Kane J F, Wainscott V J, Hurt M A
J Bacteriol. 1979 Feb;137(2):1028-30. doi: 10.1128/jb.137.2.1028-1030.1979.
Several independent, spontaneous rifampin-resistant mutants of Bacillus subtilis were isolated and found to have an increased resistance to trimethoprim, an inhibitor of dihydrofolate reductase. This increased resistance in the rif mutants was the result of a specific threefold increase in the activity of dihydrofolate reductase, since six other enzymes examined remained unchanged. This increased level of dihydrofolate reductase and the trimethoprim resistance were cotransformed (100%) with the rif marker. These results suggest that the RNA polymerase is altered in its recognition of the gene that specifies dihydrofolate reductase.
分离出了几株独立的、自发产生的对利福平耐药的枯草芽孢杆菌突变体，发现它们对二氢叶酸还原酶抑制剂甲氧苄啶的耐药性增强。利福平突变体中这种增强的耐药性是二氢叶酸还原酶活性特异性增加三倍的结果，因为所检测的其他六种酶保持不变。二氢叶酸还原酶的这种升高水平和甲氧苄啶耐药性与利福平标记共转化（100%）。这些结果表明，RNA聚合酶在识别指定二氢叶酸还原酶的基因方面发生了改变。
