Ogata N, Miura T
Taiko Pharmaceutical Co., Ltd, Uchihonmachi 3-34-14, Suita, Osaka, Japan.
Nucleic Acids Res. 1998 Oct 15;26(20):4652-6. doi: 10.1093/nar/26.20.4652.
DNA polymerase of the archaeon Thermococcus litoralis can synthesize a long stretch of linear double-stranded DNA in the complete absence of added primer and template DNAs. This finding suggests that genetic information can potentially be created by protein. We report here the effects of temperature, ionic strength and pH on this ab initio DNA synthesis by the protein in vitro . When the temperature of the reaction was changed, the sequence of the product DNA changed markedly. For instance, the reaction products were (TAAT) n at 69 degrees C, (TATCCGGA) n at 84 degrees C and (TATCGCGATAGCGATCGC) n at 89 degrees C. The ionic strength of the reaction condition also affected the sequence: it was (TATCTAGA) n with 0 mM KCl, (TATATACG) n with 50 mM KCl and (TATAGTTATAAC) n with 100 mM KCl at 74 degrees C. When the pH of the reaction condition was changed from 6.8 to 10.8, the size of the product DNA decreased, but its sequence did not. These results demonstrate that DNA synthesized ab initio by DNA polymerase of T.litoralis is markedly influenced by the reaction conditions. The results also suggest that genetic information that might have been created by protein on the early earth is strongly influenced by environmental factors.
嗜热栖热袍菌的DNA聚合酶能够在完全不添加引物和模板DNA的情况下合成一段很长的线性双链DNA。这一发现表明遗传信息有可能由蛋白质创造。我们在此报告温度、离子强度和pH对该蛋白质体外从头合成DNA的影响。当改变反应温度时，产物DNA的序列会发生显著变化。例如，在69℃时反应产物为(TAAT)n，在84℃时为(TATCCGGA)n，在89℃时为(TATCGCGATAGCGATCGC)n。反应条件的离子强度也会影响序列：在74℃时，0 mM KCl条件下产物为(TATCTAGA)n，50 mM KCl条件下为(TATATACG)n，100 mM KCl条件下为(TATAGTTATAAC)n。当反应条件的pH从6.8变为10.8时，产物DNA的大小会减小，但其序列不变。这些结果表明，嗜热栖热袍菌DNA聚合酶从头合成的DNA受到反应条件的显著影响。这些结果还表明，早期地球上可能由蛋白质创造的遗传信息受到环境因素的强烈影响。
