VAAM Research Award
Johannes Rebelein, Marburg receives the VAAM Research Award 2024
Dr. Johannes Rebelein from the Max Planck Institute in Marburg characterized a bacterial enzyme that can convert carbon monoxide (CO) and carbon dioxide (CO2) into hydrocarbons. This unique natural biocatalyst could make the greenhouse gas CO2 usable for the production of sustainable chemicals, fuels or plastics. For this discovery, Rebelein has been awarded the 2024 Research Award of the Association for General and Applied Microbiology (VAAM), which is endowed with 10,000 € for outstanding current work in the field of microbiology and will be presented by the VAAM at its annual conference in Würzburg on June 2, 2024.
An enzyme for carbon fixation
The enzyme studied by Rebelein is a nitrogenase. It catalyzes one of the most difficult reactions in nature, the conversion of molecular nitrogen (N2) into ammonia (NH3). To do this, it has to break the strong triple bond of the stable N2. Rebelein showed that nitrogenases surprisingly also reduce CO2 to hydrocarbons. This makes nitrogenases the only biocatalysts in nature that can convert CO2 directly into usable hydrocarbon chains.
Three nitrogenases perform important tasks in the bacterial cell: molybdenum (Mo), vanadium (V) and iron (Fe) nitrogenase (shown as superheroes) break the stable triple bond in molecular nitrogen (N2). In addition, the three nitrogenases also convert CO and CO2 to hydrocarbons (such as methane and ethene) and to formic acid. These are the starting materials for a sustainable bioeconomy. Source: Rebelein, https://doi.org/10.1002/cbic.202100674
To date, three different nitrogenases are known. Last year, Rebelein and his team elucidated the structure of the little-studied iron (Fe) nitrogenase. This enzyme complex from the purple bacterium Rhodobacter capsulatus has a special architecture and eight iron atoms in its active center. “Nitrogenase consists of two symmetrical halves that ‘communicate’ with each other,” explains Rebelein. This enables it to simultaneously reduce CO2 to formic acid (formate) and methane in the two active centers. “This calls into question our entire understanding of nitrogenases, because Fe nitrogenase is obviously also a CO2 reductase ‘in normal bacterial life’.”
The two products of Fe-nitrogenase serve as a food source for other microorganisms. Above all, however, they are of great value for the bioeconomy, for example for the production of green fuels and plastics. As the bacterium Rhodobacter capsulatus generates energy from sunlight in a similar way to plants, it could use light to convert carbon waste into chemicals. This offers solutions for a carbon-neutral and sustainable society. “First of all, we need to fully understand the energy and metabolism of R. capsulatus,” says Rebelein. In the next step, the group wants to modify and improve the nitrogenase and optimize the metabolic pathways.
He has developed and established his own model system for nitrogenase research. His current publications in renowned journals provide new insights into the nitrogenase structure, but also into the life of Rhodobacter capsulatus. Further exciting publications are in the pipeline. The VAAM also emphasizes Rebelein's commitment to the institute. The award committee praises: "Johannes Rebelein is characterized in particular by commitment, independence and the ability to implement - this is exactly what the VAAM Research Award is intended for".
The iron nitrogenase complex,
shown as an electron density map. Source: Rebelein
Dr. Johannes G. Rebelein (37) is an Emmy Noether Junior Research Group Leader at the Max Planck Institute for Terrestrial Microbiology and the SYNMIKRO Research Center in Marburg. He studied biotechnology at the TU Braunschweig and received his doctorate in 2016 under Prof. Dr. Markus W. Ribbe at the University of California in Irvine (USA). This was followed by a postdoc with Prof. Dr. Thomas Ward at the University of Basel (Switzerland).
Information: https://www.mpi-marburg.mpg.de/859249/Johannes_Rebelein
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