Structural evidence for induced fit and a mechanism for sugar/H+ symport in LacY

TY - JOUR

T1 - Structural evidence for induced fit and a mechanism for sugar/H+ symport in LacY

AU - Mirza, Osman Asghar

AU - Guan, Lan

AU - Verner, Gill

AU - Iwata, So

AU - Kaback, H Ronald

PY - 2006/3/22

Y1 - 2006/3/22

N2 - Cation-coupled active transport is an essential cellular process found ubiquitously in all living organisms. Here, we present two novel ligand-free X-ray structures of the lactose permease (LacY) of Escherichia coli determined at acidic and neutral pH, and propose a model for the mechanism of coupling between lactose and H+ translocation. No sugar-binding site is observed in the absence of ligand, and deprotonation of the key residue Glu269 is associated with ligand binding. Thus, substrate induces formation of the sugar-binding site, as well as the initial step in H+ transduction.

AB - Cation-coupled active transport is an essential cellular process found ubiquitously in all living organisms. Here, we present two novel ligand-free X-ray structures of the lactose permease (LacY) of Escherichia coli determined at acidic and neutral pH, and propose a model for the mechanism of coupling between lactose and H+ translocation. No sugar-binding site is observed in the absence of ligand, and deprotonation of the key residue Glu269 is associated with ligand binding. Thus, substrate induces formation of the sugar-binding site, as well as the initial step in H+ transduction.

KW - Binding Sites

KW - Escherichia coli

KW - Escherichia coli Proteins

KW - Hydrogen-Ion Concentration

KW - Ion Transport

KW - Lactose

KW - Ligands

KW - Monosaccharide Transport Proteins

KW - Protein Conformation

KW - Substrate Specificity

KW - Symporters

KW - X-Ray Diffraction

U2 - 10.1038/sj.emboj.7601028

DO - 10.1038/sj.emboj.7601028

M3 - Journal article

C2 - 16525509

SN - 0261-4189

VL - 25

SP - 1177

EP - 1183

JO - E M B O Journal

JF - E M B O Journal

IS - 6

ER -