title: Unravelling the role of SNM1 in the DNA repair system of Trypanosoma brucei.
abstract: 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.
authors.affiliation: School of Biological & Chemical Sciences, Queen Mary University of London, Mile End Road, London, E1 4NS, UK.
authors.forename: James A
authors.initials: JA
authors.lastname: Sullivan
authors.affiliation: School of Biological & Chemical Sciences, Queen Mary University of London, Mile End Road, London, E1 4NS, UK.
authors.forename: Jie Lun
authors.initials: JL
authors.lastname: Tong
authors.affiliation: School of Biological & Chemical Sciences, Queen Mary University of London, Mile End Road, London, E1 4NS, UK.
authors.forename: Martin
authors.initials: M
authors.lastname: Wong
authors.affiliation: School of Biological & Chemical Sciences, Queen Mary University of London, Mile End Road, London, E1 4NS, UK.
authors.forename: Ambika
authors.initials: A
authors.lastname: Kumar
authors.affiliation: School of Biological & Chemical Sciences, Queen Mary University of London, Mile End Road, London, E1 4NS, UK.
authors.forename: Hajrah
authors.initials: H
authors.lastname: Sarkar
authors.affiliation: School of Biological & Chemical Sciences, Queen Mary University of London, Mile End Road, London, E1 4NS, UK.
authors.forename: Sarah
authors.initials: S
authors.lastname: Ali
authors.affiliation: School of Biological & Chemical Sciences, Queen Mary University of London, Mile End Road, London, E1 4NS, UK.
authors.forename: Ikran
authors.initials: I
authors.lastname: Hussein
authors.affiliation: School of Biological & Chemical Sciences, Queen Mary University of London, Mile End Road, London, E1 4NS, UK.
authors.forename: Iqra
authors.initials: I
authors.lastname: Zaman
authors.affiliation: School of Biological & Chemical Sciences, Queen Mary University of London, Mile End Road, London, E1 4NS, UK.
authors.forename: Emma Louise
authors.initials: EL
authors.lastname: Meredith
authors.affiliation: Department of Molecular Medicine and Pathology, University of Auckland, Private Bag 92019, Auckland, New Zealand.
authors.forename: Nuala A
authors.initials: NA
authors.lastname: Helsby
authors.affiliation: Department of Medicinal Chemistry, Ernest Mario School of Pharmacy, Rutgers, The State University of New Jersey, Piscataway, NJ, 08854, USA.
authors.forename: Longqin
authors.initials: L
authors.lastname: Hu
authors.affiliation: School of Biological & Chemical Sciences, Queen Mary University of London, Mile End Road, London, E1 4NS, UK.
authors.forename: Shane R
authors.initials: SR
authors.lastname: Wilkinson
mesh_terms: D001388:Aziridines / Q000494:pharmacology; D004249:DNA Damage; D004260:DNA Repair / Q000187:drug effects; D005816:Genetic Complementation Test; D018503:Genome, Protozoan; D008466:Mechlorethamine / Q000494:pharmacology; D009154:Mutation; D009601:Nitroreductases / Q000378:metabolism; D010641:Phenotype; D012441:Saccharomyces cerevisiae / Q000235:genetics; D017421:Sequence Analysis; D014344:Trypanocidal Agents / Q000494:pharmacology; D014346:Trypanosoma brucei brucei / Q000187:drug effects / Q000201:enzymology* / Q000235:genetics* / Q000254:growth & development
chemical_list: D001388:Aziridines; D014344:Trypanocidal Agents; D008466:Mechlorethamine; C100099:tretazicar; C029492:aromatic NADH-dependent nitroreductase; D009601:Nitroreductases