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Latorre M, Quenti D, Travisany D, Singh KV, Murray BE, Maass A, Cambiazo V. The Role of Fur in the Transcriptional and Iron Homeostatic Response of Enterococcus faecalis. Front Microbiol 2018; 9:1580. [PMID: 30065712 PMCID: PMC6056675 DOI: 10.3389/fmicb.2018.01580] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2018] [Accepted: 06/25/2018] [Indexed: 01/23/2023] Open
Abstract
The ferric uptake regulator (Fur) plays a major role in controlling the expression of iron homeostasis genes in bacterial organisms. In this work, we fully characterized the capacity of Fur to reconfigure the global transcriptional network and influence iron homeostasis in Enterococcus faecalis. The characterization of the Fur regulon from E. faecalis indicated that this protein (Fur) regulated the expression of genes involved in iron uptake systems, conferring to the system a high level of efficiency and specificity to respond under different iron exposure conditions. An RNAseq assay coupled with a systems biology approach allowed us to identify the first global transcriptional network activated by different iron treatments (excess and limited), with and without the presence of Fur. The results showed that changes in iron availability activated a complex network of transcriptional factors in E. faecalis, among them global regulators such as LysR, ArgR, GalRS, and local regulators, LexA and CopY, which were also stimulated by copper and zinc treatments. The deletion of Fur impacted the expression of genes encoding for ABC transporters, energy production and [Fe-S] proteins, which optimized detoxification and iron uptake under iron excess and limitation, respectively. Finally, considering the close relationship between iron homeostasis and pathogenesis, our data showed that the absence of Fur increased the internal concentration of iron in the bacterium and also affected its ability to produce biofilm. These results open new alternatives in the field of infection mechanisms of E. faecalis.
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Affiliation(s)
- Mauricio Latorre
- Laboratorio de Bioinformática y Expresión Génica, Instituto de Nutrición y Tecnología de los Alimentos, Universidad de Chile, Santiago, Chile.,Mathomics, Center for Mathematical Modeling, Universidad de Chile, Santiago, Chile.,Center for Genome Regulation (Fondap 15090007), Universidad de Chile, Santiago, Chile.,Instituto de Ciencias de la Ingeniería, Universidad de O'Higgins, Rancagua, Chile
| | - Daniela Quenti
- Laboratorio de Bioinformática y Expresión Génica, Instituto de Nutrición y Tecnología de los Alimentos, Universidad de Chile, Santiago, Chile
| | - Dante Travisany
- Mathomics, Center for Mathematical Modeling, Universidad de Chile, Santiago, Chile.,Center for Genome Regulation (Fondap 15090007), Universidad de Chile, Santiago, Chile
| | - Kavindra V Singh
- Division of Infectious Diseases, Department of Internal Medicine, University of Texas Health Science Center at Houston, Houston, TX, United States.,Center for Antimicrobial Resistance and Microbial Genomics, McGovern Medical School, University of Texas Health Science Center at Houston (UTHealth), Houston, TX, United States
| | - Barbara E Murray
- Division of Infectious Diseases, Department of Internal Medicine, University of Texas Health Science Center at Houston, Houston, TX, United States.,Center for Antimicrobial Resistance and Microbial Genomics, McGovern Medical School, University of Texas Health Science Center at Houston (UTHealth), Houston, TX, United States
| | - Alejandro Maass
- Mathomics, Center for Mathematical Modeling, Universidad de Chile, Santiago, Chile.,Center for Genome Regulation (Fondap 15090007), Universidad de Chile, Santiago, Chile.,Department of Mathematical Engineering, Universidad de Chile, Santiago, Chile
| | - Verónica Cambiazo
- Laboratorio de Bioinformática y Expresión Génica, Instituto de Nutrición y Tecnología de los Alimentos, Universidad de Chile, Santiago, Chile.,Center for Genome Regulation (Fondap 15090007), Universidad de Chile, Santiago, Chile
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Zheng Y, Li Y, Long H, Zhao X, Jia K, Li J, Wang L, Wang R, Lu X, Zhang D. bifA Regulates Biofilm Development of Pseudomonas putida MnB1 as a Primary Response to H 2O 2 and Mn 2. Front Microbiol 2018; 9:1490. [PMID: 30042743 PMCID: PMC6048274 DOI: 10.3389/fmicb.2018.01490] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2018] [Accepted: 06/15/2018] [Indexed: 12/15/2022] Open
Abstract
Pseudomonas putida (P. putida) MnB1 is a widely used model strain in environment science and technology for determining microbial manganese oxidation. Numerous studies have demonstrated that the growth and metabolism of P. putida MnB1 are influenced by various environmental factors. In this study, we investigated the effects of hydrogen peroxide (H2O2) and manganese (Mn2+) on proliferation, Mn2+ acquisition, anti-oxidative system, and biofilm formation of P. putida MnB1. The related orthologs of 4 genes, mco, mntABC, sod, and bifA, were amplified from P. putida GB1 and their involvement were assayed, respectively. We found that P. putida MnB1 degraded H2O2, and quickly recovered for proliferation, but its intracellular oxidative stress state was maintained, with rapid biofilm formation after H2O2 depletion. The data from mco, mntABC, sod and bifA expression levels by qRT-PCR, elucidated a sensitivity toward bifA-mediated biofilm formation, in contrary to intracellular anti-oxidative system under H2O2 exposure. Meanwhile, Mn2+ ion supply inhibited biofilm formation of P. putida MnB1. The expression pattern of these genes showed that Mn2+ ion supply likely functioned to modulate biofilm formation rather than only acting as nutrient substrate for P. putida MnB1. Furthermore, blockade of BifA activity by GTP increased the formation and development of biofilms during H2O2 exposure, while converse response to Mn2+ ion supply was evident. These distinct cellular responses to H2O2 and Mn2+ provide insights on the common mechanism by which environmental microorganisms may be protected from exogenous factors. We postulate that BifA-mediated biofilm formation but not intracellular anti-oxidative system may be a primary protective strategy adopted by P. putida MnB1. These findings will highlight the understanding of microbial adaptation mechanisms to distinct environmental stresses.
