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Structural clues in the sequences of the aquaporins

Heymann, J. B. and Engel, A.. (2000) Structural clues in the sequences of the aquaporins. Journal of molecular biology, Vol. 295, H. 4. pp. 1039-1053.

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Official URL: http://edoc.unibas.ch/dok/A5262369

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Abstract

The large number of sequences available for the aquaporin family represents a valuable source of information to incorporate into three- dimensional structure determination. Phylogenetic analysis was used to define type sequences to avoid extreme over-representation of some subfamilies, and as a measure of the quality of multiple sequence alignment. Inspection of the sequence alignment suggested eight conserved segments that define the core architecture of six transmembrane helices and two functional loops, B and E, projecting into the plane of the membrane. The sum of the core segments and the minimum lengths of the interlinking loops constitute the 208 residues necessary to satisfy the aquaporin architecture. Analysis of hydrophobic and conservation periodicity and of correlated mutations across the alignment indicated the likely assignment and orientation of the helices in the bilayer. This assignment is examined with respect to the structure of the erythrocyte aquaporin 1 determined by electron crystallography. The aquaporin 1 tetramer is described as three rings of helices, each ring with a different exposure to the lipid environment. The sequence analysis clearly suggests that two helices are exposed along their whole lengths, two helices are exposed only at their N termini, and two helices are not exposed to lipid. It is further proposed that, besides loops B and E, the highly conserved motifs on helices 1 and 4, ExxxTxxF/L, could line the water channel.
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
Bibsysno:Link to catalogue
Publisher:Elsevier
ISSN:0022-2836
Note:Publication type according to Uni Basel Research Database: Journal article
Last Modified:22 Mar 2012 14:21
Deposited On:22 Mar 2012 13:23

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