4x5n
From Proteopedia
Crystal structure of SemiSWEET in the inward-open and outward-open conformations
Structural highlights
FunctionSWEET_ECOU3 The homodimer mediates transmembrane sugar transport down a concentration gradient. Transport is probably effected by rocking-type movements, where a cargo-binding cavity opens first on one and then on the other side of the membrane.[1] Publication Abstract from PubMedSWEET family proteins mediate sugar transport across biological membranes and play crucial roles in plants and animals. The SWEETs and their bacterial homologues, the SemiSWEETs, are related to the PQ-loop family, which is characterized by highly conserved proline and glutamine residues (PQ-loop motif). Although the structures of the bacterial SemiSWEETs were recently reported, the conformational transition and the significance of the conserved motif in the transport cycle have remained elusive. Here we report crystal structures of SemiSWEET from Escherichia coli, in the both inward-open and outward-open states. A structural comparison revealed that SemiSWEET undergoes an intramolecular conformational change in each protomer. The conserved PQ-loop motif serves as a molecular hinge that enables the 'binder clip-like' motion of SemiSWEET. The present work provides the framework for understanding the overall transport cycles of SWEET and PQ-loop family proteins. Structural basis for the facilitative diffusion mechanism by SemiSWEET transporter.,Lee Y, Nishizawa T, Yamashita K, Ishitani R, Nureki O Nat Commun. 2015 Jan 19;6:6112. doi: 10.1038/ncomms7112. PMID:25598322[2] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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