1
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Jäckering A, van der Kamp M, Strodel B, Zinovjev K. Influence of Wobbling Tryptophan and Mutations on PET Degradation Explored by QM/MM Free Energy Calculations. J Chem Inf Model 2024. [PMID: 39344272 DOI: 10.1021/acs.jcim.4c00776] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/01/2024]
Abstract
Plastic-degrading enzymes, particularly poly(ethylene terephthalate) (PET) hydrolases, have garnered significant attention in recent years as potential eco-friendly solutions for recycling plastic waste. However, understanding of their PET-degrading activity and influencing factors remains incomplete, impeding the development of uniform approaches for enhancing PET hydrolases for industrial applications. A key aspect of PET hydrolase engineering is optimizing the PET-hydrolysis reaction by lowering the associated free energy barrier. However, inconsistent findings have complicated these efforts. Therefore, our goal is to elucidate various aspects of enzymatic PET degradation by means of quantum mechanics/molecular mechanics (QM/MM) reaction simulations and analysis, focusing on the initial reaction step, acylation, in two thermophilic PET hydrolases, LCC and PES-H1, along with their highly active variants, LCCIG and PES-H1FY. Our findings highlight the impact of semiempirical QM methods on proton transfer energies, affecting the distinction between a two-step reaction involving a metastable tetrahedral intermediate and a one-step reaction. Moreover, we uncovered a concerted conformational change involving the orientation of the PET benzene ring, altering its interaction with the side-chain of the "wobbling" tryptophan from T-stacking to parallel π-π interactions, a phenomenon overlooked in prior research. Our study thus enhances the understanding of the acylation mechanism of PET hydrolases, in particular by characterizing it for the first time for the promising PES-H1FY using QM/MM simulations. It also provides insights into selecting a suitable QM method and a reaction coordinate, valuable for future studies on PET degradation processes.
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Affiliation(s)
- Anna Jäckering
- Institute of Theoretical and Computational Chemistry, Heinrich Heine University, Universitätsstr. 1, 40225 Düsseldorf, Germany
- Institute of Biological Information Processing: Structural Biochemistry (IBI-7), Forschungszentrum Jülich, Wilhelm-Johnen-Straße, 52428 Jülich, Germany
| | - Marc van der Kamp
- School of Biochemistry, University of Bristol, University Walk, Bristol BS8 1TD, United Kingdom
| | - Birgit Strodel
- Institute of Theoretical and Computational Chemistry, Heinrich Heine University, Universitätsstr. 1, 40225 Düsseldorf, Germany
- Institute of Biological Information Processing: Structural Biochemistry (IBI-7), Forschungszentrum Jülich, Wilhelm-Johnen-Straße, 52428 Jülich, Germany
| | - Kirill Zinovjev
- School of Biochemistry, University of Bristol, University Walk, Bristol BS8 1TD, United Kingdom
- Departament de Química Física, Universitat de València, 46100 Burjassot, Spain
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2
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Zhang Y, Hancock WO. Measuring PETase enzyme kinetics by single-molecule microscopy. Biophys J 2024:S0006-3495(24)00628-3. [PMID: 39300753 DOI: 10.1016/j.bpj.2024.09.016] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2024] [Revised: 08/02/2024] [Accepted: 09/17/2024] [Indexed: 09/22/2024] Open
Abstract
Polyethylene terephthalate (PET) is one of the most widely produced man-made polymers and is a significant contributor to microplastics pollution. The environmental and human health impacts of microplastics pollution have motivated a concerted effort to develop microbe- and enzyme-based strategies to degrade PET and similar plastics. A PETase derived from the bacteria Ideonella sakaiensis was previously shown to enzymatically degrade PET, triggering multidisciplinary efforts to improve the robustness and activity of this and other PETases. However, because these enzymes only erode the surface of the insoluble PET substrate, it is difficult to measure standard kinetic parameters, such as kon, koff, and kcat, complicating interpretation of the activity of mutants using traditional enzyme kinetics frameworks. To address this challenge, we developed a single-molecule microscopy assay that quantifies the landing rate and binding duration of quantum dot-labeled PETase enzymes interacting with a surface-immobilized PET film. Wild-type PETase binding durations were well fit by a biexponential with a fast population having a 2.7 s time constant, interpreted as active binding events, and a slow population interpreted as nonspecific binding interactions that last tens of seconds. A previously described hyperactive mutant, S238F/W159H had both a faster apparent on-rate and a slower off-rate than wild-type PETase, potentially explaining its enhanced activity. Because this single-molecule approach provides a more detailed mechanistic picture of PETase enzymatic activity than standard bulk assays, it should aid future efforts to engineer more robust and active PETases to combat global microplastics pollution.
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Affiliation(s)
- Yuwei Zhang
- Department of Biomedical Engineering, Pennsylvania State University, University Park, Pennsylvania
| | - William O Hancock
- Department of Biomedical Engineering, Pennsylvania State University, University Park, Pennsylvania; Department of Chemistry, Pennsylvania State University, University Park, Pennsylvania.
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3
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Yamashita T, Matsumoto T, Yamada R, Ogino H. Display of PETase on the Cell Surface of Escherichia coli Using the Anchor Protein PgsA. Appl Biochem Biotechnol 2024; 196:5471-5483. [PMID: 38165588 DOI: 10.1007/s12010-023-04837-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/19/2023] [Indexed: 01/04/2024]
Abstract
Enzymatic degradation of polyethylene terephthalate (PET) is attracting attention as a new technology because of its mild reaction conditions. However, the cost of purified enzymes is a major challenge for the practical application of this technology. In this study, we attempted to display the surface of the PET-degrading enzyme, PETase, onto Escherichia coli using the membrane anchor, PgsA, from Bacillus subtilis to omit the need for purification of the enzyme. Immunofluorescence staining confirmed that PETase was successfully displayed on the surface of E. coli cells when a fusion of PgsA and PETase was expressed. The surface-displaying E. coli was able to degrade 94.6% of 1 mM bis(2-hydroxyethyl) terephthalate in 60 min, and the PET films were also degraded in trace amounts. These results indicate that PgsA can be used to present active PETase on the cell surface of E. coli. This technique is expected to be applied for efficient PET degradation.
