6tyi
ExbB-ExbD complex in MSP1E3D1 nanodiscExbB-ExbD complex in MSP1E3D1 nanodisc
Structural highlights
Function[EXBB_ECOLI] Involved in the TonB-dependent energy-dependent transport of various receptor-bound substrates. Protects ExbD from proteolytic degradation and functionally stabilizes TonB. [EXBD_ECOLI] Involved in the TonB-dependent energy-dependent transport of various receptor-bound substrates. Publication Abstract from PubMedThe TonB-ExbB-ExbD molecular motor harnesses the proton motive force across the bacterial inner membrane to couple energy to transporters at the outer membrane, facilitating uptake of essential nutrients such as iron and cobalamine. TonB physically interacts with the nutrient-loaded transporter to exert a force that opens an import pathway across the outer membrane. Until recently, no high-resolution structural information was available for this unique molecular motor. We published the first crystal structure of ExbB-ExbD in 2016 and showed that five copies of ExbB are arranged as a pentamer around a single copy of ExbD. However, our spectroscopic experiments clearly indicated that two copies of ExbD are present in the complex. To resolve this ambiguity, we used single-particle cryo-electron microscopy to show that the ExbB pentamer encloses a dimer of ExbD in its transmembrane pore, and not a monomer as previously reported. The revised stoichiometry has implications for motor function. Cryo-EM structure of the bacterial Ton motor subcomplex ExbB-ExbD provides information on structure and stoichiometry.,Celia H, Botos I, Ni X, Fox T, De Val N, Lloubes R, Jiang J, Buchanan SK Commun Biol. 2019 Oct 4;2:358. doi: 10.1038/s42003-019-0604-2. eCollection 2019. PMID:31602407[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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