Insights into topology and membrane interaction characteristics of plastoglobule-localized AtFBN1a and AtLOX2

Espinoza‐Corral, Roberto; Herrera-Tequia, Andres; Lundquist, Peter K.

doi:10.1080/15592324.2021.1945213

“…Our discovery that the AH insert of AtFBN1a is responsible for direct interaction with plastoglobules is consistent with our previous study in which we used protease shaving of isolated plastoglobules to map exposed and protected regions of the protein (79). This work suggested a tryptic cleavage site between the α-helical pair and the β-barrel which, together with phosphosites on either side of the α-helical pair identified from publicly available phosphoproteomic datasets, led us to propose that the α-helical pair is positioned distal to the plastoglobule surface and the AH insert in contact with the plastoglobule.…”

Section: Discussionsupporting

confidence: 91%

An amphipathic helix drives interaction of Fibrillins with plastoglobule lipid droplets

Shivaiah,

Boren,

Tequia-Herrera

et al. 2023

Preprint

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Plastoglobule lipid droplets of chloroplasts serve complex roles affecting plant development, stress tolerance and photosynthesis. They harbor a set of approximately 42 proteins that collectively dictate plastoglobule functions. Due to the monolayer structure of plastoglobules which encompass a neutral lipid core, these proteins must associate monotopically on the plastoglobule surface. However, targeting determinants have not been identified for plastoglobule proteins, and the protein-membrane interaction mechanisms that establish the plastoglobule proteome remain unclear. Here, we demonstrate that plastoglobule-localized Fibrillins harbor an amphipathic helix at the lip of their β-barrel that is necessary for proper plastoglobule association. Molecular dynamics simulations support the specific interaction of the amphipathic helix of AtFBN1a with membranes rich in lipid packing defects which are expected to be especially prevalent on the tightly curved surface of plastoglobules. Introduction of one of the amphipathic helices into stromal-or thylakoid-localized FBNs was ineffective at redirecting the proteins to plastoglobules, likely due to endogenous protein-protein interactions that override the influence of the amphipathic helix. Proteomic analyses indicate AtFBN1a influences the plastoglobule proteome through outcompeting and recruiting specific proteins. We also demonstrate that the plastoglobule-localized FBNs, AtFBN1a and AtFBN7a, bind unsaturated fatty acids, particularly C18:1, and that elimination of the amphipathic helix suppresses fatty acid binding in AtFBN1a, but promotes fatty acid binding in AtFBN7a. Predicted amphipathic helices can be identified on two-thirds of plastoglobule proteins, indicating the use of amphipathic helices may be a general mechanism by which proteins selectively associate with plastoglobules.

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“…LOXs participate in fatty acid catabolism during the disassembly of the thylakoid membranes during the chloroplast to chromoplast transition [ 45 ]. Moreover, previous studies propose a model in which the C-terminal PLAT (for p olycystin-1, l ipoxygenase and a lpha t oxin) domain may be responsible for LOX association with PG [ 46 , 47 ]. Another intriguing candidate is MenG that is involved in phylloquinone biosynthesis [ 39 ].…”

Section: Discussionmentioning

confidence: 99%

Chromoplast plastoglobules recruit the carotenoid biosynthetic pathway and contribute to carotenoid accumulation during tomato fruit maturation