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Affiliation(s)
- Takuma Yamashita
- Department of Chemical Engineering, Osaka Metropolitan University, 1-1 Gakuen-Cho, Naka-Ku, Sakai, Osaka, 599-8531, Japan
| | - Takuya Matsumoto
- Department of Chemical Engineering, Osaka Metropolitan University, 1-1 Gakuen-Cho, Naka-Ku, Sakai, Osaka, 599-8531, Japan.
| | - Ryosuke Yamada
- Department of Chemical Engineering, Osaka Metropolitan University, 1-1 Gakuen-Cho, Naka-Ku, Sakai, Osaka, 599-8531, Japan
| | - Hiroyasu Ogino
- Department of Chemical Engineering, Osaka Metropolitan University, 1-1 Gakuen-Cho, Naka-Ku, Sakai, Osaka, 599-8531, Japan
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4
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Ercolano C, Iacono R, Cafaro V, Pizzo E, Giovannelli D, Feuerriegel G, Streit WR, Strazzulli A, Moracci M. Biochemical Characterisation of Sis: A Distinct Thermophilic PETase with Enhanced NanoPET Substrate Hydrolysis and Thermal Stability. Int J Mol Sci 2024; 25:8120. [PMID: 39125688 PMCID: PMC11311821 DOI: 10.3390/ijms25158120] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2024] [Revised: 07/12/2024] [Accepted: 07/23/2024] [Indexed: 08/12/2024] Open
Abstract
Polyethylene terephthalate (PET) degradation by enzymatic hydrolysis is significant for addressing plastic pollution and fostering sustainable waste management practices. Identifying thermophilic and thermostable PET hydrolases is particularly crucial for industrial bioprocesses, where elevated temperatures may enhance enzymatic efficiency and process kinetics. In this study, we present the discovery of a novel thermophilic and thermostable PETase enzyme named Sis, obtained through metagenomic sequence-based analysis. Sis exhibits robust activity on nanoPET substrates, demonstrating effectiveness at temperatures up to 70 °C and displaying exceptional thermal stability with a melting temperature (Tm) of 82 °C. Phylogenetically distinct from previously characterised PET hydrolases, Sis represents a valuable addition to the repertoire of enzymes suitable for PET degradation.
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Affiliation(s)
- Carmen Ercolano
- Department of Biology, University of Naples Federico II, Complesso Universitario di Monte S. Angelo, Via Cinthia 21, 80126 Naples, Italy; (C.E.); (R.I.); (V.C.); (E.P.); (D.G.); (M.M.)
| | - Roberta Iacono
- Department of Biology, University of Naples Federico II, Complesso Universitario di Monte S. Angelo, Via Cinthia 21, 80126 Naples, Italy; (C.E.); (R.I.); (V.C.); (E.P.); (D.G.); (M.M.)
- National Biodiversity Future Center (NBFC), 90133 Palermo, Italy
| | - Valeria Cafaro
- Department of Biology, University of Naples Federico II, Complesso Universitario di Monte S. Angelo, Via Cinthia 21, 80126 Naples, Italy; (C.E.); (R.I.); (V.C.); (E.P.); (D.G.); (M.M.)
| | - Elio Pizzo
- Department of Biology, University of Naples Federico II, Complesso Universitario di Monte S. Angelo, Via Cinthia 21, 80126 Naples, Italy; (C.E.); (R.I.); (V.C.); (E.P.); (D.G.); (M.M.)
- Centro Servizi Metrologici e Tecnologici Avanzati (CeSMA), University of Naples Federico II, 80126 Naples, Italy
| | - Donato Giovannelli
- Department of Biology, University of Naples Federico II, Complesso Universitario di Monte S. Angelo, Via Cinthia 21, 80126 Naples, Italy; (C.E.); (R.I.); (V.C.); (E.P.); (D.G.); (M.M.)
- National Biodiversity Future Center (NBFC), 90133 Palermo, Italy
- Institute for Marine Biological Resources and Biotechnologies, Italian National Research Council, CNR-IRBIM, 60125 Ancona, Italy
- Department of Marine and Coastal Science, Rutgers University, New Brunswick, NJ 08901, USA
- Marine Chemistry and Geochemistry Department, Woods Hole Oceanographic Institution, Woods Hole, MA 02543, USA
- Earth-Life Science Institute (ELSI), Tokyo Institute of Technology, Tokyo 152-8552, Japan
| | - Golo Feuerriegel
- Department of Microbiology and Biotechnology, University of Hamburg, 22609 Hamburg, Germany; (G.F.); (W.R.S.)
| | - Wolfgang R. Streit
- Department of Microbiology and Biotechnology, University of Hamburg, 22609 Hamburg, Germany; (G.F.); (W.R.S.)
| | - Andrea Strazzulli
- Department of Biology, University of Naples Federico II, Complesso Universitario di Monte S. Angelo, Via Cinthia 21, 80126 Naples, Italy; (C.E.); (R.I.); (V.C.); (E.P.); (D.G.); (M.M.)
- National Biodiversity Future Center (NBFC), 90133 Palermo, Italy
| | - Marco Moracci
- Department of Biology, University of Naples Federico II, Complesso Universitario di Monte S. Angelo, Via Cinthia 21, 80126 Naples, Italy; (C.E.); (R.I.); (V.C.); (E.P.); (D.G.); (M.M.)
