A ROLE FOR THE KP LEUCINE-ZIPPER IN REGULATING P-ELEMENT TRANSPOSITION IN DROSOPHILA-MELANOGASTER

The KP element can repress P element mobility in Drosophila melanogast er Three mutant KP elements were made that had either two amino acid s ubstitutions or a single amino acid deletion in the putative leucine z ipper domain found in the KP polypeptide. Each XP element was expresse d from the actin 5C proximal promoter. The wild-type control construct strongly repressed P element mobility, measured by the GD sterility a nd sn(w) mutability assays, in a position-independent manner. The sing le amino acid deletion mutant failed to repress P mobility regardless of its insertion site, while repression of P element mobility by tile double amino acid substitution mutants was position dependent. The res ults show that the leucine zipper of the KP polypeptide is important f or P element regulation. This supports the multimer-poisoning model of P element repression, because leucine zipper motifs are involved in p rotein-protein interactions.