CYTOTOXICITY OF ALKYLATING AGENTS TOWARDS SENSITIVE AND RESISTANT STRAINS OF ESCHERICHIA COLI IN RELATION TO EXTENT AND MODE OF ALKYLATION OF CELLULAR MACROMOLECULES AND REPAIR OF ALKYLATION LESIONS IN DEOXYRIBONUCLEIC ACIDS
CYTOTOXICITY OF ALKYLATING AGENTS TOWARDS SENSITIVE AND RESISTANT STRAINS OF ESCHERICHIA COLI IN RELATION TO EXTENT AND MODE OF ALKYLATION OF CELLULAR MACROMOLECULES AND REPAIR OF ALKYLATION LESIONS IN DEOXYRIBONUCLEIC ACIDS
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DOI：
10.1042/bj1090433
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发表时间：
1968-01-01
影响因子：
4.1
通讯作者：
BROOKES, P
中科院分区：
文献类型：
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作者：
LAWLEY, PD;BROOKES, P
1.本文定量研究了大肠杆菌B/r和Bs-1菌株经单、双功能硫芥、甲磺酸甲酯和碘乙酰胺处理后，菌落形成能力的存活与细胞DNA、RNA和蛋白质烷基化程度的关系。2.在细胞中，MUR和甲基甲磺酸酯与核酸发生反应，与以前在体外化学研究中发现的方式相同，并与蛋白质发生反应。碘乙酰胺仅与蛋白质反应，主要与半胱氨酸残基的巯基反应。3.阻止细胞分裂所需的细胞成分的烷基化程度根据细菌菌株和烷基化剂的性质而变化很大。4.在给定的烷化剂剂量下，敏感菌株和耐药菌株的烷基化程度没有显著差异。5.在用双官能硫芥进行烷基化后，证明了从耐药菌株B/r和15 T −的细胞DNA中去除烷基;产物二（鸟嘌呤-7-乙基）硫化物（与单官能烷基化相反，具有双官能烷基化特征）被选择性地去除;这种效应的时间尺度表明是酶机制而不是化学机制。6.敏感菌株Bs-1以这种方式仅在非常低的烷基化程度下从DNA上去除烷基。当用碘乙酰胺、吖啶黄素或咖啡因处理对芥子气作用敏感时，对应于平均致死剂量的细胞DNA烷基化程度降低到该菌株基因组中约3个二（鸟嘌呤-7-乙基）硫化物分子。7.相对大量的单官能烷基化每个基因组可以承受这种敏感的菌株。碘乙酰胺有最弱的细胞毒性作用的代理商的调查;甲基甲磺酸酯的效果显着弱于单功能的硫芥，这反过来又弱于双功能的硫芥。8.研究了硫诱变剂对敏感和抗性菌株核酸合成的影响。在低剂量下，两种菌株的DNA合成均以剂量依赖性方式受到抑制，但RNA和蛋白质合成不受影响。9.在E. coliBs-1则被低剂量的muplatin永久性抑制。在耐药菌株15 T-和B/r中，在剂量依赖性时滞后观察到DNA合成的特征性恢复。在平均致死剂量范围内的低剂量下可显示出这种效应。10.用同位素预标记细胞DNA，研究了不同浓度的三聚氰胺对DNA稳定性的影响。与耐药菌株的剂量依赖性释放的DNA核苷酸材料成酸溶性形式被发现，这是更广泛的双功能的芥末（约400个核苷酸释放每个DNA烷基化）比单功能的芥末（约10个核苷酸每个烷基化）。与敏感的菌株没有剂量依赖性的释放被发现，虽然DNA是不太稳定的细胞烷基化独立。11.结果进行了讨论的概念，烷基化的细胞DNA诱导病变干扰DNA复制，但可以酶“修复”。这些病变的可能性质进行了讨论，在已知的烷化剂与DNA的反应。
1. A quantitative study was made of the relationship between survival of colony-forming ability inEscherichia colistrains B/r and Bs–1and the extents of alkylation of cellular DNA, RNA and protein after treatment with mono- or di-functional sulphur mustards, methyl methanesulphonate or iodoacetamide. 2. The mustards and methyl methanesulphonate react with nucleic acids in the cells, in the same way as found previously from chemical studiesin vitro, and with proteins. Iodoacetamide reacts only with protein, principally with the thiol groups of cysteine residues. 3. The extents of alkylation of cellular constituents required to prevent cell division vary widely according to the strain of bacteria and the nature of the alkylating agent. 4. The extents of alkylation of the sensitive and resistant strains at a given dose of alkylating agent do not differ significantly. 5. Removal of alkyl groups from DNA of cells of the resistant strains B/r and 15T−after alkylation with difunctional sulphur mustard was demonstrated; the product di(guanin-7-ylethyl) sulphide, characteristic of di- as opposed to mono-functional alkylation, was selectively removed; the time-scale of this effect suggests an enzymic rather than a chemical mechanism. 6. The sensitive strain Bs–1removed alkyl groups from DNA in this way only at very low extents of alkylation. When sensitized to mustard action by treatment with iodoacetamide, acriflavine or caffeine, the extent of alkylation of cellular DNA corresponding to a mean lethal dose was decreased to approximately 3 molecules of di(guanin-7-ylethyl) sulphide in the genome of this strain. 7. Relatively large numbers of monofunctional alkylations per genome can be withstood by this sensitive strain. Iodoacetamide had the weakest cytotoxic action of the agents investigated; methyl methanesulphonate was significantly weaker in effect than the monofunctional sulphur mustard, which was in turn weaker than the difunctional sulphur mustard. 8. Effects of the sulphur mustards on nucleic acid synthesis in sensitive and resistant strains were studied. DNA synthesis was inhibited in both strains at low doses in a dose-dependent manner, but RNA and protein synthesis were not affected in this way. 9. DNA synthesis inE. coliBs–1was permanently inhibited by low doses of mustards. In the resistant strains 15T−and B/r a characteristic recovery in DNA synthesis was observed after a dose-dependent time-lag. This effect could be shown at low doses in the region of the mean lethal dose. 10. Cellular DNA was isotopically prelabelled and the effect of mustards on stability of DNA was investigated. With resistant strains a dose-dependent release of DNA nucleotide material into acid-soluble form was found; this was much more extensive with the difunctional mustard (about 400 nucleotides released per DNA alkylation) than with the monofunctional mustard (about 10 nucleotides per alkylation). With the sensitive strain no dose-dependent release was found, though the DNA was less stable independent of cellular alkylation. 11. The results are discussed in terms of the concepts that alkylation of cellular DNA induces lesions which interfere with DNA replication, but which can be enzymically ‘repaired’. The possible nature of these lesions is discussed in terms of the known reactions of the alkylating agents with DNA.