Effects of linking 15-zinc finger domains on DNA binding specificity and multiple DNA binding modes

To assess the possibility of multi-connection of zinc finger domains for understanding of DNA binding mechanisms and gene regulation, the longest artificial zinc finger protein, Sp1ZF15, has been constructed. This zinc finger consists of 5 units of Sp1 zinc finger peptide connected by canonical short linker sequences (TGEKP). Recognition of the 50 base pairs of DNA and potential binding to shorter targets by Sp1ZF15 were determined. Sequence alterations of the GCG triplet to ATA at a target site clearly showed that Sp1ZF15 changes its DNA binding mode depending on the target sequences. Of special interest is the fact that Sp1ZF15 controls the number of finger domains active in DNA binding corresponding to the length and sequence of the target DNA. These results suggest that artificial transcription factors based upon these multi-zinc finger proteins have great potential for the regulation of a vast number of cellular processes.