Functional genetic evaluation of DNA house-cleaning enzymes in the malaria parasite: dUTPase and Ap4AH are essential in Plasmodium berghei but ITPase and NDH are dispensable

ABSTRACT

Background: Cellular metabolism generates reactive oxygen species. The oxidation and deamination of the deoxynucleoside triphosphate (dNTP) pool results in the formation of non-canonical, toxic dNTPs that can cause mutations, genome instability, and cell death. House-cleaning or sanitation enzymes that break down and detoxify non-canonical nucleotides play major protective roles in nucleotide metabolism and constitute key drug targets for cancer and various pathogens. We hypothesized that owing to their protective roles in nucleotide metabolism, these house-cleaning enzymes are key drug targets in the malaria parasite.

Methods: Using the rodent malaria parasite Plasmodium berghei we evaluate here, by gene targeting, a group of conserved proteins with a putative function in the detoxification of non-canonical nucleotides as potential antimalarial drug targets: they are inosine triphosphate pyrophosphatase (ITPase), deoxyuridine triphosphate pyrophosphatase (dUTPase) and two NuDiX hydroxylases, the diadenosine tetraphosphate (Ap4A) hydrolase and the nucleoside triphosphate hydrolase (NDH).

Results: While all four proteins are expressed constitutively across the intraerythrocytic developmental cycle, neither ITPase nor NDH are required for parasite viability. dutpase and ap4ah null mutants, on the other hand, are not viable suggesting an essential function for these proteins for the malaria parasite.

Conclusions: Plasmodium dUTPase and Ap4A could be drug targets in the malaria parasite.

KEYWORDS:

• Malaria
• house-cleaning enzymes
• drug targets
• dUTPase
• ITPase
• NuDiX
• nucleoside triphosphate pyrophosphohydrolase

Authors’ contributions

HK: Conceptualization, Formal analysis, Investigation, Supervision, Methodology, Visualization, Writing – original draft, Writing – review & editing

JK: Formal analysis, Investigation, Supervision, Methodology, Visualization, Writing – review & editing;

MS: Investigation, Supervision, Visualization, Writing – review & editing

MR: Methodology, Resources, Visualization, Writing – review & editing

JMS: Methodology, Resources, Visualization, Writing – review & editing

GM: Conceptualization, Project administration, Formal analysis, Resources, Investigation, Supervision, Methodology, Writing – original draft, Writing – review & editing

FF: Funding acquisition, Project administration, Resources, Supervision, Writing – original draft, Writing – review & editing.

Declaration of interest

F Frischknecht was a member of the EU FP7 Network of Excellence EVIMalaR. The authors have no other relevant affiliations or financial involvement with any organization or entity with a financial interest in or financial conflict with the subject matter or materials discussed in the manuscript. This includes employment, consultancies, honoraria, stock ownership or options, expert testimony, grants or patents received or pending, or royalties.

Reviewer disclosures

Peer reviewers on this manuscript have no relevant financial or other relationships to disclose.

Supplementary material

Supplemental data for this article can be accessed here.

Additional information

Funding

This work was supported by a fellowship from the Deutsche Akademischer Austauschdienst (DAAD; awarded to H Kumar) and grants from the Chica and Heinz Schaller Foundation, the European Research Council (StG 281719), the Deutsche Forschungsgemeinschaft (SFB 1129) and the Heidelberg University cluster of excellence CellNetworks (awarded to F Frischknecht). JM Santos was supported by the Portuguese Fundação para a Ciência e a Tecnologia (SFRH/BD/63849/2009).