Escherichia coli contains more than 250 known promoters that must be activated prior to transcription. cAMP receptor protein (crp), also known as cAMP regulatory protein and catabolite gene activator, is a 210 amino acid E. coli protein that complexes with cyclic AMP and binds to specific DNA sites near the promoter, resulting in homodimeric transcription activation of more than 100 E. coli promoters. Acting as a negative regulator against its own synthesis, crp regulates transcription of several catabolite-sensitive operons. Crp activates transcription by making multiple interactions with RNA polymerase. Containing one cyclic nucleotide binding domain and one HTH crp-type DNA binding domain, crp binds DNA as a dimer to induce a severe bend in the DNA. This formation is a regulatory mechanism of crp gene expression that plays a major role in determining the molecular mechanism in gene transcription.
Function:
A global transcription regulator. Complexes with cyclic AMP (cAMP) which allosterically activates DNA binding (to consensus sequence 5'-AAATGTGATCTAGATCACATTT-3') to directly regulate the transcription of about 300 genes in about 200 operons and indirectly regulate the expression of about half the genome. There are 3 classes of CRP promoters; class I promoters have a single CRP-binding site upstream of the RNA polymerase (RNAP)-binding site, whereas in class II promoters the single CRP- and RNAP-binding site overlap, CRP making multiple contacts with RNAP. Class III promoters require multiple activator molecules, including at least one CRP dimer. It can act as an activator, repressor, coactivator or corepressor. Induces a severe bend in DNA (about 87 degrees), bringing upstream promoter elements into contact with RNAP. Acts as a negative regulator of its own synthesis as well as for adenylate cyclase (cyaA), which generates cAMP. High levels of active CRP are detrimental to growth (PubMed:16260780). Plays a major role in carbon catabolite repression (CCR). CCR involves cAMP, adenylate cyclase (cyaA), CRP and the EIIA-Glc component of the PTS (crr). In the presence of glucose EIIA-Glc is dephosphorylated, and does not activate adenylate cyclase, leading to reduced cAMP and thus decreased CRP activity. Also plays a role in many other processes (see PubMed:22573269).
Subunit:
Homodimer, which upon binding cAMP is able to bind DNA. AR1 of the upstream subunit binds to the SLCterminus of RNAP subunit RpoA, AR2 of the downstream subunit binds to the N-terminus of RpoA while AR3 binds to sigma-70 (RpoD).
SWISS:
P0ACJ8
Gene ID:
5892182
Database links:
UniProtKB/Swiss-Prot: P0ACJ8.1
Contains 1 cyclic nucleotide-binding domain.
Contains 1 HTH crp-type DNA-binding domain.
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