The Arabidopsis Aux/IAA protein family has diversified in degradation and auxin responsiveness
The Arabidopsis Aux/IAA protein family has diversified in degradation and auxin responsiveness
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DOI：
10.1105/tpc.105.039172
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发表时间：
2006-03-01
期刊：
影响因子：
11.6
通讯作者：
Callis, J
中科院分区：
文献类型：
--
作者：
Dreher, KA;Brown, J;Callis, J
生长素/吲哚乙酸（Aux/IAA）蛋白的快速降解对植物生长发育至关重要。结构域II残基先前被证明是所需的几个拟南芥Aux/IAA蛋白的降解。我们研究了其他全长家族成员的降解和使用荧光素酶（LUC）融合的结构域II外的N-末端残基的蛋白水解重要性。结构域I的消除不影响降解。然而，取代一个保守的赖氨酸结构域I和II之间的精氨酸专门损害基础降解，而不损害生长素介导的加速降解。IAA 8，IAA 9和IAA 28含有结构域II和保守的赖氨酸，但它们比以前表征的家族成员表达为LUC融合时降解得更慢，这表明结构域II外的序列影响蛋白水解。我们分析了IAA 31的降解，该区域有点类似于结构域II，但没有保守的赖氨酸，以及IAA 20，它缺乏结构域II和保守的赖氨酸。IAA 20：LUC和表位标记的IAA 20都是长寿的，它们的寿命不受生长素的影响。表位标记的IAA 31是长寿命的，像IAA 20，但相比之下，它表现出加速降解生长素。长寿命和生长素不敏感的Aux/IAA蛋白的存在表明它们可能在生长素信号转导中发挥新的作用。
Rapid, auxin-responsive degradation of multiple auxin/indole-3-acetic acid (Aux/IAA) proteins is essential for plant growth and development. Domain II residues were previously shown to be required for the degradation of several Arabidopsis thaliana Aux/IAA proteins. We examined the degradation of additional full-length family members and the proteolytic importance of N-terminal residues outside domain II using luciferase (LUC) fusions. Elimination of domain I did not affect degradation. However, substituting an Arg for a conserved Lys between domains I and II specifically impaired basal degradation without compromising the auxin-mediated acceleration of degradation. IAA8, IAA9, and IAA28 contain domain II and a conserved Lys, but they were degraded more slowly than previously characterized family members when expressed as LUC fusions, suggesting that sequences outside domain II influence proteolysis. We analyzed the degradation of IAA31, with a region somewhat similar to domain II but without the conserved Lys, and of IAA20, which lacks domain II and the conserved Lys. Both IAA20: LUC and epitope-tagged IAA20 were long-lived, and their longevity was not influenced by auxin. Epitope-tagged IAA31 was long-lived, like IAA20, but by contrast, it showed accelerated degradation in response to auxin. The existence of long-lived and auxin-insensitive Aux/IAA proteins suggests that they may play a novel role in auxin signaling.