Sammanfattning

Active transport of substrates across cytoplasmic membranes is of great physiological, medical and pharmaceutical importance. The glycerol-3-phosphate (G3P) transporter (GlpT) of the E. coli inner membrane is a secondary active antiporter from the ubiquitous major facilitator superfamily that couples the import of G3P? to the efflux of inorganic phosphate (Pi) down its concentration gradient. Integrating information from a novel combination of structural, molecular dynamics simulations and biochemical studies, we identify the residues involved directly in binding of substrate to the inward-facing conformation of GlpT, thus defining the structural basis for the substrate-specificity of this transporter. The substrate binding mechanism involves protonation of a histidine residue at the binding site. Furthermore, our data suggest that the formation and breaking of inter- and intradomain salt bridges control the conformational change of the transporter that accompanies substrate translocation across the membrane. The mechanism we propose may be a paradigm for organophosphate:phosphate antiporters. (c) 2008 Elsevier Ltd. All rights reserved.

Nyckelord

antiporter; membrane transport; major facilitator superfamily; molecular dynamics simulations; secondary active transport

Publicerad i

Journal of Molecular Biology
2008, Volym: 378, nummer: 4, sidor: 828-839
Utgivare: ACADEMIC PRESS LTD ELSEVIER SCIENCE LTD

SLU författare

• Huang Almqvist, Yafei

  • Institutionen för molekylärbiologi, Sveriges lantbruksuniversitet
    

UKÄ forskningsämne

Biokemi och molekylärbiologi


Publikationens identifierare

DOI: https://doi.org/10.1016/j.jmb.2008.03.029

Permanent länk till denna sida (URI)

https://res.slu.se/id/publ/17888