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Huo X, Zhou Z, Liu H, Wang G, Shi K. A PadR family transcriptional repressor regulates the transcription of chromate efflux transporter in Enterobacter sp. Z1. J Microbiol 2024; 62:355-365. [PMID: 38587592 DOI: 10.1007/s12275-024-00117-0] [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: 09/25/2023] [Revised: 01/10/2024] [Accepted: 01/23/2024] [Indexed: 04/09/2024]
Abstract
Chromium is a prevalent toxic heavy metal, and chromate [Cr(VI)] exhibits high mutagenicity and carcinogenicity. The presence of the Cr(VI) efflux protein ChrA has been identified in strains exhibiting resistance to Cr(VI). Nevertheless, certain strains of bacteria that are resistant to Cr(VI) lack the presence of ChrB, a known regulatory factor. Here, a PadR family transcriptional repressor, ChrN, has been identified as a regulator in the response of Enterobacter sp. Z1(CCTCC NO: M 2019147) to Cr(VI). The chrN gene is cotranscribed with the chrA gene, and the transcriptional expression of this operon is induced by Cr(VI). The binding capacity of the ChrN protein to Cr(VI) was demonstrated by both the tryptophan fluorescence assay and Ni-NTA purification assay. The interaction between ChrN and the chrAN operon promoter was validated by reporter gene assay and electrophoretic mobility shift assay. Mutation of the conserved histidine residues His14 and His50 resulted in loss of ChrN binding with the promoter of the chrAN operon. This observation implies that these residues are crucial for establishing a DNA-binding site. These findings demonstrate that ChrN functions as a transcriptional repressor, modulating the cellular response of strain Z1 to Cr(VI) exposure.
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Affiliation(s)
- Xueqi Huo
- National Key Laboratory of Agricultural Microbiology, College of Life Science and Technology, Huazhong Agricultural University, Wuhan, 430070, People's Republic of China
| | - Zijie Zhou
- National Key Laboratory of Agricultural Microbiology, College of Life Science and Technology, Huazhong Agricultural University, Wuhan, 430070, People's Republic of China
| | - Hongliang Liu
- School of Life Sciences and Medicine, Shandong University of Technology, Zibo, 255000, Shandong Province, People's Republic of China
| | - Gejiao Wang
- National Key Laboratory of Agricultural Microbiology, College of Life Science and Technology, Huazhong Agricultural University, Wuhan, 430070, People's Republic of China
| | - Kaixiang Shi
- National Key Laboratory of Agricultural Microbiology, College of Life Science and Technology, Huazhong Agricultural University, Wuhan, 430070, People's Republic of China.
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2
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Lan Y, Luo X, Fan X, Wang G, Zheng S, Shi K. Arsenite Mediates Selenite Resistance and Reduction in Enterobacter sp. Z1, Thereby Enhancing Bacterial Survival in Selenium Environments. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2024; 58:4204-4213. [PMID: 38373240 DOI: 10.1021/acs.est.3c08346] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/21/2024]
Abstract
Arsenic (As) is widely present in the environment, and virtually all bacteria possess a conserved ars operon to resist As toxicity. High selenium (Se) concentrations tend to be cytotoxic. Se has an uneven regional distribution and is added to mitigate As contamination in Se-deficient areas. However, the bacterial response to exogenous Se remains poorly understood. Herein, we found that As(III) presence was crucial for Enterobacter sp. Z1 to develop resistance against Se(IV). Se(IV) reduction served as a detoxification mechanism in bacteria, and our results demonstrated an increase in the production of Se nanoparticles (SeNPs) in the presence of As(III). Tandem mass tag proteomics analysis revealed that the induction of As(III) activated the inositol phosphate, butanoyl-CoA/dodecanoyl-CoA, TCA cycle, and tyrosine metabolism pathways, thereby enhancing bacterial metabolism to resist Se(IV). Additionally, arsHRBC, sdr-mdr, purHD, and grxA were activated to participate in the reduction of Se(IV) into SeNPs. Our findings provide innovative perspectives for exploring As-induced Se biotransformation in prokaryotes.
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Affiliation(s)
- Yan Lan
- National Key Laboratory of Agricultural Microbiology, College of Life Science and Technology, Huazhong Agricultural University, Wuhan 430070, China
| | - Xiong Luo
- National Key Laboratory of Agricultural Microbiology, College of Life Science and Technology, Huazhong Agricultural University, Wuhan 430070, China
| | - Xia Fan
- College of Biology and Agricultural Resources, Huanggang Normal University, Huanggang 438000, Hubei, China
| | - Gejiao Wang
- National Key Laboratory of Agricultural Microbiology, College of Life Science and Technology, Huazhong Agricultural University, Wuhan 430070, China
| | - Shixue Zheng
- National Key Laboratory of Agricultural Microbiology, College of Life Science and Technology, Huazhong Agricultural University, Wuhan 430070, China
| | - Kaixiang Shi
- National Key Laboratory of Agricultural Microbiology, College of Life Science and Technology, Huazhong Agricultural University, Wuhan 430070, China
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3
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Huang Z, Zou J, Guo M, Zhang G, Gao J, Zhao H, Yan F, Niu Y, Wang GL. An aerotaxis receptor influences invasion of Agrobacterium tumefaciens into its host. PeerJ 2024; 12:e16898. [PMID: 38332807 PMCID: PMC10851874 DOI: 10.7717/peerj.16898] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2023] [Accepted: 01/16/2024] [Indexed: 02/10/2024] Open
Abstract
Agrobacterium tumefaciens is a soil-borne pathogenic bacterium that causes crown gall disease in many plants. Chemotaxis offers A. tumefaciens the ability to find its host and establish infection. Being an aerobic bacterium, A. tumefaciens possesses one chemotaxis system with multiple potential chemoreceptors. Chemoreceptors play an important role in perceiving and responding to environmental signals. However, the studies of chemoreceptors in A. tumefaciens remain relatively restricted. Here, we characterized a cytoplasmic chemoreceptor of A. tumefaciens C58 that contains an N-terminal globin domain. The chemoreceptor was designated as Atu1027. The deletion of Atu1027 not only eliminated the aerotactic response of A. tumefaciens to atmospheric air but also resulted in a weakened chemotactic response to multiple carbon sources. Subsequent site-directed mutagenesis and phenotypic analysis showed that the conserved residue His100 in Atu1027 is essential for the globin domain's function in both chemotaxis and aerotaxis. Furthermore, deleting Atu1027 impaired the biofilm formation and pathogenicity of A. tumefaciens. Collectively, our findings demonstrated that Atu1027 functions as an aerotaxis receptor that affects agrobacterial chemotaxis and the invasion of A. tumefaciens into its host.
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Affiliation(s)
- Zhiwei Huang
- Jiangsu Provincial Agricultural Green and Low Carbon Production Technology Engineering Research Center, School of Life Science and Food Engineering, Huaiyin Institute of Technology, Huai’an, Jiangsu Province, China
| | - Junnan Zou
- Jiangsu Provincial Agricultural Green and Low Carbon Production Technology Engineering Research Center, School of Life Science and Food Engineering, Huaiyin Institute of Technology, Huai’an, Jiangsu Province, China
| | - Minliang Guo
- College of Bioscience and Biotechnology, Yangzhou University, Yangzhou City, Jiangsu Province, China
| | - Guoliang Zhang
- Jiangsu Provincial Agricultural Green and Low Carbon Production Technology Engineering Research Center, School of Life Science and Food Engineering, Huaiyin Institute of Technology, Huai’an, Jiangsu Province, China
| | - Jun Gao
- Jiangsu Provincial Agricultural Green and Low Carbon Production Technology Engineering Research Center, School of Life Science and Food Engineering, Huaiyin Institute of Technology, Huai’an, Jiangsu Province, China
| | - Hongliang Zhao
- Jiangsu Provincial Agricultural Green and Low Carbon Production Technology Engineering Research Center, School of Life Science and Food Engineering, Huaiyin Institute of Technology, Huai’an, Jiangsu Province, China
| | - Feiyu Yan
- Jiangsu Provincial Agricultural Green and Low Carbon Production Technology Engineering Research Center, School of Life Science and Food Engineering, Huaiyin Institute of Technology, Huai’an, Jiangsu Province, China
| | - Yuan Niu
- Jiangsu Provincial Agricultural Green and Low Carbon Production Technology Engineering Research Center, School of Life Science and Food Engineering, Huaiyin Institute of Technology, Huai’an, Jiangsu Province, China
| | - Guang-Long Wang
- Jiangsu Provincial Agricultural Green and Low Carbon Production Technology Engineering Research Center, School of Life Science and Food Engineering, Huaiyin Institute of Technology, Huai’an, Jiangsu Province, China
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4
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Cerna‐Vargas JP, Sánchez‐Romera B, Matilla MA, Ortega Á, Krell T. Sensing preferences for prokaryotic solute binding protein families. Microb Biotechnol 2023; 16:1823-1833. [PMID: 37547952 PMCID: PMC10443332 DOI: 10.1111/1751-7915.14292] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2023] [Accepted: 05/25/2023] [Indexed: 08/08/2023] Open
Abstract
Solute binding proteins (SBPs) are of central physiological relevance for prokaryotes. These proteins present substrates to transporters, but they also stimulate different signal transduction receptors. SBPs form a superfamily of at least 33 protein Pfam families. To assess possible links between SBP sequence and the ligand recognized, we have inspected manually all SBP three-dimensional structures deposited in the protein data bank and retrieved 748 prokaryotic structures that have been solved in complex with bound ligand. These structures were classified into 26 SBP Pfam families. The analysis of the ligands recognized revealed that most families possess a preference for a compound class. There were three families each that bind preferentially saccharides and amino acids. In addition, we identified families that bind preferentially purines, quaternary amines, iron and iron-chelating compounds, oxoanions, bivalent metal ions or phosphates. Phylogenetic analyses suggest convergent evolutionary events that lead to families that bind the same ligand. The functional link between chemotaxis and compound uptake is reflected in similarities in the ligands recognized by SBPs and chemoreceptors. Associating Pfam families with ligand profiles will be of help to design experimental strategies aimed at the identification of ligands for uncharacterized SBPs.
