Li Lan, Li Bin, Xie Chong, Zhang Teng, Borassi Cecilia, Estevez José M, Li Xiushan, Liu Xuanming
College of Biology, State Key Laboratory of Chemo/Biosensing and Chemometrics and Hunan Key Laboratory of Plant Functional Genomics and Developmental Regulation Hunan University, Changsha, P. R. China.
Fundación Instituto Leloir and IIBBA-CONICET, Av. Patricias Argentinas 435, Buenos Aires CP, Argentina.
J Exp Bot. 2020 Jul 6;71(14):4010-4019. doi: 10.1093/jxb/eraa167.
The ubiquitin (Ub)/26S proteasome system (UPS) plays a key role in plant growth, development, and survival by directing the turnover of numerous regulatory proteins. In the UPS, the ubiquitin-like (UBL) and ubiquitin-associated (UBA) domains function as hubs for ubiquitin-mediated protein degradation. Radiation sensitive 23 (RAD23), which has been identified as a UBL/UBA protein, contributes to the progression of the cell cycle, stress responses, ER proteolysis, and DNA repair. Here, we report that pollen development is arrested at the microspore stage in a rad23b null mutant. We demonstrate that RAD23B can directly interact with KIP-related protein 1 (KRP1) through its UBL-UBA domains. In addition, plants overexpressing KRP1 have defects in pollen development, which is a phenotype similar to the rad23b mutant. RAD23B promotes the degradation of KRP1 in vivo, which is accumulated following treatment with the proteasome inhibitor MG132. Our results indicate that RAD23B plays an important in pollen development by controlling the turnover of the key cell cycle protein, KRP1.
泛素（Ub）/26S蛋白酶体系统（UPS）通过指导众多调节蛋白的周转，在植物生长、发育和存活中起关键作用。在UPS中，类泛素（UBL）和泛素相关（UBA）结构域作为泛素介导的蛋白质降解的枢纽。辐射敏感23（RAD23）已被鉴定为一种UBL/UBA蛋白，它有助于细胞周期进程、应激反应、内质网蛋白水解和DNA修复。在此，我们报道在rad23b缺失突变体中，花粉发育停滞在小孢子阶段。我们证明RAD23B可以通过其UBL-UBA结构域直接与KIP相关蛋白1（KRP1）相互作用。此外，过表达KRP1的植物在花粉发育上存在缺陷，这是一种与rad23b突变体表型相似的现象。RAD23B在体内促进KRP1的降解，在用蛋白酶体抑制剂MG132处理后KRP1会积累。我们的结果表明，RAD23B通过控制关键细胞周期蛋白KRP1的周转，在花粉发育中起重要作用。
