title: The Arabidopsis sn-1-specific mitochondrial acylhydrolase AtDLAH is positively correlated with seed viability.
abstract: Lipid-derived molecules produced by acylhydrolases play important roles in the regulation of diverse cellular functions in plants. In Arabidopsis, the DAD1-like phospholipase A1 family consists of 12 members, all of which possess a lipase 3 domain. In this study, the biochemical and cellular functions of AtDLAH, an Arabidopsis thaliana DAD1-like acylhydrolase, were examined. Bacterially expressed AtDLAH contained phospholipase A1 activity for catalysing the hydrolysis of phospholipids at the sn-1 position. However, AtDLAH displayed an even stronger preference for 1-lysophosphatidylcholine, 1-monodiacylglycerol, and phosphatidic acid, suggesting that AtDLAH is a sn-1-specific acylhydrolase. The AtDLAH gene was highly expressed in young seedlings, and its encoded protein was exclusively localized to the mitochondria. AtDLAH-overexpressing transgenic seeds (35S:AtDLAH) were markedly tolerant to accelerated-ageing treatment and thus had higher germination percentages than wild-type seeds. In contrast, the atdlah loss-of-function knockout mutant seeds were hypersusceptible to accelerated-ageing conditions. The 35S:AtDLAH seeds, as opposed to the atdlah seeds, exhibited a dark red staining pattern following tetrazolium treatment under both normal and accelerated-ageing conditions, suggesting that AtDLAH expression is positively correlated with seed viability. The enhanced viability of 35S:AtDLAH seeds was accompanied by more densely populated epidermal cells, lower levels of accumulated lipid hydroperoxides, and higher levels of polar lipids as compared with wild-type and atdlah mutant seeds. These results suggest that AtDLAH, a mitochondrial-localized sn-1-specific acylhydrolase, plays an important role in Arabidopsis seed viability.
authors.affiliation: Department of Biology, College of Life Science and Biotechnology, Yonsei University, Seoul 120-749, Korea.
authors.forename: Young Sam
authors.initials: YS
authors.lastname: Seo
authors.forename: Eun Yu
authors.initials: EY
authors.lastname: Kim
authors.forename: Woo Taek
authors.initials: WT
authors.lastname: Kim
mesh_terms: D017360:Arabidopsis / Q000201:enzymology / Q000378:metabolism / Q000502:physiology / Q000648:ultrastructure; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D002855:Chromatography, Thin Layer; D018506:Gene Expression Regulation, Plant; D015227:Lipid Peroxidation; D008855:Microscopy, Electron, Scanning; D024101:Mitochondrial Proteins / Q000235:genetics / Q000378:metabolism*; D012639:Seeds / Q000201:enzymology* / Q000378:metabolism / Q000502:physiology* / Q000648:ultrastructure
chemical_list: D029681:Arabidopsis Proteins; D024101:Mitochondrial Proteins