In vitro chromatin remodelling by chromatin accessibility complex (CHRAC) at the SV40 origin of DNA replication
In vitro chromatin remodelling by chromatin accessibility complex (CHRAC) at the SV40 origin of DNA replication
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DOI：
10.1093/emboj/17.12.3428
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发表时间：
1998-06-15
期刊：
影响因子：
11.4
通讯作者：
Gruss, C
中科院分区：
文献类型：
--
作者：
Alexiadis, V;Varga-Weisz, PD;Gruss, C
DNA复制是通过起始因子与复制起点的结合而启动的。已知核小体抑制复制机器接近起始序列。最近，已鉴定出核小体重塑因子可增加核小体 DNA 与转录调节因子的可及性。为了测试从核小体覆盖的起点开始的 DNA 复制是否也会受益于核小体重塑因子的作用，我们将 SV40 DNA 重构为果蝇胚胎提取物中的染色质。在 T 抗原和 ATP 存在的情况下，染色质相关辅因子允许在体外从核小体起源进行有效复制。在寻找负责的能量依赖性辅因子时，我们发现纯化的“染色质可及性复合物”（CHRAC）能够改变起始点的核小体结构，从而允许 T 抗原的结合和有效的复制起始。这些实验为核小体重塑机器参与体外 DNA 复制 SV40 起点的结构变化提供了证据。
DNA replication is initiated by binding of initiation factors to the origin of replication. Nucleosomes are known to inhibit the access of the replication machinery to origin sequences. Recently, nucleosome remodelling factors have been identified that increase the accessibility of nucleosomal DNA to transcription regulators. To test whether the initiation of DNA replication from an origin covered by nucleosomes would also benefit from the action of nucleosome remodelling factors, we reconstituted SV40 DNA into chromatin in Drosophila embryo extracts. In the presence of T-antigen and ATP, a chromatin-associated cofactor allowed efficient replication from a nucleosomal origin irt vitro. In search of the energy-dependent cofactor responsible we found that purified 'chromatin accessibility complex' (CHRAC) was able to alter the nucleosomal structure at the origin allowing the binding of T-antigen and efficient initiation of replication. These experiments provide evidence for the involvement of a nucleosome remodelling machine in structural changes at the SV40 origin of DNA replication in vitro.