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Plant Lipid Droplets and Their Associated Proteins: Potential for Rapid Advances.
Plant Physiol. 2018 03; 176(3):1894-1918.PP

Abstract

Cytoplasmic lipid droplets (LDs) of neutral lipids (triacylglycerols [TAGs], sterylesters, etc.) are reserves of high-energy metabolites and other constituents for future needs. They are present in diverse cells of eukaryotes and prokaryotes. An LD has a core of neutral lipids enclosed with a monolayer of phospholipids and proteins, which play structural and/or metabolic roles. During the past 3 decades, studies of LDs in diverse organisms have blossomed after they were found to be involved in prevalent human diseases and industrial uses. LDs in plant seeds were studied before those in mammals and microbes, and the latter studies have since moved forward. Plant LDs carry a hallmark protein called oleosin, which has a long hydrophobic hairpin penetrating the TAG core and stabilizing the LD. The oleosin gene first appeared in green algae and has evolved in enhancing promoter strength, tandem repeats, and/or expression specificity, leading to the appearance of new LD organelles, such as tapetosomes in Brassicaceae. The synthesis of LDs occurs with TAG-synthesizing enzymes on the endoplasmic reticulum (ER), and nascent TAGs are sequestered in the acyl moiety region between the bilayers of phospholipids, which results in ER-LD swelling. Oleosin is synthesized on the cytosol side of the ER and extracts the LD from the ER-LD to cytosol. This extraction of LD to the cytosol is controlled solely by the innate properties of oleosin, and modified oleosin can redirect the LD to the ER lumen and then vacuoles. The breakdown of LDs requires lipase associating with core retromer and binding to peroxisomes, which then send the enzyme to LDs via tubular extensions. Two groups of LD-associated proteins, caleosin/dioxygenase/steroleosin and LD/oil body-associated proteins, participate in cellular stress defenses via enzymic activities and binding, respectively. The surface of LDs in all plant cells may be an inert refuge for these and other proteins, which exert functions on diverse cell components. Oleosin-LDs have been explored for commercial applications; successes in their uses will rely on overcoming conceptual and technical difficulties.

Authors+Show Affiliations

Department of Botany and Plant Sciences, Center for Plant Cell Biology, University of California, Riverside, California 92521 anthony.huang@ucr.edu.

Pub Type(s)

Journal Article
Research Support, Non-U.S. Gov't
Research Support, U.S. Gov't, Non-P.H.S.
Review

Language

eng

PubMed ID

29269574

Citation

Huang, Anthony H C.. "Plant Lipid Droplets and Their Associated Proteins: Potential for Rapid Advances." Plant Physiology, vol. 176, no. 3, 2018, pp. 1894-1918.
Huang AHC. Plant Lipid Droplets and Their Associated Proteins: Potential for Rapid Advances. Plant Physiol. 2018;176(3):1894-1918.
Huang, A. H. C. (2018). Plant Lipid Droplets and Their Associated Proteins: Potential for Rapid Advances. Plant Physiology, 176(3), 1894-1918. https://doi.org/10.1104/pp.17.01677
Huang AHC. Plant Lipid Droplets and Their Associated Proteins: Potential for Rapid Advances. Plant Physiol. 2018;176(3):1894-1918. PubMed PMID: 29269574.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Plant Lipid Droplets and Their Associated Proteins: Potential for Rapid Advances. A1 - Huang,Anthony H C, Y1 - 2017/12/21/ PY - 2017/11/20/received PY - 2017/12/10/accepted PY - 2017/12/23/pubmed PY - 2019/1/10/medline PY - 2017/12/23/entrez SP - 1894 EP - 1918 JF - Plant physiology JO - Plant Physiol VL - 176 IS - 3 N2 - Cytoplasmic lipid droplets (LDs) of neutral lipids (triacylglycerols [TAGs], sterylesters, etc.) are reserves of high-energy metabolites and other constituents for future needs. They are present in diverse cells of eukaryotes and prokaryotes. An LD has a core of neutral lipids enclosed with a monolayer of phospholipids and proteins, which play structural and/or metabolic roles. During the past 3 decades, studies of LDs in diverse organisms have blossomed after they were found to be involved in prevalent human diseases and industrial uses. LDs in plant seeds were studied before those in mammals and microbes, and the latter studies have since moved forward. Plant LDs carry a hallmark protein called oleosin, which has a long hydrophobic hairpin penetrating the TAG core and stabilizing the LD. The oleosin gene first appeared in green algae and has evolved in enhancing promoter strength, tandem repeats, and/or expression specificity, leading to the appearance of new LD organelles, such as tapetosomes in Brassicaceae. The synthesis of LDs occurs with TAG-synthesizing enzymes on the endoplasmic reticulum (ER), and nascent TAGs are sequestered in the acyl moiety region between the bilayers of phospholipids, which results in ER-LD swelling. Oleosin is synthesized on the cytosol side of the ER and extracts the LD from the ER-LD to cytosol. This extraction of LD to the cytosol is controlled solely by the innate properties of oleosin, and modified oleosin can redirect the LD to the ER lumen and then vacuoles. The breakdown of LDs requires lipase associating with core retromer and binding to peroxisomes, which then send the enzyme to LDs via tubular extensions. Two groups of LD-associated proteins, caleosin/dioxygenase/steroleosin and LD/oil body-associated proteins, participate in cellular stress defenses via enzymic activities and binding, respectively. The surface of LDs in all plant cells may be an inert refuge for these and other proteins, which exert functions on diverse cell components. Oleosin-LDs have been explored for commercial applications; successes in their uses will rely on overcoming conceptual and technical difficulties. SN - 1532-2548 UR - https://www.unboundmedicine.com/medline/citation/29269574/Plant_Lipid_Droplets_and_Their_Associated_Proteins:_Potential_for_Rapid_Advances_ L2 - http://www.plantphysiol.org/lookup/pmidlookup?view=long&pmid=29269574 DB - PRIME DP - Unbound Medicine ER -