Secondary structure of the lac repressor DNA-binding domain by two-dimensional 1H nuclear magnetic resonance in solution.

Abstract

A recently proposed approach for spatial structure determination in noncrystalline proteins by NMR was applied to the lac repressor DNA-binding domain [in Escherichia coli]. On the basis of sequence-specific 1H NMR assignments, the location of .alpha.-helicesin the amino acid sequence was determined from nuclear Overhauser enhancement data and from amide proton exchange studies. These investigations provide detailed experimental data on the structure of a noncrystalline DNA-binding protein. Evidently, sequence-specific interactions between lac repressor and DNA are mediated by a particular lac repressor and DNA are mediated by a particular spatial rearrangement of 2 .alpha.-helices common to various different DNA-binding proteins.