Refolding dynamics of a beta-barrel membrane protein: OmpA

INOR 260

Gitrada Arjara, gitrada@caltech.edu1, Judy E Kim2, J. H. Richards1, H. B. Gray, hbgray@caltech.edu1, and Jay R. Winkler1. (1) Department of Chemistry, California Institute of Technology, Pasadena, CA 91125, (2) Department of Chemistry, University of California, San Diego, Urey Hall Addition, 3040B, 9500 Gilman Drive, MC 0314, La Jolla, CA 92093
The amphiphilic, beta-barrel outer membrane protein A (OmpA) from E. coli refolds and inserts directly into lipid vesicles or micelles from a fully denatured state in aqueous urea solution. Steady-state and time-resolved fluorescence measurements have been performed using single tryptophan mutants of full-length OmpA (325 residues) and the truncated, transmembrane domain (176 residues). In initial studies, a dansyl fluorophore has been used to label a mutant Cys residue 175 in both full-length and truncated OmpA forms of the single-tryptophan variants. We intend to measure rates of fluorescence energy transfer from tryptophan to dansyl as the polypeptide folds and inserts into micelles and lipid bilayers. These studies will shed light on OmpA folding dynamics; in particular, they should reveal the role of the C-terminus in the mechanism.
 

Frontiers of Inorganic Chemistry: The Gray Areas
7:00 PM-10:00 PM, Sunday, 10 September 2006 Moscone Center -- Hall D, Poster

Sci-Mix
8:00 PM-10:00 PM, Monday, 11 September 2006 Moscone Center -- Hall D, Sci-Mix

Division of Inorganic Chemistry

The 232nd ACS National Meeting, San Francisco, CA, September 10-14, 2006