Branched-chain amino acid catabolism impacts triacylglycerol homeostasis in chlamydomonas reinhardtii

Yuanxue Liang, Fantao Kong, Ismael Torres-Romero, Adrien Burlacot, Stéphan Cuine, Bertrand Légeret, Emmanuelle Billon, Yariv Brotman, Saleh Alseekh, Alisdair R. Fernie, Fred Beisson, Gilles Peltier, Yonghua Li-Beisson

Research output: Contribution to journalArticlepeer-review

22 Scopus citations

Abstract

Nitrogen (N) starvation-induced triacylglycerol (TAG) synthesis, and its complex relationship with starch metabolism in algal cells, has been intensively studied; however, few studies have examined the interaction between amino acid metabolism and TAG biosynthesis. Here, via a forward genetic screen for TAG homeostasis, we isolated a Chlamydomonas (Chlamydomonas reinhardtii) mutant (bkdE1a) that is deficient in the E1a subunit of the branched-chain ketoacid dehydrogenase (BCKDH) complex. Metabolomics analysis revealed a defect in the catabolism of branched-chain amino acids in bkdE1a. Furthermore, this mutant accumulated 30% less TAG than the parental strain during N starvation and was compromised in TAG remobilization upon N resupply. Intriguingly, the rate of mitochondrial respiration was 20% to 35% lower in bkdE1a compared with the parental strains. Three additional knockout mutants of the other components of the BCKDH complex exhibited phenotypes similar to that of bkdE1a. Transcriptional responses of BCKDH to different N status were consistent with its role in TAG homeostasis. Collectively, these results indicate that branched-chain amino acid catabolism contributes to TAG metabolism by providing carbon precursors and ATP, thus highlighting the complex interplay between distinct subcellular metabolisms for oil storage in green microalgae.

Original languageEnglish
Pages (from-to)1502-1514
Number of pages13
JournalPlant Physiology
Volume179
Issue number4
DOIs
StatePublished - 1 Apr 2019
Externally publishedYes

ASJC Scopus subject areas

  • Physiology
  • Genetics
  • Plant Science

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