Binding site determinants for the LysR-type transcriptional regulator PcaQ in the legume endosymbiont Sinorhizobium meliloti.

ABSTRACT: LysR-type transcriptional regulators represent one of the largest groups of prokaryotic regulators described to date. In the gram-negative legume endosymbiont Sinorhizobium meliloti, enzymes involved in the protocatechuate branch of the beta-ketoadipate pathway are encoded within the pcaDCHGB operon, which is subject to regulation by the LysR-type protein PcaQ. In this work, purified PcaQ was shown to bind strongly (equilibrium dissociation constant, 0.54 nM) to a region at positions -78 to -45 upstream of the pcaD transcriptional start site. Within this region, we defined a PcaQ binding site with dyad symmetry that is required for regulation of pcaD expression in vivo and for binding of PcaQ in vitro. We also demonstrated that PcaQ participates in negative autoregulation by monitoring exp

SUBMITTER: MacLean AM 

PROVIDER: S-EPMC2238203 | biostudies-literature | 2008 Feb

REPOSITORIES: biostudies-literature