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Structural mechanism of plant aquaporin gating

Susanna Törnroth-Horsefield (Institutionen för kemi- och bioteknik, Molekylär bioteknik) ; Y Wang ; Kristina Hedfalk (Institutionen för kemi- och bioteknik, Molekylär bioteknik) ; U Johanson ; M Karlsson ; E Tajkhorshid ; Richard Neutze (Institutionen för kemi- och bioteknik, Molekylär bioteknik) ; P Kjellbom
Nature (0028-0836). Vol. 439 (2006), 7077, p. 688-694.
[Artikel, refereegranskad vetenskaplig]

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.

Nyckelord: ELECTRON-DENSITY MAPS, WATER CHANNEL, PROTON EXCLUSION, MOLECULAR-MECHANISMS, GLYCEROL CONDUCTION, MEMBRANE AQUAPORIN, DYNAMICS, PROTEIN, PERMEATION, TRANSPORT



Denna post skapades 2007-02-08. Senast ändrad 2015-01-08.
CPL Pubid: 26382

 

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Institutioner (Chalmers)

Institutionen för kemi- och bioteknik, Molekylär bioteknik (2005-2007)

Ämnesområden

Biologiska vetenskaper

Chalmers infrastruktur