In a groundbreaking stride toward sustainable chemical production, scientists have unveiled remarkable insights into a bacterial enzyme capable of synthesizing ethylene, a fundamental building block in plastic manufacturing traditionally derived from fossil fuels. Ethylene’s ubiquity in the production of myriad plastics makes finding greener pathways to its manufacture a pivotal quest in reducing the environmental toll of petrochemical dependence. Researchers from The Ohio State University, UCLA, and national laboratories including the Department of Energy’s Joint Genome Institute and Brookhaven National Lab have collaboratively decoded the architecture and catalytic mechanisms of methylthio-alkane reductase (MAR), a bacterial enzyme previously shrouded in mystery.
At the crux of this investigation lies the enzyme MAR, which certain bacteria use to convert organic sulfur compounds into ethylene. For the first time, scientists have successfully extracted MAR in its pure enzymatic form, an unprecedented accomplishment that has opened the door to an enhanced understanding of its function and structure. This feat, led by Justin North and his team at Ohio State along with their colleagues at UCLA and DOE laboratories, sets the stage for bioengineered applications wherein such enzymes could replace fossil-fuel-based ethylene synthesis methods.
The investigative journey began with genetic explorations that revealed curious homology between the genes encoding MAR and those responsible for nitrogenase enzymes, which fix atmospheric nitrogen into biologically usable forms. This unexpected link suggested a deep evolutionary connection and hinted at the presence of complex metal cofactors integral to the enzyme’s catalytic activity. Nitrogenases, characterized by intricate iron-sulfur clusters, have long been regarded as among the most sophisticated metalloenzymes known in nature.
Capitalizing on advanced synthetic biology, researchers employed gene synthesis technologies to produce multiple MAR genetic variants, subsequently expressing these genes within the soil bacterium Rhodospirillum rubrum. This enabled the production and isolation of MAR protein in quantities sufficient for detailed study. Srividya Murali’s pioneering efforts in protein isolation were instrumental in overcoming prior technical barriers, rendering the enzyme amenable to biophysical and structural elucidation.
Spectroscopic analyses, spearheaded by Hannah Shafaat’s group at UCLA, illuminated the intricate electron transfer processes governing MAR’s catalytic conversion of sulfur compounds into ethylene. These measurements revealed that MAR’s metal cofactors engage in complex redox activities, reflecting both parallels and distinctions from nitrogenase. The electron flow pathways sculpted within MAR’s massive protein complex underscore its finely tuned catalytic prowess, manifested in selective sulfur extraction and ethylene generation.
Structural revelations afforded by cryogenic electron microscopy at Brookhaven National Laboratory further demystified MAR’s molecular composition. Researchers unveiled that MAR shares notable architectural motifs with nitrogenase, though its metal center exhibits distinctive variations tailored to its unique chemical function. These metal cofactors comprise clusters of iron and sulfur atoms assembled in configurations that enable remarkable catalytic versatility. Such structural nuances explain MAR’s predilection for sulfur extraction compared to nitrogenase’s nitrogen-fixing role.
The elucidation of MAR’s structure-function relationship fosters a nuanced understanding of how evolutionary cousins among enzymes adapt metal centers to perform distinct catalytic tasks. This insight not only enriches the fundamental biochemistry of metalloenzymes but also provides a tangible framework for future enzyme engineering endeavors. The ultimate ambition is to optimize MAR variants with superior ethylene production efficiency under industrially relevant conditions, thereby enabling a transition to bio-based ethylene synthesis.
Transitioning from fundamental science to applied biotechnology, the researchers aspire to harness MAR as a biocatalyst that can supplant traditional ethylene production processes. Achieving this requires strategic protein engineering to enhance turnover rates, stability, and substrate specificity, thus ensuring that microbial ethylene generation is both economically and environmentally competitive. This pursuit aligns with broader objectives of reducing greenhouse gas emissions and reliance on non-renewable resources in chemical manufacturing.
Collaboration among interdisciplinary teams—integrating microbiology, biochemistry, synthetic biology, spectroscopy, and structural biology—has been pivotal in this scientific advance. The fusion of expertise from Ohio State University, UCLA, and DOE facilities exemplifies how cooperative research accelerates breakthroughs that hold promise for sustainable industrial innovations. Such partnerships also highlight the pivotal role of cutting-edge instrumentation and methodologies, from genetic engineering platforms to high-resolution cryo-EM.
The research makes significant headway by not only uncovering the evolutionary lineage of MAR but also elucidating how its metal cofactors orchestrate electron movement during catalysis. Understanding these molecular intricacies affords strategic entry points for modifying the enzyme’s active sites or electron pathways to boost efficiency. This work thereby paves a path for rational design approaches aimed at tailoring enzymes for bespoke chemical transformations.
As environmental imperatives intensify the need for alternative materials chemistry, this pioneering study marks an important milestone in the convergence of microbiology and green chemistry. It lays the foundation for a future where bioengineered microbes equipped with optimized MAR enzymes could serve as renewable ethylene factories, reducing plastic production’s carbon footprint. The promise of a fossil fuel–independent ethylene synthesis system is tantalizingly close, enabled by a profound comprehension of bacterial enzyme sophistication.
This study was financed by the Department of Energy’s Office of Science under its Physical Biosciences program, reflecting governmental commitment to fostering scientific research addressing sustainability challenges. The multi-institutional collaboration, technical innovations, and fundamental discoveries position this research on the cutting edge, offering both immediate scientific impact and long-term industrial relevance.
In summary, the identification, isolation, and comprehensive characterization of methylthio-alkane reductase have illuminated a biochemical pathway for sustainable ethylene synthesis via bacterial metabolism. At the intersection of microbiology, enzymology, and materials science, this achievement signals a paradigm shift in how we might reimagine plastic production—transforming an ancient bacterial enzyme into a cornerstone of the circular bioeconomy.
Subject of Research: Not applicable
Article Title: Architecture, catalysis and regulation of methylthio-alkane reductase for bacterial sulfur acquisition from volatile organic compounds
News Publication Date: 23-Oct-2025
Web References:
Nature Catalysis Article
North Lab at Ohio State
Shafaat Lab at UCLA
DOE Joint Genome Institute
Brookhaven National Lab Cryo-EM
References:
North, J., et al. (2025). Architecture, catalysis and regulation of methylthio-alkane reductase for bacterial sulfur acquisition from volatile organic compounds. Nature Catalysis. DOI: 10.1038/s41929-025-01425-3
North, J., et al. (2020). A new method for making a key component of plastics. Science. DOI: 10.1126/science.abb6310
Image Credits: Not provided
Keywords
Methylthio-alkane reductase, ethylene biosynthesis, bacterial enzymes, nitrogenase analogs, metalloenzyme structure, iron-sulfur clusters, cryogenic electron microscopy, enzyme engineering, sustainable plastics, bio-based ethylene, enzymatic catalysis, microbial biotechnology
Tags: advancements in biotechnologybacterial enzyme for ethylene synthesisbioengineering for sustainable plasticscollaborative scientific breakthroughsenvironmental impact of plastic manufacturingenzymes in chemical productiongreen chemistry innovationsmethylthio-alkane reductase researchOhio State University researchreducing petrochemical dependencesustainable chemical synthesis methodssustainable ethylene production
