Pom1 DYRK regulates localization of the Rga4 GAP to ensure bipolar activation of Cdc42 in fission yeast
Pom1 DYRK regulates localization of the Rga4 GAP to ensure bipolar activation of Cdc42 in fission yeast
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DOI：
10.1016/j.cub.2008.02.005
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发表时间：
2008-03-11
期刊：
影响因子：
9.2
通讯作者：
Shiozaki, Kazuhiro
中科院分区：
文献类型：
--
作者：
Tatebe, Hisashi;Nakano, Kentaro;Shiozaki, Kazuhiro
背景：在裂殖酵母裂殖酵母中，细胞生长只发生在圆柱形细胞的两端。在这种高度极化的生长过程中，微管负责细胞末端标记蛋白的放置，Teal-Tea 4/Wsh 3复合物，其招募Pom 1 DYRK家族蛋白激酶。Pom 1是生长位点的正确定位所必需的，Delta pom 1突变导致单极细胞growth.Results：Pom 1激酶与Rga 4物理相互作用，Rga 4具有Rho家族GTP酶的GAP（GTP酶激活蛋白）结构域。遗传和生物化学证据表明，Rga 4的功能作为GAP的Cdc 42 GTdR，一个进化上保守的调节F-肌动蛋白。CRIB（Cdc 42/Rac相互作用结合）-GFP显微镜显示，GTP结合的活性Cdc 42被浓缩到生长的细胞末端，伴随着发达的F-肌动蛋白结构，其中Rga 4 GAP被排除在外。单极Delta pom 1突变体不能从非生长细胞端消除Rga 4，导致GTP-Cdc 42向生长细胞端的单极分布。然而，突变失活的Rga 4允许Cdc 42是活跃在两端的三角洲pom 1细胞，这表明Rga 4的错误定位在三角洲pom 1突变体有助于其单极phenotype.Conclusions：Pom 1激酶招募到细胞两端的Tea 1-Tea 4/Wsh 3复合物是必不可少的适当的本地化的间隙Cdc 42，Rga 4，这确保双极本地化的GTP结合，活性Cdc 42。由于Cdc 42在F-肌动蛋白形成中的既定作用，这些观察为微管系统如何实现F-肌动蛋白的局部形成以产生细胞极性提供了新的见解。
Background: In the fission yeast Schizosaccharomyces pombe, cell growth takes place exclusively at both ends of the cylindrical cell. During this highly polarized growth, micro-tubules are responsible for the placement of the cell-end marker proteins, the Teal-Tea4/Wsh3 complex, which recruits the Pom1 DYRK-family protein kinase. Pom1 is required for proper positioning of growth sites, and the Delta pom1 mutation brings about monopolar cell growth.Results: Pom1 kinase physically interacts with Rga4, which has a GAP (GTPase-activating protein) domain for Rho-family GTPase. Genetic and biochemical evidence indicates that Rga4 functions as GAP for the Cdc42 GTPase, an evolutionarily conserved regulator of F-actin. CRIB (Cdc42/Rac interactive binding)-GFP microscopy has revealed that GTP-bound, active Cdc42 is concentrated to growing cell ends accompanied by developed F-actin structures, where the Rga4 GAP is excluded. The monopolar Delta pom1 mutant fails to eliminate Rga4 from the nongrowing cell end, resulting in monopolar distribution of GTP-Cdc42 to the growing cell end. However, mutational inactivation of Rga4 allows Cdc42 to be active at both ends of Delta pom1 cells, suggesting that mislocalization of Rga4 in the Delta pom1 mutant contributes to its monopolar phenotype.Conclusions: Pom1 kinase recruited to cell ends by the Tea1-Tea4/Wsh3 complex is essential for proper localization of a GAP for Cdc42, Rga4, which ensures bipolar localization of GTP-bound, active Cdc42. Because of the established role of Cdc42 in F-actin formation, these observations provide a new insight into how the microtubule system achieves localized formation of F-actin to generate cell polarity.