TY - JOUR
T1 - Expression of cyanobacterial Acyl-ACP reductase elevates the triacylglycerol level in the red alga cyanidioschyzon merolae
AU - Sumiya, Nobuko
AU - Kawase, Yasuko
AU - Hayakawa, Jumpei
AU - Matsuda, Mami
AU - Nakamura, Mami
AU - Era, Atsuko
AU - Tanaka, Kan
AU - Kondo, Akihiko
AU - Hasunuma, Tomohisa
AU - Imamura, Sousuke
AU - Miyagishima, Shin Ya
PY - 2015/1/8
Y1 - 2015/1/8
N2 - 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.
AB - 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.
KW - Acyl-ACP reductase
KW - Aldehyde dehydrogenase
KW - CE-MS
KW - Microarray
KW - Red alga
KW - Triacylglycerol
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U2 - 10.1093/pcp/pcv120
DO - 10.1093/pcp/pcv120
M3 - Article
C2 - 26272551
AN - SCOPUS:84947290064
VL - 56
SP - 1962
EP - 1980
JO - Plant and Cell Physiology
JF - Plant and Cell Physiology
SN - 0032-0781
IS - 10
ER -