Laboratoire de Microbiologie et Génétique Moléculaires, Centre National de Recherche Scientifique, Unité Mixte de Recherche 5100, 118 Route de Narbonne, F31062 Toulouse Cedex, France.
Cell. 2010 Aug 6;142(3):398-408. doi: 10.1016/j.cell.2010.06.034.
DNA transposition has contributed significantly to evolution of eukaryotes and prokaryotes. Insertion sequences (ISs) are the simplest prokaryotic transposons and are divided into families on the basis of their organization and transposition mechanism. Here, we describe a link between transposition of IS608 and ISDra2, both members of the IS200/IS605 family, which uses obligatory single-stranded DNA intermediates, and the host replication fork. Replication direction through the IS plays a crucial role in excision: activity is maximal when the "top" IS strand is located on the lagging-strand template. Excision is stimulated upon transient inactivation of replicative helicase function or inhibition of Okazaki fragment synthesis. IS608 insertions also exhibit an orientation preference for the lagging-strand template and insertion can be specifically directed to stalled replication forks. An in silico genomic approach provides evidence that dissemination of other IS200/IS605 family members is also linked to host replication.
DNA 转座对真核生物和原核生物的进化做出了重大贡献。插入序列 (ISs) 是最简单的原核转座子，根据其组织和转座机制分为不同的家族。在这里，我们描述了 IS608 和 ISDra2 之间的联系，它们都是 IS200/IS605 家族的成员，利用必需的单链 DNA 中间体和宿主复制叉。通过 IS 的复制方向在切除中起着至关重要的作用：当“顶部”IS 链位于滞后链模板上时，活性最大。复制解旋酶功能短暂失活或冈崎片段合成抑制会刺激切除。IS608 插入也表现出对滞后链模板的取向偏好，并且可以将插入物特异性地导向停滞的复制叉。一种计算机基因组学方法提供了证据，表明其他 IS200/IS605 家族成员的传播也与宿主复制有关。
