Hanvey J C, Shimizu M, Wells R D
Department of Biochemistry, School of Medicine, University of Alabama, Birmingham 35294.
Proc Natl Acad Sci U S A. 1988 Sep;85(17):6292-6. doi: 10.1073/pnas.85.17.6292.
A series of inserts with oligopurine.oligopyrimidine mirror repeat sequences was investigated at the base pair level with specific chemical probes (OsO4 and diethylpyrocarbonate) to evaluate the in vitro existence of intramolecular triplexes. Two parent inserts in recombinant plasmids with (GAA)9 and (AG)12 sequences and three mutant inserts (containing transitions or transversions) revealed that base pair changes at one location affected the chemical reactivity 13 base pairs away. The specificity and nature of these reactions, as well as the thermal stability of the complexes, provide direct evidence for the existence of a triplex with a portion of the pyrimidine-rich strand folded back and Hoogsteen-paired in the major groove of the Watson-Crick duplex. The biological implications of this unorthodox DNA structure are discussed.
使用特定化学探针（四氧化锇和焦碳酸二乙酯）在碱基对水平研究了一系列带有寡聚嘌呤-寡聚嘧啶镜像重复序列的插入片段，以评估分子内三链体在体外的存在情况。两个含有（GAA）9和（AG）12序列的重组质粒中的亲本插入片段以及三个突变插入片段（包含转换或颠换）表明，一个位置的碱基对变化会影响13个碱基对以外的化学反应性。这些反应的特异性和性质以及复合物的热稳定性，为存在一种三链体提供了直接证据，该三链体中富含嘧啶的链的一部分向后折叠并在沃森-克里克双链体的大沟中形成Hoogsteen配对。讨论了这种非传统DNA结构的生物学意义。