- National Biodiversity Future Center (NBFC), 90133 Palermo, Italy
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5
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Charlier C, Gavalda S, Grga J, Perrot L, Gabrielli V, Löhr F, Schörghuber J, Lichtenecker R, Arnal G, Marty A, Tournier V, Lippens G. Exploring the pH dependence of an improved PETase. Biophys J 2024; 123:1542-1552. [PMID: 38664965 PMCID: PMC11213969 DOI: 10.1016/j.bpj.2024.04.026] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2024] [Revised: 03/20/2024] [Accepted: 04/23/2024] [Indexed: 05/12/2024] Open
Abstract
Enzymatic recycling of plastic and especially of polyethylene terephthalate (PET) has shown great potential to reduce its negative impact on our society. PET hydrolases (PETases) have been optimized using rational design and machine learning, but the mechanistic details of the PET depolymerization process remain unclear. Belonging to the carboxylic-ester hydrolase family with a canonical Ser-His-Asp catalytic triad, their observed alkaline pH optimum is generally thought to be related to the protonation state of the catalytic His. Here, we explore this aspect in the context of LCCICCG, an optimized PETase, derived from the leaf-branch compost cutinase enzyme. We use NMR to identify the dominant tautomeric structure of the six histidines. Five show surprisingly low pKa values below 4.0, whereas the catalytic H242 in the active enzyme displays a pKa value that varies from 4.9 to 4.7 when temperatures increase from 30°C to 50°C. Whereas the hydrolytic activity of the enzyme toward a soluble substrate can be modeled by the corresponding protonation/deprotonation curve, an important discrepancy is found when the substrate is the solid plastic. This opens the way to further mechanistic understanding of the PETase activity and underscores the importance of studying the enzyme at the liquid-solid interface.
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Affiliation(s)
- Cyril Charlier
- Toulouse Biotechnology Institute (TBI), University of Toulouse, CNRS, INRAE, INSA Toulouse, Toulouse Cedex, France
| | - Sabine Gavalda
- Carbios, Parc Cataroux - Bâtiment B80, Clermont-Ferrand, France
| | - Jelena Grga
- Toulouse Biotechnology Institute (TBI), University of Toulouse, CNRS, INRAE, INSA Toulouse, Toulouse Cedex, France
| | - Laura Perrot
- Toulouse Biotechnology Institute (TBI), University of Toulouse, CNRS, INRAE, INSA Toulouse, Toulouse Cedex, France
| | - Valeria Gabrielli
- Toulouse Biotechnology Institute (TBI), University of Toulouse, CNRS, INRAE, INSA Toulouse, Toulouse Cedex, France
| | - Frank Löhr
- Institute of Biophysical Chemistry, Center for Biomolecular Magnetic Resonance, Goethe, University Frankfurt, Frankfurt am Main, Germany
| | - Julia Schörghuber
- Institute of Organic Chemistry, University of Vienna, Währingerstraße 38, Vienna, Austria
| | - Roman Lichtenecker
- Institute of Organic Chemistry, University of Vienna, Währingerstraße 38, Vienna, Austria; MAG-LAB, Vienna, Austria
| | - Grégory Arnal
- Carbios, Parc Cataroux - Bâtiment B80, Clermont-Ferrand, France
| | - Alain Marty
- Carbios, Parc Cataroux - Bâtiment B80, Clermont-Ferrand, France
| | | | - Guy Lippens
- Toulouse Biotechnology Institute (TBI), University of Toulouse, CNRS, INRAE, INSA Toulouse, Toulouse Cedex, France.
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6
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Zhang Y, Hancock WO. Measuring PETase enzyme kinetics by single-molecule microscopy. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.04.24.590935. [PMID: 38712273 PMCID: PMC11071475 DOI: 10.1101/2024.04.24.590935] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2024]
Abstract
Polyethylene terephthalate (PET) is one of the most widely produced man-made polymers and is a significant contributor to microplastics pollution. The environmental and human health impacts of microplastics pollution have motivated a concerted effort to develop microbe- and enzyme-based strategies to degrade PET and similar plastics. A PETase derived from the bacteria Ideonella sakaiensis was previously shown to enzymatically degrade PET, triggering multidisciplinary efforts to improve the robustness and activity of this and other PETases. However, because these enzymes only erode the surface of the insoluble PET substrate, it is difficult to measure standard kinetic parameters, such as kon, koff and kcat, complicating interpretation of the activity of mutants using traditional enzyme kinetics frameworks. To address this challenge, we developed a single-molecule microscopy assay that quantifies the landing rate and binding duration of quantum dot-labeled PETase enzymes interacting with a surface-immobilized PET film. Wild-type PETase binding durations were well fit by a biexponential with a fast population having a 2.7 s time constant, interpreted as active binding events, and a slow population interpreted as non-specific binding interactions that last tens of seconds. A previously described hyperactive mutant, S238F/W159H had both a faster on-rate and a slower off-rate than wild-type PETase, potentially explaining its enhanced activity. Because this single-molecule approach provides a more detailed mechanistic picture of PETase enzymatic activity than standard bulk assays, it should aid future efforts to engineer more robust and active PETases to combat global microplastics pollution.
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Affiliation(s)
- Yuwei Zhang
- Department of Biomedical Engineering, Pennsylvania State University, University Park, Pennsylvania, USA
| | - William O. Hancock
- Department of Biomedical Engineering, Pennsylvania State University, University Park, Pennsylvania, USA
- Department of Chemistry, Pennsylvania State University, University Park, Pennsylvania, USA
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7
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Choi J, Kim H, Ahn YR, Kim M, Yu S, Kim N, Lim SY, Park JA, Ha SJ, Lim KS, Kim HO. Recent advances in microbial and enzymatic engineering for the biodegradation of micro- and nanoplastics. RSC Adv 2024; 14:9943-9966. [PMID: 38528920 PMCID: PMC10961967 DOI: 10.1039/d4ra00844h] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2024] [Accepted: 03/19/2024] [Indexed: 03/27/2024] Open
Abstract
This review examines the escalating issue of plastic pollution, specifically highlighting the detrimental effects on the environment and human health caused by microplastics and nanoplastics. The extensive use of synthetic polymers such as polyethylene (PE), polyethylene terephthalate (PET), and polystyrene (PS) has raised significant environmental concerns because of their long-lasting and non-degradable characteristics. This review delves into the role of enzymatic and microbial strategies in breaking down these polymers, showcasing recent advancements in the field. The intricacies of enzymatic degradation are thoroughly examined, including the effectiveness of enzymes such as PETase and MHETase, as well as the contribution of microbial pathways in breaking down resilient polymers into more benign substances. The paper also discusses the impact of chemical composition on plastic degradation kinetics and emphasizes the need for an approach to managing the environmental impact of synthetic polymers. The review highlights the significance of comprehending the physical characteristics and long-term impacts of micro- and nanoplastics in different ecosystems. Furthermore, it points out the environmental and health consequences of these contaminants, such as their ability to cause cancer and interfere with the endocrine system. The paper emphasizes the need for advanced analytical methods and effective strategies for enzymatic degradation, as well as continued research and development in this area. This review highlights the crucial role of enzymatic and microbial strategies in addressing plastic pollution and proposes methods to create effective and environmentally friendly solutions.
