Water and ion permeation in bAQP1 and GlpF channels: a kinetic Monte Carlo study

Biophysical Journal
Gennady V Miloshevsky, Peter C Jordan

Abstract

The kinetic Monte Carlo reaction-path-following technique is applied to determine the lowest-energy water pathway and the coordinating amino acids in bAQP1 and GlpF channels, both treated as rigid. In bAQP1, water molecules pass through the pore between the asparagine-proline-alanine (NPA) and selectivity filter (SF) sites one at a time. The water chain is interrupted at the SF where one water forms three stable hydrogen bonds with protein atoms. In this SF, water's conformation depends on the protonation locus of H182. In GlpF, two water molecules bond simultaneously to the NPA asparagines and pass through the SF in zigzag fashion. No water single-file forms in rigid GlpF. To accommodate a single file of waters requires narrowing the GlpF pore. Our results reveal that in both proteins a proposed bipolar water arrangement is thermally disrupted in the NPA region, especially in the cytoplasmic part of the pore. The equilibrium hydrogen-bonded chain is occasionally interrupted in the hydrophobic zones adjacent to the NPA motifs. The permeation of alkali cations through bAQP1 and GlpF is barred due to a large free-energy barrier in the NPA region as well as a large energy barrier blocking entry from the cytoplasm. Permeation of ha...Continue Reading

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Citations

Jun 27, 2007·The Journal of General Physiology·Artem B MamonovJohn C Mathai
Dec 20, 2013·Journal of the Royal Society, Interface·Thomas E DeCoursey, Jonathan Hosler
May 23, 2009·Cryobiology·Ram V Devireddy
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May 23, 2006·Seminars in Nephrology·Melvin E Laski
Jun 14, 2005·Biophysical Journal·Morten Ø JensenCarme Rovira
Jun 25, 2005·The Journal of Chemical Physics·Gennady V Miloshevsky, Peter C Jordan
Jul 3, 2020·Physical Chemistry Chemical Physics : PCCP·Naoki SakashitaKeisuke Saito
Oct 31, 2020·Chembiochem : a European Journal of Chemical Biology·Gabriel José de CarliTiago Campos Pereira

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