Acyl-CoA binding protein is required for lipid droplet degradation in the diatom Phaeodactylum tricornutum

Ben Leyland, Ekaterina Novichkova, Achintya Kumar Dolui, Denis Jallet, Fayza Daboussi, Bertrand Legeret, Zhongze Li, Yonghua Li-Beisson, Sammy Boussiba, Inna Khozin-Goldberg

Research output: Contribution to journalArticlepeer-review

2 Scopus citations

Abstract

Diatoms (Bacillariophyceae) accumulate neutral storage lipids in lipid droplets during stress conditions, which can be rapidly degraded and recycled when optimal conditions resume. Since nutrient and light availability fluctuate in marine environments, storage lipid turnover is essential for diatom dominance of marine ecosystems. Diatoms have garnered attention for their potential to provide a sustainable source of omega-3 fatty acids. Several independent proteomic studies of lipid droplets isolated from the model oleaginous pennate diatom Phaeodactylum tricornutum have identified a previously uncharacterized protein with an acyl-CoA binding (ACB) domain, Phatrdraft_48778, here referred to as Phaeodactylum tricornutum acyl-CoA binding protein (PtACBP). We report the phenotypic effects of CRISPR-Cas9 targeted genome editing of PtACBP. ptacbp mutants were defective in lipid droplet and triacylglycerol degradation, as well as lipid and eicosapentaenoic acid synthesis, during recovery from nitrogen starvation. Transcription of genes responsible for peroxisomal β-oxidation, triacylglycerol lipolysis, and eicosapentaenoic acid synthesis was inhibited. A lipid-binding assay using a synthetic ACB domain from PtACBP indicated preferential binding specificity toward certain polar lipids. PtACBP fused to eGFP displayed an endomembrane-like pattern, which surrounded the periphery of lipid droplets. PtACBP is likely responsible for intracellular acyl transport, affecting cell division, development, photosynthesis, and stress response. A deeper understanding of the molecular mechanisms governing storage lipid turnover will be crucial for developing diatoms and other microalgae as biotechnological cell factories.

Original languageEnglish
Pages (from-to)958-981
Number of pages24
JournalPlant Physiology
Volume194
Issue number2
DOIs
StatePublished - 1 Feb 2024

ASJC Scopus subject areas

  • Genetics
  • Physiology
  • Plant Science

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