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Affiliation(s)
- Jaewon Choi
- Division of Chemical Engineering and Bioengineering, College of Art, Culture and Engineering, Kangwon National University Chuncheon Korea
- Department of Smart Health Science and Technology, Kangwon National University Chuncheon Korea
| | - Hongbin Kim
- Division of Chemical Engineering and Bioengineering, College of Art, Culture and Engineering, Kangwon National University Chuncheon Korea
- Department of Smart Health Science and Technology, Kangwon National University Chuncheon Korea
| | - Yu-Rim Ahn
- Division of Chemical Engineering and Bioengineering, College of Art, Culture and Engineering, Kangwon National University Chuncheon Korea
- Department of Smart Health Science and Technology, Kangwon National University Chuncheon Korea
| | - Minse Kim
- Division of Chemical Engineering and Bioengineering, College of Art, Culture and Engineering, Kangwon National University Chuncheon Korea
- Department of Smart Health Science and Technology, Kangwon National University Chuncheon Korea
| | - Seona Yu
- Division of Chemical Engineering and Bioengineering, College of Art, Culture and Engineering, Kangwon National University Chuncheon Korea
- Department of Smart Health Science and Technology, Kangwon National University Chuncheon Korea
| | - Nanhyeon Kim
- Division of Chemical Engineering and Bioengineering, College of Art, Culture and Engineering, Kangwon National University Chuncheon Korea
- Department of Smart Health Science and Technology, Kangwon National University Chuncheon Korea
| | - Su Yeon Lim
- Division of Chemical Engineering and Bioengineering, College of Art, Culture and Engineering, Kangwon National University Chuncheon Korea
- Department of Smart Health Science and Technology, Kangwon National University Chuncheon Korea
| | - Jeong-Ann Park
- Department of Environmental Engineering, Kangwon National University Chuncheon 24341 Republic of Korea
| | - Suk-Jin Ha
- Division of Chemical Engineering and Bioengineering, College of Art, Culture and Engineering, Kangwon National University Chuncheon Korea
- Department of Smart Health Science and Technology, Kangwon National University Chuncheon Korea
| | - Kwang Suk Lim
- Division of Chemical Engineering and Bioengineering, College of Art, Culture and Engineering, Kangwon National University Chuncheon Korea
- Department of Smart Health Science and Technology, Kangwon National University Chuncheon Korea
| | - Hyun-Ouk Kim
- Division of Chemical Engineering and Bioengineering, College of Art, Culture and Engineering, Kangwon National University Chuncheon Korea
- Department of Smart Health Science and Technology, Kangwon National University Chuncheon Korea
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8
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Naidu G, Nagar N, Poluri KM. Mechanistic Insights into Cellular and Molecular Basis of Protein-Nanoplastic Interactions. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2024; 20:e2305094. [PMID: 37786309 DOI: 10.1002/smll.202305094] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/16/2023] [Revised: 09/07/2023] [Indexed: 10/04/2023]
Abstract
Plastic waste is ubiquitously present across the world, and its nano/sub-micron analogues (plastic nanoparticles, PNPs), raise severe environmental concerns affecting organisms' health. Considering the direct and indirect toxic implications of PNPs, their biological impacts are actively being studied; lately, with special emphasis on cellular and molecular mechanistic intricacies. Combinatorial OMICS studies identified proteins as major regulators of PNP mediated cellular toxicity via activation of oxidative enzymes and generation of ROS. Alteration of protein function by PNPs results in DNA damage, organellar dysfunction, and autophagy, thus resulting in inflammation/cell death. The molecular mechanistic basis of these cellular toxic endeavors is fine-tuned at the level of structural alterations in proteins of physiological relevance. Detailed biophysical studies on such protein-PNP interactions evidenced prominent modifications in their structural architecture and conformational energy landscape. Another essential aspect of the protein-PNP interactions includes bioenzymatic plastic degradation perspective, as the interactive units of plastics are essentially nano-sized. Combining all these attributes of protein-PNP interactions, the current review comprehensively documented the contemporary understanding of the concerned interactions in the light of cellular, molecular, kinetic/thermodynamic details. Additionally, the applicatory, economical facet of these interactions, PNP biogeochemical cycle and enzymatic advances pertaining to plastic degradation has also been discussed.
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Affiliation(s)
- Goutami Naidu
- Department of Biosciences and Bioengineering, Indian Institute of Technology Roorkee, Roorkee, Uttarakhand, 247667, India
| | - Nupur Nagar
- Department of Biosciences and Bioengineering, Indian Institute of Technology Roorkee, Roorkee, Uttarakhand, 247667, India
| | - Krishna Mohan Poluri
- Department of Biosciences and Bioengineering, Indian Institute of Technology Roorkee, Roorkee, Uttarakhand, 247667, India
- Centre for Nanotechnology, Indian Institute of Technology Roorkee, Roorkee, Uttarakhand, 247667, India
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9
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Joho Y, Vongsouthi V, Gomez C, Larsen JS, Ardevol A, Jackson CJ. Improving plastic degrading enzymes via directed evolution. Protein Eng Des Sel 2024; 37:gzae009. [PMID: 38713696 PMCID: PMC11091475 DOI: 10.1093/protein/gzae009] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2023] [Revised: 04/30/2024] [Accepted: 05/05/2024] [Indexed: 05/09/2024] Open
Abstract
Plastic degrading enzymes have immense potential for use in industrial applications. Protein engineering efforts over the last decade have resulted in considerable enhancement of many properties of these enzymes. Directed evolution, a protein engineering approach that mimics the natural process of evolution in a laboratory, has been particularly useful in overcoming some of the challenges of structure-based protein engineering. For example, directed evolution has been used to improve the catalytic activity and thermostability of polyethylene terephthalate (PET)-degrading enzymes, although its use for the improvement of other desirable properties, such as solvent tolerance, has been less studied. In this review, we aim to identify some of the knowledge gaps and current challenges, and highlight recent studies related to the directed evolution of plastic-degrading enzymes.
