Origins of DNA-binding specificity: role of protein contacts with the DNA backbone.

ABSTRACT: A central question in protein-DNA recognition is the origin of the specificity that permits binding to the correct site in the presence of excess, nonspecific DNA. In the P22 Arc repressor, the Phe-10 side chain is part of the hydrophobic core of the free protein but rotates out to pack against the sugar-phosphate backbone of the DNA in the repressor-operator complex. Characterization of a library of position 10 variants reveals that Phe is the only residue that results in fully active Arc. One class of mutants folds stably but binds operator with reduced affinity; another class is unstable. FV10, one member of the first class, binds operator DNA and nonoperator DNA almost equally well. The affinity differences between FV10 and wild type indicate that each Phe-10 side chain contributes 1.5

SUBMITTER: Schildbach JF 

PROVIDER: S-EPMC15307 | biostudies-literature | 1999 Feb

REPOSITORIES: biostudies-literature