Biochemistry I   Spring & Fall Terms

CAP-cAMP-DNA Complex Structure

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  DNA, 1.5 turns
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  Half-site Close-up

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The CAP-cAMP-DNA Complex. A helix-turn-helix (HTH) protein.
The E. coli cAMP Receptor Protein (CRP, a.k.a. CAP) is a transcriptional activator that binds to DNA (shown using the Spacefill display with yellow backbone). The two subunits of the symmetric dimer are shown using the Cartoon display; the cAMP-binding domain is blue and the DNA-binding domain is purple. The cAMP molecules bound to each subunit are shown as Spacefill with CPK coloring. (cf. Fig. 2 of Schultz, et al.)
In the close-up view of protein-DNA interactions in one half-site, amino acid side chains H-bond to the DNA bases as follows: Arg180 to G25; Glu181 to C25; and Arg185 to G27, the helix-turn-helix (HTH) motif is colored magenta within the purple DNA-binding domain. (cf. Fig. 3B of Schultz, et al.)

This structure is described in Schultz SC, Shields GC, Steitz TA (1991) "Crystal structure of a CAP-DNA complex: the DNA is bent by 90 degrees"Science 2531001.     PubMed Abstract.

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11.11.04