title: Production of unmarked mutations in mycobacteria using site-specific recombination.
abstract: Gene disruption experiments play an important role in the functional characterization of genes in mycobacteria and rely mostly on the use of one or two antibiotic resistance markers. We have developed a system for mycobacteria which features both the advantages of the use of antibiotic resistance markers for gene disruption experiments and the ability to efficiently rescue the marker leaving an unmarked mutation on the chromosome. This new genetic tool relies on the transposon gammadelta site-specific recombination system. A res-OmegaKm-res cassette was used to generate an insertional mutation by allelic exchange both in Mycobacterium smegmatis and Mycobacterium bovis BCG. Upon expression in the mutated strains of tnpR, the transposon gammadelta resolvase gene, res-OmegaKm-res, was excised efficiently leaving behind a single res sequence at the mutated locus. A plasmid was engineered allowing expression of tnpR from an easily curable mycobacterial vector. This system will be useful for simple construction of unmarked mutations or repeated use of the same antibiotic marker to generate multiple mutants.
authors.affiliation: Département 'Mécanismes Moléculaires des Infections Mycobactériennes', Institut de Pharmacologie, Centre National de la Recherche Scientifique, Université Paul Sabatier, 31077 Cedex, Toulouse, France.
authors.forename: Wladimir
authors.initials: W
authors.lastname: Malaga
authors.forename: Esther
authors.initials: E
authors.lastname: Perez
authors.forename: Christophe
authors.initials: C
authors.lastname: Guilhot
mesh_terms: D003001:Cloning, Molecular; D004251:DNA Transposable Elements; D005798:Genes, Bacterial; D007613:Kanamycin Resistance / Q000235:genetics; D008957:Models, Genetic; D016254:Mutagenesis, Insertional / Q000379:methods*; D016297:Mutagenesis, Site-Directed; D009154:Mutation; D009161:Mycobacterium / Q000145:classification / Q000235:genetics*; D010957:Plasmids / Q000235:genetics / Q000378:metabolism; D045522:Recombinases; D011995:Recombination, Genetic; D019895:Transposases / Q000235:genetics; D045564:Transposon Resolvases
chemical_list: D004251:DNA Transposable Elements; D045522:Recombinases; D019895:Transposases; D045564:Transposon Resolvases