NMR structure of the N-terminal domain of E-coli DnaB helicase:: implications for structure rearrangements in the helicase hexamer
NMR structure of the N-terminal domain of E-coli DnaB helicase:: implications for structure rearrangements in the helicase hexamer
复制标题
大肠杆菌 DnaB 螺旋酶 N 端结构的核磁共振结构：对螺旋酶六聚体结构重排的影响
DOI：
10.1016/s0969-2126(99)80089-6
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发表时间：
1999-06-15
期刊：
影响因子：
--
通讯作者：
Otting, G
中科院分区：
文献类型：
--
作者：
Weigelt, J;Brown, SE;Otting, G
背景：DnaB是大肠杆菌中主要的复制解旋酶。天然DnaB是相同亚基的六聚体，每个亚基由较大的C-末端结构域和较小的N-末端结构域组成。电子显微镜数据显示具有C-6或C-3对称性的六聚体，表明大的结构域运动和可逆的成对缔合。用核磁共振（NMR）法测定了大肠杆菌DnaB的DNA含量。结构相似性被发现与拓扑异构酶的初级二聚化结构域，促旋酶A亚基从E。杆菌一个单体-二聚体的平衡，观察到隔离的N-末端结构域的DnaB。一个二聚体模型与C-2对称性来自分子间的核Overhauser效应，这是与所有可用的NMR data.Conclusions一致：观察到的单体-二聚体平衡的N-末端结构域的DnaB可能是解旋酶活性的功能意义，通过参与之间的开关C-6和C-3对称性的解旋酶六聚体。
Background: DnaB is the primary replicative helicase in Escherichia coli. Native DnaB is a hexamer of identical subunits, each consisting of a larger C-terminal domain and a smaller N-terminal domain. Electron-microscopy data show hexamers with C-6 or C-3 symmetry, indicating large domain movements and reversible pairwise association.Results: The three-dimensional structure of the N-terminal domain of E. coli DnaB was determined by nuclear magnetic resonance (NMR) spectroscopy. Structural similarity was found with the primary dimerisation domain of a topoisomerase, the gyrase A subunit from E. coli. A monomer-dimer equilibrium was observed for the isolated N-terminal domain of DnaB. A dimer model with C-2 symmetry was derived from intermolecular nuclear Overhauser effects, which is consistent with all available NMR data.Conclusions: The monomer-dimer equilibrium observed for the N-terminal domain of DnaB is likely to be of functional significance for helicase activity, by participating in the switch between C-6 and C-3 symmetry of the helicase hexamer.