DELETIONS AT SHORT DIRECT REPEATS AND BASE SUBSTITUTIONS ARE CHARACTERISTIC MUTATIONS FOR BLEOMYCIN-INDUCED DOUBLE-STRAND AND SINGLE-STRAND BREAKS, RESPECTIVELY, IN A HUMAN SHUTTLE VECTOR SYSTEM
DELETIONS AT SHORT DIRECT REPEATS AND BASE SUBSTITUTIONS ARE CHARACTERISTIC MUTATIONS FOR BLEOMYCIN-INDUCED DOUBLE-STRAND AND SINGLE-STRAND BREAKS, RESPECTIVELY, IN A HUMAN SHUTTLE VECTOR SYSTEM
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DOI：
10.1093/nar/23.16.3224
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发表时间：
1995-08-25
影响因子：
14.9
通讯作者：
JORGENSEN, TJ
中科院分区：
文献类型：
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作者：
DAR, ME;JORGENSEN, TJ
利用拟放射药物博莱霉素，我们测定了穿梭载体pZ189的DNA链断裂在人成纤维细胞中的诱变潜力，博莱霉素处理条件下产生链断裂的3‘-磷酸乙醇酸末端占可检测到的剂量依赖性损伤的95%，这一端组的断裂占电离辐射所产生的链断裂的50%。我们报告说，这种链断裂是诱变损伤。突变的类型在很大程度上取决于质粒上的链断裂类型(即单链断裂与双链断裂)，用纯化的DNA形式进行的突变研究表明，含镍质粒(即含有单链断裂的载体)主要产生碱基替换，其中大多数是多重替换，推测其起源于容易出错的链断裂位点的聚合酶活性，而线形质粒(即含有双链断裂的载体)的修复主要导致短直接重复序列的缺失，表明参与了非法重组。这些数据描述了人类细胞中单链和双链断裂所产生的突变的性质，并表明直接重复序列上的缺失可能是DNA双链断裂处理过程中的“标志性”突变。
Using the radiomimetic drug, bleomycin, we have determined the mutagenic potential of DNA strand breaks in the shuttle vector pZ189 in human fibroblasts, The bleomycin treatment conditions used produce strand breaks with 3'-phosphoglycolate termini as >95% of the detectable dose-dependent lesions, Breaks with this end group represent 50% of the strand break damage produced by ionizing radiation. We report that such strand breaks are mutagenic lesions. The type of mutation produced is largely determined by the type of strand break on the plasmid (i.e. single versus double), Mutagenesis studies with purified DNA forms showed that nicked plasmids (i.e. those containing single-strand breaks) predominantly produce base substitutions, the majority of which are multiples, which presumably originate from error prone polymerase activity at strand break sites, In contrast, repair of linear plasmids (i.e. those containing double-strand breaks) mainly results in deletions at short direct repeat sequences, indicating the involvement of illegitimate recombination. The data characterize the nature of mutations produced by single- and double-strand breaks in human cells, and suggests that deletions at direct repeats may be a 'signature' mutation for the processing of DNA double-strand breaks.