The left end of IS2: a compromise between transpositional activity and an essential promoter function that regulates the transposition pathway.
The left end of IS2: a compromise between transpositional activity and an essential promoter function that regulates the transposition pathway.
复制标题
IS2 的左端：转座活性和调节转座途径的基本启动子功能之间的折衷。
DOI：
10.1128/jb.186.3.858-865.2004
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发表时间：
2004
影响因子：
3.2
通讯作者：
Grindley,NigelDF
中科院分区：
文献类型：
--
作者：
Lewis,LeslieA;Cylin,Edruge;Lee,HoKyung;Saby,Robert;Wong,Wilson;Grindley,NigelDF
剪切-粘贴（简单插入）和复制转座途径是转座因子被动员的两种经典范式。is3家族的插入序列最近提出了一种新的剪切和粘贴方法，即两步转位循环。在is2中，这种变异包括在第一步形成一个圆形，假定的转位中间体（小圆）。小圈子的两个方面可能涉及其在第二步（融入目标）中拟议的作用。首先是由元件的两个相邻端形成的高反应性结的存在。第二种是在一个强杂交启动子的小圆连接处的组装，它产生更高水平的转座酶。在本报告中，我们发现is2具有一个高度活性的小环结，在这个结上组装了一个强启动子，并且该启动子是有效完成该途径所必需的。我们表明，序列转移的特征是该元件的不完美的反向重复或末端已经进化，以允许该启动子的形成和最佳功能。虽然这些序列转移消除了线性元件左端（IRL）的催化活性，但在微环连接的背景下，IRL保留了催化所必需的足够的序列信息。这些数据证实，在IS2的两步转位途径中，迷你环是必不可少的中间物。
Cut-and-paste (simple insertion) and replicative transposition pathways are the two classical paradigms by which transposable elements are mobilized. A novel variation of cut and paste, a two-step transposition cycle, has recently been proposed for insertion sequences of the IS3family. In IS2this variation involves the formation of a circular, putative transposition intermediate (the minicircle) in the first step. Two aspects of the minicircle may involve its proposed role in the second step (integration into the target). The first is the presence of a highly reactive junction formed by the two abutted ends of the element. The second is the assembly at the minicircle junction of a strong hybrid promoter which generates higher levels of transposase. In this report we show that IS2possesses a highly reactive minicircle junction at which a strong promoter is assembled and that the promoter is needed for the efficient completion of the pathway. We show that the sequence diversions which characterize the imperfect inverted repeats or ends of this element have evolved specifically to permit the formation and optimal function of this promoter. While these sequence diversions eliminate catalytic activity of the left end (IRL) in the linear element, sufficient sequence information essential for catalysis is retained by the IRL in the context of the minicircle junction. These data confirm that the minicircle is an essential intermediate in the two-step transposition pathway of IS2.