Stasiak A
Laboratoire d'Analyse Ultrastructurale, Université de Lausanne, Bâtiment de Biologie, Switzerland.
Mol Microbiol. 1992 Nov;6(22):3267-76. doi: 10.1111/j.1365-2958.1992.tb02194.x.
A novel type of triple-stranded DNA structure was proposed by several groups to play a crucial role in homologous recognition between single- and double-stranded DNA molecules. In this still putative structure a duplex DNA was proposed to co-ordinate a homologous single strand in its major groove side. In contrast to the well-characterized pyrimidine-purine-pyrimidine triplexes in which the two like strands are antiparallel and which are restricted to poly-pyrimidine-containing stretches, the homology-specific triplexes would have like strands in parallel orientation and would not be restricted to any particular sequence provided that there is a homology between interacting DNA molecules. For many years the stereo-chemical possibility of forming homology-dependent three- or four-stranded DNA structures during the pairing stage of recombination reactions was seriously considered in published papers. However, only recently has there been a marked increase in the number of papers that have directly tested the formation of triple-stranded DNA structures during the actual pairing stage of the recombination reaction. Unfortunately the results of these tests are not totally clear cut; while some laboratories presented experimental evidence consistent with the formation of triplexes, others studying the same or very similar systems offered alternative explanations. The aim of this review is to present the current state of the central question in the mechanism of homologous recombination, namely, what kind of DNA structure is responsible for DNA homologous recognition. Is it a novel triplex structure or just a classical duplex?
几个研究小组提出了一种新型的三链DNA结构，认为它在单链和双链DNA分子之间的同源识别中起关键作用。在这种仍为假定的结构中，双链DNA被认为在其大沟侧协调一条同源单链。与特征明确的嘧啶-嘌呤-嘧啶三链体不同，其中两条相同的链是反平行的，并且仅限于含多嘧啶的片段，同源特异性三链体的相同链将呈平行排列，并且只要相互作用的DNA分子之间存在同源性，就不会局限于任何特定序列。多年来，在已发表的论文中，人们一直认真考虑在重组反应的配对阶段形成同源依赖性三链或四链DNA结构的立体化学可能性。然而，直到最近，直接测试重组反应实际配对阶段三链DNA结构形成的论文数量才显著增加。不幸的是，这些测试结果并不完全明确；虽然一些实验室提供了与三链体形成一致的实验证据，但其他研究相同或非常相似系统的实验室则给出了不同的解释。本综述的目的是介绍同源重组机制核心问题的当前状态，即什么样的DNA结构负责DNA同源识别。是一种新型的三链结构还是仅仅是经典的双链结构？
