Aoyama Shoki, Terada Saki, Sanagi Miho, Hasegawa Yoko, Lu Yu, Morita Yoshie, Chiba Yukako, Sato Takeo, Yamaguchi Junji
Faculty of Science and Graduate School of Life Science, Hokkaido University, Sapporo, 060-0810, Japan.
Faculty of Science and Graduate School of Life Science, Hokkaido University, Sapporo, 060-0810, Japan.
Biochem Biophys Res Commun. 2017 Sep 9;491(1):33-39. doi: 10.1016/j.bbrc.2017.07.028. Epub 2017 Jul 6.
Ubiquitin ligases play important roles in regulating various cellular processes by modulating the protein function of specific ubiquitination targets. The Arabidopsis Tóxicos en Levadura (ATL) family is a group of plant-specific RING-type ubiquitin ligases that localize to membranes via their N-terminal transmembrane-like domains. To date, 91 ATL isoforms have been identified in the Arabidopsis genome, with several ATLs reported to be involved in regulating plant responses to environmental stresses. However, the functions of most ATLs remain unknown. This study, involving transcriptome database analysis, identifies ATL15 as a sugar responsive ATL gene in Arabidopsis. ATL15 expression was rapidly down-regulated in the presence of sugar. The ATL15 protein showed ubiquitin ligase activity in vitro and localized to plasma membrane and endomembrane compartments. Further genetic analyses demonstrated that the atl15 knockout mutants are insensitive to high glucose concentrations, whereas ATL15 overexpression depresses plant growth. In addition, endogenous glucose and starch amounts were reciprocally affected in the atl15 knockout mutants and the ATL15 overexpressors. These results suggest that ATL15 protein plays a significant role as a membrane-localized ubiquitin ligase that regulates sugar-responsive plant growth in Arabidopsis.
泛素连接酶通过调节特定泛素化靶标的蛋白质功能，在调控各种细胞过程中发挥重要作用。拟南芥酵母毒性（ATL）家族是一组植物特有的RING型泛素连接酶，它们通过其N端类似跨膜的结构域定位于膜上。到目前为止，在拟南芥基因组中已鉴定出91种ATL亚型，据报道有几种ATL参与调节植物对环境胁迫的反应。然而，大多数ATL的功能仍然未知。这项涉及转录组数据库分析的研究，将ATL15鉴定为拟南芥中一个糖响应性ATL基因。在有糖存在的情况下，ATL15的表达迅速下调。ATL15蛋白在体外显示出泛素连接酶活性，并定位于质膜和内膜区室。进一步的遗传分析表明，atl15敲除突变体对高葡萄糖浓度不敏感，而ATL15过表达则抑制植物生长。此外，atl15敲除突变体和ATL15过表达体中内源葡萄糖和淀粉含量相互受到影响。这些结果表明，ATL15蛋白作为一种定位于膜上的泛素连接酶，在调节拟南芥糖响应性植物生长中发挥着重要作用。
