Publishing type：Research paper (scientific journal)  

DOI： 10.1016/j.polymdegradstab.2024.110975

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Publishing type：Research paper (scientific journal)  

Corresponding author: Yuki Miyahara, Takeharu Tsuge

DOI： 10.1186/s44316-024-00008-9

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Publishing type：Research paper (scientific journal)  

Corresponding author: Yuki Miyahara, Takeharu Tsuge

DOI： 10.3390/bioengineering11050455

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Publishing type：Research paper (scientific journal)  

DOI： 10.1021/acs.biomac.3c01069

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Publisher：CMC出版  

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Publishing type：Research paper (scientific journal)  

DOI： 10.1016/j.mtsust.2023.100577

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Language：Japanese   Publisher：シーエムシー・リサーチ  

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Publishing type：Research paper (scientific journal)  

DOI： 10.3390/microbiolres14040129

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Publishing type：Research paper (scientific journal)  

DOI： 10.1128/aem.01488-23

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Publishing type：Research paper (scientific journal)  

DOI： 10.3390/pr11071901

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Language：Japanese   Publisher：CMC出版  

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Publishing type：Research paper (scientific journal)  

DOI： 10.1016/j.ijbiomac.2022.10.170

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Language：English   Publishing type：Research paper (scientific journal)  

Polyhydroxyalkanoate (PHA) synthases (PhaCs) are key enzymes in PHA polymerization. PhaCs with broad substrate specificity are attractive for synthesizing structurally diverse PHAs. In the PHA family, 3-hydroxybutyrate (3HB)-based copolymers are industrially produced using Class I PhaCs and can be used as practical biodegradable thermoplastics. However, Class I PhaCs with broad substrate specificities are scarce, prompting our search for novel PhaCs. In this study, four new PhaCs from the bacteria Ferrimonas marina, Plesiomonas shigelloides, Shewanella pealeana, and Vibrio metschnikovii were selected via a homology search against the GenBank database, using the amino acid sequence of Aeromonas caviae PHA synthase (PhaCAc), a Class I enzyme with a wide range of substrate specificities, as a template. The four PhaCs were characterized in terms of their polymerization ability and substrate specificity, using Escherichia coli as a host for PHA production. All the new PhaCs were able to synthesize P(3HB) in E. coli with a high molecular weight, surpassing PhaCAc. The substrate specificity of PhaCs was evaluated by synthesizing 3HB-based copolymers with 3-hydroxyhexanoate, 3-hydroxy-4-methylvalerate, 3-hydroxy-2-methylbutyrate, and 3-hydroxypivalate monomers. Interestingly, PhaC from P. shigelloides (PhaCPs) exhibited relatively broad substrate specificity. PhaCPs was further engineered through site-directed mutagenesis, and the variant resulted in an enzyme with improved polymerization ability and substrate specificity.

DOI： 10.3389/fbioe.2023.1114946

PubMed

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Publishing type：Research paper (scientific journal)  

Corresponding author: Yuki Miyahara, Takeharu Tsuge

DOI： 10.3390/bioengineering9100586

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Publishing type：Research paper (scientific journal)  

DOI： 10.1016/j.jbiosc.2022.07.005

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Language：Japanese   Publisher：CMC出版  

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Language：English   Publishing type：Research paper (scientific journal)  

A new polythioester (PTE), poly(3-mercapto-2-methylpropionate) [P(3M2MP)], and its copolymer with 3-hydroxybutyrate (3HB) were successfully biosynthesized from 3-mercapto-2-methylpropionic acid as a structurally-related precursor. This is the fourth PTE of biological origin and the first to be α-methylated. P(3M2MP) was biosynthesized using an engineered Escherichia coli LSBJ, which has a high molecular weight, amorphous structure, and elastomeric properties, reaching 2600% elongation at break. P(3HB-co-3M2MP) copolymers were synthesized by expressing 3HB-supplying enzymes. The copolymers were produced with high content in the cells and showed a high 3M2MP unit incorporation of up to 77.2 wt% and 54.8 mol%, respectively. As the 3M2MP fraction in the copolymer increased, the molecular weight decreased and the polymers became softer, more flexible, and less crystalline, with lower glass transition temperatures and higher elongations at break. The properties of this PTE were distinct from those of previously biosynthesized PTEs, indicating that the range of material properties can be further expanded by introducing α-methylated thioester monomers.

DOI： 10.3390/bioengineering9050228

PubMed

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Publishing type：Research paper (scientific journal)  

DOI： 10.3390/microorganisms10020458

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Publishing type：Research paper (scientific journal)  

DOI： 10.3389/fbioe.2022.829134

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Language：English   Publishing type：Research paper (scientific journal)  

Poly[(R)-3-hydroxybutyrate-co-(R)-3-hydroxyhexanoate] [P(3HB-co-3HHx)] is a practical kind of bacterial polyhydroxyalkanoates (PHAs). A previous study has established an artificial pathway for the biosynthesis of P(3HB-co-3HHx) from structurally unrelated sugars in Ralstonia eutropha, in which crotonyl-CoA carboxylase/reductase (Ccr) and ethylmalonyl-CoA decarboxylase (Emd) are a key combination for generation of butyryl-CoA and the following chain elongation. This study focused on the installation of the artificial pathway into Escherichia coli. The recombinant strain of E. coli JM109 harboring 11 heterologous genes including Ccr and Emd produced P(3HB-co-3HHx) composed of 14 mol% 3HHx with 41 wt% of dry cellular weight from glucose. Further investigations revealed that the C6 monomer (R)-3HHx-CoA was not supplied by (R)-specific reduction of 3-oxohexanoyl-CoA but by (R)-specific hydration of 2-hexenoyl-CoA formed through reverse β-oxidation after the elongation from C4 to C6. While contribution of the reverse β-oxidation to the conversion of the C4 intermediates was very limited, crotonyl-CoA, a precursor of butyryl-CoA, was generated by dehydration of (R)-3HB-CoA. Several modifications previously reported for enhancement of bioproduction in E. coli were examined for the copolyester synthesis. Elimination of the global regulator Cra or PdhR as well as the block of acetate formation resulted in poor PHA synthesis. The strain lacking RNase G accumulated more PHA but with almost no 3HHx unit. Introduction of the phosphite oxidation system for regeneration of NADPH led to copolyester synthesis with the higher cellular content and higher 3HHx composition by two-stage cultivation with phosphite than those in the absence of phosphite.

DOI： 10.3389/fbioe.2022.888973

PubMed

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Publishing type：Research paper (scientific journal)  

DOI： 10.17516/1997-1389-0363

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Publisher：技術情報協会  

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Language：Japanese   Publisher：エヌ・ティー・エス  

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Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.1016/j.ijbiomac.2020.11.083

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Language：English   Publishing type：Research paper (scientific journal)  

Equal contribution: Yuki Miyahara, Romeo Thorbecke, Masahiro Yamamoto

DOI： 10.1038/s41428-020-00409-3

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Publisher：Wiley  

DOI： 10.1002/9783527818310.ch8

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Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.1007/s10529-020-02876-3

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Language：English   Publisher：Biopolymers for Biomedical and Biotechnological Applications  

DOI： 10.1002/9783527818310.ch8

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Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.1002/biot.201900201

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Language：Japanese   Publishing type：Doctoral thesis  

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Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.1016/j.jbiosc.2018.05.026

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Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.1016/j.jbiosc.2015.01.022

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