Ikebe Ryosuke, Kuwabara Yuri, Chikada Taiki, Niki Hironori, Shiomi Daisuke
Department of Life Science, College of Science, Rikkyo University, Tokyo, Japan.
Microbial Genetics Laboratory, Genetic Strains Research Center, National Institute of Genetics, Mishima, Shizuoka, Japan.
Genes Cells. 2018 Apr;23(4):307-317. doi: 10.1111/gtc.12572. Epub 2018 Feb 26.
Rod shape of bacterial cells such as Escherichia coli is mainly regulated by a supramolecular complex called elongasome including MreB actin. Deletion of the mreB gene in rod-shaped bacterium E. coli results in round-shaped cells. RodZ was isolated as a determinant of rod shape in E. coli, Caulobacter crescentus and Bacillus subtilis and it has been shown to be an interaction partner and a regulator of assembly of MreB through its cytoplasmic domain. As opposed to functions of the N-terminal cytoplasmic domain of RodZ, functions of the C-terminal periplasmic domain including a disordered region are still unclear. To understand it, we adopted an in vivo photo-cross-linking assay to analyze interaction partners to identify proteins which interact with RodZ via its periplasmic domain, finding that the RodZ self-interacts in the periplasmic disordered domain. Self-interaction of RodZ was affected by MreB actin. Deletion of this region resulted in aberrant cell shape. Our results suggest that MreB binding to the cytoplasmic domain of RodZ causes structural changes in the disordered periplasmic domain of RodZ. We also found that the disordered domain of RodZ contributes to fine-tune rod shape in E. coli.
诸如大肠杆菌等细菌细胞的杆状形态主要由一种名为伸长体的超分子复合物调控，该复合物包括MreB肌动蛋白。在杆状细菌大肠杆菌中缺失mreB基因会导致细胞呈圆形。RodZ在大肠杆菌、新月柄杆菌和枯草芽孢杆菌中被分离出来作为杆状形态的决定因素，并且已经表明它是MreB的相互作用伙伴，通过其胞质结构域调节MreB的组装。与RodZ的N端胞质结构域的功能相反，包括一个无序区域的C端周质结构域的功能仍不清楚。为了弄清楚这一点，我们采用了体内光交联分析来分析相互作用伙伴，以鉴定通过其周质结构域与RodZ相互作用的蛋白质，发现RodZ在周质无序结构域中发生自我相互作用。RodZ的自我相互作用受MreB肌动蛋白影响。删除该区域会导致异常的细胞形态。我们的结果表明，MreB与RodZ的胞质结构域结合会导致RodZ无序周质结构域发生结构变化。我们还发现，RodZ的无序结构域有助于微调大肠杆菌的杆状形态。