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Affiliation(s)
- Yvonne Joho
- Manufacturing, Commonwealth Scientific and Industrial Research Organisation, Research Way, Clayton, Victoria 3168, Australia
- Research School of Chemistry, Australian National University, Sullivans Creek Rd, Canberra, ACT 2601, Australia
- CSIRO Advanced Engineering Biology Future Science Platform, GPO Box 1700, Canberra, ACT 2601, Australia
| | - Vanessa Vongsouthi
- Research School of Chemistry, Australian National University, Sullivans Creek Rd, Canberra, ACT 2601, Australia
| | - Chloe Gomez
- Research School of Chemistry, Australian National University, Sullivans Creek Rd, Canberra, ACT 2601, Australia
| | - Joachim S Larsen
- Research School of Chemistry, Australian National University, Sullivans Creek Rd, Canberra, ACT 2601, Australia
- ARC Centre of Excellence for Synthetic Biology, Research School of Chemistry, Australian National University, Sullivans Creek Rd, Canberra, ACT 2601, Australia
| | - Albert Ardevol
- Manufacturing, Commonwealth Scientific and Industrial Research Organisation, Research Way, Clayton, Victoria 3168, Australia
- CSIRO Advanced Engineering Biology Future Science Platform, GPO Box 1700, Canberra, ACT 2601, Australia
| | - Colin J Jackson
- Research School of Chemistry, Australian National University, Sullivans Creek Rd, Canberra, ACT 2601, Australia
- ARC Centre of Excellence for Synthetic Biology, Research School of Chemistry, Australian National University, Sullivans Creek Rd, Canberra, ACT 2601, Australia
- ARC Centre of Excellence for Innovations in Peptide & Protein Science, Research School of Chemistry, Australian National University, Sullivans Creek Rd, Canberra, ACT 2601, Australia
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10
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Burkhardt C, Baruth L, Neele Meyer-Heydecke, Klippel B, Margaryan A, Paloyan A, Panosyan HH, Antranikian G. Mining thermophiles for biotechnologically relevant enzymes: evaluating the potential of European and Caucasian hot springs. Extremophiles 2023; 28:5. [PMID: 37991546 PMCID: PMC10665251 DOI: 10.1007/s00792-023-01321-3] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2023] [Accepted: 10/06/2023] [Indexed: 11/23/2023]
Abstract
The development of sustainable and environmentally friendly industrial processes is becoming very crucial and demanding for the rapid implementation of innovative bio-based technologies. Natural extreme environments harbor the potential for discovering and utilizing highly specific and efficient biocatalysts that are adapted to harsh conditions. This review focuses on extremophilic microorganisms and their enzymes (extremozymes) from various hot springs, shallow marine vents, and other geothermal habitats in Europe and the Caucasus region. These hot environments have been partially investigated and analyzed for microbial diversity and enzymology. Hotspots like Iceland, Italy, and the Azores harbor unique microorganisms, including bacteria and archaea. The latest results demonstrate a great potential for the discovery of new microbial species and unique enzymes that can be explored for the development of Circular Bioeconomy.Different screening approaches have been used to discover enzymes that are active at extremes of temperature (up 120 °C), pH (0.1 to 11), high salt concentration (up to 30%) as well as activity in the presence of solvents (up to 99%). The majority of published enzymes were revealed from bacterial or archaeal isolates by traditional activity-based screening techniques. However, the latest developments in molecular biology, bioinformatics, and genomics have revolutionized life science technologies. Post-genomic era has contributed to the discovery of millions of sequences coding for a huge number of biocatalysts. Both strategies, activity- and sequence-based screening approaches, are complementary and contribute to the discovery of unique enzymes that have not been extensively utilized so far.
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Affiliation(s)
- Christin Burkhardt
- Institute of Technical Biocatalysis, Center for Biobased Solutions, Hamburg University of Technology, Am Schwarzenberg-Campus 4, 21073, Hamburg, Germany
| | - Leon Baruth
- Institute of Technical Biocatalysis, Center for Biobased Solutions, Hamburg University of Technology, Am Schwarzenberg-Campus 4, 21073, Hamburg, Germany
| | - Neele Meyer-Heydecke
- Institute of Technical Biocatalysis, Center for Biobased Solutions, Hamburg University of Technology, Am Schwarzenberg-Campus 4, 21073, Hamburg, Germany
| | - Barbara Klippel
- Institute of Technical Biocatalysis, Center for Biobased Solutions, Hamburg University of Technology, Am Schwarzenberg-Campus 4, 21073, Hamburg, Germany
| | - Armine Margaryan
- Department of Biochemistry, Microbiology and Biotechnology, Yerevan State University, Alex Manoogian 1, 0025, Yerevan, Armenia
- Research Institute of Biology, Yerevan State University, Alex Manoogian 1, 0025, Yerevan, Armenia
| | - Ani Paloyan
- Scientific and Production Center, "Armbiotechnology" NAS RA, 14 Gyurjyan Str. 0056, Yerevan, Armenia
| | - Hovik H Panosyan
- Department of Biochemistry, Microbiology and Biotechnology, Yerevan State University, Alex Manoogian 1, 0025, Yerevan, Armenia
- Research Institute of Biology, Yerevan State University, Alex Manoogian 1, 0025, Yerevan, Armenia
| | - Garabed Antranikian
- Institute of Technical Biocatalysis, Center for Biobased Solutions, Hamburg University of Technology, Am Schwarzenberg-Campus 4, 21073, Hamburg, Germany.
