Unravelling the role of SNM1 in the DNA repair system of Trypanosoma brucei

James A. Sullivan, Jie Lun Tong, Martin Wong, Ambika Kumar, Hajrah Sarkar, Sarah Ali, Ikran Hussein, Iqra Zaman, Emma Louise Meredith, Nuala A. Helsby, Longqin Hu, Shane R. Wilkinson

Research output: Contribution to journalArticlepeer-review

6 Scopus citations


All living cells are subject to agents that promote DNA damage. A particularly lethal lesion are interstrand cross-links (ICL), a property exploited by several anti-cancer chemotherapies. In yeast and humans, an enzyme that plays a key role in repairing such damage are the PSO2/SNM1 nucleases. Here, we report that Trypanosoma brucei, the causative agent of African trypanosomiasis, possesses a bona fide member of this family (called TbSNM1) with expression of the parasite enzyme able to suppress the sensitivity yeast pso2Δ mutants display towards mechlorethamine, an ICL-inducing compound. By disrupting the Tbsnm1 gene, we demonstrate that TbSNM1 activity is non-essential to the medically relevant T.brucei life cycle stage. However, trypanosomes lacking this enzyme are more susceptible to bi- and tri-functional DNA alkylating agents with this phenotype readily complemented by ectopic expression of Tbsnm1. Genetically modified variants of the null mutant line were subsequently used to establish the anti-parasitic mechanism of action of nitrobenzylphosphoramide mustard and aziridinyl nitrobenzamide prodrugs, compounds previously shown to possess potent trypanocidal properties while exhibiting limited toxicity to mammalian cells. This established that these agents, following activation by a parasite specific type I nitroreductase, produce metabolites that promote formation of ICLs leading to inhibition of trypanosomal growth. Trypanosomiasis is of medical and veterinary importance across sub-Saharan Africa. Trypanosoma brucei, the causative agent of these infections, expresses a DNA repair enzyme that exhibits characteristics typical of PSO2/SNM1 family of nucleases. This activity although non-essential for the growth of bloodstream form parasites does play a key role in fixing the damage caused by DNA interstrand crosslinking agents.

Original languageAmerican English
Pages (from-to)827-838
Number of pages12
JournalMolecular Microbiology
Issue number4
StatePublished - May 1 2015

ASJC Scopus subject areas

  • Microbiology
  • Molecular Biology


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