A minimal system for Tn7 transposition: The transposon-encoded proteins TnsA and TnsB can execute DNA breakage and joining reactions that generate circularized Tn7 species
A minimal system for Tn7 transposition: The transposon-encoded proteins TnsA and TnsB can execute DNA breakage and joining reactions that generate circularized Tn7 species
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DOI：
10.1006/jmbi.2000.3558
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发表时间：
2000-03-17
影响因子：
5.6
通讯作者：
Craig, NL
中科院分区：
文献类型：
--
作者：
Biery, MC;Lopata, M;Craig, NL
在ATP和Mg 2+存在下，细菌转座子Tn 7通过由转座子编码的蛋白质TnsA + TnsB + TnsC + TnsD执行的剪切和粘贴机制易位。本文报道了在Mn ~（2+）存在下，TnsA + TnsB可以单独进行Tn 7重组的DNA断裂和连接反应。ATP在这个最小系统中不是必需的，这表明这种辅因子并不直接参与重组的化学步骤。在TnsAB和TnsABC + D系统中，重组起始于每个转座子末端的双链断裂，该断裂将Tn 7从侧翼供体DNA中切割出来。在最小系统中，断裂主要发生在单个转座子末端，并且随后的末端连接反应是分子内的，断裂的转座子末端的暴露的3'末端在相同供体分子中的Tn 7元件的另一端附近连接以形成环状转座子种类。相反，在TnsABC + D重组中，断裂发生在Tn 7的两端，并且两端连接到不同DNA分子上的靶位点以形成分子间简单插入。TnsAB执行断裂和连接反应的能力的证明支持了这些蛋白质形成Tn 7转座酶的观点。(C)北京大学出版社.
In the presence of ATP and Mg2+, the bacterial transposon Tn7 translocates via a cut and paste mechanism executed by the transposon-encoded proteins TnsA + TnsB + TnsC + TnsD. We report here that in the presence of Mn2+, TnsA + TnsB alone can execute the DNA breakage and joining reactions of Tn7 recombination. ATP is not essential in this minimal system, revealing that this cofactor is not directly involved in the chemical steps of recombination. In both the TnsAB and TnsABC + D systems, recombination initiates with double-strand breaks at each transposon end that cut Tn7 away from flanking donor DNA. In the minimal system, breakage occurs predominantly at a single transposon end and the subsequent end-joining reactions are intramolecular, with the exposed 3' termini of a broken transposon end joining near the other end of the Tn7 element in the same donor molecule to form circular transposon species. In contrast, in TnsABC + D recombination, breaks occur at both ends of Tn7 and the two ends join to a target site on a different DNA molecule to form an intermolecular simple insertion. This demonstration of the capacity of TnsAB to execute breakage and joining reactions supports the view that these proteins form the Tn7 transposase. (C) 2000 Academic Press.