Rice ROOT ARCHITECTURE ASSOCIATED1 binds the proteasome subunit RPT4 and is degraded in a D-box and proteasome-dependent manner
Rice ROOT ARCHITECTURE ASSOCIATED1 binds the proteasome subunit RPT4 and is degraded in a D-box and proteasome-dependent manner
复制标题
DOI：
10.1104/pp.108.125294
复制
发表时间：
2008-10-01
期刊：
影响因子：
7.4
通讯作者：
Chong, Kang
中科院分区：
文献类型：
--
作者：
Han, Ye;Cao, Hong;Chong, Kang
根的生长主要取决于根尖区域的细胞分裂和随后的伸长。调控根分生组织细胞分裂的成分在很大程度上是未知的。先前的研究已经确定水稻（Oryza sativa）根系结构相关基因（ROOT ARCHITECTURE ASSOCIATED1, OsRAA1）在根系发育中起调节作用。然而，OsRAA1在细胞和分子水平上的功能尚不清楚。本研究表明，过表达OsRAA1的转基因水稻初生根生长减少，中期细胞数量增加，后期细胞数量减少，这表明OsRAA1通过抑制后期的发生来限制根的生长。OsRAA1在分裂酵母中的表达也能诱导中期阻滞，这与OsRAA1通过保守的细胞周期调控机制起作用是一致的。此外，共定位实验表明，OsRAA1在细胞分裂过程中主要在纺锤体上表达。酵母双杂交和拉下实验，以及双分子荧光互补实验都表明，OsRAA1与水稻同源的调控粒子aaa ATPASE4相互作用，这是一种参与泛素途径的成分。用26S蛋白酶体的特异性抑制剂处理转基因水稻，阻断了OsRAA1的降解，增加了中期的细胞数量。在转基因酵母中，OsRAA1中一个假定的泛素化靶向D-box （RGSLDLISL）突变中断了OsRAA1的破坏。这些结果表明，泛素化和蛋白酶组蛋白水解参与了OsRAA1的降解，这是后期开始的必要条件，OsRAA1可能作为细胞周期的一个新的调节因子，通过泛素-蛋白酶体途径调节根的发育。
Root growth is mainly determined by cell division and subsequent elongation in the root apical area. Components regulating cell division in root meristematic cells are largely unknown. Previous studies have identified rice (Oryza sativa) ROOT ARCHITECTURE ASSOCIATED1 (OsRAA1) as a regulator in root development. Yet, the function of OsRAA1 at the cellular and molecular levels is unclear. Here, we show that OsRAA1-overexpressed transgenic rice showed reduced primary root growth, increased numbers of cells in metaphase, and reduced numbers of cells in anaphase, which suggests that OsRAA1 is responsible for limiting root growth by inhibiting the onset of anaphase. The expression of OsRAA1 in fission yeast also induced metaphase arrest, which is consistent with the fact that OsRAA1 functions through a conserved mechanism of cell cycle regulation. Moreover, a colocalization assay has shown that OsRAA1 is expressed predominantly at spindles during cell division. Yeast two-hybrid and pull-down assays, as well as a bimolecular fluorescence complementation assay, all have revealed that OsRAA1 interacts with a rice homolog of REGULATORY PARTICLE TRIPLE-A ATPASE4, a component that is involved in the ubiquitin pathway. Treating transgenic rice with specific inhibitors of the 26S proteasome blocked the degradation of OsRAA1 and increased the number of cells in metaphase. Mutation of a putative ubiquitination-targeting D-box (RGSLDLISL) in OsRAA1 interrupted the destruction of OsRAA1 in transgenic yeast. These results suggest that ubiquitination and proteasomic proteolysis are involved in OsRAA1 degradation, which is essential for the onset of anaphase, and that OsRAA1 may modulate root development mediated by the ubiquitin-proteasome pathway as a novel regulatory factor of the cell cycle.