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Yu Q, Li H, Du L, Shen L, Zhang J, Yuan L, Yao H, Xiao H, Bai Q, Jia Y, Qiu J, Li Y. Transcriptional regulation of the yersiniabactin receptor fyuA gene by the ferric uptake regulator in Klebsiella pneumoniae NTUH-K2044. J Basic Microbiol 2024; 64:e2400001. [PMID: 38679904 DOI: 10.1002/jobm.202400001] [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: 01/03/2024] [Revised: 04/08/2024] [Accepted: 04/10/2024] [Indexed: 05/01/2024]
Abstract
The ferric uptake regulator (Fur) is a global regulator that influences the expression of virulence genes in Klebsiella pneumoniae. Bioinformatics analysis suggests Fur may involve in iron acquisition via the identified regulatory box upstream of the yersiniabactin receptor gene fyuA. To observe the impact of the gene fyuA on the virulence of K. pneumoniae, the gene fyuA knockout strain and complementation strain were constructed and then conducted a series of phenotypic experiments including chrome azurol S (CAS) detection, crystal violet staining, and wax moth virulence experiment. To examine the regulatory relationship between Fur and the gene fyuA, green fluorescent protein (GFP) reporter gene fusion assay, real-time quantitative reverse transcription polymerase chain reaction (RT-qPCR), gel migration assay (EMSA), and DNase I footprinting assay were used to clarify the regulatory mechanism of Fur on fyuA. CAS detection revealed that the gene fyuA could affect the generation of iron carriers in K. pneumoniae. Crystal violet staining experiment showed that fyuA could positively influence biofilm formation. Wax moth virulence experiment indicated that the deletion of the fyuA could weaken bacterial virulence. GFP reporter gene fusion experiment and RT-qPCR analysis revealed that Fur negatively regulated the expression of fyuA in iron-sufficient environment. EMSA experiment demonstrated that Fur could directly bind to the promoter region of fyuA, and DNase I footprinting assay further identified the specific binding site sequences. The study showed that Fur negatively regulated the transcriptional expression of fyuA by binding to upstream of the gene promoter region, and then affected the virulence of K. pneumoniae.
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Affiliation(s)
- Qian Yu
- School of Public Health, Chongqing Medical University, Chongqing, China
| | - Hailin Li
- School of Public Health, Chongqing Medical University, Chongqing, China
| | - Ling Du
- Chengdu Center for Disease Control and Prevention, Chengdu, Sichuan, China
| | - Lifei Shen
- Jiangbei District Center for Disease Control and Prevention, Jiangbei, Chongqing, China
| | - Jiaxue Zhang
- Jiangbei District Center for Disease Control and Prevention, Jiangbei, Chongqing, China
| | - Lingyue Yuan
- Shanghai Center for Disease Control and Prevention, Shanghai, China
| | - Huang Yao
- School of Public Health, Chongqing Medical University, Chongqing, China
| | - Hong Xiao
- School of Public Health, Chongqing Medical University, Chongqing, China
| | - Qunhua Bai
- School of Public Health, Chongqing Medical University, Chongqing, China
| | - Yan Jia
- School of Public Health, Chongqing Medical University, Chongqing, China
| | - Jingfu Qiu
- School of Public Health, Chongqing Medical University, Chongqing, China
| | - Yingli Li
- School of Public Health, Chongqing Medical University, Chongqing, China
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2
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Hasnat MA, Leimkühler S. Shared functions of Fe-S cluster assembly and Moco biosynthesis. BIOCHIMICA ET BIOPHYSICA ACTA. MOLECULAR CELL RESEARCH 2024; 1871:119731. [PMID: 38631442 DOI: 10.1016/j.bbamcr.2024.119731] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/10/2024] [Revised: 02/29/2024] [Accepted: 04/04/2024] [Indexed: 04/19/2024]
Abstract
Molybdenum cofactor (Moco) biosynthesis is a complex process that involves the coordinated function of several proteins. In the recent years it has become evident that the availability of Fe-S clusters play an important role for the biosynthesis of Moco. First, the MoaA protein binds two [4Fe-4S] clusters per monomer. Second, the expression of the moaABCDE and moeAB operons is regulated by FNR, which senses the availability of oxygen via a functional [4Fe-4S] cluster. Finally, the conversion of cyclic pyranopterin monophosphate to molybdopterin requires the availability of the L-cysteine desulfurase IscS, which is an enzyme involved in the transfer of sulfur to various acceptor proteins with a main role in the assembly of Fe-S clusters. In this review, we dissect the dependence of the production of active molybdoenzymes in detail, starting from the regulation of gene expression and further explaining sulfur delivery and Fe-S cluster insertion into target enzymes. Further, Fe-S cluster assembly is also linked to iron availability. While the abundance of selected molybdoenzymes is largely decreased under iron-limiting conditions, we explain that the expression of the genes is dependent on an active FNR protein. FNR is a very important transcription factor that represents the master-switch for the expression of target genes in response to anaerobiosis. Moco biosynthesis is further directly dependent on the presence of ArcA and also on an active Fur protein.
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Affiliation(s)
- Muhammad Abrar Hasnat
- University of Potsdam, Institute of Biochemistry and Biology, Department of Molecular Enzymology, Karl-Liebknecht Str. 24-25, 14476 Potsdam-Golm, Germany
| | - Silke Leimkühler
- University of Potsdam, Institute of Biochemistry and Biology, Department of Molecular Enzymology, Karl-Liebknecht Str. 24-25, 14476 Potsdam-Golm, Germany.
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3
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Eren E, Watts NR, Montecinos F, Wingfield PT. Encapsulated Ferritin-like Proteins: A Structural Perspective. Biomolecules 2024; 14:624. [PMID: 38927029 PMCID: PMC11202242 DOI: 10.3390/biom14060624] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2024] [Revised: 05/23/2024] [Accepted: 05/24/2024] [Indexed: 06/28/2024] Open
Abstract
Encapsulins are self-assembling nano-compartments that naturally occur in bacteria and archaea. These nano-compartments encapsulate cargo proteins that bind to the shell's interior through specific recognition sequences and perform various metabolic processes. Encapsulation enables organisms to perform chemical reactions without exposing the rest of the cell to potentially harmful substances while shielding cargo molecules from degradation and other adverse effects of the surrounding environment. One particular type of cargo protein, the ferritin-like protein (FLP), is the focus of this review. Encapsulated FLPs are members of the ferritin-like protein superfamily, and they play a crucial role in converting ferrous iron (Fe+2) to ferric iron (Fe+3), which is then stored inside the encapsulin in mineralized form. As such, FLPs regulate iron homeostasis and protect organisms against oxidative stress. Recent studies have demonstrated that FLPs have tremendous potential as biosensors and bioreactors because of their ability to catalyze the oxidation of ferrous iron with high specificity and efficiency. Moreover, they have been investigated as potential targets for therapeutic intervention in cancer drug development and bacterial pathogenesis. Further research will likely lead to new insights and applications for these remarkable proteins in biomedicine and biotechnology.
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Affiliation(s)
| | | | | | - Paul T. Wingfield
- Protein Expression Laboratory, National Institute of Arthritis and Musculoskeletal and Skin Diseases, National Institutes of Health, Bethesda, MD 20892, USA
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Vannini A, Pinatel E, Costantini PE, Pelliciari S, Roncarati D, Puccio S, De Bellis G, Scarlato V, Peano C, Danielli A. (Re)-definition of the holo- and apo-Fur direct regulons of Helicobacter pylori. J Mol Biol 2024; 436:168573. [PMID: 38626867 DOI: 10.1016/j.jmb.2024.168573] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2023] [Revised: 04/09/2024] [Accepted: 04/10/2024] [Indexed: 04/28/2024]
Abstract
Iron homeostasis is a critical process for living organisms because this metal is an essential co-factor for fundamental biochemical activities, like energy production and detoxification, albeit its excess quickly leads to cell intoxication. The protein Fur (ferric uptake regulator) controls iron homeostasis in bacteria by switching from its apo- to holo-form as a function of the cytoplasmic level of ferrous ions, thereby modulating gene expression. The Helicobacter pylori HpFur protein has the rare ability to operate as a transcriptional commutator; apo- and holo-HpFur function as two different repressors with distinct DNA binding recognition properties for specific sets of target genes. Although the regulation of apo- and holo-HpFur in this bacterium has been extensively investigated, we propose a genome-wide redefinition of holo-HpFur direct regulon in H. pylori by integration of RNA-seq and ChIP-seq data, and a large extension of the apo-HpFur direct regulon. We show that in response to iron availability, new coding sequences, non-coding RNAs, toxin-antitoxin systems, and transcripts within open reading frames are directly regulated by apo- or holo-HpFur. These new targets and the more thorough validation and deeper characterization of those already known provide a complete and updated picture of the direct regulons of this two-faced transcriptional regulator.
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Affiliation(s)
- Andrea Vannini
- University of Bologna Department of Pharmacy and Biotechnology, Via Selmi 3, 40126 Bologna, Italy.
| | - Eva Pinatel
- Institute of Biomedical Technologies - National Research Council, Via Fratelli Cervi 93, 20054 Segrate (MI), Italy.
| | - Paolo Emidio Costantini
- University of Bologna Department of Pharmacy and Biotechnology, Via Selmi 3, 40126 Bologna, Italy.
| | - Simone Pelliciari
- Human Genetic Unit, Institute of Genetic and Cancer - University of Edinburgh, Crewe Road, Edinburgh EH4 2XU, UK.
| | - Davide Roncarati
- University of Bologna Department of Pharmacy and Biotechnology, Via Selmi 3, 40126 Bologna, Italy.
| | - Simone Puccio
- Institute of Genetics and Biomedical Research, UoS Milan - National Research Council, Via Manzoni 113, 20089 Rozzano (MI), Italy; Humanitas Clinical and Research Center, Via Manzoni 56, 20089 Rozzano (MI), Italy.
| | - Gianluca De Bellis
- Institute of Biomedical Technologies - National Research Council, Via Fratelli Cervi 93, 20054 Segrate (MI), Italy.
| | - Vincenzo Scarlato
- University of Bologna Department of Pharmacy and Biotechnology, Via Selmi 3, 40126 Bologna, Italy.
| | - Clelia Peano
- Institute of Genetics and Biomedical Research, UoS Milan - National Research Council, Via Manzoni 113, 20089 Rozzano (MI), Italy; Human Technopole, Via Rita Levi Montalcini 1, 20157 Milan, Italy.
| | - Alberto Danielli
- University of Bologna Department of Pharmacy and Biotechnology, Via Selmi 3, 40126 Bologna, Italy.
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Vogt LN, Panis G, Schäpers A, Peschek N, Huber M, Papenfort K, Viollier PH, Fröhlich KS. Genome-wide profiling of Hfq-bound RNAs reveals the iron-responsive small RNA RusT in Caulobacter crescentus. mBio 2024; 15:e0315323. [PMID: 38511926 PMCID: PMC11005374 DOI: 10.1128/mbio.03153-23] [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: 11/21/2023] [Accepted: 02/28/2024] [Indexed: 03/22/2024] Open
Abstract
The alphaproteobacterium Caulobacter crescentus thrives in oligotrophic environments and is able to optimally exploit minimal resources by entertaining an intricate network of gene expression control mechanisms. Numerous transcriptional activators and repressors have been reported to contribute to these processes, but only few studies have focused on regulation at the post-transcriptional level in C. crescentus. Small RNAs (sRNAs) are a prominent class of regulators of bacterial gene expression, and most sRNAs characterized today engage in direct base-pairing interactions to modulate the translation and/or stability of target mRNAs. In many cases, the ubiquitous RNA chaperone, Hfq, contributes to the establishment of RNA-RNA interactions. Although the deletion of the hfq gene is associated with a severe loss of fitness in C. crescentus, the RNA ligands of the chaperone have remained largely unexplored. Here we report on the identification of coding and non-coding transcripts associated with Hfq in C. crescentus and demonstrate Hfq-dependent post-transcriptional regulation in this organism. We show that the Hfq-bound sRNA RusT is transcriptionally controlled by the NtrYX two-component system and induced in response to iron starvation. By combining RusT pulse expression with whole-genome transcriptome analysis, we determine 16 candidate target transcripts that are deregulated, many of which encode outer membrane transporters. We hence suggest RusT to support remodeling of the C. crescentus cell surface when iron supplies are limited.IMPORTANCEThe conserved RNA-binding protein Hfq contributes significantly to the adaptation of bacteria to different environmental conditions. Hfq not only stabilizes associated sRNAs but also promotes inter-molecular base-pairing interactions with target transcripts. Hfq plays a pivotal role for growth and survival, controlling central metabolism and cell wall synthesis in the oligotroph Caulobacter crescentus. However, direct evidence for Hfq-dependent post-transcriptional regulation and potential oligotrophy in C. crescentus has been lacking. Here, we identified sRNAs and mRNAs associated with Hfq in vivo, and demonstrated the requirement of Hfq for sRNA-mediated regulation, particularly of outer membrane transporters in C. crescentus.
