Determination of the Intracellular Complexation of Inorganic and Methylmercury in Cyanobacterium Synechocystis sp. PCC 6803

Article Article scientifique Article Determination of the Intracellular Complexation of Inorganic and Methylmercury in Cyanobacterium Synechocystis sp. PCC 6803 eng 2021-09-30 2021-09-30 author Garcia Calleja Javier 0000-0003-0366-6839 971813 author Cossart Thibaut 0000-0001-6090-9898 895034 author Pedrero Zoyne author Santos João 0000-0002-1899-2226 916877 author Ouerdane Laurent author Tessier Emmanuel author Slaveykova Vera 0000-0002-8361-2509 510054 author Amouroux David 13971-13979 10.1021/acs.est.1c01732 34591446 0013-936X https://pubs.acs.org/doi/10.1021/acs.est.1c01732 Understanding of mercury (Hg) complexation with low molecular weight (LMW) bioligands will help elucidate its speciation. In natural waters, the rate of this complexation is governed by physicochemical, geochemical and biochemical parameters. However, the role of bioligands involved in Hg intracellular handling by aquatic microorganisms is not well documented. Here, we combine the use of isotopically-labelled Hg species (inorganic and monomethyl mercury, iHg & MeHg) with hyphenated techniques based on gas or liquid chromatography coupling to elemental and molecular mass spectrometry to explore the role of intracellular biogenic ligands involved in iHg and MeHg speciation in cyanobacterium Synechocystis sp. PCC 6803, a representative phytoplankton species. The experiment was carried out at low Hg concentration (3 nM / 600 ng L-1 199iHg & 0.3 nM / 60 ng L-1 Me201Hg), one of the lowest reported so far for Hg species incubation with photosynthetic unicellular organisms. This approach allowed us to track resulting metabolic and newly-found intracellular Hg biocomplexes (e.g. organic thiols) in Synechocystis sp. PCC 6803. In the cytosolic fraction, we found different Hg species binding affinities with both high and low molecular weight (HMW & LMW) bioligands after 5 minutes and 24 hours of Hg exposure in the exponential and stationary phase. Furthermore, the parallel detection with both elemental and molecular ionization sources allowed the sensitive detection and molecular identification of glutathione (GSH) as the main low molecular weight binding ligand to iHg ((GS)2-Hg) and MeHg (GS-MeHg) in the cytosolic fraction. Such novel experimental approach expands our knowledge on the role of biogenic ligands involved in iHg and MeHg intracellular handling in cyanobacterium. Hg speciation LMW thiols Cyanobacteria Glutathione Mass spectrometry Phytoplankton Dewey 333.7-333.9 Dewey 550 French National Research Agency (ANR) Elucidating the role of phytoplankton in aquatic mercury (Hg) biotic and abiotic transformations ANR-17-CE34-0014 PHYTAMBA FR Swiss National Science Foundation Elucidating the role of PHYToplankton in Aquatic Mercury (Hg) Biotic and Abiotic transformations (PHYTAMBA) 200021E_175721 CH Project funding 18 Institut des sciences de l'environnement 0DB 41 Département F.-A. Forel des sciences de l'environnement et de l'eau 153 false 752 Environmental Biogeochemistry and Ecotoxicology 944 ISE Eau 938 ISE Pôle Sciences Environmental science & technology 55 20 a4937155-25c4-4b70-9481-e3569bd83d15 Article (Accepted version) Public Garcia_et_all_EST_21R.pdf 899141 application/pdf Restricted 2022-10-01 d1dc2c04-d8fe-4a2e-8e77-3e3befc3b1e7 Article (Published version) Restricted acs.est.1c01732.pdf 1494706 application/pdf openAccess Centres et instituts / Institut des sciences de l'environnement Faculté des sciences / Section des sciences de la Terre et de l'Environnement / Département F.-A. Forel des sciences de l'environnement et de l'eau

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Determination of the Intracellular Complexation of Inorganic and Methylmercury in Cyanobacterium Synechocystis sp. PCC 6803	Environmental science & technology			2021	281	389

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Garcia Calleja, Javier