Crystal structure of the DNA binding domain of the heat shock transcription factor.
Harrison, C.J., Bohm, A.A., Nelson, H.C.(1994) Science 263: 224-227
- PubMed: 8284672 
- DOI: https://doi.org/10.1126/science.8284672
- Primary Citation of Related Structures:  
2HTS - PubMed Abstract: 
The structure of the DNA binding domain, determined at 1.8 angstrom resolution, contains a three-helix bundle that is capped by a four-stranded antiparallel beta sheet. This structure is a variant of the helix-turn-helix motif, typified by catabolite activator protein. In the heat shock transcription factor, the first helix of the motif (alpha 2) has an alpha-helical bulge and a proline-induced kink. The angle between the two helices of the motif (alpha 2 and alpha 3) is about 20 degrees smaller than the average for canonical helix-turn-helix proteins. Nevertheless, the relative positions of the first and third helices of the bundle (alpha 1 and alpha 3) are conserved. It is proposed here that the first helix of the three-helix bundle be considered a component of the helix-turn-helix motif.
Organizational Affiliation: 
Department of Molecular and Cell Biology, University of California, Berkeley 94720.