DNA-binding mechanism of the monomeric orphan nuclear receptor NGFI-B.

The 2.7 A X-ray crystal structure of the DNA-binding domain (DBD) of the orphan nuclear receptor, nerve growth factor-induced-B (NGFI-B), complexed to its high-affinity DNA target, represents the first structure analysis of a nuclear receptor DBD bound as a monomer to DNA. The structure of the core DBD and its interactions with the major groove of the DNA are similar to previously crystallographically solved DBD-DNA complexes in this superfamily; however, residues C-terminal to this core form a separate and unique substructure that interacts extensively and in a sequence-specific way with the minor groove of its DNA target, in particular with the characteristic 3 A-T base-pair identity element that extends 5' to the usual nuclear receptor half-site (AGGTCA).