Genetic analysis of the drosophila DNAprim gene: The function of the 60-kDprimase subunit of DNA polymerase opposes the fat facets signaling pathwayin the developing eye

The Drosophila DNAprim gene encodes the large subunit (60 kD) of DNA primas e, the part of DNA polymerase alpha that synthesizes RNA primers during DNA replication. The precise function of the 60-kD subunit is unknown. In a mu tagenesis screen for suppressors of the fat facets (faf) mutant eye phenoty pe, rye identified mutations in DNAprim. The faf gene encodes a deubiquitin ating enzyme required specifically for patterning the compound eye. The DNA sequences of four DNAprim alleles were determined and these define essenti al protein domains. We show that while flies lacking DNAprim activity are l ethal, flies with reduced DNAprim activity display morphological defects in their eyes, and unlike faf mutants, cell cycle abnormalities in larval eye discs. Mechanisms by which DNA primase levels might influence the faf-depe ndent cell communication pathway are discussed.