Zhang Min, Hu Yong, Jia Jingjing, Li Dapeng, Zhang Runjie, Gao Hongbo, He Yikun
College of Life Science, Capital Normal University, Beijing, China.
Cell Res. 2009 Jul;19(7):877-86. doi: 10.1038/cr.2009.78.
Chloroplasts are plant-specific organelles that evolved from endosymbiotic cyanobacteria. They divide through binary fission. Selection of the chloroplast division site is pivotal for the symmetric chloroplast division. In E. coli, positioning of the division site at the midpoint of the cell is regulated by dynamic oscillation of the Min system, which includes MinC, MinD and MinE. Homologs of MinD and MinE in plants are involved in chloroplast division. The homolog of MinC still has not been identified in higher plants. However, an FtsZ-like protein, ARC3, was found to be involved in chloroplast division site positioning. Here, we report that chloroplast division site positioning 1 (AtCDP1) is a novel chloroplast division protein involved in chloroplast division site placement in Arabidopsis. AtCDP1 was discovered by screening an Arabidopsis cDNA expression library in bacteria for colonies with a cell division phenotype. AtCDP1 is exclusively expressed in young green tissues in Arabidopsis. Elongated chloroplasts with multiple division sites were observed in the loss-of-function cdp1 mutant. Overexpression of AtCDP1 caused a chloroplast division phenotype too. Protein interaction assays suggested that AtCDP1 may mediate the chloroplast division site positioning through the interaction with ARC3. Overall, our results indicate that AtCDP1 is a novel component of the chloroplast division site positioning system, and the working mechanism of this system is different from that of the traditional MinCDE system in prokaryotic cells.
叶绿体是植物特有的细胞器,由内共生蓝细菌进化而来。它们通过二分裂进行分裂。叶绿体分裂位点的选择对于叶绿体的对称分裂至关重要。在大肠杆菌中,细胞分裂位点在细胞中点的定位由Min系统的动态振荡调节,该系统包括MinC、MinD和MinE。植物中MinD和MinE的同源物参与叶绿体分裂。在高等植物中尚未鉴定出MinC的同源物。然而,发现一种类FtsZ蛋白ARC3参与叶绿体分裂位点的定位。在这里,我们报道叶绿体分裂位点定位蛋白1(AtCDP1)是一种新的叶绿体分裂蛋白,参与拟南芥中叶绿体分裂位点的定位。AtCDP1是通过在细菌中筛选拟南芥cDNA表达文库以寻找具有细胞分裂表型的菌落而发现的。AtCDP1仅在拟南芥的幼嫩绿色组织中表达。在功能缺失的cdp1突变体中观察到具有多个分裂位点的细长叶绿体。AtCDP1的过表达也导致叶绿体分裂表型。蛋白质相互作用分析表明,AtCDP1可能通过与ARC3相互作用介导叶绿体分裂位点的定位。总体而言,我们的结果表明AtCDP1是叶绿体分裂位点定位系统的一个新组分,并且该系统的工作机制与原核细胞中传统的MinCDE系统不同。