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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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2
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A Positively Selected fur-R88H Mutation Enhances Helicobacter pylori Fitness in a High-Salt Environment and Alters Fur-Dependent Regulation of Gene Expression. Infect Immun 2023; 91:e0042022. [PMID: 36633416 PMCID: PMC9933627 DOI: 10.1128/iai.00420-22] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023] Open
Abstract
Both Helicobacter pylori infection and a high-salt diet are risk factors for gastric cancer. We previously showed that a mutation in fur (encoding the ferric uptake regulator variant Fur-R88H) was positively selected in H. pylori strains isolated from experimentally infected Mongolian gerbils receiving a high-salt diet. In the present study, we report that continuous H. pylori growth in high-salt conditions in vitro also leads to positive selection of the fur-R88H mutation. Competition experiments with strains containing wild-type fur or fur-R88H, each labeled with unique nucleotide barcodes, showed that the fur-R88H mutation enhances H. pylori fitness under high-salt conditions but reduces H. pylori fitness under routine culture conditions. The fitness advantage of the fur-R88H mutant under high-salt conditions was abrogated by the addition of supplemental iron. To test the hypothesis that the fur-R88H mutation alters the regulatory properties of Fur, we compared the transcriptional profiles of strains containing wild-type fur or fur-R88H. Increased transcript levels of fecA2, which encodes a predicted TonB-dependent outer membrane transporter, were detected in the fur-R88H variant compared to those in the strain containing wild-type fur under both high-salt and routine conditions. Competition experiments showed that fecA2 contributes to H. pylori fitness under both high-salt and routine conditions. These results provide new insights into mechanisms by which the fur-R88H mutation confers a selective advantage to H. pylori in high-salt environments.
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3
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Insights into the Orchestration of Gene Transcription Regulators in Helicobacter pylori. Int J Mol Sci 2022; 23:ijms232213688. [PMID: 36430169 PMCID: PMC9696931 DOI: 10.3390/ijms232213688] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2022] [Revised: 10/31/2022] [Accepted: 11/04/2022] [Indexed: 11/09/2022] Open
Abstract
Bacterial pathogens employ a general strategy to overcome host defenses by coordinating the virulence gene expression using dedicated regulatory systems that could raise intricate networks. During the last twenty years, many studies of Helicobacter pylori, a human pathogen responsible for various stomach diseases, have mainly focused on elucidating the mechanisms and functions of virulence factors. In parallel, numerous studies have focused on the molecular mechanisms that regulate gene transcription to attempt to understand the physiological changes of the bacterium during infection and adaptation to the environmental conditions it encounters. The number of regulatory proteins deduced from the genome sequence analyses responsible for the correct orchestration of gene transcription appears limited to 14 regulators and three sigma factors. Furthermore, evidence is accumulating for new and complex circuits regulating gene transcription and H. pylori virulence. Here, we focus on the molecular mechanisms used by H. pylori to control gene transcription as a function of the principal environmental changes.
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Muranishi K, Ishimori K, Uchida T. Regulation of the expression of the nickel uptake system in Vibrio cholerae by iron and heme via ferric uptake regulator (Fur). J Inorg Biochem 2022; 228:111713. [PMID: 35032924 DOI: 10.1016/j.jinorgbio.2022.111713] [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: 10/06/2021] [Revised: 12/27/2021] [Accepted: 01/01/2022] [Indexed: 11/30/2022]
Abstract
Fur (ferric uptake regulator) is a transcription factor that regulates expression of downstream genes containing a specific Fe2+-binding sequence called the Fur box. In Vibrio cholerae, a Fur box is located upstream of the nik operon, which is responsible for nickel uptake, suggesting that its expression is regulated by Fur. However, there are no reports that Ni2+ induces expression of Fur box genes. Accordingly, we here investigated whether Ni2+ or Fe2+ binds to Fur to regulate expression of the nik operon. We found that Fur binds to the Fur box in the presence of Fe2+ with a dissociation constant (Kd) of 1.2 μM, whereas only non-specific binding was observed in the presence of Ni2+. Thus, Fur-mediated expression of the nik operon is dependent on Fe2+, but not Ni2+. Since most iron in cells exists as heme, we examined the effect of heme on the Fur box binding activity of V. cholerae Fur (VcFur). Addition of heme to the VcFur-Fur box complex induced dissociation of VcFur from the Fur box, indicating that expression of the V. cholerae nik operon is regulated by both iron and heme. Furthermore, VCA1098, a nik operon-encoded protein, bound heme with a Kd of 1.3 μM. Collectively, our results suggest that the V. cholerae nik operon is involved not only in nickel uptake but also in heme uptake, and depends on iron and heme concentrations within bacteria.