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Affiliation(s)
- Laura N. Vogt
- Institute of Microbiology, Faculty of Biological Sciences, Friedrich Schiller University, Jena, Germany
- Department of Biology I, Microbiology, Ludwig-Maximilians-University Munich, Munich, Germany
| | - Gaël Panis
- Department of Microbiology and Molecular Medicine, Faculty of Medicine/Centre Médical Universitaire, University of Geneva, Geneva, Switzerland
| | - Anna Schäpers
- Department of Biology I, Microbiology, Ludwig-Maximilians-University Munich, Munich, Germany
| | - Nikolai Peschek
- Institute of Microbiology, Faculty of Biological Sciences, Friedrich Schiller University, Jena, Germany
- Department of Biology I, Microbiology, Ludwig-Maximilians-University Munich, Munich, Germany
| | - Michaela Huber
- Institute of Microbiology, Faculty of Biological Sciences, Friedrich Schiller University, Jena, Germany
- Department of Biology I, Microbiology, Ludwig-Maximilians-University Munich, Munich, Germany
| | - Kai Papenfort
- Institute of Microbiology, Faculty of Biological Sciences, Friedrich Schiller University, Jena, Germany
- Department of Biology I, Microbiology, Ludwig-Maximilians-University Munich, Munich, Germany
- Cluster of Excellence Balance of the Microverse, Friedrich Schiller University, Jena, Germany
| | - Patrick H. Viollier
- Department of Microbiology and Molecular Medicine, Faculty of Medicine/Centre Médical Universitaire, University of Geneva, Geneva, Switzerland
| | - Kathrin S. Fröhlich
- Institute of Microbiology, Faculty of Biological Sciences, Friedrich Schiller University, Jena, Germany
- Department of Biology I, Microbiology, Ludwig-Maximilians-University Munich, Munich, Germany
- Cluster of Excellence Balance of the Microverse, Friedrich Schiller University, Jena, Germany
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6
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Heffernan JR, Wildenthal JA, Tran H, Katumba GL, McCoy WH, Henderson JP. Yersiniabactin is a quorum-sensing autoinducer and siderophore in uropathogenic Escherichia coli. mBio 2024; 15:e0027723. [PMID: 38236035 PMCID: PMC10865836 DOI: 10.1128/mbio.00277-23] [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: 02/08/2023] [Accepted: 12/07/2023] [Indexed: 01/19/2024] Open
Abstract
Siderophores are secreted ferric ion chelators used to obtain iron in nutrient-limited environmental niches, including human hosts. While all Escherichia coli express the enterobactin (Ent) siderophore system, isolates from patients with urinary tract infections additionally express the genetically distinct yersiniabactin (Ybt) siderophore system. To determine whether the Ent and Ybt systems are functionally redundant for iron uptake, we compared the growth of different isogenic siderophore biosynthetic mutants in the presence of transferrin, a human iron-binding protein. We observed that Ybt expression does not compensate for deficient Ent expression following low-density inoculation. Using transcriptional and product analysis, we found this non-redundancy to be attributable to a density-dependent transcriptional stimulation cycle in which Ybt functions as an autoinducer. These results distinguish the Ybt system as a combined quorum-sensing and siderophore system. These functions may reflect Ybt as a public good within bacterial communities or as an adaptation to confined, subcellular compartments in infected hosts. This combined functionality may contribute to the extraintestinal pathogenic potential of E. coli and related Enterobacterales.IMPORTANCEPatients with urinary tract infections are often infected with Escherichia coli strains carrying adaptations that increase their pathogenic potential. One of these adaptations is the accumulation of multiple siderophore systems, which scavenge iron for nutritional use. While iron uptake is important for bacterial growth, the increased metabolic costs of siderophore production could diminish bacterial fitness during infections. In a siderophore-dependent growth condition, we show that the virulence-associated yersiniabactin siderophore system in uropathogenic E. coli is not redundant with the ubiquitous E. coli enterobactin system. This arises not from differences in iron-scavenging activity but because yersiniabactin is preferentially expressed during bacterial crowding, leaving bacteria dependent upon enterobactin for growth at low cell density. Notably, this regulatory mode arises because yersiniabactin stimulates its own expression, acting as an autoinducer in a previously unappreciated quorum-sensing system. This unexpected result connects quorum-sensing with pathogenic potential in E. coli and related Enterobacterales.
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Affiliation(s)
- James R. Heffernan
- Center for Women’s Infectious Disease Research, Washington University School of Medicine, St. Louis, Missouri, USA
- Division of Infectious Diseases, Washington University School of Medicine, St. Louis, Missouri, USA
- Department of Internal Medicine, Washington University School of Medicine, St. Louis, Missouri, USA
| | - John A. Wildenthal
- Center for Women’s Infectious Disease Research, Washington University School of Medicine, St. Louis, Missouri, USA
- Division of Infectious Diseases, Washington University School of Medicine, St. Louis, Missouri, USA
- Department of Internal Medicine, Washington University School of Medicine, St. Louis, Missouri, USA
| | - Hung Tran
- Center for Women’s Infectious Disease Research, Washington University School of Medicine, St. Louis, Missouri, USA
- Division of Infectious Diseases, Washington University School of Medicine, St. Louis, Missouri, USA
- Department of Internal Medicine, Washington University School of Medicine, St. Louis, Missouri, USA
| | - George L. Katumba
- Center for Women’s Infectious Disease Research, Washington University School of Medicine, St. Louis, Missouri, USA
- Division of Infectious Diseases, Washington University School of Medicine, St. Louis, Missouri, USA
- Department of Internal Medicine, Washington University School of Medicine, St. Louis, Missouri, USA
| | - William H. McCoy
- Division of Dermatology, Washington University School of Medicine, St. Louis, Missouri, USA
- Department of Internal Medicine, Washington University School of Medicine, St. Louis, Missouri, USA
| | - Jeffrey P. Henderson
- Center for Women’s Infectious Disease Research, Washington University School of Medicine, St. Louis, Missouri, USA
- Division of Infectious Diseases, Washington University School of Medicine, St. Louis, Missouri, USA
- Department of Internal Medicine, Washington University School of Medicine, St. Louis, Missouri, USA
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7
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Hasnat MA, Zupok A, Gorka M, Iobbi-Nivol C, Skirycz A, Jourlin-Castelli C, Bier F, Agarwal S, Irefo E, Leimkühler S. Iron limitation indirectly reduces the Escherichia coli torCAD operon expression by a reduction of molybdenum cofactor availability. Microbiol Spectr 2024; 12:e0348023. [PMID: 38193660 PMCID: PMC10845959 DOI: 10.1128/spectrum.03480-23] [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] [Accepted: 11/29/2023] [Indexed: 01/10/2024] Open
Abstract
The expression of most molybdoenzymes in Escherichia coli has so far been revealed to be regulated by anaerobiosis and requires the presence of iron, based on the necessity of the transcription factor FNR to bind one [4Fe-4S] cluster. One exception is trimethylamine-N-oxide reductase encoded by the torCAD operon, which has been described to be expressed independently from FNR. In contrast to other alternative anaerobic respiratory systems, the expression of the torCAD operon was shown not to be completely repressed by the presence of dioxygen. To date, the basis for the O2-dependent expression of the torCAD operon has been related to the abundance of the transcriptional regulator IscR, which represses the transcription of torS and torT, and is more abundant under aerobic conditions than under anaerobic conditions. In this study, we reinvestigated the regulation of the torCAD operon and its dependence on the presence of iron and identified a novel regulation that depends on the presence of the bis-molybdopterin guanine dinucleotide (bis-MGD) molybdenum cofactor . We confirmed that the torCAD operon is directly regulated by the heme-containing protein TorC and is indirectly regulated by ArcA and by the availability of iron via active FNR and Fur, both regulatory proteins that influence the synthesis of the molybdenum cofactor. Furthermore, we identified a novel regulation mode of torCAD expression that is dependent on cellular levels of bis-MGD and is not used by other bis-MGD-containing enzymes like nitrate reductase.IMPORTANCEIn bacteria, molybdoenzymes are crucial for anaerobic respiration using alternative electron acceptors. FNR is a very important transcription factor that represents the master switch for the expression of target genes in response to anaerobiosis. Only Escherichia coli trimethylamine-N-oxide (TMAO) reductase escapes this regulation by FNR. We identified that the expression of TMAO reductase is regulated by the amount of bis-molybdopterin guanine dinucleotide (bis-MGD) cofactor synthesized by the cell itself, representing a novel regulation pathway for the expression of an operon coding for a molybdoenzyme. Furthermore, TMAO reductase gene expression is indirectly regulated by the presence of iron, which is required for the production of the bis-MGD cofactor in the cell.
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Affiliation(s)
- Muhammad Abrar Hasnat
- Department of Molecular Enzymology, Institute of Biochemistry and Biology, University of Potsdam, Potsdam, Germany
| | - Arkadiusz Zupok
- Department of Molecular Enzymology, Institute of Biochemistry and Biology, University of Potsdam, Potsdam, Germany
| | - Michal Gorka
- Max-Planck-Institute of Molecular Plant Physiology, Potsdam, Germany
| | - Chantal Iobbi-Nivol
- Laboratoire de Bioénergétique et Ingénierie des Protéines, Institut de Microbiologie de la Méditerranée, Centre National de la Recherche Scientifique, Aix-Marseille Université, Marseille, France
| | | | - Cécile Jourlin-Castelli
- Laboratoire de Bioénergétique et Ingénierie des Protéines, Institut de Microbiologie de la Méditerranée, Centre National de la Recherche Scientifique, Aix-Marseille Université, Marseille, France
| | - Frank Bier
- Department of Molecular Bioanalytics and Bioelectronics, Institute of Biochemistry and Biology, University of Potsdam, Potsdam, Germany
| | - Saloni Agarwal
- Department of Molecular Bioanalytics and Bioelectronics, Institute of Biochemistry and Biology, University of Potsdam, Potsdam, Germany
| | - Ehizode Irefo
- Department of Molecular Enzymology, Institute of Biochemistry and Biology, University of Potsdam, Potsdam, Germany
| | - Silke Leimkühler
- Department of Molecular Enzymology, Institute of Biochemistry and Biology, University of Potsdam, Potsdam, Germany
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Hakiem OR, Rizvi SMA, Ramirez C, Tan M. Euo is a developmental regulator that represses late genes and activates midcycle genes in Chlamydia trachomatis. mBio 2023; 14:e0046523. [PMID: 37565751 PMCID: PMC10653925 DOI: 10.1128/mbio.00465-23] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2023] [Accepted: 05/22/2023] [Indexed: 08/12/2023] Open
Abstract
IMPORTANCE In this study, we developed a correlative approach that combined DNA immunoprecipitation-seq and RNA-seq analyses to define the regulon of the Chlamydia trachomatis transcription factor Euo. We confirmed the proposed role of Euo as a transcriptional repressor of late chlamydial genes but also showed that Euo activates transcription of a subset of midcycle genes and autoregulates its own expression via negative feedback. This study validates and expands the role of Euo as an important developmental regulator in C. trachomatis. In addition, this genome-wide correlative approach can be applied to study transcription factors in other pathogenic bacteria.
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Affiliation(s)
- Owais R. Hakiem
- Department of Microbiology and Molecular Genetics, University of California Irvine, Irvine, California, USA
| | - Syed M. A. Rizvi
- Department of Microbiology and Molecular Genetics, University of California Irvine, Irvine, California, USA
| | - Cuper Ramirez
- Department of Developmental and Cell Biology, University of California Irvine, Irvine, California, USA
| | - Ming Tan
- Department of Microbiology and Molecular Genetics, University of California Irvine, Irvine, California, USA
- Department of Medicine, University of California Irvine, Irvine, California, USA
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9
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Nandavaram A, Nandakumar A, Kashif GM, Sagar AL, Shailaja G, Ramesh A, Siddavattam D. Unusual Relationship between Iron Deprivation and Organophosphate Hydrolase Expression. Appl Environ Microbiol 2023; 89:e0190322. [PMID: 37074175 PMCID: PMC10231211 DOI: 10.1128/aem.01903-22] [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: 11/15/2022] [Accepted: 03/08/2023] [Indexed: 04/20/2023] Open
Abstract
Organophosphate hydrolases (OPH), hitherto known to hydrolyze the third ester bond of organophosphate (OP) insecticides and nerve agents, have recently been shown to interact with outer membrane transport components, namely, TonB and ExbB/ExbD. In an OPH negative background, Sphingopyxis wildii cells failed to transport ferric enterobactin and showed retarded growth under iron-limiting conditions. We now show the OPH-encoding organophosphate degradation (opd) gene from Sphingobium fuliginis ATCC 27551 to be part of the iron regulon. A fur-box motif found to be overlapping with the transcription start site (TSS) of the opd gene coordinates with an iron responsive element (IRE) RNA motif identified in the 5' coding region of the opd mRNA to tightly regulate opd gene expression. The fur-box motif serves as a target for the Fur repressor in the presence of iron. A decrease in iron concentration leads to the derepression of opd. IRE RNA inhibits the translation of opd mRNA and serves as a target for apo-aconitase (IRP). The IRP recruited by the IRE RNA abrogates IRE-mediated translational inhibition. Our findings establish a novel, multilayered, iron-responsive regulation that is crucial for OPH function in the transport of siderophore-mediated iron uptake. IMPORTANCE Sphingobium fuliginis, a soil-dwelling microbe isolated from agricultural soils, was shown to degrade a variety of insecticides and pesticides. These synthetic chemicals function as potent neurotoxins, and they belong to a class of chemicals termed organophosphates. S. fuliginis codes for OPH, an enzyme that has been shown to be involved in the metabolism of several organophosphates and their derivatives. Interestingly, OPH has also been shown to facilitate siderophore-mediated iron uptake in S. fuliginis and in another Sphingomonad, namely, Sphingopyxis wildii, implying that this organophosphate-metabolizing protein has a role in iron homeostasis, as well. Our research dissects the underlying molecular mechanisms linking iron to the expression of OPH, prompting a reconsideration of the role of OPH in Sphingomonads and a reevaluation of the evolutionary origins of the OPH proteins from soil bacteria.
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Affiliation(s)
- Aparna Nandavaram
- Department of Animal Biology, School of Life Sciences, University of Hyderabad, Hyderabad, India
| | - Anirudh Nandakumar
- National Centre for Biological Sciences, Tata Institute of Fundamental Research, GKVK Campus, Bengaluru, India
- The University of Trans-Disciplinary Health Sciences & Technology (TDU), Bengaluru, Karnataka, India
| | - G. M. Kashif
- Department of Animal Biology, School of Life Sciences, University of Hyderabad, Hyderabad, India
| | | | - G. Shailaja
- Department of Animal Biology, School of Life Sciences, University of Hyderabad, Hyderabad, India
| | - Arati Ramesh
- National Centre for Biological Sciences, Tata Institute of Fundamental Research, GKVK Campus, Bengaluru, India
| | - Dayananda Siddavattam
- Department of Animal Biology, School of Life Sciences, University of Hyderabad, Hyderabad, India
- Department of Biochemistry, School of Sciences, GITAM University, Visakhapatnam, India
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10
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Tzeng YL, Sannigrahi S, Berman Z, Bourne E, Edwards JL, Bazan JA, Turner AN, Moir JWB, Stephens DS. Acquisition of Gonococcal AniA-NorB Pathway by the Neisseria meningitidis Urethritis Clade Confers Denitrifying and Microaerobic Respiration Advantages for Urogenital Adaptation. Infect Immun 2023; 91:e0007923. [PMID: 37092998 PMCID: PMC10187123 DOI: 10.1128/iai.00079-23] [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: 02/22/2023] [Accepted: 03/28/2023] [Indexed: 04/25/2023] Open
Abstract
Neisseria meningitidis historically has been an infrequent and sporadic cause of urethritis and other urogenital infections. However, a nonencapsulated meningococcal clade belonging to the hyperinvasive clonal complex 11.2 lineage has recently emerged and caused clusters of urethritis cases in the United States and other countries. One of the genetic signatures of the emerging N. meningitidis urethritis clade (NmUC) is a chromosomal gene conversion event resulting in the acquisition of the Neisseria gonorrhoeae denitrification apparatus-the N. gonorrhoeae alleles encoding the nitrite reductase AniA, the nitric oxide (NO) reductase NorB, and the intergenic promoter region. The biological importance of the N. gonorrhoeae AniA-NorB for adaptation of the NmUC to a new environmental niche is investigated herein. We found that oxygen consumption, nitrite utilization, and NO production were significantly altered by the conversion event, resulting in different denitrifying aerobic and microaerobic growth of the clade. Further, transcription of aniA and norB in NmUC isolates differed from canonical N. meningitidis, and important polymorphisms within the intergenic region, which influenced aniA promoter activity of the NmUC, were identified. The contributions of three known meningococcal regulators (NsrR, FNR, and NarQP) in controlling the denitrification pathway and endogenous NO metabolism were distinct. Overall, transcription of aniA was dampened relative to canonical N. meningitidis, and this correlated with the lower NO accumulation in the clade. Denitrification and microaerobic respiration were bolstered, and protection against host-derived NO was likely enhanced. The acquisition of the N. gonorrhoeae denitrification pathway by the NmUC supports the clade's adaptation and survival in a microaerobic urogenital environment.