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Affiliation(s)
- Jean Paul Cerna‐Vargas
- Department of Biotechnology and Environmental ProtectionEstación Experimental del Zaidín, Consejo Superior de Investigaciones CientíficasGranadaSpain
- Centro de Biotecnología y Genómica de Plantas CBGPUniversidad Politécnica de Madrid‐Instituto Nacional de Investigación y Tecnología Agraria y Alimentaria/CSIC, Parque Científico y Tecnológico de la UPMMadridSpain
| | - Beatriz Sánchez‐Romera
- Scientific Instrumentation ServiceEstación Experimental del Zaidín, Consejo Superior de Investigaciones CientíficasGranadaSpain
| | - Miguel A. Matilla
- Department of Biotechnology and Environmental ProtectionEstación Experimental del Zaidín, Consejo Superior de Investigaciones CientíficasGranadaSpain
| | - Álvaro Ortega
- Department of Biochemistry and Molecular Biology B and Immunology, Faculty of ChemistryUniversity of MurciaMurciaSpain
| | - Tino Krell
- Department of Biotechnology and Environmental ProtectionEstación Experimental del Zaidín, Consejo Superior de Investigaciones CientíficasGranadaSpain
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Mohsin H, Shafique M, Zaid M, Rehman Y. Microbial biochemical pathways of arsenic biotransformation and their application for bioremediation. Folia Microbiol (Praha) 2023:10.1007/s12223-023-01068-6. [PMID: 37326815 DOI: 10.1007/s12223-023-01068-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2022] [Accepted: 05/19/2023] [Indexed: 06/17/2023]
Abstract
Arsenic is a ubiquitous toxic metalloid, the concentration of which is beyond WHO safe drinking water standards in many areas of the world, owing to many natural and anthropogenic activities. Long-term exposure to arsenic proves lethal for plants, humans, animals, and even microbial communities in the environment. Various sustainable strategies have been developed to mitigate the harmful effects of arsenic which include several chemical and physical methods, however, bioremediation has proved to be an eco-friendly and inexpensive technique with promising results. Many microbes and plant species are known for arsenic biotransformation and detoxification. Arsenic bioremediation involves different pathways such as uptake, accumulation, reduction, oxidation, methylation, and demethylation. Each of these pathways has a certain set of genes and proteins to carry out the mechanism of arsenic biotransformation. Based on these mechanisms, various studies have been conducted for arsenic detoxification and removal. Genes specific for these pathways have also been cloned in several microorganisms to enhance arsenic bioremediation. This review discusses different biochemical pathways and the associated genes which play important roles in arsenic redox reactions, resistance, methylation/demethylation, and accumulation. Based on these mechanisms, new methods can be developed for effective arsenic bioremediation.
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Affiliation(s)
- Hareem Mohsin
- Department of Life Sciences, School of Science, University of Management and Technology, Lahore, Pakistan
| | - Maria Shafique
- Institute of Microbiology and Molecular Genetics, University of the Punjab, Quaid-e-Azam Campus, Lahore, Pakistan
| | - Muhammad Zaid
- Department of Life Sciences, School of Science, University of Management and Technology, Lahore, Pakistan
| | - Yasir Rehman
- Department of Life Sciences, School of Science, University of Management and Technology, Lahore, Pakistan.
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Jia X, Zhao K, Liu F, Lin J, Lin C, Chen J. Transcriptional factor OmpR positively regulates prodigiosin biosynthesis in Serratia marcescens FZSF02 by binding with the promoter of the prodigiosin cluster. Front Microbiol 2022; 13:1041146. [PMID: 36466667 PMCID: PMC9712742 DOI: 10.3389/fmicb.2022.1041146] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2022] [Accepted: 11/01/2022] [Indexed: 10/27/2023] Open
Abstract
Prodigiosin is a promising secondary metabolite mainly produced by Serratia marcescens. The production of prodigiosin by S. marcescens is regulated by different kinds of regulatory systems, including the EnvZ/OmpR system. In this study, we demonstrated that the regulatory factor OmpR positively regulated prodigiosin production in S. marcescens FZSF02 by directly binding to the promoter region of the prodigiosin biosynthesis cluster with a lacZ reporter assay and electrophoretic mobility shift assay (EMSA). The binding sequence with the pig promoter was identified by a DNase I footprinting assay. We further demonstrate that OmpR regulates its own expression by directly binding to the promoter region of envZ/ompR. For the first time, the regulatory mechanism of prodigiosin production by the transcriptional factor OmpR was revealed.
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Affiliation(s)
- Xianbo Jia
- Institute of Soil and Fertilizer, Fujian Academy of Agricultural Sciences, Fujian Key Laboratory of Plant Nutrition and Fertilizer, Fuzhou, China
| | - Ke Zhao
- College of Resources and Environment, Fujian Agriculture and Forestry University, Fuzhou, China
| | - Fangchen Liu
- College of Resources and Environment, Fujian Agriculture and Forestry University, Fuzhou, China
| | - Junjie Lin
- College of Life Sciences, Fujian Agriculture and Forestry University, Fuzhou, China
| | - Chenqiang Lin
- Institute of Soil and Fertilizer, Fujian Academy of Agricultural Sciences, Fujian Key Laboratory of Plant Nutrition and Fertilizer, Fuzhou, China
| | - Jichen Chen
- Institute of Soil and Fertilizer, Fujian Academy of Agricultural Sciences, Fujian Key Laboratory of Plant Nutrition and Fertilizer, Fuzhou, China
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7
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Ali S, Tyagi A, Mushtaq M, Al-Mahmoudi H, Bae H. Harnessing plant microbiome for mitigating arsenic toxicity in sustainable agriculture. ENVIRONMENTAL POLLUTION (BARKING, ESSEX : 1987) 2022; 300:118940. [PMID: 35122918 DOI: 10.1016/j.envpol.2022.118940] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/08/2021] [Revised: 01/08/2022] [Accepted: 01/30/2022] [Indexed: 06/14/2023]
Abstract
Heavy metal toxicity has become an impediment to agricultural productivity, which presents major human health concerns in terms of food safety. Among them, arsenic (As) a non-essential heavy metal has gained worldwide attention because of its noxious effects on agriculture and public health. The increasing rate of global warming and anthropogenic activities have promptly exacerbated As levels in the agricultural soil, thereby causing adverse effects to crop genetic and phenotypic traits and rendering them vulnerable to other stresses. Conventional breeding and transgenic approaches have been widely adapted for producing heavy metal resilient crops; however, they are time-consuming and labor-intensive. Hence, finding new mitigation strategies for As toxicity would be a game-changer for sustainable agriculture. One such promising approach is harnessing plant microbiome in the era of 'omics' which is gaining prominence in recent years. The use of plant microbiome and their cocktails to combat As metal toxicity has gained widespread attention, because of their ability to metabolize toxic elements and offer an array of perquisites to host plants such as increased nutrient availability, stress resilience, soil fertility, and yield. A comprehensive understanding of below-ground plant-microbiome interactions and their underlying molecular mechanisms in exhibiting resilience towards As toxicity will help in identifying elite microbial communities for As mitigation. In this review, we have discussed the effect of As, their accumulation, transportation, signaling, and detoxification in plants. We have also discussed the role of the plant microbiome in mitigating As toxicity which has become an intriguing research frontier in phytoremediation. This review also provides insights on the advancements in constructing the beneficial synthetic microbial communities (SynComs) using microbiome engineering that will facilitate the development of the most advanced As remedial tool kit in sustainable agriculture.
