Mutations in the “zinc fingers” or in the n-terminal region of the DNA binding domain of the human glucocorticosteroid receptor facilitate its salt-induced transformation, but do not modify hormone binding

While the effects of the ligand (hormone)_binding domain (LBD) on other receptor domain functions are kwown, the effects of other domains on LBD functions have not been studied. In this work, we examined the importance of the strutural integrity of other domains of the human glucocorticosteroid receptor (hGR) on LBD activity (stability of 8S complexes, binding of hormone, and transformation from the 8S to the 4S form). Several mutations introduced outside the LBD affect neither the formation of stable 8S heterooligomeric complexes nor the hGR binding affinity for the agonist triacinolone acetonide (TA) or the 8S-hGR into a 4S form. Deletion of the second zinc finger of the DNA binding domain (DBD) facilitated 8S dissociation whether the ligand was TA or RU486. Deletion of the first zinc finger facilitated dissociation only in the presence of RU486. Deletion of the first zinc finger facilitated dissociation only in the presence of RU486. while replacement of PRO 416 (in the N-terminal region of the DBD) by ARG destabilized the 8S form only in the presence of TA. Variations in the salt-sensitivity of the mutated 8S GR complexes as a function of the ligand suggest that the DBD may interact functioanlly (if not physically) with the LBD. This interaction (possibly mediated by hsp90) could be influenced by minor structural differences between agonist and antagonist-GR complexes.