Specific DNA Binding by c-Myb: Evidence for a Double Helix-Turn-Helix- Related Motif

• Published in: Science (American Association for the Advancement of Science) 1991-09, Vol.253 (5024), p.1140-1143
• Main Authors: Gabrielsen, Odd S., Sentenac, André, Fromageot, Pierre
• Format: Article
• Language: English
• Subjects: Amino Acid Sequence; Amino acids; Animals; Base Sequence; Binding Sites; Chemical bases; Chickens; Deoxyribonucleic acid; DNA; DNA - metabolism; DNA binding proteins; DNA probes; DNA-Binding Proteins - metabolism; Electrophoresis; Gels; Genetic transcription; Genetics; Half lives; Molecular Sequence Data; Mutagenesis; Mutagenesis, Site-Directed; Myeloid cells; Oligonucleotide Probes; Oligonucleotides; Oncogenes; Polymerase Chain Reaction; Protein Conformation; Proteins; Proto-Oncogene Proteins - genetics; Proto-Oncogene Proteins - metabolism; Proto-Oncogene Proteins c-myb; Recombinant Proteins - metabolism; Restriction Mapping; Sequence Homology, Nucleic Acid; Transcription (Genetics); Transcription Factors - metabolism
• ISSN: 0036-8075; 1095-9203
• DOI: 10.1126/science.1887237

The c-Myb protein is a sequence-specific DNA binding protein that activates transcription in hematopoietic cells. Three imperfect repeats (R$_1$, R$_2$, and R$_3$) that contain regularly spaced tryptophan residues form the DNA binding domain of c-Myb. A fragment of c-Myb that contained the R$_2$ and R$_3$ regions bound specifically to a DNA sequence recognized by c-Myb plus ten additional base pairs at the 3′ end of the element. The R$_2$R$_3$ fragment was predicted to contain two consecutive helix-turn-helix (HTH) motifs with unconventional turns. Mutagenesis of amino acids in R$_2$R$_3$ at positions that correspond to DNA-contacting amino acids in other HTH-containing proteins abolished specific DNA binding without affecting nonspecific DNA interactions.