Structural basis for conductance by the archaeal aquaporin AqpM at 1.68 Å
Embargo until
Date
2005-12-27
Journal Title
Journal ISSN
Volume Title
Publisher
National Academy of Sciences
Abstract
To explore the structural basis of the unique selectivity spectrum and conductance of the transmembrane channel protein AqpM from the archaeon Methanothermobacter marburgensis, we determined the structure of AqpM to 1.68-A resolution by x-ray crystallography. The structure establishes AqpM as being in a unique subdivision between the two major subdivisions of aquaporins, the water-selective aquaporins, and the water-plus-glycerol-conducting aquaglyceroporins. In AqpM, isoleucine replaces a key histidine residue found in the lumen of water channels, which becomes a glycine residue in aquaglyceroporins. As a result of this and other side-chain substituents in the walls of the channel, the channel is intermediate in size and exhibits differentially tuned electrostatics when compared with the other subfamilies.
Description
Keywords
Archaea/metabolism, Aquaporins/chemistry
Citation
Proc Natl Acad Sci U S A. 2005 Dec 27;102(52):18932-7. Epub 2005 Dec 16. http://www.pnas.org/content/102/52/18932.full