1
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Yu Y, Li YP, Ren K, Hao X, Fru EC, Rønn R, Rivera WL, Becker K, Feng R, Yang J, Rensing C. A brief history of metal recruitment in protozoan predation. Trends Microbiol 2024; 32:465-476. [PMID: 38103995 DOI: 10.1016/j.tim.2023.11.008] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2023] [Revised: 11/20/2023] [Accepted: 11/23/2023] [Indexed: 12/19/2023]
Abstract
Metals and metalloids are used as weapons for predatory feeding by unicellular eukaryotes on prokaryotes. This review emphasizes the role of metal(loid) bioavailability over the course of Earth's history, coupled with eukaryogenesis and the evolution of the mitochondrion to trace the emergence and use of the metal(loid) prey-killing phagosome as a feeding strategy. Members of the genera Acanthamoeba and Dictyostelium use metals such as zinc (Zn) and copper (Cu), and possibly metalloids, to kill their bacterial prey after phagocytosis. We provide a potential timeline on when these capacities first evolved and how they correlate with perceived changes in metal(loid) bioavailability through Earth's history. The origin of phagotrophic eukaryotes must have postdated the Great Oxidation Event (GOE) in agreement with redox-dependent modification of metal(loid) bioavailability for phagotrophic poisoning. However, this predatory mechanism is predicted to have evolved much later - closer to the origin of the multicellular metazoans and the evolutionary development of the immune systems.
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Affiliation(s)
- Yanshuang Yu
- Institute of Environmental Microbiology, College of Resources and Environment, Fujian Agriculture and Forestry University, Fuzhou, Fujian 350002, China
| | - Yuan-Ping Li
- Institute of Environmental Microbiology, College of Resources and Environment, Fujian Agriculture and Forestry University, Fuzhou, Fujian 350002, China
| | - Kexin Ren
- Aquatic EcoHealth Group, Fujian Key Laboratory of Watershed Ecology, Key Laboratory of Urban Environment and Health, Institute of Urban Environment, Chinese Academy of Sciences, Xiamen 361021, China
| | - Xiuli Hao
- Hubei Key Laboratory of Soil Environment and Pollution Remediation, Huazhong Agricultural University, Wuhan 430070, China
| | - Ernest Chi Fru
- Centre for Geobiology and Geochemistry, School of Earth and Ocean Sciences, Cardiff University, CF10 3AT Cardiff, UK
| | - Regin Rønn
- Department of Biology, University of Copenhagen, Copenhagen, Denmark
| | - Windell L Rivera
- Pathogen-Host-Environment Interactions Research Laboratory, Institute of Biology, College of Science, University of the Philippines Diliman, Quezon City 1101, Philippines
| | - Karsten Becker
- Friedrich Loeffler-Institute for Medical Microbiology, University Medicine Greifswald, D-17489 Greifswald, Germany
| | - Renwei Feng
- Institute of Environmental Microbiology, College of Resources and Environment, Fujian Agriculture and Forestry University, Fuzhou, Fujian 350002, China
| | - Jun Yang
- Aquatic EcoHealth Group, Fujian Key Laboratory of Watershed Ecology, Key Laboratory of Urban Environment and Health, Institute of Urban Environment, Chinese Academy of Sciences, Xiamen 361021, China.
| | - Christopher Rensing
- Institute of Environmental Microbiology, College of Resources and Environment, Fujian Agriculture and Forestry University, Fuzhou, Fujian 350002, China.
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Ge ZB, Zhai ZQ, Xie WY, Dai J, Huang K, Johnson DR, Zhao FJ, Wang P. Two-tiered mutualism improves survival and competitiveness of cross-feeding soil bacteria. THE ISME JOURNAL 2023; 17:2090-2102. [PMID: 37737252 PMCID: PMC10579247 DOI: 10.1038/s41396-023-01519-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/21/2023] [Revised: 09/08/2023] [Accepted: 09/13/2023] [Indexed: 09/23/2023]
Abstract
Metabolic cross-feeding is a pervasive microbial interaction type that affects community stability and functioning and directs carbon and energy flows. The mechanisms that underlie these interactions and their association with metal/metalloid biogeochemistry, however, remain poorly understood. Here, we identified two soil bacteria, Bacillus sp. BP-3 and Delftia sp. DT-2, that engage in a two-tiered mutualism. Strain BP-3 has low utilization ability of pyruvic acid while strain DT-2 lacks hexokinase, lacks a phosphotransferase system, and is defective in glucose utilization. When strain BP-3 is grown in isolation with glucose, it releases pyruvic acid to the environment resulting in acidification and eventual self-killing. However, when strain BP-3 is grown together with strain DT-2, strain DT-2 utilizes the released pyruvic acid to meet its energy requirements, consequently rescuing strain BP-3 from pyruvic acid-induced growth inhibition. The two bacteria further enhance their collective competitiveness against other microbes by using arsenic as a weapon. Strain DT-2 reduces relatively non-toxic methylarsenate [MAs(V)] to highly toxic methylarsenite [MAs(III)], which kills or suppresses competitors, while strain BP-3 detoxifies MAs(III) by methylation to non-toxic dimethylarsenate [DMAs(V)]. These two arsenic transformations are enhanced when strains DT-2 and BP-3 are grown together. The two strains, along with their close relatives, widely co-occur in soils and their abundances increase with the soil arsenic concentration. Our results reveal that these bacterial types employ a two-tiered mutualism to ensure their collective metabolic activity and maintain their ecological competitive against other soil microbes. These findings shed light on the intricateness of bacterial interactions and their roles in ecosystem functioning.
