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CRP interacts with promoter‐bound σ 54 RNA polymerase and blocks transcriptional activation of the dctA promoter
Author(s) -
Wang YiPing,
Kolb Annie,
Buck Martin,
Wen Jin,
O'Gara Fergal,
Buc Henri
Publication year - 1998
Publication title -
the embo journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 7.484
H-Index - 392
eISSN - 1460-2075
pISSN - 0261-4189
DOI - 10.1093/emboj/17.3.786
Subject(s) - biology , sigma factor , rna polymerase , microbiology and biotechnology , promoter , polymerase , rna polymerase ii , rna , genetics , gene , gene expression
The cAMP receptor protein (CRP) is an activator of σ 70 ‐dependent transcription. Analysis of the σ 54 ‐dependent dctA promoter reveals a novel negative regulatory function for CRP. CRP can bind to two distant sites of the dctA promoter, sites which overlap the upstream activator sequences for the DctD activator. CRP interacts with Eσ 54 bound at the dctA promoter via DNA loop formation. When the CRP‐binding sites are deleted, CRP still interacts in a cAMP‐dependent manner with the stable Eσ 54 closed complex via protein–protein contacts. CRP is able to repress activation of the dctA promoter, even in the absence of specific CRP‐binding sites. CRP affects both the final level and the kinetics of activation. The establishment of the repression and its release by the NtrC activator proceed via slow processes. The kinetics suggest that CRP favours a new form of closed complex which interconverts slowly with the classical closed intermediate. Only the latter is capable of interacting with an activator to form an open promoter complex. Thus, Eσ 54 promoters are responsive to CRP, a protein unrelated to σ 54 activators, and the repression exerted is the direct result of an interaction between Eσ 54 and the CRP–cAMP complex.