The 5A structure of heterologously expressed plant aquaporin SoPIP2;1

Kukulski, W. and Schenk, A. D. and Johanson, U. and Braun, T. and de Groot, B. L. and Fotiadis, D. and Kjellbom, P. and Engel, A.. (2005) The 5A structure of heterologously expressed plant aquaporin SoPIP2;1. Journal of molecular biology, Vol. 350, H. 4. pp. 611-616.

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Official URL: http://edoc.unibas.ch/dok/A5257637

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SoPIP2;1 is one of the major integral proteins in spinach leaf plasma membranes. In the Xenopus oocyte expression system its water channel activity is regulated by phosphorylation at the C terminus and in the first cytosolic loop. To assess its structure, SoPIP2;1 was heterologously expressed in Pichia pastoris as a His-tagged protein and in the non-tagged form. Both forms were reconstituted into 2D crystals in the presence of lipids. Tubular crystals and double-layered crystalline sheets of non-tagged SoPIP2;1 were observed and analyzed by cryo-electron microscopy. Crystalline sheets were highly ordered and diffracted electrons to a resolution of 2.96A. High-resolution projection maps of tilted specimens provided a 3D structure at 5A resolution. Superposition of the SoPIP2;1 potential map with the atomic model of AQP1 demonstrates the generally well conserved overall structure of water channels. Differences concerning the extracellular loop A explain the particular crystal contacts between oppositely oriented membrane sheets of SoPIP2;1 2D crystals, and may have a function in rapid volume changes observed in stomatal guard cells or mesophyll protoplasts. This crystal packing arrangement provides access to the phosphorylated C terminus as well as the loop B phosphorylation site for studies of channel gating.
Faculties and Departments:05 Faculty of Science > Departement Biozentrum > Former Organization Units Biozentrum > Structural Biology (Engel)
UniBasel Contributors:Engel, Andreas H
Item Type:Article, refereed
Article Subtype:Research Article
Note:Publication type according to Uni Basel Research Database: Journal article
Last Modified:22 Mar 2012 14:20
Deposited On:22 Mar 2012 13:18

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