Lesley S M, Behki R M
J Bacteriol. 1967 Dec;94(6):1837-45. doi: 10.1128/jb.94.6.1837-1845.1967.
The effect of the new antibiotic, myxin, on the syntheses of deoxyribonucleic acid (DNA), ribonucleic acid (RNA), and protein in Escherichia coli (strains B and 15T(-)) was examined. Within 7 min of the addition of myxin at 5 mug/ml, the synthesis of new bacterial DNA was almost completely inhibited. This was followed by an extensive degradation of the pre-existing DNA to an acid-soluble form. All of the evidence indicated that the primary effect of the antibiotic was on cellular DNA. The synthesis of RNA was completely inhibited after 15 min of exposure to myxin (5 mug/ml), and the synthesis of protein was markedly reduced after 30 min. There was no measurable breakdown of either RNA or protein in the myxin-treated cells. A marked stimulation of (14)C-uracil incorporation was found in the presence of myxin in 15T(-) cells only. This did not result from an increased rate of RNA synthesis but was due to an increase in the proportion of exogenous uracil, relative to endogenous uracil, incorporated into cellular RNA. This probably reflected a partial inhibition of the biosynthesis of uridine monophosphate from orotate. At 4.5 mug of myxin per ml and with 0.8 x 10(8) cells per ml, 50% of the antibiotic was reduced in 15 min from the biologically active oxidized form to the biologically inactive state. Under these conditions, a maximum of 0.6% (27 mumug/ml) of the myxin was retained in the cells.
研究了新型抗生素粘菌素对大肠杆菌（B株和15T(-)株）中脱氧核糖核酸（DNA）、核糖核酸（RNA）和蛋白质合成的影响。在加入5微克/毫升粘菌素后的7分钟内，新细菌DNA的合成几乎完全被抑制。随后，先前存在的DNA被大量降解为酸溶性形式。所有证据表明，该抗生素的主要作用是针对细胞DNA。暴露于粘菌素（5微克/毫升）15分钟后，RNA的合成完全被抑制，30分钟后蛋白质的合成显著减少。在经粘菌素处理的细胞中，RNA和蛋白质均未检测到降解。仅在15T(-)细胞中，在粘菌素存在的情况下发现（14）C-尿嘧啶掺入有明显刺激作用。这并非由于RNA合成速率增加，而是由于相对于内源性尿嘧啶，掺入细胞RNA中的外源性尿嘧啶比例增加。这可能反映了从乳清酸合成尿苷单磷酸的生物合成受到部分抑制。在每毫升4.5微克粘菌素且每毫升有0.8×10(8)个细胞的情况下，15分钟内50%的抗生素从具有生物活性的氧化形式还原为无生物活性的状态。在这些条件下，细胞中最多保留0.6%（27微克/毫升）的粘菌素。
