Synthesis of Polyesters III: Acyltransferase as Catalyst

Hiroe, Ayaka; Chek, Min Fey; Hakoshima, Toshio; Sudesh, Kumar; Taguchi, Seiichi

doi:10.1007/978-981-13-3813-7_7

Cited by 4 publications

(4 citation statements)

References 77 publications

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“…The previously reported partial crystal structure, however, disclosed limited information on its catalytic mechanism. Two major models of catalytic mechanisms for PhaC were proposed based on their elongation process in PHA biosynthesis (Hiroe et al, 2019 , 2018;Stubbe et al, 2005). One required two catalytic Cys residues for elongation of the substrates though the ping-pong mechanism, which is also known as the non-processive model (Figure S2A), whereas all three reported crystal structures of PhaC dimers showed that the catalytic Cys residues are located too far apart from each other for the elongation process to happen.…”

Section: Introductionmentioning

confidence: 99%

Asymmetric Open-Closed Dimer Mechanism of Polyhydroxyalkanoate Synthase PhaC

et al. 2020

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Biodegradable polyester polyhydroxyalkanoate (PHA) is a promising bioplastic material for industrial use as a replacement for petroleum-based plastics. PHA synthase PhaC forms an active dimer to polymerize acyl moieties from the substrate acyl-coenzyme A (CoA) into PHA polymers. Here we present the crystal structure of the catalytic domain of PhaC from Chromobacterium sp. USM2, bound to CoA. The structure reveals an asymmetric dimer, in which one protomer adopts an open conformation bound to CoA, whereas the other adopts a closed conformation in a CoA-free form. The open conformation is stabilized by the asymmetric dimerization and enables PhaC to accommodate CoA and also to create the product egress path. The bound CoA molecule has its b-mercaptoethanolamine moiety extended into the active site with the terminal SH group close to active center Cys291, enabling formation of the reaction intermediate by acylation of Cys291.

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Section: Introductionmentioning

confidence: 99%

Asymmetric Open-Closed Dimer Mechanism of Polyhydroxyalkanoate Synthase PhaC

et al. 2020

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“…PHA is one of the PNPs generated spontaneously in the bacterial cytoplasm. PHA belongs to the aliphatic polyesters family of biodegradable and biocompatible polymers [ 304 , 305 , 306 ]. PHA is produced spontaneously by some bacteria in the form of nanosized granules under unbalanced growth conditions, such as an excess of carbon source and nutritional limitations, such as nitrogen, oxygen, and phosphorus [ 307 , 308 , 309 ].…”

Section: Biologically Synthesized Biodegradable Polyhydroxyalkanoate-...mentioning

confidence: 99%

Exploring Various Techniques for the Chemical and Biological Synthesis of Polymeric Nanoparticles

et al. 2022

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Nanoparticles (NPs) have remarkable properties for delivering therapeutic drugs to the body’s targeted cells. NPs have shown to be significantly more efficient as drug delivery carriers than micron-sized particles, which are quickly eliminated by the immune system. Biopolymer-based polymeric nanoparticles (PNPs) are colloidal systems composed of either natural or synthetic polymers and can be synthesized by the direct polymerization of monomers (e.g., emulsion polymerization, surfactant-free emulsion polymerization, mini-emulsion polymerization, micro-emulsion polymerization, and microbial polymerization) or by the dispersion of preformed polymers (e.g., nanoprecipitation, emulsification solvent evaporation, emulsification solvent diffusion, and salting-out). The desired characteristics of NPs and their target applications are determining factors in the choice of method used for their production. This review article aims to shed light on the different methods employed for the production of PNPs and to discuss the effect of experimental parameters on the physicochemical properties of PNPs. Thus, this review highlights specific properties of PNPs that can be tailored to be employed as drug carriers, especially in hospitals for point-of-care diagnostics for targeted therapies.

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“…A polymer incorporating lactate and R3HBA residues was produced by Tajima et al (2012) by using an engineered PHA synthase capable of lactate polymerization. An excellent revision of the chemosynthesis of copolymers containing different 3HAs monomers and lactate was recently published (Hiroe et al, 2019). However, a general drawback of these systems so far is the consumption of ATP, specifically to drive the activation of acetate to acetyl-CoA, a molecule that needs to be present on the reaction mixture to act as the CoA donor to yield the hydroxyacyl-CoAs required for the polymerization reaction.…”

Section: Potential Uses Of Polyhydroxyalkanoates and Its Monomersmentioning

confidence: 99%

Beyond Intracellular Accumulation of Polyhydroxyalkanoates: Chiral Hydroxyalkanoic Acids and Polymer Secretion

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Vergara-Fernández

et al. 2020

Front. Bioeng. Biotechnol.

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Polyhydroxyalkanoates (PHAs) are ubiquitous prokaryotic storage compounds of carbon and energy, acting as sinks for reducing power during periods of surplus of carbon source relative to other nutrients. With close to 150 different hydroxyalkanoate monomers identified, the structure and properties of these polyesters can be adjusted to serve applications ranging from food packaging to biomedical uses. Despite its versatility and the intensive research in the area over the last three decades, the market share of PHAs is still low. While considerable rich literature has accumulated concerning biochemical, physiological, and genetic aspects of PHAs intracellular accumulation, the costs of substrates and processing costs, including the extraction of the polymer accumulated in intracellular granules, still hampers a more widespread use of this family of polymers. This review presents a comprehensive survey and critical analysis of the process engineering and metabolic engineering strategies reported in literature aimed at the production of chiral (R)-hydroxycarboxylic acids (RHAs), either from the accumulated polymer or by bypassing the accumulation of PHAs using metabolically engineered bacteria, and the strategies developed to recover the accumulated polymer without using conventional downstream separations processes. Each of these topics, that have received less attention compared to PHAs accumulation, could potentially improve the economy of PHAs production and use. (R)-hydroxycarboxylic acids can be used as chiral precursors, thanks to its easily modifiable functional groups, and can be either produced de-novo or be obtained from recycled PHA products. On the other hand, efficient mechanisms of PHAs release from bacterial cells, including controlled cell lysis and PHA excretion, could reduce downstream costs and simplify the polymer recovery process.

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Synthesis of Polyesters III: Acyltransferase as Catalyst

Cited by 4 publications

References 77 publications

Asymmetric Open-Closed Dimer Mechanism of Polyhydroxyalkanoate Synthase PhaC

Asymmetric Open-Closed Dimer Mechanism of Polyhydroxyalkanoate Synthase PhaC

Exploring Various Techniques for the Chemical and Biological Synthesis of Polymeric Nanoparticles

Beyond Intracellular Accumulation of Polyhydroxyalkanoates: Chiral Hydroxyalkanoic Acids and Polymer Secretion

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