Molecular cloning and expression during development of the Drosophila genefor the catalytic subunit of DNA polymerase epsilon

We have cloned the genomic DNA and cDNA of Drosophila DNA polymerase epsilo n (pol-epsilon) catalytic subunit (GenBank No. AB035512). The gene is separ ated into four exons by three short introns, and the open reading frame con sists of 6660 base pairs (bp) capable of encoding a polypeptide of 2220 ami no acid residues. The calculated molecular mass is 255 018, similar to that of mammalian and yeast homologues. The deduced amino acid sequence of the pol-epsilon catalytic subunit shares approximately 41% identity with human and mouse homologues as well as significant homology those of C. elegans, S . cerevisiae and S. pombe. Similar to the pol-epsilon catalytic subunits fr om other species, the pol-epsilon catalytic subunit contains domains for DN A polymerization and 3'-5' exonuclease in the N-terminal region, and two po tential zinc-finger domains in the C-terminal regions. Interestingly, a 38 amino acid sequence in the C-terminal region from amino acid positions 1823 to 1861 is similar to the site for Mycoplasma ATP binding and/or ATPase do main (GenBank No. P47365). Northern hybridization analysis indicated that t he gene is expressed at the highest levels in unfertilized eggs, followed b y zero to 4 h embryos and adult females, and then embryos at other embryoni c stages, instar larva stages and adult males. Low levels of the mRNA were also detected at the pupa stage. This pattern of expression is similar to t hose of DNA replication-related enzymes such as DNA polymerase alpha and be ta except for the high level of expression in adult males. (C) 2000 Elsevie r Science B.V. All rights reserved.