Crystal structure of the met repressor-operator complex at 2.8 A resolution reveals DNA recognition by beta-strands.

Somers, W S; Phillips, S E · Nature · 1992

basic_science · Level V

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Abstract

The crystal structure of the met repressor-operator complex shows two dimeric repressor molecules bound to adjacent sites 8 base pairs apart on an 18-base-pair DNA fragment. Sequence specificity is achieved by insertion of double-stranded antiparallel protein beta-ribbons into the major groove of B-form DNA, with direct hydrogen-bonding between amino-acid side chains and the base pairs. The repressor also recognizes sequence-dependent distortion or flexibility of the operator phosphate backbone, conferring specificity even for inaccessible base pairs.

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