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Affiliation(s)
- Zhan-Biao Ge
- Jiangsu Collaborative Innovation Center for Solid Organic Waste Resource Utilization, College of Resources and Environmental Sciences, Nanjing Agricultural University, Nanjing, 210095, China
- Centre for Agriculture and Health, Academy for Advanced Interdisciplinary Studies, Nanjing Agricultural University, Nanjing, 210095, China
| | - Zhi-Qiang Zhai
- Jiangsu Collaborative Innovation Center for Solid Organic Waste Resource Utilization, College of Resources and Environmental Sciences, Nanjing Agricultural University, Nanjing, 210095, China
- Centre for Agriculture and Health, Academy for Advanced Interdisciplinary Studies, Nanjing Agricultural University, Nanjing, 210095, China
| | - Wan-Ying Xie
- Jiangsu Collaborative Innovation Center for Solid Organic Waste Resource Utilization, College of Resources and Environmental Sciences, Nanjing Agricultural University, Nanjing, 210095, China
| | - Jun Dai
- Jiangsu Collaborative Innovation Center for Solid Organic Waste Resource Utilization, College of Resources and Environmental Sciences, Nanjing Agricultural University, Nanjing, 210095, China
| | - Ke Huang
- Jiangsu Collaborative Innovation Center for Solid Organic Waste Resource Utilization, College of Resources and Environmental Sciences, Nanjing Agricultural University, Nanjing, 210095, China
| | - David R Johnson
- Department of Environmental Microbiology, Swiss Federal Institute of Aquatic Science and Technology (Eawag), 8600, Dübendorf, Switzerland
- Institute of Ecology and Evolution, University of Bern, 3012, Bern, Switzerland
| | - Fang-Jie Zhao
- Jiangsu Collaborative Innovation Center for Solid Organic Waste Resource Utilization, College of Resources and Environmental Sciences, Nanjing Agricultural University, Nanjing, 210095, China
| | - Peng Wang
- Jiangsu Collaborative Innovation Center for Solid Organic Waste Resource Utilization, College of Resources and Environmental Sciences, Nanjing Agricultural University, Nanjing, 210095, China.
- Centre for Agriculture and Health, Academy for Advanced Interdisciplinary Studies, Nanjing Agricultural University, Nanjing, 210095, China.
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3
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Chraiki I, Chi Fru E, Somogyi A, Bouougri EH, Bankole O, Ghnahalla M, El Albani A. Blooming of a microbial community in an Ediacaran extreme volcanic lake system. Sci Rep 2023; 13:9080. [PMID: 37277544 DOI: 10.1038/s41598-023-36031-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2023] [Accepted: 05/27/2023] [Indexed: 06/07/2023] Open
Abstract
Ancient aquatic sediments are critical archives for studying early microbial life and the types of environments in which they thrived. The recently characterized Amane Tazgart microbialites in the Anti-Atlas, Morocco, are a rare and well-preserved non-marine deposit that evolved in an alkaline volcanic lake setting during the Ediacaran Period. A multiproxy geochemical toolbox reveals evidence pointing to spatio-temporal ecosystem organization and succession related to changing lake water chemistry. This is marked by secular transition from a cold/dry climate, hypersaline alkaline thermophilic and anoxic-oxic community, to a stable state warm/wet climate fully oxygenated fresh to brackish water ecosystem, predominated by oxygenic stromatolites. Extreme dissolved Arsenic concentrations suggest that these polyextremophiles required robust detoxification mechanisms to circumvent arsenic toxicity and phosphate deficiency. We propose that self-sustaining and versatile anoxic to oxic microbial ecosystems thrived in aquatic continental settings during the Ediacaran Period, when complex life co-evolved with a rise in atmospheric oxygen content.
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Affiliation(s)
- Ibtissam Chraiki
- Department of Geology, Faculty of Sciences-Semlalia, Cadi Ayyad University, Marrakesh, Morocco
| | - Ernest Chi Fru
- Centre for Geobiology and Geochemistry, College of Physical and Engineering Sciences, School of Earth and Environmental Sciences, Cardiff University, Cardiff, UK
| | - Andrea Somogyi
- Nanoscopium Beamline Synchrotron Soleil, Saint-Aubin, 91192, Gif-sur-Yvette, France
| | - El Hafid Bouougri
- Department of Geology, Faculty of Sciences-Semlalia, Cadi Ayyad University, Marrakesh, Morocco
| | - Olabode Bankole
- CNRS IC2MP UMR 7285, University of Poitiers, Poitiers, France
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Mizio K, Wawrzycka D, Staszewski J, Wysocki R, Maciaszczyk-Dziubinska E. Identification of amino acid substitutions that toggle substrate selectivity of the yeast arsenite transporter Acr3. JOURNAL OF HAZARDOUS MATERIALS 2023; 456:131653. [PMID: 37224717 DOI: 10.1016/j.jhazmat.2023.131653] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/30/2023] [Revised: 05/03/2023] [Accepted: 05/15/2023] [Indexed: 05/26/2023]
Abstract
The Acr3 protein family plays a crucial role in metalloid detoxification and includes members from bacteria to higher plants. Most of the Acr3 transporters studied so far are specific for arsenite, whereas Acr3 from budding yeast also shows some capacity to transport antimonite. However, the molecular basis of Acr3 substrate specificity remains poorly understood. By analyzing randomly generated and rationally designed yeast Acr3 variants, critical residues determining substrate specificity were identified for the first time. Replacement of Val173 with Ala abolished antimonite transport without affecting arsenite extrusion. In contrast, substitution of Glu353 with Asp resulted in a loss of arsenite transport activity and a concomitant increase in antimonite translocation capacity. Importantly, Val173 is located close to the hypothetical substrate binding site, whereas Glu353 has been proposed to participate in substrate binding. Identification of key residues conferring substrate selectivity provides a valuable starting point for further studies of the Acr3 family and may have implications for the development of biotechnological applications in metalloid remediation. Moreover, our data contribute to understanding why members of the Acr3 family evolved as arsenite-specific transporters in an environment of ubiquitously present arsenic and trace amounts of antimony.
