title: Role of Pore-Lining Residues in Defining the Rate of Water Conduction by Aquaporin-0.
abstract: Compared to other aquaporins (AQPs), lens-specific AQP0 is a poor water channel, and its permeability was reported to be pH-dependent. To date, most water conduction studies on AQP0 were performed on protein expressed in Xenopus oocytes, and the results may therefore also reflect effects introduced by the oocytes themselves. Experiments with purified AQP0 reconstituted into liposomes are challenging because the water permeability of AQP0 is only slightly higher than that of pure lipid bilayers. By reconstituting high amounts of AQP0 and using high concentrations of cholesterol to reduce the permeability of the lipid bilayer, we improved the signal-to-noise ratio of water permeability measurements on AQP0 proteoliposomes. Our measurements show that mutation of two pore-lining tyrosine residues, Tyr-23 and Tyr-149 in sheep AQP0, to the corresponding residues in the high-permeability water channel AQP1 have additive effects and together increase the water permeability of AQP0 40-fold to a level comparable to that of AQP1. Molecular dynamics simulations qualitatively support these experimental findings and suggest that mutation of Tyr-23 changes the pore profile at the gate formed by residue Arg-187.
authors.affiliation: Department of Chemical Engineering, Pennsylvania State University, University Park, Pennsylvania.
authors.forename: Patrick O
authors.initials: PO
authors.lastname: Saboe
authors.affiliation: Department of Cell Biology, Harvard Medical School, Boston, Massachusetts.
authors.forename: Chiara
authors.initials: C
authors.lastname: Rapisarda
authors.affiliation: Computational Biomolecular Dynamics Group, Max Planck Institute for Biophysical Chemistry, Göttingen, Germany.
authors.forename: Shreyas
authors.initials: S
authors.lastname: Kaptan
authors.affiliation: Department of Cell Biology, Harvard Medical School, Boston, Massachusetts.
authors.forename: Yu-Shan
authors.initials: YS
authors.lastname: Hsiao
authors.affiliation: Department of Chemical Engineering, Pennsylvania State University, University Park, Pennsylvania.
authors.forename: Samantha R
authors.initials: SR
authors.lastname: Summers
authors.affiliation: Department of Cell Biology, Harvard Medical School, Boston, Massachusetts.
authors.forename: Rita
authors.initials: R
authors.lastname: De Zorzi
authors.affiliation: Department of Cell Biology, Harvard Medical School, Boston, Massachusetts.
authors.forename: Danijela
authors.initials: D
authors.lastname: Dukovski
authors.affiliation: Department of Chemical Engineering, Pennsylvania State University, University Park, Pennsylvania.
authors.forename: Jiaheng
authors.initials: J
authors.lastname: Yu
authors.affiliation: Computational Biomolecular Dynamics Group, Max Planck Institute for Biophysical Chemistry, Göttingen, Germany.
authors.forename: Bert L
authors.initials: BL
authors.lastname: de Groot
authors.affiliation: Department of Chemical Engineering, Pennsylvania State University, University Park, Pennsylvania. Electronic address: manish.kumar@psu.edu.
authors.forename: Manish
authors.initials: M
authors.lastname: Kumar
authors.affiliation: Department of Cell Biology, Harvard Medical School, Boston, Massachusetts. Electronic address: twalz@mail.rockefeller.edu.
authors.forename: Thomas
authors.initials: T
authors.lastname: Walz
mesh_terms: D000818:Animals; D020346:Aquaporins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D001692:Biological Transport; D005136:Eye Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D056004:Molecular Dynamics Simulation; D009154:Mutation; D010539:Permeability; D016062:Porosity; D011487:Protein Conformation; D055550:Protein Stability; D012756:Sheep; D014867:Water / Q000378:metabolism*
chemical_list: D020346:Aquaporins; D005136:Eye Proteins; C030328:aquaporin 0; D014867:Water