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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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Sarkar D, Sau AK. Illuminating the structure-function landscape of an evolutionary nonconserved motif in the arginases of Helicobacter gastric pathogens. IUBMB Life 2023; 75:782-793. [PMID: 37086465 DOI: 10.1002/iub.2728] [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: 12/08/2022] [Accepted: 04/03/2023] [Indexed: 04/24/2023]
Abstract
The bimetallic enzyme arginase catalyses the conversion of L-arginine to L-ornithine and urea. In Helicobacter pylori (a known human gastric pathogen), this enzyme is an important virulence factor. In spite of the conservation of the catalytic and the metal-binding residues, the H. pylori homolog possesses a 13-residue motif (-153 ESEEKAWQKLCSL165 -) present in the middle of the protein sequence, whose role was recently elucidated. Despite several reviews available on arginases, no report has thoroughly illustrated the underlying basis for the importance of the above motif of the H. pylori enzyme in structure and function. In this review, we systematically describe a mechanistic basis for its importance in structure and function based on the known data. This motif of the H. pylori enzyme is present exclusively in the arginases of other Helicobacter gastric pathogens, where the critical residues are conserved, implying that the nonconserved stretch has been selected during the evolution of the enzyme in these gastric pathogens in a specific manner to perform its role in the structure and function. The combined information can be useful for understanding the function of arginases in other Helicobacter gastric pathogens. Additionally, this knowledge can be utilised to screen and design new small molecule inhibitors, specific to the arginases of these pathogens.
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Affiliation(s)
- Ditsa Sarkar
- Protein Engineering Laboratory, National Institute of Immunology, New Delhi, Delhi, India
| | - Apurba Kumar Sau
- Protein Engineering Laboratory, National Institute of Immunology, New Delhi, Delhi, India
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Gómez-Garzón C, Payne SM. Divide and conquer: genetics, mechanism, and evolution of the ferrous iron transporter Feo in Helicobacter pylori. Front Microbiol 2023; 14:1219359. [PMID: 37469426 PMCID: PMC10353542 DOI: 10.3389/fmicb.2023.1219359] [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: 05/09/2023] [Accepted: 06/14/2023] [Indexed: 07/21/2023] Open
Abstract
Introduction Feo is the most widespread and conserved system for ferrous iron uptake in bacteria, and it is important for virulence in several gastrointestinal pathogens. However, its mechanism remains poorly understood. Hitherto, most studies regarding the Feo system were focused on Gammaproteobacterial models, which possess three feo genes (feoA, B, and C) clustered in an operon. We found that the human pathogen Helicobacter pylori possesses a unique arrangement of the feo genes, in which only feoA and feoB are present and encoded in distant loci. In this study, we examined the functional significance of this arrangement. Methods Requirement and regulation of the individual H. pylori feo genes were assessed through in vivo assays and gene expression profiling. The evolutionary history of feo was inferred via phylogenetic reconstruction, and AlphaFold was used for predicting the FeoA-FeoB interaction. Results and Discussion Both feoA and feoB are required for Feo function, and feoB is likely subjected to tight regulation in response to iron and nickel by Fur and NikR, respectively. Also, we established that feoA is encoded in an operon that emerged in the common ancestor of most, but not all, helicobacters, and this resulted in feoA transcription being controlled by two independent promoters. The H. pylori Feo system offers a new model to understand ferrous iron transport in bacterial pathogens.
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Affiliation(s)
- Camilo Gómez-Garzón
- Department of Molecular Biosciences, University of Texas at Austin, Austin, TX, United States
| | - Shelley M. Payne
- Department of Molecular Biosciences, University of Texas at Austin, Austin, TX, United States
- John Ring LaMontagne Center for Infectious Disease, The University of Texas at Austin, Austin, TX, United States
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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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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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Bacterial Membrane Vesicles as a Novel Strategy for Extrusion of Antimicrobial Bismuth Drug in Helicobacter pylori. mBio 2022; 13:e0163322. [PMID: 36154274 PMCID: PMC9601102 DOI: 10.1128/mbio.01633-22] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
Abstract
Bacterial antibiotic resistance is a major threat to human health. A combination of antibiotics with metals is among the proposed alternative treatments. Only one such combination is successfully used in clinics; it associates antibiotics with the metal bismuth to treat infections by Helicobacter pylori. This bacterial pathogen colonizes the human stomach and is associated with gastric cancer, killing 800,000 individuals yearly. The effect of bismuth in H. pylori treatment is not well understood in particular for sublethal doses such as those measured in the plasma of treated patients. We addressed this question and observed that bismuth induces the formation of homogeneously sized membrane vesicles (MVs) with unique protein cargo content enriched in bismuth-binding proteins, as shown by quantitative proteomics. Purified MVs of bismuth-exposed bacteria were strongly enriched in bismuth as measured by inductively coupled plasma optical emission spectrometry (ICP-OES), unlike bacterial cells from which they originate. Thus, our results revealed a novel function of MVs in bismuth detoxification, where secreted MVs act as tool to discard bismuth from the bacteria. Bismuth also induces the formation of intracellular polyphosphate granules that are associated with changes in nucleoid structure. Nucleoid compaction in response to bismuth was established by immunogold electron microscopy and refined by the first chromosome conformation capture (Hi-C) analysis of H. pylori. Our results reveal that even low doses of bismuth induce profound changes in H. pylori physiology and highlight a novel defense mechanism that involves MV-mediated bismuth extrusion from the bacteria and a probable local DNA protective response where polyphosphate granules are associated with nucleoid compaction.
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Kelley BR, Lu J, Haley KP, Gaddy JA, Johnson JG. Metal homeostasis in pathogenic Epsilonproteobacteria: mechanisms of acquisition, efflux, and regulation. Metallomics 2021; 13:mfaa002. [PMID: 33570133 PMCID: PMC8043183 DOI: 10.1093/mtomcs/mfaa002] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2020] [Revised: 11/25/2020] [Accepted: 12/03/2020] [Indexed: 12/14/2022]
Abstract
Epsilonproteobacteria are a diverse class of eubacteria within the Proteobacteria phylum that includes environmental sulfur-reducing bacteria and the human pathogens, Campylobacter jejuni and Helicobacter pylori. These pathogens infect and proliferate within the gastrointestinal tracts of multiple animal hosts, including humans, and cause a variety of disease outcomes. While infection of these hosts provides nutrients for the pathogenic Epsilonproteobacteria, many hosts have evolved a variety of strategies to either sequester metals from the invading pathogen or exploit the toxicity of metals and drive their accumulation as an antimicrobial strategy. As a result, C. jejuni and H. pylori have developed mechanisms to sense changes in metal availability and regulate their physiology in order to respond to either metal limitation or accumulation. In this review, we will discuss the challenges of metal availability at the host-pathogen interface during infection with C. jejuni and H. pylori and describe what is currently known about how these organisms alter their gene expression and/or deploy bacterial virulence factors in response to these environments.
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Affiliation(s)
- Brittni R Kelley
- Department of Microbiology, University of Tennessee, Knoxville, TN, USA
| | - Jacky Lu
- Department of Pathology, Microbiology and Immunology, Vanderbilt University, Nashville, TN, USA
| | - Kathryn P Haley
- Department of Biology, Grand Valley State University, Grand Rapids, MI, USA
| | - Jennifer A Gaddy
- Department of Pathology, Microbiology and Immunology, Vanderbilt University, Nashville, TN, USA
- Tennessee Valley Healthcare Systems, Department of Veterans Affairs, Nashville, TN, USA
- Department of Medicine, Vanderbilt University Medical Center, Nashville, TN, USA
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Maintenance of Type IV Secretion Function During Helicobacter pylori Infection in Mice. mBio 2020; 11:mBio.03147-20. [PMID: 33443133 PMCID: PMC8534286 DOI: 10.1128/mbio.03147-20] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
The Helicobacter pylori type IV secretion system (T4SS) encoded on the cag pathogenicity island (cagPAI) secretes the CagA oncoprotein and other effectors into the gastric epithelium. During murine infection, T4SS function is lost in an immune-dependent manner, typically as a result of in-frame recombination in the middle repeat region of cagY, though single nucleotide polymorphisms (SNPs) in cagY or in other essential genes may also occur. Loss of T4SS function also occurs in gerbils, nonhuman primates, and humans, suggesting that it is biologically relevant and not simply an artifact of the murine model. Here, we sought to identify physiologically relevant conditions under which T4SS function is maintained in the murine model. We found that loss of H. pylori T4SS function in mice was blunted by systemic Salmonella coinfection and completely eliminated by dietary iron restriction. Both have epidemiologic parallels in humans, since H. pylori strains from individuals in developing countries, where iron deficiency and systemic infections are common, are also more often cagPAI+ than strains from developed countries. These results have implications for our fundamental understanding of the cagPAI and also provide experimental tools that permit the study of T4SS function in the murine model.IMPORTANCE The type IV secretion system (T4SS) is the major Helicobacter pylori virulence factor, though its function is lost during murine infection. Loss of function also occurs in gerbils and in humans, suggesting that it is biologically relevant, but the conditions under which T4SS regulation occurs are unknown. Here, we found that systemic coinfection with Salmonella and iron deprivation each promote retention of T4SS function. These results improve our understanding of the cag pathogenicity island (cagPAI) and provide experimental tools that permit the study of T4SS function in the murine model.
