Abstract: The invention relates to a novel enzyme involved in the biosynthesis of mycolic acids and to the use thereof for the screening of antibiotics, especially antimycobacterials. The invention more particularly relates to the Pks13 protein which catalyzes Claisen condensation or malonic condensation in mycolates between an acyl-CoA molecule or an acyl-AMP molecule and an acylmalonyl-CoA molecule to form an intermediate ?-cEto acyl or ?-cEto ester.

Abstract: The present invention pertains to the use of a PptT protein, as a target for screening compounds for identifying those having an antibiotic activity, especially against a pathogenic bacterium containing mycolic acids. The invention also concerns an in vitro screening process for identifying compounds having an antibiotic activity, by measuring the activity of a PptT protein in the presence or absence of said compounds.

Abstract: The invention relates to a novel enzyme involved in the biosynthesis of mycolic acids and to the use thereof for the screening of antibiotics, especially antimycobacterials. The invention more particularly relates to the Pks13 protein which catalyzes Claisen condensation or malonic condensation in mycolates between an acyl-CoA molecule or an acyl-AMP molecule and an acylmalonyl-CoA molecule to form an intermediate ?-cEto acyl or ?-cEto ester.

Abstract: This invention provides recombinant mycobacterium strains of pathogenic origin that have been attenuated by the inactivation of a gene coding for a metabolic protein, specifically a gene coding for a protein necessary for the biosynthesis of a purine or a pyrimidine base, and more precisely, the purC gene that codes for an enzyme of the metabolic pathway of purine biosynthesis. The recombinant mycobacterium of this invention have a reduced capacity to propagate in a mammalian host, but remain viable in the host for a period of time sufficient to induce an protective immune response against the natural pathogenic mycobacterium counterpart.

Abstract: This invention provides recombinant mycobacterium strains of pathogenic origin that have been attenuated by the inactivation of a gene coding for a metabolic protein, specifically a gene coding for a protein necessary for the biosynthesis of a purine or a pyrimidine base, and more precisely, the purC gene that codes for an enzyme of the metabolic pathway of purine biosynthesis. The recombinant mycobacterium of this invention have a reduced capacity to propagate in a mammalian host, but remain viable in the host for a period of time sufficient to induce an protective immune response against the natural pathogenic mycobacterium counterpart.

Abstract: A process for replacing a nucleotide sequence in the genome of a mycobacterium strain comprises the steps of:a) providing a vector containing SacB gene coding for levane saccharase enzyme and a nucleotide sequence of interest;b) transfecting the mycobacterium strain with the vector;c) selecting clones of the resulting transfected mycobacteria for replacement of the nucleotide sequence of interest by propagating the transfected clones in a culture medium supplemented with sucrose; andd) isolating the recombinant strain.The process is useful for positive selection of allelic exchange mutants, such as in Mycobacterium tuberculosis complex.