Interactions of protein complexes on supercoiled DNA:: The mechanism of selective synapsis by Tn3 resolvase
Interactions of protein complexes on supercoiled DNA:: The mechanism of selective synapsis by Tn3 resolvase
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DOI：
10.1016/s0022-2836(02)00309-1
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发表时间：
2002-05-31
影响因子：
5.6
通讯作者：
Boocock, MR
中科院分区：
文献类型：
--
作者：
Brown, JL;He, JY;Boocock, MR
由 DNA 结合蛋白介导的 DNA 分子上远处位点的“循环”相互作用是许多受调控的遗传过程的特征。我们使用含有多达 6 个 Tn3 解离酶 res 重组位点的质粒来分析该系统中的循环相互作用（突触）。我们观察到，在具有四个或更多 res 位点的质粒中，某些位点对的重组速度比其他位点快。重组的相对速率取决于位点的数量、相对方向和排列。为了解释速率的差异，我们提出，解离酶结合的 res 位点之间的配对相互作用处于快速流动的状态，导致每个超螺旋底物分子内的最大数量的位点以拓扑简单的排列突触的配置。重组率反映了这些突触配置的稳态浓度。我们的结果与选择性突触模型不同，选择性突触依赖于超螺旋 DNA 内的有序运动、“滑行”或“跟踪”，但与要求通过随机碰撞实现位点对可逆突触、随后形成缠绕的生产性突触的模型兼容。 (C) 2002 Elsevier Science Ltd. 保留所有权利。
"Looping" interactions of distant sites on DNA molecules, mediated by DNA-binding proteins, feature in many regulated genetic processes. We used plasmids containing up to six res recombination sites for Tn3 resolvase to analyse looping interactions (synapsis) in this system. We observed that in plasmids with four or more res sites, certain pairs of sites recombine faster than others. The relative rates of recombination depend on the number, relative orientation, and arrangement of the sites. To account for the differences in rate, we propose that pairing interactions between resolvase-bound res sites are in a state of rapid flux, leading to configurations in which the maximum number of sites within each supercoiled substrate molecule are synapsed in a topologically simple arrangement. Recombination rates reflect the steady state concentrations of these synapse configurations. Our results are at variance with models for selective synapsis that rely on ordered motions within supercoiled DNA, "slithering" or "tracking", but are compatible with models that call for reversible synapsis of pairs of sites by random collision, followed by formation of an interwound productive synapse. (C) 2002 Elsevier Science Ltd. All rights reserved.