title: Lipid Droplet-Associated Proteins (LDAPs) Are Required for the Dynamic Regulation of Neutral Lipid Compartmentation in Plant Cells.
abstract: Eukaryotic cells compartmentalize neutral lipids into organelles called lipid droplets (LDs), and while much is known about the role of LDs in storing triacylglycerols in seeds, their biogenesis and function in nonseed tissues are poorly understood. Recently, we identified a class of plant-specific, lipid droplet-associated proteins (LDAPs) that are abundant components of LDs in nonseed cell types. Here, we characterized the three LDAPs in Arabidopsis (Arabidopsis thaliana) to gain insight to their targeting, assembly, and influence on LD function and dynamics. While all three LDAPs targeted specifically to the LD surface, truncation analysis of LDAP3 revealed that essentially the entire protein was required for LD localization. The association of LDAP3 with LDs was detergent sensitive, but the protein bound with similar affinity to synthetic liposomes of various phospholipid compositions, suggesting that other factors contributed to targeting specificity. Investigation of LD dynamics in leaves revealed that LD abundance was modulated during the diurnal cycle, and characterization of LDAP misexpression mutants indicated that all three LDAPs were important for this process. LD abundance was increased significantly during abiotic stress, and characterization of mutant lines revealed that LDAP1 and LDAP3 were required for the proper induction of LDs during heat and cold temperature stress, respectively. Furthermore, LDAP1 was required for proper neutral lipid compartmentalization and triacylglycerol degradation during postgerminative growth. Taken together, these studies reveal that LDAPs are required for the maintenance and regulation of LDs in plant cells and perform nonredundant functions in various physiological contexts, including stress response and postgerminative growth.
authors.affiliation: Department of Molecular and Cellular Biology, University of Guelph, Guelph, Ontario, Canada N1G 2W1 (S.K.G., M.P., R.T.M.);United States Department of Agriculture, Agricultural Research Service, United States Arid-Land Agricultural Research Center, Maricopa, Arizona 85138 (S.P., O.Y., J.M.D.);Department of Biological Sciences, Center for Plant Lipid Research, University of North Texas, Denton, Texas 76203 (Y.C., K.D.C.); andSunnybrook Research Institute and Department of Biochemistry, University of Toronto, Toronto, Ontario, Canada M4N 3M5 (P.W., D.W.A.).
authors.forename: Satinder K
authors.identifier: 0000-0002-4722-0006
authors.initials: SK
authors.lastname: Gidda
authors.affiliation: Department of Molecular and Cellular Biology, University of Guelph, Guelph, Ontario, Canada N1G 2W1 (S.K.G., M.P., R.T.M.);United States Department of Agriculture, Agricultural Research Service, United States Arid-Land Agricultural Research Center, Maricopa, Arizona 85138 (S.P., O.Y., J.M.D.);Department of Biological Sciences, Center for Plant Lipid Research, University of North Texas, Denton, Texas 76203 (Y.C., K.D.C.); andSunnybrook Research Institute and Department of Biochemistry, University of Toronto, Toronto, Ontario, Canada M4N 3M5 (P.W., D.W.A.).
authors.forename: Sunjung
authors.initials: S
authors.lastname: Park
authors.affiliation: Department of Molecular and Cellular Biology, University of Guelph, Guelph, Ontario, Canada N1G 2W1 (S.K.G., M.P., R.T.M.);United States Department of Agriculture, Agricultural Research Service, United States Arid-Land Agricultural Research Center, Maricopa, Arizona 85138 (S.P., O.Y., J.M.D.);Department of Biological Sciences, Center for Plant Lipid Research, University of North Texas, Denton, Texas 76203 (Y.C., K.D.C.); andSunnybrook Research Institute and Department of Biochemistry, University of Toronto, Toronto, Ontario, Canada M4N 3M5 (P.W., D.W.A.).
authors.forename: Michal
authors.identifier: 0000-0001-8702-1661
authors.initials: M
authors.lastname: Pyc
authors.affiliation: Department of Molecular and Cellular Biology, University of Guelph, Guelph, Ontario, Canada N1G 2W1 (S.K.G., M.P., R.T.M.);United States Department of Agriculture, Agricultural Research Service, United States Arid-Land Agricultural Research Center, Maricopa, Arizona 85138 (S.P., O.Y., J.M.D.);Department of Biological Sciences, Center for Plant Lipid Research, University of North Texas, Denton, Texas 76203 (Y.C., K.D.C.); andSunnybrook Research Institute and Department of Biochemistry, University of Toronto, Toronto, Ontario, Canada M4N 3M5 (P.W., D.W.A.).
authors.forename: Olga
authors.identifier: 0000-0002-8628-7190
authors.initials: O
authors.lastname: Yurchenko
authors.affiliation: Department of Molecular and Cellular Biology, University of Guelph, Guelph, Ontario, Canada N1G 2W1 (S.K.G., M.P., R.T.M.);United States Department of Agriculture, Agricultural Research Service, United States Arid-Land Agricultural Research Center, Maricopa, Arizona 85138 (S.P., O.Y., J.M.D.);Department of Biological Sciences, Center for Plant Lipid Research, University of North Texas, Denton, Texas 76203 (Y.C., K.D.C.); andSunnybrook Research Institute and Department of Biochemistry, University of Toronto, Toronto, Ontario, Canada M4N 3M5 (P.W., D.W.A.).