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Affiliation(s)
- Yih-Ling Tzeng
- Division of Infectious Diseases, Department of Medicine, Emory University School of Medicine, Atlanta, Georgia, USA
| | - Soma Sannigrahi
- Division of Infectious Diseases, Department of Medicine, Emory University School of Medicine, Atlanta, Georgia, USA
| | - Zachary Berman
- Division of Infectious Diseases, Department of Medicine, Emory University School of Medicine, Atlanta, Georgia, USA
| | - Emily Bourne
- Department of Biology, University of York, Heslington, York, United Kingdom
| | - Jennifer L. Edwards
- Department of Pediatrics, The Research Institute at Nationwide Children’s Hospital and The Ohio State University, Columbus, Ohio, USA
| | - Jose A. Bazan
- Division of Infectious Diseases, Department of Internal Medicine, The Ohio State University College of Medicine, Columbus, Ohio, USA
- Sexual Health Clinic, Columbus Public Health, Columbus, Ohio, USA
| | - Abigail Norris Turner
- Division of Infectious Diseases, Department of Internal Medicine, The Ohio State University College of Medicine, Columbus, Ohio, USA
| | - James W. B. Moir
- Department of Biology, University of York, Heslington, York, United Kingdom
| | - David S. Stephens
- Division of Infectious Diseases, Department of Medicine, Emory University School of Medicine, Atlanta, Georgia, USA
- Department of Microbiology and Immunology, Emory University School of Medicine, Atlanta, Georgia, USA
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11
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Steingard CH, Helmann JD. Meddling with Metal Sensors: Fur-Family Proteins as Signaling Hubs. J Bacteriol 2023; 205:e0002223. [PMID: 37010421 PMCID: PMC10127796 DOI: 10.1128/jb.00022-23] [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] [Indexed: 04/04/2023] Open
Abstract
The ferric uptake regulator (Fur) protein is the founding member of the FUR superfamily of metalloregulatory proteins that control metal homeostasis in bacteria. FUR proteins regulate metal homeostasis in response to the binding of iron (Fur), zinc (Zur), manganese (Mur), or nickel (Nur). FUR family proteins are generally dimers in solution, but the DNA-bound complex can involve a single dimer, a dimer-of-dimers, or an extended array of bound protein. Elevated FUR levels due to changes in cell physiology increase DNA occupancy and may also kinetically facilitate protein dissociation. Interactions between FUR proteins and other regulators are commonplace, often including cooperative and competitive DNA-binding interactions within the regulatory region. Further, there are many emerging examples of allosteric regulators that interact directly with FUR family proteins. Here, we focus on newly uncovered examples of allosteric regulation by diverse Fur antagonists (Escherichia coli YdiV/SlyD, Salmonella enterica EIIANtr, Vibrio parahaemolyticus FcrX, Acinetobacter baumannii BlsA, Bacillus subtilis YlaN, and Pseudomonas aeruginosa PacT) as well as one Zur antagonist (Mycobacterium bovis CmtR). Small molecules and metal complexes may also serve as regulatory ligands, with examples including heme binding to Bradyrhizobium japonicum Irr and 2-oxoglutarate binding to Anabaena FurA. How these protein-protein and protein-ligand interactions act in conjunction with regulatory metal ions to facilitate signal integration is an active area of investigation.
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Affiliation(s)
| | - John D. Helmann
- Department of Microbiology, Cornell University, Ithaca, New York, USA
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12
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Heffernan JR, Katumba GL, McCoy WH, Henderson JP. Yersiniabactin is a quorum sensing autoinducer and siderophore in uropathogenic Escherichia coli. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.02.09.527953. [PMID: 36798367 PMCID: PMC9934619 DOI: 10.1101/2023.02.09.527953] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/12/2023]
Abstract
Siderophores are secreted ferric ion chelators used to obtain iron in nutrient-limited environmental niches, including human hosts. While all E. coli encode the enterobactin (Ent) siderophore system, isolates from patients with urinary tract infections additionally encode the genetically distinct yersiniabactin (Ybt) siderophore system. To determine whether the Ent and Ybt systems are functionally redundant for iron uptake, we compared growth of different isogenic siderophore biosynthesis mutants in the presence of transferrin, a human iron-binding protein. We observed that the Ybt system does not compensate for loss of the Ent system during siderophore-dependent, low density growth. Using transcriptional and product analysis, we found that this non-redundancy is attributable to a density-dependent transcriptional stimulation cycle in which Ybt assume an additional autoinducer function. These results distinguish the Ybt system as a combined quorum-sensing and siderophore system. These functions may reflect Ybt as a public good within bacterial communities or as an adaptation to confined, subcellular compartments in infected hosts. The efficiency of this arrangement may contribute to the extraintestinal pathogenic potential of E. coli and related Enterobacterales. IMPORTANCE Urinary tract infections (UTIs) are one of the most common human bacterial infections encountered by physicians. Adaptations that increase the pathogenic potential of commensal microbes such as E.coli are of great interest. One potential adaptation observed in clinical isolates is accumulation of multiple siderophore systems, which scavenge iron for nutritional use. While iron uptake is important for bacterial growth, the increased metabolic costs of siderophore production could diminish bacterial fitness during infections. In a siderophore-dependent growth conditions, we show that the virulence-associated yersiniabactin siderophore system in uropathogenic E. coli is not redundant with the ubiquitous E. coli enterobactin system. This arises not from differences in iron scavenging activity but because yersiniabactin is preferentially expressed during bacterial crowding, leaving bacteria dependent upon enterobactin for growth at low cell density. Notably, this regulatory mode arises because yersiniabactin stimulates its own expression, acting as an autoinducer in a previously unappreciated quorum-sensing system. This unexpected result connects quorum-sensing with pathogenic potential in E. coli and related Enterobacterales.
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13
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Saldaña-Ahuactzi Z, Knodler LA. FoxR is an AraC-like transcriptional regulator of ferrioxamine uptake in Salmonella enterica. Mol Microbiol 2022; 118:369-386. [PMID: 35970762 DOI: 10.1111/mmi.14970] [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: 03/23/2022] [Revised: 07/30/2022] [Accepted: 08/02/2022] [Indexed: 01/07/2023]
Abstract
Salmonella enterica spp. produce siderophores to bind iron with high affinity and can also use three xenosiderophores secreted by other microorganisms, ferrichrome, coprogen, and ferrioxamine. Here we focused on FoxA, a TonB-dependent transporter of ferrioxamines. Adjacent to foxA is a gene annotated as a helix-turn-helix (HTH) domain-containing protein, SL0358 (foxR), in the Salmonella enterica serovar Typhimurium SL1344 genome. FoxR shares homology with transcriptional regulators belonging to the AraC/XylS family. foxR is syntenic with foxA in the Enterobacteriaceae family, suggesting their functional relatedness. Both foxA and foxR are repressed by the ferric uptake regulator (Fur) under iron-rich growth conditions. When iron is scarce, FoxR acts as a transcriptional activator of foxA by directly binding to its upstream regulatory region. A point mutation in the HTH domain of FoxR abolished this binding, as did mutation of a direct repeat motif in the foxA upstream regulatory region. Desferrioxamine (DFOE) enhanced FoxR protein stability and foxA transcription but did not affect the affinity of FoxR binding to the foxA regulatory region. In summary, we have identified FoxR as a new member of the AraC/XylS family that regulates xenosiderophore-mediated iron uptake by S. Typhimurium and likely other Enterobacteriaceae members.
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Affiliation(s)
- Zeus Saldaña-Ahuactzi
- Paul G. Allen School for Global Health, College of Veterinary Medicine, Washington State University, Pullman, Washington, USA
| | - Leigh A Knodler
- Paul G. Allen School for Global Health, College of Veterinary Medicine, Washington State University, Pullman, Washington, USA
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14
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Imelio JA, Trajtenberg F, Buschiazzo A. Allostery and protein plasticity: the keystones for bacterial signaling and regulation. Biophys Rev 2022; 13:943-953. [PMID: 35059019 DOI: 10.1007/s12551-021-00892-9] [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: 09/10/2021] [Accepted: 10/31/2021] [Indexed: 11/25/2022] Open
Abstract
Bacteria sense intracellular and environmental signals using an array of proteins as antennas. The information is transmitted from such sensory modules to other protein domains that act as output effectors. Sensor and effector can be part of the same polypeptide or instead be separate diffusible proteins that interact specifically. The output effector modules regulate physiologic responses, allowing the cells to adapt to the varying conditions. These biological machineries are known as signal transduction systems (STSs). Despite the captivating architectural diversity exhibited by STS proteins, a universal feature is their allosteric regulation: signal binding at one site modifies the activity at a physically distant site. Allostery requires protein plasticity, precisely encoded within their 3D structures, and implicating programmed molecular motions. This review summarizes how STS proteins connect stimuli to specific responses by exploiting allostery and protein plasticity. Illustrative examples spanning a wide variety of protein folds will focus on one- and two-component systems (TCSs). The former encompass the entire transmission route within a single polypeptide, whereas TCSs have evolved as separate diffusible proteins that interact specifically, sometimes including additional intermediary proteins in the pathway. Irrespective of their structural diversity, STS proteins are able to modulate their own molecular motions, which can be relatively slow, rigid-body movements, all the way to fast fluctuations in the form of macromolecular flexibility, thus spanning a continuous protein dynamics spectrum. In sum, STSs rely on allostery to steer information transmission, going from simple two-state switching to rich multi-state conformational order/disorder transitions.
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Affiliation(s)
- J A Imelio
- Laboratory of Molecular & Structural Microbiology, Institut Pasteur de Montevideo, Montevideo, Uruguay
| | - F Trajtenberg
- Laboratory of Molecular & Structural Microbiology, Institut Pasteur de Montevideo, Montevideo, Uruguay
| | - A Buschiazzo
- Laboratory of Molecular & Structural Microbiology, Institut Pasteur de Montevideo, Montevideo, Uruguay
- Department of Microbiology, Institut Pasteur, Paris, France
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15
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Grassmann AA, Zavala-Alvarado C, Bettin EB, Picardeau M, Benaroudj N, Caimano MJ. The FUR-like regulators PerRA and PerRB integrate a complex regulatory network that promotes mammalian host-adaptation and virulence of Leptospira interrogans. PLoS Pathog 2021; 17:e1009078. [PMID: 34855918 PMCID: PMC8638967 DOI: 10.1371/journal.ppat.1009078] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2020] [Accepted: 02/18/2021] [Indexed: 11/18/2022] Open
Abstract
Leptospira interrogans, the causative agent of most cases of human leptospirosis, must respond to myriad environmental signals during its free-living and pathogenic lifestyles. Previously, we compared L. interrogans cultivated in vitro and in vivo using a dialysis membrane chamber (DMC) peritoneal implant model. From these studies emerged the importance of genes encoding the Peroxide responsive regulators PerRA and PerRB. First described in in Bacillus subtilis, PerRs are widespread in Gram-negative and -positive bacteria, where regulate the expression of gene products involved in detoxification of reactive oxygen species and virulence. Using perRA and perRB single and double mutants, we establish that L. interrogans requires at least one functional PerR for infectivity and renal colonization in a reservoir host. Our finding that the perRA/B double mutant survives at wild-type levels in DMCs is noteworthy as it demonstrates that the loss of virulence is not due to a metabolic lesion (i.e., metal starvation) but instead reflects dysregulation of virulence-related gene products. Comparative RNA-Seq analyses of perRA, perRB and perRA/B mutants cultivated within DMCs identified 106 genes that are dysregulated in the double mutant, including ligA, ligB and lvrA/B sensory histidine kinases. Decreased expression of LigA and LigB in the perRA/B mutant was not due to loss of LvrAB signaling. The majority of genes in the perRA and perRB single and double mutant DMC regulons were differentially expressed only in vivo, highlighting the importance of host signals for regulating gene expression in L. interrogans. Importantly, the PerRA, PerRB and PerRA/B DMC regulons each contain multiple genes related to environmental sensing and/or transcriptional regulation. Collectively, our data suggest that PerRA and PerRB are part of a complex regulatory network that promotes host adaptation by L. interrogans within mammals.
