DnaC traps DnaB as an open ring and remodels the domain that binds primase
DnaC traps DnaB as an open ring and remodels the domain that binds primase
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DOI：
10.1093/nar/gkv961
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发表时间：
2016-01-08
影响因子：
14.9
通讯作者：
Kaguni, Jon M.
中科院分区：
文献类型：
--
作者：
Chodavarapu, Sundari;Jones, A. Daniel;Kaguni, Jon M.
DNA 复制起点处的解旋酶加载通常需要 DNA 解旋酶和辅助蛋白之间的动态相互作用。在大肠杆菌中，DNA 解旋酶是 DnaB，DnaC 是其装载伙伴。我们使用氢/氘交换质谱法来解决 DnaB-DnaC 复合物形成作为解旋酶加载先决条件的重要性。我们的结果表明，DnaB 环打开和关闭，并且 DnaC N 末端附近的特定氨基酸与 DnaB C 末端结构域中的一个位点相互作用，将其捕获为开环。该事件与参与核苷酸结合的 DnaB 的 RecA 折叠以及 DnaC 的 AAA+ 结构域的构象变化相关。 DnaC 还会引起 DnaB N 端结构域中螺旋发夹的改变，可能会阻止该区域与引物酶相互作用。因此，DnaC 通过引物酶控制 DnaB 的访问。
Helicase loading at a DNA replication origin often requires the dynamic interactions between the DNA helicase and an accessory protein. In E. coli, the DNA helicase is DnaB and DnaC is its loading partner. We used the method of hydrogen/deuterium exchange mass spectrometry to address the importance of DnaB-DnaC complex formation as a prerequisite for helicase loading. Our results show that the DnaB ring opens and closes, and that specific amino acids near the N-terminus of DnaC interact with a site in DnaB's C-terminal domain to trap it as an open ring. This event correlates with conformational changes of the RecA fold of DnaB that is involved in nucleotide binding, and of the AAA+ domain of DnaC. DnaC also causes an alteration of the helical hairpins in the N-terminal domain of DnaB, presumably occluding this region from interacting with primase. Hence, DnaC controls the access of DnaB by primase.