Mechanisms of metal ion action in Tn10 transposition
Mechanisms of metal ion action in Tn10 transposition
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DOI：
10.1016/s0022-2836(02)00297-8
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发表时间：
2002-05-24
影响因子：
5.6
通讯作者：
Haniford, DB
中科院分区：
文献类型：
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作者：
Allingham, JS;Haniford, DB
Tn10/IS10转座涉及突触复合体(或转座体)的组装，其中两个转座子末端配对，随后在每个转座子末端经历四个不同的化学步骤。化学步骤取决于合适的二价金属阳离子(Me2+)的存在。转座体的组装和结构也受到Me2+的影响。为了进一步了解Me~(2+)在Tn10/IS10转座中的作用机制，我们研究了在转座过程中用Mn2+替代生理Me~(2+)的效果。我们还研究了Me~(2+)辅助的转座体结构构象变化的意义。我们发现，Mn2+对Tn10施主的切割反应有两个以前未被认识到的作用。它加快了发夹形成和发夹分辨的速度，而不显著影响第一化学步骤、第一链划痕的速度。Mn2+也放松了第一链划痕的特异性。我们还表明，Me2+辅助的转座体展开与转座子-供体连接中的结构转变相吻合，这可能是发夹形成所必需的。考虑了这些观察的可能机制。(C)2002爱思唯尔科学有限公司。保留所有权利。
Tn10/IS10 transposition involves assembly of a synaptic complex (or transpososome) in which two transposon ends are paired, followed by four distinct chemical steps at each transposon end. The chemical steps are dependent on the presence of a suitable divalent metal cation (Me2+). Transpososome assembly and structure are also affected by Me2+. To gain further insight into the mechanisms of Me2+ action in Tn10/IS10 transposition we have investigated the effects of substituting Mn2+ for Mg2+, the physiologic Me2+, in transposition. We have also investigated the significance of an Me2+-assisted conformational change in transpososome structure. We show that Mn2+ has two previously unrecognized effects on the Tn10 donor cleavage reaction. It accelerates the rates of hairpin formation and hairpin resolution without significantly affecting the rate of the first chemical step, first strand nicking. Mn2+ also relaxes the specificity of first strand nicking. We also show that Me2+-assisted transpososome unfolding coincides with a structural transition in the transposon-donor junction that may be necessary for hairpin formation. Possible mechanisms for these observations are considered. (C) 2002 Elsevier Science Ltd. All rights reserved.