The effect of cysteine substitution on the DNA binding affinity of the Estrogen Receptor-Beta (ER-_) DNA Binding Domain

Abstract

By Tsitsi Nyamajenjere, Biochemistry

Advisor: Pearl Tsang

Presentation ID: AM_D18

Abstract: The estrogen receptor (ER) belongs to a family of receptors known as nuclear receptors that function as ligand-activated transcription factors. The ER has 3 domains; N-terminal domain (NTD) which is involved in regulation of transcription, a DNA binding domain (DBD), and a C-terminal hormone binding domain (HBD) which binds to estrogen and induces a conformational change which causes the DNA binding domain to bind as a homodimer to DNA palindromic sequences known as estrogen response elements (ERE). The DBD has two zinc finger motifs which facilitate DNA binding. There are two forms of estrogen receptors; ER-_ and ER-_. The DNA binding domain of the ER-_ has been extensively studied but little is known about the ER-_ DBD in terms of its DNA binding and structure. Due to this, a mutated form of the ER-_ DBD was prepared (for optimal protein solubility) for future structural NMR study. To verify that this mutant binds to DNA, we focused upon characterization of the binding affinity of this mutated ER-_ DBD, to the ERE DNA consensus sequence. Here, we report on the establishment of an Electrophoretic Mobility Shift Assay (EMSA) method to determine the binding of our variant ER-_ DBD to ERE using EMSA.