The structure of GlpF, a glycerol conducting channel

Dax Fu, Andrew Libson, Robert Stroud

Research output: Contribution to journalArticlepeer-review

Abstract

The passage of water or small neutral solutes across the cell membrane in animals, plants and bacteria is facilitated by a family of homologous membrane channels, variously known as aquaporins though perhaps more correctly as aquaglyceroporins. The glycerol facilitator (GlpF) is a 28 kDa aquaglyceroporin that catalyses transmembrane diffusion of glycerol and certain linear polyhydric alcohols in Escherichia coli. X-ray crystallographic analysis of GlpF to 2.2 Å resolution revealed an α-barrel structure, surrounded by six full-length transmembrane helices and two half-spanning helices that are joined head-to-head in the middle of the membrane. These helices are arranged to a quasi twofold manner relative to the central membrane plane, where highly conserved residues make helix-to-helix contacts that stabilize the relative position and orientation of the helices in the structure. This sequence-structure correlation suggests that the evolutionary divergence of aquaporins and aquaglyceroporins is constrained by a conserved structural framework within which specialized function may be developed. Three glycerol molecules were resolved in the central channel through the GlpF monomer, thereby defining a transmembrane channel for glycerol permeation. The structure of glycerol-GlpF complex provides insight into the chemical basis for transmembrane selective permeability.

Original languageEnglish (US)
Pages (from-to)51-65
Number of pages15
JournalNovartis Foundation Symposium
Volume245
StatePublished - 2002
Externally publishedYes

ASJC Scopus subject areas

  • Medicine(all)

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