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bioRxiv · 10.1101/2024.07.29.605569

Carbon monoxide-driven bioethanol production operates via a tungsten-dependent catalyst

Lemaire, O. N.·Belhamri, M.·Shevchenko, A.·Wagner, T.
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Abstract

Microbial alcohol production from waste gasses is a game changer for sustainable carbon cycling and remediation. While the biotechnological process employing Clostridium autoethanogenum to transform syngas (H2/CO2/CO) is blooming, the reactions involved in ethanol biosynthesis remain to be demonstrated. Here, we experimentally showed that ethanol production initiates via a tungsten-dependent aldehyde:ferredoxin oxidoreductase (AFOR), which reduces acetate to acetaldehyde. Such an unfavourable reaction has often been considered unsuitable for a biological process. To answer this riddle, we demonstrated that the thermodynamic pull of CO-oxidation and ethanol synthesis is crucial for triggering acetate reduction. The experimental setup performed with native CO-dehydrogenase and AFOR highlighted the key role of ferredoxin in stimulating the activity of both metalloenzymes and electron shuttling. The crystal structure of holo AFOR refined to 1.59-[A] resolution, together with its biochemical characterisation, provides new insights into the reaction mechanism and the specificities of this enzyme fundamental to sustainable biofuel production.

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Lemaire, O. N., Belhamri, M., Shevchenko, A., Wagner, T.. 2024-07-29. Carbon monoxide-driven bioethanol production operates via a tungsten-dependent catalyst. https://doi.org/10.1101/2024.07.29.605569

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