Taniguchi H, Chang B, Abe C, Nikaido Y, Mizuguchi Y, Yoshida S I
Department of Microbiology, School of Medicine, University of Occupational and Environmental Health, Yahatanishiku, Kitakyusyu, Japan.
J Bacteriol. 1997 Aug;179(15):4795-801. doi: 10.1128/jb.179.15.4795-4801.1997.
We examined the molecular mechanisms of resistance to kanamycin and viomycin in Mycobacterium smegmatis. All of the M. smegmatis strains with high-level kanamycin resistance had a nucleotide substitution from A to G at position 1389 of the 16S rRNA gene (rrs). This position is equivalent to position 1408 of Escherichia coli, and mutation at this position is known to cause aminoglycoside resistance. Mutations from G to A or G to T at position 1473 of the M. smegmatis rrs gene were found in viomycin-resistant mutants which had been designated vicB mutants in our earlier studies. Using the M. smegmatis conjugation system, we confirmed that these mutations indeed contributed to kanamycin and viomycin resistance, and kanamycin susceptibility was dominant over resistance in a heterogenomic strain. Additional experiments showed that three of four Mycobacterium tuberculosis strains with high-level kanamycin resistance had a mutation from A to G at position 1400, which was equivalent to position 1389 of M. smegmatis.
我们研究了耻垢分枝杆菌对卡那霉素和紫霉素耐药的分子机制。所有对卡那霉素具有高水平耐药性的耻垢分枝杆菌菌株，其16S rRNA基因（rrs）的第1389位核苷酸发生了从A到G的替换。该位置相当于大肠杆菌的第1408位，已知此位置的突变会导致氨基糖苷类耐药。在我们早期研究中被指定为vicB突变体的紫霉素耐药突变体中，发现耻垢分枝杆菌rrs基因第1473位有从G到A或从G到T的突变。利用耻垢分枝杆菌接合系统，我们证实这些突变确实导致了对卡那霉素和紫霉素的耐药，并且在异基因组菌株中卡那霉素敏感性优于耐药性。进一步的实验表明，四株对卡那霉素具有高水平耐药性的结核分枝杆菌菌株中有三株在第1400位发生了从A到G的突变，该位置相当于耻垢分枝杆菌的第1389位。
