Characterization of components of the mismatch repair machinery in Trypanosoma brucei.
Mismatch repair is one of a number of DNA repair pathways that cells possess to deal with damage to their genome. Mismatch repair is concerned with the recognition and correction of incorrectly paired bases, which can be base-base mismatches or insertions or deletions of a few bases, and appears to have been conserved throughout evolution. Primarily, this is concerned with increasing the fidelity of DNA replication, but also has important roles in the regulation of homologous recombination and the correction of chemical damage. In this study, we describe five genes in the protistan parasite Trypanosoma brucei that are likely to be involved in nuclear mismatch repair. The predicted T. brucei mismatch repair genes are diverged compared with their likely counterparts in the other eukaryotes examined to date. To demonstrate that these do indeed encode a functional nuclear mismatch repair system, we made T. brucei null mutants in two of the genes, MSH2 and MLH1, that are likely to be central to the functioning of the mismatch repair machinery. These mutations resulted in increased rates of sequence variation at a number of microsatellite loci in the parasite genome, and led to increased tolerance to the alkylating agent N-methyl-N'-nitro-N-nitrosoguanidine, both phenotypes consistent with mismatch repair impairment.
Bell
Joanna S
JS
The Wellcome Centre for Molecular Parasitology, University of Glasgow, Anderson College, 56 Dumbarton Road, Glasgow G11 6NU, UK.
Harvey
Timothy I
TI
Sims
Anne-Marie
AM
McCulloch
Richard
R
D000251:Adenosine Triphosphatases / Q000737:chemistry / Q000235:genetics; D000595:Amino Acid Sequence; D000818:Animals; D020137:Base Pair Mismatch / Q000235:genetics*; D001483:Base Sequence; D017124:Conserved Sequence; D017931:DNA Primers; D004260:DNA Repair / Q000235:genetics*; D017353:Gene Deletion; D019077:Helix-Turn-Helix Motifs; D008969:Molecular Sequence Data; D016366:Open Reading Frames; D010802:Phylogeny; D017386:Sequence Homology, Amino Acid; D014346:Trypanosoma brucei brucei / Q000145:classification / Q000235:genetics*
D017931:DNA Primers; D000251:Adenosine Triphosphatases