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Shoyama FM, Janetanakit T, Bannantine JP, Barletta RG, Sreevatsan S. Elucidating the Regulon of a Fur -like Protein in Mycobacterium avium subsp. paratuberculosis ( MAP). Front Microbiol 2020; 11:598. [PMID: 32390963 PMCID: PMC7192006 DOI: 10.3389/fmicb.2020.00598] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2019] [Accepted: 03/18/2020] [Indexed: 11/13/2022] Open
Abstract
Intracellular iron concentration is tightly regulated to maintain cell viability. Iron plays important roles in electron transport, nucleic acid synthesis, and oxidative stress. A Mycobacterium avium subsp. paratuberculosis (MAP)-specific genomic island carries a putative metal transport operon that includes MAP3773c, which encodes a Fur-like protein. Although well characterized as a global regulator of iron homeostasis in multiple bacteria, the function of Fur (ferric uptake regulator) in MAP is unknown as this organism also carries IdeR (iron dependent regulator), a native iron regulatory protein specific to mycobacteria. Computational analysis using PRODORIC identified 23 different pathways involved in respiration, metabolism, and virulence that were likely regulated by MAP3773c. Thus, chromatin immunoprecipitation followed by high-throughput sequencing (ChIP-seq) was performed to confirm the putative regulon of MAP3773c (Fur-like protein) in MAP. ChIP-Seq revealed enriched binding to 58 regions by Fur under iron-replete and -deplete conditions, located mostly within open reading frames (ORFs). Three ChIP peaks were identified in genes that are directly related to iron regulation: MAP3638c (hemophore-like protein), MAP3736c (Fur box), and MAP3776c (ABC transporter). Fur box consensus sequence was identified, and binding specificity and dependence on Mn2+ availability was confirmed by a chemiluminescent electrophoresis mobility shift assay (EMSA). The results confirmed that MAP3773c is a Fur ortholog that recognizes a 19 bp DNA sequence motif (Fur box) and it is involved in metal homeostasis. This work provides a regulatory network of MAP Fur binding sites during iron-replete and -deplete conditions, highlighting unique properties of Fur regulon in MAP.
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Affiliation(s)
- Fernanda Miyagaki Shoyama
- Department of Pathobiology and Diagnostic Investigation, College of Veterinary Medicine, Michigan State University, East Lansing, MI, United States
| | - Taveesak Janetanakit
- Department of Veterinary Public Health, Faculty of Veterinary Science, Chulalongkorn University, Bangkok, Thailand
| | - John P. Bannantine
- National Animal Disease Center, USDA-Agricultural Research Service, Ames, IA, United States
| | - Raul G. Barletta
- School of Veterinary Medicine and Biomedical Sciences, University of Nebraska, Lincoln, NE, United States
| | - Srinand Sreevatsan
- Department of Pathobiology and Diagnostic Investigation, College of Veterinary Medicine, Michigan State University, East Lansing, MI, United States
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Šeligová B, Lukáč Ľ, Bábelová M, Vávrová S, Sulo P. Diagnostic reliability of nested PCR depends on the primer design and threshold abundance of Helicobacter pylori in biopsy, stool, and saliva samples. Helicobacter 2020; 25:e12680. [PMID: 32057175 DOI: 10.1111/hel.12680] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/29/2019] [Revised: 12/23/2019] [Accepted: 01/25/2020] [Indexed: 12/19/2022]
Abstract
BACKGROUND The aim of this work was to find a reliable nested PCR for the detection of Helicobacter pylori in biopsy, stool, and saliva specimens. MATERIALS AND METHODS Novel nested PCR was elaborated and validated on 81 clinical biopsy, stool, and saliva samples from the same individual and compared to available H pylori assays: histology, rapid urease test (RUT), stool antigen test (SAT), 13 C-urea breath test (UBT). RESULTS The efficiency and selectivity of 17 published nested polymerase chain reactions (PCR) available for Helicobacter pylori detection were re-evaluated. Most of them had serious limitations and mistakes in primer design. Hence, we elaborated a nested PCR for the unambiguous identification of H pylori in biopsy, stool, and saliva, using primers targeted to variable regions of the 16S ribosomal RNA (rRNA) gene. Moreover, we determined the detection limit by adding a known number of cells. This number was as low as 0.5 cells in a PCR vial, but due to the DNA isolation procedures, it required 1-5 × 103 cells/g or ml of specimen. The sensitivity for nested PCR from stomach biopsies was on the same scale as 13 C-UBT (93.8%), but it was much lower in amplifications from stool (31.3%). Sequencing of all obtained PCR products exclusively confirmed H pylori-specific DNA sequences. CONCLUSIONS Elaborated nested PCR assay can serve as an auxiliary method for controversial samples (patients with bleeding or taking proton-pump inhibitor) in laboratories with basic equipment. The sensitivity and specificity for the amplification from gastric biopsies was almost like 13 C-UBT. Despite the good sensitivity, the threshold occurrence and the ability to survive in the oral cavity aside from and independent of the stomach is the reason why H pylori DNA cannot be reliably detected in saliva, stool, and some biopsy samples.
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Affiliation(s)
- Barbora Šeligová
- Department of Biochemistry, Faculty of Natural Sciences, Comenius University, Bratislava, Slovakia
| | - Ľudovít Lukáč
- First Department of Internal Medicine, Faculty of Medicine, Comenius University, Bratislava, Slovakia
| | - Michaela Bábelová
- Department of Biochemistry, Faculty of Natural Sciences, Comenius University, Bratislava, Slovakia
| | - Silvia Vávrová
- Department of Molecular Biology, Faculty of Natural Sciences, Comenius University, Bratislava, Slovakia
| | - Pavol Sulo
- Department of Biochemistry, Faculty of Natural Sciences, Comenius University, Bratislava, Slovakia
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Olaya-Abril A, Pérez MD, Cabello P, Martignetti D, Sáez LP, Luque-Almagro VM, Moreno-Vivián C, Roldán MD. Role of the Dihydrodipicolinate Synthase DapA1 on Iron Homeostasis During Cyanide Assimilation by the Alkaliphilic Bacterium Pseudomonas pseudoalcaligenes CECT5344. Front Microbiol 2020; 11:28. [PMID: 32038602 PMCID: PMC6989483 DOI: 10.3389/fmicb.2020.00028] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2019] [Accepted: 01/08/2020] [Indexed: 11/13/2022] Open
Abstract
Cyanide is a toxic compound widely used in mining and jewelry industries, as well as in the synthesis of many different chemicals. Cyanide toxicity derives from its high affinity for metals, which causes inhibition of relevant metalloenzymes. However, some cyanide-degrading microorganisms like the alkaliphilic bacterium Pseudomonas pseudoalcaligenes CECT5344 may detoxify hazardous industrial wastewaters that contain elevated cyanide and metal concentrations. Considering that iron availability is strongly reduced in the presence of cyanide, mechanisms for iron homeostasis should be required for cyanide biodegradation. Previous omic studies revealed that in the presence of a cyanide-containing jewelry residue the strain CECT5344 overproduced the dihydrodipicolinate synthase DapA1, a protein involved in lysine metabolism that also participates in the synthesis of dipicolinates, which are excellent metal chelators. In this work, a dapA1 - mutant of P. pseudoalcaligenes CECT5344 has been generated and characterized. This mutant showed reduced growth and cyanide consumption in media with the cyanide-containing wastewater. Intracellular levels of metals like iron, copper and zinc were increased in the dapA1 - mutant, especially in cells grown with the jewelry residue. In addition, a differential quantitative proteomic analysis by LC-MS/MS was carried out between the wild-type and the dapA1 - mutant strains in media with jewelry residue. The mutation in the dapA1 gene altered the expression of several proteins related to urea cycle and metabolism of arginine and other amino acids. Additionally, the dapA1 - mutant showed increased levels of the global nitrogen regulator PII and the glutamine synthetase. This proteomic study has also highlighted that the DapA1 protein is relevant for cyanide resistance, oxidative stress and iron homeostasis response, which is mediated by the ferric uptake regulator Fur. DapA1 is required to produce dipicolinates that could act as iron chelators, conferring protection against oxidative stress and allowing the regeneration of Fe-S centers to reactivate cyanide-damaged metalloproteins.
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Affiliation(s)
- Alfonso Olaya-Abril
- Departamento de Bioquímica y Biología Molecular, Universidad de Córdoba, Córdoba, Spain
| | - María Dolores Pérez
- Departamento de Bioquímica y Biología Molecular, Universidad de Córdoba, Córdoba, Spain
| | - Purificación Cabello
- Departamento de Botánica, Ecología y Fisiología Vegetal, Edificio Celestino Mutis, Campus de Rabanales, Universidad de Córdoba, Córdoba, Spain
| | - Diego Martignetti
- Departamento de Bioquímica y Biología Molecular, Universidad de Córdoba, Córdoba, Spain
| | - Lara Paloma Sáez
- Departamento de Bioquímica y Biología Molecular, Universidad de Córdoba, Córdoba, Spain
| | | | - Conrado Moreno-Vivián
- Departamento de Bioquímica y Biología Molecular, Universidad de Córdoba, Córdoba, Spain
| | - María Dolores Roldán
- Departamento de Bioquímica y Biología Molecular, Universidad de Córdoba, Córdoba, Spain
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Lv T, Dai F, Zhuang Q, Zhao X, Shao Y, Guo M, Lv Z, Li C, Zhang W. Outer membrane protein OmpU is related to iron balance in Vibrio alginolyticus. Microbiol Res 2019; 230:126350. [PMID: 31629270 DOI: 10.1016/j.micres.2019.126350] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2019] [Revised: 10/01/2019] [Accepted: 10/06/2019] [Indexed: 12/14/2022]
Abstract
Outer membrane protein U (OmpU) is a major porin from Vibrio alginolyticus and has been considered a vaccine candidate against infection by V. alginolyticus. After pre-incubated with polyclonal antibody against rOmpU, V. alginolyticus showed a 78% decrease in extracellular iron level, suggesting that interruption of OmpU could increase intracellular iron level. The mRNA expression of ompU under iron-limited conditions was determined using real-time reverse transcriptase PCR. The mRNA level of ompU was downregulated to 0.27-, 0.036- and 0.019-fold after the addition of the iron chelator 2,2'-bipyridyl for 10, 30 and 60 min, respectively. In addition, the promoter of ompU contained a ferric uptake regulator (Fur) binding site, which revealed the potential regulation of ompU by Fur and iron. Fur from V. alginolyticus was purified and used for electrophoretic mobility shift assay. The result showed that in the absence of Fe2+, purified recombinant Fur could specifically bind to the promoter DNA of ompU, while in the presence of Fe2+, the binding of Fur and the promoter DNA was suppressed. Our study preliminarily explored the function of OmpU in iron balance in V. alginolyticus, and these findings were helpful in understanding iron metabolism in V. alginolyticus.
