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Engrola F, Correia MAS, Watson C, Romão CC, Veiros LF, Romão MJ, Santos-Silva T, Santini JM. Arsenite oxidase in complex with antimonite and arsenite oxyanions: Insights into the catalytic mechanism. J Biol Chem 2023; 299:105036. [PMID: 37442232 PMCID: PMC10448176 DOI: 10.1016/j.jbc.2023.105036] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2023] [Revised: 06/27/2023] [Accepted: 07/05/2023] [Indexed: 07/15/2023] Open
Abstract
Arsenic contamination of groundwater is among one of the biggest health threats affecting millions of people in the world. There is an urgent need for efficient arsenic biosensors where the use of arsenic metabolizing enzymes can be explored. In this work, we have solved four crystal structures of arsenite oxidase (Aio) in complex with arsenic and antimony oxyanions and the structures determined correspond to intermediate states of the enzymatic mechanism. These structural data were complemented with density-functional theory calculations providing a unique view of the molybdenum active site at different time points that, together with mutagenesis data, enabled to clarify the enzymatic mechanism and the molecular determinants for the oxidation of As(III) to the less toxic As(V) species.
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Affiliation(s)
- Filipa Engrola
- UCIBIO - Applied Molecular Biosciences Unit, Department of Chemistry, School of Science and Technology, NOVA University Lisbon, Caparica, Portugal; Associate Laboratory i4HB - Institute for Health and Bioeconomy, School of Science and Technology, NOVA University Lisbon, Caparica, Portugal
| | - Márcia A S Correia
- UCIBIO - Applied Molecular Biosciences Unit, Department of Chemistry, School of Science and Technology, NOVA University Lisbon, Caparica, Portugal; Associate Laboratory i4HB - Institute for Health and Bioeconomy, School of Science and Technology, NOVA University Lisbon, Caparica, Portugal
| | - Cameron Watson
- Division of Biosciences, Institute of Structural and Molecular Biology, University College London, London, United Kingdom
| | | | - Luis F Veiros
- Centro de Química Estrutural, Institute of Molecular Sciences, Lisboa, Portugal; Departamento de Engenharia Química, Instituto Superior Técnico, Universidade de Lisboa, Lisboa, Portugal
| | - Maria João Romão
- UCIBIO - Applied Molecular Biosciences Unit, Department of Chemistry, School of Science and Technology, NOVA University Lisbon, Caparica, Portugal; Associate Laboratory i4HB - Institute for Health and Bioeconomy, School of Science and Technology, NOVA University Lisbon, Caparica, Portugal.
| | - Teresa Santos-Silva
- UCIBIO - Applied Molecular Biosciences Unit, Department of Chemistry, School of Science and Technology, NOVA University Lisbon, Caparica, Portugal; Associate Laboratory i4HB - Institute for Health and Bioeconomy, School of Science and Technology, NOVA University Lisbon, Caparica, Portugal.
| | - Joanne M Santini
- Division of Biosciences, Institute of Structural and Molecular Biology, University College London, London, United Kingdom.
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2
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Draft Genome Sequence of Polaromonas eurypsychrophila AER18D-145, Isolated from a Uranium Tailings Management Facility in Northern Saskatchewan, Canada. Microbiol Resour Announc 2022; 11:e0001322. [PMID: 35262382 PMCID: PMC9022503 DOI: 10.1128/mra.00013-22] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The 4.8-Mbp draft genome sequence of Polaromonas eurypsychrophila AER18D-145, isolated from a uranium tailings management facility, is reported. The sequence may provide insights into the mechanisms of the hypertolerance of this strain to extreme conditions and help determine its potential for bioremediation applications.
