Two Ubiquitin-Activating Systems Occur in Plants with One Playing a Major Role in Plant Immunity
Two Ubiquitin-Activating Systems Occur in Plants with One Playing a Major Role in Plant Immunity
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DOI：
10.1101/2021.09.02.458739
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发表时间：
2021-09
期刊：
影响因子：
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通讯作者：
Bangjun Zhou;Chaofeng Wang;Xuanyang Chen;Yi Zhang;Lirong Zeng
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作者：
Bangjun Zhou;Chaofeng Wang;Xuanyang Chen;Yi Zhang;Lirong Zeng
许多植物具有两种或两种以上的泛素激活酶（E1）。然而，目前还不清楚植物基因组的E1是否在各种途径中发挥同等作用。在这里，我们报告说，番茄和烟草编码双泛素激活系统（DUAS），其中E1的UBA 1和UBA 2显示不同的特异性，在充电四组E2。E1的C末端遍在蛋白折叠结构域在确定四组E2的充电差异特异性方面发挥着主要但不是唯一的作用。这两个系统在植物免疫中并不起同等作用，UBA 2的沉默只会损害宿主免疫。在差异电荷的E2中，第IV组成员UBC 32、UBC 33和UBC 34被证明是ER相关蛋白降解（ERAD）和植物免疫所必需的。与番茄一样，拟南芥UBC 32/33/34 E2三联体也通过其E1带不同电荷，并且对植物免疫是必需的。拟南芥UBC 32、UBC 33和UBC 34中功能的丧失不影响flg 22和elf 18触发的幼苗生长抑制，但导致ER胁迫耐受性的改变，这可能有助于突变体中植物免疫力的降低。我们的研究结果揭示了植物中的DUAS和一个以前未知的E1-ERAD相关的E2三联体模块在宿主免疫调节中的作用。一句话总结植物双泛素E1系统发挥不同的作用，在植物免疫的差异充电ERAD相关的E2 ER胁迫耐受性。
Many plants possess two or more ubiquitin-activating enzymes (E1). However, it is unclear whether the E1s of a plant genome play equivalent roles in various pathways. Here we report that tomato and tobacco encode dual ubiquitin-activating systems (DUAS) in which the E1s UBA1 and UBA2 display differential specificities in charging four groups of E2s. The C-terminal ubiquitin-folding domain of the E1s play a major but not sole role in determining the differential specificities of charging the four groups E2s. The dual systems do not play equivalent roles in plant immunity, with silence of UBA2 only compromising host immunity. Among the differentially charged E2s, group IV members UBC32, UBC33 and UBC34 are shown to be essential for ER-associated protein degradation (ERAD) and plant immunity. Like tomato, Arabidopsis UBC32/33/34 E2 triplet are also differentially charged by its E1s and are essential for plant immunity. Loss of function in Arabidopsis UBC32, UBC33 and UBC34 does not affect flg22 and elf18-triggered inhibition of seedling growth but results in alteration of ER stress tolerance, which likely contribute to the diminished plant immunity in the mutants. Our results uncover DUAS in plants and a previously unknown E1–ERAD-associated E2 triplet module in the regulation of host immunity. One sentence summary Plant dual ubiquitin E1 systems play distinct roles in plant immunity by differentially charging the ERAD-associated E2s for ER stress tolerance.