一个分子捕鼠器决定了大肠杆菌中DNA复制的终结极性
Mark D Mulcair1, Patrick M Schaeffer, Aaron J Oakley
1Research School of Chemistry, Australian National University, Canberra, ACT 0200, Australia.
Cell
|July 4, 2006
概括
大肠杆菌中的复制分叉被Tus蛋白在Ter位点阻止. 在允许端的线程分离释放Tus,允许分叉进展,而在不允许端的分离锁定Tus,阻止复制.
科学领域:
- 分子生物学分子生物学
- 遗传学 是一个遗传学.
- 生物化学 生物化学
背景情况:
- 在染色体合成过程中,DNA复制叉必须克服障碍.
- 在大肠杆菌中,与Ter位点结合的Tus蛋白质作为定向复制叉壁垒.
- 了解Tus介导终结的机制对于DNA复制调节至关重要.
研究的目的:
- 为了研究Tus介导的复制分叉极性在Ter站点的分子基础.
- 确定特定的DNA-蛋白相互作用在阻断或允许复制分叉进展中的作用.
- 阐明在不容许的Ter地点稳定复合体形成的基础结构机制.
主要方法:
- 从合成分叉的TerB寡核化物中测量Tus离合率.
- 在不同的链分离条件下对Tus-Tus-DNA复合体形成的分析.
- 锁定Tus-Ter复合体的晶体结构的确定.
主要成果:
- 在有限的线程分离时,Tus与TerB的允许端的快速解离.
- 在不允许端形成一个稳定的,锁定的Tus-Ter复合体,需要将链分离到保存的G-C(6) 基对.
- 位于位置6 (C(6) 的细胞蛋白对锁形成至关重要,重新定位以结合Tus.
结论:
- Tus介导的复制终结的极性是由不同Ter位末端对DNA链分离的反应决定的.
- 不允许端的锁形成涉及与C(6) 的特定相互作用,稳定了Tus-DNA复合体.
- 结构洞察力揭示了C(6) 运动如何促进稳定的复合体,有效地阻止DnaB螺旋酶.
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