6POJ

STRUCTURAL REFINEMENT OF AQUAPORIN 1 VIA SSNMR

Summary for 6POJ

• Entry DOI: 10.2210/pdb6poj/pdb
• NMR Information: BMRB: 26805
• Descriptor: Aquaporin-1 (1 entity in total)
• Functional Keywords: transport protein
• Biological source: Homo sapiens (Human)
• Total number of polymer chains: 1
• Total formula weight: 31235.78

Authors

Dingwell, D.A.,Brown, L.S.,Ladizhansky, V. (deposition date: 2019-07-04, release date: 2019-10-02, Last modification date: 2024-05-15)

Primary citation

Dingwell, D.A.,Brown, L.S.,Ladizhansky, V.
Structure of the Functionally Important Extracellular Loop C of Human Aquaporin 1 Obtained by Solid-State NMR under Nearly Physiological Conditions.
J.Phys.Chem.B, 123:7700-7710, 2019

PubMed Abstract: Human aquaporin 1 (hAQP1) is the first discovered selective water channel present in lipid membranes of multiple types of cells. Several structures of hAQP1 and its bovine homolog have been obtained by electron microscopy and X-ray crystallography, giving a consistent picture of the transmembrane domain with the water-conducting pore. The transmembrane domain is formed by six full helices and two half-helices, which form a central constriction with conserved asparagine-proline-alanine motifs. Another constriction, the aromatic/arginine (ar/R) filter, is found close to the extracellular surface, and includes aromatic residues and a conserved arginine (Arg-195). Although the existing crystal structures largely converge on the location of helical segments, they differ in details of conformation of the longest extracellular loop C and its interactions with the ar/R filter (in particular, with Arg-195). Here, we use solid-state nuclear magnetic resonance to determine multiple interatomic distances, and come up with a refined structural model for hAQP1, which represents a physiologically relevant state predominant at noncryogenic temperatures in a lipid environment. The model clearly disambiguates the position of the Arg-195 sidechain disputed previously and shows a number of interactions for loop C, both with the ar/R filter and a number of other residues on the extracellular side of hAQP1.

PubMed: 31411472
DOI: 10.1021/acs.jpcb.9b06430

Experimental method

SOLID-STATE NMR