Comparative proteomic analysis of mitochondria isolated from Euglena gracilis under aerobic and hypoxic conditions

Shun Tamaki, Kohei Nishino, Takahisa Ogawa, Takanori Maruta, Yoshihiro Sawa, Kazuharu Arakawa, Takahiro Ishikawa

Research output: Contribution to journalArticle

Abstract

The unicellular microalga Euglena gracilis produces wax esters for ATP acquisition under low-oxygen conditions. The regulatory mechanism of wax ester production is not yet understood. Indeed, our previous transcriptomic analysis showed that transcript levels of genes involved in the wax ester synthesis hardly changed under hypoxic conditions, suggesting contribution of post-transcriptional regulation. In this study, we conducted a proteome analysis of E. gracilis mitochondria, as this organelle employs the fatty-acid synthesis pathway under hypoxic conditions. Mitochondria were isolated from E. gracilis SM-ZK strain treated with both aerobic and hypoxic conditions and used for shotgun proteomic analysis. Three independent proteomic analyses succeeded in identifying a total of 714 non-redundant proteins. Of these, 229 were detected in common to all experiments, and 116 were significantly recognized as differentially expressed proteins. GO enrichment analysis suggested dynamic changes in mitochondrial metabolic pathways and redox reactions under aerobic and hypoxic conditions. Protein levels of bifunctional enzymes isocitrate lyase and malate synthase in glyoxylate cycle were 1.35-fold higher under hypoxic conditions. Abundances of the propionyl- CoA synthetic enzymes, succinyl-CoA synthetase and propionyl-CoA carboxylase, were also 1.35- and 1.47-fold higher, respectively, under hypoxic conditions. Protein levels of pyruvate: NADP+ oxidoreductase, a key enzyme for anaerobic synthesis of acetyl-CoA, which serves as a C2 donor for fatty acids, showed a 1.68-fold increase under hypoxic conditions, whereas those of pyruvate dehydrogenase subunits showed a 0.77-0.81-fold decrease. Protein levels of the fatty-acid synthesis enzymes, 3-ketoacyl-CoA thiolase isoforms (KAT1 and KAT2), 3-hydroxyacyl-CoA dehydrogenases, and acyl-CoA dehydrogenase were up-regulated by 1.20- to 1.42-fold in response to hypoxic treatment. Overall, our proteomic analysis revealed that wax ester synthesis-related enzymes are up-regulated at the protein level posttranscriptionally to promote wax ester production in E. gracilis under low-oxygen conditions.

Original languageEnglish
Article numbere0227226
JournalPloS one
Volume14
Issue number12
DOIs
Publication statusPublished - 2019 Jan 1

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Euglena gracilis
Mitochondria
aerobic conditions
anaerobic conditions
Waxes
Proteomics
proteomics
wax esters
mitochondria
Esters
Enzymes
synthesis
Proteins
Fatty Acids
enzymes
proteins
fatty acids
3-Hydroxyacyl CoA Dehydrogenases
Succinate-CoA Ligases
pyruvate dehydrogenase (lipoamide)

ASJC Scopus subject areas

  • Biochemistry, Genetics and Molecular Biology(all)
  • Agricultural and Biological Sciences(all)
  • General

Cite this

Comparative proteomic analysis of mitochondria isolated from Euglena gracilis under aerobic and hypoxic conditions. / Tamaki, Shun; Nishino, Kohei; Ogawa, Takahisa; Maruta, Takanori; Sawa, Yoshihiro; Arakawa, Kazuharu; Ishikawa, Takahiro.

In: PloS one, Vol. 14, No. 12, e0227226, 01.01.2019.

Research output: Contribution to journalArticle

Tamaki, Shun ; Nishino, Kohei ; Ogawa, Takahisa ; Maruta, Takanori ; Sawa, Yoshihiro ; Arakawa, Kazuharu ; Ishikawa, Takahiro. / Comparative proteomic analysis of mitochondria isolated from Euglena gracilis under aerobic and hypoxic conditions. In: PloS one. 2019 ; Vol. 14, No. 12.
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AU - Arakawa, Kazuharu

AU - Ishikawa, Takahiro

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