6N1G

Crystal structure of Aquaglyceroporin AQP7

Summary for 6N1G

• Entry DOI: 10.2210/pdb6n1g/pdb
• Related: 1J4N 1Z98 3D9S 3GD8
• Descriptor: Aquaporin-7, GLYCEROL (2 entities in total)
• Functional Keywords: aquaglyceroporin, water, glycerol, structural protein
• Biological source: Homo sapiens (Human)
• Total number of polymer chains: 4
• Total formula weight: 165503.08

Authors

Vahedi-Faridi, A.,Lodowski, D.,Kowatz, T. (deposition date: 2018-11-08, release date: 2019-11-13, Last modification date: 2023-10-11)

Primary citation

Moss, F.J.,Mahinthichaichan, P.,Lodowski, D.T.,Kowatz, T.,Tajkhorshid, E.,Engel, A.,Boron, W.F.,Vahedi-Faridi, A.
Aquaporin-7: A Dynamic Aquaglyceroporin With Greater Water and Glycerol Permeability Than Its Bacterial Homolog GlpF.
Front Physiol, 11:728-728, 2020

PubMed Abstract: oocytes expressing human aquaporin-7 (AQP7) exhibit greater osmotic water permeability and H-glycerol uptake vs. those expressing the bacterial glycerol facilitator GlpF. AQP7-expressing oocytes exposed to increasing extracellular [glycerol] under isosmolal conditions exhibit increasing swelling rates, whereas GlpF-expressing oocytes do not swell at all. To provide a structural basis for these observed physiological differences, we performed X-ray crystallographic structure determination of AQP7 and molecular-dynamics simulations on AQP7 and GlpF. The structure reveals AQP7 tetramers containing two monomers with 3 glycerols, and two monomers with 2 glycerols in the pore. In contrast to GlpF, no glycerol is bound at the AQP7 selectivity filter (SF), comprising residues F74, G222, Y223, and R229. The AQP7 SF is resolved in its closed state because F74 blocks the passage of small solutes. Molecular dynamics simulations demonstrate that F74 undergoes large and rapid conformational changes, allowing glycerol molecules to permeate without orientational restriction. The more rigid GlpF imposes orientational constraints on glycerol molecules passing through the SF. Moreover, GlpF-W48 (analogous to AQP7-F74) undergoes rare but long-lasting conformational changes that block the pore to HO and glycerol.

PubMed: 32695023
DOI: 10.3389/fphys.2020.00728

Experimental method

X-RAY DIFFRACTION (3.995 Å)