promoter expressed the higher affinity for the second repressor.	complete CACAO 12321

References

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