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Cells 2018, 7(11), 207; https://doi.org/10.3390/cells7110207

Molecular Basis of Aquaporin-7 Permeability Regulation by pH

1
Research Institute for Medicines (iMed.ULisboa), Faculty of Pharmacy, Universidade de Lisboa, 1649-003 Lisboa, Portugal
2
Dept. Bioquímica e Biologia Humana, Faculty of Pharmacy, Universidade de Lisboa, 1649-003 Lisboa, Portugal
3
School of Chemistry, Cardiff University, Park Place, Cardiff CF10 3AT, UK
4
Tumour MicroEnvironment Group, Division of Cancer and Genetics, School of Medicine, Cardiff University, Tenovus Building, Cardiff CF14 4XN, UK
5
LEAF, Linking Landscape, Environment, Agriculture and Food, and DRAT, Dept. de Recursos Biológicos, Ambiente e Território, Instituto Superior de Agronomia, Universidade de Lisboa, Tapada da Ajuda, 1349017 Lisboa, Portugal
6
Faculdade de Ciências e Tecnologia, Universidade Nova de Lisboa, 2829-516 Caparica, Portugal
These authors contributed equally to this work.
*
Authors to whom correspondence should be addressed.
Received: 20 October 2018 / Revised: 5 November 2018 / Accepted: 7 November 2018 / Published: 10 November 2018
(This article belongs to the Special Issue Aquaporins)
Full-Text   |   PDF [2798 KB, uploaded 10 November 2018]   |  

Abstract

The aquaglyceroporin AQP7, a family member of aquaporin membrane channels, facilitates the permeation of water and glycerol through cell membranes and is crucial for body lipid and energy homeostasis. Regulation of glycerol permeability via AQP7 is considered a promising therapeutic strategy towards fat-related metabolic complications. Here, we used a yeast aqy-null strain for heterologous expression and functional analysis of human AQP7 and investigated its regulation by pH. Using a combination of in vitro and in silico approaches, we found that AQP7 changes from fully permeable to virtually closed at acidic pH, and that Tyr135 and His165 facing the extracellular environment are crucial residues for channel permeability. Moreover, instead of reducing the pore size, the protonation of key residues changes AQP7’s protein surface electrostatic charges, which, in turn, may decrease glycerol’s binding affinity to the pore, resulting in decreased permeability. In addition, since some pH-sensitive residues are located at the monomer-monomer interface, decreased permeability may result from cooperativity between AQP7’s monomers. Considering the importance of glycerol permeation via AQP7 in multiple pathophysiological conditions, this mechanism of hAQP7 pH-regulation may help the design of selective modulators targeting aquaglyceroporin-related disorders. View Full-Text
Keywords: aquaporin; aquaglyceroporin; AQP7; pH; yeast; regulation; water and glycerol permeability aquaporin; aquaglyceroporin; AQP7; pH; yeast; regulation; water and glycerol permeability
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This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited (CC BY 4.0).

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Mósca, A.F.; de Almeida, A.; Wragg, D.; Martins, A.P.; Sabir, F.; Leoni, S.; Moura, T.F.; Prista, C.; Casini, A.; Soveral, G. Molecular Basis of Aquaporin-7 Permeability Regulation by pH. Cells 2018, 7, 207.

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