Architecture and Selectivity in Aquaporins: 2.5 Å X-Ray Structure of Aquaporin Z

Abstract

Aquaporins are a family of water and small molecule channels found in organisms ranging from bacteria to animals. One of these channels, the E. coli protein aquaporin Z (AqpZ), has been shown to selectively conduct only water at high rates. We have expressed, purified, crystallized, and solved the X-ray structure of AqpZ. The 2.5 A resolution structure of AqpZ suggests aquaporin selectivity results both from a steric mechanism due to pore size and from specific amino acid substitutions that regulate the preference for a hydrophobic or hydrophilic substrate. This structure provides direct evidence on the molecular mechanisms of specificity between water and glycerol in this family of channels from a single species. It is to our knowledge the first atomic resolution structure of a recombinant aquaporin and so provides a platform for combined genetic, mutational, functional, and structural determinations of the mechanisms of aquaporins and, more generally, the assembly of multimeric membrane proteins.

Cited by papers we hold 7

• Molecular characterization of branchial aquaporin 1aa and effects of seawater acclimation, emersion or ammonia exposure on its mRNA expression in the gills, gut, kidney and skin of the freshwater climbing perch, Anabas testudineus. · 2013
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• Gene sets for utilization of primary and secondary nutrition supplies in the distal gut of endangered Iberian lynx. · 2012
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• Structure and stability of the spinach aquaporin SoPIP2;1 in detergent micelles and lipid membranes. · 2011
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• Crystal Structure of a Yeast Aquaporin at 1.15 Å Reveals a Novel Gating Mechanism · 2009
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• Genome-wide analysis of major intrinsic proteins in the tree plant Populus trichocarpa: Characterization of XIP subfamily of aquaporins from evolutionary perspective · 2009
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• Unexpected complexity of the Aquaporin gene family in the moss Physcomitrella patens · 2008
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• Aquaporin-11: a channel protein lacking apparent transport function expressed in brain. · 2006
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