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Affiliation(s)
- André A. Grassmann
- Department of Medicine, University of Connecticut Health, Farmington, Connecticut, United States of America
| | - Crispin Zavala-Alvarado
- Unité de Biologie des Spirochètes, Department of Microbiology, Institut Pasteur, Paris, France
- Université de Paris, Sorbonne Paris Cité, Communauté d’universités et d’établissements (COMUE), Bio Sorbonne Paris Cité (BioSPC), Paris, France
| | - Everton B. Bettin
- Department of Medicine, University of Connecticut Health, Farmington, Connecticut, United States of America
- Programa de Pós-Graduação em Biotecnologia, Centro de Desenvolvimento Tecnológico, Universidade Federal de Pelotas, Pelotas, Rio Grande do Sol, Brazil
| | - Mathieu Picardeau
- Unité de Biologie des Spirochètes, Department of Microbiology, Institut Pasteur, Paris, France
| | - Nadia Benaroudj
- Unité de Biologie des Spirochètes, Department of Microbiology, Institut Pasteur, Paris, France
| | - Melissa J. Caimano
- Department of Medicine, University of Connecticut Health, Farmington, Connecticut, United States of America
- Department of Pediatrics, University of Connecticut Health, Farmington, Connecticut, United States of America
- Department of Molecular Biology and Biophysics, University of Connecticut Health, Farmington, Connecticut, United States of America
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16
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A protease-mediated mechanism regulates the cytochrome c 6/plastocyanin switch in Synechocystis sp. PCC 6803. Proc Natl Acad Sci U S A 2021; 118:2017898118. [PMID: 33495331 DOI: 10.1073/pnas.2017898118] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
After the Great Oxidation Event (GOE), iron availability was greatly decreased, and photosynthetic organisms evolved several alternative proteins and mechanisms. One of these proteins, plastocyanin, is a type I blue-copper protein that can replace cytochrome c 6 as a soluble electron carrier between cytochrome b 6 f and photosystem I. In most cyanobacteria, expression of these two alternative proteins is regulated by copper availability, but the regulatory system remains unknown. Herein, we provide evidence that the regulatory system is composed of a BlaI/CopY-family transcription factor (PetR) and a BlaR-membrane protease (PetP). PetR represses petE (plastocyanin) expression and activates petJ (cytochrome c 6), while PetP controls PetR levels in vivo. Using whole-cell extracts, we demonstrated that PetR degradation requires both PetP and copper. Transcriptomic analysis revealed that the PetRP system regulates only four genes (petE, petJ, slr0601, and slr0602), highlighting its specificity. Furthermore, the presence of petE and petRP in early branching cyanobacteria indicates that acquisition of these genes could represent an early adaptation to decreased iron bioavailability following the GOE.
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17
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Bradley JM, Svistunenko DA, Wilson MT, Hemmings AM, Moore GR, Le Brun NE. Bacterial iron detoxification at the molecular level. J Biol Chem 2021; 295:17602-17623. [PMID: 33454001 PMCID: PMC7762939 DOI: 10.1074/jbc.rev120.007746] [Citation(s) in RCA: 49] [Impact Index Per Article: 16.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2020] [Revised: 10/07/2020] [Indexed: 01/18/2023] Open
Abstract
Iron is an essential micronutrient, and, in the case of bacteria, its availability is commonly a growth-limiting factor. However, correct functioning of cells requires that the labile pool of chelatable "free" iron be tightly regulated. Correct metalation of proteins requiring iron as a cofactor demands that such a readily accessible source of iron exist, but overaccumulation results in an oxidative burden that, if unchecked, would lead to cell death. The toxicity of iron stems from its potential to catalyze formation of reactive oxygen species that, in addition to causing damage to biological molecules, can also lead to the formation of reactive nitrogen species. To avoid iron-mediated oxidative stress, bacteria utilize iron-dependent global regulators to sense the iron status of the cell and regulate the expression of proteins involved in the acquisition, storage, and efflux of iron accordingly. Here, we survey the current understanding of the structure and mechanism of the important members of each of these classes of protein. Diversity in the details of iron homeostasis mechanisms reflect the differing nutritional stresses resulting from the wide variety of ecological niches that bacteria inhabit. However, in this review, we seek to highlight the similarities of iron homeostasis between different bacteria, while acknowledging important variations. In this way, we hope to illustrate how bacteria have evolved common approaches to overcome the dual problems of the insolubility and potential toxicity of iron.
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Affiliation(s)
- Justin M Bradley
- Centre for Molecular and Structural Biochemistry, School of Chemistry, University of East Anglia, Norwich, United Kingdom.
| | | | - Michael T Wilson
- School of Life Sciences, University of Essex, Colchester, United Kingdom
| | - Andrew M Hemmings
- Centre for Molecular and Structural Biochemistry, School of Chemistry, University of East Anglia, Norwich, United Kingdom; Centre for Molecular and Structural Biochemistry, School of Biological Sciences, University of East Anglia, Norwich, United Kingdom
| | - Geoffrey R Moore
- Centre for Molecular and Structural Biochemistry, School of Chemistry, University of East Anglia, Norwich, United Kingdom
| | - Nick E Le Brun
- Centre for Molecular and Structural Biochemistry, School of Chemistry, University of East Anglia, Norwich, United Kingdom.
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18
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Gomes AÉI, Pacheco T, Dos Santos CDS, Pereira JA, Ribeiro ML, Darrieux M, Ferraz LFC. Functional Insights From KpfR, a New Transcriptional Regulator of Fimbrial Expression That Is Crucial for Klebsiella pneumoniae Pathogenicity. Front Microbiol 2021; 11:601921. [PMID: 33552015 PMCID: PMC7861041 DOI: 10.3389/fmicb.2020.601921] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2020] [Accepted: 12/03/2020] [Indexed: 12/17/2022] Open
Abstract
Although originally known as an opportunistic pathogen, Klebsiella pneumoniae has been considered a worldwide health threat nowadays due to the emergence of hypervirulent and antibiotic-resistant strains capable of causing severe infections not only on immunocompromised patients but also on healthy individuals. Fimbriae is an essential virulence factor for K. pneumoniae, especially in urinary tract infections (UTIs), because it allows the pathogen to adhere and invade urothelial cells and to form biofilms on biotic and abiotic surfaces. The importance of fimbriae for K. pneumoniae pathogenicity is highlighted by the large number of fimbrial gene clusters on the bacterium genome, which requires a coordinated and finely adjusted system to control the synthesis of these structures. In this work, we describe KpfR as a new transcriptional repressor of fimbrial expression in K. pneumoniae and discuss its role in the bacterium pathogenicity. K. pneumoniae with disrupted kpfR gene exhibited a hyperfimbriated phenotype with enhanced biofilm formation and greater adhesion to and replication within epithelial host cells. Nonetheless, the mutant strain was attenuated for colonization of the bladder in a murine model of urinary tract infection. These results indicate that KpfR is an important transcriptional repressor that, by negatively controlling the expression of fimbriae, prevents K. pneumoniae from having a hyperfimbriated phenotype and from being recognized and eliminated by the host immune system.
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Affiliation(s)
- Ana Érika Inácio Gomes
- Laboratório de Biologia Molecular de Microrganismos, Universidade São Francisco, Bragança Paulista, Brazil
| | - Thaisy Pacheco
- Laboratório de Biologia Molecular de Microrganismos, Universidade São Francisco, Bragança Paulista, Brazil
| | | | - José Aires Pereira
- Laboratório de Biologia Molecular e Celular de Tumores, Universidade São Francisco, Bragança Paulista, Brazil
| | - Marcelo Lima Ribeiro
- Laboratório de Imunofarmacologia e Biologia Molecular, Universidade São Francisco, Bragança Paulista, Brazil
| | - Michelle Darrieux
- Laboratório de Biologia Molecular de Microrganismos, Universidade São Francisco, Bragança Paulista, Brazil
| | - Lúcio Fábio Caldas Ferraz
- Laboratório de Biologia Molecular de Microrganismos, Universidade São Francisco, Bragança Paulista, Brazil
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Ferric Uptake Regulator Fur Coordinates Siderophore Production and Defense against Iron Toxicity and Oxidative Stress and Contributes to Virulence in Chromobacterium violaceum. Appl Environ Microbiol 2020; 86:AEM.01620-20. [PMID: 32859594 DOI: 10.1128/aem.01620-20] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2020] [Accepted: 08/20/2020] [Indexed: 12/27/2022] Open
Abstract
Iron is a highly reactive metal that participates in several processes in prokaryotic and eukaryotic cells. Hosts and pathogens compete for iron in the context of infection. Chromobacterium violaceum, an environmental Gram-negative bacterial pathogen, relies on siderophores to overcome iron limitation in the host. In this work, we studied the role of the ferric uptake regulator Fur in the physiology and virulence of C. violaceum A Δfur mutant strain showed decreased growth and fitness under regular in vitro growth conditions and presented high sensitivity to iron and oxidative stresses. Furthermore, the absence of fur caused derepression of siderophore production and reduction in swimming motility and biofilm formation. Consistent with these results, the C. violaceum Δfur mutant was highly attenuated for virulence and liver colonization in mice. In contrast, a manganese-selected spontaneous fur mutant showed only siderophore overproduction and sensitivity to oxidative stress, indicating that Fur remained partially functional in this strain. We found that mutations in genes related to siderophore biosynthesis and a putative CRISPR-Cas locus rescued the Δfur mutant growth defects, indicating that multiple Fur-regulated processes contribute to maintaining bacterial cell fitness. Overall, our data indicated that Fur is conditionally essential in C. violaceum mainly by protecting cells from iron overload and oxidative damage. The requirement of Fur for virulence highlights the importance of iron in the pathogenesis of C. violaceum IMPORTANCE Maintenance of iron homeostasis, i.e., avoiding both deficiency and toxicity of this metal, is vital to bacteria and their hosts. Iron sequestration by host proteins is a crucial strategy to combat bacterial infections. In bacteria, the ferric uptake regulator Fur coordinates the expression of several iron-related genes. Sometimes, Fur can also regulate several other processes. In this work, we performed an in-depth phenotypic characterization of fur mutants in the human opportunistic pathogen Chromobacterium violaceum We determined that fur is a conditionally essential gene necessary for proper growth under regular conditions and is fully required for survival under iron and oxidative stresses. Fur also controlled several virulence-associated traits, such as swimming motility, biofilm formation, and siderophore production. Consistent with these results, a C. violaceum fur null mutant showed attenuation of virulence. Therefore, our data established Fur as a major player required for C. violaceum to manage iron, including during infection in the host.
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20
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Bacillus subtilis Fur Is a Transcriptional Activator for the PerR-Repressed pfeT Gene, Encoding an Iron Efflux Pump. J Bacteriol 2020; 202:JB.00697-19. [PMID: 31988078 DOI: 10.1128/jb.00697-19] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2019] [Accepted: 01/23/2020] [Indexed: 12/30/2022] Open
Abstract
The physiological relevance of bacterial iron efflux has only recently been appreciated. The Bacillus subtilis P1B4-type ATPase PfeT (peroxide-induced ferrous efflux transporter) was one of the first iron efflux pumps to be characterized, and cells lacking pfeT accumulate high levels of intracellular iron. The pfeT promoter region has binding sites for both PerR, a peroxide-sensing Fur-family metalloregulator, and the ferric uptake repressor Fur. Both Fur and PerR bind DNA with Fe(II) as a cofactor. While reaction of PerR-Fe(II) with peroxide can account for the induction of pfeT under oxidative stress, binding of Fur-Fe(II) would be expected to lead to repression, which is inconsistent with the known role of PfeT as an iron efflux protein. Here, we show that expression of pfeT is repressed by PerR, as anticipated, and induced by Fur in response to Fe(II). Activation by Fur is mediated both by antagonism of the PerR repressor and by direct transcriptional activation, as confirmed using in vitro transcription assays. A similar mechanism of regulation can explain the iron induction of the Listeria monocytogenes PfeT ortholog and virulence factor, FrvA. Mutational studies support a model in which Fur activation involves regions both upstream and downstream of the pfeT promoter, and Fur and PerR have overlapping recognition of a shared regulatory element in this complex promoter region. This work demonstrates that B. subtilis Fur can function as an iron-dependent activator of transcription.IMPORTANCE Iron homeostasis plays a key role at the host-pathogen interface during the process of infection. Bacterial growth restriction resulting from host-imposed iron starvation (nutritional immunity) highlights the importance of iron import during pathogenesis. Conversely, bacterial iron efflux pumps function as virulence factors in several systems. The requirement for iron efflux in pathogens such as Listeria monocytogenes, Streptococcus pyogenes, and Mycobacterium tuberculosis suggests that both import and efflux are needed for cells to successfully navigate rapidly changing levels of iron availability in the host. Here, we provide insight into how iron efflux genes are controlled, an aspect of bacterial iron homeostasis relevant to infectious disease processes.
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21
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Shyntum DY, Nkomo NP, Shingange NL, Gricia AR, Bellieny-Rabelo D, Moleleki LN. The Impact of Type VI Secretion System, Bacteriocins and Antibiotics on Bacterial Competition of Pectobacterium carotovorum subsp. brasiliense and the Regulation of Carbapenem Biosynthesis by Iron and the Ferric-Uptake Regulator. Front Microbiol 2019; 10:2379. [PMID: 31681235 PMCID: PMC6813493 DOI: 10.3389/fmicb.2019.02379] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2019] [Accepted: 09/30/2019] [Indexed: 12/17/2022] Open
Abstract
The complexity of plant microbial communities provides a rich model for investigating biochemical and regulatory strategies involved in interbacterial competition. Within these niches, the soft rot Enterobacteriaceae (SRE) represents an emerging group of plant-pathogens causing soft rot/blackleg diseases resulting in economic losses worldwide in a variety of crops. A preliminary screening using next-generation sequencing of 16S rRNA comparatively analyzing healthy and diseased potato tubers, identified several taxa from Proteobacteria to Firmicutes as potential potato endophytes/plant pathogens. Subsequent to this, a range of molecular and computational techniques were used to determine the contribution of antimicrobial factors such as bacteriocins, carbapenem and type VI secretion system (T6SS), found in an aggressive SRE (Pectobacterium carotovorum subsp. brasiliense strain PBR1692 - Pcb1692) against these endophytes/plant pathogens. The results showed growth inhibition of several Proteobacteria by Pcb1692 depends either on carbapenem or pyocin production. Whereas for targeted Firmicutes, only the Pcb1692 pyocin seems to play a role in growth inhibition. Furthermore, production of carbapenem by Pcb1692 was observably dependent on the presence of environmental iron and oxygen. Additionally, upon deletion of fur, slyA and expI regulators, carbapenem production ceased, implying a complex regulatory mechanism involving these three genes. Finally, the results demonstrated that although T6SS confers no relevant advantage during in vitro competition, a significant attenuation in competition by the mutant strain lacking a functional T6SS was observed in planta. IMPORTANCE Soft rot Enterobacteriaceae (SRE) represents important phytopathogens causing soft rot/blackleg diseases in a variety of crops leading to huge economic losses worldwide. These pathogens have been isolated alongside other bacteria from different environments such as potato tubers, stems, roots and from the soil. In these environments, SREs coexist with other bacteria where they have to compete for scarce nutrients and other resources. In this report, we show that Pectobacterium carotovorum subsp. brasiliense strain PBR1692 - Pcb1692, which represents one of the SREs, inhibits growth of several different bacteria by producing different antimicrobial compounds. These antimicrobial compounds can be secreted inside or outside the plant host, allowing Pcb1692 to effectively colonize different types of ecological niches. By analyzing the genome sequences of several SREs, we show that other SREs likely deploy similar antimicrobials to target other bacteria.
