Characterization of the DNA-binding properties of the receptor for 2,3,7,8-tetrachlorodibenzo-p-dioxin

Abstract

The DNA-binding properties of the receptor for 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) were investigated using chromatography on DNA-cellulose columns. A maximal binding of about 40% of the total receptor complex to DNA-cellulose was observed. In order to interact with DNA, the receptor must first bind TCDD. A heat-activation step followed by gel permeation chromatography using Sephadex G-25 increased the binding of the cytosolic receptor to DNA. The DNA-binding ability of the receptor was almost lost following mild proteolysis using trypsin or α-chymotrypsin, although these treatments did not reduce its ligand binding capacity and had no apparent effect on its size. Furthermore, pre-treatment of the DNA-cellulose column with an intercalating drug, ethidium bromide, resulted in inhibition of the binding of the TCDd-receptor complex to DNA, indicating that not only electrostatic interactions but also the configuration of DNA are of importance in receptor-DNA interactions.