Department of Plant Biology, Michigan State University, East Lansing 48824-1312, Michigan, USA.
Department of Biological Sciences, Graduate School of Science, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan.
Nat Plants. 2016 Jun 20;2:16095. doi: 10.1038/nplants.2016.95.
Chloroplast division is driven by a ring containing FtsZ1 and FtsZ2 proteins, which originated from bacterial FtsZ, a tubulin-like protein; however, mechanistic details of the chloroplast FtsZ ring remain unclear. Here, we report that FtsZ1 and FtsZ2 can heteropolymerize into a contractible ring ex vivo. Fluorescently labelled FtsZ1 and/or FtsZ2 formed single rings in cells of the yeast Pichia pastoris. Photobleaching experiments indicated that co-assembly of FtsZ1 and FtsZ2 imparts polarity to polymerization. Assembly of FtsZ chimaeras revealed that the protofilaments assemble via heteropolymerization of FtsZ2 and FtsZ1. Contraction of the ring was accompanied by an increase in the filament turnover rate. Our findings suggest that the evolutionary duplication of FtsZ in plants may have increased the mobility and kinetics of FtsZ ring dynamics in chloroplast division. Thus, the gene duplication and heteropolymerization of chloroplast FtsZs may represent convergent evolution with eukaryotic tubulin.
叶绿体的分裂是由一个包含 FtsZ1 和 FtsZ2 蛋白的环驱动的，这些蛋白来源于细菌 FtsZ，一种类似于微管蛋白的蛋白质；然而，叶绿体 FtsZ 环的机制细节尚不清楚。在这里，我们报告说 FtsZ1 和 FtsZ2 可以在体外异源聚合形成可收缩的环。荧光标记的 FtsZ1 和/或 FtsZ2 在酵母毕赤酵母的细胞中形成单个环。光漂白实验表明，FtsZ1 和 FtsZ2 的共组装赋予聚合作用以极性。FtsZ 嵌合体的组装表明原丝通过 FtsZ2 和 FtsZ1 的异源聚合组装。环的收缩伴随着丝状周转率的增加。我们的研究结果表明，植物中 FtsZ 的进化复制可能增加了叶绿体分裂中 FtsZ 环动力学的流动性和动力学。因此，叶绿体 FtsZs 的基因复制和异源聚合可能代表与真核微管的趋同进化。
