Structural basis for regulation of bifunctional roles in replication initiator protein
Structural basis for regulation of bifunctional roles in replication initiator protein
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DOI：
10.1073/pnas.0705623104
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发表时间：
2007-11-20
影响因子：
11.1
通讯作者：
Miki, Kunio
中科院分区：
文献类型：
--
作者：
Nakamura, Akira;Wada, Chieko;Miki, Kunio
DNA复制起始蛋白RepE通过两种不同的分子缔合状态严格调控F质粒的复制。一个主要的二聚体作为一个自体阻遏物的功能，而单体作为复制引发剂，和二聚体需要的行动DnaK分子伴侣系统的单体化。单体形式的结构是已知的，而二聚体结构和二聚体至单体转化的结构细节尚不清楚。在这里，我们提出的RepE二聚体的晶体结构与repE操作DNA的复杂。二聚化界面主要由分子间P-片层与带电残基的几个关键相互作用形成。内部N-和C-末端结构域的构象是保守的二聚体和单体之间，而相对结构域的方向是惊人的不同，允许一个有效的寡聚过渡的双功能RepE。这种结构域的重新定位伴随着连接两个结构域的接头中的二级结构变化，并且接头包括在合理的DnaK/DnaJ结合区域中。这些发现表明，F质粒复制的RepE单体化，这是诱导和介导的DnaK系统的激活机制。
DNA replication initiator protein RepE stringently regulates F plasmid replication by its two distinct molecular association states. A predominant dimer functions as an autogenous repressor, whereas monomers act as replication initiators, and the dimer requires actions of the DnaK molecular chaperone system for monomerization. The structure of the monomeric form is known, whereas the dimeric structure and structural details of the dimer-to-monomer conversion have been unclear. Here we present the crystal structure of the RepE dimer in complex with the repE operator DNA. The dimerization interface is mainly formed by intermolecular P-sheets with several key interactions of charged residues. The conformations of the internal N- and C-terminal domains are conserved between the dimer and monomer, whereas the relative domain orientations are strikingly different, allowing for an efficient oligomeric transition of dual-functional RepE. This domain relocation accompanies secondary structural changes in the linker connecting the two domains, and the linker is included in plausible DnaK/DnaJ-binding regions. These findings suggest an activation mechanism for F plasmid replication by RepE monomerization, which is induced and mediated by the DnaK system.