Alteration of DNA binding specificity by nickel (II) substitution in three zinc (II) fingers of transcription factor Sp1.

Transcription factor Sp1, which has a DNA binding domain composed of three zinc fingers, binds to GC box (consensus sequence, G/T-GGGCGG-G/A-G/A-C/T) and activates the transcription by RNA polymerase II. Metal substitution of nickel(II) for zinc(II) in Sp1 causes no differences in the mode of protein-DNA interaction. However, sequence preference of Ni(II)Sp1 changes from 5'-GGGGCGGGGC to 5'-GGGGCGTGGC, and is distinct from that of Zn(II)Sp1. The result indicates an important effect of metal-induced folding on sequence-specific recognition of DNA by zinc-finger proteins.