Ligand-induced structural changes in the Escherichia coli ferric citrate transporter reveal modes for regulating protein-protein interactions.

ABSTRACT: Outer-membrane TonB-dependent transporters, such as the Escherichia coli ferric citrate transporter FecA, interact with the inner-membrane protein TonB through an energy-coupling segment termed the Ton box. In FecA, which regulates its own transcription, the Ton box is preceded by an N-terminal extension that interacts with the inner-membrane protein FecR. Here, site-directed spin labeling was used to examine the structural basis for transcriptional signaling and Ton box regulation in FecA. EPR spectroscopy indicates that regions of the N-terminal domain are in conformational exchange, consistent with its role as a protein binding element; however, the local fold and dynamics of the domain are not altered by substrate or TonB. Distance restraints derived from pulse EPR were used to generat

SUBMITTER: Mokdad A 

PROVIDER: S-EPMC3472153 | biostudies-literature | 2012 Nov

REPOSITORIES: biostudies-literature