title: Trypanosoma brucei MRE11 is non-essential but influences growth, homologous recombination and DNA double-strand break repair.
abstract: MRE11 is a conserved multi-functional protein that is important for maintaining genomic integrity in yeast and mammalian cells. By database searching, we identified a full-length candidate MRE11 on Trypanosoma brucei chromosome II. We subsequently cloned and sequenced the corresponding gene from the Lister 427 strain. MRE11 is a single copy gene that encodes an 83 kDa protein of 763 amino acids. GFP-MRE11 and Ty1-MRE11 fusion proteins localized to the nucleus of bloodstream and procyclic T. brucei. Interestingly, Ty1-MRE11 associated, to some extent, with telomeres of procyclic but not bloodstream forms. This association appears cell-cycle dependent, with the highest co-localization in G1 cells. We were able to generate an MRE11 null mutant in bloodstream forms, indicating that it is non-essential. However, the null mutant was impaired in homologous recombination, as evidenced by the reduced integration efficiency of transfected DNA. A conditional null mutant, containing a tetracycline-inducible ectopic Ty1-MRE11, exhibited reduced growth and plating efficiency and increased sensitivity to DNA double-strand breaks, induced by methyl methanesulphonate or ionizing radiation, in the absence of tetracycline.
authors.affiliation: Laboratory of Molecular Parasitology, The Rockefeller University, Box 185, 1230 York Avenue, New York, NY 10021-6399, USA.
authors.forename: Kevin S W
authors.initials: KS
authors.lastname: Tan
authors.forename: Simone T G
authors.initials: ST
authors.lastname: Leal
authors.forename: George A M
authors.initials: GA
authors.lastname: Cross
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D002455:Cell Division; D003001:Cloning, Molecular; D004249:DNA Damage; D004260:DNA Repair; D005786:Gene Expression Regulation; D008957:Models, Genetic; D008969:Molecular Sequence Data; D009154:Mutation; D015800:Protozoan Proteins / Q000235:genetics / Q000502:physiology*; D011995:Recombination, Genetic; D016415:Sequence Alignment; D013752:Tetracycline / Q000494:pharmacology; D014346:Trypanosoma brucei brucei / Q000187:drug effects / Q000235:genetics* / Q000254:growth & development
chemical_list: D015800:Protozoan Proteins; D013752:Tetracycline