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Affiliation(s)
- Katarzyna Mizio
- Department of Genetics and Cell Physiology, Faculty of Biological Sciences, University of Wroclaw, 50-328 Wroclaw, Poland
| | - Donata Wawrzycka
- Department of Genetics and Cell Physiology, Faculty of Biological Sciences, University of Wroclaw, 50-328 Wroclaw, Poland
| | - Jacek Staszewski
- Department of Genetics and Cell Physiology, Faculty of Biological Sciences, University of Wroclaw, 50-328 Wroclaw, Poland
| | - Robert Wysocki
- Department of Genetics and Cell Physiology, Faculty of Biological Sciences, University of Wroclaw, 50-328 Wroclaw, Poland
| | - Ewa Maciaszczyk-Dziubinska
- Department of Genetics and Cell Physiology, Faculty of Biological Sciences, University of Wroclaw, 50-328 Wroclaw, Poland.
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5
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Zhang J, Chen J, Wu YF, Liu X, Packianathan C, Nadar VS, Rosen BP, Zhao FJ. Functional characterization of the methylarsenite-inducible arsRM operon from Noviherbaspirillum denitrificans HC18. Environ Microbiol 2022; 24:772-783. [PMID: 35049138 PMCID: PMC8881391 DOI: 10.1111/1462-2920.15909] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2021] [Revised: 01/12/2022] [Accepted: 01/14/2022] [Indexed: 02/03/2023]
Abstract
Microbial arsenic methylation by arsenite (As(III)) S-adenosylmethionine methyltransferases (ArsMs) can produce the intermediate methylarsenite (MAs(III)), which is highly toxic and is used by some microbes as an antibiotic. Other microbes have evolved mechanisms to detoxify MAs(III). In this study, an arsRM operon was identified in the genome of an MAs(III)-methylation strain Noviherbaspirillum denitrificans HC18. The arsM gene (NdarsM) is located downstream of an open reading frame encoding an MAs(III)-responsive transcriptional regulator (NdArsR). The N. denitrificans arsRM genes are co-transcribed whose expression is significantly induced by MAs(III), likely by alleviating the repressive effect of ArsR on arsRM transcription. Both in vivo and in vitro assays showed that NdArsM methylates MAs(III) to dimethyl- and trimethyl-arsenicals but does not methylate As(III). Heterologous expression of NdarsM in arsenic-sensitive Escherichia coli AW3110 conferred resistance to MAs(III) but not As(III). NdArsM has the four conserved cysteine residues present in most ArsMs, but only two of them are essential for MAs(III) methylation. The ability to methylate MAs(III) by enzymes such as NdArsM may be an evolutionary step originated from enzymes capable of methylating As(III). This finding reveals a mechanism employed by microbes such as N. denitrificans HC18 to detoxify MAs(III) by further methylation.
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Affiliation(s)
- Jun Zhang
- Jiangsu Key Laboratory for Organic Waste Utilization, Jiangsu Collaborative Innovation Center for Solid Organic Waste Resource Utilization, College of Resources and Environmental Sciences, Nanjing Agricultural University, Nanjing 210095, China
| | - Jian Chen
- Department of Cellular Biology and Pharmacology, Herbert Wertheim College of Medicine, Florida International University, Miami, FL 33199, USA
| | - Yi-Fei Wu
- Jiangsu Key Laboratory for Organic Waste Utilization, Jiangsu Collaborative Innovation Center for Solid Organic Waste Resource Utilization, College of Resources and Environmental Sciences, Nanjing Agricultural University, Nanjing 210095, China
| | - Xia Liu
- College of Life Sciences, Nanjing Agricultural University, Nanjing 210095, China
| | - Charles Packianathan
- Department of Cellular Biology and Pharmacology, Herbert Wertheim College of Medicine, Florida International University, Miami, FL 33199, USA
| | - Venkadesh S. Nadar
- Department of Cellular Biology and Pharmacology, Herbert Wertheim College of Medicine, Florida International University, Miami, FL 33199, USA
| | - Barry P. Rosen
- Department of Cellular Biology and Pharmacology, Herbert Wertheim College of Medicine, Florida International University, Miami, FL 33199, USA,Co-corresponding authors: Fangjie Zhao () and Barry P. Rosen ()
| | - Fang-Jie Zhao
- Jiangsu Key Laboratory for Organic Waste Utilization, Jiangsu Collaborative Innovation Center for Solid Organic Waste Resource Utilization, College of Resources and Environmental Sciences, Nanjing Agricultural University, Nanjing 210095, China,Co-corresponding authors: Fangjie Zhao () and Barry P. Rosen ()
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6
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Li YP, Fekih IB, Fru EC, Moraleda-Munoz A, Li X, Rosen BP, Yoshinaga M, Rensing C. Antimicrobial Activity of Metals and Metalloids. Annu Rev Microbiol 2021; 75:175-197. [PMID: 34343021 DOI: 10.1146/annurev-micro-032921-123231] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Competition shapes evolution. Toxic metals and metalloids have exerted selective pressure on life since the rise of the first organisms on the Earth, which has led to the evolution and acquisition of resistance mechanisms against them, as well as mechanisms to weaponize them. Microorganisms exploit antimicrobial metals and metalloids to gain competitive advantage over other members of microbial communities. This exerts a strong selective pressure that drives evolution of resistance. This review describes, with a focus on arsenic and copper, how microorganisms exploit metals and metalloids for predation and how metal- and metalloid-dependent predation may have been a driving force for evolution of microbial resistance against metals and metalloids. Expected final online publication date for the Annual Review of Microbiology, Volume 75 is October 2021. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.
