Structural Studies of the Msx-1 Homeodomain-DNA Complex I

Crystals of the Msx-1 homeodomain-DNA complex have been obtained by hanging-drop vapor diffusion at 293 K in 12% PEG 4000 and 0.1 M sodium acetate pH 4.6. The homeodomain consists of 60 amino acids and is the DNA-binding domain. The DNA in the complex was 16 base pairs with the sequence 5'-TGTCACTAATTGAAGG-3', containing an overhang T at each end. The crystals diffract to 2.15 A (99.8% completeness) using cryogenic (123 K) conditions. The crystals belong to the orthorhombic space group P2(1)2(1)2(1), with unit-cell parameters a = 33.66, b = 60.96, c = 83.37 A. The structure will illuminate the details of Msx-1-DNA binding specificity and clarify its role in transcriptional regulation. Mutations in Msx-1 cause craniofacial deformities in mice.