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Affiliation(s)
- Tengteng Lv
- State Key Laboratory for Quality and Safety of Agro-products, Ningbo University, Ningbo, 315211, PR China
| | - Fa Dai
- State Key Laboratory for Quality and Safety of Agro-products, Ningbo University, Ningbo, 315211, PR China
| | - Qiuting Zhuang
- State Key Laboratory for Quality and Safety of Agro-products, Ningbo University, Ningbo, 315211, PR China
| | - Xuelin Zhao
- State Key Laboratory for Quality and Safety of Agro-products, Ningbo University, Ningbo, 315211, PR China
| | - Yina Shao
- State Key Laboratory for Quality and Safety of Agro-products, Ningbo University, Ningbo, 315211, PR China
| | - Ming Guo
- State Key Laboratory for Quality and Safety of Agro-products, Ningbo University, Ningbo, 315211, PR China
| | - Zhimeng Lv
- State Key Laboratory for Quality and Safety of Agro-products, Ningbo University, Ningbo, 315211, PR China
| | - Chenghua Li
- State Key Laboratory for Quality and Safety of Agro-products, Ningbo University, Ningbo, 315211, PR China; Laboratory for Marine Fisheries Science and Food Production Processes, Qingdao National Laboratory for Marine Science and Technology, Qingdao, 266071, PR China
| | - Weiwei Zhang
- State Key Laboratory for Quality and Safety of Agro-products, Ningbo University, Ningbo, 315211, PR China.
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Ohishi T, Masuda T, Abe H, Hayashi C, Adachi H, Ohba SI, Igarashi M, Watanabe T, Mimuro H, Amalia E, Inaoka DK, Mochizuki K, Kita K, Shibasaki M, Kawada M. Monotherapy with a novel intervenolin derivative, AS-1934, is an effective treatment for Helicobacter pylori infection. Helicobacter 2018; 23:e12470. [PMID: 29488678 DOI: 10.1111/hel.12470] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
BACKGROUND Helicobacter pylori (H. pylori) infection causes various gastrointestinal diseases including gastric cancer. Hence, eradication of this infection could prevent these diseases. The most popular first-line treatment protocol to eradicate H. pylori is termed "triple therapy" and consists of a proton pump inhibitor (PPI), clarithromycin, and amoxicillin or metronidazole. However, the antibiotics used to treat H. pylori infection are hindered by the antibiotics-resistant bacteria and by their antimicrobial activity against intestinal bacteria, leading to side effects. Therefore, an alternative treatment with fewer adverse side effects is urgently required to improve the overall eradication rate of H. pylori. OBJECTIVE The aim of this study was to assess the effectiveness and mechanism of action of an antitumor agent, intervenolin, and its derivatives as an agent for the treatment of H. pylori infection. RESULTS We demonstrate that intervenolin, and its derivatives showed selective anti-H. pylori activity, including antibiotic-resistant strains, without any effect on intestinal bacteria. We showed that dihydroorotate dehydrogenase, a key enzyme for de novo pyrimidine biosynthesis, is a target and treatment with intervenolin or its derivatives decreased the protein and mRNA levels of H. pylori urease, which protects H. pylori against acidic conditions in the stomach. Using a mouse model of H. pylori infection, oral monotherapy with the intervenolin derivative AS-1934 had a stronger anti-H. pylori effect than the triple therapy commonly used worldwide to eradicate H. pylori. CONCLUSION AS-1934 has potential advantages over current treatment options for H. pylori infection.
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Affiliation(s)
- Tomokazu Ohishi
- Institute of Microbial Chemistry (BIKAKEN), Numazu, Microbial Chemistry Research Foundation, Numazu-shi, Shizuoka, Japan
| | - Tohru Masuda
- Institute of Microbial Chemistry (BIKAKEN), Numazu, Microbial Chemistry Research Foundation, Numazu-shi, Shizuoka, Japan
| | - Hikaru Abe
- Institute of Microbial Chemistry (BIKAKEN), Laboratory of Synthetic Organic Chemistry, Microbial Chemistry Research Foundation, Shinagawa-ku, Tokyo, Japan
| | - Chigusa Hayashi
- Institute of Microbial Chemistry (BIKAKEN), Laboratory of Microbiology, Microbial Chemistry Research Foundation, Shinagawa-ku, Tokyo, Japan
| | - Hayamitsu Adachi
- Institute of Microbial Chemistry (BIKAKEN), Numazu, Microbial Chemistry Research Foundation, Numazu-shi, Shizuoka, Japan
| | - Shun-Ichi Ohba
- Institute of Microbial Chemistry (BIKAKEN), Numazu, Microbial Chemistry Research Foundation, Numazu-shi, Shizuoka, Japan
| | - Masayuki Igarashi
- Institute of Microbial Chemistry (BIKAKEN), Laboratory of Microbiology, Microbial Chemistry Research Foundation, Shinagawa-ku, Tokyo, Japan
| | - Takumi Watanabe
- Institute of Microbial Chemistry (BIKAKEN), Laboratory of Synthetic Organic Chemistry, Microbial Chemistry Research Foundation, Shinagawa-ku, Tokyo, Japan
| | - Hitomi Mimuro
- Division of Bacteriology, Department of Infectious Diseases Control, International Research Center for Infectious Diseases, The Institute of Medical Science, The University of Tokyo, Minato-ku, Tokyo, Japan.,Division of Infectious Disease, Department of Infection Microbiology, Research Institute for Microbial Diseases, Osaka University, Suita, Osaka, Japan
| | - Eri Amalia
- Department of Biomedical Chemistry, The University of Tokyo, Bunkyo-ku, Tokyo, Japan
| | - Daniel Ken Inaoka
- Department of Biomedical Chemistry, The University of Tokyo, Bunkyo-ku, Tokyo, Japan.,School of Tropical Medicine and Global Health, Nagasaki University, Nagasaki-shi, Nagasaki, Japan
| | - Kota Mochizuki
- Department of Immunogenetics, Institute of Tropical Medicine, Nagasaki University, Nagasaki-shi, Nagasaki, Japan
| | - Kiyoshi Kita
- Department of Biomedical Chemistry, The University of Tokyo, Bunkyo-ku, Tokyo, Japan.,School of Tropical Medicine and Global Health, Nagasaki University, Nagasaki-shi, Nagasaki, Japan
| | - Masakatsu Shibasaki
- Institute of Microbial Chemistry (BIKAKEN), Laboratory of Synthetic Organic Chemistry, Microbial Chemistry Research Foundation, Shinagawa-ku, Tokyo, Japan
| | - Manabu Kawada
- Institute of Microbial Chemistry (BIKAKEN), Numazu, Microbial Chemistry Research Foundation, Numazu-shi, Shizuoka, Japan.,Institute of Microbial Chemistry (BIKAKEN), Laboratory of Oncology, Microbial Chemistry Research Foundation, Shinagawa-ku, Tokyo, Japan
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14
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De la Cruz MA, Ares MA, von Bargen K, Panunzi LG, Martínez-Cruz J, Valdez-Salazar HA, Jiménez-Galicia C, Torres J. Gene Expression Profiling of Transcription Factors of Helicobacter pylori under Different Environmental Conditions. Front Microbiol 2017; 8:615. [PMID: 28443084 PMCID: PMC5385360 DOI: 10.3389/fmicb.2017.00615] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2016] [Accepted: 03/27/2017] [Indexed: 12/22/2022] Open
Abstract
Helicobacter pylori is a Gram-negative bacterium that colonizes the human gastric mucosa and causes peptic ulcers and gastric carcinoma. H. pylori strain 26695 has a small genome (1.67 Mb), which codes for few known transcriptional regulators that control bacterial metabolism and virulence. We analyzed by qRT-PCR the expression of 16 transcriptional regulators in H. pylori 26695, including the three sigma factors under different environmental conditions. When bacteria were exposed to acidic pH, urea, nickel, or iron, the sigma factors were differentially expressed with a particularly strong induction of fliA. The regulatory genes hrcA, hup, and crdR were highly induced in the presence of urea, nickel, and iron. In terms of biofilm formation fliA, flgR, hp1021, fur, nikR, and crdR were induced in sessile bacteria. Transcriptional expression levels of rpoD, flgR, hspR, hp1043, and cheY were increased in contact with AGS epithelial cells. Kanamycin, chloramphenicol, and tetracycline increased or decreased expression of regulatory genes, showing that these antibiotics affect the transcription of H. pylori. Our data indicate that environmental cues which may be present in the human stomach modulate H. pylori transcription.
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Affiliation(s)
- Miguel A De la Cruz
- Unidad de Investigación Médica en Enfermedades Infecciosas y Parasitarias, Hospital de Pediatria, Centro Médico Nacional Siglo XXI, Instituto Mexicano del Seguro SocialMexico City, Mexico
| | - Miguel A Ares
- Unidad de Investigación Médica en Enfermedades Infecciosas y Parasitarias, Hospital de Pediatria, Centro Médico Nacional Siglo XXI, Instituto Mexicano del Seguro SocialMexico City, Mexico
| | | | - Leonardo G Panunzi
- CNRS UMR7280, Inserm, U1104, Centre d'Immunologie de Marseille-Luminy, Aix Marseille Université UM2Marseille, France
| | - Jessica Martínez-Cruz
- Unidad de Investigación Médica en Enfermedades Infecciosas y Parasitarias, Hospital de Pediatria, Centro Médico Nacional Siglo XXI, Instituto Mexicano del Seguro SocialMexico City, Mexico
| | - Hilda A Valdez-Salazar
- Unidad de Investigación Médica en Enfermedades Infecciosas y Parasitarias, Hospital de Pediatria, Centro Médico Nacional Siglo XXI, Instituto Mexicano del Seguro SocialMexico City, Mexico
| | - César Jiménez-Galicia
- Laboratorio Clínico, Unidad Médica de Alta Especialidad, Hospital de Pediatría, Centro Médico Nacional Siglo XXI, Instituto Mexicano del Seguro SocialMexico City, Mexico
| | - Javier Torres
- Unidad de Investigación Médica en Enfermedades Infecciosas y Parasitarias, Hospital de Pediatria, Centro Médico Nacional Siglo XXI, Instituto Mexicano del Seguro SocialMexico City, Mexico
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15
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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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16
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Bradley JM, Le Brun NE, Moore GR. Ferritins: furnishing proteins with iron. J Biol Inorg Chem 2016; 21:13-28. [PMID: 26825805 PMCID: PMC4771812 DOI: 10.1007/s00775-016-1336-0] [Citation(s) in RCA: 80] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2015] [Accepted: 01/06/2016] [Indexed: 12/04/2022]
Abstract
Ferritins are a superfamily of iron oxidation, storage and mineralization proteins found throughout the animal, plant, and microbial kingdoms. The majority of ferritins consist of 24 subunits that individually fold into 4-α-helix bundles and assemble in a highly symmetric manner to form an approximately spherical protein coat around a central cavity into which an iron-containing mineral can be formed. Channels through the coat at inter-subunit contact points facilitate passage of iron ions to and from the central cavity, and intrasubunit catalytic sites, called ferroxidase centers, drive Fe2+ oxidation and O2 reduction. Though the different members of the superfamily share a common structure, there is often little amino acid sequence identity between them. Even where there is a high degree of sequence identity between two ferritins there can be major differences in how the proteins handle iron. In this review we describe some of the important structural features of ferritins and their mineralized iron cores, consider how iron might be released from ferritins, and examine in detail how three selected ferritins oxidise Fe2+ to explore the mechanistic variations that exist amongst ferritins. We suggest that the mechanistic differences reflect differing evolutionary pressures on amino acid sequences, and that these differing pressures are a consequence of different primary functions for different ferritins.
