Crystal structure of PHO4 bHLH domain-DNA complex: flanking base recognition.
Shimizu, T., Toumoto, A., Ihara, K., Shimizu, M., Kyogoku, Y., Ogawa, N., Oshima, Y., Hakoshima, T.(1997) EMBO J 16: 4689-4697
- PubMed: 9303313
- DOI: https://doi.org/10.1093/emboj/16.15.4689
- Primary Citation of Related Structures:
1A0A - PubMed Abstract:
The crystal structure of a DNA-binding domain of PHO4 complexed with DNA at 2.8 A resolution revealed that the domain folds into a basic-helix-loop-helix (bHLH) motif with a long but compact loop that contains a short alpha-helical segment. This helical structure positions a tryptophan residue into an aromatic cluster so as to make the loop compact. PHO4 binds to DNA as a homodimer with direct reading of both the core E-box sequence CACGTG and its 3'-flanking bases. The 3'-flanking bases GG are recognized by Arg2 and His5. The residues involved in the E-box recognition are His5, Glu9 and Arg13, as already reported for bHLH/Zip proteins MAX and USF, and are different from those recognized by bHLH proteins MyoD and E47, although PHO4 is a bHLH protein.
Organizational Affiliation:
Department of Molecular Biology, Nara Institute of Science and Technology, Ikoma, Japan.