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5. Unravelling biogeochemical drivers of methylmercury production in an Arctic fen soil and a bog soil

Author

Zhang, Lijie, Philben, Michael, Taş, Neslihan, Johs, Alexander, Yang, Ziming, Wullschleger, Stan D, Graham, David E, Pierce, Eric M, and Gu, Baohua

Subjects
Environmental Sciences, Pollution and Contamination, Life Below Water, Mercury, Methylmercury Compounds, Microbiota, Soil, Soil Pollutants, Wetlands, Methylation, Acetate, Sulfate, Microbial community, Syntrophy
Abstract

Arctic tundra soils store a globally significant amount of mercury (Hg), which could be transformed to the neurotoxic methylmercury (MeHg) upon warming and thus poses serious threats to the Arctic ecosystem. However, our knowledge of the biogeochemical drivers of MeHg production is limited in these soils. Using substrate addition (acetate and sulfate) and selective microbial inhibition approaches, we investigated the geochemical drivers and dominant microbial methylators in 60-day microcosm incubations with two tundra soils: a circumneutral fen soil and an acidic bog soil, collected near Nome, Alaska, United States. Results showed that increasing acetate concentration had negligible influences on MeHg production in both soils. However, inhibition of sulfate-reducing bacteria (SRB) completely stalled MeHg production in the fen soil in the first 15 days, whereas addition of sulfate in the low-sulfate bog soil increased MeHg production by 5-fold, suggesting prominent roles of SRB in Hg(II) methylation. Without the addition of sulfate in the bog soil or when sulfate was depleted in the fen soil (after 15 days), both SRB and methanogens contributed to MeHg production. Analysis of microbial community composition confirmed the presence of several phyla known to harbor microorganisms associated with Hg(II) methylation in the soils. The observations suggest that SRB and methanogens were mainly responsible for Hg(II) methylation in these tundra soils, although their relative contributions depended on the availability of sulfate and possibly syntrophic metabolisms between SRB and methanogens.

Published
2022

6. Structure determination of the HgcAB complex using metagenome sequence data: insights into microbial mercury methylation.

Author

Cooper, Connor J, Zheng, Kaiyuan, Rush, Katherine W, Johs, Alexander, Sanders, Brian C, Pavlopoulos, Georgios A, Kyrpides, Nikos C, Podar, Mircea, Ovchinnikov, Sergey, Ragsdale, Stephen W, and Parks, Jerry M

Abstract

Bacteria and archaea possessing the hgcAB gene pair methylate inorganic mercury (Hg) to form highly toxic methylmercury. HgcA consists of a corrinoid binding domain and a transmembrane domain, and HgcB is a dicluster ferredoxin. However, their detailed structure and function have not been thoroughly characterized. We modeled the HgcAB complex by combining metagenome sequence data mining, coevolution analysis, and Rosetta structure calculations. In addition, we overexpressed HgcA and HgcB in Escherichia coli, confirmed spectroscopically that they bind cobalamin and [4Fe-4S] clusters, respectively, and incorporated these cofactors into the structural model. Surprisingly, the two domains of HgcA do not interact with each other, but HgcB forms extensive contacts with both domains. The model suggests that conserved cysteines in HgcB are involved in shuttling HgII, methylmercury, or both. These findings refine our understanding of the mechanism of Hg methylation and expand the known repertoire of corrinoid methyltransferases in nature.

Published
2020

11. A hidden demethylation pathway removes mercury from rice plants and mitigates mercury flux to food chains

Author

Tang, Wenli, primary, Bai, Xu, additional, Zhou, Yang, additional, Sonne, Christian, additional, Wu, Mengjie, additional, Lam, Su Shiung, additional, Hintelmann, Holger, additional, Mitchell, Carl P. J., additional, Johs, Alexander, additional, Gu, Baohua, additional, Nunes, Luís, additional, Liu, Cun, additional, Feng, Naixian, additional, Yang, Sihai, additional, Rinklebe, Jörg, additional, Lin, Yan, additional, Chen, Long, additional, Zhang, Yanxu, additional, Yang, Yanan, additional, Wang, Jiaqi, additional, Li, Shouying, additional, Wu, Qingru, additional, Ok, Yong Sik, additional, Xu, Diandou, additional, Li, Hong, additional, Zhang, Xu-Xiang, additional, Ren, Hongqiang, additional, Jiang, Guibin, additional, Chai, Zhifang, additional, Gao, Yuxi, additional, Zhao, Jiating, additional, and Zhong, Huan, additional

