The origin recognition complex requires chromatin tethering by a hypervariable intrinsically disordered region that is functionally conserved from sponge to man
The origin recognition complex requires chromatin tethering by a hypervariable intrinsically disordered region that is functionally conserved from sponge to man
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DOI：
10.1093/nar/gkae122
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发表时间：
2024-02-21
影响因子：
14.9
通讯作者：
Parker，Matthew W.
中科院分区：
文献类型：
--
作者：
Adiji，Olubu A.;McConnell，Brendan S.;Parker，Matthew W.
真核生物基因组复制的第一步是将复制性解旋酶装载到染色质上。这个“许可”步骤起始于将起始识别复合物（ORC）募集到染色质，这被认为是通过ORC的ATP依赖性DNA结合和包围活性发生的。然而，我们以前已经表明，ATP结合是不稳定的染色质招聘飞ORC，提出的问题，如何后生动物ORC结合染色体。我们在这里表明，固有的无序区（IDR）的苍蝇Orc1是必要的和足够的招募ORC的染色体在vivoand证明，这是受IDR磷酸化。因此，我们发现IDR使ORC全复合物在体外具有ATP非依赖性的DNA结合活性。使用系统发育分析，我们令人惊讶的观察，后生动物Orc1 IDRs分歧如此显着，他们是无法识别的直系同源物，但我们发现，这些组成同源序列是功能保守的。总而言之，这些数据表明，染色质对ORC的ATP依赖性DNA结合活性是不稳定的，需要IDR依赖性染色质束缚，我们建议使ORC在无核小体区域可用时机会性地包围它们。
The first step toward eukaryotic genome duplication is loading of the replicative helicase onto chromatin. This ‘licensing’ step initiates with the recruitment of the origin recognition complex (ORC) to chromatin, which is thought to occur via ORC’s ATP-dependent DNA binding and encirclement activity. However, we have previously shown that ATP binding is dispensable for the chromatin recruitment of fly ORC, raising the question of how metazoan ORC binds chromosomes. We show here that the intrinsically disordered region (IDR) of fly Orc1 is both necessary and sufficient for recruitment of ORC to chromosomesin vivoand demonstrate that this is regulated by IDR phosphorylation. Consistently, we find that the IDR confers the ORC holocomplex with ATP-independent DNA binding activityin vitro. Using phylogenetic analysis, we make the surprising observation that metazoan Orc1 IDRs have diverged so markedly that they are unrecognizable as orthologs and yet we find that these compositionally homologous sequences are functionally conserved. Altogether, these data suggest that chromatin is recalcitrant to ORC’s ATP-dependent DNA binding activity, necessitating IDR-dependent chromatin tethering, which we propose poises ORC to opportunistically encircle nucleosome-free regions as they become available.