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3
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Green Oxidation of Amines by a Novel Cold-Adapted Monoamine Oxidase MAO P3 from Psychrophilic Fungi Pseudogymnoascus sp. P3. Molecules 2021; 26:molecules26206237. [PMID: 34684818 PMCID: PMC8538783 DOI: 10.3390/molecules26206237] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2021] [Revised: 10/08/2021] [Accepted: 10/12/2021] [Indexed: 11/17/2022] Open
Abstract
The use of monoamine oxidases (MAOs) in amine oxidation is a great example of how biocatalysis can be applied in the agricultural or pharmaceutical industry and manufacturing of fine chemicals to make a shift from traditional chemical synthesis towards more sustainable green chemistry. This article reports the screening of fourteen Antarctic fungi strains for MAO activity and the discovery of a novel psychrozyme MAOP3 isolated from the Pseudogymnoascus sp. P3. The activity of the native enzyme was 1350 ± 10.5 U/L towards a primary (n-butylamine) amine, and 1470 ± 10.6 U/L towards a secondary (6,6-dimethyl-3-azabicyclohexane) amine. MAO P3 has the potential for applications in biotransformations due to its wide substrate specificity (aliphatic and cyclic amines, pyrrolidine derivatives). The psychrozyme operates at an optimal temperature of 30 °C, retains 75% of activity at 20 °C, and is rather thermolabile, which is beneficial for a reduction in the overall costs of a bioprocess and offers a convenient way of heat inactivation. The reported biocatalyst is the first psychrophilic MAO; its unique biochemical properties, substrate specificity, and effectiveness predispose MAO P3 for use in environmentally friendly, low-emission biotransformations.
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Ziegelhöfer A, Kujala K. Assessing the Diversity and Metabolic Potential of Psychrotolerant Arsenic-Metabolizing Microorganisms From a Subarctic Peatland Used for Treatment of Mining-Affected Waters by Culture-Dependent and -Independent Techniques. Front Microbiol 2021; 12:648412. [PMID: 34295311 PMCID: PMC8290898 DOI: 10.3389/fmicb.2021.648412] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2020] [Accepted: 06/08/2021] [Indexed: 12/22/2022] Open
Abstract
Arsenic contamination in water by natural causes or industrial activities is a major environmental concern, and treatment of contaminated waters is needed to protect water resources and minimize the risk for human health. In mining environments, treatment peatlands are used in the polishing phase of water treatment to remove arsenic (among other contaminants), and peat microorganisms play a crucial role in arsenic removal. The present study assessed culture-independent diversity obtained through metagenomic and metatranscriptomic sequencing and culture-dependent diversity obtained by isolating psychrotolerant arsenic-tolerant, arsenite-oxidizing, and arsenate-respiring microorganisms from a peatland treating mine effluent waters of a gold mine in Finnish Lapland using a dilution-to-extinction technique. Low diversity enrichments obtained after several transfers were dominated by the genera Pseudomonas, Polaromonas, Aeromonas, Brevundimonas, Ancylobacter, and Rhodoferax. Even though maximal growth and physiological activity (i.e., arsenite oxidation or arsenate reduction) were observed at temperatures between 20 and 28°C, most enrichments also showed substantial growth/activity at 2–5°C, indicating the successful enrichments of psychrotolerant microorganisms. After additional purification, eight arsenic-tolerant, five arsenite-oxidizing, and three arsenate-respiring strains were obtained in pure culture and identified as Pseudomonas, Rhodococcus, Microbacterium, and Cadophora. Some of the enriched and isolated genera are not known to metabolize arsenic, and valuable insights on arsenic turnover pathways may be gained by their further characterization. Comparison with phylogenetic and functional data from the metagenome indicated that the enriched and isolated strains did not belong to the most abundant genera, indicating that culture-dependent and -independent methods capture different fractions of the microbial community involved in arsenic turnover. Rare biosphere microorganisms that are present in low abundance often play an important role in ecosystem functioning, and the enriched/isolated strains might thus contribute substantially to arsenic turnover in the treatment peatland. Psychrotolerant pure cultures of arsenic-metabolizing microorganisms from peatlands are needed to close the knowledge gaps pertaining to microbial arsenic turnover in peatlands located in cold climate regions, and the isolates and enrichments obtained in this study are a good starting point to establish model systems. Improved understanding of their metabolism could moreover lead to their use in biotechnological applications intended for bioremediation of arsenic-contaminated waters.
