title: Protein phosphatase 2A (PP2A) regulatory subunit B'γ interacts with cytoplasmic ACONITASE 3 and modulates the abundance of AOX1A and AOX1D in Arabidopsis thaliana.
abstract: Organellar reactive oxygen species (ROS) signalling is a key mechanism that promotes the onset of defensive measures in stress-exposed plants. The underlying molecular mechanisms and feedback regulation loops, however, still remain poorly understood. Our previous work has shown that a specific regulatory B'γ subunit of protein phosphatase 2A (PP2A) is required to control organellar ROS signalling and associated metabolic adjustments in Arabidopsis thaliana. Here, we addressed the mechanisms through which PP2A-B'γ impacts on organellar metabolic crosstalk and ROS homeostasis in leaves. Genetic, biochemical and pharmacological approaches, together with a combination of data-dependent acquisition (DDA) and selected reaction monitoring (SRM) MS techniques, were utilized to assess PP2A-B'γ-dependent adjustments in Arabidopsis thaliana. We show that PP2A-B'γ physically interacts with the cytoplasmic form of aconitase, a central metabolic enzyme functionally connected with mitochondrial respiration, oxidative stress responses and regulation of cell death in plants. Furthermore, PP2A-B'γ impacts ROS homeostasis by controlling the abundance of specific alternative oxidase isoforms, AOX1A and AOX1D, in leaf mitochondria. We conclude that PP2A-B'γ-dependent regulatory actions modulate the functional status of metabolic enzymes that essentially contribute to intracellular ROS signalling and metabolic homeostasis in plants.
authors.affiliation: Department of Biochemistry, Molecular Plant Biology, University of Turku, FI-20014, Turku, Finland.
authors.forename: Grzegorz
authors.initials: G
authors.lastname: Konert
authors.affiliation: Department of Biochemistry, Molecular Plant Biology, University of Turku, FI-20014, Turku, Finland.
authors.forename: Andrea
authors.initials: A
authors.lastname: Trotta
authors.affiliation: Turku Centre for Biotechnology, University of Turku and Åbo Akademi University, FI-20014, Turku, Finland.
authors.forename: Petri
authors.initials: P
authors.lastname: Kouvonen
authors.affiliation: Department of Biochemistry, Molecular Plant Biology, University of Turku, FI-20014, Turku, Finland.
authors.forename: Moona
authors.initials: M
authors.lastname: Rahikainen
authors.affiliation: Department of Biochemistry, Molecular Plant Biology, University of Turku, FI-20014, Turku, Finland.
authors.forename: Guido
authors.initials: G
authors.lastname: Durian
authors.affiliation: Department of Biosciences, University of Helsinki, FI-00014, Helsinki, Finland.
authors.forename: Olga
authors.initials: O
authors.lastname: Blokhina
authors.affiliation: Department of Biosciences, University of Helsinki, FI-00014, Helsinki, Finland.
authors.forename: Kurt
authors.initials: K
authors.lastname: Fagerstedt
authors.affiliation: Turku Centre for Biotechnology, University of Turku and Åbo Akademi University, FI-20014, Turku, Finland.
authors.forename: Dorota
authors.initials: D
authors.lastname: Muth
authors.affiliation: Turku Centre for Biotechnology, University of Turku and Åbo Akademi University, FI-20014, Turku, Finland.
authors.forename: Garry L
authors.initials: GL
authors.lastname: Corthals
authors.affiliation: Department of Biochemistry, Molecular Plant Biology, University of Turku, FI-20014, Turku, Finland.
authors.forename: Saijaliisa
authors.initials: S
authors.lastname: Kangasjärvi
mesh_terms: D000154:Aconitate Hydratase / Q000378:metabolism*; D000595:Amino Acid Sequence; D017360:Arabidopsis / Q000187:drug effects / Q000201:enzymology*; D029681:Arabidopsis Proteins / Q000378:metabolism*; D003593:Cytoplasm / Q000201:enzymology*; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005453:Fluorescence; D006861:Hydrogen Peroxide / Q000378:metabolism; D008928:Mitochondria / Q000187:drug effects / Q000201:enzymology; D024101:Mitochondrial Proteins / Q000037:antagonists & inhibitors / Q000378:metabolism*; D008969:Molecular Sequence Data; D009154:Mutation / Q000235:genetics; D010088:Oxidoreductases / Q000037:antagonists & inhibitors / Q000378:metabolism*; D010455:Peptides / Q000737:chemistry; D010766:Phosphorylation / Q000187:drug effects; D018515:Plant Leaves / Q000187:drug effects / Q000201:enzymology / Q000378:metabolism; D010940:Plant Proteins / Q000037:antagonists & inhibitors / Q000378:metabolism*; D011485:Protein Binding / Q000187:drug effects; D054648:Protein Phosphatase 2 / Q000378:metabolism*; D000099188:Alternative Oxidase
chemical_list: D000154:Aconitate Hydratase; D029681:Arabidopsis Proteins; D004791:Enzyme Inhibitors; D006861:Hydrogen Peroxide; D024101:Mitochondrial Proteins; D010088:Oxidoreductases; D010455:Peptides; D010940:Plant Proteins; D054648:Protein Phosphatase 2; D000099188:Alternative Oxidase; C489810:type 2A protein serine-threonine phosphatase 55 kDa B, Arabidopsis
keywords: alternative oxidase; multiple/selected reaction monitoring (M/SRM); protein phosphatase 2A; proteomics; reactive oxygen species (ROS) signalling