Title dUTPase expression correlates with cell division potential in Drosophila melanogaster Authors’ names

dUTPase is a dNTP sanitizing enzyme that prevents the appearance of the potentially harmful uracil bases in DNA by hydrolyzing cellular dUTP. This function of dUTPase is found to be essential in many organisms including Drosophila melanogaster. Previously we showed that the expression pattern of dUTPase determines the extent of uracil accumulation in the genome of different tissues. We wished to reveal the regulatory mechanism that eventually leaves a set of tissues to have uracil-free and intact genome. We found that the expression pattern established by the promoter of Drosophila dUTPase overlaps with mRNA and protein expression pattern, excluding the involvement of other posttranscriptional contribution. This promoter was found to be active in primordial tissues, such as in imaginal discs of the larvae, in the larval brain and in reproductive organs. In the case of brain and imaginal tissues, we observed that the promoter activity depends on DRE motifs, the docking site of DREF, which is known as a transcriptional activator of genes involved in replication and proliferation. These results suggest that dUTPase expression is fine-tuned to meet the requirements of DNA synthesis, in tissues where the maintenance of genome integrity is of high importance. Introduction Effective and accurate cellular DNA synthesis requires a well regulated deoxynucleotide triphosphate (dNTP) pool. Both the concentration and the ratio of dNTP components affect replication fidelity and robustness. Abnormalities in the dNTP pool can bias DNA synthesis, resulting in DNA damage or replication arrest [1,2]. Physiological dNTP pool consisting of modified nucleotides can also result in lesions in DNA after incorporation. Most common modified dNTPs can be 8-oxo-deoxyguanosine triphosphate (8-OH-dGTP), formed upon oxidation, deoxyinositol triphosphate (dITP) and deoxyuridine triphosphate (dUTP), formed upon deamination. Enzymatic machineries have been evolved to get rid of such modified moieties sanitizing the dNTP pool. MTH1 and MTH2, homologues of the Escherichia coli MutT, selectively hydrolyse 8-OH-dGTP [3,4]; dITPase, the homologue of the E. coli RdgB eliminates dITP [5]. dUTPase selectively hydrolyzes dUTP thereby eliminating it from the dNTP pool [6–11]. In addition, it contributes to thymidylate biosynthesis since its hydrolysis product; deoxyuridine monophosphate (dUMP) is the precursor of deoxythymidylate monophosphate (dTMP) [12]. dUTP elimination was found to be essential in several organisms such as E. coli, Saccharomyces cerevisiae, Trypanosoma brucei, Arabidopsis thaliana, Caenorhabditis elegans and Drosophila melanogaster [13–18]. In most cases, lethal consequences of Page 2 of 34 FEBS Journal