title: The urease locus of Mycobacterium tuberculosis and its utilization for the demonstration of allelic exchange in Mycobacterium bovis bacillus Calmette-Guérin.
abstract: The ureABC genes of Mycobacterium tuberculosis were cloned. By using a set of degenerate primers corresponding to a conserved region of the urease enzyme (EC 3.5.1.5), a fragment of the expected size was amplified by PCR and was used to screen a M. tuberculosis cosmid library. Three open reading frames with extensive similarity to the urease genes from other organisms were found. The locus was mapped on the chromosome, using an ordered M. tuberculosis cosmid library. A suicide vector containing a ureC gene disrupted by a kanamycin marker (aph) was used to construct a urease-negative Mycobacterium bovis bacillus Calmette-Guérin mutant by allelic exchange involving replacement of the ureC gene with the aph::ureC construct. To our knowledge, allelic exchange has not been reported previously in the slow-growing mycobacteria. Homologous recombination will be an invaluable genetic tool for deciphering the mechanisms of tuberculosis pathogenesis, a disease that causes 3 x 10(6) deaths a year worldwide.
authors.affiliation: Unité de Génétique Mycobactérienne, Centre National de la Recherche Scientifique, Institut Pasteur 25, Paris, France.
authors.forename: J M
authors.initials: JM
authors.lastname: Reyrat
authors.forename: F X
authors.initials: FX
authors.lastname: Berthet
authors.forename: B
authors.initials: B
authors.lastname: Gicquel
mesh_terms: D000483:Alleles; D000595:Amino Acid Sequence; D001483:Base Sequence; D015139:Blotting, Southern; D002874:Chromosome Mapping; D016680:Genome, Bacterial; D015698:Genomic Library; D005838:Genotype; D008969:Molecular Sequence Data; D016254:Mutagenesis, Insertional; D009163:Mycobacterium bovis / Q000235:genetics*; D009169:Mycobacterium tuberculosis / Q000201:enzymology / Q000235:genetics*; D016133:Polymerase Chain Reaction; D011995:Recombination, Genetic; D017422:Sequence Analysis, DNA; D017386:Sequence Homology, Amino Acid; D013045:Species Specificity; D014510:Urease / Q000235:genetics*
chemical_list: D014510:Urease