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Affiliation(s)
- Aileen Ziegelhöfer
- Faculty for Chemistry & Biotechnology, Aachen University of Applied Sciences, Jülich, Germany.,Water, Energy and Environmental Engineering Research Unit, University of Oulu, Oulu, Finland
| | - Katharina Kujala
- Water, Energy and Environmental Engineering Research Unit, University of Oulu, Oulu, Finland
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5
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Sun X, Qiu L, Kolton M, Häggblom M, Xu R, Kong T, Gao P, Li B, Jiang C, Sun W. V V Reduction by Polaromonas spp. in Vanadium Mine Tailings. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2020; 54:14442-14454. [PMID: 33125214 DOI: 10.1021/acs.est.0c05328] [Citation(s) in RCA: 30] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/13/2023]
Abstract
Vanadium (V) is an important metal with critical industrial and medical applications. Elevated V contamination, however, can be a threat to the environment and human health. Microorganisms can reduce the more toxic and mobile VV to the less toxic and immobile VIV, which could be a detoxification and energy metabolism strategy adopted by V-reducing bacteria (VRB). The limited understanding of microbial responses to V contamination and the mechanisms for VV reduction, however, hamper our capability to attenuate V contamination. This study focused on determining the microbial responses to elevated V concentration and the mechanisms of VV reduction in V tailings. The bacterial communities were characterized and compared between the V tailings and the less contaminated adjacent mineral soils. Further, VV-reducing enrichments indicated that bacteria associated with Polaromonas, a genus belonging to the family Burkholderiaceae, were potentially responsible for VV reduction. Retrieved metagenome-assembled genomes (MAGs) suggested that the Polaromonas spp. encoded genes (cymA, omcA, and narG) were responsible for VV reduction. Additionally, Polaromonas spp. was metabolically versatile and could use both organic and inorganic electron donors. The metabolic versatility of Polaromonas spp. may be important for its ability to flourish in the V tailings.
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Affiliation(s)
- Xiaoxu Sun
- National-Regional Joint Engineering Research Center for Soil Pollution Control and Remediation in South China, Guangdong Key Laboratory of Integrated Agro-environmental Pollution Control and Management, Institute of Eco-environmental and Soil Sciences, Guangdong Academy of Sciences, Guangzhou 510650, China
- Guangdong-Hong Kong-Macao Joint Laboratory for Environmental Pollution and Control, Guangzhou 510650, China
| | - Lang Qiu
- National-Regional Joint Engineering Research Center for Soil Pollution Control and Remediation in South China, Guangdong Key Laboratory of Integrated Agro-environmental Pollution Control and Management, Institute of Eco-environmental and Soil Sciences, Guangdong Academy of Sciences, Guangzhou 510650, China
- Guangdong-Hong Kong-Macao Joint Laboratory for Environmental Pollution and Control, Guangzhou 510650, China
| | - Max Kolton
- National-Regional Joint Engineering Research Center for Soil Pollution Control and Remediation in South China, Guangdong Key Laboratory of Integrated Agro-environmental Pollution Control and Management, Institute of Eco-environmental and Soil Sciences, Guangdong Academy of Sciences, Guangzhou 510650, China
- Guangdong-Hong Kong-Macao Joint Laboratory for Environmental Pollution and Control, Guangzhou 510650, China
| | - Max Häggblom
- Department of Biochemistry and Microbiology, Rutgers University, New Brunswick, New Jersey 08901, United States
| | - Rui Xu
- National-Regional Joint Engineering Research Center for Soil Pollution Control and Remediation in South China, Guangdong Key Laboratory of Integrated Agro-environmental Pollution Control and Management, Institute of Eco-environmental and Soil Sciences, Guangdong Academy of Sciences, Guangzhou 510650, China
- Guangdong-Hong Kong-Macao Joint Laboratory for Environmental Pollution and Control, Guangzhou 510650, China
| | - Tianle Kong
- National-Regional Joint Engineering Research Center for Soil Pollution Control and Remediation in South China, Guangdong Key Laboratory of Integrated Agro-environmental Pollution Control and Management, Institute of Eco-environmental and Soil Sciences, Guangdong Academy of Sciences, Guangzhou 510650, China
- Guangdong-Hong Kong-Macao Joint Laboratory for Environmental Pollution and Control, Guangzhou 510650, China
| | - Pin Gao
- National-Regional Joint Engineering Research Center for Soil Pollution Control and Remediation in South China, Guangdong Key Laboratory of Integrated Agro-environmental Pollution Control and Management, Institute of Eco-environmental and Soil Sciences, Guangdong Academy of Sciences, Guangzhou 510650, China
- Guangdong-Hong Kong-Macao Joint Laboratory for Environmental Pollution and Control, Guangzhou 510650, China
| | - Baoqin Li
- National-Regional Joint Engineering Research Center for Soil Pollution Control and Remediation in South China, Guangdong Key Laboratory of Integrated Agro-environmental Pollution Control and Management, Institute of Eco-environmental and Soil Sciences, Guangdong Academy of Sciences, Guangzhou 510650, China
