DNA sequence specificity of mitomycin cross-linking.
DNA sequence specificity of mitomycin cross-linking.
复制标题
丝裂霉素交联的 DNA 序列特异性。
DOI：
10.1021/bi00435a041
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发表时间：
1989
期刊：
影响因子：
2.9
通讯作者：
Crothers,DM
中科院分区：
文献类型：
--
作者：
Teng,SP;Woodson,SA;Crothers,DM
Sally P. Teng，Sarah A. Woodson，and DonaldM. Crothers* 耶鲁大学化学系，纽黑文，康涅狄格州06511于1988年8月3日收到;修订稿于1989年1月13日收到摘要：使用凝胶电泳分析，我们表明由N-甲基丝裂霉素A、其氮丙啶三烯和丝裂霉素C交联的靶DNA序列是CpG，强烈优先于GpC。每个CpG位点的产量随着连续CpG序列数量的增加而增加。分子模拟显示，与GpC相比，丝裂霉素交联CpG的能量之间没有系统差异。然而，CpG序列中鸟嘌呤氨基之间的距离与交联加合物中的距离几乎相同，而GpC位点处的氨基分离在起始DNA中比在加合物中大得多。我们认为第二反应中心在CpG中的有利位置大大加速了交联反应的第二步。如竞争试验所示，丝裂霉素与A* T和GC序列非共价结合的效果相同，尽管唯一产生明显交联的序列是CpG。发现N-甲基丝裂霉素A和它的氮杂环丙亚胺是比丝裂霉素C更好的交联剂。自从它们在1956年被发现以来（Hata等人，1956），丝裂霉素由于其作为化学治疗剂的效力而受到广泛关注（雷默，1956），尽管大部分工作都集中在该组的一个成员丝裂霉素C（MC）上。1 MC有三个主要官能团：醌，氨基甲酸酯和氮丙啶，但药物在醌形式下没有活性（图1）。活化需要酶或化学还原（Iyer & Szybalski，1964 a）或弱酸处理（Tomasz & Lipman，1979），将MC转化为能够与DNA发生单官能和/或双官能共价相互作用的烷化剂（Iyer & Szybalski，1964; Mercado & Tomasz，1972）。MC直接作用于DNA以抑制DNA合成（Goldberg & Friedman，1971），从而阻止细胞分裂并降低细胞活力。尽管单官能烷基化发生的频率比双官能烷基化高10-20倍（Iyer & Szybalski，1964; Weissbach & Lisio，1965），但交联被认为是对癌细胞的致死作用的来源（Iyer & Szybalski，1967）。最近，已报道单官能烷基化引起显著的DNA损伤（Mercado
Sally P. Teng, Sarah A. Woodson, and DonaldM. Crothers* Department of Chemistry, Yale University, New Haven, Connecticut 06511 Received August 3, 1988; Revised Manuscript Received January 13, 1989 abstract: Using a gel electrophoresis assay, we show that the target DNA sequence cross-linked by iV-methylmitomycin A, its aziridinomitosene, and mitomycin C is CpG, in strong preference over GpC. The yield per CpG siteincreases as the number of successive CpG sequences increases. Molecular modeling reveals no systematic difference between the energies of mitomycin cross-linksat CpG in comparison with GpC. However, the distance between guanine amino groups in CpG sequences is nearly the same as the distance in the cross-linked adduct, whereas the amino group separation at GpC sites is substantially larger in the starting DNA than in the adduct. We suggest that the favorable placement of the second reaction center in CpG greatly accelerates the second step in the cross-linking reaction. As shown by a competition assay, mitomycins bind A* T and GC sequences noncovalently equally well, even though the only sequence that yields appreciable cross-linking is CpG. 7V-Methylmitomycin A and its aziridinomitosene are found to be better cross-linking agents than is mitomycin C.Since their discovery in 1956 (Hata et al., 1956), mitomycins have received muchattention due to their potency as che-motherapeutic agents (Remer, 1956) although most of the work has been focused on one member of the group, mitomycin C (MC). 1 MC has three major functional groups: quinone, carbamate, and aziridine, but the drug is not active in the quinone form (Figure 1). Activation requires either enzymatic or chemical reduction (Iyer & Szybalski, 1964a), or mild acidic treatment (Tomasz & Lipman, 1979), converting MC to alkylating agents capable of monofunctional and/or bifunctional covalent interaction with DNA (Iyer & Szybalski, 1964; Mercado & Tomasz, 1972). MC acts directly on DNA to inhibit DNA synthesis (Goldberg & Friedman, 1971), thus preventing cell division and diminishing cell viability. Although monofunctional alkylation occurs 10-20 times more frequently than bifunctional alkylation (Iyer & Szybalski, 1964; Weissbach & Lisio, 1965), cross-linking has been considered to be the source of the lethal effect on cancer cells (Iyer & Szybalski, 1967). More recently, monofunctional alkylation has been reported to cause significant DNA damage (Mercado