Investigating the binding specificity and thermodynamics of the nuclear receptor retinoid X receptor variants

BIOL 37

Terry J Watt, terry.watt@chemistry.gatech.edu, School of Chemistry & Biochemistry, Georgia Institute of Technology, Atlanta, GA 30332-0400 and Donald F Doyle, donald.doyle@chemistry.gatech.edu, School of Chemistry and Biochemistry, Georgia Institute of Technology, Atlanta, GA 30332-0400.
We previously engineered a variety of functional retinoid X receptor variants that bind a synthetic ligand (LG335) which does not activate the wild-type receptor. We overexpressed and purified the wild-type receptor and four of the variant receptors representing a range of activation profiles and functional selectivities. For each receptor, we determined the binding constants for the wild-type ligand (9-cis retinoic acid), LG335, and a model peptide containing an LXXLL coactivator binding motif. We also measured the thermodynamic stabilities of the wild-type receptor and variants in response to heat and guanidine hydrochloride. While providing new information about the wild-type receptor, these analyses also suggest that the active holo-nuclear receptor conformation is easier to perturb through mutagenesis than is the ligand-receptor affinity. The data also suggest that mutagenesis restricted to the binding pocket can have significant impact on receptor thermal stability.
 

Protein Structure and Folding
4:30 PM-6:30 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 Biological Chemistry

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