- Guangdong-Hong Kong-Macao Joint Laboratory for Environmental Pollution and Control, Guangzhou 510650, China
| | - Chengjian Jiang
- State Key Laboratory for Conservation and Utilization of Subtropical Agro-bioresources, Guangxi Research Center for Microbial and Enzyme Engineering Technology, College of Life Science and Technology, Guangxi University, Nanning 530004, China
| | - Weimin Sun
- National-Regional Joint Engineering Research Center for Soil Pollution Control and Remediation in South China, Guangdong Key Laboratory of Integrated Agro-environmental Pollution Control and Management, Institute of Eco-environmental and Soil Sciences, Guangdong Academy of Sciences, Guangzhou 510650, China
- Guangdong-Hong Kong-Macao Joint Laboratory for Environmental Pollution and Control, Guangzhou 510650, China
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6
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Badilla C, Osborne TH, Cole A, Watson C, Djordjevic S, Santini JM. A new family of periplasmic-binding proteins that sense arsenic oxyanions. Sci Rep 2018; 8:6282. [PMID: 29674678 PMCID: PMC5908839 DOI: 10.1038/s41598-018-24591-w] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2018] [Accepted: 04/06/2018] [Indexed: 01/21/2023] Open
Abstract
Arsenic contamination of drinking water affects more than 140 million people worldwide. While toxic to humans, inorganic forms of arsenic (arsenite and arsenate), can be used as energy sources for microbial respiration. AioX and its orthologues (ArxX and ArrX) represent the first members of a new sub-family of periplasmic-binding proteins that serve as the first component of a signal transduction system, that’s role is to positively regulate expression of arsenic metabolism enzymes. As determined by X-ray crystallography for AioX, arsenite binding only requires subtle conformational changes in protein structure, providing insights into protein-ligand interactions. The binding pocket of all orthologues is conserved but this alone is not sufficient for oxyanion selectivity, with proteins selectively binding either arsenite or arsenate. Phylogenetic evidence, clearly demonstrates that the regulatory proteins evolved together early in prokaryotic evolution and had a separate origin from the metabolic enzymes whose expression they regulate.
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Affiliation(s)
- Consuelo Badilla
- Institute of Structural & Molecular Biology, Division of Biosciences, University College London, London, WC1E 6BT, UK
| | - Thomas H Osborne
- Institute of Structural & Molecular Biology, Division of Biosciences, University College London, London, WC1E 6BT, UK
| | - Ambrose Cole
- Institute of Structural & Molecular Biology, Department of Biological Sciences, Birkbeck College, University of London, WC1E 7HX, London, UK
| | - Cameron Watson
- Institute of Structural & Molecular Biology, Division of Biosciences, University College London, London, WC1E 6BT, UK
| | - Snezana Djordjevic
- Institute of Structural & Molecular Biology, Division of Biosciences, University College London, London, WC1E 6BT, UK.
| | - Joanne M Santini
- Institute of Structural & Molecular Biology, Division of Biosciences, University College London, London, WC1E 6BT, UK.
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7
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Chen F, Cao Y, Wei S, Li Y, Li X, Wang Q, Wang G. Regulation of arsenite oxidation by the phosphate two-component system PhoBR in Halomonas sp. HAL1. Front Microbiol 2015; 6:923. [PMID: 26441863 PMCID: PMC4563254 DOI: 10.3389/fmicb.2015.00923] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2015] [Accepted: 08/21/2015] [Indexed: 01/25/2023] Open
Abstract
Previously, the expression of arsenite [As(III)] oxidase genes aioBA was reported to be regulated by a three-component regulatory system, AioXSR, in a number of As(III)-oxidizing bacterial strains. However, the regulation mechanism is still unknown when aioXSR genes are absent in some As(III)-oxidizing bacterial genomes, such as in Halomonas sp. HAL1. In this study, transposon mutagenesis and gene knock-out mutation were performed, and two mutants, HAL1-phoR931 and HAL1-▵phoB, were obtained in strain HAL1. The phoR and phoB constitute a two-component system which is responsible for phosphate (Pi) acquisition and assimilation. Both of the mutants showed negative As(III)-oxidation phenotypes in low Pi condition (0.1 mM) but not under normal Pi condition (1 mM). The phoBR complementation strain HAL1-▵phoB-C reversed the mutants' null phenotypes back to wild type status. Meanwhile, lacZ reporter fusions using pCM-lacZ showed that the expression of phoBR and aioBA were both induced by As(III) but were not induced in HAL1-phoR931 and HAL1-▵phoB. Using 15 consensus Pho box sequences, a putative Pho box was found in the aioBA regulation region. PhoB was able to bind to the putative Pho box in vivo (bacterial one-hybrid detection) and in vitro (electrophoretic mobility gel shift assay), and an 18-bp binding sequence containing nine conserved bases were determined. This study provided the evidence that PhoBR regulates the expression of aioBA in Halomonas sp. HAL1 under low Pi condition. The new regulation model further implies the close metabolic connection between As and Pi.
