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A third type of PETase from the marine Halopseudomonas lineage
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Researchers identified a previously unknown class of PET-degrading enzyme (PETase) from marine Halopseudomonas bacteria, expanding the known diversity of plastic-degrading enzymes in ocean environments. This discovery adds to the growing catalog of marine microorganisms capable of breaking down polyethylene terephthalate, a widely used plastic.
The enzymatic degradation of polyethylene terephthalate (PET) offers a sustainable solution for PET recycling. Over the past two decades, more than 100 PETases have been characterized, primarily exhibiting similar sequences and structures. Here, we report PET-degrading α/β hydrolases, including HaloPETase1 from the marine Halopseudomonas lineage, thereby extending the narrow sequence space by novel features at the active site. The crystal structure of HaloPETase1 was determined to a resolution of 1.16 Å, revealing a unique active site architecture and a lack of the canonical π-stacking clamp found in PETases so far. Further, variations in active site composition and loop structures were observed. Additionally, we found five more enzymes from the same lineage, two of which have a high similarity to type IIa bacterial PETases, while the other three resemble HaloPETase1. All these enzymes exhibited high salt tolerance ranging from 2.5 to 5 M NaCl, leading to higher total product releases upon PET degradation at 40 or 50°C. Based on these findings, we propose an extension of the existing PETase classification system to include type III PETases.
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A Novel Polyester Hydrolase From the Marine Bacterium Pseudomonas aestusnigri – Structural and Functional Insights
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Widespread distribution of bacteria containing PETases with a functional motif across global oceans
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Using bioinformatics and AI-based protein structure prediction, researchers developed an algorithm to distinguish functional PET-degrading enzymes (PETases) from non-functional variants, identifying a high-confidence sequence motif for active PETases. Metagenomic analysis of 415 ocean samples revealed 23 PETase variants in nearly 80% of samples, predominantly between 1,000–2,000 meters depth and at the surface in high-pollution regions, with ocean PETases mainly encoded by Pseudomonadales bacteria.
In silico structural analysis and biochemical characterization of a novel PETase from Antarctic Streptomyces sp .
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Researchers characterized a novel PET-degrading enzyme (SsPETase) from Antarctic Streptomyces bacteria, using AlphaFold structural prediction and molecular dynamics simulations to reveal key catalytic residues and a substrate-dependent conformational shift that activates the enzyme, providing a foundation for engineering more efficient plastic-degrading enzymes.
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When a large batch of papers lands in the Atlas, we read through it and send a short write-up of what stood out.