Manipulation of reciprocal salt bridges at the heterodimerization interface alters the dimerization properties of mouse RXR{alpha} and PPAR{gamma}1
- Molecular and Cellular Biology, Sunnybrook Research Institute, 2075 Bayview Avenue, T2-058 Toronto, Ont., M4N 2M5 (Canada)
- Molecular and Cellular Biology, Sunnybrook Research Institute, 2075 Bayview Avenue, T2-058 Toronto, Ont. M4N 2M5 (Canada) and Department of Medical Biophysics, University of Toronto, Toronto, Ont. (Canada) and Myelodysplastic Syndrome Program, Department of Medical Oncology, Toronto Sunnybrook Regional Cancer Centre, 2075 Bayview Avenue, T2-058 Toronto, Ont. M4N 2M5 (Canada)
Heterodimerization with RXR is essential for the high-affinity specific binding of multiple nuclear receptors to their cognate DNA sequences. NR dimerization is a two-step process, initiated in solution by interaction between amino acid residues with helices 9 and 10 of the ligand binding domains of RXR and its NR partners. Studies of the orphan nuclear receptor HNF4{alpha}, which forms homodimers exclusively, have indicated that two charged residues in this region, HNF4{alpha}{sub K300} and HNF4{alpha}{sub E327}, are key mediators of dimerization. We have analyzed the contribution of the homologous residues in RXR{alpha} (RXR{alpha}{sub E395}, RXR{alpha}{sub K422}) and PPAR{gamma} (PPAR{gamma}{sub E405}, PPAR{gamma}{sub K432}) to the formation of the RXR{alpha}-PPAR{gamma} heterodimer. Charge reversal mutants of RXR{alpha} (RXR{alpha}{sub E395K}, RXR{alpha}{sub K422E}) and PPAR{gamma} (PPAR{gamma}{sub E405K}, PPAR{gamma}{sub K432E}) show impaired ability to form heterodimers with wild-type PPAR{gamma} and RXR{alpha}, respectively. However, pairs of mutants with balanced charge changes, i.e., RXR{alpha}{sub E395K} with PPAR{gamma}{sub K432E} and RXR{alpha}{sub K422E} with PPAR{gamma}{sub E405K}, are able to form dimers. Ligand response is preserved in the PPAR{gamma} mutants, indicating the mutation does not result in major structural derangement of the protein. These results establish the importance of salt bridges between these residues in the heterodimerization of nuclear receptors, and offer a technical approach to generating functional NR mutants with directed heterodimerization specificity. Such mutants will be valuable tools in the genetic analysis of NR function.
- OSTI ID:
- 20991439
- Journal Information:
- Biochemical and Biophysical Research Communications, Vol. 358, Issue 4; Other Information: DOI: 10.1016/j.bbrc.2007.05.051; PII: S0006-291X(07)00998-9; Copyright (c) 2007 Elsevier Science B.V., Amsterdam, The Netherlands, All rights reserved; Country of input: International Atomic Energy Agency (IAEA); ISSN 0006-291X
- Country of Publication:
- United States
- Language:
- English
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