改变蛋白质-DNA相互作用在复制起源许可期间促进ORC结合位点交换.
Annie Zhang1,2, Larry J Friedman3, Jeff Gelles3
1HHMI, Cambridge, MA 02139.
概括
原始识别复合体 (ORC) 通过切换结合点来加载两个Mcm2-7,用于通过切换结合点来进行DNA复制. DNA 不曲和滑动有助于ORC释放,使得序列酶加载和双向复制成为可能.
科学领域:
- 分子生物学分子生物学
- 生物化学 生物化学
- 遗传学 遗传学 是一个
背景情况:
- 细胞DNA复制的启动需要Mcm2-7酶,由起源识别复合体 (ORC) 负载.
- 为了实现双向复制,ORC连续加载两个Mcm2-7六元体,以头对头的方向向原始源.
- 为了实现这种顺序加载,ORC必须从高亲和度转移到低亲和度DNA结合位,但机制尚不清楚.
研究的目的:
- 阐明ORC在Mcm2-7酶的顺序加载过程中切换DNA结合位的机制.
- 在原产地许可期间调查DNA,ORC和Mcm2-7之间的动态相互作用.
主要方法:
- 单分子福斯特共振能量转移 (smFRET) 用于监测DNA-蛋白相互作用.
- 研究的重点是加载过程中DNA和ORC或Mcm2-7之间的相互作用变化.
主要成果:
- 在Mcm2-7沉积过程中DNA曲的损失加速了ORC与DNA的解离.
- 观察到包括ORC,Mcm2-7,Cdt1在内的中间复合物的临时控制的DNA滑动.
- 序列DNA解曲,Cdc6释放和DNA滑动逐渐降低ORC的DNA结合稳定性,促进位点切换.
结论:
- 动态蛋白-DNA相互作用,包括DNA不曲和滑动,对于ORC介导的Mcm2-7螺旋酶的顺序加载至关重要.
- 这种机制确保了螺旋酶的正确头对头对齐,以实现高效的双向DNA复制.
- 观察到的受控滑动提供了关于ORC如何访问二次DNA结合部位的见解.
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