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Affiliation(s)
- Yuan Ping Li
- Institute of Environmental Microbiology, College of Resources and Environment, Fujian Agriculture and Forestry University, Fuzhou 35002, China;
| | - Ibtissem Ben Fekih
- Institute of Environmental Microbiology, College of Resources and Environment, Fujian Agriculture and Forestry University, Fuzhou 35002, China;
| | - Ernest Chi Fru
- Centre for Geobiology and Geochemistry, School of Earth and Ocean Sciences, Cardiff University, CF10 3AT Cardiff, United Kingdom
| | - Aurelio Moraleda-Munoz
- Departamento de Microbiología, Facultad de Ciencias, Universidad de Granada, Granada 18071, Spain
| | - Xuanji Li
- Department of Biology, University of Copenhagen, DK-2200 Copenhagen, Denmark
| | - Barry P Rosen
- Department of Cellular Biology and Pharmacology, Herbert Wertheim College of Medicine, Florida International University, Miami, Florida 33199, USA
| | - Masafumi Yoshinaga
- Department of Cellular Biology and Pharmacology, Herbert Wertheim College of Medicine, Florida International University, Miami, Florida 33199, USA
| | - Christopher Rensing
- Institute of Environmental Microbiology, College of Resources and Environment, Fujian Agriculture and Forestry University, Fuzhou 35002, China;
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7
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Acclimation and adaptation to elevated pCO 2 increase arsenic resilience in marine diatoms. THE ISME JOURNAL 2021; 15:1599-1613. [PMID: 33452476 PMCID: PMC8163839 DOI: 10.1038/s41396-020-00873-y] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/05/2020] [Revised: 11/28/2020] [Accepted: 12/07/2020] [Indexed: 01/29/2023]
Abstract
Arsenic pollution is a widespread threat to marine life, but the ongoing rise pCO2 levels is predicted to decrease bio-toxicity of arsenic. However, the effects of arsenic toxicity on marine primary producers under elevated pCO2 are not well characterized. Here, we studied the effects of arsenic toxicity in three globally distributed diatom species (Phaeodactylum tricornutum, Thalassiosira pseudonana, and Chaetoceros mulleri) after short-term acclimation (ST, 30 days), medium-term exposure (MT, 750 days), and long-term (LT, 1460 days) selection under ambient (400 µatm) and elevated (1000 and 2000 µatm) pCO2. We found that elevated pCO2 alleviated arsenic toxicity even after short acclimation times but the magnitude of the response decreased after mid and long-term adaptation. When fed with these elevated pCO2 selected diatoms, the scallop Patinopecten yessoensis had significantly lower arsenic content (3.26-52.83%). Transcriptomic and biochemical analysis indicated that the diatoms rapidly developed arsenic detoxification strategies, which included upregulation of transporters associated with shuttling harmful compounds out of the cell to reduce arsenic accumulation, and upregulation of proteins involved in synthesizing glutathione (GSH) to chelate intracellular arsenic to reduce arsenic toxicity. Thus, our results will expand our knowledge to fully understand the ecological risk of trace metal pollution under increasing human activity induced ocean acidification.
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8
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Chraiki I, Bouougri EH, Chi Fru E, Lazreq N, Youbi N, Boumehdi A, Aubineau J, Fontaine C, El Albani A. A 571 million-year-old alkaline volcanic lake photosynthesizing microbial community, the Anti-atlas, Morocco. GEOBIOLOGY 2021; 19:105-124. [PMID: 33369021 DOI: 10.1111/gbi.12425] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/03/2020] [Revised: 11/06/2020] [Accepted: 11/30/2020] [Indexed: 06/12/2023]
Abstract
The Ediacaran period coincides with the emergence of ancestral animal lineages and cyanobacteria capable of thriving in nutrient deficient oceans which together with photosynthetic eukaryotic dominance, culminated in the rapid oxygenation of the Ediacaran atmosphere. However, ecological evidence for the colonization of the Ediacaran terrestrial biosphere by photosynthetic communities and their contribution to the oxygenation of the biosphere at this time is very sparse. Here, we expand the repertoire of Ediacaran habitable environments to a specific microbial community that thrived in an extreme alkaline volcanic lake 571 Myr ago in the Anti-atlas of Morocco. The microbial fabrics preserve evidence of primary growth structures, comprised of two main microbialitic units, with the lower section consisting of irregular and patchy thrombolytic mesoclots associated with composite microbialitic domes. Calcirudite interbeds, dominated by wave-rippled sandy calcarenites and stromatoclasts, fill the interdome troughs and seal the dome tops. A meter-thick epiclastic stromatolite bed grading upwards from a dominantly flat to wavy laminated base, transitions into low convex laminae consisting of decimeter to meter-thick dome-shaped stromatolitic columns, overlies the thrombolitic and composite microbialitic facies. Microbialitic beds constructed during periods of limited clastic input, and underlain by coarse-grained microbialite-derived clasts and by the wave-rippled calcarenites, suggest high-energy events associated with lake expansion. High-resolution microscopy revealed spherulitic aggregates and structures reminiscent of coccoidal microbial cell casts and mineralized extra-polymeric substances (EPS). The primary fabrics and multistage diagenetic features, represented by active carbonate production, photosynthesizing microbial communities, photosynthetic gas bubbles, gas escape structures, and tufted mats, suggest specialized oxygenic photosynthesizers thriving in alkaline volcanic lakes, contributed toward oxygen variability in the Ediacaran terrestrial biosphere.
