RecA protein filaments: End-dependent dissociation from ssDNA and stabilization by RecO and RecR proteins
RecA protein filaments: End-dependent dissociation from ssDNA and stabilization by RecO and RecR proteins
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DOI：
10.1006/jmbi.1996.0748
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发表时间：
1997-02-07
影响因子：
5.6
通讯作者：
Cox, MM
中科院分区：
文献类型：
--
作者：
Shan, Q;Bork, JM;Cox, MM
只要ATP再生，在ssDNA结合蛋白（SSB）存在下在环状（ssDNA）上形成的RecA蛋白丝通常是稳定的。在线性ssDNA上，稳定的RecA细丝被认为是通过在DNA上的随机位点处成核，然后在5'至3'方向上的细丝延伸而形成的。这个观点现在必须被放大，因为我们证明了线性ssDNA上形成的RecA细丝受到以前未检测到的末端依赖性解体过程的影响。RecA蛋白从一个纤维末端缓慢解离并被SSB取代。结果与从最接近DNA的5'端的细丝端的解链最一致。结合的SSB阻止RecA细丝的重新形成，使得解离在很大程度上不可逆。解离需要ATP水解。当pH降低至6.3或当dATP取代ATP时，未观察到酶。当RecO和RecR蛋白质都存在于初始反应混合物中时，即使用ATP也没有观察到酶。当RecO和RecR蛋白在大部分RecA蛋白已经解离后加入时，RecA蛋白丝在短暂延迟后重新形成。新形成的细丝含有一定量的RecA蛋白，并且表现出与在初始反应混合物中包括RecO和RecR蛋白时观察到的ATP水解速率相当的ATP水解速率。因此，RecO和RecR蛋白甚至在ssDNA的5'端稳定RecA丝，这一事实应该影响5'端相对于3'端的重组潜力。重组DNA修复中涉及的RecA细丝的位置和长度由组装和拆卸过程以及可以调节任一过程的各种其他蛋白质的存在或不存在决定。(C)出版社：Academic Press Limited。
RecA protein filaments formed on circular (ssDNA) in the presence of ssDNA binding protein (SSB) are generally stable as long as ATP is regenerated. On linear ssDNA, stable RecA filaments are believed to be formed by nucleation at random sites on the DNA followed by filament extension in the 5' to 3' direction. This view must now be enlarged as we demonstrate that RecA filaments formed on linear ssDNA are subject to a previously undetected end-dependent disassembly process. RecA protein slowly dissociates from one filament end and is replaced by SSB. The results are most consistent with disassembly from the filament end nearest the 5' end of the DNA. The bound SSB prevents re-formation of the RecA filaments, rendering the dissociation largely irreversible. The dissociation requires ATP hydrolysis. Disassembly is not observed when the pH is lowered to 6.3 or when dATP replaces ATP. Disassembly is not observed even with ATP when both the RecO and RecR proteins are present in the initial reaction mixture. When the RecO and RecR proteins are added after most of the RecA protein has already dissociated, RecA protein filaments re-form after a short lag. The newly formed filaments contain an amount of RecA protein and exhibit an ATP hydrolysis rate comparable to that observed when the RecO and RecR proteins are included in the initial reaction mixture. The RecO and RecR proteins thereby stabilize RecA filaments even at the 5' ends of ssDNA, a fact which should affect the recombination potential of 5' ends relative to 3' ends. The location and length of RecA filaments involved in recombinational DNA repair is dictated by both the assembly and disassembly processes, as well as by the presence or absence of a variety of other proteins that can modulate either process. (C) 1997 Academic Press Limited.