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

Despite extensive research on a multitude of crystalline materials, most Weyl materials hitherto discovered have been overwhelmed by the influence of trivial electrons that obscure the presence of Weyl fermions. The successful synthesis of a material that supports a single pair of Weyl fermions without the interference of irrelevant electronic states represents not only a significant scientific breakthrough but also a culmination of years of theoretical predictions and experimental endeavors.

The research, published in the esteemed journal Nature, is the result of a four-year collaborative effort involving CEMS, the RIKEN Interdisciplinary Theoretical and Mathematical Sciences Program (iTHEMS), the Quantum-Phase Electronics Center (QPEC) at the University of Tokyo, the Institute for Materials Research at Tohoku University, and Nanyang Technological University in Singapore. The team ingeniously transformed a topological semiconductor into a Weyl semimetal, revisiting a strategy that had been theorized in 2011 but subsequently fell into relative obscurity within the scientific community.

Topological semiconductors, characterized by a small energy gap, can transition between insulating and conducting states. On the other hand, semimetals exist at the very brink of this transition, possessing a unique zero energy gap. This characteristic is exceedingly rare in natural materials, with graphene often cited as a prime example of a material featuring similar properties, particularly regarding its applications in flexible electronics and moiré physics.

The core material used in this groundbreaking study is bismuth telluride (Bi₂Te₃), a well-known topological semiconductor. Researchers carefully manipulated the chemical composition of the material by substituting chromium for bismuth, creating a compound denoted as (Cr,Bi)₂Te₃. This meticulous adjustment of the material’s properties allowed the team to unravel new physics beyond previously established topological semiconductor behavior, as evidenced by the observation of a large anomalous Hall effect (AHE).

The AHE observed in (Cr,Bi)₂Te₃ is particularly noteworthy, as it enables researchers to delve deeper into the material’s electronic structure. This uniquely simple electronic configuration has empowered the research team to quantitatively correlate their experimental results with theoretical predictions, thereby establishing a clear link between the large AHE and the emergent Weyl fermions. This connection signifies a pivotal moment in understanding quantum materials and their potential applications.

Leading author Ilya Belopolski expressed surprise at the discovery, noting that different research communities had already developed the necessary theoretical and experimental knowledge to synthesize this Weyl semimetal but had not effectively communicated. The success of this research illustrates the importance of collaboration across disciplines and highlights how missed opportunities can arise in the absence of dialogue between different scientific fields.

Belopolski attributed the emergence of this critical insight to the unique atmosphere fostered at RIKEN, where brilliant researchers come together in a creatively stimulating environment. The collaboration between talented research groups from various countries exemplifies the global pursuit of scientific knowledge and underlines how a collaborative approach can lead to significant breakthroughs that might otherwise remain unrealized.

One of the most exciting potential applications of this newly discovered Weyl semimetal lies in terahertz (THz) technology. Classical semiconductors are generally unable to absorb photons below certain energy thresholds dictated by their energy gaps. However, semimetals, with their zero energy gap, can effectively absorb light across the THz frequency range. This unique property positions Weyl semimetals as promising candidates for creating and detecting THz light, opening doors to potential advancements in communication technologies and sensor applications.

The implications of this discovery extend beyond just terahertz applications, as the research team anticipates exploration into high-performance sensors, low-power electronics, and innovative optoelectronic devices. The enthusiasm surrounding the prospects of this new quantum phase of matter embodies the dynamic research atmosphere at CEMS, where emerging technologies continuously push the boundaries of material science.

Lixuan Tai, a postdoctoral researcher who joined the Strong Correlation Quantum Transport Laboratory close to the publication of the findings, expressed exhilaration regarding the opportunities that this new Weyl semimetal presents for ongoing and future research. The team is poised to leverage the characteristics of this material to further explore its unique phases and properties, potentially sparking a wave of discoveries in quantum materials.

As researchers continue to delve into the properties of the ideal Weyl semimetal, they anticipate a rich landscape of inquiry that will lead to new methodologies and technological innovations. The intersection of theory and experimentation in this context illustrates the remarkable progress being made in the understanding of quantum materials, a field that will undoubtedly yield significant advancements in science and technology for years to come.

The synthesis of the ideal Weyl semimetal thus represents a transformative achievement in the realm of quantum transport and materials science. It paves the way for further exploration and understanding of Weyl fermions and their associated electromagnetic properties, signifying a potential turning point in how researchers approach the study of quantum materials and highlights the value of collaboration in unlocking the mysteries of the universe.

As the research community continues to build upon this foundation, the exciting prospects for the development of new devices, sensors, and methodologies driven by the unique properties of this Weyl semimetal will likely be a central theme in future scientific discourse. This breakthrough not only illustrates the potential of quantum materials but also serves as an exemplar of what can be achieved through sustained collaboration and innovative thinking in scientific research.

Subject of Research: Quantum Materials
Article Title: Synthesis of a semimetallic Weyl ferromagnet with point Fermi surface
News Publication Date: 22-Jan-2025
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