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Affiliation(s)
- Divine Yufetar Shyntum
- Department of Biochemistry, Genetics and Microbiology, University of Pretoria, Pretoria, South Africa
- Forestry, Agriculture and Biotechnology Institute, University of Pretoria, Pretoria, South Africa
| | - Ntombikayise Precious Nkomo
- Department of Biochemistry, Genetics and Microbiology, University of Pretoria, Pretoria, South Africa
- Forestry, Agriculture and Biotechnology Institute, University of Pretoria, Pretoria, South Africa
| | - Ntwanano Luann Shingange
- Department of Biochemistry, Genetics and Microbiology, University of Pretoria, Pretoria, South Africa
| | - Alessandro Rino Gricia
- Department of Biochemistry, Genetics and Microbiology, University of Pretoria, Pretoria, South Africa
- Forestry, Agriculture and Biotechnology Institute, University of Pretoria, Pretoria, South Africa
| | - Daniel Bellieny-Rabelo
- Department of Biochemistry, Genetics and Microbiology, University of Pretoria, Pretoria, South Africa
- Forestry, Agriculture and Biotechnology Institute, University of Pretoria, Pretoria, South Africa
| | - Lucy Novungayo Moleleki
- Department of Biochemistry, Genetics and Microbiology, University of Pretoria, Pretoria, South Africa
- Forestry, Agriculture and Biotechnology Institute, University of Pretoria, Pretoria, South Africa
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22
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Zhang P, Ye Z, Ye C, Zou H, Gao Z, Pan J. OmpW is positively regulated by iron via Fur, and negatively regulated by SoxS contribution to oxidative stress resistance in Escherichia coli. Microb Pathog 2019; 138:103808. [PMID: 31634530 DOI: 10.1016/j.micpath.2019.103808] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2019] [Revised: 10/04/2019] [Accepted: 10/16/2019] [Indexed: 10/25/2022]
Abstract
Iron plays a central role at the interface of pathogen and host. The ability to sequester iron from a host not only reduces host immune defenses but also promotes pathogen virulence, leading to the occurrence of infectious disease. Recently, outer membrane protein OmpW was shown to protect bacteria against harsh environmental conditions and to play a role in infectious disease. The expression of this versatile protein is controlled by iron, but the underlying mechanism of iron regulation has not been elucidated. In this study, the relation between OmpW expression and iron was investigated. Our results demonstrated that expression of OmpW is responsive to iron. Iron uptake analysis showed that an ompW mutant strain has a strong requirement for iron as compared to wild type and the ompW complemented strain. Moreover, ferric uptake regulation protein Fur, an iron binding transcriptional factor, was downregulated under iron limitation conditions and had a similar expression profile to OmpW in the presence or absence of iron. Based on these results, we suggest that iron regulates OmpW by binding to Fur. Furthermore, SoxS, a transcriptional factor involved in oxidative stress, was found to negatively regulate OmpW. We found that downregulating or knocking out OmpW results in bacterial resistance to oxidative stress. These findings provide new insight into the regulation of OmpW expression by iron, and may represent a new mechanism contributing to iron-mediated infectious disease.
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Affiliation(s)
- Pengfei Zhang
- Zhejiang Provincial Key Laboratory of Silkworm Bioreactor and Biomedicine, School of Life Sciences and Medicine, Zhejiang Sci-Tech University, Hangzhou, 310018, China
| | - Zhicang Ye
- Zhejiang Provincial Key Laboratory of Silkworm Bioreactor and Biomedicine, School of Life Sciences and Medicine, Zhejiang Sci-Tech University, Hangzhou, 310018, China
| | - Chen Ye
- Zhejiang Provincial Key Laboratory of Silkworm Bioreactor and Biomedicine, School of Life Sciences and Medicine, Zhejiang Sci-Tech University, Hangzhou, 310018, China
| | - Haijie Zou
- Zhejiang Provincial Key Laboratory of Silkworm Bioreactor and Biomedicine, School of Life Sciences and Medicine, Zhejiang Sci-Tech University, Hangzhou, 310018, China
| | - Zhichao Gao
- Zhejiang Provincial Key Laboratory of Silkworm Bioreactor and Biomedicine, School of Life Sciences and Medicine, Zhejiang Sci-Tech University, Hangzhou, 310018, China
| | - Jianyi Pan
- Zhejiang Provincial Key Laboratory of Silkworm Bioreactor and Biomedicine, School of Life Sciences and Medicine, Zhejiang Sci-Tech University, Hangzhou, 310018, China.
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23
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Graves JL, Ewunkem AJ, Ward J, Staley C, Thomas MD, Rhinehardt KL, Han J, Harrison SH. Experimental evolution of gallium resistance in Escherichia coli. EVOLUTION MEDICINE AND PUBLIC HEALTH 2019; 2019:169-180. [PMID: 31890209 PMCID: PMC6928379 DOI: 10.1093/emph/eoz025] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/29/2018] [Accepted: 08/29/2019] [Indexed: 12/26/2022]
Abstract
Background and Objectives Metallic antimicrobial materials are of growing interest due to their potential to control pathogenic and multidrug-resistant bacteria. Yet we do not know if utilizing these materials can lead to genetic adaptations that produce even more dangerous bacterial varieties. Methodology Here we utilize experimental evolution to produce strains of Escherichia coli K-12 MG1655 resistant to, the iron analog, gallium nitrate (Ga(NO3)3). Whole genome sequencing was utilized to determine genomic changes associated with gallium resistance. Computational modeling was utilized to propose potential molecular mechanisms of resistance. Results By day 10 of evolution, increased gallium resistance was evident in populations cultured in medium containing a sublethal concentration of gallium. Furthermore, these populations showed increased resistance to ionic silver and iron (III), but not iron (II) and no increase in traditional antibiotic resistance compared with controls and the ancestral strain. In contrast, the control populations showed increased resistance to rifampicin relative to the gallium-resistant and ancestral population. Genomic analysis identified hard selective sweeps of mutations in several genes in the gallium (III)-resistant lines including: fecA (iron citrate outer membrane transporter), insl1 (IS30 tranposase) one intergenic mutations arsC →/→ yhiS; (arsenate reductase/pseudogene) and in one pseudogene yedN ←; (iapH/yopM family). Two additional significant intergenic polymorphisms were found at frequencies > 0.500 in fepD ←/→ entS (iron-enterobactin transporter subunit/enterobactin exporter, iron-regulated) and yfgF ←/→ yfgG (cyclic-di-GMP phosphodiesterase, anaerobic/uncharacterized protein). The control populations displayed mutations in the rpoB gene, a gene associated with rifampicin resistance. Conclusions This study corroborates recent results observed in experiments utilizing pathogenic Pseudomonas strains that also showed that Gram-negative bacteria can rapidly evolve resistance to an atom that mimics an essential micronutrient and shows the pleiotropic consequences associated with this adaptation. Lay summary We utilize experimental evolution to produce strains of Escherichia coli K-12 MG1655 resistant to, the iron analog, gallium nitrate (Ga(NO3)3). Whole genome sequencing was utilized to determine genomic changes associated with gallium resistance. Computational modeling was utilized to propose potential molecular mechanisms of resistance.
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Affiliation(s)
- Joseph L Graves
- Department of Nanoengineering, Joint School of Nanoscience & Nanoengineering, North Carolina A&T State University & UNC Greensboro, Greensboro, NC, USA.,BEACON Center for the Study of Evolution in Action, Michigan State University, East Lansing, MI, USA
| | - Akamu J Ewunkem
- Department of Nanoengineering, Joint School of Nanoscience & Nanoengineering, North Carolina A&T State University & UNC Greensboro, Greensboro, NC, USA.,BEACON Center for the Study of Evolution in Action, Michigan State University, East Lansing, MI, USA
| | - Jason Ward
- High School Science Teacher, Davie Public High School, Davie, NC, USA
| | | | - Misty D Thomas
- BEACON Center for the Study of Evolution in Action, Michigan State University, East Lansing, MI, USA.,Department of Biology, North Carolina A&T State University, Greensboro, NC, USA
| | - Kristen L Rhinehardt
- Department of Nanoengineering, Joint School of Nanoscience & Nanoengineering, North Carolina A&T State University & UNC Greensboro, Greensboro, NC, USA.,BEACON Center for the Study of Evolution in Action, Michigan State University, East Lansing, MI, USA
| | - Jian Han
- BEACON Center for the Study of Evolution in Action, Michigan State University, East Lansing, MI, USA.,Department of Biology, North Carolina A&T State University, Greensboro, NC, USA
| | - Scott H Harrison
- BEACON Center for the Study of Evolution in Action, Michigan State University, East Lansing, MI, USA.,Department of Biology, North Carolina A&T State University, Greensboro, NC, USA
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24
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Seib KL, Haag AF, Oriente F, Fantappiè L, Borghi S, Semchenko EA, Schulz BL, Ferlicca F, Taddei AR, Giuliani MM, Pizza M, Delany I. The meningococcal vaccine antigen GNA2091 is an analogue of YraP and plays key roles in outer membrane stability and virulence. FASEB J 2019; 33:12324-12335. [DOI: 10.1096/fj.201900669r] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Kate L. Seib
- Institute for GlycomicsGriffith UniversityGold CoastQueenslandAustralia
| | | | | | | | | | | | - Benjamin L. Schulz
- School of Chemistry and Molecular BiosciencesThe University of QueenslandBrisbaneQueenslandAustralia
| | | | - Anna Rita Taddei
- Interdepartmental Centre of Electron Microscopy (CIME)Tuscia UniversityTusciaItaly
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25
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Śmiga M, Bielecki M, Olczak M, Olczak T. Porphyromonas gingivalis PgFur Is a Member of a Novel Fur Subfamily With Non-canonical Function. Front Cell Infect Microbiol 2019; 9:233. [PMID: 31312617 PMCID: PMC6613475 DOI: 10.3389/fcimb.2019.00233] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2019] [Accepted: 06/14/2019] [Indexed: 12/11/2022] Open
Abstract
Porphyromonas gingivalis, a keystone pathogen of chronic periodontitis, uses ferric uptake regulator homolog (PgFur) to regulate production of virulence factors. This study aimed to characterize PgFur protein in regard to its structure-function relationship. We experimentally identified the 5′ mRNA sequence encoding the 171-amino-acid-long PgFur protein in the A7436 strain and examined this PgFur version as a full-length protein. PgFur protein did not bind to the canonical Escherichia coli Fur box, but the wild-type phenotype of the mutant Δpgfur strain was restored partially when expression of the ecfur gene was induced from the native pgfur promoter. The full-length PgFur protein contained one zinc atom per protein monomer, but did not bind iron, manganese, or heme. Single cysteine substitutions of CXXC motifs resulted in phenotypes similar to the mutant Δpgfur strain. The modified proteins were produced in E. coli at significantly lower levels, were highly unstable, and did not bind zinc. The pgfur gene was expressed at the highest levels in bacteria cultured for 24 h in the absence of iron and heme or at higher levels in bacteria cultured for 10 h in the presence of protoporphyrin IX source. No influence of high availability of Fe2+, Zn2+, or Mn2+ on pgfur gene expression was observed. Two chromosomal mutant strains producing protein lacking 4 (pgfurΔ4aa) or 13 (pgfurΔ13aa) C-terminal amino acid residues were examined in regard to importance of the C-terminal lysine-rich region. The pgfurΔ13aa strain showed a phenotype typical for the mutant Δpgfur strain, but both the wild-type PgFur protein and its truncated version bound zinc with similar ability. The Δpgfur mutant strain produced higher amounts of HmuY protein compared with the wild-type strain, suggesting compromised regulation of its expression. Potential PgFur ligands, Fe2+, Mn2+, Zn2+, PPIX, or serum components, did not influence HmuY production in the Δpgfur mutant strain. The mutant pgfurΔ4aa and pgfurΔ13aa strains exhibited affected HmuY protein production. PgFur, regardless of the presence of the C-terminal lysine-rich region, bound to the hmu operon promoter. Our data suggest that cooperation of PgFur with partners/cofactors and/or protein/DNA modifications would be required to accomplish its role played in an in vivo multilayer regulatory network.
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Affiliation(s)
- Michał Śmiga
- Faculty of Biotechnology, University of Wrocław, Wrocław, Poland
| | - Marcin Bielecki
- Faculty of Biotechnology, University of Wrocław, Wrocław, Poland
| | - Mariusz Olczak
- Faculty of Biotechnology, University of Wrocław, Wrocław, Poland
| | - Teresa Olczak
- Faculty of Biotechnology, University of Wrocław, Wrocław, Poland
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26
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Zupok A, Iobbi-Nivol C, Méjean V, Leimkühler S. The regulation of Moco biosynthesis and molybdoenzyme gene expression by molybdenum and iron in bacteria. Metallomics 2019; 11:1602-1624. [DOI: 10.1039/c9mt00186g] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
The regulation of the operons involved in Moco biosynthesis is dependent on the availability of Fe–S clusters in the cell.
