Estrogen Receptors α and β Exhibit Different Estradiol and Estrogen Response Element Binding in the Presence of Nonspecific DNA

Estrogen receptors (ER) α and β bind estradiol (E2) and estrogen response element (ERE) DNA sequences with high affinities. The different migration of ER–ERE complexes in the presence or absence of nonspecific DNA suggests that DNA may affect ER conformation and function. We measured the rate of E2–ER association and specific ER–ERE binding capacity (ERE-SBC) in the presence or absence of nonspecific DNA. Whereas DNA did not alter the rate of E2–ERα association, both ERE-containing and plasmid DNA decreased the rate of E2 association with ERβ. Poly(dI-dC) decreased ERE-SBC of ERα, but did not affect the ERE-SBC of ERβ. Salmon sperm genomic DNA decreased the ERE-SBC of ERα, but increased the ERE-SBC of ERβ. We speculate that interaction of ER with genomic DNA may contribute to ER activation and play a role in the observed differences in transcriptional activity of ERα and ERβ.