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Affiliation(s)
- Justin M Bradley
- Center for Molecular and Structural Biochemistry, School of Chemistry, University of East Anglia, Norwich Research Park, Norwich, NR4 7TJ, UK
| | - Nick E Le Brun
- Center for Molecular and Structural Biochemistry, School of Chemistry, University of East Anglia, Norwich Research Park, Norwich, NR4 7TJ, UK
| | - Geoffrey R Moore
- Center for Molecular and Structural Biochemistry, School of Chemistry, University of East Anglia, Norwich Research Park, Norwich, NR4 7TJ, UK.
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17
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Haley KP, Gaddy JA. Metalloregulation of Helicobacter pylori physiology and pathogenesis. Front Microbiol 2015; 6:911. [PMID: 26388855 PMCID: PMC4557348 DOI: 10.3389/fmicb.2015.00911] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2015] [Accepted: 08/19/2015] [Indexed: 12/23/2022] Open
Abstract
Helicobacter pylori is a Gram-negative spiral-shaped bacterium that colonizes over half of the world's population. Chronic H. pylori infection is associated with increased risk for numerous disease outcomes including gastritis, dysplasia, neoplasia, B-cell lymphoma of mucosal-associated lymphoid tissue (MALT lymphoma), and invasive adenocarcinoma. The complex interactions that occur between pathogen and host are dynamic and exquisitely regulated, and the relationship between H. pylori and its human host are no exception. To successfully colonize, and subsequently persist, within the human stomach H. pylori must temporally regulate numerous genes to ensure localization to the gastric lumen and coordinated expression of virulence factors to subvert the host's innate and adaptive immune response. H. pylori achieves this precise gene regulation by sensing subtle environmental changes including host-mediated alterations in nutrient availability and responding with dramatic global changes in gene expression. Recent studies revealed that the presence or absence of numerous metal ions encountered in the lumen of the stomach, or within host tissues, including nickel, iron, copper and zinc, can influence regulatory networks to alter gene expression in H. pylori. These expression changes modulate the deployment of bacterial virulence factors that can ultimately influence disease outcome. In this review we will discuss the environmental stimuli that are detected by H. pylori as well as the trans regulatory elements, specifically the transcription regulators and transcription factors, that allow for these significant transcriptional shifts.
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Affiliation(s)
- Kathryn P Haley
- Tennessee Valley Healthcare Services, Department of Veterans Affairs Nashville, TN, USA
| | - Jennifer A Gaddy
- Department of Medicine, Vanderbilt University School of Medicine Nashville, TN, USA ; Tennessee Valley Healthcare Services, Department of Veterans Affairs Nashville, TN, USA
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18
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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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19
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Musiani F, Ciurli S. Evolution of Macromolecular Docking Techniques: The Case Study of Nickel and Iron Metabolism in Pathogenic Bacteria. Molecules 2015; 20:14265-92. [PMID: 26251891 PMCID: PMC6332059 DOI: 10.3390/molecules200814265] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2015] [Revised: 07/23/2015] [Accepted: 07/28/2015] [Indexed: 11/24/2022] Open
Abstract
The interaction between macromolecules is a fundamental aspect of most biological processes. The computational techniques used to study protein-protein and protein-nucleic acid interactions have evolved in the last few years because of the development of new algorithms that allow the a priori incorporation, in the docking process, of experimentally derived information, together with the possibility of accounting for the flexibility of the interacting molecules. Here we review the results and the evolution of the techniques used to study the interaction between metallo-proteins and DNA operators, all involved in the nickel and iron metabolism of pathogenic bacteria, focusing in particular on Helicobacter pylori (Hp). In the first part of the article we discuss the methods used to calculate the structure of complexes of proteins involved in the activation of the nickel-dependent enzyme urease. In the second part of the article, we concentrate on two applications of protein-DNA docking conducted on the transcription factors HpFur (ferric uptake regulator) and HpNikR (nickel regulator). In both cases we discuss the technical expedients used to take into account the conformational variability of the multi-domain proteins involved in the calculations.
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Affiliation(s)
- Francesco Musiani
- Laboratory of Bioinorganic Chemistry, Department of Pharmacy and Biotechnology, University of Bologna, Viale G. Fanin 40, Bologna I-40127, Italy.
| | - Stefano Ciurli
- Laboratory of Bioinorganic Chemistry, Department of Pharmacy and Biotechnology, University of Bologna, Viale G. Fanin 40, Bologna I-40127, Italy.
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20
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Raghwan, Chowdhury R. Host cell contact induces fur-dependent expression of virulence factors CagA and VacA in Helicobacter pylori. Helicobacter 2014; 19:17-25. [PMID: 24020886 DOI: 10.1111/hel.12087] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
BACKGROUND Helicobacter pylori, a gram negative bacterium, colonizes the stomach in a majority of the world population. The two major virulence factors of H. pylori VacA and CagA, thought to be associated with chronic inflammation and disease, have been extensively studied, but the regulation of the expression of these virulence genes in H. pylori remains poorly understood. METHODS qRT-PCR was performed to quantify gene expression in unadhered and AGS-adhered H. pylori. Δfur mutant was constructed by splicing by overlap extension PCR and allelic exchange. RESULTS Adherence of H. pylori to the gastric epithelial cell line AGS strongly induces the expression of both cagA and vacA. Induction of cagA and vacA in the AGS cell-adhered H. pylori Δfur mutant strain was consistently lower than in the adhered parent strain. However, expression of the genes was similar between the wild-type and Δfur mutant strains in the unadhered state, suggesting that Fur has a role in the upregulation of cagA and vacA expression, especially in AGS-adhered H. pylori. Consistent with these results, microscopic observations revealed that infection of AGS cells with H. pylori Δfur mutant strain produced much less damage as compared to that produced by the wild-type H. pylori strain. CONCLUSIONS These results suggested that cagA and vacA gene expression is upregulated in H. pylori, especially by host cell contact, and Fur has a role in the upregulation.
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Affiliation(s)
- Raghwan
- Infectious Diseases and Immunology Division, Indian Institute of Chemical Biology, Council of Scientific and Industrial Research, Kolkata, India
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21
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Shaik MM, Cendron L, Salamina M, Ruzzene M, Zanotti G. Helicobacter pylori periplasmic receptor CeuE (HP1561) modulates its nickel affinity via organic metallophores. Mol Microbiol 2014; 91:724-35. [PMID: 24330328 DOI: 10.1111/mmi.12487] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/08/2013] [Indexed: 11/30/2022]
Abstract
In Gram-negative bacteria, nickel uptake is guaranteed by multiple and complex systems that operate at the membrane and periplasmic level. Helicobacter pylori employs other yet uncharacterized systems to import the nickel required for the maturation of key enzymes, such as urease and hydrogenase. H. pylori CeuE protein (HP1561), previously annotated as the periplasmic component of an ATP-binding cassette (ABC)-type transporter apparatus responsible of haem/siderophores or other Fe(III)-complexes uptake, has been recently proposed to be on the contrary involved in nickel/cobalt acquisition. In this work, the crystal structure of H. pylori CeuE has been determined at 1.65 Å resolution using the single anomalous dispersion (SAD) method. It comprises two structurally similar globular domains, each consisting of a central five-stranded β-sheet surrounded by α-helices, an arrangement commonly classified as a Rossmann-like fold. Structurally, H. pylori CeuE belongs to the class III periplasmic substrate-binding protein. Both crystallographic data and fluorescence binding assays allow to exclude a role of the protein in the transport of Vitamin B12, enterobactin, haem and isolated Ni(2+) ions. On the contrary, the crystal structure and plasmon resonance studies about CeuE/Ni-(l-His)2 complex indicate that in H. pylori nickel transport is supported by CeuE protein and requires the presence of a natural nickelophore, analogously to what has been recently demonstrated for NikA from Escherichia coli.
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Affiliation(s)
- Md Munan Shaik
- Department of Biomedical Sciences, University of Padua, Viale G. Colombo 3, 35131, Padua, Italy
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22
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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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23
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Pich OQ, Merrell DS. The ferric uptake regulator of Helicobacter pylori: a critical player in the battle for iron and colonization of the stomach. Future Microbiol 2013; 8:725-38. [PMID: 23701330 DOI: 10.2217/fmb.13.43] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Helicobacter pylori is arguably one of the most successful pathogens; it colonizes the stomachs of more than half of the human population. Colonization and persistence in such an inhospitable niche requires the presence of exquisite adaptive mechanisms. One of the proteins that contributes significantly to the remarkable adaptability of H. pylori is the ferric uptake regulator (Fur), which functions as a master regulator of gene expression. In addition to genes directly related to iron homeostasis, Fur controls expression of several enzymes that play a central role in metabolism and energy production. The absence of Fur leads to severe H. pylori colonization defects and, accordingly, several Fur-regulated genes have been shown to be essential for colonization. Moreover, proteins encoded by Fur-regulated genes have a strong impact on redox homeostasis in the stomach and are major determinants of inflammation. In this review, we discuss the main roles of Fur in the biology of H. pylori and highlight the importance of this regulatory protein in the infectious process.