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Affiliation(s)
- Fang Chen
- State Key Laboratory of Agricultural Microbiology, Huazhong Agricultural University Wuhan, China
| | - Yajing Cao
- State Key Laboratory of Agricultural Microbiology, Huazhong Agricultural University Wuhan, China
| | - Sha Wei
- State Key Laboratory of Agricultural Microbiology, Huazhong Agricultural University Wuhan, China
| | - Yanzhi Li
- State Key Laboratory of Agricultural Microbiology, Huazhong Agricultural University Wuhan, China
| | - Xiangyang Li
- State Key Laboratory of Agricultural Microbiology, Huazhong Agricultural University Wuhan, China
| | - Qian Wang
- State Key Laboratory of Agricultural Microbiology, Huazhong Agricultural University Wuhan, China
| | - Gejiao Wang
- State Key Laboratory of Agricultural Microbiology, Huazhong Agricultural University Wuhan, China
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8
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Koechler S, Arsène-Ploetze F, Brochier-Armanet C, Goulhen-Chollet F, Heinrich-Salmeron A, Jost B, Lièvremont D, Philipps M, Plewniak F, Bertin PN, Lett MC. Constitutive arsenite oxidase expression detected in arsenic-hypertolerant Pseudomonas xanthomarina S11. Res Microbiol 2015; 166:205-14. [PMID: 25753102 DOI: 10.1016/j.resmic.2015.02.010] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2014] [Revised: 02/05/2015] [Accepted: 02/20/2015] [Indexed: 02/06/2023]
Abstract
Pseudomonas xanthomarina S11 is an arsenite-oxidizing bacterium isolated from an arsenic-contaminated former gold mine in Salsigne, France. This bacterium showed high resistance to arsenite and was able to oxidize arsenite to arsenate at concentrations up to 42.72 mM As[III]. The genome of this strain was sequenced and revealed the presence of three ars clusters. One of them is located on a plasmid and is organized as an "arsenic island" harbouring an aio operon and genes involved in phosphorous metabolism, in addition to the ars genes. Neither the aioXRS genes nor a specific sigma-54-dependent promoter located upstream of aioBA genes, both involved in regulation of arsenite oxidase expression in other arsenite-oxidizing bacteria, could be identified in the genome. This observation is in accordance with the fact that no difference was observed in expression of arsenite oxidase in P. xanthomarina S11, whether or not the strain was grown in the presence of As[III].
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Affiliation(s)
- Sandrine Koechler
- UMR7156 Université de Strasbourg/CNRS Génétique Moléculaire, Génomique, Microbiologie, Département Micro-organismes, Génomes, Environnement, 28 rue Goethe, 67083 Strasbourg Cedex, France.
| | - Florence Arsène-Ploetze
- UMR7156 Université de Strasbourg/CNRS Génétique Moléculaire, Génomique, Microbiologie, Département Micro-organismes, Génomes, Environnement, 28 rue Goethe, 67083 Strasbourg Cedex, France.
| | - Céline Brochier-Armanet
- Université de Lyon, Université Lyon 1, CNRS, UMR5558, Laboratoire de Biométrie et Biologie Evolutive, 43 boulevard du 11 Novembre 1918, F-69622 Villeurbanne, France.
| | - Florence Goulhen-Chollet
- UMR7156 Université de Strasbourg/CNRS Génétique Moléculaire, Génomique, Microbiologie, Département Micro-organismes, Génomes, Environnement, 28 rue Goethe, 67083 Strasbourg Cedex, France.