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11
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Di Rocco G, Taunt HN, Berto M, Jackson HO, Piccinini D, Carletti A, Scurani G, Braidi N, Purton S. A PETase enzyme synthesised in the chloroplast of the microalga Chlamydomonas reinhardtii is active against post-consumer plastics. Sci Rep 2023; 13:10028. [PMID: 37340047 DOI: 10.1038/s41598-023-37227-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2023] [Accepted: 06/18/2023] [Indexed: 06/22/2023] Open
Abstract
Polyethylene terephthalate hydrolases (PETases) are a newly discovered and industrially important class of enzymes that catalyze the enzymatic degradation of polyethylene terephatalate (PET), one of the most abundant plastics in the world. The greater enzymatic efficiencies of PETases compared to close relatives from the cutinase and lipase families have resulted in increasing research interest. Despite this, further characterization of PETases is essential, particularly regarding their possible activity against other kinds of plastic. In this study, we exploited for the first time the use of the microalgal chloroplast for more sustainable synthesis of a PETase enzyme. A photosynthetic-restoration strategy was used to generate a marker-free transformant line of the green microalga Chlamydomonas reinhardtii in which the PETase from Ideonella sakaiensis was constitutively expressed in the chloroplast. Subsequently, the activity of the PETase against both PET and post-consumer plastics was investigated via atomic force microscopy, revealing evidence of degradation of the plastics.
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Affiliation(s)
- Giulia Di Rocco
- Department of Life Sciences, University of Modena and Reggio Emilia, 41125, Modena, Italy.
| | - Henry N Taunt
- Algal Research Group, Department of Structural and Molecular Biology, University College London, Gower Street, London, UK
| | - Marcello Berto
- Department of Life Sciences, University of Modena and Reggio Emilia, 41125, Modena, Italy
| | - Harry O Jackson
- Algal Research Group, Department of Structural and Molecular Biology, University College London, Gower Street, London, UK
| | - Daniele Piccinini
- Department of Life Sciences, University of Modena and Reggio Emilia, 41125, Modena, Italy
| | - Alan Carletti
- Department of Life Sciences, University of Modena and Reggio Emilia, 41125, Modena, Italy
| | - Giulia Scurani
- Department of Chemical and Geological Sciences, University of Modena and Reggio Emilia, 41125, Modena, Italy
| | - Niccolò Braidi
- Department of Chemical and Geological Sciences, University of Modena and Reggio Emilia, 41125, Modena, Italy
| | - Saul Purton
- Algal Research Group, Department of Structural and Molecular Biology, University College London, Gower Street, London, UK
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12
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Jayasekara SK, Joni HD, Jayantha B, Dissanayake L, Mandrell C, Sinharage MM, Molitor R, Jayasekara T, Sivakumar P, Jayakody LN. Trends in in-silico guided engineering of efficient polyethylene terephthalate (PET) hydrolyzing enzymes to enable bio-recycling and upcycling of PET. Comput Struct Biotechnol J 2023; 21:3513-3521. [PMID: 37484494 PMCID: PMC10362282 DOI: 10.1016/j.csbj.2023.06.004] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2023] [Revised: 06/01/2023] [Accepted: 06/03/2023] [Indexed: 07/25/2023] Open
Abstract
Polyethylene terephthalate (PET) is the largest produced polyester globally, and less than 30% of all the PET produced globally (∼6 billion pounds annually) is currently recycled into lower-quality products. The major drawbacks in current recycling methods (mechanical and chemical), have inspired the exploration of potentially efficient and sustainable PET depolymerization using biological approaches. Researchers have discovered efficient PET hydrolyzing enzymes in the plastisphere and have demonstrated the selective degradation of PET to original monomers thus enabling biological recycling or upcycling. However, several significant hurdles such as the less efficiency of the hydrolytic reaction, low thermostability of the enzymes, and the inability of the enzyme to depolymerize crystalline PET must be addressed in order to establish techno-economically feasible commercial-scale biological PET recycling or upcycling processes. Researchers leverage a synthetic biology-based design; build, test, and learn (DBTL) methodology to develop commercially applicable efficient PET hydrolyzing enzymes through 1) high-throughput metagenomic and proteomic approaches to discover new PET hydrolyzing enzymes with superior properties: and, 2) enzyme engineering approaches to modify and optimize PET hydrolyzing properties. Recently, in-silico platforms including molecular mechanics and machine learning concepts are emerging as innovative tools for the development of more efficient and effective PET recycling through the exploration of novel mutations in PET hydrolyzing enzymes. In-silico-guided PET hydrolyzing enzyme engineering with DBTL cycles enables the rapid development of efficient variants of enzymes over tedious conventional enzyme engineering methods such as random or directed evolution. This review highlights the potential of in-silico-guided PET degrading enzyme engineering to create more efficient variants, including Ideonella sakaiensis PETase (IsPETase) and leaf-branch compost cutinases (LCC). Furthermore, future research prospects are discussed to enable a sustainable circular economy through the bioconversion of PET to original or high-value platform chemicals.
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Affiliation(s)
- Sandhya K. Jayasekara
- School of Biological Science, Southern Illinois University Carbondale, Carbondale, IL, USA
| | - Hriday Dhar Joni
- School of Physics and Applied Physics, Southern Illinois University Carbondale, Carbondale, IL, USA
| | - Bhagya Jayantha
- School of Biological Science, Southern Illinois University Carbondale, Carbondale, IL, USA
| | - Lakshika Dissanayake
- School of Biological Science, Southern Illinois University Carbondale, Carbondale, IL, USA
| | - Christopher Mandrell
- School of Physics and Applied Physics, Southern Illinois University Carbondale, Carbondale, IL, USA
| | - Manuka M.S. Sinharage
- School of Physics and Applied Physics, Southern Illinois University Carbondale, Carbondale, IL, USA
| | - Ryan Molitor
- School of Physics and Applied Physics, Southern Illinois University Carbondale, Carbondale, IL, USA
| | - Thushari Jayasekara
- School of Physics and Applied Physics, Southern Illinois University Carbondale, Carbondale, IL, USA
| | - Poopalasingam Sivakumar
- School of Physics and Applied Physics, Southern Illinois University Carbondale, Carbondale, IL, USA
| | - Lahiru N. Jayakody
- School of Biological Science, Southern Illinois University Carbondale, Carbondale, IL, USA
- Fermentation Science Institute, Southern Illinois University Carbondale, Carbondale, IL, USA
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13
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Orlando M, Molla G, Castellani P, Pirillo V, Torretta V, Ferronato N. Microbial Enzyme Biotechnology to Reach Plastic Waste Circularity: Current Status, Problems and Perspectives. Int J Mol Sci 2023; 24:3877. [PMID: 36835289 PMCID: PMC9967032 DOI: 10.3390/ijms24043877] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2023] [Revised: 02/08/2023] [Accepted: 02/10/2023] [Indexed: 02/17/2023] Open
Abstract
The accumulation of synthetic plastic waste in the environment has become a global concern. Microbial enzymes (purified or as whole-cell biocatalysts) represent emerging biotechnological tools for waste circularity; they can depolymerize materials into reusable building blocks, but their contribution must be considered within the context of present waste management practices. This review reports on the prospective of biotechnological tools for plastic bio-recycling within the framework of plastic waste management in Europe. Available biotechnology tools can support polyethylene terephthalate (PET) recycling. However, PET represents only ≈7% of unrecycled plastic waste. Polyurethanes, the principal unrecycled waste fraction, together with other thermosets and more recalcitrant thermoplastics (e.g., polyolefins) are the next plausible target for enzyme-based depolymerization, even if this process is currently effective only on ideal polyester-based polymers. To extend the contribution of biotechnology to plastic circularity, optimization of collection and sorting systems should be considered to feed chemoenzymatic technologies for the treatment of more recalcitrant and mixed polymers. In addition, new bio-based technologies with a lower environmental impact in comparison with the present approaches should be developed to depolymerize (available or new) plastic materials, that should be designed for the required durability and for being susceptible to the action of enzymes.
