Structural mechanism of plant aquaporin gating
Journal article, 2006

Plants counteract fluctuations in water supply by regulating all aquaporins in the cell plasma membrane. Channel closure results either from the dephosphorylation of two conserved serine residues under conditions of drought stress, or from the protonation of a conserved histidine residue following a drop in cytoplasmic pH due to anoxia during flooding. Here we report the X-ray structure of the spinach plasma membrane aquaporin SoPIP2; 1 in its closed conformation at 2.1 angstrom resolution and in its open conformation at 3.9 angstrom resolution, and molecular dynamics simulations of the initial events governing gating. In the closed conformation loop D caps the channel from the cytoplasm and thereby occludes the pore. In the open conformation loop D is displaced up to 16 angstrom and this movement opens a hydrophobic gate blocking the channel entrance from the cytoplasm. These results reveal a molecular gating mechanism which appears conserved throughout all plant plasma membrane aquaporins.

PERMEATION

TRANSPORT

PROTEIN

ELECTRON-DENSITY MAPS

MOLECULAR-MECHANISMS

WATER CHANNEL

PROTON EXCLUSION

MEMBRANE AQUAPORIN

GLYCEROL CONDUCTION

DYNAMICS

Author

Susanna Törnroth-Horsefield

Chalmers, Chemical and Biological Engineering, Molecular Biotechnology

Yi Wang

University of Illinois

Kristina Hedfalk

Chalmers, Chemical and Biological Engineering, Molecular Biotechnology

U Johanson

Lund University

M Karlsson

Lund University

Emad Tajkhorshid

University of Illinois

Richard Neutze

Chalmers, Chemical and Biological Engineering, Molecular Biotechnology

P Kjellbom

Lund University

Nature

0028-0836 (ISSN) 1476-4687 (eISSN)

Vol. 439 7077 688-694

Subject Categories

Biological Sciences

DOI

10.1038/nature04316

More information

Latest update

7/4/2018 6