Structural insight into replicative helicase loading in Escherichia coli
Structural insight into replicative helicase loading in Escherichia coli
复制标题
大肠杆菌复制解旋酶负载的结构洞察
DOI：
10.1093/jb/mvac023
复制
发表时间：
2022
期刊：
影响因子：
--
通讯作者：
Kurumizaka Hitoshi
中科院分区：
文献类型：
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作者：
Horikoshi Naoki;Kurumizaka Hitoshi
DNA复制是一个重要的，精确调节的过程，在细胞周期中发生一次。在革兰氏阴性菌大肠杆菌中，复制性解旋酶EcDnaB和解旋酶装载器EcDnaC在复制起点oriC的起始步骤中起关键作用，EcDnaB和EcDnaC形成异十二聚体，其中六聚体EcDnaB结合六聚体EcDnaC。使用遗传、生物化学和结构生物学方法，许多研究小组已经使用来自各种物种的解旋酶和解旋酶加载剂来探索复制解旋酶加载的机制。最近的X射线晶体学和低温电子显微镜（cryo-EM）的theEcDnaB-EcDnaC复合物的结构研究表明，DnaC与DnaB的相互作用触发的六聚体DnaB的闭环上的畸变积累，诱导DnaB亚基采取开放的螺旋形式的复制进展。Nagataet al解决的DnaB-DnaC复合物的高分辨率晶体结构有助于更好地理解DnaB环的构象重排。除了通过DnaC改变DnaB亚基的结构外，单链DNA（ssDNA）底物的结合改变了DnaB和DnaC的ATP和ADP结合形式。这些研究提出了DnaC调节解旋酶加载到ssDNA上的机制。
DNA replication is an essential, precisely regulated process that occurs once in a cell cycle. In the Gram-negative bacteriumEscherichia coli, the replicative helicaseEcDnaB and the helicase loaderEcDnaC play key roles in the initiation step at the replication origin,oriC.EcDnaB andEcDnaC form a heterododecamer, in which hexamericEcDnaB is bound to hexamericEcDnaC. Using genetic, biochemical and structural biology approaches, many groups have probed the mechanism of replicative helicase loading, using helicases and helicase loaders from various species. Recent X-ray crystallography and cryogenic electron microscopy (cryo-EM) structural studies of theEcDnaB–EcDnaC complex revealed that the interaction of DnaC with DnaB triggers distortion accumulation on the closed ring of hexameric DnaB, inducing DnaB subunits to adopt the open helical form for replication progression. The high-resolution crystal structure of the DnaB–DnaC complex solved by Nagataet al.contributed to a better understanding of the conformational rearrangement of the DnaB ring. In addition to the structural alterations in DnaB subunits by DnaC, the binding of single-stranded DNA (ssDNA) substrates alters the ATP- and ADP-bound forms of DnaB and DnaC. These studies have proposed mechanisms by which DnaC regulates helicase loading onto ssDNA.