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Affiliation(s)
- Yanjing Zheng
- State Key Laboratory of Pharmaceutical Biotechnology, School of Life Sciences, Nanjing University, Nanjing, China
| | - Yumei Li
- State Key Laboratory of Pharmaceutical Biotechnology, School of Life Sciences, Nanjing University, Nanjing, China
| | - Hongyan Long
- State Key Laboratory of Pharmaceutical Biotechnology, School of Life Sciences, Nanjing University, Nanjing, China
| | - Xiaojuan Zhao
- State Key Laboratory of Pharmaceutical Biotechnology, School of Life Sciences, Nanjing University, Nanjing, China
| | - Keke Jia
- State Key Laboratory of Pharmaceutical Biotechnology, School of Life Sciences, Nanjing University, Nanjing, China
| | - Juan Li
- State Key Laboratory for Mineral Deposits Research, School of Earth Sciences and Engineering, Nanjing University, Nanjing, China
| | - Leyong Wang
- Key Laboratory of Mesoscopic Chemistry of MOE and Collaborative Innovation Center of Chemistry for Life Sciences, School of Chemistry and Chemical Engineering, Nanjing, China
| | - Ruiyong Wang
- State Key Laboratory of Pharmaceutical Biotechnology, School of Life Sciences, Nanjing University, Nanjing, China
| | - Xiancai Lu
- State Key Laboratory for Mineral Deposits Research, School of Earth Sciences and Engineering, Nanjing University, Nanjing, China
| | - Dongmei Zhang
- State Key Laboratory of Pharmaceutical Biotechnology, School of Life Sciences, Nanjing University, Nanjing, China
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Soldatova AV, Romano CA, Tao L, Stich TA, Casey WH, Britt RD, Tebo BM, Spiro TG. Mn(II) Oxidation by the Multicopper Oxidase Complex Mnx: A Coordinated Two-Stage Mn(II)/(III) and Mn(III)/(IV) Mechanism. J Am Chem Soc 2017; 139:11381-11391. [PMID: 28712303 DOI: 10.1021/jacs.7b02772] [Citation(s) in RCA: 38] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
The bacterial manganese oxidase MnxG of the Mnx protein complex is unique among multicopper oxidases (MCOs) in carrying out a two-electron metal oxidation, converting Mn(II) to MnO2 nanoparticles. The reaction occurs in two stages: Mn(II) → Mn(III) and Mn(III) → MnO2. In a companion study , we show that the electron transfer from Mn(II) to the low-potential type 1 Cu of MnxG requires an activation step, likely forming a hydroxide bridge at a dinuclear Mn(II) site. Here we study the second oxidation step, using pyrophosphate (PP) as a Mn(III) trap. PP chelates Mn(III) produced by the enzyme and subsequently allows it to become a substrate for the second stage of the reaction. EPR spectroscopy confirms the presence of Mn(III) bound to the enzyme. The Mn(III) oxidation step does not involve direct electron transfer to the enzyme from Mn(III), which is shown by kinetic measurements to be excluded from the Mn(II) binding site. Instead, Mn(III) is proposed to disproportionate at an adjacent polynuclear site, thereby allowing indirect oxidation to Mn(IV) and recycling of Mn(II). PP plays a multifaceted role, slowing the reaction by complexing both Mn(II) and Mn(III) in solution, and also inhibiting catalysis, likely through binding at or near the active site. An overall mechanism for Mnx-catalyzed MnO2 production from Mn(II) is presented.
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Affiliation(s)
- Alexandra V Soldatova
- Department of Chemistry, University of Washington , Box 351700, Seattle, Washington 98195, United States
| | - Christine A Romano
- Division of Environmental and Biomolecular Systems, Institute of Environmental Health, Oregon Health & Science University , Portland, Oregon 97239, United States
| | | | | | | | | | - Bradley M Tebo
- Division of Environmental and Biomolecular Systems, Institute of Environmental Health, Oregon Health & Science University , Portland, Oregon 97239, United States
| | - Thomas G Spiro
- Department of Chemistry, University of Washington , Box 351700, Seattle, Washington 98195, United States
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