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Temperature-Dependent Active-Site Rearrangements of PETaseSM14: Insights from Molecular Dynamics Simulations
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Researchers used molecular dynamics simulations at multiple temperatures to investigate how PETaseSM14 — a marine-derived PET-degrading enzyme — changes conformation at its active site, finding that moderate warming exposes the catalytic residue to enable substrate binding while excessive heat disrupts the catalytic triad, providing targets for enzyme engineering.
Polyethylene terephthalate (PET) is a synthetic polymer that is widely used in the production of textiles, packaging materials, and beverage bottles. However, its high durability and resistance to abiotic degradation result in serious environmental and health problems. PETase is an enzyme that can depolymerize PET into value-added products, thereby providing an environmentally friendly strategy for PET recycling. PETaseSM14 from a marine sponge, Streptomyces sp. SM14, has a high salt tolerance and thermal stability, thus suggesting its potential for PET degradation applications. However, the substrate recognition mechanism of PETase remains unclear because the catalytic residue is buried within residues that form the substrate-binding cleft. To elucidate the molecular mechanism of PETaseSM14, all-atom molecular dynamics simulations were performed at 300, 320, and 340 K. The results revealed that the overall α/β fold remained stable at all temperatures, whereas temperature-dependent local fluctuations and conformational changes were observed in the substrate-binding cleft and N-terminal region. At 300 and 320 K, positional shifts and conformational changes in Tyr88 exposed the catalytic Ser156 to the solvent, thereby forming a potential substrate-binding cleft. In contrast, at 340 K, which is higher than the melting temperature of PETaseSM14, disruption of the charge-relay system of the catalytic triad occurs through conformational changes in His234. Substantial temperature-dependent conformational and positional changes in the N-terminal region of PETaseSM14 were observed at 320 and 340 K. These results provide mechanistic insight into the temperature-dependent active-site rearrangements and offer rational engineering strategies to enhance the efficiency of PETase for PET biodegradation.
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Researchers used molecular simulations to understand why the plastic-degrading enzyme FAST-PETase works better at 50°C than at lower temperatures when breaking down PET plastic. They found that at the optimal temperature the enzyme's active site pre-organizes itself to bind PET more efficiently, and the enzyme forces the plastic into a more reactive shape. Understanding these mechanisms can guide the engineering of even more effective enzymes for breaking down PET microplastics and plastic waste at practical scales.
Molecular Insights into the Enhanced Activity and/or Thermostability of PET Hydrolase by D186 Mutations
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This study used molecular simulations to analyze how D186 mutations in PETase affect its activity and thermostability, revealing that non-active-site residues in the enzyme's second shell play an important role in PET plastic degradation efficiency.
Temperature-Dependent Reorganization of Conformational Dynamics and Interaction Networks Underlies Thermostability in PET-Degrading Enzymes
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Scientists are studying how to engineer sturdier enzymes that can break down plastic bottles (PET) into reusable materials, since natural plastic-eating enzymes tend to fall apart at the high temperatures needed for efficient recycling. By using computer simulations to compare a natural enzyme with two engineered, heat-resistant versions, researchers pinpointed exactly what structural features let the improved enzymes stay stable and functional under heat. This matters because better plastic-recycling enzymes could help reduce the massive amount of plastic waste that breaks down into microplastics — tiny particles increasingly found in our food
Molecular dynamics simulations of temperature-dependent PET binding in PETase, ThermoPETase, and FAST-PETase
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Molecular dynamics simulations comparing wild-type IsPETase with two engineered variants (ThermoPETase and FAST-PETase) showed that FAST-PETase exhibited the highest thermal stability and preserved PET binding at elevated temperatures where the wild-type enzyme lost substrate contact. Engineering thermostable PET-degrading enzymes is a promising strategy for biological treatment of PET microplastic pollution at industrial scales.
Atomistic-Level Insights into the Role of Mutations in the Engineering of PET Hydrolases: A Systematic Review
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This systematic review examined the role of mutations in engineering PET-degrading enzymes including TfCut2, IsPETase, and LCC across 20 studies, integrating molecular dynamics simulations with experimental findings. The review identifies key residue hotspots enhancing catalytic performance and thermostability, demonstrating MD simulations as powerful tools guiding targeted mutation strategies for enzymatic plastic degradation.
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