Funatsuki K, Tanaka R, Inagaki S, Konno H, Katoh K, Nakamura H
Aburahi Laboratories, Shionogi & Co., Ltd., Koka, Shiga, Japan.
Biol Pharm Bull. 1998 Jul;21(7):667-72. doi: 10.1248/bpb.21.667.
DNA gyrases were constructed to possess the quinolone-resistant (D87N in GyrA or K447E in GyrB) and acrB (S759R-R760C in GyrB) mutations and their sensitivities to acriflavine and oxolinic acid were examined. Both quinolone-resistant mutations in GyrA and GyrB increased acriflavine sensitivities in the supercoiling assay irrespective of the co-presence of the acrB mutation. In the DNA binding assay, however, the hypersensitvity caused by the GyrB (K447E) mutation was observed only in the co-presence of the acrB mutation; the presence of the acrB mutation, which not affecting acriflavine sensitivity, reduces the extent of DNA binding, as reported previously. Thus, the quinolone-resistant mutation site in GyrB is likely to be involved in DNA binding which is not detectable in acrB+ gyrase. Furthermore, oxolinic acid was found to enhance DNA binding of the gyrase having GyrB (acrB-K447E), supporting a recent proposal that quinolone binding to the DNA-gyrase complex does not require DNA breakage.
构建了具有喹诺酮抗性（GyrA中的D87N或GyrB中的K447E）和acrB（GyrB中的S759R - R760C）突变的DNA促旋酶，并检测了它们对吖啶黄素和恶喹酸的敏感性。无论acrB突变是否同时存在，GyrA和GyrB中的喹诺酮抗性突变在超螺旋检测中均增加了对吖啶黄素的敏感性。然而，在DNA结合检测中，仅在acrB突变同时存在时才观察到由GyrB（K447E）突变引起的超敏性；如先前报道，不影响吖啶黄素敏感性的acrB突变的存在会降低DNA结合程度。因此，GyrB中的喹诺酮抗性突变位点可能参与了在acrB +促旋酶中无法检测到的DNA结合。此外，发现恶喹酸增强了具有GyrB（acrB - K447E）的促旋酶的DNA结合，支持了最近的一项提议，即喹诺酮与DNA - 促旋酶复合物的结合不需要DNA断裂。
