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bioRxiv · 10.1101/2023.12.13.568471

Electron-bifurcation and fluoride efflux systems in Acetobacterium spp. drive defluorination of perfluorinated unsaturated carboxylic acids

Yu, Y.·Xu, F.·Zhao, W.·Thoma, C.·Che, S.·Richman, J. E.·Jin, B.·Zhu, Y.·Xing, Y.·Wackett, L.·Men, Y.
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Abstract

Enzymatic cleavage of C-F bonds in per- and polyfluoroalkyl substances (PFAS) is largely unknown but avidly sought to promote systems biology for PFAS bioremediation. Here, we report the reductive defluorination of , {beta}-unsaturated per- and polyfluorocarboxylic acids by Acetobacterium spp. Two critical molecular features in Acetobacterium species enabling reductive defluorination are (i) a functional fluoride efflux transporter (CrcB) and (ii) an electron-bifurcating caffeate reduction pathway (CarABCDE). The fluoride transporter was required for detoxification of released fluoride. Car enzymes were implicated in defluorination by the following evidence: (i) only Acetobacterium spp. with car genes catalyzed defluorination; (ii) caffeate and PFAS competed in vivo; (iii) models from the X-ray structure of the electron-bifurcating reductase (CarC) positioned the PFAS substrate optimally for reductive defluorination; (iv) products identified by 19F-NMR and high-resolution mass spectrometry were consistent with the model. Defluorination biomarkers identified here were found in wastewater treatment plant metagenomes on six continents.

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Yu, Y., Xu, F., Zhao, W., Thoma, C., Che, S., Richman, J. E., Jin, B., Zhu, Y., Xing, Y., Wackett, L., Men, Y.. 2023-12-13. Electron-bifurcation and fluoride efflux systems in Acetobacterium spp. drive defluorination of perfluorinated unsaturated carboxylic acids. https://doi.org/10.1101/2023.12.13.568471

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