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Mechanisms of metal ion action in tn10 transposition.

机译:tn10转座中金属离子作用的机制。

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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 (Me(2+)). Transpososome assembly and structure are also affected by Me(2+). To gain further insight into the mechanisms of Me(2+) action in Tn10/IS10 transposition we have investigated the effects of substituting Mn(2+) for Mg(2+), the physiologic Me(2+), in transposition. We have also investigated the significance of an Me(2+)-assisted conformational change in transpososome structure. We show that Mn(2+) 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. Mn(2+) also relaxes the specificity of first strand nicking. We also show that Me(2+)-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.
机译: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,然后在每个转座子末端进行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(Me(2+))的存在。转座体的组装和结构也受Me(2+)的影响。为了进一步了解Me(2+)在Tn10 / IS10换位中的作用机理,我们研究了用Mn(2+)代替Mg(2+),生理性Me(2+)换位的作用。我们还研究了转座体结构中Me(2+)辅助构象变化的重要性。我们显示Mn(2+)对Tn10供体的裂解反应有两个以前无法识别的影响。它可加快发夹形成和发夹分离的速率,而不会显着影响第一步化学步骤(第一条链切口)的速率。 Mn(2+)还可以放松第一条链切口的特异性。我们还显示,Me(2+)辅助转座子的展开与转座子-供体连接中的结构转变(可能对发夹的形成可能是一致的)相吻合。考虑了这些观察的可能机制。 (c)2002爱思唯尔科学有限公司。

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