Format

Send to

Choose Destination
Proc Natl Acad Sci U S A. 2007 Sep 25;104(39):15294-8. Epub 2007 Sep 19.

Structural determination of wild-type lactose permease.

Author information

1
Department of Physiology, University of California, Los Angeles, CA 90095-1662, USA.

Abstract

Here we describe an x-ray structure of wild-type lactose permease (LacY) from Escherichia coli determined by manipulating phospholipid content during crystallization. The structure exhibits the same global fold as the previous x-ray structures of a mutant that binds sugar but cannot catalyze translocation across the membrane. LacY is organized into two six-helix bundles with twofold pseudosymmetry separated by a large interior hydrophilic cavity open only to the cytoplasmic side and containing the side chains important for sugar and H(+) binding. To initiate transport, binding of sugar and/or an H(+) electrochemical gradient increases the probability of opening on the periplasmic side. Because the inward-facing conformation represents the lowest free-energy state, the rate-limiting step for transport may be the conformational change leading to the outward-facing conformation.

PMID:
17881559
PMCID:
PMC2000551
DOI:
10.1073/pnas.0707688104
[Indexed for MEDLINE]
Free PMC Article

Supplemental Content

Full text links

Icon for HighWire Icon for PubMed Central
Loading ...
Support Center