SEIPIN Isoforms Interact with the Membrane-Tethering Protein VAP27-1 for Lipid Droplet Formation

Greer, Michael S.; Cai, Yingqi; Gidda, Satinder K.; Esnay, Nicolas; Kretzschmar, Franziska K.; Seay, Damien; McClinchie, Elizabeth; Ischebeck, Till; Mullen, Robert T.; Dyer, John M.; Chapman, Kent D.

doi:10.1105/tpc.19.00771

Cited by 39 publications

(33 citation statements)

References 65 publications

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“…As an extension of our recent efforts to identify and characterize new LD proteins in plant vegetative (i.e., non-seed) tissues (Horn et al, 2013;Cai et al, 2015;Gidda et al, 2016;Pyc et al, 2017a;Kretzschmar et al, 2018Kretzschmar et al, , 2020Greer et al, 2020), mature Arabidopsis plants were subject to 1 week of drought treatment in order to elicit TAG accumulation and LD proliferation of LDs, as reported previously in drought-stressed plants (reviewed in Xu and Shanklin, 2016;Yang and Benning, 2018;Lu et al, 2020). Consistent with this, we observed a significant increase in the number of LDs stained with the neutral lipid-selective dye BODIPY 493/503 in leaves from drought stress-treated vs. control (i.e., watered) Arabidopsis plants (Supplementary Figure 2).…”

Section: Erd7 Is Enriched With Lds Isolated From Drought-stressed Aramentioning

confidence: 99%

Arabidopsis thaliana EARLY RESPONSIVE TO DEHYDRATION 7 Localizes to Lipid Droplets via Its Senescence Domain

et al. 2021

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Lipid droplets (LDs) are neutral-lipid-containing organelles found in all kingdoms of life and are coated with proteins that carry out a vast array of functions. Compared to mammals and yeast, relatively few LD proteins have been identified in plants, particularly those associated with LDs in vegetative (non-seed) cell types. Thus, to better understand the cellular roles of LDs in plants, a more comprehensive inventory and characterization of LD proteins is required. Here, we performed a proteomics analysis of LDs isolated from drought-stressed Arabidopsis leaves and identified EARLY RESPONSIVE TO DEHYDRATION 7 (ERD7) as a putative LD protein. mCherry-tagged ERD7 localized to both LDs and the cytosol when ectopically expressed in plant cells, and the protein’s C-terminal senescence domain (SD) was both necessary and sufficient for LD targeting. Phylogenetic analysis revealed that ERD7 belongs to a six-member family in Arabidopsis that, along with homologs in other plant species, is separated into two distinct subfamilies. Notably, the SDs of proteins from each subfamily conferred targeting to either LDs or mitochondria. Further, the SD from the ERD7 homolog in humans, spartin, localized to LDs in plant cells, similar to its localization in mammals; although, in mammalian cells, spartin also conditionally localizes to other subcellular compartments, including mitochondria. Disruption of ERD7 gene expression in Arabidopsis revealed no obvious changes in LD numbers or morphology under normal growth conditions, although this does not preclude a role for ERD7 in stress-induced LD dynamics. Consistent with this possibility, a yeast two-hybrid screen using ERD7 as bait identified numerous proteins involved in stress responses, including some that have been identified in other LD proteomes. Collectively, these observations provide new insight to ERD7 and the SD-containing family of proteins in plants and suggest that ERD7 may be involved in functional aspects of plant stress response that also include localization to the LD surface.

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Section: Erd7 Is Enriched With Lds Isolated From Drought-stressed Aramentioning

confidence: 99%

Arabidopsis thaliana EARLY RESPONSIVE TO DEHYDRATION 7 Localizes to Lipid Droplets via Its Senescence Domain

et al. 2021

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“…Recently, the yeast phosphatase Nem1 has also been identified as an interactor of seipin, playing a major role in the recruitment of TAG synthesis enzymes to LD biogenesis sites ( Choudhary et al, 2020 ). In Arabidopsis thaliana , seipins 2 and 3 interact with the vesicle-associated membrane protein (VAMP) -associated protein VAP27, and this interaction proved crucial for LD formation, although the underlying mechanism still needs to be investigated ( Greer et al, 2020 ). A seipin homolog has been identified in P. tricornutum ( Lu et al, 2017 ) and confirmed as an important factor in LD biogenesis as its overexpression leads to TAG accumulation and increased LD formation.…”

