过渡状态的Arp2/3复合体激活由Actin-Bound Dimeric核化促进因子激活
Trevor van Eeuwen1, Malgorzata Boczkowska2, Grzegorz Rebowski2
1Biochemistry and Molecular Biophysics Graduate Group, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104.
概括
对于细胞运动至关重要的Arp2/3复合体,通过辅因子过渡到活性状态. 这项研究揭示了其中间结构,澄清了这些辅助因子如何协调分支性动因子网络的激活.
科学领域:
- 细胞生物学 细胞生物学
- 生物化学 生物化学
- 结构生物学 结构生物学
背景情况:
- 该Arp2/3复合体对于产生分支性actin网络至关重要,驱动关键的细胞过程,如运动性和细胞运动.
- 它由7种蛋白质组成,包括Arp2和Arp3,并在分支交叉处与现有的活性丝相互作用.
- Arp2/3 复合体存在于非活性 (端对端 Arp 相互作用) 和活性 (并排 Arp 相互作用) 形状,与 NPF 和 ATP 等辅因子影响这种过渡.
研究的目的:
- 阐明各种辅助因子在Arp2/3复合体激活中的精确贡献.
- 通过可视化一个过渡状态来确定Arp2/3复合体激活的结构基础.
- 了解激活辅因子在调节Arp2/3复合体构造和功能的协调作用.
主要方法:
- 使用冷电子显微镜 (cryo-EM) 确定了Arp2/3复合体在激活过渡状态中的结构.
- 一个组成的二维NPF,N-WASP,被设计并与CapZ合并以稳定该复合体.
- 结构分析的重点是过渡状态内的Arp2,Arp3和actin的构造.
主要成果:
- 获得了Arp2/3复合体的3.32 Å分辨率的冷电磁结构,该复合体处于与二维NPF结合的中间激活状态.
- 结构揭示了Arp2,Arp3和actin的中间构造,与单体和丝状状态不同,只有actin能化ATP.
- 与非活性复合体相比,过渡复合体表现出向活跃短波形状的动力转移,以及对母纤维的亲和力增加.
结论:
- 该研究提供了Arp2/3复合体激活的结构快照,揭示了其核心组件的中间形状.
- 它展示了NPF,actin单体和母丝结合如何共同促进Arp2/3复合体的激活.
- 这些发现澄清了各种辅助因子推动过渡到活跃的,分支的actin网络形成状态的协调机制.
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