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Affiliation(s)
- Sajad Ali
- Department of Biotechnology, Yeungnam University, Gyeongsan, Gyeongbuk, 38541, Republic of Korea
| | - Anshika Tyagi
- Department of Biotechnology, Yeungnam University, Gyeongsan, Gyeongbuk, 38541, Republic of Korea
| | | | - Henda Al-Mahmoudi
- Directorate of Programs, International Center for Biosaline Agriculture, Dubai, United Arab Emirates
| | - Hanhong Bae
- Department of Biotechnology, Yeungnam University, Gyeongsan, Gyeongbuk, 38541, Republic of Korea.
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8
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Matilla MA, Velando F, Martín-Mora D, Monteagudo-Cascales E, Krell T. A catalogue of signal molecules that interact with sensor kinases, chemoreceptors and transcriptional regulators. FEMS Microbiol Rev 2021; 46:6356564. [PMID: 34424339 DOI: 10.1093/femsre/fuab043] [Citation(s) in RCA: 45] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2021] [Accepted: 08/10/2021] [Indexed: 12/12/2022] Open
Abstract
Bacteria have evolved many different signal transduction systems that sense signals and generate a variety of responses. Generally, most abundant are transcriptional regulators, sensor histidine kinases and chemoreceptors. Typically, these systems recognize their signal molecules with dedicated ligand-binding domains (LBDs), which, in turn, generate a molecular stimulus that modulates the activity of the output module. There are an enormous number of different LBDs that recognize a similarly diverse set of signals. To give a global perspective of the signals that interact with transcriptional regulators, sensor kinases and chemoreceptors, we manually retrieved information on the protein-ligand interaction from about 1,200 publications and 3D structures. The resulting 811 proteins were classified according to the Pfam family into 127 groups. These data permit a delineation of the signal profiles of individual LBD families as well as distinguishing between families that recognize signals in a promiscuous manner and those that possess a well-defined ligand range. A major bottleneck in the field is the fact that the signal input of many signaling systems is unknown. The signal repertoire reported here will help the scientific community design experimental strategies to identify the signaling molecules for uncharacterised sensor proteins.
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Affiliation(s)
- Miguel A Matilla
- Department of Environmental Protection, Estación Experimental del Zaidín, Consejo Superior de Investigaciones Científicas, Prof. Albareda 1, 18008 Granada, Spain
| | - Félix Velando
- Department of Environmental Protection, Estación Experimental del Zaidín, Consejo Superior de Investigaciones Científicas, Prof. Albareda 1, 18008 Granada, Spain
| | - David Martín-Mora
- Department of Environmental Protection, Estación Experimental del Zaidín, Consejo Superior de Investigaciones Científicas, Prof. Albareda 1, 18008 Granada, Spain
| | - Elizabet Monteagudo-Cascales
- Department of Environmental Protection, Estación Experimental del Zaidín, Consejo Superior de Investigaciones Científicas, Prof. Albareda 1, 18008 Granada, Spain
| | - Tino Krell
- Department of Environmental Protection, Estación Experimental del Zaidín, Consejo Superior de Investigaciones Científicas, Prof. Albareda 1, 18008 Granada, Spain
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9
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Shi K, Radhakrishnan M, Dai X, Rosen BP, Wang G. NemA Catalyzes Trivalent Organoarsenical Oxidation and Is Regulated by the Trivalent Organoarsenical-Selective Transcriptional Repressor NemR. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2021; 55:6485-6494. [PMID: 33851826 PMCID: PMC8879406 DOI: 10.1021/acs.est.1c00574] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Synthetic aromatic arsenicals such as roxarsone (Rox(V)) and nitarsone (Nit(V)) have been used as animal growth enhancers and herbicides. Microbes contribute to redox cycling between the relatively less toxic pentavalent and highly toxic trivalent arsenicals. In this study, we report the identification of nemRA operon from Enterobacter sp. Z1 and show that it is involved in trivalent organoarsenical oxidation. Expression of nemA is induced by chromate (Cr(VI)), Rox(III), and Nit(III). Heterologous expression of NemA in Escherichia coli confers resistance to Cr(VI), methylarsenite (MAs(III)), Rox(III), and Nit(III). Purified NemA catalyzes simultaneous Cr(VI) reduction and MAs(III)/Rox(III)/Nit(III) oxidation, and oxidation was enhanced in the presence of Cr(VI). The results of electrophoretic mobility shift assays and fluorescence assays demonstrate that the transcriptional repressor, NemR, binds to either Rox(III) or Nit(III). NemR has three conserved cysteine residues, Cys21, Cys106, and Cys116. Mutation of any of the three resulted in loss of response to Rox(III)/Nit(III), indicating that they form an Rox(III)/Nit(III) binding site. These results show that NemA is a novel trivalent organoarsenical oxidase that is regulated by the trivalent organoarsenical-selective repressor NemR. This discovery expands our knowledge of the molecular mechanisms of organoarsenical oxidation and provides a basis for studying the redox coupling of environmental toxic compounds.
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Affiliation(s)
- Kaixiang Shi
- State Key Laboratory of Agricultural Microbiology, College of Life Science and Technology, Huazhong Agricultural University, Wuhan 430070, P. R. China
- Department of Cellular Biology and Pharmacology, Herbert Wertheim College of Medicine, Florida International University, Miami, Florida 33199, United States
| | - Manohar Radhakrishnan
- Department of Cellular Biology and Pharmacology, Herbert Wertheim College of Medicine, Florida International University, Miami, Florida 33199, United States
| | - Xingli Dai
- State Key Laboratory of Agricultural Microbiology, College of Life Science and Technology, Huazhong Agricultural University, Wuhan 430070, P. R. China
| | - Barry P Rosen
- Department of Cellular Biology and Pharmacology, Herbert Wertheim College of Medicine, Florida International University, Miami, Florida 33199, United States
| | - Gejiao Wang
- State Key Laboratory of Agricultural Microbiology, College of Life Science and Technology, Huazhong Agricultural University, Wuhan 430070, P. R. China
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10
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Yasir M, Zhang Y, Xu Z, Luo M, Wang G. NAD(P)H-dependent thioredoxin-disulfide reductase TrxR is essential for tellurite and selenite reduction and resistance in Bacillus sp. Y3. FEMS Microbiol Ecol 2021; 96:5863184. [PMID: 32589222 DOI: 10.1093/femsec/fiaa126] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2020] [Accepted: 06/25/2020] [Indexed: 01/01/2023] Open
Abstract
Microbial reduction of selenite [Se(IV)] and tellurite [Te(IV)] to Se(0) and Te(0) can function as a detoxification mechanism and serve in energy conservation. In this study, Bacillus sp. Y3 was isolated and demonstrated to have an ability of simultaneous reduction of Se(IV) and Te(IV) during aerobic cultivation, with reduction efficiencies of 100% and 90%, respectively. Proteomics analysis revealed that the putative thioredoxin disulfide reductase (TrxR) and sulfate and energy metabolic pathway proteins were significantly upregulated after the addition of Se(IV) and Te(IV). qRT-PCR also showed an increased trxR transcription level in the presence of Se(IV) and Te(IV). Compared with a wild-type Escherichia coli strain, the TrxR-overexpressed E. coli strain showed higher Se(IV) and Te(IV) resistance levels and reduction efficiencies. Additionally, the TrxR showed in vitro Se(IV) and Te(IV) reduction activities when NADPH or NADH were present. When NADPH was used as the electron donor, the optimum conditions for enzyme activities were pH 8.0 and 37°C. The Km values of Te(IV) and Se(IV) were 16.31 and 2.91 mM, and the Vmax values of Te(IV) and Se(IV) were 12.23 and 11.20 µM min-1 mg-1, respectively. The discovery of the new reductive enzyme TrxR enriches the repertoire of the bacterial Se(IV) and Te(IV) resistance and reduction mechanisms. Bacillus sp. Y3 can efficiently reduce Se(IV) and Te(IV) simultaneously. Strain Y3 provides potential applications for selenite and tellurite bioremediation. The TrxR enzyme shows high catalytic activity for reducing Se(IV) and Te(IV). The discovery of TrxR enriches the bacterial Se(IV) and Te(IV) reduction mechanisms.