Published
2024
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14. Structure and Dynamics of a Compact State of a Multidomain Protein, the Mercuric Ion Reductase

Author

Hong, Liang, Sharp, Melissa A, Poblete, Simón, Biehl, Ralf, Zamponi, Michaela, Szekely, Noemi, Appavou, Marie-Sousai, Winkler, Roland G, Nauss, Rachel E, Johs, Alexander, Parks, Jerry M, Yi, Zheng, Cheng, Xiaolin, Liang, Liyuan, Ohl, Michael, Miller, Susan M, Richter, Dieter, Gompper, Gerhard, and Smith, Jeremy C

Subjects
Biochemistry and Cell Biology, Chemical Sciences, Biological Sciences, Amino Acid Sequence, Catalytic Domain, Molecular Sequence Data, Neutron Diffraction, Oxidoreductases, Protein Binding, Scattering, Small Angle, Static Electricity, Physical Sciences, Biophysics, Biological sciences, Chemical sciences, Physical sciences
Abstract

The functional efficacy of colocalized, linked protein domains is dependent on linker flexibility and system compaction. However, the detailed characterization of these properties in aqueous solution presents an enduring challenge. Here, we employ a novel, to our knowledge, combination of complementary techniques, including small-angle neutron scattering, neutron spin-echo spectroscopy, and all-atom molecular dynamics and coarse-grained simulation, to identify and characterize in detail the structure and dynamics of a compact form of mercuric ion reductase (MerA), an enzyme central to bacterial mercury resistance. MerA possesses metallochaperone-like N-terminal domains (NmerA) tethered to its catalytic core domain by linkers. The NmerA domains are found to interact principally through electrostatic interactions with the core, leashed by the linkers so as to subdiffuse on the surface over an area close to the core C-terminal Hg(II)-binding cysteines. How this compact, dynamical arrangement may facilitate delivery of Hg(II) from NmerA to the core domain is discussed.

Published
2014

16. Mercury Remediation Technology Development for Lower East Fork Poplar Creek—FY 2021 Update

Author

Mathews, Teresa, primary, Mayes, Melanie, additional, Brooks, Scott, additional, Derolph, Christopher, additional, Johs, Alexander, additional, Surendrannair, Sujithkumar, additional, Ku, Peijia, additional, Gonez Rodriguez, Leroy, additional, Stevenson, Louise, additional, Matson, Paul, additional, Martinez Collado, Jose, additional, Lowe, Kenneth, additional, Larson, Matt, additional, Duncan, Andrew, additional, Geeza, Tom, additional, Alo, Olawale, additional, and Jones, Nikki, additional

Published
2021
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18. Mercury Remediation Technology Development for Lower East Fork Poplar Creek (FY2020 Update)

Author

Mathews, Teresa, primary, Mayes, Melanie, additional, Brooks, Scott, additional, Derolph, Christopher, additional, Johs, Alexander, additional, Surendrannair, Sujithkumar, additional, Goñez-Rodríguez, Leroy, additional, Pouil, Simon, additional, Stevenson, Louise, additional, Hills, Amber, additional, Matson, Paul, additional, and Martínez Collado, José, additional

Published
2020
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19. First Experiments: New Science Opportunities at the Spallation Neutron Source Second Target Station (abridged)

