Structure and dynamics of the chromatin remodeler ALC1 bound to a PARylated nucleosome.
Structure and dynamics of the chromatin remodeler ALC1 bound to a PARylated nucleosome.
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DOI：
10.7554/elife.71420
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发表时间：
2021-09-06
期刊：
影响因子：
7.7
通讯作者：
Deindl S
中科院分区：
文献类型：
--
作者：
Bacic L;Gaullier G;Sabantsev A;Lehmann LC;Brackmann K;Dimakou D;Halic M;Hewitt G;Boulton SJ;Deindl S
染色质重构体ALC1在检测到DNA损伤时被PARP1/PARP2/HPF1沉积的DNA损伤诱导的聚(ADP-核糖)链激活。ALC1已成为癌症治疗的候选药物靶点，因为它的丢失使同源重组缺陷细胞的合成致死。然而，ALC1的基于结构的药物设计和分子分析一直受到PAR化要求和这种翻译后修饰的高度异质性的阻碍。在这里，我们用PARP2和HPF1重组了体外修饰的ALC1和PAR化核小体复合体。该络合物无需交联键即可进行冷冻EM结构测定，从而能够显示从识别PARylated核小体到紧密结合和激活重构体的几种中间状态。核小体PAR化的功能生化分析强调了核小体表位对生产性重塑的重要性，并表明ALC1优先使核小体远离DNA断裂。
The chromatin remodeler ALC1 is recruited to and activated by DNA damage-induced poly(ADP-ribose) (PAR) chains deposited by PARP1/PARP2/HPF1 upon detection of DNA lesions. ALC1 has emerged as a candidate drug target for cancer therapy as its loss confers synthetic lethality in homologous recombination-deficient cells. However, structure-based drug design and molecular analysis of ALC1 have been hindered by the requirement for PARylation and the highly heterogeneous nature of this post-translational modification. Here, we reconstituted an ALC1 and PARylated nucleosome complex modified in vitro using PARP2 and HPF1. This complex was amenable to cryo-EM structure determination without cross-linking, which enabled visualization of several intermediate states of ALC1 from the recognition of the PARylated nucleosome to the tight binding and activation of the remodeler. Functional biochemical assays with PARylated nucleosomes highlight the importance of nucleosomal epitopes for productive remodeling and suggest that ALC1 preferentially slides nucleosomes away from DNA breaks.