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Affiliation(s)
- Kazuyoshi Muranishi
- Graduate School of Chemical Sciences and Engineering, Hokkaido University, Sapporo 060-8628, Japan
| | - Koichiro Ishimori
- Graduate School of Chemical Sciences and Engineering, Hokkaido University, Sapporo 060-8628, Japan; Department of Chemistry, Faculty of Science, Hokkaido University, Sapporo 060-0810, Japan
| | - Takeshi Uchida
- Graduate School of Chemical Sciences and Engineering, Hokkaido University, Sapporo 060-8628, Japan; Department of Chemistry, Faculty of Science, Hokkaido University, Sapporo 060-0810, Japan.
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5
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Sarvan S, Charih F, Askoura M, Butcher J, Brunzelle JS, Stintzi A, Couture JF. Functional insights into the interplay between DNA interaction and metal coordination in ferric uptake regulators. Sci Rep 2018; 8:7140. [PMID: 29739988 PMCID: PMC5940780 DOI: 10.1038/s41598-018-25157-6] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2018] [Accepted: 04/11/2018] [Indexed: 12/19/2022] Open
Abstract
Ferric uptake regulators (Fur) are a family of transcription factors coupling gene regulatory events to metal concentration. Recent evidence has expanded the mechanistic repertoires employed by Fur to activate or repress gene expression in the presence or absence of regulatory metals. However, the mechanistic basis underlying this extended repertoire has remained largely unexplored. In this study, we used an extensive set of mutations to demonstrate that Campylobacter jejuni Fur (CjFur) employs the same surface to positively and negatively control gene expression regardless of the presence or absence of metals. Moreover, the crystal structure determination of a CjFur devoid of any regulatory metals shows that subtle reorientation of the transcription factor DNA binding domain negatively impacts DNA binding, gene expression and gut colonization in chickens. Overall, these results highlight the versatility of the CjFur DNA binding domain in mediating all gene regulatory events controlled by the metalloregulator and that the full metalation of CjFur is critical to the Campylobacter jejuni life cycle in vivo.
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Affiliation(s)
- Sabina Sarvan
- Ottawa Institute of Systems Biology, Department of Biochemistry, Microbiology and Immunology, University of Ottawa, 451 Smyth Road, Ottawa, Ontario, K1H 8M5, Canada
| | - François Charih
- Ottawa Institute of Systems Biology, Department of Biochemistry, Microbiology and Immunology, University of Ottawa, 451 Smyth Road, Ottawa, Ontario, K1H 8M5, Canada
| | - Momen Askoura
- Ottawa Institute of Systems Biology, Department of Biochemistry, Microbiology and Immunology, University of Ottawa, 451 Smyth Road, Ottawa, Ontario, K1H 8M5, Canada.,Department of Microbiology and Immunology, Faculty of Pharmacy, Zagazig University, Zagazig, Egypt
| | - James Butcher
- Ottawa Institute of Systems Biology, Department of Biochemistry, Microbiology and Immunology, University of Ottawa, 451 Smyth Road, Ottawa, Ontario, K1H 8M5, Canada
| | - Joseph S Brunzelle
- Feinberg School of Medicine, Department of Molecular Pharmacology and Biological Chemistry, Northwestern University, Chicago, Illinois, 60611, USA
| | - Alain Stintzi
- Ottawa Institute of Systems Biology, Department of Biochemistry, Microbiology and Immunology, University of Ottawa, 451 Smyth Road, Ottawa, Ontario, K1H 8M5, Canada
| | - Jean-François Couture
- Ottawa Institute of Systems Biology, Department of Biochemistry, Microbiology and Immunology, University of Ottawa, 451 Smyth Road, Ottawa, Ontario, K1H 8M5, Canada.
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6
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Whitmire JM, Merrell DS. Use of Random and Site-Directed Mutagenesis to Probe Protein Structure-Function Relationships: Applied Techniques in the Study of Helicobacter pylori. Methods Mol Biol 2017; 1498:461-480. [PMID: 27709595 DOI: 10.1007/978-1-4939-6472-7_31] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Mutagenesis is a valuable tool to examine the structure-function relationships of bacterial proteins. As such, a wide variety of mutagenesis techniques and strategies have been developed. This chapter details a selection of random mutagenesis methods and site-directed mutagenesis procedures that can be applied to an array of bacterial species. Additionally, the direct application of the techniques to study the Helicobacter pylori Ferric Uptake Regulator (Fur) protein is described. The varied approaches illustrated herein allow the robust investigation of the structural-functional relationships within a protein of interest.
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Affiliation(s)
- Jeannette M Whitmire
- Department of Microbiology and Immunology, Uniformed Services University of the Health Sciences, 4301 Jones Bridge Road, Bethesda, MD, 20814, USA
| | - D Scott Merrell
- Department of Microbiology and Immunology, Uniformed Services University of the Health Sciences, 4301 Jones Bridge Road, Bethesda, MD, 20814, USA.