Author

Adams, Paul, primary, Ankner, John, additional, Anovitz, Lawrence {Larry}, additional, Banerjee, Arnab, additional, Begoli, Edmon, additional, Boehler, Reinhard, additional, Calder, Stuart, additional, Chakoumakos, Bryan, additional, Charlton, Timothy, additional, Chen, Wei-Ren, additional, Cheng, Yongqiang, additional, Coates, Leighton, additional, Cuneo, Matthew, additional, Daemen, Luke, additional, Dela Cruz, Clarina, additional, Do, Changwoo, additional, Moreira dos Santos, Antonio, additional, Dudney, Nancy, additional, Ehlers, Georg, additional, Fitzsimmons, Michael, additional, Gallmeier, Franz, additional, Geist II, Al, additional, Graves, Van, additional, Haberl, Bianca, additional, He, Lilin, additional, Heller, William, additional, Herwig, Kenneth, additional, Hodges, Jason, additional, Hoffmann, Christina, additional, Hong, Kunlun, additional, Huq, Ashfia, additional, Johs, Alexander, additional, Kalluri, Udaya, additional, Katsaras, John, additional, Kolesnikov, Alexander, additional, Kovalevskyi, Andrii, additional, Labbe, Jesse or Jessy, additional, Liu, Jue, additional, Mamontov, Eugene, additional, Manley, Michael, additional, McDonnell, Marshall, additional, McGuire, Michael, additional, Myles, Dean, additional, Nagler, Stephen, additional, Neuefeind, Joerg, additional, Olds, Daniel, additional, Page, Katharine, additional, Payzant, Andrew, additional, Petridis, Loukas, additional, Pingali, Sai Venkatesh, additional, Qian, Shuo, additional, Ramirez Cuesta, Anibal, additional, Roberto, James, additional, Robertson, Lee, additional, Rosenblad, Peter, additional, Saito, Tomonori, additional, Sala, Gabriele, additional, Smith, Gregory, additional, Stanley, Christopher, additional, Stoica, Alexandru, additional, Tennant, Alan, additional, Tulk, Christopher, additional, Usher-Ditzian, Tedi-Marie, additional, Vazhkudai, Sudharshan, additional, Warren, Jeffrey, additional, Wang, Hsiu-Wen, additional, Wang, Zhe, additional, Wesolowski, David, additional, and Williams, Travis, additional

Published
2020
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20. First Experiments: New Science Opportunities at the Spallation Neutron Source Second Target Station

Author

Adams, Paul, primary, Ankner, John, additional, Anovitz, Lawrence (Larry), additional, Banerjee, Arnab, additional, Begoli, Edmon, additional, Bilheux, Hassina, additional, Billings, Jay, additional, Boehler, Reinhard, additional, Calder, Stuart, additional, Chakoumakos, Bryan, additional, Charlton, Timothy, additional, Chen, Wei-Ren, additional, Cheng, Yongqiang, additional, Coates, Leighton, additional, Cuneo, Matthew, additional, Daemen, Luke, additional, Dela Cruz, Clarina, additional, Do, Changwoo, additional, Moreira dos Santos, Antonio, additional, Dudney, Nancy, additional, Ehlers, Georg, additional, Fitzsimmons, Michael, additional, Gallmeier, Franz, additional, Geist II, Al, additional, Graves, Van, additional, Haberl, Bianca, additional, He, Lilin, additional, Heller, William, additional, Herwig, Kenneth, additional, Hodges, Jason, additional, Hoffmann, Christina, additional, Hong, Kunlun, additional, Huq, Ashfia, additional, Johs, Alexander, additional, Kalluri, Udaya, additional, Katsaras, John, additional, Kolesnikov, Alexander, additional, Kovalevskyi, Andrii, additional, Labbe, Jesse or Jessy, additional, Liu, Jue, additional, Mamontov, Eugene, additional, Manley, Michael, additional, McDonnell, Marshall, additional, McGuire, Michael, additional, Myles, Dean, additional, Nagler, Stephen, additional, Neuefeind, Joerg, additional, Olds, Daniel, additional, Page, Katharine, additional, Payzant, Andrew, additional, Petridis, Loukas, additional, Pingali, Sai Venkatesh, additional, Qian, Shuo, additional, Ramirez Cuesta, Anibal, additional, Roberto, James, additional, Robertson, Lee, additional, Rosenblad, Peter, additional, Saito, Tomonori, additional, Sala, Gabriele, additional, Smith, Gregory, additional, Stanley, Christopher, additional, Stoica, Alexandru, additional, Tennant, Alan, additional, Tulk, Christopher, additional, Usher-Ditzian, Tedi-Marie, additional, Vazhkudai, Sudharshan, additional, Warren, Jeffrey, additional, Wang, Hsiu-Wen, additional, Wang, Zhe, additional, Wesolowski, David, additional, and Williams, Travis, additional