| | - Audrey Heinrich-Salmeron
- UMR7156 Université de Strasbourg/CNRS Génétique Moléculaire, Génomique, Microbiologie, Département Micro-organismes, Génomes, Environnement, 28 rue Goethe, 67083 Strasbourg Cedex, France.
| | - Bernard Jost
- Plateforme Biopuces et séquençage, IGBMC, 1 rue Laurent Fries Parc d'Innovation, 67400 Illkirch, France.
| | - Didier Lièvremont
- UMR7156 Université de Strasbourg/CNRS Génétique Moléculaire, Génomique, Microbiologie, Département Micro-organismes, Génomes, Environnement, 28 rue Goethe, 67083 Strasbourg Cedex, France.
| | - Muriel Philipps
- Plateforme Biopuces et séquençage, IGBMC, 1 rue Laurent Fries Parc d'Innovation, 67400 Illkirch, France.
| | - Frédéric Plewniak
- UMR7156 Université de Strasbourg/CNRS Génétique Moléculaire, Génomique, Microbiologie, Département Micro-organismes, Génomes, Environnement, 28 rue Goethe, 67083 Strasbourg Cedex, France.
| | - Philippe N Bertin
- UMR7156 Université de Strasbourg/CNRS Génétique Moléculaire, Génomique, Microbiologie, Département Micro-organismes, Génomes, Environnement, 28 rue Goethe, 67083 Strasbourg Cedex, France.
| | - Marie-Claire Lett
- UMR7156 Université de Strasbourg/CNRS Génétique Moléculaire, Génomique, Microbiologie, Département Micro-organismes, Génomes, Environnement, 28 rue Goethe, 67083 Strasbourg Cedex, France.
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9
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Abstract
Arsenic and antimony are toxic metalloids and are considered priority environmental pollutants by the U.S. Environmental Protection Agency. Significant advances have been made in understanding microbe-arsenic interactions and how they influence arsenic redox speciation in the environment. However, even the most basic features of how and why a microorganism detects and reacts to antimony remain poorly understood. Previous work with Agrobacterium tumefaciens strain 5A concluded that oxidation of antimonite [Sb(III)] and arsenite [As(III)] required different biochemical pathways. Here, we show with in vivo experiments that a mutation in aioA [encoding the large subunit of As(III) oxidase] reduces the ability to oxidize Sb(III) by approximately one-third relative to the ability of the wild type. Further, in vitro studies with the purified As(III) oxidase from Rhizobium sp. strain NT-26 (AioA shares 94% amino acid sequence identity with AioA of A. tumefaciens) provide direct evidence of Sb(III) oxidation but also show a significantly decreased Vmax compared to that of As(III) oxidation. The aioBA genes encoding As(III) oxidase are induced by As(III) but not by Sb(III), whereas arsR gene expression is induced by both As(III) and Sb(III), suggesting that detection and transcriptional responses for As(III) and Sb(III) differ. While Sb(III) and As(III) are similar with respect to cellular extrusion (ArsB or Acr3) and interaction with ArsR, they differ in the regulatory mechanisms that control the expression of genes encoding the different Ars or Aio activities. In summary, this study documents an enzymatic basis for microbial Sb(III) oxidation, although additional Sb(III) oxidation activity also is apparent in this bacterium.
