Thomas, SA, Mishra, B and Myneni, SCB (2020) Cellular Mercury Coordination Environment, and Not Cell Surface Ligands, Influence Bacterial Methylmercury Production. Environmental Science & Technology, 54 (7). pp. 3960-3968. ISSN 0013-936X
Abstract
The conversion of inorganic mercury (Hg(II)) to methylmercury (MeHg) is central to the understanding of Hg toxicity in the environment. Hg methylation occurs in the cytosol of certain obligate anaerobic bacteria and archaea possessing the hgcAB gene cluster. However, the processes involved in Hg(II) biouptake and methylation are not well understood. Here, we examined the role of cell surface thiols, cellular ligands with the highest affinity for Hg(II) that are located at the interface between the outer membrane and external medium, on the sorption and methylation of Hg(II) by Geobacter sulfurreducens. The effect of added cysteine (Cys), which is known to greatly enhance Hg(II) biouptake and methylation, was also explored. By quantitatively blocking surface thiols with a thiol binding ligand (qBBr), we show that surface thiols have no significant effect on Hg(II) methylation, regardless of Cys addition. The results also identify a significant amount of cell-associated Hg-S₃/S₄ species, as studied by high energy-resolution X-ray absorption near edge structure (HR-XANES) spectroscopy, under conditions of high MeHg production (with Cys addition). In contrast, Hg-S₂ are the predominant species during low MeHg production. Hg-S₃/S₄ species may be related to enhanced Hg(II) biouptake or the ability of Hg(II) to become methylated by HgcAB and should be further explored in this context.
Metadata
Item Type: | Article |
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Authors/Creators: |
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Copyright, Publisher and Additional Information: | © 2020 American Chemical Society. This is an author produced version of a paper published in Environmental Science & Technology. Uploaded in accordance with the publisher's self-archiving policy. |
Dates: |
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Institution: | The University of Leeds |
Academic Units: | The University of Leeds > Faculty of Engineering & Physical Sciences (Leeds) > School of Chemical & Process Engineering (Leeds) |
Depositing User: | Symplectic Publications |
Date Deposited: | 27 May 2020 13:41 |
Last Modified: | 25 Feb 2021 01:39 |
Status: | Published |
Publisher: | American Chemical Society (ACS) |
Identification Number: | 10.1021/acs.est.9b05915 |
Open Archives Initiative ID (OAI ID): | oai:eprints.whiterose.ac.uk:161039 |