Enzyme kinetics of deoxyuridine triphosphatase from Western corn rootworm

The Western corn rootworm (WCR), Diabrotica virgifera virgifera, is a highly adaptable insect pest that has evolved resistance to a variety of control strategies, including insecticides. Therefore, it is interesting to examine how housekeeping proteins in WCR have been changed under WCR-controlling strategies. In this study, we focused on one of such proteins in WCR, a ubiquitous enzyme 5'-triphosphate nucleotidohydrolase (dUTPase). In the thymidine synthetic pathway, dUTPase hydrolyzes deoxyuridine triphosphate (dUTP) and supplies the substrate, deoxyuridine monophosphate, for the thymidylate synthase (TS). It decreases the cellular content of uracil, reducing uracil misincorporation into DNA. Suppressing the dUTPase activity, therefore, contributes to thymineless death. In this study, we investigated the enzymatic properties of dUTPase.

The WCR dUTPase gene (DUT) was synthesized with the addition of His-tag corresponding DNA sequence and then cloned and expressed in Escherichia coli, and the protein product was purified. The product of WCR DUT hydrolyzed dUTP and was designated as dUTPase. WCR dUTPase did not hydrolyze dATP, dTTP, dCTP, or dGTP. WCR dUTPase was analyzed via size-exclusion chromatography and exhibited a molecular weight corresponding to that of trimer. The present format can be interpreted as nuclear trimer type. Possible isomers will be examined once transcriptome analyses are conducted.