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Affiliation(s)
- Arkadiusz Zupok
- University of Potsdam
- Institute of Biochemistry and Biology
- Molecular Enzymology
- Potsdam-Golm
- Germany
| | - Chantal Iobbi-Nivol
- Aix-Marseille Université
- Institut de Microbiologie de la Méditerranée
- Laboratoire de Bioénergétique et Ingénierie des Protéines
- Centre National de la Recherche Scientifique
- Marseille
| | - Vincent Méjean
- Aix-Marseille Université
- Institut de Microbiologie de la Méditerranée
- Laboratoire de Bioénergétique et Ingénierie des Protéines
- Centre National de la Recherche Scientifique
- Marseille
| | - Silke Leimkühler
- University of Potsdam
- Institute of Biochemistry and Biology
- Molecular Enzymology
- Potsdam-Golm
- Germany
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27
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Genome-Wide Characterization of the Fur Regulatory Network Reveals a Link between Catechol Degradation and Bacillibactin Metabolism in Bacillus subtilis. mBio 2018; 9:mBio.01451-18. [PMID: 30377275 PMCID: PMC6212828 DOI: 10.1128/mbio.01451-18] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Many bacteria synthesize high-affinity iron chelators (siderophores). Siderophore-mediated iron acquisition is an efficient and widely utilized strategy for bacteria to meet their cellular iron requirements. One prominent class of siderophores uses catecholate groups to chelate iron. B. subtilis bacillibactin, structurally similar to enterobactin (made by enteric bacteria), is a triscatecholate siderophore that is hydrolyzed to monomeric units after import to release iron. However, the ultimate fates of these catechol compounds and their potential toxicities have not been defined previously. We performed genome-wide identification of Fur binding sites in vivo and uncovered a connection between catechol degradation and bacillibactin metabolism in B. subtilis. Besides its role in the detoxification of environmental catechols, the catechol 2,3-dioxygenase encoded by catDE also protects cells from intoxication by endogenous bacillibactin-derived catechol metabolites under iron-limited conditions. These findings shed light on the degradation pathway and precursor recycling of the catecholate siderophores. The ferric uptake regulator (Fur) is the global iron biosensor in many bacteria. Fur functions as an iron-dependent transcriptional repressor for most of its regulated genes. There are a few examples where holo-Fur activates transcription, either directly or indirectly. Recent studies suggest that apo-Fur might also act as a positive regulator and that, besides iron metabolism, the Fur regulon might encompass other biological processes such as DNA synthesis, energy metabolism, and biofilm formation. Here, we obtained a genomic view of the Fur regulatory network in Bacillus subtilis using chromatin immunoprecipitation sequencing (ChIP-seq). Besides the known Fur target sites, 70 putative DNA binding sites were identified, and the vast majority had higher occupancy under iron-sufficient conditions. Among the new sites detected, a Fur binding site in the promoter region of the catDE operon is of particular interest. This operon, encoding catechol 2,3-dioxygenase, is critical for catechol degradation and is under negative regulation of CatR and YodB. These three repressors (Fur, CatR, and YodB) function cooperatively to regulate the transcription of catDE, with Fur functioning as a sensor of iron limitation and CatR as the major sensor of catechol stress. Genetic analysis suggests that CatDE is involved in metabolism of the catecholate siderophore bacillibactin, particularly when bacillibactin is constitutively produced and accumulates intracellularly, potentially generating endogenous toxic catechol derivatives. This study documents a role for catechol degradation in bacillibactin metabolism and provides evidence that catechol 2,3-dioxygenase can detoxify endogenously produced catechol substrates in addition to its more widely studied role in biodegradation of environmental aromatic compounds and pollutants.
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28
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IdeR, a DtxR Family Iron Response Regulator, Controls Iron Homeostasis, Morphological Differentiation, Secondary Metabolism, and the Oxidative Stress Response in Streptomyces avermitilis. Appl Environ Microbiol 2018; 84:AEM.01503-18. [PMID: 30194099 DOI: 10.1128/aem.01503-18] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2018] [Accepted: 08/29/2018] [Indexed: 01/29/2023] Open
Abstract
Iron, an essential element for microorganisms, functions as a vital cofactor in a wide variety of key metabolic processes. On the other hand, excess iron may have toxic effects on bacteria by catalyzing the formation of reactive oxygen species through the Fenton reaction. The prevention of iron toxicity requires the precise control of intracellular iron levels in bacteria. Mechanisms of iron homeostasis in the genus Streptomyces (the producers of various antibiotics) are poorly understood. Streptomyces avermitilis is the industrial producer of avermectins, which are potent anthelmintic agents widely used in medicine, agriculture, and animal husbandry. We investigated the regulatory role of IdeR, a DtxR family regulator, in S. avermitilis In the presence of iron, IdeR binds to a specific palindromic consensus sequence in promoters and regulates 14 targets involved in iron metabolism (e.g., iron acquisition, iron storage, heme metabolism, and Fe-S assembly). IdeR also directly regulates 12 targets involved in other biological processes, including morphological differentiation, secondary metabolism, carbohydrate metabolism, and the tricarboxylic acid (TCA) cycle. ideR transcription is positively regulated by the peroxide-sensing transcriptional regulator OxyR. A newly constructed ideR deletion mutant (DideR) was found to be less responsive to iron levels and more sensitive to H2O2 treatment than the wild-type strain, indicating that ideR is essential for oxidative stress responses. Our findings, taken together, demonstrate that IdeR plays a pleiotropic role in the overall coordination of metabolism in Streptomyces spp. in response to iron levels.IMPORTANCE Iron is essential to almost all organisms, but in the presence of oxygen, iron is both poorly available and potentially toxic. Streptomyces species are predominantly present in soil where the environment is complex and fluctuating. So far, the mechanism of iron homeostasis in Streptomyces spp. remains to be elucidated. Here, we characterized the regulatory role of IdeR in the avermectin-producing organism S. avermitilis IdeR maintains intracellular iron levels by regulating genes involved in iron absorption and storage. IdeR also directly regulates morphological differentiation, secondary metabolism, and central metabolism. ideR is under the positive control of OxyR and is indispensable for an efficient response to oxidative stress. This investigation uncovered that IdeR acts as a global regulator coordinating iron homeostasis, morphological differentiation, secondary metabolism, and oxidative stress response in Streptomyces species. Elucidation of the pleiotropic regulation function of IdeR provides new insights into the mechanisms of how Streptomyces spp. adapt to the complex environment.
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29
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Rodríguez-Rodríguez S, Santos J. Detection and characterization of the ferric uptake regulator (fur) gene inPlesiomonas shigelloides. Lett Appl Microbiol 2018; 66:347-351. [DOI: 10.1111/lam.12858] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2017] [Revised: 01/18/2018] [Accepted: 01/19/2018] [Indexed: 11/27/2022]
Affiliation(s)
- S. Rodríguez-Rodríguez
- Department of Food Hygiene and Food Technology; Veterinary Faculty; University of León; Spain
| | - J.A. Santos
- Department of Food Hygiene and Food Technology; Veterinary Faculty; University of León; Spain
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30
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Sequential induction of Fur-regulated genes in response to iron limitation in Bacillus subtilis. Proc Natl Acad Sci U S A 2017; 114:12785-12790. [PMID: 29133393 DOI: 10.1073/pnas.1713008114] [Citation(s) in RCA: 60] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
Bacterial cells modulate transcription in response to changes in iron availability. The ferric uptake regulator (Fur) senses intracellular iron availability and plays a central role in maintaining iron homeostasis in Bacillus subtilis Here we utilized FrvA, a high-affinity Fe2+ efflux transporter from Listeria monocytogenes, as an inducible genetic tool to deplete intracellular iron. We then characterized the responses of the Fur, FsrA, and PerR regulons as cells transition from iron sufficiency to deficiency. Our results indicate that the Fur regulon is derepressed in three distinct waves. First, uptake systems for elemental iron (efeUOB), ferric citrate (fecCDEF), and petrobactin (fpbNOPQ) are induced to prevent iron deficiency. Second, B. subtilis synthesizes its own siderophore bacillibactin (dhbACEBF) and turns on bacillibactin (feuABC) and hydroxamate siderophore (fhuBCGD) uptake systems to scavenge iron from the environment and flavodoxins (ykuNOP) to replace ferredoxins. Third, as iron levels decline further, an "iron-sparing" response (fsrA, fbpAB, and fbpC) is induced to block the translation of abundant iron-utilizing proteins and thereby permit the most essential iron-dependent enzymes access to the limited iron pools. ChIP experiments demonstrate that in vivo occupancy of Fur correlates with derepression of each operon, and the graded response observed here results, at least in part, from higher-affinity binding of Fur to the "late"-induced genes.
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Abstract
Neisseria meningitidis is a harmless commensal bacterium finely adapted to humans. Unfortunately, under “privileged” conditions, it adopts a “devious” lifestyle leading to uncontrolled behavior characterized by the unleashing of molecular weapons causing potentially lethal disease such as sepsis and acute meningitis. Indeed, despite the lack of a classic repertoire of virulence genes in
N. meningitidis separating commensal from invasive strains, molecular epidemiology and functional genomics studies suggest that carriage and invasive strains belong to genetically distinct populations characterized by an exclusive pathogenic potential. In the last few years, “omics” technologies have helped scientists to unwrap the framework drawn by
N. meningitidis during different stages of colonization and disease. However, this scenario is still incomplete and would benefit from the implementation of physiological tissue models for the reproduction of mucosal and systemic interactions
in vitro. These emerging technologies supported by recent advances in the world of stem cell biology hold the promise for a further understanding of
N. meningitidis pathogenesis.
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Abstract
Bacteria require iron for growth, with only a few reported exceptions. In many environments, iron is a limiting nutrient for growth and high affinity uptake systems play a central role in iron homeostasis. However, iron can also be detrimental to cells when it is present in excess, particularly under aerobic conditions where its participation in Fenton chemistry generates highly reactive hydroxyl radicals. Recent results have revealed a critical role for iron efflux transporters in protecting bacteria from iron intoxication. Systems that efflux iron are widely distributed amongst bacteria and fall into several categories: P1B-type ATPases, cation diffusion facilitator (CDF) proteins, major facilitator superfamily (MFS) proteins, and membrane bound ferritin-like proteins. Here, we review the emerging role of iron export in both iron homeostasis and as part of the adaptive response to oxidative stress.
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Affiliation(s)
- Hualiang Pi
- Department of Microbiology, Cornell University, Ithaca, NY 14853-8101, USA.
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33
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Choi SH, Lee KL, Shin JH, Cho YB, Cha SS, Roe JH. Zinc-dependent regulation of zinc import and export genes by Zur. Nat Commun 2017; 8:15812. [PMID: 28598435 PMCID: PMC5472717 DOI: 10.1038/ncomms15812] [Citation(s) in RCA: 56] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2016] [Accepted: 05/04/2017] [Indexed: 12/21/2022] Open
Abstract
In most bacteria, zinc depletion is sensed by Zur, whereas the surplus is sensed by different regulators to achieve zinc homeostasis. Here we present evidence that zinc-bound Zur not only represses genes for zinc acquisition but also induces the zitB gene encoding a zinc exporter in Streptomyces coelicolor, a model actinobacteria. Zinc-dependent gene regulation by Zur occurs in two phases. At sub-femtomolar zinc concentrations (phase I), dimeric Zur binds to the Zur-box motif immediately upstream of the zitB promoter, resulting in low zitB expression. At the same time, Zur represses genes for zinc uptake. At micromolar zinc concentrations (phase II), oligomeric Zur binding with footprint expansion upward from the Zur box results in high zitB induction. Our findings reveal a mode of zinc-dependent gene activation that uses a single metalloregulator to control genes for both uptake and export over a wide range of zinc concentrations. Zinc homeostasis in most bacteria is achieved by a set of regulators, each responding to a certain level of intracellular zinc. Here the authors show that, in Streptomyces coelicolor, the Zur regulator modulates the expression of genes for zinc import and export over a large range of zinc concentrations.
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Affiliation(s)
- Seung-Hwan Choi
- Laboratory of Molecular Microbiology, School of Biological Sciences, and Institute of Microbiology, Seoul National University, Seoul 151-742, Korea
| | - Kang-Lok Lee
- Laboratory of Molecular Microbiology, School of Biological Sciences, and Institute of Microbiology, Seoul National University, Seoul 151-742, Korea
| | - Jung-Ho Shin
- Laboratory of Molecular Microbiology, School of Biological Sciences, and Institute of Microbiology, Seoul National University, Seoul 151-742, Korea
| | - Yoo-Bok Cho
- Laboratory of Molecular Microbiology, School of Biological Sciences, and Institute of Microbiology, Seoul National University, Seoul 151-742, Korea
| | - Sun-Shin Cha
- Department of Chemistry and Nano Science, Ewha Womans University, Seoul 03760, Republic of Korea
| | - Jung-Hye Roe
- Laboratory of Molecular Microbiology, School of Biological Sciences, and Institute of Microbiology, Seoul National University, Seoul 151-742, Korea
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Pakarian P, Pawelek PD. A novel set of vectors for Fur-controlled protein expression under iron deprivation in Escherichia coli. BMC Biotechnol 2016; 16:68. [PMID: 27619907 PMCID: PMC5020551 DOI: 10.1186/s12896-016-0298-1] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2016] [Accepted: 09/06/2016] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND In the presence of sufficient iron, the Escherichia coli protein Fur (Ferric Uptake Regulator) represses genes controlled by the Fur box, a consensus sequence near or within promoters of target genes. De-repression of Fur-controlled genes occurs upon iron deprivation. In the E. coli chromosome, there is a bidirectional intercistronic promoter region with two non-overlapping Fur boxes. This region controls Fur-regulated expression of entCEBAH in the clockwise direction and fepB in the anticlockwise direction. RESULTS We cloned the E. coli bidirectional fepB/entC promoter region into low-copy-number plasmid backbones (pACYC184 and pBR322) along with downstream sequences encoding epitope tags and a multiple cloning site (MCS) compatible with the bacterial adenylate cyclase two-hybrid (BACTH) system. The vector pFCF1 allows for iron-controlled expression of FLAG-tagged proteins, whereas the pFBH1 vector allows for iron-controlled expression of HA-tagged proteins. We showed that E. coli knockout strains transformed with pFCF1-entA, pFCF1-entE and pFBH1-entB express corresponding proteins with appropriate epitope tags when grown under iron restriction. Furthermore, transformants exhibited positive chrome azurol S (CAS) assay signals under iron deprivation, indicating that the transformants were functional for siderophore biosynthesis. Western blotting and growth studies in rich and iron-depleted media demonstrated that protein expression from these plasmids was under iron control. Finally, we produced the vector pFCF2, a pFCF1 derivative in which a kanamycin resistance (KanR) gene was engineered in the direction opposite of the MCS. The entA ORF was then subcloned into the pFCF2 MCS. Bidirectional protein expression in an iron-deprived pFCF2-entA transformant was confirmed using antibiotic selection, CAS assays and growth studies. CONCLUSIONS The vectors pFCF1, pFCF2, and pFBH1 have been shown to use the fepB/entC promoter region to control bidirectional in trans expression of epitope-tagged proteins in iron-depleted transformants. In the presence of intracellular iron, protein expression from these constructs was abrogated due to Fur repression. The compatibility of the pFCF1 and pFBH1 backbones allows for iron-controlled expression of multiple epitope-tagged proteins from a single co-transformant.
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Affiliation(s)
- Paknoosh Pakarian
- Department of Chemistry and Biochemistry, Concordia University, 7141 Sherbrooke St., W., Montreal, QC, H4B 1R6, Canada
| | - Peter D Pawelek
- Department of Chemistry and Biochemistry, Concordia University, 7141 Sherbrooke St., W., Montreal, QC, H4B 1R6, Canada. .,Groupe de Recherche Axé sur la Structure des Protéines (GRASP), Montreal, Canada.
