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A cytosolic acyltransferase contributes to triacylglycerol synthesis in sucrose-rescued Arabidopsis seed oil catabolism mutants

Hernández, M. Luisa; Whitehead, Lynne; He, Zhesi; Gazda, Valeria; Gilday, Alison; Kozhevnikova, Ekaterina; Vaistij, Fabián E.; Larson, Tony; Graham, Ian A

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Triacylglycerol (TAG) levels and oil bodies persist in sucrose (Suc)-rescued Arabidopsis (Arabidopsis thaliana) seedlings disrupted in seed oil catabolism. This study set out to establish if TAG levels persist as a metabolically inert pool when downstream catabolism is disrupted, or if other mechanisms, such as fatty acid (FA) recycling into TAG are operating. We show that TAG composition changes significantly in Suc-rescued seedlings compared with that found in dry seeds, with 18:2 and 18:3...[Show more]

dc.contributor.authorHernández, M. Luisa
dc.contributor.authorWhitehead, Lynne
dc.contributor.authorHe, Zhesi
dc.contributor.authorGazda, Valeria
dc.contributor.authorGilday, Alison
dc.contributor.authorKozhevnikova, Ekaterina
dc.contributor.authorVaistij, Fabián E.
dc.contributor.authorLarson, Tony
dc.contributor.authorGraham, Ian A
dc.date.accessioned2015-12-10T23:27:24Z
dc.identifier.issn0310-7841
dc.identifier.urihttp://hdl.handle.net/1885/68207
dc.description.abstractTriacylglycerol (TAG) levels and oil bodies persist in sucrose (Suc)-rescued Arabidopsis (Arabidopsis thaliana) seedlings disrupted in seed oil catabolism. This study set out to establish if TAG levels persist as a metabolically inert pool when downstream catabolism is disrupted, or if other mechanisms, such as fatty acid (FA) recycling into TAG are operating. We show that TAG composition changes significantly in Suc-rescued seedlings compared with that found in dry seeds, with 18:2 and 18:3 accumulating. However, 20:1 FA is not efficiently recycled back into TAG in young seedlings, instead partitioning into the membrane lipid fraction and diacylglycerol. In the lipolysis mutant sugar dependent1and the β-oxidation double mutant acx1acx2 (for acyl-Coenzyme A oxidase), levels of TAG actually increased in seedlings growing on Suc. We performed a transcriptomic study and identified up-regulation of an acyltransferase gene, DIACYLGLYCEROL ACYLTRANSFERASE3 (DGAT3), with homology to a peanut (Arachis hypogaea) cytosolic acyltransferase. The acyl-Coenzyme A substrate for this acyltransferase accumulates in mutants that are blocked in oil breakdown postlipolysis. Transient expression in Nicotiana benthamiana confirmed involvement in TAG synthesis and specificity toward 18:3 and 18:2 FAs. Double-mutant analysis with the peroxisomal ATP-binding cassette transporter mutant peroxisomal ABC transporter1 indicated involvement of DGAT3 in the partitioning of 18:3 into TAG in mutant seedlings growing on Suc. Fusion of the DGAT3 protein with green fluorescent protein confirmed localization to the cytosol of N. benthamiana. This work has demonstrated active recycling of 18:2 and 18:3 FAs into TAG when seed oil breakdown is blocked in a process involving a soluble cytosolic acyltransferase.
dc.publisherCSLI Publications
dc.sourceAustralian Journal of Plant Physiology
dc.subjectKeywords: Arabidopsis protein; diacylglycerol acyltransferase; fatty acid; sucrose; triacylglycerol; vegetable oil; amino acid sequence; Arabidopsis; article; biosynthesis; cytosol; enzymology; gene expression profiling; gene expression regulation; genetics; germin
dc.titleA cytosolic acyltransferase contributes to triacylglycerol synthesis in sucrose-rescued Arabidopsis seed oil catabolism mutants
dc.typeJournal article
local.description.notesImported from ARIES
local.identifier.citationvolume160
dc.date.issued2012
local.identifier.absfor060104 - Cell Metabolism
local.identifier.ariespublicationf5625xPUB1647
local.type.statusPublished Version
local.contributor.affiliationHernández, M. Luisa, Instituto de la Grasa
local.contributor.affiliationWhitehead, Lynne, College of Medicine, Biology and Environment, ANU
local.contributor.affiliationHe, Zhesi, University of York
local.contributor.affiliationGazda, Valeria, University of York
local.contributor.affiliationGilday, Alison, University of York
local.contributor.affiliationKozhevnikova, Ekaterina, University of York
local.contributor.affiliationVaistij, Fabián E., University of York
local.contributor.affiliationLarson, Tony, University of York
local.contributor.affiliationGraham, Ian A, Univeristy of York
local.description.embargo2037-12-31
local.bibliographicCitation.issue1
local.bibliographicCitation.startpage215
local.bibliographicCitation.lastpage225
local.identifier.doi10.1104/pp.112.201541
local.identifier.absseo820499 - Summer Grains and Oilseeds not elsewhere classified
dc.date.updated2016-02-24T08:49:22Z
local.identifier.scopusID2-s2.0-84865837637
local.identifier.thomsonID000308675100021
CollectionsANU Research Publications

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