State Key Laboratory of Protein and Plant Gene Research, School of Life Sciences and Peking-Tsinghua Center for Life Sciences, Peking University, Beijing 100871, China.
Peking University-Tsinghua University-National Institute of Biological Sciences Joint Graduate Program, School of Life Sciences, Tsinghua University, Beijing 100084, China.
Science. 2017 Jan 27;355(6323):415-420. doi: 10.1126/science.aah4712.
DNA replication-coupled nucleosome assembly is essential to maintain genome integrity and retain epigenetic information. Multiple involved histone chaperones have been identified, but how nucleosome assembly is coupled to DNA replication remains elusive. Here we show that replication protein A (RPA), an essential replisome component that binds single-stranded DNA, has a role in replication-coupled nucleosome assembly. RPA directly binds free H3-H4. Assays using a synthetic sequence that mimics freshly unwound single-stranded DNA at replication fork showed that RPA promotes DNA-(H3-H4) complex formation immediately adjacent to double-stranded DNA. Further, an RPA mutant defective in H3-H4 binding exhibited attenuated nucleosome assembly on nascent chromatin. Thus, we propose that RPA functions as a platform for targeting histone deposition to replication fork, through which RPA couples nucleosome assembly with ongoing DNA replication.
DNA 复制偶联核小体组装对于维持基因组完整性和保留表观遗传信息至关重要。已经鉴定出多种涉及的组蛋白伴侣,但核小体组装如何与 DNA 复制偶联仍然难以捉摸。在这里,我们表明复制蛋白 A (RPA),一种结合单链 DNA 的必需复制体成分,在复制偶联核小体组装中起作用。RPA 直接结合游离的 H3-H4。使用模拟复制叉处新解开的单链 DNA 的合成序列进行的测定表明,RPA 促进紧邻双链 DNA 的 DNA-(H3-H4) 复合物形成。此外,在 H3-H4 结合中具有缺陷的 RPA 突变体在新生染色质上表现出减弱的核小体组装。因此,我们提出 RPA 作为将组蛋白沉积靶向复制叉的平台发挥作用,通过该平台,RPA 将核小体组装与正在进行的 DNA 复制偶联。