Solaro P C, Birkenkamp K, Pfeiffer P, Kemper B
Institute for Genetics, University of Cologne, Köln, Germany.
J Mol Biol. 1993 Apr 5;230(3):868-77. doi: 10.1006/jmbi.1993.1207.
The reactivity of endonuclease VII (gp49 of phage T4) with DNA-loops of eight, four, or one nucleotide, or any of 12 possible base mismatches was tested in vitro. Endonuclease VII introduces double-strand breaks by nick and counter-nick within six nucleotides 3' from the mispairings. High relative cleavage efficiencies at mismatches in heteroduplexes correlate with their decreased thermal stability and vice versa. A delay between nick and counter-nick was sufficient to allow T4 DNA-polymerase and T4 DNA-ligase to correct a C/C-mismatch in vitro, thereby saving the DNA from double-strand breakage. Very short repair tracks of three to four nucleotides mapped between the mismatch and one of the formerly induced nicks, which were subsequently sealed by DNA ligase.
在体外测试了核酸内切酶VII（噬菌体T4的gp49）与八个、四个或一个核苷酸的DNA环或12种可能的碱基错配中的任何一种的反应性。核酸内切酶VII通过在错配3'端的六个核苷酸内的切口和反向切口引入双链断裂。异源双链体中错配处的相对高切割效率与其降低的热稳定性相关，反之亦然。切口和反向切口之间的延迟足以使T4 DNA聚合酶和T4 DNA连接酶在体外纠正C/C错配，从而使DNA免于双链断裂。在错配和先前诱导的一个切口之间定位了三到四个核苷酸的非常短的修复片段，随后由DNA连接酶封闭。