Published
2019
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21. Crystal lattice defects in nanocrystalline metacinnabar in contaminated streambank soils suggest a role for biogenic sulfides in the formation of mercury sulfide phases

Author

Koenigsmark, Faye, primary, Chiu, Michelle, additional, Rivera, Nelson, additional, Johs, Alexander, additional, Eskelsen, Jeremy, additional, Leonard, Donovan, additional, Robertson, Boakai K., additional, Szynkiewicz, Anna, additional, Derolph, Christopher, additional, Zhao, Linduo, additional, Gu, Baohua, additional, Hsu-Kim, Heileen, additional, and Pierce, Eric M., additional

Published
2023
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24. The Genetic Basis for Bacterial Mercury Methylation

Author

Parks, Jerry M., Johs, Alexander, Podar, Mircea, Bridou, Romain, Hurt, Richard A., Smith, Steven D., Tomanicek, Stephen J., Qian, Yun, Brown, Steven D., Brandt, Craig C., Palumbo, Anthony V., Smith, Jeremy C., Wall, Judy D., Elias, Dwayne A., and Liang, Liyuan

Published
2013
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27. Mercury Remediation Technology Development for Lower East Fork Poplar Creek—FY 2017 Progress Report

Author

Peterson, Mark J., primary, Mayes, Melanie A., additional, Brooks, Scott C., additional, Mathews, Teresa J., additional, Johs, Alexander, additional, Rodriguez, Leroy Gonez, additional, DeRolph, Christopher R., additional, Pierce, Eric M., additional, Watson, David B., additional, Muller, Katherine A., additional, Olsen, Todd A., additional, Lowe, Kenneth Alan, additional, McManamay, Ryan A., additional, Smith, John G., additional, Morris, Jesse G., additional, and Jones, Michael W., additional

Published
2018
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30. Mercury Remediation Technology Development for Lower East Fork Poplar Creek - FY 2016 Progress Report

Author

Dickson, Johnbull O., primary, Smith, John G., additional, Mehlhorn, Tonia L., additional, Peterson, Mark J., additional, Lowe, Kenneth Alan, additional, Watson, David B., additional, Brooks, Scott C., additional, Morris, Jesse G., additional, Mayes, Melanie, additional, Johs, Alexander, additional, Mathews, Teresa J., additional, McManamay, Ryan A., additional, DeRolph, Christopher R., additional, Poteat, Monica D., additional, Olsen, Todd A., additional, Eller, Virginia A., additional, and Gonez Rodriguez, Leroy, additional

Published
2017
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33. Mercury Remediation Technology Development for Lower East Fork Poplar Creek - FY 2015 Progress Report

Author

Peterson, Mark J., primary, Brooks, Scott C., additional, Mathews, Teresa J., additional, Mayes, Melanie, additional, Johs, Alexander, additional, Watson, David B., additional, Poteat, Monica D., additional, Smith, John, additional, Mehlhorn, Tonia, additional, Lester, Brian, additional, Morris, Jesse, additional, Lowe, Kenneth, additional, Dickson, Johnbull O., additional, Eller, Virginia, additional, and DeRolph, Christopher R., additional

Published
2016
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36. Mercury in Water

Author

Gu, Baohua, primary, Lu, Xia, additional, Johs, Alexander, additional, and Pierce, Eric M., additional

Published
2019
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38. Kinetics of enzymatic mercury methylation at nanomolar concentrations catalyzed by HgcAB: Supplementary information

Author

Date, Swapneeta S, Parks, Jerry M., Rush, Katherine W., Wall, Judy D., Ragsdale, Stephen W., and Johs, Alexander

