Recognition and structural perturbation of GC box DNA by Sp1 zinc finger.

Interaction of Sp1 with GC box DNA was investigated by several footprinting experiments. Methylation of four guanine bases is strongly protected by Sp1 binding, while one guanine base in GC box is extremely hypermethylated. Sp1 binding also induces new cleavage at 5'-GA-3' site within GC box by bleomycin-iron complex.