A disulfide bridge in the calcium binding site of a polyester hydrolase increases its thermal stability and activity against polyethylene terephthalate

Then, Johannes; Wei, Ren; Oeser, Thorsten; Gerdts, André; Schmidt, Juliane; Barth, Markus; Zimmermann, Wolfgang

doi:10.1002/2211-5463.12053

Cited by 106 publications

(87 citation statements)

References 22 publications

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“…The here presented interdisciplinary approach for the upcycling of PET is initiated by enzymatic cleavage of the polymer. Microbial polyester hydrolases capable of efficiently degrading amorphous or low-crystallinity PET samples 26 at elevated temperatures close to the glasstransition temperature have been found in fungi 27 , thermophilic actinomycetes (e.g., 20,[28][29][30], and in plant compost 31 . Leaf-branch compost cutinase (LCC) is a polyester hydrolase, of which the encoding gene was originally isolated from a plant compost metagenome 31 .…”

Section: Enzymatic Pet Degradationmentioning

confidence: 99%

Bio-upcycling of polyethylene terephthalate

Tiso¹,

Narancic²,

Wei³

et al. 2020

Preprint

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Over 359 million tons of plastics were produced worldwide in 2018, with significant growth expected in the near future, resulting in the global challenge of end-of-life management. The recent identification of enzymes that degrade plastics previously considered non-biodegradable opens up opportunities to steer the plastic recycling industry into the realm of biotechnology.Here, we present the sequential conversion of polyethylene terephthalate (PET) into two types of bioplastics: a medium chain-length polyhydroxyalkanoate (PHA) and a novel bio-based poly(amide urethane) (bio-PU). PET films were hydrolyzed by a thermostable polyester hydrolase yielding 100% terephthalate and ethylene glycol. A terephthalate-degradingPseudomonas was evolved to also metabolize ethylene glycol and subsequently produced PHA.The strain was further modified to secrete hydroxyalkanoyloxy-alkanoates (HAAs), which were used as monomers for the chemo-catalytic synthesis of bio-PU. In short, we present a novel value-chain for PET upcycling, adding technological flexibility to the global challenge of endof-life management of plastics.

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Section: Enzymatic Pet Degradationmentioning

confidence: 99%

Bio-upcycling of polyethylene terephthalate

Tiso¹,

Narancic²,

Wei³

et al. 2020

Preprint

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“…Through site-directed mutagenesis of the active site, cutinases exhibit higher hydrolysis activity 11 , 12 . Moreover, the introduction of Ca 2+ or Mg 2+ ions to esterases 13 or the addition of disulfide bonds to esterases 14 improves the thermal stability of the enzymes, leading to enhanced PET degradability. Recently, a dual enzyme system consisting of Tf cut2 from T. fusca KW3 and LC cutinase 15 or lipase from C. antarctica and cutinase from Humicola insolens 16 was found to have synergistic effects.…”

Section: Introductionmentioning

confidence: 99%

Structural insight into molecular mechanism of poly(ethylene terephthalate) degradation

et al. 2018

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Plastics, including poly(ethylene terephthalate) (PET), possess many desirable characteristics and thus are widely used in daily life. However, non-biodegradability, once thought to be an advantage offered by plastics, is causing major environmental problem. Recently, a PET-degrading bacterium, Ideonella sakaiensis, was identified and suggested for possible use in degradation and/or recycling of PET. However, the molecular mechanism of PET degradation is not known. Here we report the crystal structure of I. sakaiensis PETase (IsPETase) at 1.5 Å resolution. IsPETase has a Ser–His-Asp catalytic triad at its active site and contains an optimal substrate binding site to accommodate four monohydroxyethyl terephthalate (MHET) moieties of PET. Based on structural and site-directed mutagenesis experiments, the detailed process of PET degradation into MHET, terephthalic acid, and ethylene glycol is suggested. Moreover, other PETase candidates potentially having high PET-degrading activities are suggested based on phylogenetic tree analysis of 69 PETase-like proteins.

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“…Significantly, plastic degradation and bacterial growth with PET as the sole carbon source were both shown to occur at near room temperature (30 C) (Yoshida et al, 2016). Other research using different enzymes capable of degrading of PET has focused on using elevated temperatures approaching the glass transition temperature of the plastic (75 C) (Weissman, 2011), which is thought to improve enzymatic access to cleavable bonds (Ronkvist et al, 2009;Sulaiman et al, 2014;Then et al, 2016;Oda et al, 2018;Wei et al, 2019;Tournier et al, 2020).…”

Section: Introductionmentioning

confidence: 99%

The highly crystalline PET found in plastic water bottles does not support the growth of the PETase‐producing bacterium Ideonella sakaiensis

Wallace

Adams

Chafin

et al. 2020

Environ Microbiol Rep

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Summary Ideonella sakaiensis produces an enzyme, PETase, that is capable of hydrolyzing polyethylene terephthalate (PET) plastic. We demonstrate that although I. sakaiensis can grow on amorphous plastic, it does not grow on highly crystalline plastic under otherwise identical conditions. Both amorphous film and amorphous plastic obtained from commercial food containers support the growth of the bacteria, whereas highly crystalline film and the highly crystalline body of a plastic water bottle do not support growth. Highly crystalline PET can be melted and rapidly cooled to make amorphous plastic which then supports bacterial growth, whereas the same plastic can be melted and slowly cooled to make crystalline plastic which does not support growth. We further subject a plastic water bottle to a top‐to‐bottom analysis, finding that only amorphous sections are degraded, namely the finish (threading), the topmost portion of the shoulder which connects to the finish, and the area immediately surrounding the centre of the base. Finally, we use these results to estimate that the percentage of non‐degradable plastic in plastic water bottles ranges from 52% to 82% (depending on size), demonstrating that most of the plastic found in PET water bottles will not be degraded by I. sakaiensis.

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A disulfide bridge in the calcium binding site of a polyester hydrolase increases its thermal stability and activity against polyethylene terephthalate

Cited by 106 publications

References 22 publications

Bio-upcycling of polyethylene terephthalate

Bio-upcycling of polyethylene terephthalate

Structural insight into molecular mechanism of poly(ethylene terephthalate) degradation

The highly crystalline PET found in plastic water bottles does not support the growth of the PETase‐producing bacterium Ideonella sakaiensis

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