Zita

¹

,

Bressoud

²

,

Glauser

³

et al. 2022

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Tomato (Solanum lycopersicum) fruit maturation is associated with a developmental transition from chloroplasts (in mature green fruit) to chromoplasts (in red fruit). The hallmark red color of ripe tomatoes is due to carotenogenesis and accumulation of the red carotenoid lycopene inside chromoplasts. Plastoglobules (PG) are lipid droplets in plastids that are involved in diverse lipid metabolic pathways. In tomato, information on the possible role of PG in carotogenesis and the PG proteome is largely lacking. Here, we outline the role of PG in carotenogenesis giving particular attention to tomato fruit PG proteomes and metabolomes. The proteome analysis revealed the presence of PG-typical FBNs, ABC1K-like kinases, and metabolic enzymes, and those were decreased in the PG of tomato chromoplasts compared to chloroplasts. Notably, the complete β-carotene biosynthesis pathway was recruited to chromoplast PG, and the enzymes PHYTOENE SYNTHASE 1 (PSY-1), PHYTOENE DESATURASE (PDS), ZETA-CAROTENE DESATURASE (ZDS), and CAROTENOID ISOMERASE (CRTISO) were enriched up to twelvefold compared to chloroplast PG. We profiled the carotenoid and prenyl lipid changes in PG during the chloroplast to chromoplast transition and demonstrated large increases of lycopene and β-carotene in chromoplast PG. The PG proteome and metabolome are subject to extensive remodeling resulting in high accumulation of lycopene during the chloroplast-to-chromoplast transition. Overall, the results indicate that PGs contribute to carotenoid accumulation during tomato fruit maturation and suggest that they do so by functioning as a biosynthetic platform for carotenogenesis.

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“…Moreover, previous studies propose a model in which the C-terminal PLAT (for polycystin-1, lipoxygenase and alpha toxin) domain may be responsible for LOX association with PG [46,47].…”

Section: Discussionmentioning

confidence: 99%

“…LOXs participate in fatty acid catabolism during the disassembly of the thylakoid membranes during the chloroplast to chromoplast transition [45]. Moreover, previous studies propose a model in which the C-terminal PLAT (for p olycystin-1, lipoxygenase and a lpha toxin) domain may be responsible for LOX association with PG [46, 47]. Another intriguing candidate is MenG that is involved in phylloquinone biosynthesis [39].…”

Section: Discussionmentioning

confidence: 99%

Chromoplast plastoglobules recruit the carotenoid biosynthetic pathway and contribute to carotenoid accumulation during tomato fruit maturation

Zita

¹

,

Bressoud

²

,

Glauser

³

et al. 2022

Preprint

View full text Add to dashboard Cite

Tomato (Solanum lycopersicum) fruit maturation is associated with a developmental transition from chloroplasts (in mature green fruit) to chromoplasts (in red fruit). The hallmark red color of ripe tomatoes is due to carotenogenesis and accumulation of the red carotenoid lycopene inside chromoplasts. Plastoglobules (PG) are lipid droplets in plastids that are involved in diverse lipid metabolic pathways. In tomato, information on the possible role of PG in carotogenesis and the PG proteome is largely lacking. Here, we outline the role of PG in carotenogenesis giving particular attention to tomato fruit PG proteomes and metabolomes. The proteome analysis revealed the presence of PG-typical FBNs, ABC1K-like kinases, and metabolic enzymes, and those were decreased in the PG of tomato chromoplasts compared to chloroplasts. Notably, the complete β-carotene biosynthesis pathway was recruited to chromoplast PG, and the enzymes PHYTOENE SYNTHASE 1 (PSY-1), PHYTOENE DESATURASE (PDS), ZETA-CAROTENE DESATURASE (ZDS), and CAROTENOID ISOMERASE (CRTISO) were enriched up to twelvefold compared to chloroplast PG. We profiled the carotenoid and prenyl lipid changes in PG during the chloroplast to chromoplast transition and demonstrated large increases of lycopene and β-carotene in chromoplast PG. The PG proteome and metabolome are subject to extensive remodeling resulting in high accumulation of lycopene during the chloroplast-to-chromoplast transition. Overall, the results indicate that PGs contribute to carotenoid accumulation during tomato fruit maturation and suggest that they do so by functioning as a biosynthetic platform for carotenogenesis.

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Insights into topology and membrane interaction characteristics of plastoglobule-localized AtFBN1a and AtLOX2

Cited by 6 publications

References 22 publications

An amphipathic helix drives interaction of Fibrillins with plastoglobule lipid droplets

An amphipathic helix drives interaction of Fibrillins with plastoglobule lipid droplets

Chromoplast plastoglobules recruit the carotenoid biosynthetic pathway and contribute to carotenoid accumulation during tomato fruit maturation

Chromoplast plastoglobules recruit the carotenoid biosynthetic pathway and contribute to carotenoid accumulation during tomato fruit maturation

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