Surface plasmon resonance study of cooperative interactions of estrogen receptor α and specificity protein 1 with composite DNA elements

Abstract

Estrogen receptor a (ERα) and Specificity protein 1 (Spl) are transcription factors (TF) that are involved in regulating progesterone receptor (PR) gene expression through cooperative interactions with DNA. The natural composite DNA +571 ERE/Sp1 site in promoter A of the progesterone receptor contains a half-site of estrogen response elements (1/2ERE) upstream of two Spl binding sites (the proximal Spl (Spl/P) and distal Spl (Spl/D)) with a 4 bp spacer. Here, we have developed a protocol for studying the cooperative interaction of Spl and ERa with the composite DNA of +57l ERE/Spl site using Biacore T200, a high sensitivity surface plasmon resonance spectroscopy. With this protocol, we have concluded that Spl binding enhances the overall ERa binding to the composite DNA. We have also determined the optimal spacer distance between the 1/2ERE and Spl/D for the best cooperative protein binding. This study is pivotal in guiding the bioinformatics simulation to yield an exact model of the spacer dependency of the transcription factor/cofactor-DNA interactions, which is important for understanding the nuclear receptor regulating activity through other coactivators.