Ryan M J, Wells R D
Biochemistry. 1976 Aug 24;15(17):3778-82. doi: 10.1021/bi00662a021.
In vitro inhibitions by coumermycin A1 of DNA and RNA synthesis in toluenized cells were studied. In a sensitive strain, 50% inhibitions of replication and transcription were observed at 0.035 and 0.600 mug/ml, respectively. DNA synthesis in a toluenized-resistant mutant was 50% inhibited at 0.140 mug/ml of coumermycin A1, whereas RNA synthesis was unaffected at all concentrations tested. Studies with a mixture of toluenized-sensitive and -resistant bacteria ruled out the presence of a diffusable activator or inhibitor of coumermycin A1 action. Density label studies with toluenized pol A+ and pol A- strains indicated that replicative DNA synthesis was specifically inhibited, in agreement with the in vivo studies in the preceding paper of this issue (Ryan, M. J. (1976), Biochemistry 15). Highly purified Escherichia coli DNA polymerase III and RNA polymerase both were inhibited by this antibiotic. However, the high concentrations necessary for these inhibitions suggest that they are not biologically relevant. No interaction between DNA and coumermycin A1 was observed with the following analytical procedures: ultraviolet difference spectra, DNA absorbance-temperature transitions, equilibrium buoyant density centrifugation, and DNA cross-linking determinations.
研究了香豆霉素A1对甲苯处理细胞中DNA和RNA合成的体外抑制作用。在一个敏感菌株中，分别在0.035和0.600微克/毫升时观察到复制和转录的50%抑制。甲苯处理的抗性突变体中，在0.140微克/毫升香豆霉素A1时DNA合成被50%抑制，而在所有测试浓度下RNA合成均未受影响。对甲苯处理的敏感和抗性细菌混合物的研究排除了香豆霉素A1作用的可扩散激活剂或抑制剂的存在。对甲苯处理的pol A+和pol A-菌株的密度标记研究表明，复制性DNA合成受到特异性抑制，这与本期前一篇论文（Ryan, M. J. (1976), Biochemistry 15）中的体内研究结果一致。高度纯化的大肠杆菌DNA聚合酶III和RNA聚合酶均被这种抗生素抑制。然而，这些抑制所需的高浓度表明它们在生物学上不相关。通过以下分析程序未观察到DNA与香豆霉素A1之间的相互作用：紫外差光谱、DNA吸光度-温度转变、平衡浮力密度离心和DNA交联测定。
