Seminar

X-Ray Crystallography of Membrane Proteins: Issues & Examples

Professor Michael C. Wiener
Department of Molecular Physiology & Biological Physics
University of Virginia

Monday, April 28, 1997
3:00 pm
3269 Beckman Institute

This presentation will consist of three parts: 1. Why are there so few crystal structures of membrane proteins? Technical and experimental challenges in membrane protein expression and crystallization will be described. 2. The crystal structure of the ion-channel forming bacteriocin colicin Ia [Wiener et al., Nature, 385:461-464, 1997] will be presented. The crystal structure of this intact colicin in its soluble form reveals discrete receptor-binding, translocation and channel-forming domains arrayed along an extraordinarily long (160=86) pair of antiparallel a-helices. This structure answers some, but raise many more, questions about colicin function. 3. Current efforts in the crystallization and structure determination of the human water channel aquaporin-1 will be described. Aquaporins, functioning as passive diffusion-limited pores to dissipate osmotic gradients [Verkman et al., Am. J. Physiol. 270:C12-C30, 1996], are found in a wide range of organisms from bacteria to man. The goal of this work is the determination of the molecular basis of protein-mediated water transport.

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