The Arabidopsis homologs of CCR4-associated factor 1 show mRNA deadenylation activity and play a role in plant defence responses
The Arabidopsis homologs of CCR4-associated factor 1 show mRNA deadenylation activity and play a role in plant defence responses
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CCR4 相关因子 1 的拟南芥同源物显示 mRNA 去腺苷酸化活性，并在植物防御反应中发挥作用
DOI：
10.1038/cr.2008.317
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发表时间：
2009-03-01
期刊：
影响因子：
44.1
通讯作者：
Li, Chuanyou
中科院分区：
文献类型：
--
作者：
Liang, Wenxing;Li, Changbao;Li, Chuanyou
真核细胞中的信使 RNA (mRNA) 更新始于 3' 端 Poly (A) 尾部的缩短，这一过程称为脱腺苷化。在酵母中，脱腺苷酸化反应主要由 CCR4 和 CCR4 相关因子 1 (CAF1) 介导，这两个成分是名为 CCR4-NOT 的已充分表征的蛋白质复合物的两个组成部分。我们在此报告，AtCAF1a 和 AtCAF1b（酵母 CAF1 基因的假定拟南芥同源物）部分弥补了酵母 caf1 突变体在咖啡因存在或高温下的生长缺陷。 AtCAF1a 和 AtCAF1b 的表达是由多种应激相关激素和刺激诱导的。 AtCAF1a 和 AtCAF1b 均在体外表现出去腺苷酸化活性，预测活性位点的点突变会破坏该活性。破坏 AtCAF1a 和/或 AtCAF1b 表达的 T-DNA 插入突变体在应激相关 mRNA 的去腺苷化方面存在缺陷，表明这两种 AtCAF1 蛋白参与体内调节的 mRNA 去腺苷化。有趣的是，AtCAF1a和AtCAF1b的单突变体和双突变体表现出发病相关（PR）基因PR1和PR2的表达降低，并且更容易受到丁香假单胞菌番茄致病变种DC3000（Pst DC3000）感染，而过表达AtCAF1a的转基因植物表现出PR1和PR2的表达升高以及对相同病原体的抗性增强。我们的结果表明 AtCAF1 蛋白在调节 mRNA 脱腺苷化和对病原体感染的防御反应中的作用。
Messenger RNA (mRNA) turnover in eukaryotic cells begins with shortening of the poly (A) tail at the 3' end, a process called deadenylation. In yeast, the deadenylation reaction is predominantly mediated by CCR4 and CCR4-associated factor 1 (CAF1), two components of the well-characterised protein complex named CCR4-NOT. We report here that AtCAF1a and AtCAF1b, putative Arabidopsis homologs of the yeast CAF1 gene, partially complement the growth defect of the yeast caf1 mutant in the presence of caffeine or at high temperatures. The expression of AtCAF1a and AtCAF1b is induced by multiple stress-related hormones and stimuli. Both AtCAF1a and AtCAF1b show deadenylation activity in vitro and point mutations in the predicted active sites disrupt this activity. T-DNA insertion mutants disrupting the expression of AtCAF1a and/or AtCAF1b are defective in deadenylation of stress-related mRNAs, indicating that the two AtCAF1 proteins are involved in regulated mRNA deadenylation in vivo. Interestingly, the single and double mutants of AtCAF1a and AtCAF1b show reduced expression of pathogenesis-related (PR) genes PR1 and PR2 and are more susceptible to Pseudomonas syringae pv tomato DC3000 (Pst DC3000) infection, whereas transgenic plants over-expressing AtCAF1a show elevated expression of PR1 and PR2 and increased resistance to the same pathogen. Our results suggest roles of the AtCAF1 proteins in regulated mRNA deadenylation and defence responses to pathogen infections.