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7
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Helicobacter pylori adaptation in vivo in response to a high-salt diet. Infect Immun 2015; 83:4871-83. [PMID: 26438795 DOI: 10.1128/iai.00918-15] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2015] [Accepted: 09/30/2015] [Indexed: 12/21/2022] Open
Abstract
Helicobacter pylori exhibits a high level of intraspecies genetic diversity. In this study, we investigated whether the diversification of H. pylori is influenced by the composition of the diet. Specifically, we investigated the effect of a high-salt diet (a known risk factor for gastric adenocarcinoma) on H. pylori diversification within a host. We analyzed H. pylori strains isolated from Mongolian gerbils fed either a high-salt diet or a regular diet for 4 months by proteomic and whole-genome sequencing methods. Compared to the input strain and output strains from animals fed a regular diet, the output strains from animals fed a high-salt diet produced higher levels of proteins involved in iron acquisition and oxidative-stress resistance. Several of these changes were attributable to a nonsynonymous mutation in fur (fur-R88H). Further experiments indicated that this mutation conferred increased resistance to high-salt conditions and oxidative stress. We propose a model in which a high-salt diet leads to high levels of gastric inflammation and associated oxidative stress in H. pylori-infected animals and that these conditions, along with the high intraluminal concentrations of sodium chloride, lead to selection of H. pylori strains that are most fit for growth in this environment.
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8
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A Mur regulator protein in the extremophilic bacterium Deinococcus radiodurans. PLoS One 2014; 9:e106341. [PMID: 25243898 PMCID: PMC4171365 DOI: 10.1371/journal.pone.0106341] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2014] [Accepted: 07/29/2014] [Indexed: 12/11/2022] Open
Abstract
Ferric uptake regulator (Fur) is a transcriptional regulator that controls the expression of genes involved in the uptake of iron and manganese, as well as vital nutrients, and is essential for intracellular redox cycling. We identified a unique Fur homolog (DR0865) from Deinococcus radiodurans, which is known for its extreme resistance to radiation and oxidants. A dr0865 mutant (Mt-0865) showed a higher sensitivity to manganese stress, hydrogen peroxide, gamma irradiation and ultraviolet (UV) irradiation than the wild-type R1 strain. Cellular manganese (Mn) ion (Mn2+) analysis showed that Mn2+, copper (Cu2+), and ferric (Fe3+) ions accumulated significantly in the mutant, which suggests that the dr0865 gene is not only involved in the regulation of Mn2+ homeostasis, but also affects the uptake of other ions. In addition, transcriptome profiles under MnCl2 stress showed that the expression of many genes involved in Mn metabolism was significantly different in the wild-type R1 and DR0865 mutant (Mt-0865). Furthermore, we found that the dr0865 gene serves as a positive regulator of the manganese efflux pump gene mntE (dr1236), and as a negative regulator of Mn ABC transporter genes, such as dr2283, dr2284 and dr2523. Therefore, it plays an important role in maintaining the homoeostasis of intracellular Mn (II), and also other Mn2+, zinc (Zn2+) and Cu2+ ions. Based on its role in manganese homeostasis, DR0865 likely belongs to the Mur sub-family of Fur homolog.
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9
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Abstract
Helicobacter pylori relies on multiple colonization and virulence factors to persist in the human stomach for life. In addition, these factors can be modulated and vary to suit the ever-changing environment within the host individual. This article outlines the novel developments in this field of research during the past year, highlighting the cag pathogenicity island, VacA, γ-glutamyl-transpeptidase as well as including recent advances in protein structure, bacteria-host interaction, and the role of stomach microbiota.
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10
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Agriesti F, Roncarati D, Musiani F, Del Campo C, Iurlaro M, Sparla F, Ciurli S, Danielli A, Scarlato V. FeON-FeOFF: the Helicobacter pylori Fur regulator commutates iron-responsive transcription by discriminative readout of opposed DNA grooves. Nucleic Acids Res 2013; 42:3138-51. [PMID: 24322295 PMCID: PMC3950669 DOI: 10.1093/nar/gkt1258] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/04/2022] Open
Abstract
Most transcriptional regulators bind nucleotide motifs in the major groove, although some are able to recognize molecular determinants conferred by the minor groove of DNA. Here we report a transcriptional commutator switch that exploits the alternative readout of grooves to mediate opposite output regulation for the same input signal. This mechanism accounts for the ability of the Helicobacter pylori Fur regulator to repress the expression of both iron-inducible and iron-repressible genes. When iron is scarce, Fur binds to DNA as a dimer, through the readout of thymine pairs in the major groove, repressing iron-inducible transcription (FeON). Conversely, on iron-repressible elements the metal ion acts as corepressor, inducing Fur multimerization with consequent minor groove readout of AT-rich inverted repeats (FeOFF). Our results provide first evidence for a novel regulatory paradigm, in which the discriminative readout of DNA grooves enables to toggle between the repression of genes in a mutually exclusive manner.
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Affiliation(s)
- Francesca Agriesti
- Department of Pharmacy and Biotechnology (FaBiT), University of Bologna, 40126 Bologna, Italy
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