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Expanding the Role of FurA as Essential Global Regulator in Cyanobacteria. PLoS One 2016; 11:e0151384. [PMID: 26967347 PMCID: PMC4788461 DOI: 10.1371/journal.pone.0151384] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2015] [Accepted: 02/26/2016] [Indexed: 01/03/2023] Open
Abstract
In the nitrogen-fixing heterocyst-forming cyanobacterium Anabaena sp. PCC 7120, the ferric uptake regulator FurA plays a global regulatory role. Failures to eliminate wild-type copies of furA gene from the polyploid genome suggest essential functions. In the present study, we developed a selectively regulated furA expression system by the replacement of furA promoter in the Anabaena sp. chromosomes with the Co2+/Zn2+ inducible coaT promoter from Synechocystis sp. PCC 6803. By removing Co2+ and Zn2+ from the medium and shutting off furA expression, we showed that FurA was absolutely required for cyanobacterial growth. RNA-seq based comparative transcriptome analyses of the furA-turning off strain and its parental wild-type in conjunction with subsequent electrophoretic mobility shift assays and semi-quantitative RT-PCR were carried out in order to identify direct transcriptional targets and unravel new biological roles of FurA. The results of such approaches led us to identify 15 novel direct iron-dependent transcriptional targets belonging to different functional categories including detoxification and defences against oxidative stress, phycobilisome degradation, chlorophyll catabolism and programmed cell death, light sensing and response, heterocyst differentiation, exopolysaccharide biosynthesis, among others. Our analyses evidence novel interactions in the complex regulatory network orchestrated by FurA in cyanobacteria.
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Gasparini R, Panatto D, Bragazzi NL, Lai PL, Bechini A, Levi M, Durando P, Amicizia D. How the Knowledge of Interactions between Meningococcus and the Human Immune System Has Been Used to Prepare Effective Neisseria meningitidis Vaccines. J Immunol Res 2015; 2015:189153. [PMID: 26351643 PMCID: PMC4553322 DOI: 10.1155/2015/189153] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2015] [Accepted: 06/09/2015] [Indexed: 01/17/2023] Open
Abstract
In the last decades, tremendous advancement in dissecting the mechanisms of pathogenicity of Neisseria meningitidis at a molecular level has been achieved, exploiting converging approaches of different disciplines, ranging from pathology to microbiology, immunology, and omics sciences (such as genomics and proteomics). Here, we review the molecular biology of the infectious agent and, in particular, its interactions with the immune system, focusing on both the innate and the adaptive responses. Meningococci exploit different mechanisms and complex machineries in order to subvert the immune system and to avoid being killed. Capsular polysaccharide and lipooligosaccharide glycan composition, in particular, play a major role in circumventing immune response. The understanding of these mechanisms has opened new horizons in the field of vaccinology. Nowadays different licensed meningococcal vaccines are available and used: conjugate meningococcal C vaccines, tetravalent conjugate vaccines, an affordable conjugate vaccine against the N. menigitidis serogroup A, and universal vaccines based on multiple antigens each one with a different and peculiar function against meningococcal group B strains.
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Affiliation(s)
- R. Gasparini
- Department of Health Sciences, University of Genoa, Via Pastore 1, 16132 Genoa, Italy
| | - D. Panatto
- Department of Health Sciences, University of Genoa, Via Pastore 1, 16132 Genoa, Italy
| | - N. L. Bragazzi
- Department of Health Sciences, University of Genoa, Via Pastore 1, 16132 Genoa, Italy
| | - P. L. Lai
- Department of Health Sciences, University of Genoa, Via Pastore 1, 16132 Genoa, Italy
| | - A. Bechini
- Department of Health Sciences, University of Florence, Viale G.B. Morgagni 48, 50134 Florence, Italy
| | - M. Levi
- Department of Health Sciences, University of Florence, Viale G.B. Morgagni 48, 50134 Florence, Italy
| | - P. Durando
- Department of Health Sciences, University of Genoa, Via Pastore 1, 16132 Genoa, Italy
| | - D. Amicizia
- Department of Health Sciences, University of Genoa, Via Pastore 1, 16132 Genoa, Italy
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Kaushik MS, Singh P, Tiwari B, Mishra AK. Ferric Uptake Regulator (FUR) protein: properties and implications in cyanobacteria. ANN MICROBIOL 2015. [DOI: 10.1007/s13213-015-1134-x] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
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Fernandez-López R, Ruiz R, de la Cruz F, Moncalián G. Transcription factor-based biosensors enlightened by the analyte. Front Microbiol 2015; 6:648. [PMID: 26191047 PMCID: PMC4486848 DOI: 10.3389/fmicb.2015.00648] [Citation(s) in RCA: 88] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2015] [Accepted: 06/15/2015] [Indexed: 01/17/2023] Open
Abstract
Whole cell biosensors (WCBs) have multiple applications for environmental monitoring, detecting a wide range of pollutants. WCBs depend critically on the sensitivity and specificity of the transcription factor (TF) used to detect the analyte. We describe the mechanism of regulation and the structural and biochemical properties of TF families that are used, or could be used, for the development of environmental WCBs. Focusing on the chemical nature of the analyte, we review TFs that respond to aromatic compounds (XylS-AraC, XylR-NtrC, and LysR), metal ions (MerR, ArsR, DtxR, Fur, and NikR) or antibiotics (TetR and MarR). Analyzing the structural domains involved in DNA recognition, we highlight the similitudes in the DNA binding domains (DBDs) of these TF families. Opposite to DBDs, the wide range of analytes detected by TFs results in a diversity of structures at the effector binding domain. The modular architecture of TFs opens the possibility of engineering TFs with hybrid DNA and effector specificities. Yet, the lack of a crisp correlation between structural domains and specific functions makes this a challenging task.
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Affiliation(s)
| | | | | | - Gabriel Moncalián
- Departamento de Biología Molecular and Instituto de Biomedicina y Biotecnología de Cantabria, Universidad de Cantabria – Consejo Superior de Investigaciones CientíficasSantander, Spain
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Abstract
The exclusive reservoir of the genus Neisseria is the human. Of the broad range of species that comprise the Neisseria, only two are frequently pathogenic, and only one of those is a resident of the nasopharynx. Although Neisseria meningitidis can cause severe disease if it invades the bloodstream, the vast majority of interactions between humans and Neisseria are benign, with the bacteria inhabiting its mucosal niche as a non-invasive commensal. Understandably, with the exception of Neisseria gonorrhoeae, which preferentially colonises the urogenital tract, the neisseriae are extremely well adapted to survival in the human nasopharynx, their sole biological niche. The purpose of this review is to provide an overview of the molecular mechanisms evolved by Neisseria to facilitate colonisation and survival within the nasopharynx, focussing on N. meningitidis. The organism has adapted to survive in aerosolised transmission and to attach to mucosal surfaces. It then has to replicate in a nutrition-poor environment and resist immune and competitive pressure within a polymicrobial complex. Temperature and relative gas concentrations (nitric oxide and oxygen) are likely to be potent initial signals of arrival within the nasopharyngeal environment, and this review will focus on how N. meningitidis responds to these to increase the likelihood of its survival.
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Seo SW, Kim D, Latif H, O'Brien EJ, Szubin R, Palsson BO. Deciphering Fur transcriptional regulatory network highlights its complex role beyond iron metabolism in Escherichia coli. Nat Commun 2014; 5:4910. [PMID: 25222563 PMCID: PMC4167408 DOI: 10.1038/ncomms5910] [Citation(s) in RCA: 190] [Impact Index Per Article: 19.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2014] [Accepted: 08/05/2014] [Indexed: 02/07/2023] Open
Abstract
The ferric uptake regulator (Fur) plays a critical role in the transcriptional regulation of iron metabolism. However, the full regulatory potential of Fur remains undefined. Here we comprehensively reconstruct the Fur transcriptional regulatory network in Escherichia coli K-12 MG1655 in response to iron availability using genome-wide measurements (ChIP-exo and RNA-seq). Integrative data analysis reveals that a total of 81 genes in 42 transcription units are directly regulated by three different modes of Fur regulation, including apo- and holo-Fur activation and holo-Fur repression. We show that Fur connects iron transport and utilization enzymes with negative-feedback loop pairs for iron homeostasis. In addition, direct involvement of Fur in the regulation of DNA synthesis, energy metabolism, and biofilm development is found. These results show how Fur exhibits a comprehensive regulatory role affecting many fundamental cellular processes linked to iron metabolism in order to coordinate the overall response of E. coli to iron availability.
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Affiliation(s)
- Sang Woo Seo
- 1] Department of Bioengineering, University of California San Diego, La Jolla, California 92093-0412, USA [2]
| | - Donghyuk Kim
- 1] Department of Bioengineering, University of California San Diego, La Jolla, California 92093-0412, USA [2]
| | - Haythem Latif
- 1] Department of Bioengineering, University of California San Diego, La Jolla, California 92093-0412, USA [2]
| | - Edward J O'Brien
- Department of Bioengineering, University of California San Diego, La Jolla, California 92093-0412, USA
| | - Richard Szubin
- Department of Bioengineering, University of California San Diego, La Jolla, California 92093-0412, USA
| | - Bernhard O Palsson
- 1] Department of Bioengineering, University of California San Diego, La Jolla, California 92093-0412, USA [2] Novo Nordisk Foundation Center for Biosustainability, Technical University of Denmark, 2800 Lyngby, Denmark
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HrrF is the Fur-regulated small RNA in nontypeable Haemophilus influenzae. PLoS One 2014; 9:e105644. [PMID: 25157846 PMCID: PMC4144887 DOI: 10.1371/journal.pone.0105644] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2014] [Accepted: 07/21/2014] [Indexed: 02/06/2023] Open
Abstract
Nontypeable Haemophilus influenzae (NTHi) are Gram-negative commensal bacteria that reside in the nasopharynx. NTHi can also cause multiple upper and lower respiratory tract diseases that include sinusitis, conjunctivitis, bronchitis, and otitis media. In numerous bacterial species the ferric uptake regulator (Fur) acts as a global regulator of iron homeostasis by negatively regulating the expression of iron uptake systems. However in NTHi strain 86-028NP and numerous other bacterial species there are multiple instances where Fur positively affects gene expression. It is known that many instances of positive regulation by Fur occur indirectly through a small RNA intermediate. However, no examples of small RNAs have been described in NTHi. Therefore we used RNA-Seq analysis to analyze the transcriptome of NTHi strain 86-028NPrpsL and an isogenic 86-028NPrpsLΔfur strain to identify Fur-regulated intergenic transcripts. From this analysis we identified HrrF, the first small RNA described in any Haemophilus species. Orthologues of this small RNA exist only among other Pasteurellaceae. Our analysis showed that HrrF is maximally expressed when iron levels are low. Additionally, Fur was shown to bind upstream of the hrrF promoter. RNA-Seq analysis was used to identify targets of HrrF which include genes whose products are involved in molybdate uptake, deoxyribonucleotide synthesis, and amino acid biosynthesis. The stability of HrrF is not dependent on the RNA chaperone Hfq. This study is the first step in an effort to investigate the role small RNAs play in altering gene expression in response to iron limitation in NTHi.
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Yu C, Lopez CA, Hu H, Xia Y, Freedman DS, Reddington AP, Daaboul GG, Ünlü MS, Genco CA. A high-throughput method to examine protein-nucleotide interactions identifies targets of the bacterial transcriptional regulatory protein fur. PLoS One 2014; 9:e96832. [PMID: 24811061 PMCID: PMC4014563 DOI: 10.1371/journal.pone.0096832] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2014] [Accepted: 04/13/2014] [Indexed: 11/19/2022] Open
Abstract
The Ferric uptake regulatory protein (Fur) is a transcriptional regulatory protein that functions to control gene transcription in response to iron in a number of pathogenic bacteria. In this study, we applied a label-free, quantitative and high-throughput analysis method, Interferometric Reflectance Imaging Sensor (IRIS), to rapidly characterize Fur-DNA interactions in vitro with predicted Fur binding sequences in the genome of Neisseria gonorrhoeae, the causative agent of the sexually transmitted disease gonorrhea. IRIS can easily be applied to examine multiple protein-protein, protein-nucleotide and nucleotide-nucleotide complexes simultaneously and demonstrated here that seventy percent of the predicted Fur boxes in promoter regions of iron-induced genes bound to Fur in vitro with a range of affinities as observed using this microarray screening technology. Combining binding data with mRNA expression levels in a gonococcal fur mutant strain allowed us to identify five new gonococcal genes under Fur-mediated direct regulation.
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Affiliation(s)
- Chunxiao Yu
- Department of Medicine, Section of Infectious Diseases, Boston University School of Medicine, Boston University, Boston, Massachusetts, United States of America
| | - Carlos A. Lopez
- Department of Electrical and Computer Engineering, Boston University, Boston, Massachusetts, United States of America
| | - Han Hu
- Bioinformatics Graduate Program, Boston University, Boston, Massachusetts, United States of America
| | - Yu Xia
- Bioinformatics Graduate Program, Boston University, Boston, Massachusetts, United States of America
| | - David S. Freedman
- Department of Biomedical Engineering, Boston University, Boston, Massachusetts, United States of America
| | - Alexander P. Reddington
- Department of Electrical and Computer Engineering, Boston University, Boston, Massachusetts, United States of America
| | - George G. Daaboul
- Department of Biomedical Engineering, Boston University, Boston, Massachusetts, United States of America
| | - M. Selim Ünlü
- Department of Electrical and Computer Engineering, Boston University, Boston, Massachusetts, United States of America
- Department of Biomedical Engineering, Boston University, Boston, Massachusetts, United States of America
- Physics Department, Boston University, Boston, Massachusetts, United States of America
| | - Caroline Attardo Genco
- Department of Medicine, Section of Infectious Diseases, Boston University School of Medicine, Boston University, Boston, Massachusetts, United States of America
- Department of Microbiology, Boston University School of Medicine, Boston University, Boston, Massachusetts, United States of America
- * E-mail:
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The iron stimulon and fur regulon of Geobacter sulfurreducens and their role in energy metabolism. Appl Environ Microbiol 2014; 80:2918-27. [PMID: 24584254 DOI: 10.1128/aem.03916-13] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Iron plays a critical role in the physiology of Geobacter species. It serves as both an essential component for proteins and cofactors and an electron acceptor during anaerobic respiration. Here, we investigated the iron stimulon and ferric uptake regulator (Fur) regulon of Geobacter sulfurreducens to examine the coordination between uptake of Fe(II) and the reduction of Fe(III) at the transcriptional level. Gene expression studies across a variety of different iron concentrations in both the wild type and a Δfur mutant strain were used to determine the iron stimulon. The stimulon consists of a broad range of gene products, ranging from iron-utilizing to central metabolism and iron reduction proteins. Integration of gene expression and chromatin immunoprecipitation (ChIP) data sets assisted in the identification of the Fur transcriptional regulatory network and Fur's role as a regulator of the iron stimulon. Additional physiological and transcriptional analyses of G. sulfurreducens grown with various Fe(II) concentrations revealed the depth of Fur's involvement in energy metabolism and the existence of redundancy within the iron-regulatory network represented by IdeR, an alternative iron transcriptional regulator. These characteristics enable G. sulfurreducens to thrive in environments with fluctuating iron concentrations by providing it with a robust mechanism to maintain tight and deliberate control over intracellular iron homeostasis.