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Affiliation(s)
- Marco Orlando
- Department of Biotechnology and Life Sciences, University of Insubria, Via Dunant, 21100 Varese, Italy
| | - Gianluca Molla
- Department of Biotechnology and Life Sciences, University of Insubria, Via Dunant, 21100 Varese, Italy
| | - Pietro Castellani
- Department of Theoretical and Applied Sciences (DiSTA), University of Insubria, Via G.B. Vico 46, 21100 Varese, Italy
| | - Valentina Pirillo
- Department of Biotechnology and Life Sciences, University of Insubria, Via Dunant, 21100 Varese, Italy
| | - Vincenzo Torretta
- Department of Theoretical and Applied Sciences (DiSTA), University of Insubria, Via G.B. Vico 46, 21100 Varese, Italy
| | - Navarro Ferronato
- Department of Theoretical and Applied Sciences (DiSTA), University of Insubria, Via G.B. Vico 46, 21100 Varese, Italy
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14
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An Ultra-Sensitive Comamonas thiooxidans Biosensor for the Rapid Detection of Enzymatic Polyethylene Terephthalate (PET) Degradation. Appl Environ Microbiol 2023; 89:e0160322. [PMID: 36507653 PMCID: PMC9888244 DOI: 10.1128/aem.01603-22] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Polyethylene terephthalate (PET) is a prevalent synthetic polymer that is known to contaminate marine and terrestrial environments. Currently, only a limited number of PET-active microorganisms and enzymes (PETases) are known. This is in part linked to the lack of highly sensitive function-based screening assays for PET-active enzymes. Here, we report on the construction of a fluorescent biosensor based on Comamonas thiooxidans strain S23. C. thiooxidans S23 transports and metabolizes TPA, one of the main breakdown products of PET, using a specific tripartite tricarboxylate transporter (TTT) and various mono- and dioxygenases encoded in its genome in a conserved operon ranging from tphC-tphA1. TphR, an IclR-type transcriptional regulator is found upstream of the tphC-tphA1 cluster where TPA induces transcription of tphC-tphA1 up to 88-fold in exponentially growing cells. In the present study, we show that the C. thiooxidans S23 wild-type strain, carrying the sfGFP gene fused to the tphC promoter, senses TPA at concentrations as low as 10 μM. Moreover, a deletion mutant lacking the catabolic genes involved in TPA degradation thphA2-A1 (ΔtphA2A3BA1) is up to 10,000-fold more sensitive and detects TPA concentrations in the nanomolar range. This is, to our knowledge, the most sensitive reporter strain for TPA and we demonstrate that it can be used for the detection of enzymatic PET breakdown products. IMPORTANCE Plastics and microplastics accumulate in all ecological niches. The construction of more sensitive biosensors allows to monitor and screen potential PET degradation in natural environments and industrial samples. These strains will also be a valuable tool for functional screenings of novel PETase candidates and variants or monitoring of PET recycling processes using biocatalysts. Thereby they help us to enrich the known biodiversity and efficiency of PET degrading organisms and enzymes and understand their contribution to environmental plastic degradation.
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15
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Pirillo V, Orlando M, Battaglia C, Pollegioni L, Molla G. Efficient polyethylene terephthalate degradation at moderate temperature: a protein engineering study of LC-cutinase highlights the key role of residue 243. FEBS J 2023. [PMID: 36695006 DOI: 10.1111/febs.16736] [Citation(s) in RCA: 13] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2022] [Revised: 12/31/2022] [Accepted: 01/23/2023] [Indexed: 01/26/2023]
Abstract
Enzymatic degradation of poly(ethylene terephthalate) (PET) is becoming a reality because of the identification of novel PET-hydrolysing enzymes (PHEs) and the engineering of evolved enzyme variants. Here, improved variants of leaf-branch compost cutinase (LCC), a thermostable enzyme isolated by a metagenomic approach, were generated by a semi-rational protein engineering approach. Starting from a deleted LCC form lacking the secretion signal (ΔLCC), single and double variants possessing a higher activity on PET were isolated. The single-point F243T ΔLCC variant partially (~ 67%) depolymerized amorphous PET film producing ~ 21.9 mm of products after 27 h of reaction at 72 °C. The S101N/F243T ΔLCC double variant reached a further increase in activity on PET. Notably, for both single and double variants the highest conversion yield was obtained at 55 °C. Kinetics studies and molecular dynamics simulations support that a slight decreased affinity for PET is responsible for the superior degradation performance of the S101N/F243T variant and that this stems from a slightly higher flexibility of the active site region close to position 243. Furthermore, our findings question the need for a high reaction temperature for PET degradation, at least for LCC: at ≥ 70 °C, the conversion of amorphous PET into a more crystalline polymer, resistant to enzymatic hydrolysis, is favoured. The evolved S101N/F243T ΔLCC variant is able to depolymerize fully 1.3 g of untreated postconsumer PET waste in ≤ 3 days at 55 °C (using 1.25 mg of enzyme only), this making PET enzymatic degradation by engineering LCC a more ecofriendly and sustainable process.