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Affiliation(s)
- Muhammad Yasir
- State Key Laboratory of Agricultural Microbiology.,College of Life Science and Technology, Huazhong Agricultural University, Wuhan, 430070, P. R. China
| | - Yuxiao Zhang
- State Key Laboratory of Agricultural Microbiology.,College of Life Science and Technology, Huazhong Agricultural University, Wuhan, 430070, P. R. China
| | - Zixiao Xu
- State Key Laboratory of Agricultural Microbiology.,College of Life Science and Technology, Huazhong Agricultural University, Wuhan, 430070, P. R. China
| | - Meizhong Luo
- College of Life Science and Technology, Huazhong Agricultural University, Wuhan, 430070, P. R. China
| | - Gejiao Wang
- State Key Laboratory of Agricultural Microbiology.,College of Life Science and Technology, Huazhong Agricultural University, Wuhan, 430070, P. R. China
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11
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Arsenate-Induced Changes in Bacterial Metabolite and Lipid Pools during Phosphate Stress. Appl Environ Microbiol 2021; 87:AEM.02261-20. [PMID: 33361371 DOI: 10.1128/aem.02261-20] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2020] [Accepted: 12/06/2020] [Indexed: 11/20/2022] Open
Abstract
Agrobacterium tumefaciens GW4 is a heterotrophic arsenite-oxidizing bacterium with a high resistance to arsenic toxicity. It is now a model organism for studying the processes of arsenic detoxification and utilization. Previously, we demonstrated that under low-phosphate conditions, arsenate [As(V)] could enhance bacterial growth and be incorporated into biomolecules, including lipids. While the basic microbial As(V) resistance mechanisms have been characterized, global metabolic responses under low phosphate remain largely unknown. In the present work, the impacts of As(V) and low phosphate on intracellular metabolite and lipid profiles of GW4 were quantified using liquid chromatography-mass spectroscopy (LC-MS) in combination with transcriptional assays and the analysis of intracellular ATP and NADH levels. Metabolite profiling revealed that oxidative stress response pathways were altered and suggested an increase in DNA repair. Changes in metabolite levels in the tricarboxylic acid (TCA) cycle along with increased ATP are consistent with As(V)-enhanced growth of A. tumefaciens GW4. Lipidomics analysis revealed that most glycerophospholipids decreased in abundance when As(V) was available. However, several glycerolipid classes increased, an outcome that is consistent with maximizing growth via a phosphate-sparing phenotype. Differentially regulated lipids included phosphotidylcholine and lysophospholipids, which have not been previously reported in A. tumefaciens The metabolites and lipids identified in this study deepen our understanding of the interplay between phosphate and arsenate on chemical and metabolic levels.IMPORTANCE Arsenic is widespread in the environment and is one of the most ubiquitous environmental pollutants. Parodoxically, the growth of certain bacteria is enhanced by arsenic when phosphate is limited. Arsenate and phosphate are chemically similar, and this behavior is believed to represent a phosphate-sparing phenotype in which arsenate is used in place of phosphate in certain biomolecules. The research presented here uses a global approach to track metabolic changes in an environmentally relevant bacterium during exposure to arsenate when phosphate is low. Our findings are relevant for understanding the environmental fate of arsenic as well as how human-associated microbiomes respond to this common toxin.
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An L, Luo X, Wu M, Feng L, Shi K, Wang G, Rosen BP, Li M. Comamonas testosteroni antA encodes an antimonite-translocating P-type ATPase. THE SCIENCE OF THE TOTAL ENVIRONMENT 2021; 754:142393. [PMID: 33254899 PMCID: PMC7885177 DOI: 10.1016/j.scitotenv.2020.142393] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/02/2020] [Revised: 09/11/2020] [Accepted: 09/13/2020] [Indexed: 05/31/2023]
Abstract
Antimony, like arsenic, is a toxic metalloid widely distributed in the environment. Microbial detoxification of antimony has recently been identified. Here we describe a novel bacterial P1B-type antimonite (Sb(III))-translocating ATPase from the antimony-mining bacterium Comamonas testosterone JL40 that confers resistance to Sb(III). In a comparative proteomics analysis of strain JL40, an operon (ant operon) was up-regulated by Sb(III). The ant operon includes three genes, antR, antC and antA. AntR belongs to the ArsR/SmtB family of metalloregulatory proteins that regulates expression of the ant operon. AntA belongs to the P1B family of the P-type cation-translocating ATPases. It has both similarities to and differences from other members of the P1B-1 subfamily and appears to be the first identified member of a distinct subfamily that we designate P1B-8. Expression AntA in E. coli AW3110 (Δars) conferred resistance to Sb(III) and reduced the intracellular concentration of Sb(III) but not As(III) or other metals. Everted membrane vesicles from cells expressing antA accumulated Sb(III) but not As(III), where uptake in everted vesicles reflects efflux from cells. AntC is a small protein with a potential Sb(III) binding site, and co-expression of AntC with AntA increased resistance to Sb(III). We propose that AntC functions as an Sb(III) chaperone to AntA, augmenting Sb(III) efflux. The identification of a novel Sb(III)-translocating ATPase enhances our understanding of the biogeochemical cycling of environmental antimony by bacteria.
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Affiliation(s)
- Lijin An
- State Key Laboratory of Agricultural Microbiology, College of Life Science and Technology, Huazhong Agricultural University, Wuhan, Hubei 430070, PR China
| | - Xiong Luo
- State Key Laboratory of Agricultural Microbiology, College of Life Science and Technology, Huazhong Agricultural University, Wuhan, Hubei 430070, PR China
| | - Minghan Wu
- State Key Laboratory of Agricultural Microbiology, College of Life Science and Technology, Huazhong Agricultural University, Wuhan, Hubei 430070, PR China
| | - Liling Feng
- State Key Laboratory of Agricultural Microbiology, College of Life Science and Technology, Huazhong Agricultural University, Wuhan, Hubei 430070, PR China
| | - Kaixiang Shi
- State Key Laboratory of Agricultural Microbiology, College of Life Science and Technology, Huazhong Agricultural University, Wuhan, Hubei 430070, PR China
| | - Gejiao Wang
- State Key Laboratory of Agricultural Microbiology, College of Life Science and Technology, Huazhong Agricultural University, Wuhan, Hubei 430070, PR China
| | - Barry P Rosen
- Department of Cellular Biology and Pharmacology, Herbert Wertheim College of Medicine, Florida International University, Miami, FL 33199, United States
| | - Mingshun Li
- State Key Laboratory of Agricultural Microbiology, College of Life Science and Technology, Huazhong Agricultural University, Wuhan, Hubei 430070, PR China.
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Shi K, Dai X, Fan X, Zhang Y, Chen Z, Wang G. Simultaneous removal of chromate and arsenite by the immobilized Enterobacter bacterium in combination with chemical reagents. CHEMOSPHERE 2020; 259:127428. [PMID: 34883557 DOI: 10.1016/j.chemosphere.2020.127428] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/07/2019] [Revised: 05/02/2020] [Accepted: 06/14/2020] [Indexed: 06/13/2023]
Abstract
Simultaneous chromate [Cr(VI)] reduction and arsenite [As(III)] oxidation is a promising pretreatment process for Cr and As removal. Here, a facultative anaerobic bacterium, Enterobacter sp. Z1, presented capacities of simultaneous Cr(VI) reduction and As(III) oxidation during anoxic cultivation in a wild range of temperature (20-45 °C) and pH (Cerkez et al., 2015; Chen et al., 2015; China Environmental Prote, 1996; Fan et al., 2008, 2019) conditions. Strikingly, strain Z1 could simultaneously contribute up to 92.8% of the reduction of Cr(VI) and 45.8% of the oxidation of As(III) in wastewater. The cells of strain Z1 were embedded with sodium alginate to produce biobeads, and the biobeads exhibited stable ratio of Cr(VI) reduction (91.8%) and As(III) oxidation (29.6%) even in the 5 continuous cycles of wastewater treatment. Moreover, in a process pretreated with the Z1 biobeads followed a precipitation with Ca(OH)2 and FeCl3, the removal efficiencies in wastewater were 98.9% and 98.3% for total Cr and As, respectively, which were 44.1% and 9.8% higher than those of using Ca(OH)2 and FeCl3, only. The residual amounts of Cr and As met the national standard levels of wastewater discharge. Proteomics analysis showed that cysteine, sulfur and methionine metabolisms, As resistance and oxidoreductase (CysH, CysI, CysJ, NemA and HemF) were induced by Cr(VI) and As(III). Moreover, the addition of cysteine to the medium also significantly improved bacterial Cr(VI) reduction rate. Our results provide a novel microbial pretreatment approach for enhancing remediation of Cr(VI) and As(III) pollution in wastewater, and reveal the evident that cysteine, sulfur and methionine metabolisms, As resistance and oxidoreductases are associated with the redox conversion of Cr(VI) and As(III).