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Affiliation(s)
- Oscar Q Pich
- Department of Microbiology & Immunology, Uniformed Services University of the Health Sciences, 4301 Jones Bridge Road, Bethesda, MD 20814, USA
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24
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Identification and characterization of novel Helicobacter pylori apo-fur-regulated target genes. J Bacteriol 2013; 195:5526-39. [PMID: 24097951 DOI: 10.1128/jb.01026-13] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
In Helicobacter pylori, the ferric uptake regulator (Fur) has evolved additional regulatory functions not seen in other bacteria; it can repress and activate different groups of genes in both its iron-bound and apo forms. Because little is understood about the process of apo-Fur repression and because only two apo-Fur-repressed genes (pfr and sodB) have previously been identified, we sought to expand our understanding of this type of regulation. Utilizing published genomic studies, we selected three potential new apo-Fur-regulated gene targets: serB, hydA, and the cytochrome c553 gene. Transcriptional analyses confirmed Fur-dependent repression of these genes in the absence of iron, as well as derepression in the absence of Fur. Binding studies showed that apo-Fur directly interacted with the suspected hydA and cytochrome c553 promoters but not that of serB, which was subsequently shown to be cotranscribed with pfr; apo-Fur-dependent regulation occurred at the pfr promoter. Alignments of apo-regulated promoter regions revealed a conserved, 6-bp consensus sequence (AAATGA). DNase I footprinting showed that this sequence lies within the protected regions of the pfr and hydA promoters. Moreover, mutation of the sequence in the pfr promoter abrogated Fur binding and DNase protection. Likewise, fluorescence anisotropy studies and binding studies with mutated consensus sequences showed that the sequence was important for apo-Fur binding to the pfr promoter. Together these studies expand the known apo-Fur regulon in H. pylori and characterize the first reported apo-Fur box sequence.
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25
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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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26
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Srivastava P, Kowshik M. Mechanisms of metal resistance and homeostasis in haloarchaea. ARCHAEA (VANCOUVER, B.C.) 2013; 2013:732864. [PMID: 23533331 PMCID: PMC3600143 DOI: 10.1155/2013/732864] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/26/2012] [Revised: 12/20/2012] [Accepted: 01/10/2013] [Indexed: 11/20/2022]
Abstract
Haloarchaea are the predominant microflora of hypersaline econiches such as solar salterns, soda lakes, and estuaries where the salinity ranges from 35 to 400 ppt. Econiches like estuaries and solar crystallizer ponds may contain high concentrations of metals since they serve as ecological sinks for metal pollution and also as effective traps for river borne metals. The availability of metals in these econiches is determined by the type of metal complexes formed and the solubility of the metal species at such high salinity. Haloarchaea have developed specialized mechanisms for the uptake of metals required for various key physiological processes and are not readily available at high salinity, beside evolving resistance mechanisms for metals with high solubility. The present paper seeks to give an overview of the main molecular mechanisms involved in metal tolerance in haloarchaea and focuses on factors such as salinity and metal speciation that affect the bioavailability of metals to haloarchaea. Global transcriptomic analysis during metal stress in these organisms will help in determining the various factors differentially regulated and essential for metal physiology.
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Affiliation(s)
- Pallavee Srivastava
- Department of Biological Sciences, Birla Institute of Technology and Science, Pilani, K K Birla Goa Campus, NH-17B, Zuarinagar, Goa 403 726, India
| | - Meenal Kowshik
- Department of Biological Sciences, Birla Institute of Technology and Science, Pilani, K K Birla Goa Campus, NH-17B, Zuarinagar, Goa 403 726, India
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27
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Fur activates expression of the 2-oxoglutarate oxidoreductase genes (oorDABC) in Helicobacter pylori. J Bacteriol 2012; 194:6490-7. [PMID: 23002221 DOI: 10.1128/jb.01226-12] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
Helicobacter pylori is a highly successful pathogen that colonizes the gastric mucosa of ∼50% of the world's population. Within this colonization niche, the bacteria encounter large fluctuations in nutrient availability. As such, it is critical that this organism regulate expression of key metabolic enzymes so that they are present when environmental conditions are optimal for growth. One such enzyme is the 2-oxoglutarate (α-ketoglutarate) oxidoreductase (OOR), which catalyzes the conversion of α-ketoglutarate to succinyl coenzyme A (succinyl-CoA) and CO(2). Previous studies from our group suggested that the genes that encode the OOR are activated by iron-bound Fur (Fe-Fur); microarray analysis showed that expression of oorD, oorA, and oorC was altered in a fur mutant strain of H. pylori. The goal of the present work was to more thoroughly characterize expression of the oorDABC genes in H. pylori as well as to define the role of Fe-Fur in this process. Here we show that these four genes are cotranscribed as an operon and that expression of the operon is decreased in a fur mutant strain. Transcriptional start site mapping and promoter analysis revealed the presence of a canonical extended -10 element but a poorly conserved -35 element upstream of the +1. Additionally, we identified a conserved Fur binding sequence ∼130 bp upstream of the transcriptional start site. Transcriptional analysis using promoter fusions revealed that this binding sequence was required for Fe-Fur-mediated activation. Finally, fluorescence anisotropy assays indicate that Fe-Fur specifically bound this Fur box with a relatively high affinity (dissociation constant [K(d)] = 200 nM). These findings provide novel insight into the genetic regulation of a key metabolic enzyme and add to our understanding of the diverse roles Fur plays in gene regulation in H. pylori.
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Morishita K, Takeuchi H, Morimoto N, Shimamura T, Kadota Y, Tsuda M, Taniguchi T, Ukeda H, Yamamoto T, Sugiura T. Superoxide dismutase activity of Helicobacter pylori per se from 158 clinical isolates and the characteristics. Microbiol Immunol 2012; 56:262-72. [DOI: 10.1111/j.1348-0421.2012.00433.x] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
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Fur-mediated activation of gene transcription in the human pathogen Neisseria gonorrhoeae. J Bacteriol 2012; 194:1730-42. [PMID: 22287521 DOI: 10.1128/jb.06176-11] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
It is well established that the ferric uptake regulatory protein (Fur) functions as a transcriptional repressor in diverse microorganisms. Recent studies demonstrated that Fur also functions as a transcriptional activator. In this study we defined Fur-mediated activation of gene transcription in the sexually transmitted disease pathogen Neisseria gonorrhoeae. Analysis of 37 genes which were previously determined to be iron induced and which contained putative Fur boxes revealed that only 30 of these genes exhibited reduced transcription in a gonococcal fur mutant strain. Fur-mediated activation was established by examining binding of Fur to the putative promoter regions of 16 Fur-activated genes with variable binding affinities observed. Only ∼50% of the newly identified Fur-regulated genes bound Fur in vitro, suggesting that additional regulatory circuits exist which may function through a Fur-mediated indirect mechanism. The gonococcal Fur-activated genes displayed variable transcription patterns in a fur mutant strain, which correlated with the position of the Fur box in each (promoter) region. These results suggest that Fur-mediated direct transcriptional activation is fulfilled by multiple mechanisms involving either competing with a repressor or recruiting RNA polymerase. Collectively, our studies have established that gonococcal Fur functions as an activator of gene transcription through both direct and indirect mechanisms.
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Iron trafficking system in Helicobacter pylori. Biometals 2011; 25:247-58. [PMID: 22127376 DOI: 10.1007/s10534-011-9512-8] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2011] [Accepted: 11/16/2011] [Indexed: 12/14/2022]
Abstract
Helicobacter pylori infections are closely associated with peptic ulcers, gastric malignancy and iron deficiency anemia. Iron is essential for almost all living organisms and the investigation of iron uptake and trafficking system is thus important to understand the pathological roles of H. pylori. Up to now, the iron trafficking system of H. pylori is not yet fully clear and merits further efforts in this regards. The available information about iron uptake and regulation has been discussed in this concise review, such as FeoB in ferrous transportation, FrpB2 in hemoglobin uptake, HugZ in heme processing, virulence factors (VacA and CagA) in transferrin utilization, Pfr and NapA in iron storage and Fur in iron regulation. The identified iron trafficking system will help us to understand the pathological roles of H. pylori in the various gastric diseases and iron deficiency anemia and stimulates further development of effective anti-bacterial drugs.
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Identification of Proteins Related to Nickel Homeostasis in Helicobater pylori by Immobilized Metal Affinity Chromatography and Two-Dimensional Gel Electrophoresis. Met Based Drugs 2011; 2008:289490. [PMID: 18288244 PMCID: PMC2225478 DOI: 10.1155/2008/289490] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2007] [Accepted: 10/21/2007] [Indexed: 12/16/2022] Open
Abstract
Helicobacter pylori (H. pylori) is a widespread human pathogen causing peptic ulcers and chronic gastritis. Maintaining nickel homeostasis is crucial for the establishment of
H. pylori infection in humans. We used immobilized-nickel affinity chromatography to isolate Ni-related proteins from H. pylori cell extracts. Two-dimensional gel electrophoresis and mass spectrometry were employed to separate and identify twenty two Ni-interacting proteins in H. pylori. These Ni-interacting proteins can be classified into several general functional categories, including cellular processes (HspA, HspB, TsaA, and NapA), enzymes (Urease, Fumarase, GuaB, Cad, PPase, and DmpI), membrane-associated proteins (OM jhp1427 and HpaA), iron storage protein (Pfr), and hypothetical proteins (HP0271, HP jhp0216, HP jhp0301, HP0721, HP0614, and HP jhp0118). The implication of these proteins in nickel homeostasis is discussed.