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10
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Warelow TP, Oke M, Schoepp-Cothenet B, Dahl JU, Bruselat N, Sivalingam GN, Leimkühler S, Thalassinos K, Kappler U, Naismith JH, Santini JM. The respiratory arsenite oxidase: structure and the role of residues surrounding the rieske cluster. PLoS One 2013; 8:e72535. [PMID: 24023621 PMCID: PMC3758308 DOI: 10.1371/journal.pone.0072535] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2013] [Accepted: 07/10/2013] [Indexed: 11/18/2022] Open
Abstract
The arsenite oxidase (Aio) from the facultative autotrophic Alphaproteobacterium Rhizobium sp. NT-26 is a bioenergetic enzyme involved in the oxidation of arsenite to arsenate. The enzyme from the distantly related heterotroph, Alcaligenes faecalis, which is thought to oxidise arsenite for detoxification, consists of a large α subunit (AioA) with bis-molybdopterin guanine dinucleotide at its active site and a 3Fe-4S cluster, and a small β subunit (AioB) which contains a Rieske 2Fe-2S cluster. The successful heterologous expression of the NT-26 Aio in Escherichia coli has resulted in the solution of its crystal structure. The NT-26 Aio, a heterotetramer, shares high overall similarity to the heterodimeric arsenite oxidase from A. faecalis but there are striking differences in the structure surrounding the Rieske 2Fe-2S cluster which we demonstrate explains the difference in the observed redox potentials (+225 mV vs. +130/160 mV, respectively). A combination of site-directed mutagenesis and electron paramagnetic resonance was used to explore the differences observed in the structure and redox properties of the Rieske cluster. In the NT-26 AioB the substitution of a serine (S126 in NT-26) for a threonine as in the A. faecalis AioB explains a -20 mV decrease in redox potential. The disulphide bridge in the A. faecalis AioB which is conserved in other betaproteobacterial AioB subunits and the Rieske subunit of the cytochrome bc 1 complex is absent in the NT-26 AioB subunit. The introduction of a disulphide bridge had no effect on Aio activity or protein stability but resulted in a decrease in the redox potential of the cluster. These results are in conflict with previous data on the betaproteobacterial AioB subunit and the Rieske of the bc 1 complex where removal of the disulphide bridge had no effect on the redox potential of the former but a decrease in cluster stability was observed in the latter.
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Affiliation(s)
- Thomas P. Warelow
- Institute of Structural and Molecular Biology, University College London, London, United Kingdom
| | - Muse Oke
- Centre for Biomolecular Sciences, University of St Andrews, St Andrews, United Kingdom
| | - Barbara Schoepp-Cothenet
- Laboratoire de Bioénergétique et Ingénierie des Protéines, BIP/CNRS, UMR7281, AMU, Marseille, France
| | - Jan U. Dahl
- Universität Potsdam, Institut für Biochemie and Biologie, Potsdam, Germany
| | - Nicole Bruselat
- Institute of Structural and Molecular Biology, University College London, London, United Kingdom
| | - Ganesh N. Sivalingam
- Institute of Structural and Molecular Biology, University College London, London, United Kingdom
| | - Silke Leimkühler
- Universität Potsdam, Institut für Biochemie and Biologie, Potsdam, Germany
| | - Konstantinos Thalassinos
- Institute of Structural and Molecular Biology, University College London, London, United Kingdom
| | - Ulrike Kappler
- School of Chemistry and Molecular Biosciences, The University of Queensland, St. Lucia, Queensland, Australia
| | - James H. Naismith
- Centre for Biomolecular Sciences, University of St Andrews, St Andrews, United Kingdom
| | - Joanne M. Santini
- Institute of Structural and Molecular Biology, University College London, London, United Kingdom
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11
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Kalimuthu P, Heath MD, Santini JM, Kappler U, Bernhardt PV. Electrochemically driven catalysis of Rhizobium sp. NT-26 arsenite oxidase with its native electron acceptor cytochrome c552. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2013; 1837:112-20. [PMID: 23891971 DOI: 10.1016/j.bbabio.2013.07.010] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/09/2013] [Revised: 07/05/2013] [Accepted: 07/19/2013] [Indexed: 10/26/2022]
Abstract
We describe the catalytic voltammograms of the periplasmic arsenite oxidase (Aio) from the chemolithoautotrophic bacterium Rhizobium sp. str. NT-26 that oxidizes arsenite to arsenate. Electrochemistry of the enzyme was accomplished using its native electron transfer partner, cytochrome c552 (cyt c552), as a mediator. The protein cyt c552 adsorbed on a mercaptoundecanoic acid (MUA) modified Au electrode exhibited a stable, reversible one-electron voltammetric response at +275mV vs NHE (pH6). In the presence of arsenite and Aio the voltammetry of cyt c552 is transformed from a transient response to an amplified sigmoidal (steady state) wave consistent with an electro-catalytic system. Digital simulation was performed using a single set of parameters for all catalytic voltammetries obtained at different sweep rates and various substrate concentrations. The obtained kinetic constants from digital simulation provide new insight into the kinetics of the NT-26 Aio catalytic mechanism.
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Affiliation(s)
- Palraj Kalimuthu
- School of Chemistry and Molecular Biosciences, University of Queensland, Brisbane 4072, Australia
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