| Autor: |
Maus, Courtney E., Plikaytis, Bonnie B., Shinnick, Thomas M. |
| Zdroj: |
Antimicrobial Agents and Chemotherapy; February 2005, Vol. 49 Issue: 2 p571-577, 7p |
| Abstrakt: |
ABSTRACTCapreomycin, an important drug for the treatment of multidrug-resistant tuberculosis, is a macrocyclic peptide antibiotic produced by Saccharothrix mutabolissubspecies capreolus. The basis of resistance to this drug was investigated by isolating and characterizing capreomycin-resistant strains of Mycobacterium smegmatisand Mycobacterium tuberculosis. Colonies resistant to capreomycin were recovered from a library of transposon-mutagenized M. smegmatis. The transposon insertion site of one mutant was mapped to an open reading frame in the unfinished M. smegmatisgenome corresponding to the tlyAgene (Rv1694) in the M. tuberculosisH37Rv genome. In M. smegmatisspontaneous capreomycin-resistant mutants, the tlyAgene was disrupted by one of three different naturally occurring insertion elements. Genomic DNAs from pools of transposon mutants of M. tuberculosisH37Rv were screened by PCR by using primers to the tlyAgene and the transposon to detect mutants with an insertion in the tlyAgene. One capreomycin-resistant mutant was recovered that contained the transposon inserted at base 644 of the tlyAgene. Complementation with the wild-type tlyAgene restored susceptibility to capreomycin in the M. smegmatisand M. tuberculosis tlyAtransposon mutants. Mutations were found in the tlyAgenes of 28 spontaneous capreomycin-resistant mutants generated from three different M. tuberculosisstrains and in the tlyAgenes of capreomycin-resistant clinical isolates. In in vitro transcription-translation assays, ribosomes from tlyAmutant but not tlyA+strains resist capreomycin inhibition of transcription-translation. Therefore, TlyA appears to affect the ribosome, and mutation of tlyAconfers capreomycin resistance. |
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