A putative Leishmania DNA polymerase theta protects the parasite against oxidative damage

Area of Science:

• Molecular Biology
• Parasitology
• Genetics

Background:

• Leishmania infantum parasites are phagocytized by human macrophages.
• Host macrophages induce DNA damage in parasites using oxidative compounds.
• DNA repair mechanisms in parasites are crucial for survival against host immune responses.

Purpose of the Study:

• To identify and characterize DNA polymerase theta from Leishmania infantum (LiPolθ).
• To investigate the role of LiPolθ in translesion synthesis and DNA damage tolerance.
• To assess the impact of LiPolθ on parasite resistance and infectivity.

Main Methods:

• Identification, purification, and biochemical characterization of LiPolθ.
• Transfection of L. infantum parasites to overexpress LiPolθ.
• Assessing parasite resistance to oxidative and cross-linking agents (hydrogen peroxide, cisplatin, mitomycin C).
• Evaluating the infectivity of LiPolθ-overexpressing parasites toward macrophages.

Main Results:

• LiPolθ was identified as a DNA-dependent DNA polymerase.
• LiPolθ performs translesion synthesis on 8oxoG, abasic sites, and thymine glycol lesions.
• Parasites overexpressing LiPolθ showed increased resistance to DNA damaging agents.
• LiPolθ overexpression enhanced parasite infectivity towards macrophages.

Conclusions:

• LiPolθ is a translesion synthesis polymerase in L. infantum.
• LiPolθ contributes to parasite DNA damage tolerance, enabling resistance to macrophage aggression.
• LiPolθ plays a role in parasite survival and virulence within the host macrophage environment.