Real-time observation of RecA filament dynamics with single monomer resolution
Real-time observation of RecA filament dynamics with single monomer resolution
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DOI：
10.1016/j.cell.2006.06.042
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发表时间：
2006-08-11
期刊：
影响因子：
64.5
通讯作者：
Ha, Taekjip
中科院分区：
文献类型：
--
作者：
Joo, Chirlmin;McKinney, Sean A.;Ha, Taekjip
RecA及其同源物通过重组帮助维持基因组的完整性。使用单分子荧光检测和隐马尔可夫模型，我们显示了最直接的证据，RecA丝生长和收缩主要是一个单体的时间，只有在四肢。与预期相反，两端都生长和收缩，但一端的较高结合率是定向长丝生长的原因。定量速率测定还提供了关于RecA如何控制体内DNA可及性的见解。我们发现，大约五个单体是足够的长丝成核。虽然通常单链DNA结合蛋白（SSB）阻止细丝成核，但单个RecA单体可以容易地添加到现有的细丝中，并以细丝延伸的速率从DNA中置换SSB。这支持了RecA装载机在SSB清除中发挥被动作用的建议。
RecA and its homologs help maintain genomic integrity through recombination. Using singlemolecule fluorescence assays and hidden Markov modeling, we show the most direct evidence that a RecA filament grows and shrinks primarily one monomer at a time and only at the extremities. Both ends grow and shrink, contrary to expectation, but a higher binding rate at one end is responsible for directional filament growth. Quantitative rate determination also provides insights into how RecA might control DNA accessibility in vivo. We find that about five monomers are sufficient for filament nucleation. Although ordinarily single-stranded DNA binding protein (SSB) prevents filament nucleation, single RecA monomers can easily be added to an existing filament and displace SSB from DNA at the rate of filament extension. This supports the proposal for a passive role of RecA-loading machineries in SSB removal.