Structural basis of coactivation of liver receptor homolog-1 by β-catenin
- Proc Natl Acad Sci U S A. 2012 Jan 3;109(1):143-8. doi: 10.1073/pnas.1117036108.
- 1. Department of Biochemistry and Biophysics, University of California San Francisco, 600 16th Street, San Francisco, CA 94158, USA.
We report the three-dimensional structure of a β-catenin armadillo repeat in complex with the liver receptor homolog-1 (LRH-1) ligand binding domain at 2.8 Å resolution as the first structure of β-catenin in complex with any nuclear receptor. The surface of β-catenin that binds LRH-1 partly overlaps defined contact sites for peptide segments of β-catenin partners, including T-cell factor-4. The surface of LRH-1 that engages β-catenin is comprised of helices 1, 9, and 10 and is distinct from known interaction surfaces of LRH-1, including corepressor and coactivator binding sites. Targeted mutagenesis of Amino acids forming both sides of the LRH-1/β-catenin interface reveals that they are essential for stable interactions between these proteins in solution. The LRH-1 binding site in β-catenin is also required for association with Androgen Receptor, providing evidence that the observed LRH-1/β-catenin interaction may be prototypic.