Feng Hui, Wang Sheng, Dong Dengfeng, Zhou Ruiyang, Wang Hong
College of Agriculture, Guangxi University, Nanning 530005, China.
Department of Biochemistry, Microbiology and Immunology, University of Saskatchewan, Saskatoon, SK S7N 5E5, Canada.
Plants (Basel). 2020 Jun 8;9(6):723. doi: 10.3390/plants9060723.
Protein ubiquitination plays important roles in plants, including stress responses. The ubiquitin (Ub) E2 enzymes are required in the transfer of Ub to a substrate and are also important in determining the Ub-chain linkage specificity. However, for many of the 37 E2 genes in , there is currently little or no understanding of their functions. In this study, we investigated three members of an E2 subfamily. The single, double, and triple mutants of , , and did not show any phenotypic changes under normal conditions, but were more sensitive than the wild-type (WT) plants to multiple stress conditions, suggesting that the three genes are not critical for normal growth, but required in plant stress responses. The severity of the phenotypes increased from single to triple mutants, suggesting that the functions of the three genes are not completely redundant. The three E2s are closely related to the yeast Ubc7 and its homologs in animals and human, which are an important component of the endoplasmic reticulum (ER)-associated degradation (ERAD) pathway. The stress sensitivity phenotypes of the mutants and shared evolutionary root with the Ubc7 homologs in yeast and metazoans suggest that UBC7, UBC13, and UBC14 may function in the plant ERAD pathway.
蛋白质泛素化在植物中发挥着重要作用，包括应激反应。泛素（Ub）E2酶在将Ub转移至底物的过程中是必需的，并且在决定Ub链连接特异性方面也很重要。然而，对于拟南芥中37个E2基因中的许多基因，目前对其功能了解甚少或几乎一无所知。在本研究中，我们调查了一个E2亚家族的三个成员。AtUBC7、AtUBC13和AtUBC14的单突变体、双突变体和三突变体在正常条件下未表现出任何表型变化，但比野生型（WT）植物对多种胁迫条件更敏感，这表明这三个基因对正常生长并非至关重要，但在植物应激反应中是必需的。表型的严重程度从单突变体到三突变体增加，表明这三个基因的功能并非完全冗余。这三个E2与酵母Ubc7及其在动物和人类中的同源物密切相关，它们是内质网（ER）相关降解（ERAD）途径的重要组成部分。突变体的应激敏感性表型以及与酵母和后生动物中Ubc7同源物的共同进化根源表明，UBC7、UBC13和UBC14可能在植物ERAD途径中发挥作用。
