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Brunson DN, Lemos JA. Heme utilization by the enterococci. FEMS MICROBES 2024; 5:xtae019. [PMID: 39070772 PMCID: PMC11282960 DOI: 10.1093/femsmc/xtae019] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2024] [Revised: 06/02/2024] [Accepted: 07/01/2024] [Indexed: 07/30/2024] Open
Abstract
Heme consists of a tetrapyrrole ring ligating an iron ion and has important roles in biological systems. While well-known as the oxygen-binding molecule within hemoglobin of mammals, heme is also cofactor for several enzymes and a major iron source for bacteria within the host. The enterococci are a diverse group of Gram-positive bacteria that exist primarily within the gastrointestinal tract of animals. However, some species within this genus can transform into formidable opportunistic pathogens, largely owing to their extraordinary adaptability to hostile environments. Although enterococci cannot synthesize heme nor depend on heme to grow, several species within the genus encode proteins that utilize heme as a cofactor, which appears to increase their fitness and ability to thrive in challenging environments. This includes more efficient energy generation via aerobic respiration and protection from reactive oxygen species. Here, we review the significance of heme to enterococci, primarily the major human pathogen Enterococcus faecalis, use bioinformatics to assess the prevalence of hemoproteins throughout the genus, and highlight recent studies that underscore the central role of the heme-E. faecalis relationship in host-pathogen dynamics and interspecies bacterial interactions.
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Affiliation(s)
- Debra N Brunson
- Department of Oral Biology, University of Florida College of Dentistry, 1395 Center Drive, Gainesville, FL 32610, United States
| | - José A Lemos
- Department of Oral Biology, University of Florida College of Dentistry, 1395 Center Drive, Gainesville, FL 32610, United States
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2
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Lê-Bury P, Echenique-Rivera H, Pizarro-Cerdá J, Dussurget O. Determinants of bacterial survival and proliferation in blood. FEMS Microbiol Rev 2024; 48:fuae013. [PMID: 38734892 PMCID: PMC11163986 DOI: 10.1093/femsre/fuae013] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2023] [Revised: 04/29/2024] [Accepted: 05/10/2024] [Indexed: 05/13/2024] Open
Abstract
Bloodstream infection is a major public health concern associated with high mortality and high healthcare costs worldwide. Bacteremia can trigger fatal sepsis whose prevention, diagnosis, and management have been recognized as a global health priority by the World Health Organization. Additionally, infection control is increasingly threatened by antimicrobial resistance, which is the focus of global action plans in the framework of a One Health response. In-depth knowledge of the infection process is needed to develop efficient preventive and therapeutic measures. The pathogenesis of bloodstream infection is a dynamic process resulting from the invasion of the vascular system by bacteria, which finely regulate their metabolic pathways and virulence factors to overcome the blood immune defenses and proliferate. In this review, we highlight our current understanding of determinants of bacterial survival and proliferation in the bloodstream and discuss their interactions with the molecular and cellular components of blood.
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Affiliation(s)
- Pierre Lê-Bury
- Institut Pasteur, Université Paris Cité, CNRS UMR6047, Yersinia Research Unit, 28 rue du Dr Roux, 75015 Paris, France
- Université Paris-Saclay, Inserm, CEA, Center for Immunology of Viral, Autoimmune, Hematological and Bacterial Diseases (IMVA-HB/IDMIT), 18 route du Panorama, 92260 Fontenay-aux-Roses, France
| | - Hebert Echenique-Rivera
- Institut Pasteur, Université Paris Cité, CNRS UMR6047, Yersinia Research Unit, 28 rue du Dr Roux, 75015 Paris, France
| | - Javier Pizarro-Cerdá
- Institut Pasteur, Université Paris Cité, CNRS UMR6047, Yersinia Research Unit, 28 rue du Dr Roux, 75015 Paris, France
- Institut Pasteur, Université Paris Cité, Yersinia National Reference Laboratory, WHO Collaborating Research & Reference Centre for Plague FRA-146, 28 rue du Dr Roux, 75015 Paris, France
| | - Olivier Dussurget
- Institut Pasteur, Université Paris Cité, CNRS UMR6047, Yersinia Research Unit, 28 rue du Dr Roux, 75015 Paris, France