Abstract

Methylmercury (MeHg) is a potent neurotoxin that bioaccumulates in fish. MeHg is generated by anaerobic bacteria and archaea possessing the gene pair hgcAB. Although bacterial mercury (Hg) methylation has been characterized in vivo, the specific role of HgcAB in catalyzing Hg methylation is not well understood. Here we report the kinetics of HgcAB-mediated Hg methylation in cell lysates of Desulfovibrio desulfuricans ND132 at nanomolar Hg concentrations. The enzymatic Hg methylation mediated by HgcAB is highly oxygen-sensitive, irreversible, and follows Michaelis-Menten kinetics with an apparent KM of 3.2 nM and Vmax of 19.7 fmol.min-1.mg-1 total protein for the substrate Hg(II). Although the abundance of HgcAB in the cell lysates is extremely low, Hg(II) was quantitatively converted to MeHg at sub-nanomolar substrate concentrations. Supplementation with ATP, methyltetrahydrofolate, or pyruvate did not enhance MeHg production under the experimental conditions. Insight into the kinetics of Hg methylation catalyzed by HgcAB advances our understanding of the complex global Hg cycle.

Published
2019
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39. Mercury Reduction, Uptake, and Species Transformation by Freshwater Alga Chlorella vulgarisunder Sunlit and Dark Conditions

Author

Liang, Xujun, Zhu, Nali, Johs, Alexander, Chen, Hongmei, Pelletier, Dale A., Zhang, Lijie, Yin, Xixiang, Gao, Yuxi, Zhao, Jiating, and Gu, Baohua

Abstract

As a major entry point of mercury (Hg) to aquatic food webs, algae play an important role in taking up and transforming Hg species in aquatic ecosystems. However, little is known how and to what extent Hg reduction, uptake, and species transformations are mediated by algal cells and their exudates, algal organic matter (AOM), under either sunlit or dark conditions. Here, using Chlorella vulgaris(CV) as one of the most prevalent freshwater model algal species, we show that solar irradiation could enhance the reduction of mercuric Hg(II) to elemental Hg(0) by both CV cells and AOM. AOM reduced more Hg(II) than algal cells themselves due to cell surface adsorption and uptake of Hg(II) inside the cells under solar irradiation. Synchrotron radiation X-ray absorption near-edge spectroscopy (SR-XANES) analyses indicate that sunlight facilitated the transformation of Hg to less bioavailable species, such as β-HgS and Hg-phytochelatins, compared to Hg(Cysteine)2-like species formed in algal cells in the dark. These findings highlight important functional roles and potential mechanisms of algae in Hg reduction and immobilization under varying lighting conditions and how these processes may modulate Hg cycling and bioavailability in the aquatic environment.

Published
2022
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47. Cover Feature: Laying Waste to Mercury: Inexpensive Sorbents Made from Sulfur and Recycled Cooking Oils (Chem. Eur. J. 64/2017)

Author

Worthington, Max J. H., primary, Kucera, Renata L., additional, Albuquerque, Inês S., additional, Gibson, Christopher T., additional, Sibley, Alexander, additional, Slattery, Ashley D., additional, Campbell, Jonathan A., additional, Alboaiji, Salah F. K., additional, Muller, Katherine A., additional, Young, Jason, additional, Adamson, Nick, additional, Gascooke, Jason R., additional, Jampaiah, Deshetti, additional, Sabri, Ylias M., additional, Bhargava, Suresh K., additional, Ippolito, Samuel J., additional, Lewis, David A., additional, Quinton, Jamie S., additional, Ellis, Amanda V., additional, Johs, Alexander, additional, Bernardes, Gonçalo J. L., additional, and Chalker, Justin M., additional

Published
2017
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48. Laying Waste to Mercury: Inexpensive Sorbents Made from Sulfur and Recycled Cooking Oils

Author

Worthington, Max J. H., primary, Kucera, Renata L., additional, Albuquerque, Inês S., additional, Gibson, Christopher T., additional, Sibley, Alexander, additional, Slattery, Ashley D., additional, Campbell, Jonathan A., additional, Alboaiji, Salah F. K., additional, Muller, Katherine A., additional, Young, Jason, additional, Adamson, Nick, additional, Gascooke, Jason R., additional, Jampaiah, Deshetti, additional, Sabri, Ylias M., additional, Bhargava, Suresh K., additional, Ippolito, Samuel J., additional, Lewis, David A., additional, Quinton, Jamie S., additional, Ellis, Amanda V., additional, Johs, Alexander, additional, Bernardes, Gonçalo J. L., additional, and Chalker, Justin M., additional

Published
2017
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