authors.forename: Yingqi
authors.identifier: 0000-0002-0357-5809
authors.initials: Y
authors.lastname: Cai
authors.affiliation: Department of Molecular and Cellular Biology, University of Guelph, Guelph, Ontario, Canada N1G 2W1 (S.K.G., M.P., R.T.M.);United States Department of Agriculture, Agricultural Research Service, United States Arid-Land Agricultural Research Center, Maricopa, Arizona 85138 (S.P., O.Y., J.M.D.);Department of Biological Sciences, Center for Plant Lipid Research, University of North Texas, Denton, Texas 76203 (Y.C., K.D.C.); andSunnybrook Research Institute and Department of Biochemistry, University of Toronto, Toronto, Ontario, Canada M4N 3M5 (P.W., D.W.A.).
authors.forename: Peng
authors.initials: P
authors.lastname: Wu
authors.affiliation: Department of Molecular and Cellular Biology, University of Guelph, Guelph, Ontario, Canada N1G 2W1 (S.K.G., M.P., R.T.M.);United States Department of Agriculture, Agricultural Research Service, United States Arid-Land Agricultural Research Center, Maricopa, Arizona 85138 (S.P., O.Y., J.M.D.);Department of Biological Sciences, Center for Plant Lipid Research, University of North Texas, Denton, Texas 76203 (Y.C., K.D.C.); andSunnybrook Research Institute and Department of Biochemistry, University of Toronto, Toronto, Ontario, Canada M4N 3M5 (P.W., D.W.A.).
authors.forename: David W
authors.identifier: 0000-0002-9266-7157
authors.initials: DW
authors.lastname: Andrews
authors.affiliation: Department of Molecular and Cellular Biology, University of Guelph, Guelph, Ontario, Canada N1G 2W1 (S.K.G., M.P., R.T.M.);United States Department of Agriculture, Agricultural Research Service, United States Arid-Land Agricultural Research Center, Maricopa, Arizona 85138 (S.P., O.Y., J.M.D.);Department of Biological Sciences, Center for Plant Lipid Research, University of North Texas, Denton, Texas 76203 (Y.C., K.D.C.); andSunnybrook Research Institute and Department of Biochemistry, University of Toronto, Toronto, Ontario, Canada M4N 3M5 (P.W., D.W.A.).
authors.forename: Kent D
authors.identifier: 0000-0003-0489-3072
authors.initials: KD
authors.lastname: Chapman
authors.affiliation: Department of Molecular and Cellular Biology, University of Guelph, Guelph, Ontario, Canada N1G 2W1 (S.K.G., M.P., R.T.M.);United States Department of Agriculture, Agricultural Research Service, United States Arid-Land Agricultural Research Center, Maricopa, Arizona 85138 (S.P., O.Y., J.M.D.);Department of Biological Sciences, Center for Plant Lipid Research, University of North Texas, Denton, Texas 76203 (Y.C., K.D.C.); andSunnybrook Research Institute and Department of Biochemistry, University of Toronto, Toronto, Ontario, Canada M4N 3M5 (P.W., D.W.A.) john.dyer@ars.usda.gov rtmullen@uoguelph.ca.
authors.forename: John M
authors.identifier: 0000-0001-6215-0053
authors.initials: JM
authors.lastname: Dyer
authors.affiliation: Department of Molecular and Cellular Biology, University of Guelph, Guelph, Ontario, Canada N1G 2W1 (S.K.G., M.P., R.T.M.);United States Department of Agriculture, Agricultural Research Service, United States Arid-Land Agricultural Research Center, Maricopa, Arizona 85138 (S.P., O.Y., J.M.D.);Department of Biological Sciences, Center for Plant Lipid Research, University of North Texas, Denton, Texas 76203 (Y.C., K.D.C.); andSunnybrook Research Institute and Department of Biochemistry, University of Toronto, Toronto, Ontario, Canada M4N 3M5 (P.W., D.W.A.) john.dyer@ars.usda.gov rtmullen@uoguelph.ca.
authors.forename: Robert T
authors.identifier: 0000-0002-6915-7407
authors.initials: RT
authors.lastname: Mullen
mesh_terms: D000595:Amino Acid Sequence; D017360:Arabidopsis / Q000166:cytology* / Q000235:genetics / Q000254:growth & development / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D002451:Cell Compartmentation; D002940:Circadian Rhythm; D017343:Genes, Plant; D000070136:Lipid Droplet Associated Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D066292:Lipid Droplets / Q000378:metabolism; D008055:Lipids / Q000737:chemistry*; D008081:Liposomes / Q000378:metabolism; D010743:Phospholipids / Q000378:metabolism; D059828:Plant Cells / Q000378:metabolism*; D057445:Plant Dormancy; D018515:Plant Leaves / Q000378:metabolism; D030821:Plants, Genetically Modified; D011485:Protein Binding; D012639:Seeds / Q000254:growth & development / Q000378:metabolism; D013312:Stress, Physiological; D013347:Subcellular Fractions / Q000378:metabolism; D013696:Temperature
chemical_list: D029681:Arabidopsis Proteins; D000070136:Lipid Droplet Associated Proteins; D008055:Lipids; D008081:Liposomes; D010743:Phospholipids