Phosphorylation of the CAMTA3 Transcription Factor Triggers Its Destabilization and Nuclear Export
Phosphorylation of the CAMTA3 Transcription Factor Triggers Its Destabilization and Nuclear Export
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DOI：
10.1104/pp.20.00795
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发表时间：
2020-10-01
期刊：
影响因子：
7.4
通讯作者：
Lee, Justin
中科院分区：
文献类型：
--
作者：
Jiang, Xiyuan;Hoehenwarter, Wolfgang;Lee, Justin
拟南芥（Arabidopsis thaliana）钙调素结合转录激活因子3（CAMTA 3）是植物中免疫相关基因的阻遏物，但也是冷诱导或一般胁迫响应基因的激活物。已经提出转录后或翻译后机制来控制CAMTA 3在不同胁迫反应中的功能。在这里，我们表明，治疗与细菌flg22诱导CAMTA 3磷酸化，这是伴随着其不稳定和核输出。两种flg22响应性促分裂原活化蛋白激酶（MAPK）MPK 3和MPK 6直接磷酸化CAMTA 3，磷酸化位点有助于CAMTA 3降解和抑制下游靶基因表达。然而，对于MAPK修饰位点的CAMTA 3磷酸无效变体，仍然可以观察到flg22诱导的核输出和磷酸迁移率变化，这表明可能涉及另外的flg22响应性激酶。综上所述，我们认为flg22诱导的CAMTA 3耗竭促进下游防御靶基因的去阻遏，这涉及磷酸化、蛋白质周转增加和核质运输。
The Arabidopsis (Arabidopsis thaliana) calmodulin-binding transcription activator3 (CAMTA3) is a repressor of immunity-related genes but an activator of cold-induced or general stress-responsive genes in plants. Post-transcriptional or posttranslational mechanisms have been proposed to control CAMTA3 functions in different stress responses. Here, we show that treatment with the bacterial flg22 elicitor induces CAMTA3 phosphorylation, which is accompanied by its destabilization and nuclear export. Two flg22-responsive mitogen-activated protein kinases (MAPKs), MPK3 and MPK6, directly phosphorylate CAMTA3, with the phospho-sites contributing to CAMTA3 degradation and suppression of downstream target gene expression. However, the flg22-induced nuclear export and phospho-mobility shift can still be observed for the CAMTA3 phospho-null variant of the MAPK-modified sites, suggesting additional flg22-responsive kinases might be involved. Taken together, we propose that flg22-induced CAMTA3 depletion facilitates de-repression of downstream defense target genes, which involves phosphorylation, increased protein turnover, and nucleo-cytoplasmic trafficking.