Biology Department Seminar

"Harnessing Photosynthetic Bacteria for the Heterologous Expression of Membrane Proteins"

Presented by Deborah Hanson, Biosciences Division, Argonne National Laboratory, Argonne, IL

Friday, June 20, 2008, 11:00 am — John Dunn Seminar Room, Bldg. 463

The functions performed by membrane proteins are essential for all organisms. Despite the fact that they represent approximately 30% of every genome and comprise more than 60% of all drug targets, only about 100 unique, unrelated membrane protein structures have been determined to date, in contrast with unique, unrelated structures representing more than 8100 soluble protein families. This field has suffered because it is difficult to obtain quantities of pure, native membrane proteins that are adequate for structural and functional analyses. To approach this problem, we have employed the Rhodobacter species of photosynthetic bacteria -- which is characterized by an inducible intracytoplasmic membrane (ICM) -- for the heterologous expression of membrane proteins. Compartmentalization of an expressed membrane protein to the Rhodobacter ICM suggests strongly that it assumes a structure that directs proper insertion into the lipid bilayer. Activity assays and circular dichroism spectra have been used to demonstrate functional and structural integrity of heterologous proteins following their purification from Rhodobacter membranes. Our results also underscore this organism's utility in the assembly of membrane proteins with complex cofactors. This expression system puts to task, in a novel way, this photosynthetic species and the membranes it produces naturally in order to harness this machinery for the efficient production of foreign membrane proteins for a variety of structural and functional experiments.

Hosted by: Carl Anderson

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