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Yang XW, He Y, Xu J, Xiao X, Wang FP. The regulatory role of ferric uptake regulator (Fur) during anaerobic respiration of Shewanella piezotolerans WP3. PLoS One 2013; 8:e75588. [PMID: 24124499 PMCID: PMC3790847 DOI: 10.1371/journal.pone.0075588] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2013] [Accepted: 08/16/2013] [Indexed: 12/02/2022] Open
Abstract
Ferric uptake regulator (Fur) is a global regulator that controls bacterial iron homeostasis. In this study, a fur deletion mutant of the deep-sea bacterium Shewanella piezotolerans WP3 was constructed. Physiological studies revealed that the growth rate of this mutant under aerobic conditions was only slightly lower than that of wild type (WT), but severe growth defects were observed under anaerobic conditions when different electron acceptors (EAs) were provided. Comparative transcriptomic analysis demonstrated that Fur is involved not only in classical iron homeostasis but also in anaerobic respiration. Fur exerted pleiotropic effects on the regulation of anaerobic respiration by controlling anaerobic electron transport, the heme biosynthesis system, and the cytochrome c maturation system. Biochemical assays demonstrated that levels of c-type cytochromes were lower in the fur mutant, consistent with the transcriptional profiling. Transcriptomic analysis and electrophoretic mobility shift assays revealed a primary regulation network for Fur in WP3. These results suggest that Fur may act as a sensor for anoxic conditions to trigger and influence the anaerobic respiratory system.
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Affiliation(s)
- Xin-Wei Yang
- State Key Laboratory of Microbial Metabolism and School of Life Sciences and Biotechnology, State Key Laboratory of Ocean Engineering, Shanghai Jiao Tong University, Shanghai, PR China
| | - Ying He
- State Key Laboratory of Microbial Metabolism and School of Life Sciences and Biotechnology, State Key Laboratory of Ocean Engineering, Shanghai Jiao Tong University, Shanghai, PR China
| | - Jun Xu
- State Key Laboratory of Microbial Metabolism and School of Life Sciences and Biotechnology, State Key Laboratory of Ocean Engineering, Shanghai Jiao Tong University, Shanghai, PR China
| | - Xiang Xiao
- State Key Laboratory of Microbial Metabolism and School of Life Sciences and Biotechnology, State Key Laboratory of Ocean Engineering, Shanghai Jiao Tong University, Shanghai, PR China
| | - Feng-Ping Wang
- State Key Laboratory of Microbial Metabolism and School of Life Sciences and Biotechnology, State Key Laboratory of Ocean Engineering, Shanghai Jiao Tong University, Shanghai, PR China
- Key Laboratory of Systems Biomedicine, Ministry of Education, Shanghai Jiao Tong University, Shanghai, PR China
- * E-mail:
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Troxell B, Hassan HM. Transcriptional regulation by Ferric Uptake Regulator (Fur) in pathogenic bacteria. Front Cell Infect Microbiol 2013; 3:59. [PMID: 24106689 PMCID: PMC3788343 DOI: 10.3389/fcimb.2013.00059] [Citation(s) in RCA: 298] [Impact Index Per Article: 27.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2013] [Accepted: 09/18/2013] [Indexed: 12/16/2022] Open
Abstract
In the ancient anaerobic environment, ferrous iron (Fe2+) was one of the first metal cofactors. Oxygenation of the ancient world challenged bacteria to acquire the insoluble ferric iron (Fe3+) and later to defend against reactive oxygen species (ROS) generated by the Fenton chemistry. To acquire Fe3+, bacteria produce low-molecular weight compounds, known as siderophores, which have extremely high affinity for Fe3+. However, during infection the host restricts iron from pathogens by producing iron- and siderophore-chelating proteins, by exporting iron from intracellular pathogen-containing compartments, and by limiting absorption of dietary iron. Ferric Uptake Regulator (Fur) is a transcription factor which utilizes Fe2+ as a corepressor and represses siderophore synthesis in pathogens. Fur, directly or indirectly, controls expression of enzymes that protect against ROS damage. Thus, the challenges of iron homeostasis and defense against ROS are addressed via Fur. Although the role of Fur as a repressor is well-documented, emerging evidence demonstrates that Fur can function as an activator. Fur activation can occur through three distinct mechanisms (1) indirectly via small RNAs, (2) binding at cis regulatory elements that enhance recruitment of the RNA polymerase holoenzyme (RNAP), and (3) functioning as an antirepressor by removing or blocking DNA binding of a repressor of transcription. In addition, Fur homologs control defense against peroxide stress (PerR) and control uptake of other metals such as zinc (Zur) and manganese (Mur) in pathogenic bacteria. Fur family members are important for virulence within bacterial pathogens since mutants of fur, perR, or zur exhibit reduced virulence within numerous animal and plant models of infection. This review focuses on the breadth of Fur regulation in pathogenic bacteria.
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Affiliation(s)
- Bryan Troxell
- Department of Immunology and Microbiology, Indiana University School of Medicine Indianapolis, IN, USA
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Oglesby-Sherrouse AG, Murphy ER. Iron-responsive bacterial small RNAs: variations on a theme. Metallomics 2013; 5:276-86. [PMID: 23340911 DOI: 10.1039/c3mt20224k] [Citation(s) in RCA: 77] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
For most living organisms, iron is both essential and potentially toxic, making the precise maintenance of iron homeostasis necessary for survival. To manage this paradox, bacteria regulate the acquisition, utilization, and storage of iron in response to its availability. The iron-dependent ferric uptake repressor (Fur) often mediates this iron-responsive regulation by both direct and indirect mechanisms. In 2002, Masse and Gottesman identified a novel target of Fur-mediated regulation in Escherichia coli: a gene encoding a small regulatory RNA (sRNA) termed RyhB. Under conditions of iron-limitation, RyhB is produced and functions to regulate the expression of several target genes encoding iron-utilizing enzymes, iron acquisition systems, and iron storage factors. This pivotal finding provided the missing link between environmental iron-limitation and previously observed decreases in certain iron-dependent metabolic pathways, a phenomenon now referred to as an "iron-sparing" response. The discovery of RyhB opened the door to the rapidly expanding field of bacterial iron-regulated sRNAs, which continue to be identified and described in numerous bacterial species. Most striking are findings that the impact of iron-responsive sRNA regulation often extends beyond iron homeostasis, particularly with regard to production of virulence-associated factors by pathogenic bacteria. This review discusses trends in the collective body of work on iron-regulated sRNAs, highlighting both the regulatory mechanisms they utilize to control target gene expression and the impact of this regulation on basic processes controlling bacterial physiology and virulence.
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Affiliation(s)
- Amanda G Oglesby-Sherrouse
- Department of Pharmaceutical Sciences, School of Pharmacy, Department of Microbiology and Immunology, School of Medicine, University of Maryland Baltimore, 20 Penn Street, Baltimore, MD, USA.
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Control of RNA stability by NrrF, an iron-regulated small RNA in Neisseria gonorrhoeae. J Bacteriol 2013; 195:5166-73. [PMID: 24039262 DOI: 10.1128/jb.00839-13] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
Regulation of gene expression by small noncoding RNAs (sRNAs) plays a critical role in bacterial response to physiological stresses. NrrF, a trans-acting sRNA in Neisseria meningitidis and Neisseria gonorrhoeae, has been shown in the meningococcus to control indirectly, in response to iron (Fe) availability, the transcription of genes encoding subunits of succinate dehydrogenase, a Fe-requiring enzyme. Given that in other organisms, sRNAs target multiple mRNAs to control gene expression, we used a global approach to examine the role of NrrF in controlling gonococcal transcription. Three strains, including N. gonorrhoeae FA1090, an nrrF deletion mutant, and a complemented derivative, were examined using a custom CombiMatrix microarray to assess the role of this sRNA in controlling gene expression in response to Fe availability. In the absence of NrrF, the mRNA half-lives for 12 genes under Fe-depleted growth conditions were longer than those in FA1090. The 12 genes controlled by NrrF encoded proteins with biological functions including energy metabolism, oxidative stress, antibiotic resistance, and amino acid synthesis, as well as hypothetical proteins and a regulatory protein whose functions are not fully understood.
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da Silva Neto JF, Lourenço RF, Marques MV. Global transcriptional response of Caulobacter crescentus to iron availability. BMC Genomics 2013; 14:549. [PMID: 23941329 PMCID: PMC3751524 DOI: 10.1186/1471-2164-14-549] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2013] [Accepted: 08/09/2013] [Indexed: 01/22/2023] Open
Abstract
Background In the alpha subclass of proteobacteria iron homeostasis is controlled by diverse iron responsive regulators. Caulobacter crescentus, an important freshwater α-proteobacterium, uses the ferric uptake repressor (Fur) for such purpose. However, the impact of the iron availability on the C. crescentus transcriptome and an overall perspective of the regulatory networks involved remain unknown. Results In this work we report the identification of iron-responsive and Fur-regulated genes in C. crescentus using microarray-based global transcriptional analyses. We identified 42 genes that were strongly upregulated both by mutation of fur and by iron limitation condition. Among them, there are genes involved in iron uptake (four TonB-dependent receptor gene clusters, and feoAB), riboflavin biosynthesis and genes encoding hypothetical proteins. Most of these genes are associated with predicted Fur binding sites, implicating them as direct targets of Fur-mediated repression. These data were validated by β-galactosidase and EMSA assays for two operons encoding putative transporters. The role of Fur as a positive regulator is also evident, given that 27 genes were downregulated both by mutation of fur and under low-iron condition. As expected, this group includes many genes involved in energy metabolism, mostly iron-using enzymes. Surprisingly, included in this group are also TonB-dependent receptors genes and the genes fixK, fixT and ftrB encoding an oxygen signaling network required for growth during hypoxia. Bioinformatics analyses suggest that positive regulation by Fur is mainly indirect. In addition to the Fur modulon, iron limitation altered expression of 113 more genes, including induction of genes involved in Fe-S cluster assembly, oxidative stress and heat shock response, as well as repression of genes implicated in amino acid metabolism, chemotaxis and motility. Conclusions Using a global transcriptional approach, we determined the C. crescentus iron stimulon. Many but not all of iron responsive genes were directly or indirectly controlled by Fur. The iron limitation stimulon overlaps with other regulatory systems, such as the RpoH and FixK regulons. Altogether, our results showed that adaptation of C. crescentus to iron limitation not only involves increasing the transcription of iron-acquisition systems and decreasing the production of iron-using proteins, but also includes novel genes and regulatory mechanisms.
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Affiliation(s)
- José F da Silva Neto
- Departamento de Microbiologia, Instituto de Ciências Biomédicas, Universidade de São Paulo, Av Prof Lineu Prestes 1374, 05508-000 São Paulo, Brazil.
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Gilbreath JJ, Pich OQ, Benoit SL, Besold AN, Cha JH, Maier RJ, Michel SLJ, Maynard EL, Merrell DS. Random and site-specific mutagenesis of the Helicobacter pylori ferric uptake regulator provides insight into Fur structure-function relationships. Mol Microbiol 2013; 89:304-23. [PMID: 23710935 DOI: 10.1111/mmi.12278] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/22/2013] [Indexed: 12/29/2022]
Abstract
The ferric uptake regulator (Fur) of Helicobacter pylori is a global regulator that is important for colonization and survival within the gastric mucosa. H. pylori Fur is unique in its ability to activate and repress gene expression in both the iron-bound (Fe-Fur) and apo forms (apo-Fur). In the current study we combined random and site-specific mutagenesis to identify amino acid residues important for both Fe-Fur and apo-Fur function. We identified 25 mutations that affected Fe-Fur repression and 23 mutations that affected apo-Fur repression, as determined by transcriptional analyses of the Fe-Fur target gene amiE, and the apo-Fur target gene, pfr. In addition, eight of these mutations also significantly affected levels of Fur in the cell. Based on regulatory phenotypes, we selected several representative mutations to characterize further. Of those selected, we purified the wild-type (HpFurWT) and three mutant Fur proteins (HpFurE5A, HpFurA92T and HpFurH134Y), which represent mutations in the N-terminal extension, the regulatory metal binding site (S2) and the structural metal binding site (S3) respectively. Purified proteins were evaluated for secondary structure by circular dichroism spectroscopy, iron-binding by atomic absorption spectrophotometry, oligomerization in manganese-substituted and apo conditions by in vitro cross-linking assays, and DNA binding to Fe-Fur and apo-Fur target sequences by fluorescence anisotropy. The results showed that the N-terminal, S2 and S3 regions play distinct roles in terms of Fur structure-function relationships. Overall, these studies provide novel information regarding the role of these residues in Fur function, and provide mechanistic insight into how H. pylori Fur regulates gene expression in both the iron-bound and apo forms of the protein.
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Affiliation(s)
- Jeremy J Gilbreath
- Department of Microbiology and Immunology, Uniformed Services University of Health Sciences, Bethesda, MD, USA
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Del Tordello E, Serruto D. Functional genomics studies of the human pathogen Neisseria meningitidis. Brief Funct Genomics 2013; 12:328-40. [PMID: 23723380 DOI: 10.1093/bfgp/elt018] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Neisseria meningitidis is a strictly human pathogen and is one of the major causes of septicemia and meningitis worldwide. Functional genomics approaches have been extensively applied to study how N. meningitidis adapts to grow and survive in different human niches encountered during the infection. DNA microarrays performed in in vitro and ex vivo conditions have revealed changes in the transcriptome profiles of N. meningitidis upon interaction with human cells and after incubation in human serum and blood. Mutagenesis studies allowed detecting mutants in genes crucial for N. meningitidis colonization and systemic infection. The analysis of N. meningitidis genomes has been also successful in the identification of vaccine candidates used to develop an effective protein-based vaccine. The application of all these approaches revealed the potential to identify new virulence factors and vaccine candidates and to assign functions to previously uncharacterized genes providing new insights in the biology and pathogenesis of N. meningitidis.
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