Assessment of the PETase Conformational Changes Induced by Poly(ethylene terephthalate) Binding

Recently, a bacterium strain of Ideonella sakaiensis was identified with the uncommon ability to degrade the poly(ethylene terephthalate) (PET). The PETase from I. sakaiensis strain 201-F6 catalyzes the hydrolysis of PET converting it to mono(2-hydroxyethyl) terephthalic acid (MHET), bis(2-hydroxyethyl)-TPA (BHET), and terephthalic acid (TPA). Despite the potential of this enzyme for mitigation or elimination of environmental contaminants, one of the limitations of the use of PETase for PET degradation is the fact that it acts only at moderate temperature due to its low thermal stability. Besides, molecular details of the main interaction of PET in the active site of PETase remains unclear. Herein, molecular docking and molecular dynamics (MD) simulations were applied to analyze structural changes of PETase induced by PET binding. Results from the essential dynamics revealed that β1-β2 connecting loop is very flexible. This Loop is located far from the active site of PETase and we suggest that it can be considered for mutagenesis in order to increase the thermal stability of PETase. The free energy landscape (FEL) demonstrates that the main change in the transition between the unbounded to the bounded state is associated with β7-α5 connecting loop, where the catalytic residue Asp206 is located. Overall, the present study provides insights into the molecular binding mechanism of PET into the PETase structure and a computational strategy for mapping flexible regions of this enzyme, which can be useful for the engineering of more efficient enzymes for recycling the plastic polymers using biological systems.

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Comparative Study of Structural Changes of Polylactide and Poly(ethylene terephthalate) in the Presence of Trichoderma viride

International Journal of Molecular Sciences ◽

10.3390/ijms22073491 ◽

2021 ◽

Vol 22 (7) ◽

pp. 3491

Author(s):

Grażyna B. Dąbrowska ◽

Zuzanna Garstecka ◽

Ewa Olewnik-Kruszkowska ◽

Grażyna Szczepańska ◽

Maciej Ostrowski ◽

...

Keyword(s):

Structural Changes ◽

Ethylene Terephthalate ◽

Molecular Mechanisms ◽

Blot Hybridization ◽

Trichoderma Viride ◽

Cost Effective ◽

Plastic Pollution ◽

Scanning Calorimetry ◽

Poly Ethylene Terephthalate ◽

Poly Ethylene

Plastic pollution is one of the crucial global challenges nowadays, and biodegradation is a promising approach to manage plastic waste in an environment-friendly and cost-effective way. In this study we identified the strain of fungus Trichoderma viride GZ1, which was characterized by particularly high pectinolytic activity. Using differential scanning calorimetry, Fourier-transform infrared spectroscopy techniques, and viscosity measurements we showed that three-month incubation of polylactide and polyethylene terephthalate in the presence of the fungus lead to significant changes of the surface of polylactide. Further, to gain insight into molecular mechanisms underneath the biodegradation process, western blot hybridization was used to show that in the presence of poly(ethylene terephthalate) (PET) in laboratory conditions the fungus produced hydrophobin proteins. The mycelium adhered to the plastic surface, which was confirmed by scanning electron microscopy, possibly due to the presence of hydrophobins. Further, using atomic force microscopy we demonstrated for the first time the formation of hydrophobin film on the surface of aliphatic polylactide (PLA) and PET by T. viride GZ1. This is the first stage of research that will be continued under environmental conditions, potentially leading to a practical application.

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Thermal stability of surfactants with amino and imido groups in poly(ethylene terephthalate)/clay composites

Journal of Applied Polymer Science ◽

10.1002/app.28431 ◽

2008 ◽

Vol 109 (6) ◽

pp. 4112-4120 ◽

Cited By ~ 11

Author(s):

Xuepei Yuan ◽

Chuncheng Li ◽

Guohu Guan ◽

Yaonan Xiao ◽

Dong Zhang

Keyword(s):

Thermal Stability ◽

Ethylene Terephthalate ◽

Poly Ethylene Terephthalate ◽

Poly Ethylene ◽

Thermal Stability Of

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Development of a targeted gene disruption system in the PET-degrading bacterium Ideonella sakaiensis and its applications to PETase and MHETase genes

Applied and Environmental Microbiology ◽

10.1128/aem.00020-21 ◽

2021 ◽

Author(s):

Shin-ichi Hachisuka ◽

Tarou Nishii ◽

Shosuke Yoshida

Keyword(s):