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Cornelis P, Wei Q, Andrews SC, Vinckx T. Iron homeostasis and management of oxidative stress response in bacteria. Metallomics 2011; 3:540-9. [PMID: 21566833 DOI: 10.1039/c1mt00022e] [Citation(s) in RCA: 188] [Impact Index Per Article: 14.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
Iron is both an essential nutrient for the growth of microorganisms, as well as a dangerous metal due to its capacity to generate reactive oxygen species (ROS) via the Fenton reaction. For these reasons, bacteria must tightly control the uptake and storage of iron in a manner that restricts the build-up of ROS. Therefore, it is not surprising to find that the control of iron homeostasis and responses to oxidative stress are coordinated. The mechanisms concerned with these processes, and the interactions involved, are the subject of this review.
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Affiliation(s)
- Pierre Cornelis
- Microbial Interactions, Department of Molecular and Cellular Interactions, VIB and Vrije Universiteit Brussel, Pleinlaan 2, 1050 Brussels, Belgium.
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Gancz H, Merrell DS. The Helicobacter pylori Ferric Uptake Regulator (Fur) is essential for growth under sodium chloride stress. J Microbiol 2011; 49:294-8. [PMID: 21538253 DOI: 10.1007/s12275-011-0396-7] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2010] [Accepted: 11/22/2010] [Indexed: 01/27/2023]
Abstract
Epidemiological data and animal models indicate that Helicobacter pylori and dietary NaCl have a synergistic ill effect on gastric maladies. Here we show that the Ferric Uptake Regulator (Fur), which is a crucial regulatory factor required for H. pylori colonization, is essential for growth in the presence of high NaCl concentrations. Moreover, we demonstrate that the transcriptional response induced by sodium chloride stress exhibits similarities to that seen under iron depletion.
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Affiliation(s)
- Hanan Gancz
- Department of Microbiology and Immunology, Uniformed Services University of Health Sciences, 4301 Jones Bridge Rd., Bethesda, MD 20814, USA
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Gilbreath JJ, Cody WL, Merrell DS, Hendrixson DR. Change is good: variations in common biological mechanisms in the epsilonproteobacterial genera Campylobacter and Helicobacter. Microbiol Mol Biol Rev 2011; 75:84-132. [PMID: 21372321 PMCID: PMC3063351 DOI: 10.1128/mmbr.00035-10] [Citation(s) in RCA: 67] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023] Open
Abstract
Microbial evolution and subsequent species diversification enable bacterial organisms to perform common biological processes by a variety of means. The epsilonproteobacteria are a diverse class of prokaryotes that thrive in diverse habitats. Many of these environmental niches are labeled as extreme, whereas other niches include various sites within human, animal, and insect hosts. Some epsilonproteobacteria, such as Campylobacter jejuni and Helicobacter pylori, are common pathogens of humans that inhabit specific regions of the gastrointestinal tract. As such, the biological processes of pathogenic Campylobacter and Helicobacter spp. are often modeled after those of common enteric pathogens such as Salmonella spp. and Escherichia coli. While many exquisite biological mechanisms involving biochemical processes, genetic regulatory pathways, and pathogenesis of disease have been elucidated from studies of Salmonella spp. and E. coli, these paradigms often do not apply to the same processes in the epsilonproteobacteria. Instead, these bacteria often display extensive variation in common biological mechanisms relative to those of other prototypical bacteria. In this review, five biological processes of commonly studied model bacterial species are compared to those of the epsilonproteobacteria C. jejuni and H. pylori. Distinct differences in the processes of flagellar biosynthesis, DNA uptake and recombination, iron homeostasis, interaction with epithelial cells, and protein glycosylation are highlighted. Collectively, these studies support a broader view of the vast repertoire of biological mechanisms employed by bacteria and suggest that future studies of the epsilonproteobacteria will continue to provide novel and interesting information regarding prokaryotic cellular biology.
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Affiliation(s)
- Jeremy J. Gilbreath
- Department of Microbiology and Immunology, Uniformed Services University of the Health Sciences, Bethesda, Maryland 20814, Department of Microbiology, University of Texas Southwestern Medical Center, Dallas, Texas 75390
| | - William L. Cody
- Department of Microbiology and Immunology, Uniformed Services University of the Health Sciences, Bethesda, Maryland 20814, Department of Microbiology, University of Texas Southwestern Medical Center, Dallas, Texas 75390
| | - D. Scott Merrell
- Department of Microbiology and Immunology, Uniformed Services University of the Health Sciences, Bethesda, Maryland 20814, Department of Microbiology, University of Texas Southwestern Medical Center, Dallas, Texas 75390
| | - David R. Hendrixson
- Department of Microbiology and Immunology, Uniformed Services University of the Health Sciences, Bethesda, Maryland 20814, Department of Microbiology, University of Texas Southwestern Medical Center, Dallas, Texas 75390
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Johnson M, Sengupta M, Purves J, Tarrant E, Williams PH, Cockayne A, Muthaiyan A, Stephenson R, Ledala N, Wilkinson BJ, Jayaswal RK, Morrissey JA. Fur is required for the activation of virulence gene expression through the induction of the sae regulatory system in Staphylococcus aureus. Int J Med Microbiol 2010; 301:44-52. [PMID: 20705504 DOI: 10.1016/j.ijmm.2010.05.003] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2009] [Revised: 02/26/2010] [Accepted: 05/09/2010] [Indexed: 01/05/2023] Open
Abstract
Our previous studies showed that both Sae and Fur are required for the induction of eap and emp expression in low iron. In this study, we show that expression of sae is also iron-regulated, as sae expression is activated by Fur in low iron. We also demonstrate that both Fur and Sae are required for full induction of the oxidative stress response and expression of non-covalently bound surface proteins in low-iron growth conditions. In addition, Sae is required for the induced expression of the important virulence factors isdA and isdB in low iron. Our studies also indicate that Fur is required for the induced expression of the global regulators Agr and Rot in low iron and a number of extracellular virulence factors such as the haemolysins which are also Sae- and Agr-regulated. Hence, we show that Fur is central to a complex regulatory network that is required for the induced expression of a number of important S. aureus virulence determinants in low iron.
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Affiliation(s)
- Miranda Johnson
- Dept. of Genetics, University of Leicester, University Road, Leicester LE1 7RH, UK
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Mutagenesis of conserved amino acids of Helicobacter pylori fur reveals residues important for function. J Bacteriol 2010; 192:5037-52. [PMID: 20644138 DOI: 10.1128/jb.00198-10] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
The ferric uptake regulator (Fur) of the medically important pathogen Helicobacter pylori is unique in that it has been shown to function as a repressor both in the presence of an Fe2+ cofactor and in its apo (non-Fe2+-bound) form. However, virtually nothing is known concerning the amino acid residues that are important for Fur functioning. Therefore, mutations in six conserved amino acid residues of H. pylori Fur were constructed and analyzed for their impact on both iron-bound and apo repression. In addition, accumulation of the mutant proteins, protein secondary structure, DNA binding ability, iron binding capacity, and the ability to form higher-order structures were also examined for each mutant protein. While none of the mutated residues completely abrogated the function of Fur, we were able to identify residues that were critical for both iron-bound and apo-Fur repression. One mutation, V64A, did not alter regulation of any target genes. However, each of the five remaining mutations showed an effect on either iron-bound or apo regulation. Of these, H96A, E110A, and E117A mutations altered iron-bound Fur regulation and were all shown to influence iron binding to different extents. Additionally, the H96A mutation was shown to alter Fur oligomerization, and the E110A mutation was shown to impact oligomerization and DNA binding. Conversely, the H134A mutant exhibited changes in apo-Fur regulation that were the result of alterations in DNA binding. Although the E90A mutant exhibited alterations in apo-Fur regulation, this mutation did not affect any of the assessed protein functions. This study is the first for H. pylori to analyze the roles of specific amino acid residues of Fur in function and continues to highlight the complexity of Fur regulation in this organism.
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Miles S, Carpenter BM, Gancz H, Merrell DS. Helicobacter pylori apo-Fur regulation appears unconserved across species. J Microbiol 2010; 48:378-86. [PMID: 20571957 DOI: 10.1007/s12275-010-0022-0] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2010] [Accepted: 02/08/2010] [Indexed: 11/30/2022]
Abstract
The Ferric Uptake Regulator (Fur) is a transcriptional regulator that is conserved across a broad number of bacterial species and has been shown to regulate expression of iron uptake and storage genes. Additionally, Fur has been shown to be an important colonization factor of the gastric pathogen Helicobacter pylori. In H. pylori, Fur-dependent regulation appears to be unique in that Fur is able to act as a transcriptional repressor when bound to iron as well as in its iron free (apo) form. To date, apo-regulation has not been identified in any other bacterium. To determine whether Fur from other species has the capacity for apo-regulation, we investigated the ability of Fur from Escherichia coli, Campylobacter jejuni, Desulfovibrio vulgaris Hildenborough, Pseudomonas aeruginosa, and Vibrio cholerae to complement both iron-bound and apo-Fur regulation within the context of a H. pylori fur mutant. We found that while some Fur species (E. coli, C. jejuni, and V. cholerae) complemented iron-bound regulation, apo-regulation was unable to be complemented by any of the examined species. These data suggest that despite the conservation among bacterial Fur proteins, H. pylori Fur contains unique structure/function features that make it novel in comparison to Fur from other species.
