Enhancement of acetyl-CoA flux for photosynthetic chemical production by pyruvate dehydrogenase complex overexpression in Synechococcus elongatus PCC 7942

Yasutaka Hirokawa, Takeshi Kubo, Yuki Soma, Fumiko Saruta, Taizo Hanai

研究成果: Contribution to journalArticle査読

15 被引用数 (Scopus)

抄録

Genetic manipulation in cyanobacteria enables the direct production of valuable chemicals from carbon dioxide. However, there are still very few reports of the production of highly effective photosynthetic chemicals. Several synthetic metabolic pathways (e.g., isopropanol, acetone, isoprene, and fatty acids) have been constructed by branching from acetyl-CoA and malonyl-CoA, which are key intermediates for photosynthetic chemical production downstream of pyruvate decarboxylation. Recent reports of the absolute determination of cellular metabolites in Synechococcus elongatus PCC 7942 have shown that its acetyl-CoA levels corresponded to about one hundredth of the pyruvate levels. In short, one of the reasons for lower photosynthetic chemical production from acetyl-CoA and malonyl-CoA was the smaller flux to acetyl-CoA. Pyruvate decarboxylation is a primary pathway for acetyl-CoA synthesis from pyruvate and is mainly catalyzed by the pyruvate dehydrogenase complex (PDHc). In this study, we tried to enhance the flux toward acetyl-CoA from pyruvate by overexpressing PDH genes and, thus, catalyzing the conversion of pyruvate to acetyl-CoA via NADH generation. The overexpression of PDH genes cloned from S. elongatus PCC 7942 significantly increased PDHc enzymatic activity and intracellular acetyl-CoA levels in the crude cell extract. Although growth defects were observed in overexpressing strains of PDH genes, the combinational overexpression of PDH genes with the synthetic metabolic pathway for acetate or isopropanol resulted in about 7-fold to 9-fold improvement in its production titer, respectively (9.9 mM, 594.5 mg/L acetate, 4.9 mM, 294.5 mg/L isopropanol). PDH genes overexpression would, therefore, be useful not only for the production of these model chemicals, but also for the production of other chemicals that require acetyl-CoA as a key precursor.

本文言語英語
ページ(範囲)23-30
ページ数8
ジャーナルMetabolic Engineering
57
DOI
出版ステータス出版済み - 1 2020

All Science Journal Classification (ASJC) codes

  • バイオテクノロジー
  • バイオエンジニアリング
  • 応用微生物学とバイオテクノロジー

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