REPAIR OF DNA CONTAINING INTERSTRAND CROSSLINKS IN ESCHERICHIA-COLI - SEQUENTIAL EXCISION AND RECOMBINATION
REPAIR OF DNA CONTAINING INTERSTRAND CROSSLINKS IN ESCHERICHIA-COLI - SEQUENTIAL EXCISION AND RECOMBINATION
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DOI：
10.1073/pnas.70.4.1064
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发表时间：
1973-01-01
影响因子：
11.1
通讯作者：
COLE, RS
中科院分区：
文献类型：
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作者：
COLE, RS
大肠杆菌中由补骨脂素加光诱导的含有链间交联的 DNA 修复。大肠杆菌已被研究。在补骨脂素加光处理后的 30 分钟孵育过程中，交联被切除，细胞 DNA 被切成离散的片段。这些片段的分子量相当于交联之间单链距离的大约两倍，通过碱性蔗糖中的沉降速度测量。在进一步孵育期间，这些 DNA 片段共价连接成高分子量 DNA。这种连接不会发生在携带 atrecA 突变的细胞中；在这些菌株中，DNA 进一步降解为更小的多核苷酸和酸溶性物质。研究了交联 DNA 修复涉及同源双链体之间链交换的可能性。细胞在含有 13 C、 15 N的培养基中生长几代，然后切换到还含有[ 3 H]胸苷的正常密度的培养基中约0.5代。交联处理后，将细胞在正常密度的培养基中孵育以进行修复。提取 DNA 并在碱性 CsCl 密度梯度中离心，轻链和重链被分离。含有 3 H的中等密度分子在野生型细胞的修复过程中积累，但在对照细胞或处理的recA细胞中则不然。中等密度DNA的分子量降低后，3H可以与重链分离，证明同源双链体的重链和轻链之间的共价连接伴随着修复。提出了一种涉及顺序切除和基因重组的机制来修复含有链间交联的 DNA。
The repair of DNA containing interstrand crosslinks induced by psoralen-plus-light inE. colicells has been investigated. During a 30-minute incubation after psoralen-plus-light treatment, crosslinks were excised and the cellular DNA was cut into discrete pieces. The molecular weight of these pieces corresponds to about twice the single-strand distance between crosslinks, as measured by sedimentation velocity in alkaline sucrose. During further incubation, these DNA fragments were covalently joined into high molecular weight DNA. This joining did not occur in cells carrying a mutation atrecA; in these strains the DNA was further degraded to smaller polynucleotides and acid-soluble material. The possibility that repair of crosslinked DNA involves strand exchanges between homologous duplexes was investigated. Cells were grown in13C,15N-containing medium for several generations, then switched to medium of normal density that also contained [3H]thymidine for about 0.5 generation. After the crosslinking treatment, the cells were incubated in medium of normal density in order for repair to occur. The DNA was extracted and centrifuged in alkaline CsCl density gradients, where the light and heavy strands were separated. Molecules of intermediate density that contained3H accumulated during repair in wild-type cells, but not in control cells or treatedrecA-cells. After molecular weight reduction of the intermediate-density DNA, the3H could be separated from the heavy strands, demonstrating that covalent joining between heavy and light strands of homologous duplexes accompanies repair. A mechanism involving sequential excision and genetic recombination is proposed for the repair of DNA containing interstrand crosslinks.