Catabolite activator protein (CAP)PDB ID: 1CGP
CAP is activated by cyclic AMP and then stimulates the synthesis of enzymes that break down food. This structure includes the protein and a short piece of DNA, which is sharply bent by the protein.
Crystal structure of a CAP-DNA complex: the DNA is bent by 90 degrees.
Schultz, S.C., Shields, G.C., Steitz, T.A.
Journal: (1991) Science 253: 1001-1007