Terephthalic Acid ◽

Parent Strain ◽

Gene Disruption ◽

Ethylene Terephthalate ◽

Targeted Gene Disruption ◽

Degrading Bacterium ◽

Poly Ethylene Terephthalate ◽

Poly Ethylene ◽

Pet Hydrolase

Poly(ethylene terephthalate) (PET) is a commonly used synthetic plastic; however its non-biodegradability results in a large amount of waste accumulation that has a negative impact on the environment. Recently, a PET-degrading bacterium Ideonella sakaiensis 201-F6 strain was isolated and the enzymes involved in PET-digestion, PET hydrolase (PETase) and mono(2-hydroxyethyl) terephthalic acid (MHET) hydrolase (MHETase), were identified. Despite the great potentials of I. sakaiensis in bioremediation and biorecycling, approaches to studying this bacterium remain limited. In this study, to enable the functional analysis of PETase and MHETase genes in vivo , we have developed a gene disruption system in I. sakaiensis . The pT18 mobsacB -based disruption vector harboring directly connected 5'- and 3'-flanking regions of the target gene for homologous recombination was introduced into I. sakaiensis cells via conjugation. First, we deleted the orotidine 5'-phosphate decarboxylase gene ( pyrF ) from the genome of the wild-type strain, producing the Δ pyrF strain with 5-fluoroorotic acid (5-FOA) resistance. Next, using the Δ pyrF strain as a parent strain, and pyrF as a counterselection marker, we disrupted the genes for PETase and MHETase. The growth of both Δ petase and Δ mhetase strains on terephthalic acid (TPA, one of the PET hydrolytic products) was comparable to that of the parent strain. However, these mutant strains dramatically decreased the growth level on PET to that on no carbon source. Moreover, the Δ petase strain completely abolished PET degradation capacity. These results demonstrate that PETase and MHETase are essential for I. sakaiensis metabolism of PET. IMPORTANCE The poly(ethylene terephthalate) (PET)-degrading bacterium Ideonella sakaiensis possesses two unique enzymes able to serve in PET hydrolysis. PET hydrolase (PETase) hydrolyzes PET into mono(2-hydroxyethyl) terephthalic acid (MHET) and MHET hydrolase (MHETase) hydrolyzes MHET into terephthalic acid (TPA) and ethylene glycol (EG). These enzymes have attracted global attention as they have potential to be used for bioconversion of PET. Compared to many in vitro studies including the biochemical and crystal structure analyses, few in vivo studies have been reported. Here, we developed a targeted gene disruption system in I. sakaiensis , which was then applied for constructing Δ petase and Δ mhetase strains. Growth of these disruptants revealed that PETase is a sole enzyme responsible for PET degradation in I. sakaiensis , while PETase and MHETase play essential roles in its PET assimilation.

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Depolymerization of Poly(ethylene terephthalate) to Terephthalic Acid and Ethylene Glycol in High-temperature Liquid Water

Chemistry Letters ◽

10.1246/cl.2009.268 ◽

2009 ◽

Vol 38 (3) ◽

pp. 268-269 ◽

Cited By ~ 12

Author(s):

Osamu Sato ◽

Eiichi Mine ◽

Mitsumasa Osada ◽

Norihito Hiyoshi ◽

Aritomo Yamaguchi ◽

...

Keyword(s):

High Temperature ◽

Ethylene Glycol ◽

Liquid Water ◽

Terephthalic Acid ◽

Ethylene Terephthalate ◽

Poly Ethylene Terephthalate ◽

Temperature Liquid ◽

Poly Ethylene

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Effect of barium sulfate on thermal stability and crystallization properties of poly(ethylene terephthalate)

Journal of Thermal Analysis and Calorimetry ◽

10.1007/s10973-017-6237-0 ◽

2017 ◽

Vol 129 (2) ◽

pp. 1047-1055 ◽

Cited By ~ 2

Author(s):

Wei Gao ◽

Zhenting Wang ◽

Zhifeng Zhao ◽

Lili Ding ◽

Yanchao Zhu

Keyword(s):

Thermal Stability ◽

Barium Sulfate ◽

Ethylene Terephthalate ◽

Crystallization Properties ◽

Poly Ethylene Terephthalate ◽

Poly Ethylene

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Microwave-assisted esterification step of poly(ethylene terephthalate) (PET) synthesis through ethylene glycol and terephthalic acid

Polymer Bulletin ◽

10.1007/s00289-018-2521-9 ◽

2018 ◽

Vol 76 (6) ◽

pp. 2931-2944 ◽

Cited By ~ 3

Author(s):

Ana Christy Espinosa-López ◽

Carlos Alberto Ávila-Orta ◽

Francisco Javier Medellín-Rodríguez ◽

Pablo González-Morones ◽

Carlos Alberto Gallardo-Vega ◽

...

Keyword(s):

Ethylene Glycol ◽

Terephthalic Acid ◽

Ethylene Terephthalate ◽

Microwave Assisted ◽

Poly Ethylene Terephthalate ◽

Poly Ethylene

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Polyurethane resin derived from polyol of palm olein and recycled poly(ethylene terephthalate)

Pigment & Resin Technology ◽

10.1108/prt-06-2020-0056 ◽

2021 ◽

Vol ahead-of-print (ahead-of-print) ◽

Author(s):

Abbas Ahmad Adamu ◽

Norazilawati Muhamad Sarih ◽

Seng Neon Gan

Keyword(s):

Thermal Stability ◽

Palm Olein ◽

Ethylene Terephthalate ◽

Alkali Resistance ◽

Pet Waste ◽

Content Type ◽

Pet Bottles ◽

Poly Ethylene Terephthalate ◽

Poly Ethylene ◽

Excellent Adhesion

Purpose Poly(ethylene terephthalate) (PET) waste from soft drink bottles was incorporated into palm olein alkyd to produce new polyol for use in polyurethane resins as surface protection on metal surfaces. Design/methodology/approach Alkyd was prepared from palm olein, glycerol and phthalic anhydride. PET underwent simultaneous glycolysis and transesterification reactions with the alkyd. Varying the amount of PET has led to polyols with different viscosities. Polyurethane resins were produced by reacting the polyols with toluene diisocyanate. The resins were coated on mild steel panels and cured. Performances of the cured films were tested. Findings The polyurethanes (PU) resin cured to a harder film with better thermal stability. Films showed excellent adhesion properties, while higher content of PET exhibited higher pencil hardness, better water, salt, acid and alkali resistance. Research limitations/implications Other vegetable oils could also be used. The alkyd structure could be changed by formulation to have different functionality and the ability to incorporate higher amount of PET waste. Rate of glycolysis of PET could be increased by higher amount of ethylene glycol. Practical implications This method has managed to use waste PET in producing new polyol and PU resins. The cured films exhibit good mechanical and chemical properties, as well as excellent adhesion and thermal stability. Social implications The non-biodegradable PET has created environmental pollution problems connected to littering and illegal landfilling. It has become necessary to pay greater attention to recycling PET bottles for obtaining valuable products. Originality/value This approach is different from the earlier reports, where PET was recycled to recover the raw materials.

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