SNAP annotations: PDB entry 1apl

PDB-id

1apl; DSSR-derived features in text and JSON formats; DNAproDB

Class

DNA binding protein-DNA

Method

X-ray (2.7 Å)

Summary

Crystal structure of a mat-alpha2 homeodomain-operator complex suggests a general model for homeodomain-DNA interactions

Reference

Wolberger C, Vershon AK, Liu B, Johnson AD, Pabo CO (1991): "Crystal structure of a MAT alpha 2 homeodomain-operator complex suggests a general model for homeodomain-DNA interactions." Cell(Cambridge,Mass.), 67, 517-528. doi: 10.1016/0092-8674(91)90526-5.

Abstract

The MAT alpha 2 homeodomain regulates the expression of cell type-specific genes in yeast. We have determined the 2.7 A resolution crystal structure of the alpha 2 homeodomain bound to a biologically relevant DNA sequence. The DNA in this complex is contacted primarily by the third of three alpha-helices, with additional contacts coming from an N-terminal arm. Comparison of the yeast alpha 2 and the Drosophila engrailed homeodomain-DNA complexes shows that the protein fold is highly conserved, despite a 3-residue insertion in alpha 2 and only 27% sequence identity between the two homeodomains. Moreover, the orientation of the recognition helix on the DNA is also conserved. This docking arrangement is maintained by side chain contacts with the DNA--primarily the sugar-phosphate backbone--that are identical in alpha 2 and engrailed. Since these residues are conserved among all homeodomains, we propose that the contacts with the DNA are also conserved and suggest a general model for homeodomain-DNA interactions.