Projection structure of a member of the amino acid/polyamine/organocation transporter superfamily

Casagrande, F. and Ratera, M. and Schenk, A. D. and Chami, M. and Valencia, E. and Lopez, J. M. and Torrents, D. and Engel, A. and Palacin, M. and Fotiadis, D.. (2008) Projection structure of a member of the amino acid/polyamine/organocation transporter superfamily. Journal of biological chemistry, Vol. 283, H. 48. pp. 33240-33248.

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Official URL: http://edoc.unibas.ch/dok/A5262438

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The l-arginine/agmatine antiporter AdiC is a key component of the arginine-dependent extreme acid resistance system of Escherichia coli. Phylogenetic analysis indicated that AdiC belongs to the amino acid/polyamine/organocation (APC) transporter superfamily having sequence identities of 15-17% to eukaryotic and human APC transporters. For functional and structural characterization, we cloned, overexpressed, and purified wild-type AdiC and the point mutant AdiC-W293L, which is unable to bind and consequently transport l-arginine. Purified detergent-solubilized AdiC particles were dimeric. Reconstitution experiments yielded two-dimensional crystals of AdiC-W293L diffracting beyond 6 A resolution from which we determined the projection structure at 6.5 A resolution. The projection map showed 10-12 density peaks per monomer and suggested mainly tilted helices with the exception of one distinct perpendicular membrane spanning alpha-helix. Comparison of AdiC-W293L with the projection map of the oxalate/formate antiporter from Oxalobacter formigenes, a member from the major facilitator superfamily, indicated different structures. Thus, two-dimensional crystals of AdiC-W293L yielded the first detailed view of a transport protein from the APC superfamily at sub-nanometer resolution.
Faculties and Departments:05 Faculty of Science > Departement Biozentrum > Former Organization Units Biozentrum > Structural Biology (Engel)
UniBasel Contributors:Engel, Andreas H and Chami, Mohamed
Item Type:Article, refereed
Article Subtype:Research Article
Publisher:American Society of Biological Chemists
Note:Publication type according to Uni Basel Research Database: Journal article
Last Modified:22 Mar 2012 14:21
Deposited On:22 Mar 2012 13:24

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