SOLUTION STRUCTURE OF THE KLUYVEROMYCES-LACTIS LAC9 CD(2)CYS(6) DNA-BINDING DOMAIN

The Zn(2)Cys(6) DNA-binding domain has been identified by sequence hom ology in approximately forty fungal proteins, including the K. lactis LAC9 transcriptional activator Using H-1 NMR spectroscopy, we have det ermined the solution structure of a cadmium-substituted form of the LA C9 DNA-binding domain. We have complemented this approach by applying a series of Cd-113-H-1 NMR experiments, including several novel hetero TOCSY-based techniques. The DNA-binding domain forms a core of two alp ha-helix/extended strand segments around the Cd-2 binuclear cluster wi th a network of amide proton-cysteinyl S gamma hydrogen bonds stablizi ng the cluster. Comparison with other Zn(2)Cys6 domain structures prov ides insight into the common structural elements used in metal coordin ation and DNA binding.