Expression of cyanobacterial Acyl-ACP reductase elevates the triacylglycerol level in the red alga cyanidioschyzon merolae

Nobuko Sumiya, Yasuko Kawase, Jumpei Hayakawa, Mami Matsuda, Mami Nakamura, Atsuko Era, Kan Tanaka, Akihiko Kondo, Tomohisa Hasunuma, Sousuke Imamura, Shin Ya Miyagishima

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22 Citations (Scopus)

Abstract

Nitrogen starvation is known to induce the accumulation of triacylglycerol (TAG) in many microalgae, and potential use of microalgae as a source of biofuel has been explored. However, nitrogen starvation also stops cellular growth. The expression of cyanobacterial acyl-acyl carrier protein (ACP) reductase in the unicellular red alga Cyanidioschyzon merolae chloroplasts resulted in an accumulation of TAG, which led to an increase in the number and size of lipid droplets while maintaining cellular growth. Transcriptome and metabolome analyses showed that the expression of acyl-ACP reductase altered the activities of several metabolic pathways. The activities of enzymes involved in fatty acid synthesis in chloroplasts, such as acetyl-CoA carboxylase and pyruvate dehydrogenase, were up-regulated, while pyruvate decarboxylation in mitochondria and the subsequent consumption of acetyl-CoA by the tricarboxylic acid (TCA) cycle were down-regulated. Aldehyde dehydrogenase, which oxidizes fatty aldehydes to fatty acids, was also up-regulated in the acyl-ACP reductase expresser. This activation was required for the lipid droplet accumulation and metabolic changes observed in the acyl-ACP reductase expresser. Nitrogen starvation also resulted in lipid droplet accumulation in C. merolae, while cell growth ceased as in the case of other algal species. The metabolic changes that occur upon the expression of acyl-ACP reductase are quite different from those caused by nitrogen starvation. Therefore, there should be a method for further increasing the storage lipid level while still maintaining cell growth that is different from the metabolic response to nitrogen starvation.

Original languageEnglish
Pages (from-to)1962-1980
Number of pages19
JournalPlant and Cell Physiology
Volume56
Issue number10
DOIs
Publication statusPublished - 2015 Jan 8
Externally publishedYes

Keywords

  • Acyl-ACP reductase
  • Aldehyde dehydrogenase
  • CE-MS
  • Microarray
  • Red alga
  • Triacylglycerol

ASJC Scopus subject areas

  • Medicine(all)
  • Physiology
  • Plant Science
  • Cell Biology

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    Sumiya, N., Kawase, Y., Hayakawa, J., Matsuda, M., Nakamura, M., Era, A., Tanaka, K., Kondo, A., Hasunuma, T., Imamura, S., & Miyagishima, S. Y. (2015). Expression of cyanobacterial Acyl-ACP reductase elevates the triacylglycerol level in the red alga cyanidioschyzon merolae. Plant and Cell Physiology, 56(10), 1962-1980. https://doi.org/10.1093/pcp/pcv120