Characterization of the v-myb DNA binding domain.

The transforming protein encoded by the v-myb oncogene is a sequence-specific DNA-binding protein that is thought to be involved in the regulation of gene expression. The N-terminal region of the v-myb protein is composed of two highly conserved tandem repeat sequences of unknown function. It has been speculated that the N-terminal v-myb repeats might be crucial for DNA-binding, since N-terminal deletions destroy the DNA-binding activity of the v-myb protein. Here, we have studied the v-myb DNA-binding domain in more detail. Our results show that the N-terminal region of the v-myb protein is sufficient for specific DNA-binding. Dissection of this region suggests that both repeats are required for DNA-binding, but that both repeats play different roles in v-myb protein DNA interaction. We also show that the myb repeats of a drosophila melanogaster homolog of c-myb function as sequence-specific DNA-binding domain. Our results support the view that specific sequence-recognition, mediated by the conserved myb repeats, is a general feature of myb-related proteins.