INOSITOL (1,3,4) TRIPHOSPHATE 5/6 KINASE1-dependent inositol polyphosphates regulate auxin responses in Arabidopsis.
INOSITOL (1,3,4) TRIPHOSPHATE 5/6 KINASE1-dependent inositol polyphosphates regulate auxin responses in Arabidopsis.
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肌醇 (1,3,4) 三磷酸酯 5/6 激酶 1 依赖性肌醇多磷酸调节拟南芥中的生长素反应。
DOI：
10.1093/plphys/kiac425
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发表时间：
2022-11-28
期刊：
影响因子：
7.4
通讯作者：
Schaaf, Gabriel
中科院分区：
文献类型：
--
作者：
Laha, Nargis Parvin;Giehl, Ricardo F. H.;Riemer, Esther;Qiu, Danye;Pullagurla, Naga Jyothi;Schneider, Robin;Dhir, Yashika Walia;Yadav, Ranjana;Mihiret, Yeshambel Emewodih;Gaugler, Philipp;Gaugler, Verena;Mao, Haibin;Zheng, Ning;von Wiren, Nicolaus;Saiardi, Adolfo;Bhattacharjee, Saikat;Jessen, Henning J.;Laha, Debabrata;Schaaf, Gabriel
肌醇的组合磷酸化导致不同肌醇磷酸（InsPs）的产生，其中植酸（InsP 6）是真核生物中最丰富的种类。InsP 6也是更高磷酸化肌醇焦磷酸（PP-InsPs）的重要前体，例如InsP 7和InsP 8，其特征在于二磷酸部分并且也普遍存在于真核细胞中。虽然PP-InsPs调节动物和酵母中的各种细胞过程，但它们在植物中的生物合成和功能在很大程度上仍然难以捉摸，因为植物基因组不编码典型的InsP 6激酶。最近的研究表明，拟南芥（Arabidopsis thaliana）肌醇（1，3，4）三磷酸5/6激酶1（ITPK 1）和ITPK 2在体外显示InsP 6激酶活性，并且在植物中，ITPK 1刺激5-InsP 7和InsP 8合成并调节磷酸饥饿反应。在这里，我们报告了ITPK 1在生长素相关过程中的关键作用，这是独立的ITPK 1控制的磷酸盐饥饿反应的调节。这些过程包括主根伸长、根毛发育、叶片脉序、热形态发生和向重力反应以及对外源生长素的敏感性。我们发现，重组生长素受体复合物，由F-Box蛋白质转运抑制剂反应1（TIR 1），拟南芥SKP 1同源蛋白1（ASK 1），和转录抑制因子吲哚-3-乙酸诱导7（IAA 7），结合阴离子肌醇多磷酸具有高亲和力。我们进一步确定了ITPK 1和TIR 1之间的物理相互作用，表明5-InsP 7或另一种ITPK 1依赖性InsP/PP-InsP异构体的局部产生，以激活生长素受体复合物。最后，我们证明了ITPK 1和ITPK 2的功能冗余控制生长素的反应，推断从生长素不敏感的表型itpk 1 itpk 2双突变体植物。我们的研究结果扩展了对生长素感知的机械理解，并表明生长素受体附近产生的不同肌醇多磷酸有助于微调植物中生长素的敏感性。拟南芥肌醇（1，3，4）三磷酸5/6激酶1依赖性肌醇多磷酸结合生长素受体复合物并调节生长素反应。
The combinatorial phosphorylation of myo-inositol results in the generation of different inositol phosphates (InsPs), of which phytic acid (InsP6) is the most abundant species in eukaryotes. InsP6 is also an important precursor of the higher phosphorylated inositol pyrophosphates (PP-InsPs), such as InsP7 and InsP8, which are characterized by a diphosphate moiety and are also ubiquitously found in eukaryotic cells. While PP-InsPs regulate various cellular processes in animals and yeast, their biosynthesis and functions in plants has remained largely elusive because plant genomes do not encode canonical InsP6 kinases. Recent work has shown that Arabidopsis (Arabidopsis thaliana) INOSITOL (1,3,4) TRIPHOSPHATE 5/6 KINASE1 (ITPK1) and ITPK2 display in vitro InsP6 kinase activity and that, in planta, ITPK1 stimulates 5-InsP7 and InsP8 synthesis and regulates phosphate starvation responses. Here we report a critical role of ITPK1 in auxin-related processes that is independent of the ITPK1-controlled regulation of phosphate starvation responses. Those processes include primary root elongation, root hair development, leaf venation, thermomorphogenic and gravitropic responses, and sensitivity to exogenously applied auxin. We found that the recombinant auxin receptor complex, consisting of the F-Box protein TRANSPORT INHIBITOR RESPONSE1 (TIR1), ARABIDOPSIS SKP1 HOMOLOG 1 (ASK1), and the transcriptional repressor INDOLE-3-ACETIC ACID INDUCIBLE 7 (IAA7), binds to anionic inositol polyphosphates with high affinity. We further identified a physical interaction between ITPK1 and TIR1, suggesting a localized production of 5-InsP7, or another ITPK1-dependent InsP/PP-InsP isomer, to activate the auxin receptor complex. Finally, we demonstrate that ITPK1 and ITPK2 function redundantly to control auxin responses, as deduced from the auxin-insensitive phenotypes of itpk1 itpk2 double mutant plants. Our findings expand the mechanistic understanding of auxin perception and suggest that distinct inositol polyphosphates generated near auxin receptors help to fine-tune auxin sensitivity in plants. Arabidopsis INOSITOL (1,3,4) TRIPHOSPHATE 5/6 KINASE1-dependent inositol polyphosphates bind to the auxin receptor complex and regulate auxin responses.
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