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Temperature dependence of protein-water interactions in a gated yeast aquaporin

Journal article
Authors C. Aponte-Santamaria
Gerhard Fischer
Petra Båth
Richard Neutze
B. L. de Groot
Published in Scientific Reports
Volume 7
ISSN 2045-2322
Publication year 2017
Published at Department of Chemistry and Molecular Biology
Language en
Links dx.doi.org/10.1038/s41598-017-04180...
Keywords PHOTOSYNTHETIC REACTION-CENTER, SERIAL FEMTOSECOND CRYSTALLOGRAPHY, MOLECULAR-DYNAMICS SIMULATIONS, PARTICLE MESH EWALD, FORCE-FIELD, MEMBRANE-PROTEIN, STRUCTURAL INSIGHTS, CRYSTAL-STRUCTURE, FREEZE, TOLERANCE, LIPID-BILAYER
Subject categories Biochemistry

Abstract

Regulation of aquaporins is a key process of living organisms to counteract sudden osmotic changes. Aqy1, which is a water transporting aquaporin of the yeast Pichia pastoris, is suggested to be gated by chemo-mechanical stimuli as a protective regulatory-response against rapid freezing. Here, we tested the influence of temperature by determining the X-ray structure of Aqy1 at room temperature (RT) at 1.3 angstrom resolution, and by exploring the structural dynamics of Aqy1 during freezing through molecular dynamics simulations. At ambient temperature and in a lipid bilayer, Aqy1 adopts a closed conformation that is globally better described by the RT than by the low-temperature (LT) crystal structure. Locally, for the blocking-residue Tyr31 and the water molecules inside the pore, both LT and RT data sets are consistent with the positions observed in the simulations at room-temperature. Moreover, as the temperature was lowered, Tyr31 adopted a conformation that more effectively blocked the channel, and its motion was accompanied by a temperature-driven rearrangement of the water molecules inside the channel. We therefore speculate that temperature drives Aqy1 from a loosely-to a tightly-blocked state. This analysis provides high-resolution structural evidence of the influence of temperature on membrane-transport channels.

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