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Evidence that Bacillus catabolite control protein CcpA interacts with RNA polymerase to inhibit transcription
Author(s) -
Kim JeongHo,
Yang YoungKi,
Chambliss Glenn H.
Publication year - 2005
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 - 10.1111/j.1365-2958.2005.04496.x
Subject(s) - ccpa , catabolite repression , biology , rna polymerase , transcription (linguistics) , operon , repressor , promoter , lac operon , transcription factor , microbiology and biotechnology , gene , rna , biochemistry , gene expression , escherichia coli , linguistics , philosophy , mutant
Summary Bacillusc atabolite c ontrol p rotein (CcpA) mediates carbon catabolite repression (CCR) by controlling expression of catabolite responsive (CR) genes or operons through interaction with c atabolite r esponsive e lements ( cre s) located within or outside of CR promoters. Here, we investigated how CcpA inhibits the transcription of CR promoters in vitro . CcpA has different affinities for different cre s, but this does not correlate with its ability to inhibit transcription. In the amyE promoter, which overlaps a CcpA binding site ( amyE cre centred at +4.5), CcpA does not prevent RNA polymerase (RNAP) binding to the promoter; it may even interact with RNAP. Inserting non‐integral turns of helix (1.5 and 2.5) between the amyE promoter (−10 hexamer) and the amyE cre relieved CCR of amyE expression. In the xyl operon, despite the downstream location of its cre (a major cre centred at +130.5), CcpA blocked transcription initiation, not elongation (roadblock) at the site of the cre . Taken together, our results strongly suggest that CcpA requires interactions with RNAP to inhibit transcription.