National Center for
3VRW: Vdr Ligand Binding Domain In Complex With 22s-Butyl-2-Methylidene-26, 27-Dimethyl-19,24-Dinor-1alpha,25-Dihydroxyvitamin D3
Butyl pocket formation in the vitamin d receptor strongly affects the agonistic or antagonistic behavior of ligands
J. Med. Chem. (2012) 55 p.4373-4381
Previously, we reported that 22S-butyl-25,26,27-trinor-1alpha,24-dihydroxyvitamin D(3)2 represents a new class of antagonist for the vitamin D receptor (VDR). The crystal structure of the ligand-binding domain (LBD) of VDR complexed with 2 showed the formation of a butyl pocket to accommodate the 22-butyl group and insufficient interactions between ligand 2 and the C-terminus of VDR. Here, we designed and synthesized new analogues 5a-c and evaluated their biological activities to probe whether agonistic activity is recovered when the analogue restores interactions with the C-terminus of VDR. Analogues 5a-c exhibited full agonistic activity in transactivation. Interestingly, 5c, which bears a 24-diethyl group, completely recovered agonistic activity, although 3c and 4c act as an antagonist and a weak agonist, respectively. The crystal structures of VDR-LBD complexed with 3a, 4a, 5a, and 5c were solved, and the results confirmed that butyl pocket formation in VDR strongly affects the agonistic or antagonistic behaviors of ligands.