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Affiliation(s)
- Kaixiang Shi
- State Key Laboratory of Agricultural Microbiology, College of Life Science and Technology, Huazhong Agricultural University, Wuhan, 430070, PR China
| | - Xingli Dai
- State Key Laboratory of Agricultural Microbiology, College of Life Science and Technology, Huazhong Agricultural University, Wuhan, 430070, PR China
| | - Xia Fan
- State Key Laboratory of Agricultural Microbiology, College of Life Science and Technology, Huazhong Agricultural University, Wuhan, 430070, PR China
| | - Yuxiao Zhang
- State Key Laboratory of Agricultural Microbiology, College of Life Science and Technology, Huazhong Agricultural University, Wuhan, 430070, PR China
| | - Zhengjun Chen
- State Key Laboratory of Agricultural Microbiology, College of Life Science and Technology, Huazhong Agricultural University, Wuhan, 430070, PR China
| | - Gejiao Wang
- State Key Laboratory of Agricultural Microbiology, College of Life Science and Technology, Huazhong Agricultural University, Wuhan, 430070, PR China.
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Shi K, Wang Q, Wang G. Microbial Oxidation of Arsenite: Regulation, Chemotaxis, Phosphate Metabolism and Energy Generation. Front Microbiol 2020; 11:569282. [PMID: 33072028 PMCID: PMC7533571 DOI: 10.3389/fmicb.2020.569282] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2020] [Accepted: 08/21/2020] [Indexed: 12/11/2022] Open
Abstract
Arsenic (As) is a metalloid that occurs widely in the environment. The biological oxidation of arsenite [As(III)] to arsenate [As(V)] is considered a strategy to reduce arsenic toxicity and provide energy. In recent years, research interests in microbial As(III) oxidation have been growing, and related new achievements have been revealed. This review focuses on the highlighting of the novel regulatory mechanisms of bacterial As(III) oxidation, the physiological relevance of different arsenic sensing systems and functional relationship between microbial As(III) oxidation and those of chemotaxis, phosphate uptake, carbon metabolism and energy generation. The implication to environmental bioremediation applications of As(III)-oxidizing strains, the knowledge gaps and perspectives are also discussed.
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Affiliation(s)
- Kaixiang Shi
- State Key Laboratory of Agricultural Microbiology, College of Life Science and Technology, Huazhong Agricultural University, Wuhan, China
| | - Qian Wang
- Department of Microbiology and Immunology, Montana State University, Bozeman, MT, United States
| | - Gejiao Wang
- State Key Laboratory of Agricultural Microbiology, College of Life Science and Technology, Huazhong Agricultural University, Wuhan, China
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Cheng L, Min D, Liu DF, Li WW, Yu HQ. Sensing and Approaching Toxic Arsenate by Shewanella putrefaciens CN-32. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2019; 53:14604-14611. [PMID: 31747260 DOI: 10.1021/acs.est.9b05890] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Although arsenic at a high concentration imposes strong selective pressure on microbes, various microbes have been found to grow in As-rich environments. So far, little is known about how microbes can sense and move toward arsenate in the environment, and the underlying molecular mechanisms have not been revealed. Here, we report the chemotaxis response toward arsenate (As(V)) by Shewanella putrefaciens CN-32, a model dissimilatory metal-reducing bacterium (DMRB), and elucidate the mechanisms. We find that S. putrefaciens CN-32 exhibits a chemotactic behavior toward As(V) and diverse electron acceptors. To sense As(V), S. putrefaciens CN-32 requires functional arsenate respiratory reductase but does not depend on its metal-reducing-like respiratory pathway. We observe that such a sense is governed by an energy taxis mechanism and mediated by several methyl-accepting chemotaxis proteins (MCPs), rather than a specific MCP. Moreover, we reveal that the chemotactic signal transduction pathway is conserved in Shewanella, and histidine kinase and flagella-mediated motility are essential for taxis toward As(V). This work reverses the conventional view about arsenic as a chemotactic inhibitor to microbes by revealing the positive chemotaxis of Shewanella to As(V).
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Zhang Y, Xu Z, Li J, Liu D, Yuan Y, Chen Z, Wang G. Cooperation between two strains of Enterobacter and Klebsiella in the simultaneous nitrogen removal and phosphate accumulation processes. BIORESOURCE TECHNOLOGY 2019; 291:121854. [PMID: 31357041 DOI: 10.1016/j.biortech.2019.121854] [Citation(s) in RCA: 30] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/16/2019] [Revised: 07/18/2019] [Accepted: 07/20/2019] [Indexed: 06/10/2023]
Abstract
Two strains, Enterobacter sp. Z1 and Klebsiella sp. Z2, were exhibited great capacities for heterotrophic nitrification-aerobic denitrification (HNAD) and intracellular phosphate accumulation. Strikingly, the co-cultured strains enhanced the removal efficiency of total nitrogen and phosphate, with removal efficiencies of ammonia, nitrate, nitrite and soluble phosphate of 99.64%, 99.85%, 96.94% and 66.7% respectively. Furthermore, high removal efficiencies from wastewaters with high concentrations of ammonia (over 1000 mg/L) were achieved by inoculation with the co-strains, which left residual ammonia of less than 1 mg/L within 10 h. To elucidate the mechanism of HNAD in co-strains, quantitative PCR was carried out to examine the expression levels of hydroxylamine oxidase (Hao), nitrate reductase (NapA and NarG), nitrite reductase (NirS) and polyphosphate kinase (Ppk), and the results showed that the napA2, narG and ppk genes in the strains were significantly upregulated under the co-cultured conditions and provided an explanation for the nitrogen and phosphate removal.
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Affiliation(s)
- Yuxiao Zhang
- State Key Laboratory of Agricultural Microbiology, College of Life Science and Technology, Huazhong Agricultural University, Wuhan 430070, PR China
| | - Zixiao Xu
- State Key Laboratory of Agricultural Microbiology, College of Life Science and Technology, Huazhong Agricultural University, Wuhan 430070, PR China
| | - Jingxin Li
- State Key Laboratory of Agricultural Microbiology, College of Life Science and Technology, Huazhong Agricultural University, Wuhan 430070, PR China
| | - Deli Liu
- College of Life Science, Huazhong Agricultural University, Wuhan 430070, PR China
| | - Yongze Yuan
- College of Life Science, Huazhong Agricultural University, Wuhan 430070, PR China
| | - Zhengjun Chen
- State Key Laboratory of Agricultural Microbiology, College of Life Science and Technology, Huazhong Agricultural University, Wuhan 430070, PR China
| | - Gejiao Wang
- State Key Laboratory of Agricultural Microbiology, College of Life Science and Technology, Huazhong Agricultural University, Wuhan 430070, PR China.
