Folding of cohesin's coiled coil is important for Scc2/4-induced association with chromosomes.
Folding of cohesin's coiled coil is important for Scc2/4-induced association with chromosomes.
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DOI：
10.7554/elife.67268
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发表时间：
2021-07-14
期刊：
影响因子：
7.7
通讯作者：
Nasmyth KA
中科院分区：
文献类型：
--
作者：
Petela NJ;Gonzalez Llamazares A;Dixon S;Hu B;Lee BG;Metson J;Seo H;Ferrer-Harding A;Voulgaris M;Gligoris T;Collier J;Oh BH;Löwe J;Nasmyth KA
粘着蛋白与染色体DNA的结合和沿着染色体DNA的易位依赖于ATP水解循环，ATP水解循环驱动DNA的结合和随后的释放。这涉及DNA被Scc 2和粘附素Smc 1和Smc 3头部结构域的ATP依赖性接合“夹紧”。Scc 2被Pds 5取代，消除了粘附蛋白的ATP酶，并在停止DNA环挤出中起重要作用。所有SMC蛋白的ATP酶结构域通过50 nm长的卷曲螺旋与它们的铰链二聚化结构域分开，已经观察到所述卷曲螺旋沿着它们的整个长度拉上沿着并围绕肘部折叠，从而大大缩短铰链和ATP酶头之间的距离。折叠是否存在于体内或具有任何生理重要性尚不清楚。我们在这里提出了一个cryo-EM结构的载脂蛋白形式的凝聚素，揭示了结构的折叠和拉链线圈在前所未有的细节，并表明Scc 2可以与Smc 1的ATP酶头，即使它是完全脱离Smc 3。使用半胱氨酸特异性交联，我们表明，凝聚素的卷曲螺旋经常折叠在体内，包括当凝聚素举行姐妹染色单体在一起。此外，我们描述了Smc 1的铰链内的突变（SMC 1D 588 Y），改变了Scc 2和Pds 5如何与Smc 1的铰链相互作用，使Scc 2能够在没有其正常的合作伙伴Scc 4的情况下支持加载。没有Scc 4的加载的突变表型只有在加载依赖于Scc 2/4和粘附素铰链之间的关联时才是可解释的，这反过来又需要卷曲螺旋折叠。
Cohesin’s association with and translocation along chromosomal DNAs depend on an ATP hydrolysis cycle driving the association and subsequent release of DNA. This involves DNA being ‘clamped’ by Scc2 and ATP-dependent engagement of cohesin’s Smc1 and Smc3 head domains. Scc2’s replacement by Pds5 abrogates cohesin’s ATPase and has an important role in halting DNA loop extrusion. The ATPase domains of all SMC proteins are separated from their hinge dimerisation domains by 50-nm-long coiled coils, which have been observed to zip up along their entire length and fold around an elbow, thereby greatly shortening the distance between hinges and ATPase heads. Whether folding exists in vivo or has any physiological importance is not known. We present here a cryo-EM structure of the apo form of cohesin that reveals the structure of folded and zipped-up coils in unprecedented detail and shows that Scc2 can associate with Smc1’s ATPase head even when it is fully disengaged from that of Smc3. Using cysteine-specific crosslinking, we show that cohesin’s coiled coils are frequently folded in vivo, including when cohesin holds sister chromatids together. Moreover, we describe a mutation (SMC1D588Y) within Smc1’s hinge that alters how Scc2 and Pds5 interact with Smc1’s hinge and that enables Scc2 to support loading in the absence of its normal partner Scc4. The mutant phenotype of loading without Scc4 is only explicable if loading depends on an association between Scc2/4 and cohesin’s hinge, which in turn requires coiled coil folding.