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Affiliation(s)
- Valentina Pirillo
- "The Protein Factory 2.0", Department of Biotechnology and Life Sciences (DBSV), University of Insubria, Varese, Italy
| | - Marco Orlando
- "The Protein Factory 2.0", Department of Biotechnology and Life Sciences (DBSV), University of Insubria, Varese, Italy
| | - Caren Battaglia
- "The Protein Factory 2.0", Department of Biotechnology and Life Sciences (DBSV), University of Insubria, Varese, Italy
| | - Loredano Pollegioni
- "The Protein Factory 2.0", Department of Biotechnology and Life Sciences (DBSV), University of Insubria, Varese, Italy
| | - Gianluca Molla
- "The Protein Factory 2.0", Department of Biotechnology and Life Sciences (DBSV), University of Insubria, Varese, Italy
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16
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Holst LH, Madsen NG, Toftgård FT, Rønne F, Moise IM, Petersen EI, Fojan P. De novo design of a polycarbonate hydrolase. Protein Eng Des Sel 2023; 36:gzad022. [PMID: 38035789 DOI: 10.1093/protein/gzad022] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2023] [Revised: 10/31/2023] [Accepted: 11/14/2023] [Indexed: 12/02/2023] Open
Abstract
Enzymatic degradation of plastics is currently limited to the use of engineered natural enzymes. As of yet, all engineering approaches applied to plastic degrading enzymes retain the natural $\alpha /\beta $-fold. While mutations can be used to increase thermostability, an inherent maximum likely exists for the $\alpha /\beta $-fold. It is thus of interest to introduce catalytic activity toward plastics in a different protein fold to escape the sequence space of plastic degrading enzymes. Here, a method for designing highly thermostable enzymes that can degrade plastics is described. With the help of Rosetta an active site catalysing the hydrolysis of polycarbonate is introduced into a set of thermostable scaffolds. Through computational evaluation, a potential PCase was selected and produced recombinantly in Escherichia coli. Thermal analysis suggests that the design has a melting temperature of >95$^{\circ }$C. Activity toward polycarbonate was confirmed using atomic force spectroscopy (AFM), proving the successful design of a PCase.
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Affiliation(s)
- Laura H Holst
- Material Science and Engineering Group, Department of Materials and Production, Aalborg University, 9000 Aalborg, Denmark
| | - Niklas G Madsen
- Material Science and Engineering Group, Department of Materials and Production, Aalborg University, 9000 Aalborg, Denmark
| | - Freja T Toftgård
- Material Science and Engineering Group, Department of Materials and Production, Aalborg University, 9000 Aalborg, Denmark
| | - Freja Rønne
- Material Science and Engineering Group, Department of Materials and Production, Aalborg University, 9000 Aalborg, Denmark
| | - Ioana-Malina Moise
- Material Science and Engineering Group, Department of Materials and Production, Aalborg University, 9000 Aalborg, Denmark
| | - Evamaria I Petersen
- Material Science and Engineering Group, Department of Materials and Production, Aalborg University, 9000 Aalborg, Denmark
| | - Peter Fojan
- Material Science and Engineering Group, Department of Materials and Production, Aalborg University, 9000 Aalborg, Denmark
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17
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Charupanit K, Tipmanee V, Sutthibutpong T, Limsakul P. In Silico Identification of Potential Sites for a Plastic-Degrading Enzyme by a Reverse Screening through the Protein Sequence Space and Molecular Dynamics Simulations. MOLECULES (BASEL, SWITZERLAND) 2022; 27:molecules27103353. [PMID: 35630830 PMCID: PMC9143596 DOI: 10.3390/molecules27103353] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/29/2022] [Revised: 05/19/2022] [Accepted: 05/20/2022] [Indexed: 11/16/2022]
Abstract
The accumulation of polyethylene terephthalate (PET) seriously harms the environment because of its high resistance to degradation. The recent discovery of the bacteria-secreted biodegradation enzyme, PETase, sheds light on PET recycling; however, the degradation efficiency is far from practical use. Here, in silico alanine scanning mutagenesis (ASM) and site-saturation mutagenesis (SSM) were employed to construct the protein sequence space from binding energy of the PETase–PET interaction to identify the number and position of mutation sites and their appropriate side-chain properties that could improve the PETase–PET interaction. The binding mechanisms of the potential PETase variant were investigated through atomistic molecular dynamics simulations. The results show that up to two mutation sites of PETase are preferable for use in protein engineering to enhance the PETase activity, and the proper side chain property depends on the mutation sites. The predicted variants agree well with prior experimental studies. Particularly, the PETase variants with S238C or Q119F could be a potential candidate for improving PETase. Our combination of in silico ASM and SSM could serve as an alternative protocol for protein engineering because of its simplicity and reliability. In addition, our findings could lead to PETase improvement, offering an important contribution towards a sustainable future.
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Affiliation(s)
- Krit Charupanit
- Department of Biomedical Sciences and Biomedical Engineering, Faculty of Medicine, Prince of Songkla University, Songkhla 90110, Thailand; (K.C.); (V.T.)
| | - Varomyalin Tipmanee
- Department of Biomedical Sciences and Biomedical Engineering, Faculty of Medicine, Prince of Songkla University, Songkhla 90110, Thailand; (K.C.); (V.T.)
| | - Thana Sutthibutpong
- Theoretical and Computational Physics Group, Department of Physics, Faculty of Science, King Mongkut’s University of Technology Thonburi (KMUTT), Bangkok 10140, Thailand;
- Center of Excellence in Theoretical and Computational Science (TaCS-CoE), Faculty of Science, King Mongkut’s University of Technology Thonburi (KMUTT), Bangkok 10140, Thailand
| | - Praopim Limsakul
- Division of Physical Science, Faculty of Science, Prince of Songkla University, Songkhla 90110, Thailand
- Center of Excellence for Trace Analysis and Biosensor (TAB-CoE), Faculty of Science, Prince of Songkla University, Songkhla 90110, Thailand
- Correspondence:
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