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Efflux proteins MacAB confer resistance to arsenite and penicillin/macrolide-type antibiotics in Agrobacterium tumefaciens 5A. World J Microbiol Biotechnol 2019; 35:115. [PMID: 31332542 DOI: 10.1007/s11274-019-2689-7] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2019] [Accepted: 07/07/2019] [Indexed: 10/26/2022]
Abstract
Antibiotic and arsenic (As) contaminations are worldwide public health problems. Previously, the bacterial ABC-type efflux protein MacAB reportedly conferred resistance to macrolide-type antibiotics but not to other metal(loid)s. In this study, the roles of MacAB for the co-resistance of different antibiotics and several metal(loid)s were analyzed in Agrobacterium tumefaciens 5A, a strain resistant to arsenite [As(III)] and several types of antibiotics. The macA and macB genes were cotranscribed, and macB was deleted in A. tumefaciens 5A and heterologously expressed in Escherichia coli AW3110 and E. coli S17-1. Compared to the wild-type strain 5A, the macB deletion strain reduced bacterial resistance levels to several macrolide-type and penicillin-type antibiotics but not to cephalosporin-type antibiotics. In addition, the macB deletion strain showed lower resistance to As(III) but not to arsenate [As(V)], antimonite [Sb(III)] and cadmium chloride [Cd(II)]. The mutant strain 5A-ΔmacB cells accumulated more As(III) than the cells of the wild-type. Furthermore, heterologous expression of MacAB in E. coli S17-1 showed that MacAB was essential for resistance to macrolide, several penicillin-type antibiotics and As(III) but not to As(V). Heterologous expression of MacAB in E. coli AW3110 reduced the cellular accumulation of As(III) but not of As(V), indicating that MacAB is responsible for the efflux of As(III). These results demonstrated that, in addition to macrolide-type antibiotics, MacAB also conferred resistance to penicillin-type antibiotics and As(III) by extruding them out of cells. This finding contributes to a better understanding of the bacterial resistance mechanisms of antibiotics and metal(loid)s.
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Qiao Z, Huang J, Cao Y, Shi K, Wang G. Genetics and proteomics analyses reveal the roles of PhoB1 and PhoB2 regulators in bacterial responses to arsenite and phosphate. Res Microbiol 2019; 170:263-271. [PMID: 31279088 DOI: 10.1016/j.resmic.2019.06.006] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2019] [Revised: 06/18/2019] [Accepted: 06/21/2019] [Indexed: 11/25/2022]
Abstract
In bacteria, phosphate (Pi) stress response is governed by the two-component regulatory system, sensor kinase PhoR and its cognate response regulatory protein PhoB. The arsenite [As(III)]-oxidizing bacterium Agrobacterium tumefaciens GW4 contains two phoB genes, phoB1 and phoB2. phoB1 is adjacent to As(III)-oxidizing genes, however, the functions of PhoB1 and PhoB2 remain unclear. Here, phoB1 and phoB2 were each deleted in-frame, and proteomics, qRT-PCR and protein-DNA interaction were performed. We found that (1) phoB1 and phoB2 were both upregulated under low Pi conditions and phoB1 was induced by As(III), but phoB2 was not; (2) deletion of phoB1 reduced As(III)-oxidizing efficiency and protein-DNA interaction analysis showed PhoB1 could interact with aioXSR promoter to regulate As(III) oxidation; (3) deletions of phoB1 or phoB2 both reduced exopolysaccharides (EPS) synthesis; and (4) PhoB1 influenced Pi uptake, As(III) oxidation, EPS synthesis, TCA cycle, energy production and stress response with As(III), and PhoB2 was associated with Pi uptake and EPS synthesis in low Pi conditions. These results showed PhoB1 and PhoB2 were both involved in Pi acquisition, PhoB1 was more important with As(III) and PhoB2 played a major role without As(III). Strain GW4 uses these two regulators to survive under low Pi and arsenic-rich environments.
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Affiliation(s)
- Zixu Qiao
- State Key Laboratory of Agricultural Microbiology, College of Life Science and Technology, Huazhong Agricultural University, Wuhan, 430070, PR China.
| | - Jing Huang
- State Key Laboratory of Agricultural Microbiology, College of Life Science and Technology, Huazhong Agricultural University, Wuhan, 430070, PR China.
| | - Yajing Cao
- State Key Laboratory of Agricultural Microbiology, College of Life Science and Technology, Huazhong Agricultural University, Wuhan, 430070, PR China.
| | - Kaixiang Shi
- State Key Laboratory of Agricultural Microbiology, College of Life Science and Technology, Huazhong Agricultural University, Wuhan, 430070, PR China.
| | - Gejiao Wang
- State Key Laboratory of Agricultural Microbiology, College of Life Science and Technology, Huazhong Agricultural University, Wuhan, 430070, PR China.
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Martín-Mora D, Ortega Á, Matilla MA, Martínez-Rodríguez S, Gavira JA, Krell T. The Molecular Mechanism of Nitrate Chemotaxis via Direct Ligand Binding to the PilJ Domain of McpN. mBio 2019; 10:e02334-18. [PMID: 30782655 PMCID: PMC6381276 DOI: 10.1128/mbio.02334-18] [Citation(s) in RCA: 27] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2018] [Accepted: 01/07/2019] [Indexed: 12/21/2022] Open
Abstract
Chemotaxis and energy taxis permit directed bacterial movements in gradients of environmental cues. Nitrate is a final electron acceptor for anaerobic respiration and can also serve as a nitrogen source for aerobic growth. Previous studies indicated that bacterial nitrate taxis is mediated by energy taxis mechanisms, which are based on the cytosolic detection of consequences of nitrate metabolism. Here we show that Pseudomonas aeruginosa PAO1 mediates nitrate chemotaxis on the basis of specific nitrate sensing by the periplasmic PilJ domain of the PA2788/McpN chemoreceptor. The presence of nitrate reduced mcpN transcript levels, and McpN-mediated taxis occurred only under nitrate starvation conditions. In contrast to the NarX and NarQ sensor kinases, McpN bound nitrate specifically and showed no affinity for other ligands such as nitrite. We report the three-dimensional structure of the McpN ligand binding domain (LBD) at 1.3-Å resolution in complex with nitrate. Although structurally similar to 4-helix bundle domains, the ligand binding mode differs since a single nitrate molecule is bound to a site on the dimer symmetry axis. As for 4-helix bundle domains, ligand binding stabilized the McpN-LBD dimer. McpN homologues showed a wide phylogenetic distribution, indicating that nitrate chemotaxis is a widespread phenotype. These homologues were particularly abundant in bacteria that couple sulfide/sulfur oxidation with nitrate reduction. This work expands the range of known chemotaxis effectors and forms the basis for the exploration of nitrate chemotaxis in other bacteria and for the study of its physiological role.IMPORTANCE Nitrate is of central importance in bacterial physiology. Previous studies indicated that movements toward nitrate are due to energy taxis, which is based on the cytosolic sensing of consequences of nitrate metabolism. Here we present the first report on nitrate chemotaxis. This process is initiated by specific nitrate binding to the periplasmic ligand binding domain (LBD) of McpN. Nitrate chemotaxis is highly regulated and occurred only under nitrate starvation conditions, which is helpful information to explore nitrate chemotaxis in other bacteria. We present the three-dimensional structure of the McpN-LBD in complex with nitrate, which is the first structure of a chemoreceptor PilJ-type domain. This structure reveals striking similarities to that of the abundant 4-helix bundle domain but employs a different sensing mechanism. Since McpN homologues show a wide phylogenetic distribution, nitrate chemotaxis is likely a widespread phenomenon with importance for the life cycle of ecologically diverse bacteria.
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Affiliation(s)
- David Martín-Mora
- Estación Experimental del Zaidín, Department of Environmental Protection, Consejo Superior de Investigaciones Científicas, Granada, Spain
| | - Álvaro Ortega
- Estación Experimental del Zaidín, Department of Environmental Protection, Consejo Superior de Investigaciones Científicas, Granada, Spain
| | - Miguel A Matilla
- Estación Experimental del Zaidín, Department of Environmental Protection, Consejo Superior de Investigaciones Científicas, Granada, Spain
| | - Sergio Martínez-Rodríguez
- Departamento de Bioquímica y Biología Molecular III e Inmunología, Universidad de Granada, Melilla, Spain
- Laboratorio de Estudios Cristalográficos, IACT, Superior de Investigaciones Científicas (CSIC) y la Universidad de Granada (UGR), Armilla, Spain
| | - José A Gavira
- Laboratorio de Estudios Cristalográficos, IACT, Superior de Investigaciones Científicas (CSIC) y la Universidad de Granada (UGR), Armilla, Spain
| | - Tino Krell
- Estación Experimental del Zaidín, Department of Environmental Protection, Consejo Superior de Investigaciones Científicas, Granada, Spain
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Agrobacterium-mediated horizontal gene transfer: Mechanism, biotechnological application, potential risk and forestalling strategy. Biotechnol Adv 2018; 37:259-270. [PMID: 30579929 DOI: 10.1016/j.biotechadv.2018.12.008] [Citation(s) in RCA: 41] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2018] [Revised: 12/18/2018] [Accepted: 12/18/2018] [Indexed: 11/20/2022]
Abstract
The extraordinary capacity of Agrobacterium to transfer its genetic material to host cell makes it evolve from phytopathogen to a powerful transgenic vector. Agrobacterium-mediated stable transformation is widely used as the preferred method to create transgenic plants for molecular plant biology research and crop breeding. Recent years, both mechanism and application of Agrobacterium-mediated horizontal gene transfer have made significant progresses, especially Agrobacterium-mediated transient transformation was developed for plant biotechnology industry to produce recombinant proteins. Agrobacterium strains are almost used and saved not only by each of microbiology and molecular plant labs, but also by many of plant biotechnology manufacturers. Agrobacterium is able to transfer its genetic material to a broad range of hosts, including plant and non-plant hosts. As a consequence, the concern of environmental risk associated with the accidental release of genetically modified Agrobacterium arises. In this article, we outline the recent progress in the molecular mechanism of Agrobacterium-meditated gene transfer, focus on the application of Agrobacterium-mediated horizontal gene transfer, and review the potential risk associated with Agrobacterium-meditated gene transfer. Based on the comparison between the infecting process of Agrobacterium as a pathogen and the transgenic process of Agrobacterium as a transgenic vector, we realize that chemotaxis is the distinct difference between these two biological processes and thus discuss the possible role of chemotaxis in forestalling the potential risk of Agrobacterium-meditated horizontal gene transfer to non-target plant species.
