Abstract
Lipid droplets (LDs) of seed tissues are storage organelles for triacylglycerols (TAGs) that provide the energy and carbon for seedling establishment. In the major route of LD degradation (lipolysis), TAGs are mobilized by lipases. However, LDs may also be degraded via lipophagy, a type of selective autophagy, which mediates LD delivery to vacuoles or lysosomes. The exact mechanisms of LD degradation and the mobilization of their content in plants remain unresolved. Here, we provide evidence that LDs are degraded via a process morphologically resembling microlipophagy in Arabidopsis (Arabidopsis thaliana) seedlings. We observed the entry and presence of LDs in the central vacuole as well as their breakdown. Moreover, we show co-localization of AUTOPHAGY-RELATED PROTEIN 8b (ATG8b) and LDs during seed germination and localization of lipidated ATG8 (ATG8-PE) to the LD fraction. We further demonstrate that structural LD proteins from the caleosin family, CALEOSIN 1 (CLO1), CALEOSIN 2 (CLO2), and CALEOSIN 3 (CLO3), interact with ATG8 proteins and possess putative ATG8-interacting motifs (AIMs). Deletion of the AIM localized directly before the proline knot disrupts the interaction of CLO1 with ATG8b, suggesting a possible role of this region in the interaction between these proteins. Collectively, we provide insights into LD degradation by microlipophagy in germinating seeds with a particular focus on the role of structural LD proteins in this process.
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Claims 7
Claim · model-written summary
Lipid droplets entered, remained in, and broke down in the central vacuole of Arabidopsis seedlings.
- Taxon
- Arabidopsis (Arabidopsis thaliana)
Arabidopsis thalianae1 - Outcome
- entry and presence of LDs in the central vacuole as well as their breakdowne0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“We observed the entry and presence of LDs in the central vacuole as well as their breakdown.”
e1“Arabidopsis (Arabidopsis thaliana) seedlings”
Claim · model-written summary
ATG8b co-localized with lipid droplets during seed germination.
- Taxon
- Arabidopsis (Arabidopsis thaliana)Arabidopsis thalianae1
- Organ / stage
- seed germinatione0
- Gene
- AUTOPHAGY-RELATED PROTEIN 8b (ATG8b)e0
- Outcome
- co-localization of AUTOPHAGY-RELATED PROTEIN 8b (ATG8b) and LDse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“we show co-localization of AUTOPHAGY-RELATED PROTEIN 8b (ATG8b) and LDs during seed germination”
e1“Arabidopsis (Arabidopsis thaliana) seedlings”
Claim · model-written summary
Lipidated ATG8 localized to the lipid droplet fraction.
- Taxon
- Arabidopsis (Arabidopsis thaliana)Arabidopsis thalianae1
- Gene
- lipidated ATG8 (ATG8-PE)e0
- Outcome
- localization of lipidated ATG8 (ATG8-PE) to the LD fractione0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“localization of lipidated ATG8 (ATG8-PE) to the LD fraction”
e1“Arabidopsis (Arabidopsis thaliana) seedlings”
Claim · model-written summary
CLO1 interacted with ATG8 proteins and had a putative ATG8-interacting motif.
- Taxon
- Arabidopsis (Arabidopsis thaliana)Arabidopsis thalianae1
- Gene
- CALEOSIN 1 (CLO1)e0
- Outcome
- interact with ATG8 proteins and possess putative ATG8-interacting motifs (AIMs)e0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“CALEOSIN 1 (CLO1), CALEOSIN 2 (CLO2), and CALEOSIN 3 (CLO3), interact with ATG8 proteins and possess putative ATG8-interacting motifs (AIMs)”
e1“Arabidopsis (Arabidopsis thaliana) seedlings”
Claim · model-written summary
CLO2 interacted with ATG8 proteins and had a putative ATG8-interacting motif.
- Taxon
- Arabidopsis (Arabidopsis thaliana)Arabidopsis thalianae1
- Gene
- CALEOSIN 2 (CLO2)e0
- Outcome
- interact with ATG8 proteins and possess putative ATG8-interacting motifs (AIMs)e0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“CALEOSIN 1 (CLO1), CALEOSIN 2 (CLO2), and CALEOSIN 3 (CLO3), interact with ATG8 proteins and possess putative ATG8-interacting motifs (AIMs)”
e1“Arabidopsis (Arabidopsis thaliana) seedlings”
Claim · model-written summary
CLO3 interacted with ATG8 proteins and had a putative ATG8-interacting motif.
- Taxon
- Arabidopsis (Arabidopsis thaliana)Arabidopsis thalianae1
- Gene
- CALEOSIN 3 (CLO3)e0
- Outcome
- interact with ATG8 proteins and possess putative ATG8-interacting motifs (AIMs)e0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“CALEOSIN 1 (CLO1), CALEOSIN 2 (CLO2), and CALEOSIN 3 (CLO3), interact with ATG8 proteins and possess putative ATG8-interacting motifs (AIMs)”
e1“Arabidopsis (Arabidopsis thaliana) seedlings”
Claim · model-written summary
Deleting the motif before the proline knot disrupted CLO1 interaction with ATG8b.
- Taxon
- Arabidopsis (Arabidopsis thaliana)Arabidopsis thalianae1
- Treatment
- Deletion of the AIM localized directly before the proline knote0
- Outcome
- interaction of CLO1 with ATG8be0
- Direction
- disruptse0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Deletion of the AIM localized directly before the proline knot disrupts the interaction of CLO1 with ATG8b”
e1“Arabidopsis (Arabidopsis thaliana) seedlings”
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