Structure-function studies of DNA binding domain of response regulator KdpE reveals equal affinity interactions at DNA half-sites.

ABSTRACT: Expression of KdpFABC, a K(+) pump that restores osmotic balance, is controlled by binding of the response regulator KdpE to a specific DNA sequence (kdpFABC(BS)) via the winged helix-turn-helix type DNA binding domain (KdpE(DBD)). Exploration of E. coli KdpE(DBD) and kdpFABC(BS) interaction resulted in the identification of two conserved, AT-rich 6 bp direct repeats that form half-sites. Despite binding to these half-sites, KdpE(DBD) was incapable of promoting gene expression in vivo. Structure-function studies guided by our 2.5 Å X-ray structure of KdpE(DBD) revealed the importance of residues R193 and R200 in the α-8 DNA recognition helix and T215 in the wing region for DNA binding. Mutation of these residues renders KdpE incapable of inducing expression of the kdpFABC operon. Detailed

SUBMITTER: Narayanan A 

PROVIDER: S-EPMC3264566 | biostudies-literature | 2012

REPOSITORIES: biostudies-literature