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Affiliation(s)
- Ibtissam Chraiki
- Department of Geology, Faculty of Sciences-Semlalia, Cadi Ayyad University, Marrakesh, Morocco
| | - El Hafid Bouougri
- Department of Geology, Faculty of Sciences-Semlalia, Cadi Ayyad University, Marrakesh, Morocco
| | - Ernest Chi Fru
- Centre for Geobiology and Geochemistry, College of Physical and Engineering Sciences, School of Earth and Ocean Sciences, Cardiff University, Cardiff, UK
| | - Nezha Lazreq
- Department of Geology, Faculty of Sciences-Semlalia, Cadi Ayyad University, Marrakesh, Morocco
| | - Nasrrddine Youbi
- Department of Geology, Faculty of Sciences-Semlalia, Cadi Ayyad University, Marrakesh, Morocco
- Instituto Dom Luiz, University of Lisbon, Lisbon, Portugal
- Faculty of Geology and Geography, Tomsk State University, Tomsk, Russia
| | - Ahmed Boumehdi
- Department of Geology, Faculty of Sciences-Semlalia, Cadi Ayyad University, Marrakesh, Morocco
- Instituto Dom Luiz, University of Lisbon, Lisbon, Portugal
| | | | - Claude Fontaine
- CNRS IC2MP UMR 7285, University of Poitiers, Poitiers, France
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9
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Fuchsman CA, Stüeken EE. Using modern low-oxygen marine ecosystems to understand the nitrogen cycle of the Paleo- and Mesoproterozoic oceans. Environ Microbiol 2020; 23:2801-2822. [PMID: 32869502 DOI: 10.1111/1462-2920.15220] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2020] [Revised: 08/25/2020] [Accepted: 08/27/2020] [Indexed: 11/29/2022]
Abstract
During the productive Paleoproterozoic (2.4-1.8 Ga) and less productive Mesoproterozoic (1.8-1.0 Ga), the ocean was suboxic to anoxic and multicellular organisms had not yet evolved. Here, we link geologic information about the Proterozoic ocean to microbial processes in modern low-oxygen systems. High iron concentrations and rates of Fe cycling in the Proterozoic are the largest differences from modern oxygen-deficient zones. In anoxic waters, which composed most of the Paleoproterozoic and ~40% of the Mesoproterozoic ocean, nitrogen cycling dominated. Rates of N2 production by denitrification and anammox were likely linked to sinking organic matter fluxes and in situ primary productivity under anoxic conditions. Additionally autotrophic denitrifiers could have used reduced iron or methane. 50% of the Mesoproterozoic ocean may have been suboxic, promoting nitrification and metal oxidation in the suboxic water and N2 O and N2 production by partial and complete denitrification in anoxic zones in organic aggregates. Sulfidic conditions may have composed ~10% of the Mesoproterozoic ocean focused along continental margins. Due to low nitrate concentrations in offshore regions, anammox bacteria likely dominated N2 production immediately above sulfidic zones, but in coastal regions, higher nitrate concentrations probably promoted complete S-oxidizing autotrophic denitrification at the sulfide interface.
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Affiliation(s)
- Clara A Fuchsman
- Horn Point Laboratory, University of Maryland Center for Environmental Science, Cambridge, MD, 21613, USA
| | - Eva E Stüeken
- School of Earth & Environmental Sciences, University of St Andrews, St Andrews, KY16 9AL, Scotland, UK
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10
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The Great Oxidation Event expanded the genetic repertoire of arsenic metabolism and cycling. Proc Natl Acad Sci U S A 2020; 117:10414-10421. [PMID: 32350143 PMCID: PMC7229686 DOI: 10.1073/pnas.2001063117] [Citation(s) in RCA: 74] [Impact Index Per Article: 18.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
The rise of oxygen on the early Earth about 2.4 billion years ago reorganized the redox cycle of harmful metal(loids), including that of arsenic, which doubtlessly imposed substantial barriers to the physiology and diversification of life. Evaluating the adaptive biological responses to these environmental challenges is inherently difficult because of the paucity of fossil records. Here we applied molecular clock analyses to 13 gene families participating in principal pathways of arsenic resistance and cycling, to explore the nature of early arsenic biogeocycles and decipher feedbacks associated with planetary oxygenation. Our results reveal the advent of nascent arsenic resistance systems under the anoxic environment predating the Great Oxidation Event (GOE), with the primary function of detoxifying reduced arsenic compounds that were abundant in Archean environments. To cope with the increased toxicity of oxidized arsenic species that occurred as oxygen built up in Earth's atmosphere, we found that parts of preexisting detoxification systems for trivalent arsenicals were merged with newly emerged pathways that originated via convergent evolution. Further expansion of arsenic resistance systems was made feasible by incorporation of oxygen-dependent enzymatic pathways into the detoxification network. These genetic innovations, together with adaptive responses to other redox-sensitive metals, provided organisms with novel mechanisms for adaption to changes in global biogeocycles that emerged as a consequence of the GOE.
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11
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Prabaharan C, Kandavelu P, Packianathan C, Rosen BP, Thiyagarajan S. Structures of two ArsR As(III)-responsive transcriptional repressors: Implications for the mechanism of derepression. J Struct Biol 2019; 207:209-217. [PMID: 31136796 DOI: 10.1016/j.jsb.2019.05.009] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2019] [Revised: 05/23/2019] [Accepted: 05/24/2019] [Indexed: 10/26/2022]
Abstract
ArsR As(III)-responsive transcriptional repressors, members of the ArsR/SmtB family of metalloregulatory proteins, have been characterized biochemically but, to date, no As(III)-bound structure has been solved. Here we report two crystal structures of ArsR repressors from Acidithiobacillus ferrooxidans (AfArsR) and Corynebacterium glutamicum (CgArsR) in the As(III)-bound form. AfArsR crystallized in P21 space group and diffracted up to 1.86 Å. CgArsR crystallized in P212121 and diffracted up to 1.6 Å. AfArsR showed one As(III) bound in one subunit of the homodimer, while the CgArsR structure showed two As(III) bound with S3 coordination, one in each monomer. Previous studies indicated that in AfArsR As(III) binds to Cys95, Cys96 and Cys102 from the same monomer, while, in CgArsR, to Cys15, Cys16 from one monomer and Cys55 from the other monomer. The dimer interfaces of these structures showed distinct differences from other members of the ArsR/SmtB family of proteins, which potentially renders multiple options for evolving metal(loid) binding sites in this family of proteins. Also, CgArsR presents a new α2-N binding site, not the previously predicted α3-N site. Despite differences in the location of the binding cysteines in the primary sequences of these proteins, the two metal binding sites are almost congruent on their structures, an example of convergent evolution. Analyses of the electrostatic surface of the proteins at the DNA binding domain indicate that there two different modes of derepression in the ArsR/SmtB family of metalloregulatory proteins.
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Affiliation(s)
| | - Palani Kandavelu
- SER-CAT, Department of Biochemistry and Molecular Biology, University of Georgia, Athens, GA 30602, USA.
| | - Charles Packianathan
- Department of Cellular Biology and Pharmacology, Herbert Wertheim College of Medicine, Florida International University, Miami, FL 33199, USA.
| | - Barry P Rosen
- Department of Cellular Biology and Pharmacology, Herbert Wertheim College of Medicine, Florida International University, Miami, FL 33199, USA.
