Müller B, Jones C, West S C
Imperial Cancer Research Fund, Clare Hall Laboratories, South Mimms, Herts, UK.
Nucleic Acids Res. 1990 Oct 11;18(19):5633-6. doi: 10.1093/nar/18.19.5633.
T7 endonuclease I is known to bind and cleave four-way junctions in DNA. Since these junctions serve as analogues of Holliday junctions that arise during genetic recombination, we have investigated the action of T7 endonuclease I on recombination intermediates containing Holliday junctions. We find that addition of T7 endonuclease I to strand exchange reactions catalysed by RecA protein of Escherichia coli leads to the formation of duplex products that correspond to 'patch' and 'splice' type recombinants. Resolution of the recombination intermediates occurs by the introduction of nicks at the site of the Holliday junction. The recombinant molecules contain 5'-phosphate and 3'-hydroxyl termini which may be ligated to restore the integrity of the DNA.
已知T7核酸内切酶I能结合并切割DNA中的四链连接体。由于这些连接体可作为遗传重组过程中出现的霍利迪连接体的类似物，我们研究了T7核酸内切酶I对含有霍利迪连接体的重组中间体的作用。我们发现，向大肠杆菌RecA蛋白催化的链交换反应中添加T7核酸内切酶I会导致形成对应于“补丁”型和“拼接”型重组体的双链产物。重组中间体的拆分是通过在霍利迪连接体部位引入切口来实现的。重组分子含有5'-磷酸和3'-羟基末端，可通过连接来恢复DNA的完整性。
