DNA Repair (Amst). 2011 Feb 23. [Epub ahead of print]
Base excision repair apurinic/apyrimidinic endonucleases in apicomplexan parasite Toxoplasma gondii
Onyango DO, Naguleswaran A, Delaplane S, Reed A, Kelley MR, Georgiadis MM, Sullivan WJ Jr.
Department of Pharmacology and Toxicology, Indiana University School of Medicine, Indianapolis, IN 46202, United States.
DNA repair is essential for cell viability and proliferation. In addition to reactive oxygen produced as a byproduct of their own metabolism, intracellular parasites also have to manage oxidative stress generated as a defense mechanism by the host. The spontaneous loss of DNA bases due to hydrolysis and oxidative DNA damage in intracellular parasites is great, but little is known about the type of DNA repair machineries that exist in these early-branching eukaryotes. However, it is clear, processes similar to DNA base excision repair (BER) must exist to rectify spontaneous and host-mediated damage in Toxoplasma gondii. Here we report that T. gondii, an opportunistic protozoan pathogen, possesses two apurinic/apyrimidinic (AP) endonucleases that function in DNA BER. We characterize the enzymatic activities of Toxoplasma exonuclease III (ExoIII, or Ape1) and endonuclease IV (EndoIV, or Apn1), designated TgAPE and TgAPN, respectively. Over-expression of TgAPN in Toxoplasma conferred protection from DNA damage, and viable knockouts of TgAPN were not obtainable. We generated an inducible TgAPN knockdown mutant using a ligand-controlled destabilization domain to establish that TgAPN is critical for Toxoplasma to recover from DNA damage. The importance of TgAPN and the fact that humans lack any observable APN family activity highlights TgAPN as a promising candidate for drug development to treat toxoplasmosis.
Copyright © 2011 Elsevier B.V. All rights reserved.
PMID: 21353648 [PubMed - as supplied by publisher]