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12
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Complete arsenic-based respiratory cycle in the marine microbial communities of pelagic oxygen-deficient zones. Proc Natl Acad Sci U S A 2019; 116:9925-9930. [PMID: 31036654 DOI: 10.1073/pnas.1818349116] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Microbial capacity to metabolize arsenic is ancient, arising in response to its pervasive presence in the environment, which was largely in the form of As(III) in the early anoxic ocean. Many biological arsenic transformations are aimed at mitigating toxicity; however, some microorganisms can respire compounds of this redox-sensitive element to reap energetic gains. In several modern anoxic marine systems concentrations of As(V) are higher relative to As(III) than what would be expected from the thermodynamic equilibrium, but the mechanism for this discrepancy has remained unknown. Here we present evidence of a complete respiratory arsenic cycle, consisting of dissimilatory As(V) reduction and chemoautotrophic As(III) oxidation, in the pelagic ocean. We identified the presence of genes encoding both subunits of the respiratory arsenite oxidase AioA and the dissimilatory arsenate reductase ArrA in the Eastern Tropical North Pacific (ETNP) oxygen-deficient zone (ODZ). The presence of the dissimilatory arsenate reductase gene arrA was enriched on large particles (>30 um), similar to the forward bacterial dsrA gene of sulfate-reducing bacteria, which is involved in the cryptic cycling of sulfur in ODZs. Arsenic respiratory genes were expressed in metatranscriptomic libraries from the ETNP and the Eastern Tropical South Pacific (ETSP) ODZ, indicating arsenotrophy is a metabolic pathway actively utilized in anoxic marine water columns. Together these results suggest arsenic-based metabolisms support organic matter production and impact nitrogen biogeochemical cycling in modern oceans. In early anoxic oceans, especially during periods of high marine arsenic concentrations, they may have played a much larger role.
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13
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Chen J, Yoshinaga M, Rosen BP. The antibiotic action of methylarsenite is an emergent property of microbial communities. Mol Microbiol 2019; 111:487-494. [PMID: 30520200 PMCID: PMC6370046 DOI: 10.1111/mmi.14169] [Citation(s) in RCA: 39] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/14/2018] [Indexed: 11/30/2022]
Abstract
Arsenic is the most ubiquitous environmental toxin. Here, we demonstrate that bacteria have evolved the ability to use arsenic to gain a competitive advantage over other bacteria at least twice. Microbes generate toxic methylarsenite (MAs(III)) by methylation of arsenite (As(III)) or reduction of methylarsenate (MAs(V)). MAs(III) is oxidized aerobically to MAs(V), making methylation a detoxification process. MAs(V) is continually re-reduced to MAs(III) by other community members, giving them a competitive advantage over sensitive bacteria. Because generation of a sustained pool of MAs(III) requires microbial communities, these complex interactions are an emergent property. We show that reduction of MAs(V) by Burkholderia sp. MR1 produces toxic MAs(III) that inhibits growth of Escherichia coli in mixed culture. There are three microbial mechanisms for resistance to MAs(III). ArsH oxidizes MAs(III) to MAs(V). ArsI degrades MAs(III) to As(III). ArsP confers resistance by efflux. Cells of E. coli expressing arsI, arsH or arsP grow in mixed culture with Burkholderia sp. MR1 in the presence of MAs(V). Thus MAs(III) has antibiotic properties: a toxic organic compound produced by one microbe to kill off competitors. Our results demonstrate that life has adapted to use environmental arsenic as a weapon in the continuing battle for dominance.
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Affiliation(s)
- Jian Chen
- Department of Cellular Biology and Pharmacology, Herbert Wertheim
College of Medicine, Florida International University, Miami, Florida 33199,
United States
| | - Masafumi Yoshinaga
- Department of Cellular Biology and Pharmacology, Herbert Wertheim
College of Medicine, Florida International University, Miami, Florida 33199,
United States
| | - Barry P. Rosen
- Department of Cellular Biology and Pharmacology, Herbert Wertheim
College of Medicine, Florida International University, Miami, Florida 33199,
United States
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14
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Fru EC, Callac N, Posth NR, Argyraki A, Ling YC, Ivarsson M, Broman C, Kilias SP. Arsenic and high affinity phosphate uptake gene distribution in shallow submarine hydrothermal sediments. BIOGEOCHEMISTRY 2018; 141:41-62. [PMID: 30956374 PMCID: PMC6413627 DOI: 10.1007/s10533-018-0500-8] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/01/2018] [Accepted: 09/14/2018] [Indexed: 05/27/2023]
Abstract
The toxicity of arsenic (As) towards life on Earth is apparent in the dense distribution of genes associated with As detoxification across the tree of life. The ability to defend against As is particularly vital for survival in As-rich shallow submarine hydrothermal ecosystems along the Hellenic Volcanic Arc (HVA), where life is exposed to hydrothermal fluids containing up to 3000 times more As than present in seawater. We propose that the removal of dissolved As and phosphorus (P) by sulfide and Fe(III)(oxyhydr)oxide minerals during sediment-seawater interaction, produces nutrient-deficient porewaters containing < 2.0 ppb P. The porewater arsenite-As(III) to arsenate-As(V) ratios, combined with sulfide concentration in the sediment and/or porewater, suggest a hydrothermally-induced seafloor redox gradient. This gradient overlaps with changing high affinity phosphate uptake gene abundance. High affinity phosphate uptake and As cycling genes are depleted in the sulfide-rich settings, relative to the more oxidizing habitats where mainly Fe(III)(oxyhydr)oxides are precipitated. In addition, a habitat-wide low As-respiring and As-oxidizing gene content relative to As resistance gene richness, suggests that As detoxification is prioritized over metabolic As cycling in the sediments. Collectively, the data point to redox control on Fe and S mineralization as a decisive factor in the regulation of high affinity phosphate uptake and As cycling gene content in shallow submarine hydrothermal ecosystems along the HVA.
