DNA Bending by Steroid Receptors

72 p.Thesis (Ph.D.)--University of Illinois at Urbana-Champaign, 1997.Protein induced DNA bending is a common feature of many prokaryotic and eukaryotic DNA binding proteins and may be important in the regulation of gene transcription. Therefore, it was of interest to more clearly examine receptor-induced DNA bending and its relationship to transcriptional activation. We have used circular permutation analysis to determine the degree of DNA bending induced by binding of the GR DNA binding domain (DBD), the human PR DBD, PR-A:A and PR-B:B homodimers, and PR-A:B heterodimers to the HRE. We find that PR-A:A, PR-B:B and PR-A:B all induce approximately the same degree of DNA bending and that the GR and PR DBDs induced DNA bending on binding to the HRE We also determined whether binding of ligand influenced the magnitude of ER induced DNA bending using phasing analysis. We find that unoccupied wild type (WT) ER induced a larger directed DNA bend upon binding the HRE than the estrogen occupied ER. Constitutively active mutant receptors had directed DNA bending angles similar to estrogen occupied WT ER. These findings imply that transcriptionally active mutant ERs induce directed bending angles that are similar to the DNA bend induced by WT ER.U of I OnlyRestricted to the U of I community idenfinitely during batch ingest of legacy ETD