Laha Debabrata, Johnen Philipp, Azevedo Cristina, Dynowski Marek, Weiß Michael, Capolicchio Samanta, Mao Haibin, Iven Tim, Steenbergen Merel, Freyer Marc, Gaugler Philipp, de Campos Marília K F, Zheng Ning, Feussner Ivo, Jessen Henning J, Van Wees Saskia C M, Saiardi Adolfo, Schaaf Gabriel
Center for Plant Molecular Biology, University of Tübingen, 72076 Tübingen, Germany.
Medical Research Council Laboratory for Molecular Cell Biology, University College London, London WC1E 6BT, United Kingdom.
Plant Cell. 2015 Apr;27(4):1082-97. doi: 10.1105/tpc.114.135160. Epub 2015 Apr 21.
Diphosphorylated inositol polyphosphates, also referred to as inositol pyrophosphates, are important signaling molecules that regulate critical cellular activities in many eukaryotic organisms, such as membrane trafficking, telomere maintenance, ribosome biogenesis, and apoptosis. In mammals and fungi, two distinct classes of inositol phosphate kinases mediate biosynthesis of inositol pyrophosphates: Kcs1/IP6K- and Vip1/PPIP5K-like proteins. Here, we report that PPIP5K homologs are widely distributed in plants and that Arabidopsis thaliana VIH1 and VIH2 are functional PPIP5K enzymes. We show a specific induction of inositol pyrophosphate InsP8 by jasmonate and demonstrate that steady state and jasmonate-induced pools of InsP8 in Arabidopsis seedlings depend on VIH2. We identify a role of VIH2 in regulating jasmonate perception and plant defenses against herbivorous insects and necrotrophic fungi. In silico docking experiments and radioligand binding-based reconstitution assays show high-affinity binding of inositol pyrophosphates to the F-box protein COI1-JAZ jasmonate coreceptor complex and suggest that coincidence detection of jasmonate and InsP8 by COI1-JAZ is a critical component in jasmonate-regulated defenses.
二磷酸化肌醇多磷酸，也被称为肌醇焦磷酸，是重要的信号分子，可调节许多真核生物中的关键细胞活动，如膜运输、端粒维持、核糖体生物合成和细胞凋亡。在哺乳动物和真菌中，两类不同的肌醇磷酸激酶介导肌醇焦磷酸的生物合成：Kcs1/IP6K-和Vip1/PPIP5K样蛋白。在此，我们报道PPIP5K同源物在植物中广泛分布，拟南芥VIH1和VIH2是有功能的PPIP5K酶。我们展示了茉莉酸对肌醇焦磷酸InsP8的特异性诱导，并证明拟南芥幼苗中InsP8的稳态池和茉莉酸诱导池依赖于VIH2。我们确定了VIH2在调节茉莉酸感知以及植物对食草昆虫和坏死性真菌防御中的作用。计算机对接实验和基于放射性配体结合的重组分析表明，肌醇焦磷酸与F-box蛋白COI1-JAZ茉莉酸共受体复合物具有高亲和力结合，并表明COI1-JAZ对茉莉酸和InsP8的协同检测是茉莉酸调节防御中的关键组成部分。