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Affiliation(s)
- Shana Miles
- Department of Microbiology and Immunology, Uniformed Services University of the Health Sciences, Bethesda, MD 20814, USA
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Deletion of a fur-like gene affects iron homeostasis and magnetosome formation in Magnetospirillum gryphiswaldense. J Bacteriol 2010; 192:4192-204. [PMID: 20562310 DOI: 10.1128/jb.00319-10] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Magnetotactic bacteria synthesize specific organelles, the magnetosomes, which are membrane-enveloped crystals of the magnetic mineral magnetite (Fe(3)O(4)). The biomineralization of magnetite involves the uptake and intracellular accumulation of large amounts of iron. However, it is not clear how iron uptake and biomineralization are regulated and balanced with the biochemical iron requirement and intracellular homeostasis. In this study, we identified and analyzed a homologue of the ferric uptake regulator Fur in Magnetospirillum gryphiswaldense, which was able to complement a fur mutant of Escherichia coli. A fur deletion mutant of M. gryphiswaldense biomineralized fewer and slightly smaller magnetite crystals than did the wild type. Although the total cellular iron accumulation of the mutant was decreased due to reduced magnetite biomineralization, it exhibited an increased level of free intracellular iron, which was bound mostly to a ferritin-like metabolite that was found significantly increased in Mössbauer spectra of the mutant. Compared to that of the wild type, growth of the fur mutant was impaired in the presence of paraquat and under aerobic conditions. Using a Fur titration assay and proteomic analysis, we identified constituents of the Fur regulon. Whereas the expression of most known magnetosome genes was unaffected in the fur mutant, we identified 14 proteins whose expression was altered between the mutant and the wild type, including five proteins whose genes constitute putative iron uptake systems. Our data demonstrate that Fur is a regulator involved in global iron homeostasis, which also affects magnetite biomineralization, probably by balancing the competing demands for biochemical iron supply and magnetite biomineralization.
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Built shallow to maintain homeostasis and persistent infection: insight into the transcriptional regulatory network of the gastric human pathogen Helicobacter pylori. PLoS Pathog 2010; 6:e1000938. [PMID: 20548942 PMCID: PMC2883586 DOI: 10.1371/journal.ppat.1000938] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
Transcriptional regulatory networks (TRNs) transduce environmental signals into coordinated output expression of the genome. Accordingly, they are central for the adaptation of bacteria to their living environments and in host-pathogen interactions. Few attempts have been made to describe a TRN for a human pathogen, because even in model organisms, such as Escherichia coli, the analysis is hindered by the large number of transcription factors involved. In light of the paucity of regulators, the gastric human pathogen Helicobacter pylori represents a very appealing system for understanding how bacterial TRNs are wired up to support infection in the host. Herein, we review and analyze the available molecular and "-omic" data in a coherent ensemble, including protein-DNA and protein-protein interactions relevant for transcriptional control of pathogenic responses. The analysis covers approximately 80% of the annotated H. pylori regulators, and provides to our knowledge the first in-depth description of a TRN for an important pathogen. The emerging picture indicates a shallow TRN, made of four main modules (origons) that process the physiological responses needed to colonize the gastric niche. Specific network motifs confer distinct transcriptional response dynamics to the TRN, while long regulatory cascades are absent. Rather than having a plethora of specialized regulators, the TRN of H. pylori appears to transduce separate environmental inputs by using different combinations of a small set of regulators.
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Danielli A, Scarlato V. Regulatory circuits in Helicobacter pylori : network motifs and regulators involved in metal-dependent responses. FEMS Microbiol Rev 2010; 34:738-52. [PMID: 20579104 DOI: 10.1111/j.1574-6976.2010.00233.x] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
The ability of Helicobacter pylori, one of the most successful human bacterial pathogens, to colonize the acidic gastric niche persistently, depends on the proper homeostasis of intracellular metal ions, needed as cofactors of essential metallo-proteins involved in acid acclimation, respiration and detoxification. This fundamental task is controlled at the transcriptional level mainly by the regulators Fur and NikR, involved in iron homeostasis and nickel response, respectively. Herein, we review the molecular mechanisms that underlie the activity of these key pleiotropic regulators. In addition, we will focus on their involvement in the transcriptional regulatory network of the bacterium, pinpointing a surprising complexity of network motifs that interconnects them and their gene targets. These motifs appear to confer versatile dynamics of metal-dependent responses by extensive horizontal connections between the regulators and feedback control of metal-cofactor availability.
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Olczak AA, Wang G, Maier RJ. Up-expression of NapA and other oxidative stress proteins is a compensatory response to loss of majorHelicobacter pyloristress resistance factors. Free Radic Res 2009; 39:1173-82. [PMID: 16298743 DOI: 10.1080/10715760500306729] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
Twenty-six Helicobacter pylori targeted mutant strains with deficiencies in oxidative stress combating proteins, including 12 double mutant strains were analyzed via physiological and proteomic approaches to distinguish the major expression changes caused by the mutations. Mutations were introduced into both a Mtz(S) and a Mtz(R) strain background. Most of the mutations caused increased growth sensitivity of the strains to oxygen, and they all exhibited clear compensatory up-expression of oxidative stress resistance proteins enabling survival of the bacterium. The most frequent up-expressed oxidative stress resistance factor (observed in 16 of the mutants) was the iron-sequestering protein NapA, linking iron sequestration with oxidative stress resistance. The up-expression of individual proteins in mutants ranged from 2 to 10 fold that of the wild type strain, even when incubated in a low O(2) environment. For example, a considerably higher level of catalase expression (4 fold of that in the wild-type strain) was observed in ahpC napA and ahpC sodB double mutants. A Fur mutant up-expressed ferritin (Pfr) protein 20-fold. In some mutant strains the bacterial DNA is protected from oxidative stress damage apparently via overexpression of oxidative stress-combating proteins such as NapA, catalase or MdaB (an NADPH quinone reductase). Our results show that H. pylori has a variety of ways to compensate for loss of major oxidative stress combating factors.
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Affiliation(s)
- Adriana A Olczak
- Department of Microbiology, University of Georgia, Athens, 30602, USA
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Vitale S, Fauquant C, Lascoux D, Schauer K, Saint-Pierre C, Michaud-Soret I. A ZnS4 Structural Zinc Site in the Helicobacter pylori Ferric Uptake Regulator. Biochemistry 2009; 48:5582-91. [DOI: 10.1021/bi9004396] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Affiliation(s)
- Sylvia Vitale
- CNRS UMR 5249 Laboratoire de Chimie et Biologie des Métaux, Commissariat à l’Energie Atomique (CEA), Direction des Sciences du Vivant (DSV), l’Institut de Recherches en Technologies et Sciences pour le Vivant (iRTSV), and Université Joseph Fourier, 17 rue des Martyrs, F-38054 Grenoble Cedex 9, France
| | - Caroline Fauquant
- CNRS UMR 5249 Laboratoire de Chimie et Biologie des Métaux, Commissariat à l’Energie Atomique (CEA), Direction des Sciences du Vivant (DSV), l’Institut de Recherches en Technologies et Sciences pour le Vivant (iRTSV), and Université Joseph Fourier, 17 rue des Martyrs, F-38054 Grenoble Cedex 9, France
| | - David Lascoux
- Laboratoire de Spectrométrie de Masse des Protéines, Institut de Biologie Structurale, Jean-Pierre Ebel (UMR 5075 CNRS/CEA/UJF), F-38027 Grenoble Cedex 1, France
| | - Kristine Schauer
- Unité Pathogenèse de Helicobacter, Institut Pasteur, 28 rue du Docteur Roux, 75724 Paris Cedex 15, France
| | - Christine Saint-Pierre
- Laboratoire des Lésions des Acides Nucléiques, DSM/INAC/Service de Chimie Inorganique et Biologique, UMR E-3 CEA/UJF CNRS FRE 3200, 17 rue des Martyrs, Grenoble F-38054 Cedex 9, France
| | - Isabelle Michaud-Soret
- CNRS UMR 5249 Laboratoire de Chimie et Biologie des Métaux, Commissariat à l’Energie Atomique (CEA), Direction des Sciences du Vivant (DSV), l’Institut de Recherches en Technologies et Sciences pour le Vivant (iRTSV), and Université Joseph Fourier, 17 rue des Martyrs, F-38054 Grenoble Cedex 9, France
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This is not your mother's repressor: the complex role of fur in pathogenesis. Infect Immun 2009; 77:2590-601. [PMID: 19364842 DOI: 10.1128/iai.00116-09] [Citation(s) in RCA: 166] [Impact Index Per Article: 11.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
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Guo Y, Guo G, Mao X, Zhang W, Xiao J, Tong W, Liu T, Xiao B, Liu X, Feng Y, Zou Q. Functional identification of HugZ, a heme oxygenase from Helicobacter pylori. BMC Microbiol 2008; 8:226. [PMID: 19091096 PMCID: PMC2644699 DOI: 10.1186/1471-2180-8-226] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2008] [Accepted: 12/17/2008] [Indexed: 11/17/2022] Open
Abstract
Background Iron is recognized as an important trace element, essential for most organisms including pathogenic bacteria. HugZ, a protein related to heme iron utilization, is involved in bacterial acquisition of iron from the host. We previously observed that a hugZ homologue is correlated with the adaptive colonization of Helicobacter pylori (H. pylori), a major gastro-enteric pathogen. However, its exact physiological role remains unclear. Results A gene homologous to hugZ, designated hp0318, identified in H. pylori ATCC 26695, exhibits 66% similarity to cj1613c of Campylobacter jejuni NCTC 11168. Soluble 6 × His fused-HugZ protein was expressed in vitro. Hemin-agrose affinity analysis indicated that the recombinant HugZ protein can bind to hemin. Absorption spectroscopy at 411 nm further revealed a heme:HugZ binding ratio of 1:1. Enzymatic assays showed that purified recombinant HugZ protein can degrade hemin into biliverdin and carbon monoxide in the presence of either ascorbic acid or NADPH and cytochrome P450 reductase. The biochemical and enzymatic characteristics agreed closely with those of Campylobacter jejuni Cj1613c protein, implying that hp0318 is a functional member of the HugZ family. A hugZ deletion mutant was obtained by homologous recombination. This mutant strain showed poor growth when hemoglobin was provided as the source of iron, partly because of its failure to utilize hemoglobin efficiently. Real-time quantitative PCR also confirmed that the expression of hugZ was regulated by iron levels. Conclusion These findings provide biochemical and genetic evidence that hugZ (hp0318) encodes a heme oxygenase involved in iron release/uptake in H. pylori.
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Affiliation(s)
- Ying Guo
- Department of Clinical Microbiology and Immunology, College of Medical Laboratory, Third Military Medical University, Chongqing, PR China.
