ITPK1 is an InsP_(6)/ADP phosphotransferase that controls phosphate signaling in Arabidopsis.  

作　　者：Esther Riemer Danye Qiu Debabrata Laha Robert K.Harmel Philipp Gaugler Verena Gaugler Michael Frei Mohammad-Reza Hajirezaei Nargis Parvin Laha Lukas Krusenbaum Robin Schneider Adolfo Saiardi Dorothea Fiedler Henning J.Jessen Gabriel Schaaf Ricardo F.H.Giehl 

机构地区：[1]Department of Plant Nutrition,Institute of Crop Science and Resource Conservation,Rheinische Friedrich-Wilhelms-Universitat Bonn,53115 Bonn,Germany [2]Department of Chemistry and Pharmacy and CIBSS-Centre for Integrative Biological Signalling Studies,Albert-Ludwigs University Freiburg,79104 Freiburg,Germany [3]Medical Research Council Laboratory for Molecular Cell Biology(MRC-LMCB),University College London,London WC1E 6BT,UK [4]Department of Biochemistry,Indian Institute of Science,Bengaluru,Karnataka 560012,India [5]Leibniz-Forschungsinstitut fur Molekulare Pharmakologie,13125 Berlin,Germany [6]Department of Chemistry,Humboldt Universitat zu Berlin,12489 Berlin,Germany [7]Institute of Agronomy and Crop Physiology,Justus-Liebig University Giessen,35392 Giessen,Germany [8]Department of Physiology&Cell Biology,Leibniz-lnstitute of Plant Genetics and Crop Plant Research,06466 Gatersleben,Germany

出　　处：《Molecular Plant》2021年第11期1864-1880,共17页分子植物（英文版）

基　　金：This work was funded by grants from the Deutsche Forschungsgemein-schaft(HE 8362/1-1,DFG Eigene Stelle,to R.F.H.G.;SCHA 1274/4-1,SCHA 1274/5-1,Research Training Group GRK 2064 and Germany's Excellence Strategy,EXC-2070-390732324,PhenoRob to G.S.;JE 572/4-1 and Germany's Excellence Strategy,ClBSS-EXC-2189-Project ID 390939984 to H.J.J;LA 4541/1-1 postdoctoral research fellowship to D.L.),grants from the Medical Research Council(MRC award MR/T028904/1 to A.S.),and a DBT-IISc Program to D.L.

摘　　要：In plants, phosphate (Pi) homeostasis is regulated by the interaction of PHR transcription factors with stand-alone SPX proteins, which act as sensors for inositol pyrophosphates. Here, we combined different methods to obtain a comprehensive picture of how inositol (pyro)phosphate metabolism is regulated by Pi and dependent on the inositol phosphate kinase ITPK1. We found that inositol pyrophosphates are more responsive to Pi than lower inositol phosphates, a response conserved across kingdoms. With CE-ESI-MS we could separate different InsP7 isomers in Arabidopsis and rice, and identify 4/6-InsP7 and a PP-InsP4 isomer hitherto not reported in plants. We found that the inositol pyrophosphates 1/3-InsP7, 5-InsP7 and InsP8 increase severalfold in shoots after Pi resupply and that tissue-specific accumulation of inositol pyrophosphates relies on ITPK1 activities and MRP5-dependent InsP6 compartmentalization. Notably, ITPK1 is critical for Pi-dependent 5-InsP7 and InsP8 synthesis in planta and its activity regulates Pi starvation responses in a PHR-dependent manner. Furthermore, we demonstrate that ITPK1-mediated conversion of InsP6 to 5-InsP7 requires high ATP concentrations and that Arabidopsis ITPK1 has an ADP phosphotransferase activity to dephosphorylate specifically 5-InsP7 under low ATP. Collectively, our study provides deeper insights into Pi-dependent changes in nutritional and energetic states with the synthesis of regulatory inositol pyrophosphates.

关 键 词：diphosphoinositol pentakisphosphate kinase inositol 1 3 4-trisphosphate 5/6-kinase 1 inositol phosphates inositol pyrophosphates phosphate homeostasis phosphate signaling 

分 类 号：Q946[生物学—植物学]