PCNA BINDING-PROTEINS IN DROSOPHILA-MELANOGASTER - THE ANALYSIS OF A CONSERVED PCNA BINDING DOMAIN

The eukaryotic polymerase processivity factor, PCNA, interacts with ce ll cycle regulatory proteins such as p21(WAF1/Cip1) and Gadd45 as well as with proteins involved in the mechanics of DNA repair and replicat ion. A conserved PCNA-binding motif is found in a subset of PCNA-inter acting proteins, including p21, suggesting that the regulation of thes e interactions is important for the co-ordination of DNA replication a nd repair. We have identified several classes of protein which bind to Drosophila PCNA. Two of these proteins contain the consensus PCNA-bin ding domain: one is the Dacapo protein, a Drosophila homologue of p21( WAF1/Cip1), and the second is the transposase encoded by the Pogo DNA transposon. A conserved PCNA-binding domain is also present in a human relative of Pogo, named Tigger, suggesting that this domain has a fun ctional role in this class of transposable element. This raises intere sting possibilities fora novel method of transposition in which the tr ansposase might be targeted to replicating DNA. Finally, we have inves tigated the use of this conserved PCNA-binding domain as a predictor o f PCNA-binding capacity.