Presentation Information
[1ENZ-19]Bioconversion of glucose and carbon dioxide into 4-hydroxybutyrate-containing polyesters through a novel pathway applying archaeal atypical dehydratase
○Toshiaki Fukui1, Kai Hee Huong1, Shizuru Ishihara1, Izumi Orita1 (1. Institute of Science Tokyo (Japan))
Keywords:
4-hydroxybutyryl-CoA dehydratase,polyhydroxyalkanoate,hydrogen-oxidizing bacteria,Cupriavidus necator,CO2 utilization
[Purpose]
Polyhydroxyalkanoates (PHAs) are produced by a wide variety of bacteria as intracellular carbon- and energy-storage materials. As the bacterial PHAs are bio-based biodegradable polymers, they have drawn increased attention as possible alternatives for petroleum-based one. Unlike the most abundant poly[(R)-3-hydroxybutyrate] [P(3HB)], the copolyesters of (R)-3-hydroxybutyrate with 4-hydroxybutyrate [P(3HB-co-4HB)] is a practical kind of PHAs exhibiting high flexibility as well as high degradability even in marine environments. This study focused on production of the PHA copolymer from renewable feedstocks by recombinant bacterial strains employing an unique archaeal enzyme.
[Results and Discussion]
4HB-CoA dehydratase (4HcD), catalyzing radical-based atypical dehydration/hydration, is one of enzymes difficult to be used in general biotechnological applications due to high sensitivity to reactive oxygen. Here we disclose a new energy-conserving pathway for 4HB-CoA generation from glucose and CO2 by expressing an oxygen-tolerant novel 4HcD derived from ammonia-oxidizing aerobic archaeon. The enzyme complements the missing reaction of crotonyl-CoA to 4HB-CoA in the PHA-producing Cupriavidus necator (Ralstonia eutropha) H16, which facilitated the biosynthesis of P(3HB-co-4HB) copolymer under low-aerobic conditions. The rewiring of the short-chain-acyl-CoA metabolisms in the host cells as well as modifications of the 4hcd gene led to significant increase in 4HB fraction. The use of the hydrogen-oxidizing C. necator as a host strain enabled production of the useful copolyester from CO2 and H2. The results in this study highlights the feasibility of hydrogen-oxidizing bacteria equipped with unique archaeal enzyme in biological carbon capture and utilization.
[Conclusion]
This work provides a practical example that C. necator can be used as a chassis to accommodate exogenous genes encoding unique enzymes for novel biosynthesis pathways and well-positioned its significant impact in current and future industrial biomanufacturing.
Polyhydroxyalkanoates (PHAs) are produced by a wide variety of bacteria as intracellular carbon- and energy-storage materials. As the bacterial PHAs are bio-based biodegradable polymers, they have drawn increased attention as possible alternatives for petroleum-based one. Unlike the most abundant poly[(R)-3-hydroxybutyrate] [P(3HB)], the copolyesters of (R)-3-hydroxybutyrate with 4-hydroxybutyrate [P(3HB-co-4HB)] is a practical kind of PHAs exhibiting high flexibility as well as high degradability even in marine environments. This study focused on production of the PHA copolymer from renewable feedstocks by recombinant bacterial strains employing an unique archaeal enzyme.
[Results and Discussion]
4HB-CoA dehydratase (4HcD), catalyzing radical-based atypical dehydration/hydration, is one of enzymes difficult to be used in general biotechnological applications due to high sensitivity to reactive oxygen. Here we disclose a new energy-conserving pathway for 4HB-CoA generation from glucose and CO2 by expressing an oxygen-tolerant novel 4HcD derived from ammonia-oxidizing aerobic archaeon. The enzyme complements the missing reaction of crotonyl-CoA to 4HB-CoA in the PHA-producing Cupriavidus necator (Ralstonia eutropha) H16, which facilitated the biosynthesis of P(3HB-co-4HB) copolymer under low-aerobic conditions. The rewiring of the short-chain-acyl-CoA metabolisms in the host cells as well as modifications of the 4hcd gene led to significant increase in 4HB fraction. The use of the hydrogen-oxidizing C. necator as a host strain enabled production of the useful copolyester from CO2 and H2. The results in this study highlights the feasibility of hydrogen-oxidizing bacteria equipped with unique archaeal enzyme in biological carbon capture and utilization.
[Conclusion]
This work provides a practical example that C. necator can be used as a chassis to accommodate exogenous genes encoding unique enzymes for novel biosynthesis pathways and well-positioned its significant impact in current and future industrial biomanufacturing.
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