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Unravelling the role of SNM 1 in the DNA repair system of T rypanosoma brucei
Author(s) -
Sullivan James A.,
Tong Jie Lun,
Wong Martin,
Kumar Ambika,
Sarkar Hajrah,
Ali Sarah,
Hussein Ikran,
Zaman Iqra,
Meredith Emma Louise,
Helsby Nuala A.,
Hu Longqin,
Wilkinson Shane R.
Publication year - 2015
Publication title -
molecular microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.857
H-Index - 247
eISSN - 1365-2958
pISSN - 0950-382X
DOI - 10.1111/mmi.12973
Subject(s) - biology , trypanosoma brucei , mutant , dna damage , dna , enzyme , yeast , cdc42 , dna repair , mechanism of action , biochemistry , gene , phenotype , saccharomyces cerevisiae , ectopic expression , microbiology and biotechnology , genetics , in vitro , gtpase
Summary 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 PSO 2/ SNM 1 nucleases. Here, we report that T rypanosoma brucei , the causative agent of A frican trypanosomiasis, possesses a bona fide member of this family (called TbSNM 1) with expression of the parasite enzyme able to suppress the sensitivity yeast pso2Δ mutants display towards mechlorethamine, an ICL ‐inducing compound. By disrupting the T b snm1 gene, we demonstrate that TbSNM 1 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 T b snm1 . 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.