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Stoof J, Breijer S, Pot RGJ, van der Neut D, Kuipers EJ, Kusters JG, van Vliet AHM. Inverse nickel-responsive regulation of two urease enzymes in the gastric pathogen Helicobacter mustelae. Environ Microbiol 2008; 10:2586-97. [PMID: 18564183 DOI: 10.1111/j.1462-2920.2008.01681.x] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
The acidic gastric environment of mammals can be chronically colonized by pathogenic Helicobacter species, which use the nickel-dependent urea-degrading enzyme urease to confer acid resistance. Nickel availability in the mammal host is low, being mostly restricted to vegetarian dietary sources, and thus Helicobacter species colonizing carnivores may be subjected to episodes of nickel deficiency and associated acid sensitivity. The aim of this study was to investigate how these Helicobacter species have adapted to the nickel-restricted diet of their carnivorous host. Three carnivore-colonizing Helicobacter species express a second functional urea-degrading urease enzyme (UreA2B2), which functions as adaptation to nickel deficiency. UreA2B2 was not detected in seven other Helicobacter species, and is in Helicobacter mustelae only expressed in nickel-restricted conditions, and its expression was higher in iron-rich conditions. In contrast to the standard urease UreAB, UreA2B2 does not require activation by urease or hydrogenase accessory proteins, which mediate nickel incorporation into these enzymes. Activity of either UreAB or UreA2B2 urease allowed survival of a severe acid shock in the presence of urea, demonstrating a functional role for UreA2B2 in acid resistance. Pathogens often express colonization factors which are adapted to their host. The UreA2B2 urease could represent an example of pathogen adaptation to the specifics of the diet of their carnivorous host, rather than to the host itself.
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Affiliation(s)
- Jeroen Stoof
- Department of Gastroenterology and Hepatology, Erasmus MC - University Medical Center, 's Gravendijkwal 230, 3015 CE Rotterdam, the Netherlands
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Iron-regulated biofilm formation in Staphylococcus aureus Newman requires ica and the secreted protein Emp. Infect Immun 2008; 76:1756-65. [PMID: 18268030 DOI: 10.1128/iai.01635-07] [Citation(s) in RCA: 81] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023] Open
Abstract
Staphylococcus aureus biofilm formation is induced in iron-restricted growth conditions in vitro. In this study, we showed that Emp and Eap play important roles in low-iron-induced biofilm formation of S. aureus Newman. Eap and Emp are secreted proteins which are non-covalently attached to the S. aureus cell surface and have previously been implicated in a number of aspects of S. aureus pathogenesis. We showed here that the transcription of these important virulence factors is induced by growth in low-iron medium, reflective of the in vivo environment. Our results show that iron regulation of Eap and Emp is Fur independent. However, Fur is required for full induction of eap and emp expression in low-iron conditions. In this study, we demonstrated that in addition to Fur, low-iron-induced biofilm formation requires Sae, Agr, and SarA. In iron-restricted growth conditions, Sae and Agr are essential for Emp and Eap expression and hence for biofilm formation, whereas SarA appears to have a less-significant role. We also showed that expression of the ica operon is required for biofilm formation in iron-restricted growth conditions. We demonstrated that in fact, ica is required for the expression of the important multifunctional virulence determinants eap and emp.
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Shao C, Zhang Q, Sun Y, Liu Z, Zeng J, Zhou Y, Yu X, Jia J. Helicobacter pylori protein response to human bile stress. J Med Microbiol 2008; 57:151-158. [DOI: 10.1099/jmm.0.47616-0] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The ability of Helicobacter pylori to tolerate bile is likely to be important for its colonization and survival in the gastrointestinal tract of humans. As bile can be acidified after reflux into the low pH of the human stomach, the inhibitory effect of fresh human bile with normal appearance on H. pylori before and after acidification was tested first. The results showed that acidification of bile attenuated its inhibitory activity towards H. pylori. Next, the protein profiles of H. pylori under human bile and acidified bile stress were obtained by two-dimensional electrophoresis. Protein spots with differential expression were identified using tandem matrix-assisted laser desorption/ionization time-of-flight mass spectrometry. The results showed that the changes in proteomic profiles under bile and acidified bile stress were similar when compared with that of normal H. pylori. Expression of 28 proteins was found to be modulated, with the majority being induced during bile or acidified bile exposure. These proteins included molecular chaperones, proteins involved in iron storage, chemotaxis protein, enzymes related to energy metabolism and flagellar protein. These results indicate that H. pylori responds to bile and acidified bile stress through multiple mechanisms involving many signalling pathways.
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Affiliation(s)
- Chunhong Shao
- Department of Microbiology, School of Medicine, Shandong University, 44 Wenhuaxi Road, Jinan, Shandong 250012, PR China
| | - Qunye Zhang
- Key Lab for Experimental Teratology of Chinese Ministry of Education, School of Medicine, Shandong University, Jinan, Shandong 250012, PR China
| | - Yundong Sun
- Department of Microbiology, School of Medicine, Shandong University, 44 Wenhuaxi Road, Jinan, Shandong 250012, PR China
| | - Zhifang Liu
- Department of Biochemistry, School of Medicine, Shandong University, Jinan, Shandong 250012, PR China
| | - Jiping Zeng
- Department of Biochemistry, School of Medicine, Shandong University, Jinan, Shandong 250012, PR China
| | - Yabin Zhou
- Key Lab for Experimental Teratology of Chinese Ministry of Education, School of Medicine, Shandong University, Jinan, Shandong 250012, PR China
- Department of Microbiology, School of Medicine, Shandong University, 44 Wenhuaxi Road, Jinan, Shandong 250012, PR China
| | - Xiuping Yu
- Key Lab for Experimental Teratology of Chinese Ministry of Education, School of Medicine, Shandong University, Jinan, Shandong 250012, PR China
- Department of Microbiology, School of Medicine, Shandong University, 44 Wenhuaxi Road, Jinan, Shandong 250012, PR China
| | - Jihui Jia
- Key Lab for Experimental Teratology of Chinese Ministry of Education, School of Medicine, Shandong University, Jinan, Shandong 250012, PR China
- Department of Microbiology, School of Medicine, Shandong University, 44 Wenhuaxi Road, Jinan, Shandong 250012, PR China
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The iron stimulon of Xylella fastidiosa includes genes for type IV pilus and colicin V-like bacteriocins. J Bacteriol 2008; 190:2368-78. [PMID: 18223091 DOI: 10.1128/jb.01495-07] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
Xylella fastidiosa is the etiologic agent of a wide range of plant diseases, including citrus variegated chlorosis (CVC), a major threat to citrus industry. The genomes of several strains of this phytopathogen were completely sequenced, enabling large-scale functional studies. DNA microarrays representing 2,608 (91.6%) coding sequences (CDS) of X. fastidiosa CVC strain 9a5c were used to investigate transcript levels during growth with different iron availabilities. When treated with the iron chelator 2,2'-dipyridyl, 193 CDS were considered up-regulated and 216 were considered down-regulated. Upon incubation with 100 microM ferric pyrophosphate, 218 and 256 CDS were considered up- and down-regulated, respectively. Differential expression for a subset of 44 CDS was further evaluated by reverse transcription-quantitative PCR. Several CDS involved with regulatory functions, pathogenicity, and cell structure were modulated under both conditions assayed, suggesting that major changes in cell architecture and metabolism occur when X. fastidiosa cells are exposed to extreme variations in iron concentration. Interestingly, the modulated CDS include those related to colicin V-like bacteriocin synthesis and secretion and to functions of pili/fimbriae. We also investigated the contribution of the ferric uptake regulator Fur to the iron stimulon of X. fastidiosa. The promoter regions of the strain 9a5c genome were screened for putative Fur boxes, and candidates were analyzed by electrophoretic mobility shift assays. Taken together, our data support the hypothesis that Fur is not solely responsible for the modulation of the iron stimulon of X. fastidiosa, and they present novel evidence for iron regulation of pathogenicity determinants.
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Velayudhan J, Castor M, Richardson A, Main-Hester KL, Fang FC. The role of ferritins in the physiology of Salmonella enterica sv. Typhimurium: a unique role for ferritin B in iron-sulphur cluster repair and virulence. Mol Microbiol 2007; 63:1495-507. [PMID: 17302823 DOI: 10.1111/j.1365-2958.2007.05600.x] [Citation(s) in RCA: 110] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
Ferritins are ubiquitous iron (Fe) storage proteins that play a fundamental role in cellular Fe homeostasis. The enteric pathogen Salmonella enterica serovar Typhimurium possesses four ferritins: bacterioferritin, ferritin A, ferritin B and Dps. The haem-containing bacterioferritin (Bfr) accounts for the majority of stored Fe, followed by ferritin A (FtnA). Inactivation of bfr elevates the intracellular free Fe concentration and enhances susceptibility to H2O2 stress. The DNA-binding Dps protein provides protection from oxidative damage without affecting the steady-state intracellular free Fe concentration. FtnB appears to be particularly important for the repair of oxidatively damaged Fe-sulphur clusters of aconitase and, in contrast to Bfr and FtnA, is required for Salmonella virulence in mice. Moreover, ftnB and dps are repressed by the Fe-responsive regulator Fur and induced under conditions of Fe limitation, whereas bfr and ftnA are maximally expressed when Fe is abundant. The absence of a conserved ferroxidase domain and the potentiation of oxidative stress by FtnB in some strains lacking Dps suggest that FtnB serves as a facile cellular reservoir of Fe2+.
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Affiliation(s)
- Jyoti Velayudhan
- Department of Laboratory Medicine, University of Washington School of Medicine, Seattle, WA 98195, USA
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de Reuse H, Bereswill S. Ten years after the first Helicobacter pylori genome: comparative and functional genomics provide new insights in the variability and adaptability of a persistent pathogen. ACTA ACUST UNITED AC 2007; 50:165-76. [PMID: 17567280 DOI: 10.1111/j.1574-695x.2007.00244.x] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Abstract
In this review, we summarize how genomic approaches contributed to the understanding of the biology of the recently discovered pathogen Helicobacter pylori. Comparative genomics provided new insights into H. pylori's spectacular genetic diversity and generated exiting hypotheses on its evolutionary history. Transcriptomic studies provided original information on the mechanisms of H. pylori gastric adaptation that are central to its virulence.
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Affiliation(s)
- Hilde de Reuse
- Institut Pasteur, Unité de Pathogénie Bacterienne des Muqueuses, Paris, France
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