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Affiliation(s)
- Ernest Chi Fru
- Department of Geological Sciences and Bolin Center for Climate Research, Stockholm University, 106 91 Stockholm, Sweden
- College of Physical Sciences and Engineering, School of Earth and Ocean Sciences, Geobiology Center, Cardiff University, Park Place, Cardiff, Wales CF10 3AT UK
| | - Nolwenn Callac
- Department of Geological Sciences and Bolin Center for Climate Research, Stockholm University, 106 91 Stockholm, Sweden
| | - Nicole R. Posth
- Department of Biology, Nordic Center for Earth Evolution (NordCEE), Campusvej 55, 5230 Odense M, Denmark
- Department of Geosciences & Natural Resource Management, Geology Section, University of Copenhagen, Øster Voldgade 10, 1350 Copenhagen K, Denmark
| | - Ariadne Argyraki
- Department of Geology and Geoenvironment, National and Kapodistrian University of Athens, Panepistimiopolis Zographou, 157 84 Athens, Greece
| | - Yu-Chen Ling
- College of Physical Sciences and Engineering, School of Earth and Ocean Sciences, Geobiology Center, Cardiff University, Park Place, Cardiff, Wales CF10 3AT UK
| | - Magnus Ivarsson
- Department of Biology, University of Southern Denmark, Campusvej 55, 5230 Odense M, Denmark
| | - Curt Broman
- Department of Geological Sciences and Bolin Center for Climate Research, Stockholm University, 106 91 Stockholm, Sweden
| | - Stephanos P. Kilias
- Department of Geology and Geoenvironment, National and Kapodistrian University of Athens, Panepistimiopolis Zographou, 157 84 Athens, Greece
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15
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Aubineau J, El Albani A, Chi Fru E, Gingras M, Batonneau Y, Buatois LA, Geffroy C, Labanowski J, Laforest C, Lemée L, Mángano MG, Meunier A, Pierson-Wickmann AC, Recourt P, Riboulleau A, Trentesaux A, Konhauser KO. Unusual microbial mat-related structural diversity 2.1 billion years ago and implications for the Francevillian biota. GEOBIOLOGY 2018; 16:476-497. [PMID: 29923673 DOI: 10.1111/gbi.12296] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/15/2018] [Revised: 04/10/2018] [Accepted: 05/08/2018] [Indexed: 06/08/2023]
Abstract
The 2.1-billion-year-old (Ga) Francevillian series in Gabon hosts some of the oldest reported macroscopic fossils of various sizes and shapes, stimulating new debates on the origin, evolution and organization of early complex life. Here, we document ten representative types of exceptionally well-preserved mat-related structures, comprising "elephant-skin" textures, putative macro-tufted microbial mats, domal buildups, flat pyritized structures, discoidal microbial colonies, horizontal mat growth patterns, wrinkle structures, "kinneyia" structures, linear patterns and nodule-like structures. A combination of petrographic analyses, scanning electron microscopy, Raman spectroscopy and organic elemental analyses of carbon-rich laminae and microtexture, indicate a biological origin for these structures. The observed microtextures encompass oriented grains, floating silt-sized quartz grains, concentrated heavy minerals, randomly oriented clays, wavy-crinkly laminae and pyritized structures. Based on comparisons with modern analogues, as well as an average δ13 C organic matter (Corg ) composition of -32.94 ± 1.17‰ (1 standard deviation, SD) with an outlier of -41.26‰, we argue that the mat-related structures contain relicts of multiple carbon pathways including heterotrophic recycling of photosynthetically derived Corg . Moreover, the relatively close association of the macroscopic fossil assemblages to the microbial mats may imply that microbial communities acted as potential benthic O2 oases linked to oxyphototrophic cyanobacterial mats and grazing grounds. In addition, the mat's presence likely improved the preservation of the oldest large colonial organisms, as they are known to strongly biostabilize sediments. Our findings highlight the oldest community assemblage of microscopic and macroscopic biota in the aftermath of the "Great Oxidation Event," widening our understanding of biological organization during Earth's middle age.
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Affiliation(s)
| | | | - Ernest Chi Fru
- School of Earth and Ocean Sciences, Cardiff University, Cardiff, UK
| | - Murray Gingras
- Department of Earth and Atmospheric Sciences, University of Alberta, Edmonton, Alberta, Canada
| | - Yann Batonneau
- UMR CNRS IC2MP 7285, University of Poitiers, Poitiers, France
| | - Luis A Buatois
- Department of Geological Sciences, University of Saskatchewan, Saskatoon, Saskatchewan, Canada
| | - Claude Geffroy
- UMR CNRS IC2MP 7285, University of Poitiers, Poitiers, France
| | | | - Claude Laforest
- UMR CNRS IC2MP 7285, University of Poitiers, Poitiers, France
| | - Laurent Lemée
- UMR CNRS IC2MP 7285, University of Poitiers, Poitiers, France
| | - Maria G Mángano
- Department of Geological Sciences, University of Saskatchewan, Saskatoon, Saskatchewan, Canada
| | - Alain Meunier
- UMR CNRS IC2MP 7285, University of Poitiers, Poitiers, France
| | | | - Philippe Recourt
- UMR 8187 LOG CNRS, University of Lille, ULCO, Villeneuve d'Ascq, France
| | | | - Alain Trentesaux
- UMR 8187 LOG CNRS, University of Lille, ULCO, Villeneuve d'Ascq, France
| | - Kurt O Konhauser
- Department of Earth and Atmospheric Sciences, University of Alberta, Edmonton, Alberta, Canada
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16
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Recurrent horizontal transfer of arsenite methyltransferase genes facilitated adaptation of life to arsenic. Sci Rep 2017; 7:7741. [PMID: 28798375 PMCID: PMC5552862 DOI: 10.1038/s41598-017-08313-2] [Citation(s) in RCA: 51] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2017] [Accepted: 07/07/2017] [Indexed: 12/12/2022] Open
Abstract
The toxic metalloid arsenic has been environmentally ubiquitous since life first arose nearly four billion years ago and presents a challenge for the survival of all living organisms. Its bioavailability has varied dramatically over the history of life on Earth. As life spread, biogeochemical and climate changes cyclically increased and decreased bioavailable arsenic. To elucidate the history of arsenic adaptation across the tree of life, we reconstructed the phylogeny of the arsM gene that encodes the As(III) S-adenosylmethionine (SAM) methyltransferase. Our results suggest that life successfully moved into arsenic-rich environments in the late Archean Eon and Proterozoic Eon, respectively, by the spread of arsM genes. The arsM genes of bacterial origin have been transferred to other kingdoms of life on at least six occasions, and the resulting domesticated arsM genes promoted adaptation to environmental arsenic. These results allow us to peer into the history of arsenic adaptation of life on our planet and imply that dissemination of genes encoding diverse adaptive functions to toxic chemicals permit adaptation to changes in concentrations of environmental toxins over evolutionary history.
