title: Trypanosoma brucei AP endonuclease 1 has a major role in the repair of abasic sites and protection against DNA-damaging agents.
abstract: DNA repair mechanisms guarantee the maintenance of genome integrity, which is critical for cell viability and proliferation in all organisms. As part of the cellular defenses to DNA damage, apurinic/apyrimidinic (AP) endonucleases repair the abasic sites produced by spontaneous hydrolysis, oxidative or alkylation base damage and during base excision repair (BER). Trypanosoma brucei, the protozoan pathogen responsible of human sleeping sickness, has a class II AP endonuclease (TBAPE1) with a high degree of homology to human APE1 and bacterial exonuclease III. The purified recombinant enzyme cleaves AP sites and removes 3'-phosphoglycolate groups from 3'-ends. To study its cellular function, we have established TBAPE1-deficient cell lines derived from bloodstream stage trypanosomes, thus confirming that the AP endonuclease is not essential for viability in this cell type under in vitro culture conditions. The role of TBAPE1 in the removal of AP sites is supported by the inverse correlation between the level of AP endonuclease in the cell and the number of endogenously generated abasic sites in its genomic DNA. Furthermore, depletion of TBAPE1 renders cells hypersensitive to AP site and strand break-inducing agents such as methotrexate and phleomycin respectively but not to alkylating agents. Finally, the increased susceptibility that TBAPE1-depleted cells show to nitric oxide suggests an essential role for this DNA repair enzyme in protection against the immune defenses of the mammalian host.
authors: Instituto de Parasitología y Biomedicina López-Neyra, Consejo Superior de Investigaciones Científicas (CSIC), Armilla, Granada, Spain.
authors: Karen S
authors: KS
authors: Charret
authors: Cristina E
authors: CE
authors: Requena
authors: Víctor M
authors: VM
authors: Castillo-Acosta
authors: Luis M
authors: LM
authors: Ruiz-Pérez
authors: Dolores
authors: D
authors: González-Pacanowska
authors: Antonio E
authors: AE
authors: Vidal
mesh_terms: D000478:Alkylation / Q000187:drug effects; D000818:Animals; D001483:Base Sequence; D002457:Cell Extracts; D049109:Cell Proliferation / Q000187:drug effects; D019610:Cytoprotection / Q000187:drug effects*; D004249:DNA Damage; D004260:DNA Repair / Q000187:drug effects*; D043603:DNA-(Apurinic or Apyrimidinic Site) Lyase / Q000378:metabolism*; D004789:Enzyme Activation / Q000187:drug effects; D016678:Genome / Q000235:genetics; D006898:Hydroxylamines / Q000633:toxicity; D042541:Intracellular Space / Q000187:drug effects / Q000378:metabolism; D008018:Life Cycle Stages / Q000187:drug effects; D008727:Methotrexate / Q000633:toxicity; D008969:Molecular Sequence Data; D009153:Mutagens / Q000633:toxicity*; D009569:Nitric Oxide / Q000378:metabolism; D021381:Protein Transport / Q000187:drug effects; D014346:Trypanosoma brucei brucei / Q000166:cytology / Q000201:enzymology* / Q000254:growth & development
chemical_list: D002457:Cell Extracts; D006898:Hydroxylamines; D009153:Mutagens; D009569:Nitric Oxide; C005214:methoxyamine; D043603:DNA-(Apurinic or Apyrimidinic Site) Lyase; D008727:Methotrexate