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Efflux Transporter ArsK Is Responsible for Bacterial Resistance to Arsenite, Antimonite, Trivalent Roxarsone, and Methylarsenite. Appl Environ Microbiol 2018; 84:AEM.01842-18. [PMID: 30315082 DOI: 10.1128/aem.01842-18] [Citation(s) in RCA: 47] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2018] [Accepted: 10/09/2018] [Indexed: 11/20/2022] Open
Abstract
Arsenic-resistant bacteria have evolved various efflux systems for arsenic resistance. Five arsenic efflux proteins, ArsB, Acr3, ArsP, ArsJ, and MSF1, have been reported. In this study, comprehensive analyses were performed to study the function of a putative major facilitator superfamily gene, arsK, and the regulation of arsK transcriptional expression in Agrobacterium tumefaciens GW4. We found that (i) arsK is located on an arsenic gene island in strain GW4. ArsK orthologs are widely distributed in arsenic-resistant bacteria and are phylogenetically divergent from the five reported arsenic efflux proteins, indicating that it may be a novel arsenic efflux transporter. (ii) Reporter gene assays showed that the expression of arsK was induced by arsenite [As(III)], antimonite [Sb(III)], trivalent roxarsone [Rox(III)], methylarsenite [MAs(III)], and arsenate [As(V)]. (iii) Heterologous expression of ArsK in an arsenic-hypersensitive Escherichia coli strain showed that ArsK was essential for resistance to As(III), Sb(III), Rox(III), and MAs(III) but not to As(V), dimethylarsenite [dimethyl-As(III)], or Cd(II). (iv) ArsK reduced the cellular accumulation of As(III), Sb(III), Rox(III), and MAs(III) but not to As(V) or dimethyl-As(III). (v) A putative arsenic regulator gene arsR2 was cotranscribed with arsK, and (vi) ArsR2 interacted with the arsR2-arsK promoter region without metalloids and was derepressed by As(III), Sb(III), Rox(III), and MAs(III), indicating the repression activity of ArsR2 for the transcription of arsK These results demonstrate that ArsK is a novel arsenic efflux protein for As(III), Sb(III), Rox(III), and MAs(III) and is regulated by ArsR2. Bacteria use the arsR2-arsK operon for resistance to several trivalent arsenicals or antimonials.IMPORTANCE The metalloid extrusion systems are very important bacterial resistance mechanisms. Each of the previously reported ArsB, Acr3, ArsP, ArsJ, and MSF1 transport proteins conferred only inorganic or organic arsenic/antimony resistance. In contrast, ArsK confers resistance to several inorganic and organic trivalent arsenicals and antimonials. The identification of the novel efflux transporter ArsK enriches our understanding of bacterial resistance to trivalent arsenite [As(III)], antimonite [Sb(III)], trivalent roxarsone [Rox(III)], and methylarsenite [MAs(III)].
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Xia X, Wu S, Li L, Xu B, Wang G. The Cytochrome bd Complex Is Essential for Chromate and Sulfide Resistance and Is Regulated by a GbsR-Type Regulator, CydE, in Alishewanella Sp. WH16-1. Front Microbiol 2018; 9:1849. [PMID: 30147685 PMCID: PMC6096048 DOI: 10.3389/fmicb.2018.01849] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2017] [Accepted: 07/24/2018] [Indexed: 01/17/2023] Open
Abstract
Sulfate-reducing bacteria are a group of microorganisms that use sulfate as an electron acceptor. These bacteria are useful in the bioremediation of heavy metal pollution since they can reduce/precipitate metals. Previously, we identified the Alishewanella strain WH16-1 from soil of a copper and iron mine and determined that it can reduce sulfate and chromate and that it was tolerant to many heavy metals. In this study, we investigated the chromate reduction mechanism of strain WH16-1 through Tn5 transposon mutagenesis. A cytochrome bd (cytbd) Tn5 mutant was generated (Δcytbd), and a detail analysis showed that the following: (1) gene cydE (coding for a GbsR-type regulator) was co-transcribed with the two subunits coding genes of the Cytochrome bd complex (Cytbd), namely, cydA and cydB, based on RT-PCR analysis, and similar gene arrangements were also found in other Alteromonadaceae family strains; (2) the chromate resistance level was dramatically decreased and chromate reduction efficiency also decreased in strain Δcytbd compared to the wild-type and a complemented strain (Δcytbd-C); (3) Cytbd could catalyze the decomposition of H2O2 according to the analyses of H2O2 decomposition ability, cellular H2O2 contents, H2O2 inhibition zone, and H2O2 sensitivity tests; (4) surprisingly, chromate was not an inducer of the expression of Cytbd, but sulfate induced expression of Cytbd, and sulfate/sulfide resistance levels were also decreased in the Δcytbd strain; (5) the addition of sulfate enhanced the chromate resistance level and reduction efficiency; (6) Cytbd expression was repressed by CydE and derepressed by sulfate based on an in vivo bacterial one hybrid system and in vitro EMSA tests; and (7) DNA footprinting and short-fragment EMSA tests revealed two binding sites of CydE in its promoter region. All these results showed that Cytbd is negatively regulated by CydE and derepressed by sulfate. In addition, Cytbd contributes to the resistance of sulfate and sulfide, and sulfide could be used as a reductant to reduce chromate. Moreover, Cytbd is essential to decompose H2O2 to decrease cellular oxidative stress. Thus, the regulation and function of Cytbd may explain why sulfate could enhance chromate reduction.
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Affiliation(s)
- Xian Xia
- State Key Laboratory of Agricultural Microbiology, College of Life Sciences and Technology, Huazhong Agricultural University, Wuhan, China
| | - Shijuan Wu
- State Key Laboratory of Agricultural Microbiology, College of Life Sciences and Technology, Huazhong Agricultural University, Wuhan, China
| | - Liqiong Li
- State Key Laboratory of Agricultural Microbiology, College of Life Sciences and Technology, Huazhong Agricultural University, Wuhan, China
| | - Biao Xu
- State Key Laboratory of Agricultural Microbiology, College of Life Sciences and Technology, Huazhong Agricultural University, Wuhan, China
| | - Gejiao Wang
- State Key Laboratory of Agricultural Microbiology, College of Life Sciences and Technology, Huazhong Agricultural University, Wuhan, China
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Shi K, Wang Q, Fan X, Wang G. Proteomics and genetic analyses reveal the effects of arsenite oxidation on metabolic pathways and the roles of AioR in Agrobacterium tumefaciens GW4. ENVIRONMENTAL POLLUTION (BARKING, ESSEX : 1987) 2018; 235:700-709. [PMID: 29339339 DOI: 10.1016/j.envpol.2018.01.006] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/27/2017] [Revised: 01/02/2018] [Accepted: 01/02/2018] [Indexed: 06/07/2023]
Abstract
A heterotrophic arsenite [As(III)]-oxidizing bacterium Agrobacterium tumefaciens GW4 isolated from As(III)-rich groundwater sediment showed high As(III) resistance and could oxidize As(III) to As(V). The As(III) oxidation could generate energy and enhance growth, and AioR was the regulator for As(III) oxidase. To determine the related metabolic pathways mediated by As(III) oxidation and whether AioR regulated other cellular responses to As(III), isobaric tags for relative and absolute quantitation (iTRAQ) was performed in four treatments, GW4 (+AsIII)/GW4 (-AsIII), GW4-ΔaioR (+AsIII)/GW4-ΔaioR (-AsIII), GW4-ΔaioR (-AsIII)/GW4 (-AsIII) and GW4-ΔaioR (+AsIII)/GW4 (+AsIII). A total of 41, 71, 82 and 168 differentially expressed proteins were identified, respectively. Using electrophoretic mobility shift assay (EMSA) and qRT-PCR, 12 genes/operons were found to interact with AioR. These results indicate that As(III) oxidation alters several cellular processes related to arsenite, such as As resistance (ars operon), phosphate (Pi) metabolism (pst/pho system), TCA cycle, cell wall/membrane, amino acid metabolism and motility/chemotaxis. In the wild type with As(III), TCA cycle flow is perturbed, and As(III) oxidation and fermentation are the main energy resources. However, when strain GW4-ΔaioR lost the ability of As(III) oxidation, the TCA cycle is the main way to generate energy. A regulatory cellular network controlled by AioR is constructed and shows that AioR is the main regulator for As(III) oxidation, besides, several other functions related to As(III) are regulated by AioR in parallel.
