title: Mitochondrial phosphatidylethanolamine level modulates Cyt c oxidase activity to maintain respiration capacity in Arabidopsis thaliana rosette leaves.
abstract: Phosphatidylethanolamine is the predominant phospholipid of the mitochondrial inner membrane. In Arabidopsis, pect1-4 mutants exhibit reduced cellular phosphatidylethanolamine levels owing to reduced CTP:phosphorylethanolamine cytidylyltransferase (PECT; EC 2.7.7.14) activity. Consequently, pect1-4 mutants may have decreased mitochondrial phosphatidylethanolamine levels, thereby affecting respiration capacity. Wild-type and pect1-4 plants grew similarly under a short-day condition until 5 weeks, when pect1-4 leaves had slightly less Chl. Total respiration was comparable between wild-type and pect1-4 leaves at 3 weeks and then increased 2-fold in the wild-type but only 1.1-fold in pect1-4 leaves. Compared with the wild type, the Cyt oxidase pathway capacity was reduced by 36% in pect1-4 leaves at 5 weeks and by 43% in pect1-4 mitochondria in 5-week-old rosette leaves. Maximal Cyt c oxidase (COX) activity was 20% lower in pect1-4 mitochondria than in wild-type mitochondria at 5 weeks despite comparable COX II protein levels in mitochondria at that time. Furthermore, COX II protein levels doubled in both wild-type and pect1-4 mitochondria between 3 and 5 weeks. Phosphatidylethanolamine levels were similar between mitochondria from these plants at 3 weeks and then increased by 6.4% in wild-type mitochondria and decreased by 6.5% in pect1-4 mitochondria by 5 weeks. Phosphatidylcholine levels compensated for the decreases in phosphatidylethanolamine levels. COX activity was lower in pect1-4 mitochondria at 5 weeks, most probably due to reduced phosphatidylethanolamine levels and/or an altered phosphatidylethanolamine:phosphatidylcholine ratio. Thus, PECT1 regulates mitochondrial phosphatidylethanolamine levels, which are important for maintaining respiration capacity in Arabidopsis leaves during prolonged growth under short-day conditions.
authors.affiliation: Laboratory of Plant Molecular Physiology, Division of Life Science, Graduate School of Science and Engineering, Saitama University, Shimo-Okubo 255, Sakura-Ku, Saitama, 338-8570 Japan.
authors.forename: Masumi
authors.initials: M
authors.lastname: Otsuru
authors.forename: Yanbo
authors.initials: Y
authors.lastname: Yu
authors.forename: Junya
authors.initials: J
authors.lastname: Mizoi
authors.forename: Mari
authors.initials: M
authors.lastname: Kawamoto-Fujioka
authors.forename: Jinyin
authors.initials: J
authors.lastname: Wang
authors.forename: Yuki
authors.initials: Y
authors.lastname: Fujiki
authors.forename: Ikuo
authors.initials: I
authors.lastname: Nishida
mesh_terms: D017360:Arabidopsis / Q000201:enzymology / Q000235:genetics / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism; D019069:Cell Respiration; D003576:Electron Transport Complex IV / Q000378:metabolism*; D015151:Immunoblotting; D008928:Mitochondria / Q000378:metabolism*; D009154:Mutation; D009713:Nucleotidyltransferases / Q000235:genetics / Q000378:metabolism; D010101:Oxygen Consumption; D010713:Phosphatidylcholines / Q000378:metabolism; D010714:Phosphatidylethanolamines / Q000378:metabolism*; D017440:Photoperiod; D018515:Plant Leaves / Q000235:genetics / Q000254:growth & development / Q000378:metabolism*; D013997:Time Factors
chemical_list: D029681:Arabidopsis Proteins; D010713:Phosphatidylcholines; D010714:Phosphatidylethanolamines; C483858:phosphatidylethanolamine; D003576:Electron Transport Complex IV; D009713:Nucleotidyltransferases; C518492:Pect1 protein, Arabidopsis
keywords: Arabidopsis; Cyt oxidase pathway; Mitochondria; Respiration capacity