END EFFECTS IN DNA RECOGNITION BY ZINC-FINGER ARRAYS

The paradigmatic DNA binding domain from the transcription factor Zif2 68 contains three zinc finger modules in tandem repeat. When bound to their cognate DNA site the fingers read out the sequence of one DMA st rand by making a linear series of successive base contacts, It is show n that the base-specific protein-DNA contacts made from the ends of th e Zif268 three-finger array contribute less to the stability of the in termolecular complex than do structurally equivalent contacts from mor e central regions of the DNA binding domain, The effect is akin to the end fraying observed in duplex nucleic acid molecules.