Lin Yen-Ling, Chung Chin-Lin, Huang Pin-Jui, Chen Chun-Han, Fang Su-Chiung
Biotechnology Center in Southern Taiwan Academia Sinica Tainan Taiwan.
Agricultural Biotechnology Research Center Academia Sinica Taipei Taiwan.
Plant Direct. 2020 Sep 28;4(9):e00266. doi: 10.1002/pld3.266. eCollection 2020 Sep.
Small ubiquitin-like modifier (SUMO) conjugation, or SUMOylation, is a reversible post-translational modification that is important for regulation of many cellular processes including cell division cycle in the eukaryotic kingdom. However, only a portion of the components of the Chlamydomonas SUMOylation system are known and their functions and regulation investigated. The present studies are aimed at extending discovery and characterization of new components and improving the annotation and nomenclature of all known proteins and genes involved in the system. Even though only one copy of the heterodimerized SUMO-activating enzyme, and , was identified, the number of SUMO-conjugating enzymes (s) and SUMO proteases/isopeptidase was expanded in Chlamydomonas. Using the reconstituted SUMOylation system, we showed that SCE1, SCE2, and SCE3 have SUMO-conjugating activity. In addition to SUMOylation, components required for other post-translational modifications such as NEDDylation, URMylation, and UFMylation, were confirmed to be present in Chlamydomonas. Our data also showed that besides isopeptidase activity, the SUMO protease domain of SUPPRESSOR OF MAT3 7/SENTRIN-SPECIFIC PROTEASE 1 (SMT7/SENP1) has endopeptidase activity that is capable of processing SUMO precursors. Moreover, the key cell cycle regulators of Chlamydomonas E2F1, DP1, CDKG1, CYCD2, and CYCD3 were SUMOylated in vitro, suggesting SUMOylation may be part of regulatory pathway modulating cell cycle regulators.
小泛素样修饰物（SUMO）缀合，即SUMO化，是一种可逆的翻译后修饰，对真核生物界中包括细胞分裂周期在内的许多细胞过程的调控至关重要。然而，衣藻SUMO化系统中只有一部分成分是已知的，其功能和调控机制也有待研究。本研究旨在拓展新成分的发现和表征，并完善该系统中所有已知蛋白质和基因的注释及命名。尽管仅鉴定出一份异源二聚化的SUMO激活酶和，但衣藻中SUMO缀合酶（s）和SUMO蛋白酶/异肽酶的数量有所增加。利用重组的SUMO化系统，我们发现SCE1、SCE2和SCE3具有SUMO缀合活性。除了SUMO化，其他翻译后修饰（如NEDD化、URM化和UFM化）所需的成分也被证实存在于衣藻中。我们的数据还表明，除了异肽酶活性外，MAT3 7抑制因子/小泛素样修饰物特异性蛋白酶1（SMT7/SENP1）的SUMO蛋白酶结构域还具有能够加工SUMO前体的内肽酶活性。此外，衣藻关键的细胞周期调节因子E2F1、DP1、CDKG1、CYCD2和CYCD3在体外被SUMO化，这表明SUMO化可能是调节细胞周期调节因子的调控途径的一部分。
