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PROTEIN-DNA RECOGNITION AND DNA DEFORMATION REVEALED IN CRYSTAL STRUCTURES OF CAP-DNA COMPLEXES
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) makes no direct contact with the consensus base-pair T:A at position 6 of the DNA half-site 5'-A(1)A(2)A(3)T(4)G(5)T(6)G(7)A(8)T(9)C(10)T(11)-3' but, nevertheless, exhibits strong specificity for T:A at position 6. Binding of CAP results in formation of 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. The consensus base-pair T:A at position 6 and the consensus base-pair G:C at position 7 form a T:A/G:C step, which is known to be associated with DNA flexibility. It has been proposed that specificity for T:A at position 6 is a consequence of formation of the DNA kink between positions 6 and 7, and of effects of the T:A(6)/G:C(7) step on the geometry of DNA kinking, or the energetics of DNA kinking. In this work, we determine crystallographic structures of CAP-DNA complexes having the consensus base-pair T:A at position 6 or the non-consensus base-pair C:G at position 6. We show that complexes containing T:A or C:G at position 6 exhibit similar overall DNA bend angles and local geometries of DNA kinking. We infer that indirect readout in this system does not involve differences in the geometry of DNA kinking but, rather, solely differences in the energetics of DNA kinking. We further infer that the main determinant of DNA conformation in this system is protein-DNA interaction, and not DNA sequence. Indirect readout of DNA sequence at the primary-kink site in the CAP-DNA complex: DNA binding specificity based on energetics of DNA kinking.,Chen S, Vojtechovsky J, Parkinson GN, Ebright RH, Berman HM J Mol Biol. 2001 Nov 16;314(1):63-74. PMID:11724532[2] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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