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High resolution AFM topographs of the Escherichia coli water channel aquaporin Z

Scheuring, S. and Ringler, P. and Borgnia, M. and Stahlberg, H. and Müller, D. J. and Agre, P. and Engel, A.. (1999) High resolution AFM topographs of the Escherichia coli water channel aquaporin Z. The EMBO journal, Vol. 18, H. 18. pp. 4981-4987.

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Official URL: http://edoc.unibas.ch/dok/A5257674

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Abstract

Aquaporins form a large family of membrane channels involved in osmoregulation. Electron crystallography has shown monomers to consist of six membrane spanning alpha-helices confirming sequence based predictions. Surface exposed loops are the least conserved regions, allowing differentiation of aquaporins. Atomic force microscopy was used to image the surface of aquaporin Z, the water channel of Escherichia coli. Recombinant protein with an N-terminal fragment including 10 histidines was isolated as a tetramer by Ni-affinity chromatography, and reconstituted into two-dimensional crystals with p42(1)2 symmetry. Small crystalline areas with p4 symmetry were found as well. Imaging both crystal types before and after cleavage of the N-termini allowed the cytoplasmic surface to be identified; a drastic change of the cytoplasmic surface accompanied proteolytic cleavage, while the extracellular surface morphology did not change. Flexibility mapping and volume calculations identified the longest loop at the extracellular surface. This loop exhibited a reversible force-induced conformational change.
Faculties and Departments:05 Faculty of Science > Departement Biozentrum > Former Organization Units Biozentrum > Structural Biology (Engel)
05 Faculty of Science > Departement Biozentrum > Structural Biology & Biophysics > Structural Biology (Stahlberg)
UniBasel Contributors:Engel, Andreas H and Stahlberg, Henning
Item Type:Article, refereed
Article Subtype:Research Article
Bibsysno:Link to catalogue
Publisher:Nature Publishing Group
ISSN:0261-4189
Note:Publication type according to Uni Basel Research Database: Journal article
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Last Modified:08 Jun 2012 06:44
Deposited On:22 Mar 2012 13:18

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