Alternative splicing expands the repertoire of dominant JAZ repressors of jasmonate signaling.
Alternative splicing expands the repertoire of dominant JAZ repressors of jasmonate signaling.
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DOI：
10.1111/j.1365-313x.2010.04265.x
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发表时间：
2010-08
期刊：
影响因子：
--
通讯作者：
Howe GA
中科院分区：
文献类型：
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作者：
Chung HS;Cooke TF;Depew CL;Patel LC;Ogawa N;Kobayashi Y;Howe GA
茉莉酸 (JAs) 是脂肪酸衍生的信号化合物，可控制植物生长、发育和免疫的各个方面。 F-box 蛋白 COI1 既可作为茉莉酰基-L-异亮氨酸 (JA-Ile) 的受体，又可作为 E3-泛素连接酶复合物 (SCFCOI1) 的组成部分，该复合物以 JAZ 转录调节因子为目标进行降解。 JAZ 蛋白的一个关键特征是 C 端 Jas 基序，可介导 JA-Ile 依赖性与 COI1 的相互作用。在这里，我们表明，来自进化多样化植物的大多数 JAZ 基因都包含一个保守的内含子，该内含子将 Jas 基序分裂成 20 个 N 端和 7 个 C 端 (X5PY) 氨基酸子基序。在拟南芥 JAZ 家族的大多数成员中，涉及保留该内含子的选择性剪接事件会产生在 X5PY 序列之前被截短的蛋白质。体外 Pull-down 和酵母双杂交测定表明，在激素生物活性立体异构体 (3R,7S)-JA-Ile 存在的情况下，这些剪接变体与 COI1 形成稳定复合物的能力降低。 cDNA 过表达研究表明，一些（但不是全部）截短的剪接变体是 JA 信号传导的主要抑制因子。我们还表明，含有内含子的 JAZ10 基因组克隆的强组成型表达足以抑制 JA 反应。这些发现为 JAZ 亚型之间的功能差异提供了证据，并在 JAZ 前体 mRNA 的选择性剪接与 JA 信号输出的显性抑制之间建立了直接联系。我们提出，通过选择性剪接产生显性 JAZ 阻遏蛋白可减少与 JA 反应途径不适当或过度激活相关的负面后果。
Jasmonates (JAs) are fatty acid-derived signaling compounds that control diverse aspects of plant growth, development, and immunity. The F-box protein COI1 functions both as a receptor for jasmonoyl-L-isoleucine (JA-Ile) and as the component of an E3-ubiquitin ligase complex (SCFCOI1) that targets JAZ transcriptional regulators for degradation. A key feature of JAZ proteins is the C-terminal Jas motif that mediates JA-Ile-dependent interaction with COI1. Here, we show that most JAZ genes from evolutionarily diverse plants contain a conserved intron that splits the Jas motif into 20 N-terminal and 7 C-terminal (X5PY) amino acid submotifs. In most members of the Arabidopsis JAZ family, alternative splicing events involving retention of this intron generate proteins that are truncated before the X5PY sequence. In vitro pull-down and yeast two-hybrid assays indicate that these splice variants have reduced capacity to form stable complexes with COI1 in the presence of the bioactive stereoisomer of the hormone, (3R,7S)-JA-Ile. cDNA overexpression studies showed that some, but not all, truncated splice variants are dominant repressors of JA signaling. We also show that strong constitutive expression of an intron-containing JAZ10 genomic clone is sufficient to repress JA responses. These findings provide evidence for functional differences between JAZ isoforms, and establish a direct link between alternative splicing of JAZ pre-mRNA and dominant repression of JA signal output. We propose that production of dominant JAZ repressors by alternative splicing reduces the negative consequences associated with inappropriate or hyperactivation of the JA response pathway.