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Affiliation(s)
- Kaixiang Shi
- State Key Laboratory of Agricultural Microbiology, College of Life Science and Technology, Huazhong Agricultural University, Wuhan, 430070, PR China
| | - Qian Wang
- State Key Laboratory of Agricultural Microbiology, College of Life Science and Technology, Huazhong Agricultural University, Wuhan, 430070, PR China
| | - Xia Fan
- State Key Laboratory of Agricultural Microbiology, College of Life Science and Technology, Huazhong Agricultural University, Wuhan, 430070, PR China
| | - Gejiao Wang
- State Key Laboratory of Agricultural Microbiology, College of Life Science and Technology, Huazhong Agricultural University, Wuhan, 430070, PR China.
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24
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Zhuang W, Liu H, Li J, Chen L, Wang G. Regulation of Class A β-Lactamase CzoA by CzoR and IscR in Comamonas testosteroni S44. Front Microbiol 2017; 8:2573. [PMID: 29312251 PMCID: PMC5744064 DOI: 10.3389/fmicb.2017.02573] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2017] [Accepted: 12/11/2017] [Indexed: 11/13/2022] Open
Abstract
A genomic analysis of Comamonas testosteroni S44 revealed a gene that encodes a LysR family transcriptional regulator (here named czoR, czo for cefazolin) located upstream of a putative class A β-lactamase encoding gene (here named czoA). A putative DNA-binding motif of the Fe-S cluster assembly regulator IscR was identified in the czoR-czoA intergenic region. Real-time RT-PCR and lacZ fusion expression assays indicated that transcription of czoA and czoR were induced by multiple β-lactams. CzoA expressed in Escherichia coli was shown to contribute to susceptibility to a wide range of β-lactams judged from minimum inhibitory concentrations. In vitro enzymatic assays showed that CzoA hydrolyzed seven β-lactams, including benzylpenicillin, ampicillin, cefalexin, cefazolin, cefuroxime, ceftriaxone, and cefepime. Deletion of either iscR or czoR increased susceptibility to cefalexin and cefazolin, while complemented strains restored their wild-type susceptibility levels. Electrophoretic mobility shift assays (EMSA) demonstrated that CzoR and IscR bind to different sites of the czoR-czoA intergenic region. Precise CzoR- and IscR-binding sites were confirmed via DNase I footprinting or short fragment EMSA. When cefalexin or cefazolin was added to cultures, czoR deletion completely inhibited czoA expression but did not affect iscR transcription, while iscR deletion decreased the expressions of both czoR and czoA. These results reveal that CzoR positively affects the expression of czoA with its own expression upregulated by IscR.
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Affiliation(s)
- Weiping Zhuang
- State Key Laboratory of Agricultural Microbiology, College of Life Science and Technology, Huazhong Agricultural University, Wuhan, China
| | - Hongliang Liu
- Shandong Provincial Research Center for Bioinformatic Engineering and Technique, School of Life Sciences, Shandong University of Technology, Zibo, China
| | - Jingxin Li
- State Key Laboratory of Agricultural Microbiology, College of Life Science and Technology, Huazhong Agricultural University, Wuhan, China
| | - Lu Chen
- State Key Laboratory of Agricultural Microbiology, College of Life Science and Technology, Huazhong Agricultural University, Wuhan, China
| | - Gejiao Wang
- State Key Laboratory of Agricultural Microbiology, College of Life Science and Technology, Huazhong Agricultural University, Wuhan, China
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25
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Corsini PM, Walker KT, Santini JM. Expression of the arsenite oxidation regulatory operon in Rhizobium sp. str. NT-26 is under the control of two promoters that respond to different environmental cues. Microbiologyopen 2017; 7:e00567. [PMID: 29250936 PMCID: PMC6011840 DOI: 10.1002/mbo3.567] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2017] [Revised: 10/31/2017] [Accepted: 11/03/2017] [Indexed: 12/04/2022] Open
Abstract
Rhizobium sp. str. NT‐26 is a Gram‐negative facultative chemolithoautotrophic arsenite oxidizer that has been used as a model organism to study various aspects of arsenite oxidation including the regulation of arsenite oxidation. The three regulatory genes, aioX, aioS, and aioR, are cotranscribed when NT‐26 was grown in the presence or absence of arsenite. The aioXSR operon is upregulated in stationary phase but not by the presence of arsenite in the growth medium. The two transcription start sites upstream of aioX were determined which led to the identification of two promoters, the housekeeping promoter RpoD and the growth‐phase‐dependent promoter RpoE2. Promoter–lacZ fusions confirmed their constitutive and stationary phase expressions. The involvement of the NT‐26 sigma factor RpoE2 in acting on the NT‐26 RpoE2 promoter was confirmed in vivo in Escherichia coli, which lacks a rpoE2 homolog, using a strain carrying both the promoter–lacZ fusion and the NT‐26 rpoE2 gene. An in silico approach was used to search for other RpoE2 promoters and AioR‐binding motifs and led to the identification of other genes that could be regulated by these proteins including those involved in quorum sensing, chemotaxis, and motility expanding the signaling networks important for the microbial metabolism of arsenite.
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Affiliation(s)
- Paula M Corsini
- Institute of Structural and Molecular Biology, Division of Biosciences, University College London, London, UK
| | - Kenneth T Walker
- Institute of Structural and Molecular Biology, Division of Biosciences, University College London, London, UK
| | - Joanne M Santini
- Institute of Structural and Molecular Biology, Division of Biosciences, University College London, London, UK
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26
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Effects upon metabolic pathways and energy production by Sb(III) and As(III)/Sb(III)-oxidase gene aioA in Agrobacterium tumefaciens GW4. PLoS One 2017; 12:e0172823. [PMID: 28241045 PMCID: PMC5328403 DOI: 10.1371/journal.pone.0172823] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2016] [Accepted: 02/11/2017] [Indexed: 12/23/2022] Open
Abstract
Agrobacterium tumefaciens GW4 is a heterotrophic arsenite [As(III)]/antimonite [Sb(III)]-oxidizing strain. The As(III) oxidase AioAB is responsible for As(III) oxidation in the periplasm and it is also involved in Sb(III) oxidation in Agrobacterium tumefaciens 5A. In addition, Sb(III) oxidase AnoA and cellular H2O2 are also responsible for Sb(III) oxidation in strain GW4. However, the deletion of aioA increased the Sb(III) oxidation efficiency in strain GW4. In the present study, we found that the cell mobility to Sb(III), ATP and NADH contents and heat release were also increased by Sb(III) and more significantly in the aioA mutant. Proteomics and transcriptional analyses showed that proteins/genes involved in Sb(III) oxidation and resistance, stress responses, carbon metabolism, cell mobility, phosphonate and phosphinate metabolism, and amino acid and nucleotide metabolism were induced by Sb(III) and were more significantly induced in the aioA mutant. The results suggested that Sb(III) oxidation may produce energy. In addition, without periplasmic AioAB, more Sb(III) would enter bacterial cells, however, the cytoplasmic AnoA and the oxidative stress response proteins were significantly up-regulated, which may contribute to the increased Sb(III) oxidation efficiency. Moreover, the carbon metabolism was also activated to generate more energy against Sb(III) stress. The generated energy may be used in Sb transportation, DNA repair, amino acid synthesis, and cell mobility, and may be released in the form of heat.
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