Mutations in the glucocorticoid receptor DNA-binding domain mimic an allosteric effect of DNA.

Two previously isolated mutations in the glucocorticoid receptor DNA-binding domain (DBD), S459A and P493R, have been postulated to mimic DNA-induced conformational changes in the glucocorticoid receptor DBD, thereby constitutively triggering an allosteric mechanism in which binding of specific DNA normally induces the exposure of otherwise silent glucocorticoid receptor transcriptional activation surfaces. Here we report the three-dimensional structure of the free S459A and P493R mutant DBDs as determined by NMR spectroscopy. The free S459A and P493R structures both display the conformational changes in the DBD dimerization interface that are characteristic of the DNA-bound wild-type DBD, confirming that these mutations mimic an allosteric effect of DNA.

Allosteric effects of DNA on transcriptional regulators.

Selective gene transcription is mediated in part by regulatory proteins that bind to DNA response elements. These regulatory proteins receive global information from signal-transduction events. But transcriptional regulators may also be modified in an allosteric manner by response elements themselves to generate the pattern of regulation that is appropriate to an individual gene.

Influence of a steroid receptor DNA-binding domain on transcriptional regulatory functions.

We have isolated two independent mutations in the DNA-binding domain of the rat glucocorticoid receptor, P493R and S459A, that implicate DNA binding in the control of attached transcriptional activation domains, either that of the receptor itself or of VP16. The mutants are capable of activating transcription normally, but unlike wild-type receptors, they interfere with particular transcriptional activators in yeast and mammalian cells, and inhibit growth when overexpressed in yeast. The mutant residues reside at positions within the three-dimensional structure of the receptor that could, in principle, transduce structural changes from the DNA-binding surface of the receptor to other functional domains.