Ogata N, Miura T
Taiko Pharmaceutical Co., Ltd, Uchihonmachi 3-34-14, Suita, Osaka, Japan.
Nucleic Acids Res. 1998 Oct 15;26(20):4657-61. doi: 10.1093/nar/26.20.4657.
Genetic information encoded in a template of a genome is replicated in a complementary way by DNA polymerase or RNA polymerase with high fidelity; no creation of information occurs in this reaction unless an error occurs. We report here that DNA polymerase of the thermophilic bacterium Thermus thermophilus can synthesize up to 200 kb linear double-stranded DNA in vitro in the complete absence of added primer and template DNAs, indicating that genetic information is actively created by protein. This ab initio DNA synthesis occurs at 74 degrees C and requires magnesium ion. There is a lag time of approximately 1 h and then the reaction proceeds linearly. The synthesized DNAs have a variety of sequences; they are mostly tandem repetitive sequences, e.g. (CATGTATA) n , (TGTATGTATACATACATA) n and (TATACGTA) n . Some degenerate sequences of these basic repeat units are also found. The similar repetitive sequences are found in many natural genes. These results, together with similar results found using DNA polymerase of archaeon Thermococcus litoralis , suggest that creative, non-replicative synthesis of DNA by protein was a driving force for diversification of genetic information at a certain stage of the evolution of life on the early earth.
基因组模板中编码的遗传信息由DNA聚合酶或RNA聚合酶以互补方式进行高保真复制；除非发生错误，此反应中不会产生信息。我们在此报告，嗜热栖热菌的DNA聚合酶在完全不添加引物和模板DNA的情况下，可在体外合成长达200 kb的线性双链DNA，这表明遗传信息可由蛋白质主动产生。这种从头开始的DNA合成在74℃下进行，需要镁离子。有大约1小时的延迟期，然后反应呈线性进行。合成的DNA具有多种序列；它们大多是串联重复序列，例如(CATGTATA)n、(TGTATGTATACATACATA)n和(TATACGTA)n。还发现了这些基本重复单元的一些简并序列。在许多天然基因中也发现了类似的重复序列。这些结果，连同使用嗜热栖热放线菌的DNA聚合酶所发现的类似结果，表明蛋白质对DNA进行创造性的、非复制性的合成是早期地球上生命进化某一阶段遗传信息多样化的驱动力。
