Crystal structure of a yeast aquaporin at 1.15 angstrom reveals a novel gating mechanism.
Journal article, 2009
Aquaporins are transmembrane proteins that facilitate the flow of water through cellular membranes. An unusual characteristic of yeast aquaporins is that they frequently contain an extended N terminus of unknown function. Here we present the X-ray structure of the yeast aquaporin Aqy1 from Pichia pastoris at 1.15 A resolution. Our crystal structure reveals that the water channel is closed by the N terminus, which arranges as a tightly wound helical bundle, with Tyr31 forming H-bond interactions to a water molecule within the pore and thereby occluding the channel entrance. Nevertheless, functional assays show that Aqy1 has appreciable water transport activity that aids survival during rapid freezing of P. pastoris. These findings establish that Aqy1 is a gated water channel. Mutational studies in combination with molecular dynamics simulations imply that gating may be regulated by a combination of phosphorylation and mechanosensitivity.
Freezing
Models
Aquaporins
chemistry
metabolism
Tyrosine
Ion Channel Gating
Microbial Viability
Molecular
Secondary
metabolism
Crystallography
Pichia
Biological Transport
chemistry
Water
Structural Homology
Phosphorylation
chemistry
Spinacia oleracea
Protein Structure
Computer Simulation
Protein
X-Ray
Author
Gerhard Fischer
University of Gothenburg
Urszula Kosinska-Eriksson
University of Gothenburg
Camilo Aponte-Santamaría
Madelene Palmgren
University of Gothenburg
Cecilia Geijer
University of Gothenburg
Kristina Hedfalk
University of Gothenburg
Stefan Hohmann
University of Gothenburg
Bert L de Groot
Richard Neutze
University of Gothenburg
Karin Lindkvist-Petersson
University of Gothenburg
PLoS Biology
1544-9173 (ISSN) 1545-7885 (eISSN)
Vol. 7 6 e1000130-Subject Categories
Chemical Sciences
DOI
10.1371/journal.pbio.1000130
PubMed
19529756