title: Formation of linear amplicons with inverted duplications in Leishmania requires the MRE11 nuclease.
abstract: Extrachromosomal DNA amplification is frequent in the protozoan parasite Leishmania selected for drug resistance. The extrachromosomal amplified DNA is either circular or linear, and is formed at the level of direct or inverted homologous repeated sequences that abound in the Leishmania genome. The RAD51 recombinase plays an important role in circular amplicons formation, but the mechanism by which linear amplicons are formed is unknown. We hypothesized that the Leishmania infantum DNA repair protein MRE11 is required for linear amplicons following rearrangements at the level of inverted repeats. The purified LiMRE11 protein showed both DNA binding and exonuclease activities. Inactivation of the LiMRE11 gene led to parasites with enhanced sensitivity to DNA damaging agents. The MRE11(-/-) parasites had a reduced capacity to form linear amplicons after drug selection, and the reintroduction of an MRE11 allele led to parasites regaining their capacity to generate linear amplicons, but only when MRE11 had an active nuclease activity. These results highlight a novel MRE11-dependent pathway used by Leishmania to amplify portions of its genome to respond to a changing environment.
authors.affiliation: Centre de Recherche en Infectiologie du CHU de Québec, Quebec City, Québec, Canada.
authors.forename: Marie-Claude N
authors.initials: MC
authors.lastname: Laffitte
authors.affiliation: Centre de Recherche en Infectiologie du CHU de Québec, Quebec City, Québec, Canada; Genome Stability Laboratory, CHU de Quebec Research Center, HDQ Pavillon, Oncology Axis, Quebec City, Québec, Canada; Department of Molecular Biology, Medical Biochemistry and Pathology, Laval University, Quebec City, Québec, Canada.
authors.forename: Marie-Michelle
authors.initials: MM
authors.lastname: Genois
authors.affiliation: Centre de Recherche en Infectiologie du CHU de Québec, Quebec City, Québec, Canada.
authors.forename: Angana
authors.initials: A
authors.lastname: Mukherjee
authors.affiliation: Centre de Recherche en Infectiologie du CHU de Québec, Quebec City, Québec, Canada.
authors.forename: Danielle
authors.initials: D
authors.lastname: Légaré
authors.affiliation: Genome Stability Laboratory, CHU de Quebec Research Center, HDQ Pavillon, Oncology Axis, Quebec City, Québec, Canada; Department of Molecular Biology, Medical Biochemistry and Pathology, Laval University, Quebec City, Québec, Canada.
authors.forename: Jean-Yves
authors.initials: JY
authors.lastname: Masson
authors.affiliation: Centre de Recherche en Infectiologie du CHU de Québec, Quebec City, Québec, Canada.
authors.forename: Marc
authors.initials: M
authors.lastname: Ouellette
mesh_terms: D000818:Animals; D002478:Cells, Cultured; D045643:DNA Repair Enzymes / Q000235:genetics / Q000502:physiology*; D004720:Endonucleases / Q000235:genetics / Q000502:physiology*; D005784:Gene Amplification; D020440:Gene Duplication; D059647:Gene-Environment Interaction; D017125:Genes, Protozoan; D006801:Humans; D018314:Leishmania infantum / Q000235:genetics*; D016296:Mutagenesis / Q000235:genetics; D030781:Organisms, Genetically Modified; D012091:Repetitive Sequences, Nucleic Acid; D057345:Sequence Inversion; D061987:Sf9 Cells; D018411:Spodoptera
chemical_list: D004720:Endonucleases; D045643:DNA Repair Enzymes