ITPK1-Dependent Inositol Polyphosphates Regulate Auxin Responses inArabidopsis thaliana
| Autor: | Gabriel Schaaf, Eva Maria Schaefer, Hitika Gulabani, Yashika Walia Dhir, Zhaleh Haghighat Shishavan, Philipp Gaugler, Nargis Parvin Laha, Debabrata Laha, Haibin Mao, Ricardo Fabiano Hettwer Giehl, Adolfo Saiardi, Saikat Bhattacharjee, Nicolaus von Wirén, Ning Zheng, Henning J. Jessen |
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| Rok vydání: | 2020 |
| Předmět: |
0106 biological sciences
chemistry.chemical_classification endocrine system 0303 health sciences biology Chemistry Kinase food and beverages Repressor biology.organism_classification 01 natural sciences Yeast Cell biology carbohydrates (lipids) 03 medical and health sciences chemistry.chemical_compound Auxin Arabidopsis Phosphorylation Arabidopsis thaliana Inositol 030304 developmental biology 010606 plant biology & botany |
| Popis: | The combinatorial phosphorylation ofmyo-inositolresults in the generation of different inositol phosphates (InsP), of which phytic acid (InsP6) is the most abundant species in eukaryotes. InsP6is also the precursor of higher phosphorylated forms called inositol pyrophosphates (PP-InsPs), such as InsP7and 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 InsP6kinases. Recently, it was shown that Arabidopsis ITPK1 catalyzes the phosphorylation of InsP6to the natural 5-InsP7isomerin vitro. Here, we demonstrate that Arabidopsis ITPK1 contributes to the synthesis of InsP7in planta. We further find a critical role of ITPK1 in auxin-related processes including primary root elongation, leaf venation, thermomorphogenic and gravitropic responses, and sensitivity towards exogenously applied auxin. Notably, 5-InsP7binds to recombinant auxin receptor complex, consisting of the F-Box protein TIR1, ASK1 and the transcriptional repressor IAA7, with high affinity. Furthermore, a specific increase in 5-InsP7in a heterologous yeast expression system results in elevated interaction of the TIR1 homologs AFB1 and AFB2 with various AUX/IAA-type transcriptional repressors. We also identified a physical interaction between ITPK1 and TIR1, suggesting a dedicated channeling of an activating factor, such as 5-InsP7, to the auxin receptor complex. Our findings expand the mechanistic understanding of auxin perception and lay the biochemical and genetic basis to uncover physiological processes regulated by 5-InsP7. |
| Databáze: | OpenAIRE |
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