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17
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Hao X, Li X, Pal C, Hobman J, Larsson DGJ, Saquib Q, Alwathnani HA, Rosen BP, Zhu YG, Rensing C. Bacterial resistance to arsenic protects against protist killing. Biometals 2017; 30:307-311. [PMID: 28210928 DOI: 10.1007/s10534-017-0003-4] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2017] [Accepted: 02/10/2017] [Indexed: 11/24/2022]
Abstract
Protists kill their bacterial prey using toxic metals such as copper. Here we hypothesize that the metalloid arsenic has a similar role. To test this hypothesis, we examined intracellular survival of Escherichia coli (E. coli) in the amoeba Dictyostelium discoideum (D. discoideum). Deletion of the E. coli ars operon led to significantly lower intracellular survival compared to wild type E. coli. This suggests that protists use arsenic to poison bacterial cells in the phagosome, similar to their use of copper. In response to copper and arsenic poisoning by protists, there is selection for acquisition of arsenic and copper resistance genes in the bacterial prey to avoid killing. In agreement with this hypothesis, both copper and arsenic resistance determinants are widespread in many bacterial taxa and environments, and they are often found together on plasmids. A role for heavy metals and arsenic in the ancient predator-prey relationship between protists and bacteria could explain the widespread presence of metal resistance determinants in pristine environments.
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Affiliation(s)
- Xiuli Hao
- Key Laboratory of Urban Environment and Health, Institute of Urban Environment, Chinese Academy of Sciences, Xiamen, 361021, China
| | - Xuanji Li
- Department of Biology, University of Copenhagen, Copenhagen, Denmark
| | - Chandan Pal
- Department of Infectious Diseases, Institute for Biomedicine, Sahlgrenska Academy, University of Gothenburg, Göteborg, Sweden.,Center for Antibiotic Resistance Research (CARe) at the University of Gothenburg, Göteborg, Sweden
| | - Jon Hobman
- School of Biosciences, The University of Nottingham, Sutton Bonington Campus, Sutton Bonington, Leicestershire, LE12 5RD, UK
| | - D G Joakim Larsson
- Department of Infectious Diseases, Institute for Biomedicine, Sahlgrenska Academy, University of Gothenburg, Göteborg, Sweden.,Center for Antibiotic Resistance Research (CARe) at the University of Gothenburg, Göteborg, Sweden
| | - Quaiser Saquib
- Zoology Department, College of Science, King Saud University, Riyadh, Saudi Arabia.,A.R. Al-Jeraisy Chair for DNA Research, Zoology Department, College of Science, King Saud University, Riyadh, Saudi Arabia
| | - Hend A Alwathnani
- Botany & Microbiology Department, College of Science, King Saud University, Riyadh, Saudi Arabia
| | - Barry P Rosen
- Herbert Wertheim College of Medicine, Florida International University, Miami, FL, USA
| | - Yong-Guan Zhu
- Key Laboratory of Urban Environment and Health, Institute of Urban Environment, Chinese Academy of Sciences, Xiamen, 361021, China.
| | - Christopher Rensing
- Key Laboratory of Urban Environment and Health, Institute of Urban Environment, Chinese Academy of Sciences, Xiamen, 361021, China. .,J. Craig Venter Institute, San Diego, CA, USA. .,Fujian Provincial Key Laboratory of Soil Environmental Health and Regulation, College of Resources and Environment, Fujian Agriculture and Forestry University, Fuzhou, China.
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18
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Abstract
The oxygenation of the atmosphere ∼2.45-2.32 billion years ago (Ga) is one of the most significant geological events to have affected Earth's redox history. Our understanding of the timing and processes surrounding this key transition is largely dependent on the development of redox-sensitive proxies, many of which remain unexplored. Here we report a shift from negative to positive copper isotopic compositions (δ(65)CuERM-AE633) in organic carbon-rich shales spanning the period 2.66-2.08 Ga. We suggest that, before 2.3 Ga, a muted oxidative supply of weathering-derived copper enriched in (65)Cu, along with the preferential removal of (65)Cu by iron oxides, left seawater and marine biomass depleted in (65)Cu but enriched in (63)Cu. As banded iron formation deposition waned and continentally sourced Cu became more important, biomass sampled a dissolved Cu reservoir that was progressively less fractionated relative to the continental pool. This evolution toward heavy δ(65)Cu values coincides with a shift to negative sedimentary δ(56)Fe values and increased marine sulfate after the Great Oxidation Event (GOE), and is traceable through Phanerozoic shales to modern marine settings, where marine dissolved and sedimentary δ(65)Cu values are universally positive. Our finding of an important shift in sedimentary Cu isotope compositions across the GOE provides new insights into the Precambrian marine cycling of this critical micronutrient, and demonstrates the proxy potential for sedimentary Cu isotope compositions in the study of biogeochemical cycles and oceanic redox balance in the past.
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