Related Experiment Video
Updated: Jul 28, 2026

Iterative Optimization of DNA Duplexes for Crystallization of SeqA-DNA Complexes
Published on: November 1, 2012
Crystal structure of a CAP-DNA complex: the DNA is bent by 90 degrees
S C Schultz1, G C Shields, T A Steitz
1Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, CT 06511.
Abstract:
The 3 angstrom resolution crystal structure of the Escherichia coli catabolite gene activator protein (CAP) complexed with a 30-base pair DNA sequence shows that the DNA is bent by 90 degrees. This bend results almost entirely from two 40 degrees kinks that occur between TG/CA base pairs at positions 5 and 6 on each side of the dyad axis of the complex. DNA sequence discrimination by CAP derives both from sequence-dependent distortion of the DNA helix and from direct hydrogen-bonding interactions between three protein side chains and the exposed edges of three base pairs in the major groove of the DNA. The structure of this transcription factor--DNA complex provides insights into possible mechanisms of transcription activation.
Related Concept Videos
The DNA Helix
The DNA Helix
DNA as a Genetic Template
DNA Helicases
The DNA Helix
Nucleic Acid Structure
DNA Structure
DNA has a double-helix structure. The...

