A ROLE IN DNA-BINDING FOR THE LINKER SEQUENCES OF THE 1ST 3 ZINC FINGERS OF TFIIIA

Zinc fingers of the TFIIIA type are connected by short linker sequence s between the structural units. Structural investigations by 2D NMR in solution and by X-ray crystallographic analyses of complexes with DNA point to a passive role for the linkers. We have therefore investigat ed the influence of the linker sequence on DNA binding using as a mode l the first three fingers of the protein TFIIIA. Insertion of certain heterologous linkers abolishes binding, and replacement of individual amino acids can reduce binding by tactors of up to twenty-tour.