Structural mechanism of plant aquaporin gating
Artikel i vetenskaplig tidskrift, 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.

TRANSPORT

WATER CHANNEL

PROTON EXCLUSION

ELECTRON-DENSITY MAPS

MEMBRANE AQUAPORIN

PROTEIN

DYNAMICS

PERMEATION

GLYCEROL CONDUCTION

MOLECULAR-MECHANISMS

Författare

Susanna Törnroth-Horsefield

Chalmers, Kemi- och bioteknik, Molekylär bioteknik

Yi Wang

University of Illinois at Urbana-Champaign

Kristina Hedfalk

Chalmers, Kemi- och bioteknik, Molekylär bioteknik

U Johanson

Lunds universitet

M Karlsson

Lunds universitet

Emad Tajkhorshid

University of Illinois at Urbana-Champaign

Richard Neutze

Chalmers, Kemi- och bioteknik, Molekylär bioteknik

P Kjellbom

Lunds universitet

Nature

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

Vol. 439 688-694

Ämneskategorier

Biologiska vetenskaper

DOI

10.1038/nature04316