A Dynamic Protein-Protein Coupling between the TonB-Dependent Transporter FhuA and TonB.

ABSTRACT: Bacterial outer membrane TonB-dependent transporters function by executing cycles of binding and unbinding to the inner membrane protein TonB. In the vitamin B₁₂ transporter BtuB and the ferric citrate transporter FecA, substrate binding increases the periplasmic exposure of the Ton box, an energy-coupling segment. This increased exposure appears to enhance the affinity of the transporter for TonB. Here, continuous wave and pulse EPR spectroscopy were used to examine the state of the Ton box in the Escherichia coli ferrichrome transporter FhuA. In its apo state, the Ton box of FhuA samples a broad range of positions and multiple conformational substates. When bound to ferrichrome, the Ton box does not extend further into the periplasm, although the structural states sampled by t

SUBMITTER: Sarver JL 

PROVIDER: S-EPMC5811355 | biostudies-literature | 2018 Feb

REPOSITORIES: biostudies-literature