Estrogen receptors alpha and beta exhibit different estradiol and estrogen response element binding in the presence of nonspecific DNA.

Estrogen receptors (ER) alpha and beta bind estradiol (E(2)) 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 E(2)--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 E(2)--ER alpha association, both ERE-containing and plasmid DNA decreased the rate of E(2) association with ER beta. Poly(dI-dC) decreased ERE--SBC of ER alpha, but did not affect the ERE--SBC of ER beta. Salmon sperm genomic DNA decreased the ERE--SBC of ER alpha, but increased the ERE--SBC of ER beta. 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 ER alpha and ER beta. Copyright 2001 Academic Press.