Ogata N, Miura T
Taiko Pharmaceutical Co., Ltd., Uchihonmachi 3-34-14, Suita, Osaka, Japan.
Biochem J. 1997 Jun 1;324 ( Pt 2)(Pt 2):667-71. doi: 10.1042/bj3240667.
DNA polymerase catalyses replication of cellular DNA. The reaction requires a primer-template complex, and a new DNA chain grows from the 3' end of the primer along the template; no genetic information is created in this reaction. We demonstrate that DNA polymerase from Thermococcus litoralis, a hyperthermophilic marine Archaea, can synthesize up to 50000 bp of linear double-stranded DNA in the complete absence of a primer-template complex, indicating that genetic information is 'created.' The possibility of DNA contamination in the reaction mixture, which may serve as a primer and/or template, was vigorously excluded; for example, pretreatment of DNA polymerase with DNase I or extensive chromatographic purification of the substrate, deoxyribonucleoside 5'-triphosphates, did not abolish the primer-template-independent DNA synthesis. The DNA synthesized was (CTAGATAT)n, (TAGATATCTATC)n or a related sequence. Similar repetitive sequences are found in centromeric satellite DNA of many organisms. The significance of this ab initio DNA synthesis is that genetic information can flow from protein to DNA.
DNA聚合酶催化细胞DNA的复制。该反应需要引物-模板复合物，新的DNA链从引物的3'端沿着模板生长；此反应中不会产生遗传信息。我们证明，来自嗜热栖热放线菌（一种嗜热海洋古菌）的DNA聚合酶，在完全没有引物-模板复合物的情况下，能够合成长达50000 bp的线性双链DNA，这表明遗传信息是“被创造出来的”。我们有力地排除了反应混合物中可能作为引物和/或模板的DNA污染的可能性；例如，用DNase I预处理DNA聚合酶或对底物脱氧核糖核苷5'-三磷酸进行广泛的色谱纯化，都不会消除不依赖引物-模板的DNA合成。合成的DNA是(CTAGATAT)n、(TAGATATCTATC)n或相关序列。在许多生物体的着丝粒卫星DNA中都发现了类似的重复序列。这种从头合成DNA的意义在于遗传信息可以从蛋白质流向DNA。
