LIGATION OF OLIGONUCLEOTIDES BY PYRIMIDINE DIMERS - A MISSING LINK IN THE ORIGIN OF LIFE
LIGATION OF OLIGONUCLEOTIDES BY PYRIMIDINE DIMERS - A MISSING LINK IN THE ORIGIN OF LIFE
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DOI：
10.1038/298393a0
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发表时间：
1982-01-01
期刊：
影响因子：
64.8
通讯作者：
HANAWALT, PC
中科院分区：
文献类型：
--
作者：
LEWIS, RJ;HANAWALT, PC
DNA暴露于UV时的主要光化学反应之一是形成链内环丁烷型嘧啶二聚体1，2。该反应的效率取决于UV 2的波长和DNA中的特定核苷酸序列。嘧啶二聚体的形成及其在活细胞中的修复已被广泛研究4。我们已经研究了这样一种可能性，即DNA链末端的嘧啶可以通过互补链的存在而充分并置以形成二聚体，即使没有磷酸二酯键连接它们的糖。在这些条件下，二聚体的形成将“连接”两条DNA链端对端。我们在这里报告，胸腺嘧啶寡核苷酸退火聚脱氧腺苷酸可以连接端到端的紫外线照射，通过胸腺嘧啶二聚化的末端核苷酸在相邻的寡核苷酸。的联系是易于直接光逆转254 nm紫外线，预期环丁烷型胸腺嘧啶二聚体，但它们不裂解的噬菌体T4核酸内切酶V，二聚体特异性DNA修复酶。我们证明，连接二聚体也耐光裂合酶从大肠杆菌。虽然磷酸二酯骨架不是二聚体形成所必需的，但它是这些DNA修复酶识别二聚体所必需的。我们讨论的可能性，高分子量的多核苷酸在原始海洋中可能已经产生的寡核苷酸的嘧啶二聚化下强烈的太阳紫外线通量未衰减的臭氧层。
One of the principal photochemical reactions of DNA on exposure to UV is the formation of intrastrand cyclobutane-type pyrimidine dimmers1,2. The efficiency of this reaction depends on both the wavelength of the UV2and the specific nucleotide sequence in the DNA3. The formation of the pyrimidine dimer and its repair in living cells have been studied extensively4. We have examined the possibility that pyrimidines at the ends of DNA strands may be adequately juxtaposed for dimer formation by the presence of a complementary strand, even when no phosphodiester linkage joins their sugars. In these conditions the formation of a dimer will ‘ligate’ two DNA strands end-to-end. We report here that thymidine oligonucleotides annealed to polydeoxyadenylate can be ligated end-to-end by UV irradiation, via thymine dimerization of the terminal nucleotides in adjacent oligonucleotides. The linkages are susceptible to direct photoreversal by 254 nm UV, as expected for cyclobutane-type thymine dimers, but they are not cleaved by the bacteriophage T4 endonuclease V, a dimer-specific DNA repair enzyme. We demonstrate that the ligating dimers are also resistant to photolyase fromEscherichia coli. Although the phosphodiester backbone is not required for dimer formation, it is required for recognition of dimers by these DNA repair enzymes. We discuss the possibility that high molecular weight polynucleotides in primordial seas might have been generated from oligonucleotides by pyrimidine dimerization under the intense solar UV flux unattenuated by an ozone layer.