Determinants of sequence-specific DNA-binding by p48v-myb.

The v-myb oncogene of the avian myeloblastosis virus encodes a nuclear protein, p48v-myb, which binds to DNA in a sequence-specific manner. We have used wild type and mutant forms of this protein expressed in E. coli to study the protein and DNA determinants for sequence-specific DNA-binding. We have shown that only the highly conserved domain at the amino terminus of p48v-myb is required for sequence-specific DNA-binding. However, neither of the tandem 50 amino acid repeats present in this domain is alone sufficient for such binding. We have also demonstrated that p48v-myb can recognize a single consensus myb binding site and appears to interact with DNA as a protein monomer. In addition, we have shown that sequence-specific binding by p48v-myb requires nucleotides which flank the previously reported PyAACT/GG consensus.