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Direct and indirect roles of CcpA in regulation of Bacillus subtilis Krebs cycle genes
Author(s) -
Kim HyunJin,
Roux Agnes,
Sonenshein Abraham L.
Publication year - 2002
Publication title -
molecular microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.857
H-Index - 247
eISSN - 1365-2958
pISSN - 0950-382X
DOI - 10.1046/j.1365-2958.2002.03003.x
Subject(s) - ccpa , catabolite repression , derepression , biology , bacillus subtilis , inducer , mutant , aconitase , fed batch culture , repressor , psychological repression , biochemistry , transcription (linguistics) , gene , transcription factor , genetics , microbiology and biotechnology , enzyme , gene expression , bacteria , linguistics , philosophy , fermentation
Summary Carbon catabolite repression of the Bacillus subtilis citrate synthase ( citZ ) and aconitase ( citB ) genes, previously known to be regulated by CcpC, was shown to depend on CcpA as well. Transcription of the citZ gene was partially derepressed in ccpA and ccpC single mutants and fully derepressed in a ccpA ccpC double mutant. DNase I footprinting studies showed that CcpA binds to a catabolite‐responsive element ( cre ) site located at positions + 80 to + 97 with respect to the transcription start site, whereas CcpC binds at positions − 14 to + 6 and + 16 to + 36. Mutations in the citZ cre site greatly altered CcpA binding and repression. A ccpA null mutation also caused partial derepression of citB . Disruption of citrate synthase activity, however, suppressed the effect of the ccpA mutation, suggesting that increased citrate accumulation in a ccpA mutant partially inactivates CcpC and causes partial derepression of citB . Therefore, CcpA controls expression of Krebs cycle genes directly by regulating transcription of citZ and in‐directly by regulating availability of citrate, the inducer for CcpC.