The Arabidopsis aminopeptidase LAP2 regulates plant growth, leaf longevity and stress response
The Arabidopsis aminopeptidase LAP2 regulates plant growth, leaf longevity and stress response
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DOI：
10.1111/j.1469-8137.2011.03758.x
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发表时间：
2011-01-01
期刊：
影响因子：
9.4
通讯作者：
Tsujimoto, Masafumi
中科院分区：
文献类型：
--
作者：
Waditee-Sirisattha, Rungaroon;Shibato, Junko;Tsujimoto, Masafumi
已知肽酶在所有生物体的多种生物过程中发挥关键作用。在高等植物中，绝大多数假定的氨肽酶仍未被表征。在这项研究中，我们通过 cDNA 克隆、T-DNA 插入突变体的分离、酶活性的表征、基因表达的表征以及突变体的转录组学和代谢组学分析，对拟南芥 LAP2 进行了功能和表达分析。LAP2（拟南芥中 28 种氨肽酶之一）功能丧失，营养性减少生长，加速叶子衰老并使植物对各种胁迫更加敏感。 LAP2 在叶维管组织和静止中心区域高表达。整体基因表达和代谢物分析的整合表明 LAP2 控制细胞内氨基酸周转。该突变体通过上调亮氨酸生物合成的关键基因来维持游离亮氨酸。然而，这显着影响了谷氨酸的通量。结果，γ-氨基丁酸（一种源自谷氨酸的代谢物）在突变体中减少了。这些富氮化合物的减少与突变体的形态改变和应激敏感性相关。结果表明，LAP2确实是一种具有酶活性的氨肽酶，在衰老、应激反应和氨基酸周转中发挥着关键作用。
Peptidases are known to play key roles in multiple biological processes in all living organisms. In higher plants, the vast majority of putative aminopeptidases remain uncharacterized.In this study, we performed functional and expression analyses of the Arabidopsis LAP2 through cDNA cloning, isolation of T-DNA insertional mutants, characterization of the enzymatic activity, characterization of gene expression and transcriptomics and metabolomics analyses of the mutants.Loss of function of LAP2, one of the 28 aminopeptidases in Arabidopsis, reduced vegetative growth, accelerated leaf senescence and rendered plants more sensitive to various stresses. LAP2 is highly expressed in the leaf vascular tissue and the quiescent center region. Integration of global gene expression and metabolite analyses suggest that LAP2 controlled intracellular amino acid turnover. The mutant maintained free leucine by up-regulating key genes for leucine biosynthesis. However, this influenced the flux of glutamate strikingly. As a result, gamma-aminobutyric acid, a metabolite that is derived from glutamate, was diminished in the mutant. Decrements in these nitrogen-rich compounds are associated with morphological alterations and stress sensitivity of the mutant.The results indicate that LAP2 is indeed an enzymatically active aminopeptidase and plays key roles in senescence, stress response and amino acid turnover.