MOLECULAR-CLONING OF THE LEUB GENES FROM MYCOBACTERIUM-BOVIS BCG AND MYCOBACTERIUM-TUBERCULOSIS

A gene responsible for the biosynthesis of leucine has been cloned by the complementation of the Escherichia coli leuB6 auxotroph mutant aft er transformation with the Mycobacterium bovis BCG genomic DNA library , which was constructed by ligating the partially digested BCG DNA wit h Sau3AI into the pUC19 digested with BamHI. Sequencing of the leuB ge ne of BCG revealed an ORF (open reading frame) of 1,011 bp encoding is opropylmalate dehydrogenase with a calculated molecular weight of 42 k Da. The leuB gene of Mycobacterium tuberculosis isolated from Korean t uberculosis patient is shown to be identical to that of BCG except one bp.