Section: Ld Formation a Cell Response To Adapt To A Challenging Envirmentioning

confidence: 99%

Lipid Droplets in Unicellular Photosynthetic Stramenopiles

et al. 2021

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The Heterokonta or Stramenopile phylum comprises clades of unicellular photosynthetic species, which are promising for a broad range of biotechnological applications, based on their capacity to capture atmospheric CO2 via photosynthesis and produce biomolecules of interest. These molecules include triacylglycerol (TAG) loaded inside specific cytosolic bodies, called the lipid droplets (LDs). Understanding TAG production and LD biogenesis and function in photosynthetic stramenopiles is therefore essential, and is mostly based on the study of a few emerging models, such as the pennate diatom Phaeodactylum tricornutum and eustigmatophytes, such as Nannochloropsis and Microchloropsis species. The biogenesis of cytosolic LD usually occurs at the level of the endoplasmic reticulum. However, stramenopile cells contain a complex plastid deriving from a secondary endosymbiosis, limited by four membranes, the outermost one being connected to the endomembrane system. Recent cell imaging and proteomic studies suggest that at least some cytosolic LDs might be associated to the surface of the complex plastid, via still uncharacterized contact sites. The carbon length and number of double bonds of the acyl groups contained in the TAG molecules depend on their origin. De novo synthesis produces long-chain saturated or monounsaturated fatty acids (SFA, MUFA), whereas subsequent maturation processes lead to very long-chain polyunsaturated FA (VLC-PUFA). TAG composition in SFA, MUFA, and VLC-PUFA reflects therefore the metabolic context that gave rise to the formation of the LD, either via an early partitioning of carbon following FA de novo synthesis and/or a recycling of FA from membrane lipids, e.g., plastid galactolipids or endomembrane phosphor- or betaine lipids. In this review, we address the relationship between cytosolic LDs and the complex membrane compartmentalization within stramenopile cells, the metabolic routes leading to TAG accumulation, and the physiological conditions that trigger LD production, in response to various environmental factors.

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“…For example, the enzyme that synthesizes the bulk of TAG in arabidopsis seeds, DIACYLGLYCEROL ACYLTRANSFERASE 1 (DGAT1), has homologs not only in algae of diverse taxonomic affiliations [9] but also animals and fungi [15,16]. The same holds true for seipins, which are described as proteins that have no enzymatic function but are necessary for the proper formation of LDs in mammals [17], yeast [18], and plants [19][20][21]. Although seipins are conserved across eukaryotes, they underwent diversification, and likely subfunctionalization, during plant evolution, splitting up into several clades, particularly in angiosperms (Figure 2A).…”

Section: The Formation Of Lds Is Underpinned By An Ancient Molecularmentioning

confidence: 99%

Ties between Stress and Lipid Droplets Pre-date Seeds

Vries

Ischebeck

2020

Trends in Plant Science

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Seeds were a key evolutionary innovation. These durable structures provide a concerted solution to two challenges on land: dispersal and stress. Lipid droplets (LDs) that act as nutrient storage reservoirs are one of the main cellbiological reasons for seed endurance. Although LDs are key structures in spermatophytes and are especially abundant in seeds, they are found across plants and algae, and increase during stress. Further, the proteins that underpin their form and function often have deep homologs. We propose an evolutionary scenario in which (i) the generation of LDs arose as a mechanism to mediate general drought and desiccation resilience, and (ii) the required protein framework was co-opted by spermatophytes for a seed-specific program. The Formation of LDs Is a Hallmark Stress Response of Green Organisms Cytosolic lipid droplets (LDs, see Glossary) of plants are best known as the subcellular storage compartments of seeds. However, this captures neither the diversity of LD function nor the diversity of photosynthetic organisms in which LDs occur [1,2]. Several recent reviews have highlighted the diverse functions of LDs in plants [1-4], and we focus here on the deep evolutionary roots of the links between stress physiology and LD formation.

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SEIPIN Isoforms Interact with the Membrane-Tethering Protein VAP27-1 for Lipid Droplet Formation

Cited by 39 publications

References 65 publications

Arabidopsis thaliana EARLY RESPONSIVE TO DEHYDRATION 7 Localizes to Lipid Droplets via Its Senescence Domain

Arabidopsis thaliana EARLY RESPONSIVE TO DEHYDRATION 7 Localizes to Lipid Droplets via Its Senescence Domain

Lipid Droplets in Unicellular Photosynthetic Stramenopiles

Ties between Stress and Lipid Droplets Pre-date Seeds

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