Opening and closing of the periplasmic gate in lactose permease
- 11 March 2008
- journal article
- Published by Proceedings of the National Academy of Sciences in Proceedings of the National Academy of Sciences of the United States of America
- Vol. 105 (10), 3774-3778
- https://doi.org/10.1073/pnas.0800825105
Abstract
X-ray crystal structures of lactose permease (LacY) reveal pseudosymmetrically arranged N- and C-terminal six-transmembrane helix bundles surrounding a deep internal cavity open on the cytoplasmic side and completely closed on the periplasmic side. The residues essential for sugar recognition and H(+) translocation are located at the apex of the cavity and are inaccessible from the outside. On the periplasmic side, helices I/II and VII from the N- and C- six helix bundles, respectively, participate in sealing the cavity from the outside. Three paired double-Cys mutants-Ile-40 --> Cys/Asn-245 --> Cys, Thr-45 --> Cys/Asn-245 --> Cys, and Ile-32 --> Cys/Asn-245 --> Cys-located in the interface between helices I/II and VII on the periplasmic side of LacY were constructed. After cross-linking with homobifunctional reagents less than approximately 15 A in length, all three mutants lose the ability to catalyze lactose transport. Strikingly, however, full or partial activity is observed when cross-linking is mediated by flexible reagents greater than approximately 15 A in length. The results provide direct support for the argument that transport via LacY involves opening and closing of a large periplasmic cavity.Keywords
This publication has 46 references indexed in Scilit:
- Site-directed Alkylation of LacY: Effect of the Proton Electrochemical GradientJournal of Molecular Biology, 2007
- Sugar binding induces an outward facing conformation of LacYProceedings of the National Academy of Sciences of the United States of America, 2007
- Polarizable Empirical Force Field for the Primary and Secondary Alcohol Series Based on the Classical Drude ModelJournal of Chemical Theory and Computation, 2007
- Single-molecule FRET reveals sugar-induced conformational dynamics in LacYProceedings of the National Academy of Sciences of the United States of America, 2007
- Site-directed alkylation and the alternating access model for LacYProceedings of the National Academy of Sciences of the United States of America, 2007
- Structural evidence for induced fit and a mechanism for sugar/H+ symport in LacYThe EMBO Journal, 2006
- Efficiency and power in genetic association studiesNature Genetics, 2005
- Scalable molecular dynamics with NAMDJournal of Computational Chemistry, 2005
- All-Atom Empirical Potential for Molecular Modeling and Dynamics Studies of ProteinsThe Journal of Physical Chemistry B, 1998
- VMD: Visual molecular dynamicsJournal of Molecular Graphics, 1996