title: Loss of plastoglobule kinases ABC1K1 and ABC1K3 causes conditional degreening, modified prenyl-lipids, and recruitment of the jasmonic acid pathway.
abstract: Plastoglobules (PGs) are plastid lipid-protein particles. This study examines the function of PG-localized kinases ABC1K1 and ABC1K3 in Arabidopsis thaliana. Several lines of evidence suggested that ABC1K1 and ABC1K3 form a protein complex. Null mutants for both genes (abc1k1 and abc1k3) and the double mutant (k1 k3) displayed rapid chlorosis upon high light stress. Also, k1 k3 showed a slower, but irreversible, senescence-like phenotype during moderate light stress that was phenocopied by drought and nitrogen limitation, but not cold stress. This senescence-like phenotype involved degradation of the photosystem II core and upregulation of chlorophyll degradation. The senescence-like phenotype was independent of the EXECUTER pathway that mediates genetically controlled cell death from the chloroplast and correlated with increased levels of the singlet oxygen-derived carotenoid β-cyclocitral, a retrograde plastid signal. Total PG volume increased during light stress in wild type and k1 k3 plants, but with different size distributions. Isolated PGs from k1 k3 showed a modified prenyl-lipid composition, suggesting reduced activity of PG-localized tocopherol cyclase (VTE1), and was consistent with loss of carotenoid cleavage dioxygenase 4. Plastid jasmonate biosynthesis enzymes were recruited to the k1 k3 PGs but not wild-type PGs, while pheophytinase, which is involved in chlorophyll degradation, was induced in k1 k3 and not wild-type plants and was localized to PGs. Thus, the ABC1K1/3 complex contributes to PG function in prenyl-lipid metabolism, stress response, and thylakoid remodeling.
authors.affiliation: Department of Plant Biology, Cornell University, Ithaca, New York 14853, USA.
authors.forename: Peter K
authors.initials: PK
authors.lastname: Lundquist
authors.forename: Anton
authors.initials: A
authors.lastname: Poliakov
authors.forename: Lisa
authors.initials: L
authors.lastname: Giacomelli
authors.forename: Giulia
authors.initials: G
authors.lastname: Friso
authors.forename: Mason
authors.initials: M
authors.lastname: Appel
authors.forename: Ryan P
authors.initials: RP
authors.lastname: McQuinn
authors.forename: Stuart B
authors.initials: SB
authors.lastname: Krasnoff
authors.forename: Elden
authors.initials: E
authors.lastname: Rowland
authors.forename: Lalit
authors.initials: L
authors.lastname: Ponnala
authors.forename: Qi
authors.initials: Q
authors.lastname: Sun
authors.forename: Klaas J
authors.initials: KJ
authors.lastname: van Wijk
mesh_terms: D017360:Arabidopsis / Q000235:genetics / Q000378:metabolism / Q000528:radiation effects; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D053898:Biosynthetic Pathways / Q000235:genetics / Q000528:radiation effects; D002736:Chloroplasts / Q000235:genetics / Q000378:metabolism / Q000528:radiation effects; D003517:Cyclopentanes / Q000378:metabolism*; D004591:Electrophoresis, Polyacrylamide Gel; D015971:Gene Expression Regulation, Enzymologic; D018506:Gene Expression Regulation, Plant; D015151:Immunoblotting; D008027:Light; D013058:Mass Spectrometry / Q000379:methods; D008854:Microscopy, Electron; D046912:Multiprotein Complexes / Q000235:genetics / Q000378:metabolism; D009154:Mutation; D018384:Oxidative Stress / Q000528:radiation effects; D054883:Oxylipins / Q000378:metabolism*; D010858:Pigmentation / Q000235:genetics / Q000528:radiation effects; D018515:Plant Leaves / Q000235:genetics / Q000378:metabolism / Q000528:radiation effects; D011485:Protein Binding; D011494:Protein Kinases / Q000235:genetics / Q000378:metabolism*; D017346:Protein Serine-Threonine Kinases; D040901:Proteomics / Q000379:methods; D020133:Reverse Transcriptase Polymerase Chain Reaction; D020524:Thylakoids / Q000235:genetics / Q000378:metabolism / Q000648:ultrastructure
chemical_list: D029681:Arabidopsis Proteins; D003517:Cyclopentanes; D046912:Multiprotein Complexes; D054883:Oxylipins; C011006:jasmonic acid; D011494:Protein Kinases; C000604980:ABC1K1 protein, Arabidopsis; D017346:Protein Serine-Threonine Kinases