Pflügers Archiv - European Journal of Physiology

, Volume 456, Issue 4, pp 651–661

Interactions of lipids with aquaporin-0 and other membrane proteins

  • Richard K. Hite
  • Tamir Gonen
  • Stephen C. Harrison
  • Thomas Walz
Invited Review

DOI: 10.1007/s00424-007-0353-9

Cite this article as:
Hite, R.K., Gonen, T., Harrison, S.C. et al. Pflugers Arch - Eur J Physiol (2008) 456: 651. doi:10.1007/s00424-007-0353-9

Abstract

The structure of aquaporin-0 (AQP0) has recently been determined by electron crystallography of two-dimensional (2D) crystals and by X-ray crystallography of three-dimensional (3D) crystals. The electron crystallographic structure revealed nine lipids per AQP0 monomer, which form an almost complete bilayer. The lipids adopt a wide variety of conformations and tightly fill the space between adjacent AQP0 tetramers. The conformations of the lipid acyl chains appear to be determined not only by the protein surface but also by the acyl chains of adjacent lipid molecules. In the X-ray structure, the hydrophobic region of the protein is surrounded by a detergent micelle, with two ordered detergent molecules per AQP0 monomer. Despite the different environments, the electron crystallographic and X-ray structures of AQP0 are virtually identical, but they differ in the temperature factors of the atoms that either contact the lipids in the 2D crystals or are exposed to detergents in the 3D crystals. The temperature factors are higher in the X-ray structure, suggesting that the detergent-exposed AQP0 residues are less ordered than the corresponding ones contacting lipids in the 2D crystals. An examination of ordered detergent molecules in crystal structures of other aquaporins and of lipid molecules in 2D and 3D crystals of bacteriorhodopsin suggests that the increased conformational variability of detergent-exposed residues compared to lipid-contacting residues is a general feature.

Keywords

Membrane proteinAquaporin-0Lipid–protein interactionsElectron crystallographyX-ray crystallography

Abbreviations

AQP0

aquaporin-0

2D

two-dimensional

3D

three-dimensional

LCP

lipidic cubic phase

bR

bacteriorhodopsin

DMPC

dimyrostylphosphatidylcholine

PC

phosphatidylcholine

Supplementary material

424_2007_353_Fig1_ESM.gif (98 kb)
Supplementary Fig. 1

(GIF 97.8 kb)

424_2007_353_Fig1_ESM.tif (3.8 mb)
High resolution image file (TIFF 3.80 MB)

Copyright information

© Springer-Verlag 2007

Authors and Affiliations

  • Richard K. Hite
    • 1
  • Tamir Gonen
    • 2
  • Stephen C. Harrison
    • 3
  • Thomas Walz
    • 1
  1. 1.Department of Cell BiologyHarvard Medical SchoolBostonUSA
  2. 2.Department of BiochemistryUniversity of WashingtonSeattleUSA
  3. 3.The Jack and Eileen Connors Structural Biology Laboratory, Harvard Medical School, Department of Biological Chemistry and Molecular PharmacologyHoward Hughes Medical InstituteBostonUSA