Cell cycle function of a rice B2-type cyclin interacting with a B-type cyclin-dependent kinase
Cell cycle function of a rice B2-type cyclin interacting with a B-type cyclin-dependent kinase
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DOI：
10.1046/j.1365-313x.2003.01736.x
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发表时间：
2003-05-01
期刊：
影响因子：
7.2
通讯作者：
Umeda, M
中科院分区：
文献类型：
--
作者：
Lee, J;Das, A;Umeda, M
细胞周期蛋白依赖性蛋白激酶(CDK)参与细胞周期进程的调控。植物A型CDK是酵母CDc2/CDc28的功能同源物，在整个细胞周期中都有表达。相比之下，B型CDK(CDKb)是一个在S/M期表达的有丝分裂CDK家族，其确切功能尚不清楚。在这里，我们鉴定了两个B2型细胞周期蛋白，CycB2；1和CycB2；2，作为水稻CDKB2；1.昆虫细胞产生的CDKB2；1-CycB2复合体在体外表现出显著的激酶活性，表明CycB2与CDKB2结合并激活CDKB2。然后，我们在烟草BY2细胞中表达了绿色荧光蛋白(GFP)融合的CDKB2；1和CycB2；2，以研究它们在有丝分裂过程中的亚细胞定位。令人惊讶的是，CDKB2；1-GFP的荧光信号不仅与中期染色体排列密切相关，而且与纺锤体结构密切相关。在末期，信号定位于纺锤体中间区和分离的姊妹染色体，然后定位于成膜体。而CycB2；2-GFP荧光信号则在细胞分裂间期和前期在细胞核内检测到，并移至中期染色体，在细胞经过中期后完全消失。CDKB2；1-GFP和CycB2；2-GFP在中期细胞中心排列的染色体上的共同定位表明，CDKB2-CycB2复合体可能具有保留中期板染色体的功能。CycB2；2在水稻植株中的过表达导致根的生长加速，但细胞大小没有增加，这表明CycB2；2可能通过与根分生组织中的CDKB2结合来促进细胞分裂。
Cyclin-dependent kinases (CDKs) are involved in the control of cell cycle progression. Plant A-type CDKs are functional homologs of yeast Cdc2/Cdc28 and are expressed throughout the cell cycle. In contrast, B-type CDK (CDKB) is a family of mitotic CDKs expressed during the S/M phase, and its precise function remains unknown. Here, we identified two B2-type cyclins, CycB2;1 and CycB2;2, as a specific partner of rice CDKB2;1. The CDKB2;1-CycB2 complexes produced in insect cells showed a significant level of kinase activity in vitro , suggesting that CycB2 binds to and activates CDKB2. We then expressed green fluorescent protein (GFP)-fused CDKB2;1 and CycB2;2 in tobacco BY2 cells to investigate their subcellular localization during mitosis. Surprisingly, the fluorescence signal of CDKB2;1-GFP was tightly associated with chromosome alignment as well as with spindle structure during the metaphase. During the telophase, the signal was localized to the spindle midzone and the separating sister chromosomes, and then to the phragmoplast. On the other hand, the CycB2;2-GFP fluorescence signal was detected in nuclei during the interphase and prophase, moved to the metaphase chromosomes, and then disappeared completely after the cells passed through the metaphase. Co-localization of CDKB2;1-GFP and CycB2;2-GFP on chromosomes aligned at the center of the metaphase cells suggests that the CDKB2-CycB2 complex may function in retaining chromosomes at the metaphase plate. Overexpression of CycB2;2 in rice plants resulted in acceleration of root growth without any increase in cell size, indicating that CycB2;2 promoted cell division probably through association with CDKB2 in the root meristem.