title: The alternating access mechanism of transport as observed in the sodium-hydantoin transporter Mhp1.
abstract: Secondary active transporters move molecules across cell membranes by coupling this process to the energetically favourable downhill movement of ions or protons along an electrochemical gradient. They function by the alternating access model of transport in which, through conformational changes, the substrate binding site alternately faces either side of the membrane. Owing to the difficulties in obtaining the crystal structure of a single transporter in different conformational states, relatively little structural information is known to explain how this process occurs. Here, the structure of the sodium-benzylhydantoin transporter, Mhp1, from Microbacterium liquefaciens, has been determined in three conformational states; from this a mechanism is proposed for switching from the outward-facing open conformation through an occluded structure to the inward-facing open state.
authors.affiliation: Division of Molecular Biosciences, Membrane Protein Crystallography Group, Imperial College, London SW7 2AZ, UK.
authors.forename: Simone
authors.initials: S
authors.lastname: Weyand
authors.forename: Tatsuro
authors.initials: T
authors.lastname: Shimamura
authors.forename: Oliver
authors.initials: O
authors.lastname: Beckstein
authors.forename: Mark S P
authors.initials: MS
authors.lastname: Sansom
authors.forename: So
authors.initials: S
authors.lastname: Iwata
authors.forename: Peter J F
authors.initials: PJ
authors.lastname: Henderson
authors.forename: Alexander D
authors.initials: AD
authors.lastname: Cameron
mesh_terms: D000192:Actinomycetales / Q000737:chemistry / Q000378:metabolism; D001665:Binding Sites; D006827:Hydantoins / Q000378:metabolism; D017136:Ion Transport; D012964:Sodium / Q000378:metabolism; D027981:Symporters / Q000737:chemistry / Q000378:metabolism*
chemical_list: D006827:Hydantoins; D027981:Symporters; C031427:5-benzylhydantoin; D012964:Sodium