1zrc
4 Crystal structures of CAP-DNA with all base-pair substitutions at position 6, CAP-ICAP38 DNA
Structural highlights
FunctionCRP_ECOLI This protein complexes with cyclic AMP and binds to specific DNA sites near the promoter to regulate the transcription of several catabolite-sensitive operons. The protein induces a severe bend in the DNA. Acts as a negative regulator of its own synthesis as well as for adenylate cyclase (cyaA), which generates cAMP.[1] Evolutionary Conservation Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf. Publication Abstract from PubMedThe catabolite activator protein (CAP) bends DNA in the CAP-DNA complex, typically introducing a sharp DNA kink, with a roll angle of approximately 40 degrees and a twist angle of approximately 20 degrees, between positions 6 and 7 of the DNA half-site, 5'-A1A2A3T4G5T6G7A8T9C10T11 -3' ("primary kink"). In previous work, we showed that CAP recognizes the nucleotide immediately 5' to the primary-kink site, T6, through an "indirect-readout" mechanism involving sequence effects on energetics of primary-kink formation. Here, to understand further this example of indirect readout, we have determined crystal structures of CAP-DNA complexes containing each possible nucleotide at position 6. The structures show that CAP can introduce a DNA kink at the primary-kink site with any nucleotide at position 6. The DNA kink is sharp with the consensus pyrimidine-purine step T6G7 and the non-consensus pyrimidine-purine step C6G7 (roll angles of approximately 42 degrees, twist angles of approximately 16 degrees ), but is much less sharp with the non-consensus purine-purine steps A6G7 and G6G7 (roll angles of approximately 20 degrees, twist angles of approximately 17 degrees). We infer that CAP discriminates between consensus and non-consensus pyrimidine-purine steps at positions 6-7 solely based on differences in the energetics of DNA deformation, but that CAP discriminates between the consensus pyrimidine-purine step and non-consensus purine-purine steps at positions 6-7 both based on differences in the energetics of DNA deformation and based on qualitative differences in DNA deformation. The structures further show that CAP can achieve a similar, approximately 46 degrees per DNA half-site, overall DNA bend through a sharp DNA kink, a less sharp DNA kink, or a smooth DNA bend. Analysis of these and other crystal structures of CAP-DNA complexes indicates that there is a large, approximately 28 degrees per DNA half-site, out-of-plane component of CAP-induced DNA bending in structures not constrained by end-to-end DNA lattice interactions and that lattice contacts involving CAP tend to involve residues in or near biologically functional surfaces. Indirect readout of DNA sequence at the primary-kink site in the CAP-DNA complex: recognition of pyrimidine-purine and purine-purine steps.,Napoli AA, Lawson CL, Ebright RH, Berman HM J Mol Biol. 2006 Mar 17;357(1):173-83. Epub 2006 Jan 3. PMID:16427082[2] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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