Article Dans Une Revue Environmental Science and Technology Année : 2021

Demethylation of Methylmercury in Bird, Fish, and Earthworm

Résumé

Toxicity of methylmercury (MeHg) to wildlife and humans results from its binding to cysteine residues of proteins, forming MeHg-cysteinate (MeHgCys) complexes that hinder biological functions. MeHgCys complexes can be detoxified in vivo, yet how this occurs is unknown. We report that MeHgCys complexes are transformed into selenocysteinate [Hg(Sec)4] complexes in multiple animals from two phyla (a waterbird, freshwater fish, and earthworms) sampled in different geographical areas and contaminated by different Hg sources. In addition, high energy-resolution X-ray absorption spectroscopy (HR-XANES) and chromatography-inductively coupled plasma mass spectrometry of the waterbird liver support the binding of Hg(Sec)4 to selenoprotein P and biomineralization of Hg(Sec)4 to chemically inert nanoparticulate mercury selenide (HgSe). The results provide a foundation for understanding mercury detoxification in higher organisms and suggest that the identified MeHgCys to Hg(Sec)4 demethylation pathway is common in nature.

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hal-03144112 , version 1 (20-03-2021)

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Alain Manceau, Jean-Paul Bourdineaud, Ricardo Oliveira, Sandra L.F. Sarrazin, David Krabbenhoft, et al.. Demethylation of Methylmercury in Bird, Fish, and Earthworm. Environmental Science and Technology, 2021, 55 (3), pp.1527-1534. ⟨10.1021/acs.est.0c04948⟩. ⟨hal-03144112⟩
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