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Molecular Basis of Alternating Access Membrane Transport by the Sodium-Hydantoin Transporter Mhp1

DOI: 10.1126/science.1186303 DOI Help
PMID: 20413494 PMID Help

Authors: Tatsuro Shimamura (University College London) , Simone Weyand (Imperial College London, Diamond Light Source) , Oliver Beckstein (University of Oxford) , Nicholas G. Rutherford (University of Leeds) , Jonathan M. Hadden (University of Leeds) , David Sharples (University of Leeds) , Mark S. P. Sansom (University of Oxford) , So Iwata (Diamond Light Source) , Peter J. F. Henderson (University of Leeds) , Alex Cameron (Imperial College London, Diamond Light Source)
Co-authored by industrial partner: No

Type: Journal Paper
Journal: Science , VOL 328

State: Published (Approved)
Published: January 2010

Abstract: The structure of the sodium-benzylhydantoin transport protein Mhp1 from Microbacterium liquefaciens comprises a five-helix inverted repeat, which is widespread among secondary transporters. Here, we report the crystal structure of an inward-facing conformation of Mhp1 at 3.8 angstroms resolution, complementing its previously described structures in outward-facing and occluded states. From analyses of the three structures and molecular dynamics simulations, we propose a mechanism for the transport cycle in Mhp1. Switching from the outward-to the inward-facing state, to effect the inward release of sodium and benzylhydantoin, is primarily achieved by a rigid body movement of transmembrane helices 3, 4, 8, and 9 relative to the rest of the protein. This forms the basis of an alternating access mechanism applicable to many transporters of this emerging superfamily.

Subject Areas: Biology and Bio-materials

Diamond Offline Facilities: Membrane Protein Laboratory (MPL)
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