Centre for Bacterial Cell Biology, Institute for Cell and Molecular Biosciences, Newcastle University, Newcastle Upon Tyne, UK.
EMBO J. 2012 Mar 21;31(6):1542-55. doi: 10.1038/emboj.2012.6. Epub 2012 Jan 27.
Control of DNA replication initiation is essential for normal cell growth. A unifying characteristic of DNA replication initiator proteins across the kingdoms of life is their distinctive AAA+ nucleotide-binding domains. The bacterial initiator DnaA assembles into a right-handed helical oligomer built upon interactions between neighbouring AAA+ domains, that in vitro stretches DNA to promote replication origin opening. The Bacillus subtilis protein Soj/ParA has previously been shown to regulate DnaA-dependent DNA replication initiation; however, the mechanism underlying this control was unknown. Here, we report that Soj directly interacts with the AAA+ domain of DnaA and specifically regulates DnaA helix assembly. We also provide critical biochemical evidence indicating that DnaA assembles into a helical oligomer in vivo and that the frequency of replication initiation correlates with the extent of DnaA oligomer formation. This work defines a significant new regulatory mechanism for the control of DNA replication initiation in bacteria.
DNA 复制起始的控制对正常细胞生长至关重要。生命王国中所有 DNA 复制起始蛋白的一个共同特征是它们独特的 AAA+核苷酸结合结构域。细菌起始因子 DnaA 组装成右手螺旋寡聚体，该寡聚体基于相邻 AAA+结构域之间的相互作用，体外拉伸 DNA 以促进复制起始点打开。先前已经表明枯草芽孢杆菌蛋白 Soj/ParA 调节 DnaA 依赖性 DNA 复制起始；然而，这种控制的机制尚不清楚。在这里，我们报告说 Soj 与 DnaA 的 AAA+结构域直接相互作用，并特异性调节 DnaA 螺旋组装。我们还提供了关键的生化证据，表明 DnaA 在体内组装成螺旋寡聚体，并且复制起始的频率与 DnaA 寡聚体形成的程度相关。这项工作定义了细菌中 DNA 复制起始控制的一个重要的新调节机制。
