title: Involvement of Arabidopsis Hexokinase1 in Cell Death Mediated by Myo-Inositol Accumulation.
abstract: Programmed cell death (PCD) is essential for several aspects of plant life, including development and stress responses. We recently identified the mips1 mutant of Arabidopsis thaliana, which is deficient for the enzyme catalyzing the limiting step of myo-inositol (MI) synthesis. One of the most striking features of mips1 is the light-dependent formation of lesions on leaves due to salicylic acid (SA)-dependent PCD. Here, we identified a suppressor of PCD by screening for mutations that abolish the mips1 cell death phenotype. Our screen identified the hxk1 mutant, mutated in the gene encoding the hexokinase1 (HXK1) enzyme that catalyzes sugar phosphorylation and acts as a genuine glucose sensor. We show that HXK1 is required for lesion formation in mips1 due to alterations in MI content, via SA-dependant signaling. Using two catalytically inactive HXK1 mutants, we also show that hexokinase catalytic activity is necessary for the establishment of lesions in mips1. Gas chromatography-mass spectrometry analyses revealed a restoration of the MI content in mips1 hxk1 that it is due to the activity of the MIPS2 isoform, while MIPS3 is not involved. Our work defines a pathway of HXK1-mediated cell death in plants and demonstrates that two MIPS enzymes act cooperatively under a particular metabolic status, highlighting a novel checkpoint of MI homeostasis in plants.
authors.affiliation: Université Paris-Sud, Institute of Plant Sciences Paris-Saclay IPS2 (Bâtiment 630), UMR CNRS-INRA 9213, Saclay Plant Sciences, 91405 Orsay, France.
authors.forename: Quentin
authors.initials: Q
authors.lastname: Bruggeman
authors.affiliation: Université Paris-Sud, Institute of Plant Sciences Paris-Saclay IPS2 (Bâtiment 630), UMR CNRS-INRA 9213, Saclay Plant Sciences, 91405 Orsay, France.
authors.forename: Florence
authors.initials: F
authors.lastname: Prunier
authors.affiliation: Université Paris-Sud, Institute of Plant Sciences Paris-Saclay IPS2 (Bâtiment 630), UMR CNRS-INRA 9213, Saclay Plant Sciences, 91405 Orsay, France.
authors.forename: Christelle
authors.initials: C
authors.lastname: Mazubert
authors.affiliation: Université Paris-Sud, Institute of Plant Sciences Paris-Saclay IPS2 (Bâtiment 630), UMR CNRS-INRA 9213, Saclay Plant Sciences, 91405 Orsay, France.
authors.forename: Linda
authors.initials: L
authors.lastname: de Bont
authors.affiliation: Université Paris-Sud, Institute of Plant Sciences Paris-Saclay IPS2 (Bâtiment 630), UMR CNRS-INRA 9213, Saclay Plant Sciences, 91405 Orsay, France.
authors.forename: Marie
authors.initials: M
authors.lastname: Garmier
authors.affiliation: Institut de Biologie Moléculaire des Plantes, Unité Propre de Recherche 2357 CNRS, Université de Strasbourg, 67084 Strasbourg Cedex, France.
authors.forename: Raphaël
authors.initials: R
authors.lastname: Lugan
authors.affiliation: Université Paris-Sud, Institute of Plant Sciences Paris-Saclay IPS2 (Bâtiment 630), UMR CNRS-INRA 9213, Saclay Plant Sciences, 91405 Orsay, France Division of Biological and Environmental Sciences and Engineering, Center for Desert Agriculture, King Abdullah University of Science and Technology, Thuwal 23955-6900, Kingdom of Saudi Arabia.
authors.forename: Moussa
authors.initials: M
authors.lastname: Benhamed
authors.affiliation: Université Paris-Sud, Institute of Plant Sciences Paris-Saclay IPS2 (Bâtiment 630), UMR CNRS-INRA 9213, Saclay Plant Sciences, 91405 Orsay, France.
authors.forename: Catherine
authors.initials: C
authors.lastname: Bergounioux
authors.affiliation: Université Paris-Sud, Institute of Plant Sciences Paris-Saclay IPS2 (Bâtiment 630), UMR CNRS-INRA 9213, Saclay Plant Sciences, 91405 Orsay, France.
authors.forename: Cécile
authors.initials: C
authors.lastname: Raynaud
authors.affiliation: Université Paris-Sud, Institute of Plant Sciences Paris-Saclay IPS2 (Bâtiment 630), UMR CNRS-INRA 9213, Saclay Plant Sciences, 91405 Orsay, France marianne.delarue@u-psud.fr.
authors.forename: Marianne
authors.initials: M
authors.lastname: Delarue
mesh_terms: D017360:Arabidopsis / Q000201:enzymology / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D029681:Arabidopsis Proteins / Q000235:genetics / Q000502:physiology*; D016923:Cell Death / Q000502:physiology*; D008401:Gas Chromatography-Mass Spectrometry; D017343:Genes, Plant / Q000235:genetics / Q000502:physiology; D006593:Hexokinase / Q000235:genetics / Q000502:physiology*; D007294:Inositol / Q000378:metabolism / Q000502:physiology*
chemical_list: D029681:Arabidopsis Proteins; D007294:Inositol; D006593:Hexokinase; C473630:ATHXK1 protein, Arabidopsis