BIOPHYSICAL CHARACTERIZATION OF THE C-MYB DNA-BINDING DOMAIN

We have examined proteins containing the DNA-binding domain of c-Myb w ith biophysical methods. This DNA-binding domain consists of three imp erfect repeats (R1, R2, and R3) conserved among many species, Our resu lts indicate that the DNA-binding domain forms unspecific and specific complexes with oligodeoxynucleotides. In the presence of R1, DNA sequ ences related to a canonical c-Myb-binding site are better discriminat ed. Furthermore, although R2 and R3 are sufficient for sequence-specif ic DNA binding, a structural change of the DNA-binding domain upon spe cific complex formation is induced only when R1 is present. Therefore, R1 might serve as an important element required for secondary structu re alteration upon binding and its stabilization as well as for better discrimination between specific and related DNA sequences.