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Cozzi M, Failla M, Gianquinto E, Kovachka S, Buoli Comani V, Compari C, De Bei O, Giaccari R, Marchesani F, Marchetti M, Ronda L, Rolando B, Baroni M, Cruciani G, Campanini B, Bettati S, Faggiano S, Lazzarato L, Spyrakis F. Identification of small molecules affecting the interaction between human hemoglobin and Staphylococcus aureus IsdB hemophore. Sci Rep 2024; 14:8272. [PMID: 38594253 PMCID: PMC11003968 DOI: 10.1038/s41598-024-55931-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2023] [Accepted: 02/29/2024] [Indexed: 04/11/2024] Open
Abstract
Human hemoglobin (Hb) is the preferred iron source of Staphylococcus aureus. This pathogenic bacterium exploits a sophisticated protein machinery called Iron-regulated surface determinant (Isd) system to bind Hb, extract and internalize heme, and finally degrade it to complete iron acquisition. IsdB, the surface exposed Hb receptor, is a proven virulence factor of S. aureus and the inhibition of its interaction with Hb can be pursued as a strategy to develop new classes of antimicrobials. To identify small molecules able to disrupt IsdB:Hb protein-protein interactions (PPIs), we carried out a structure-based virtual screening campaign and developed an ad hoc immunoassay to screen the retrieved set of commercially available compounds. Saturation-transfer difference (STD) NMR was applied to verify specific interactions of a sub-set of molecules, chosen based on their efficacy in reducing the amount of Hb bound to IsdB. Among molecules for which direct binding was verified, the best hit was submitted to ITC analysis to measure the binding affinity to Hb, which was found to be in the low micromolar range. The results demonstrate the viability of the proposed in silico/in vitro experimental pipeline to discover and test IsdB:Hb PPI inhibitors. The identified lead compound will be the starting point for future SAR and molecule optimization campaigns.
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Affiliation(s)
- Monica Cozzi
- Department of Food and Drug, University of Parma, Parma, Italy
| | | | - Eleonora Gianquinto
- Department of Drug Science and Technology, University of Turin, Turin, Italy
| | - Sandra Kovachka
- Department of Drug Science and Technology, University of Turin, Turin, Italy
- The Herbert Wertheim UF Scripps Institute for Biomedical Innovation & Technology, Jupiter, FL, USA
| | | | | | - Omar De Bei
- Department of Medicine and Surgery, University of Parma, Parma, Italy
| | | | | | | | - Luca Ronda
- Department of Medicine and Surgery, University of Parma, Parma, Italy
- Institute of Biophysics, National Research Council, Pisa, Italy
| | - Barbara Rolando
- Department of Drug Science and Technology, University of Turin, Turin, Italy
| | - Massimo Baroni
- Molecular Discovery Ltd, Kisnetic Business Centre, Elstree, Borehamwood, Hertfordshire, UK
| | - Gabriele Cruciani
- Department of Chemistry, Biology and Biotechnology, University of Perugia, Perugia, Italy
| | | | - Stefano Bettati
- Department of Medicine and Surgery, University of Parma, Parma, Italy
- Institute of Biophysics, National Research Council, Pisa, Italy
| | - Serena Faggiano
- Department of Food and Drug, University of Parma, Parma, Italy.
- Institute of Biophysics, National Research Council, Pisa, Italy.
| | - Loretta Lazzarato
- Department of Drug Science and Technology, University of Turin, Turin, Italy
| | - Francesca Spyrakis
- Department of Drug Science and Technology, University of Turin, Turin, Italy.
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4
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Botti V, De Bei O, Marchetti M, Campanini B, Cannistraro S, Bettati S, Bizzarri AR. Nanoscale dynamical investigation of the hemoglobin complex with the bacterial protein IsdB: is their interaction stabilized by catch bonds? NANOSCALE 2024; 16:4308-4316. [PMID: 38353599 DOI: 10.1039/d3nr05241a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/23/2024]
Abstract
Iron-regulated surface determinant B (IsdB) is a surface protein of Staphylococcus aureus that plays essential roles in host cell invasion by mediating both bacterial adhesion and hemic iron acquisition. Single-molecule experiments have recently revealed that the binding of IsdB to vitronectin and integrins is dramatically strengthened under mechanical stress conditions, promoting staphylococcal adhesion. Here we conducted atomic force spectroscopy (AFS) measurements of the interaction between IsdB and hemoglobin (Hb), in both its oxidized (metHb) and reduced forms (HbCO). While the former represents the natural substrate for IsdB, the latter is resistant to heme extraction. For the unbinding between IsdB and HbCO, we obtained a linear trend in the Bell-Evans plot, indicative of a weakening of the interaction upon mechanical stress. For the unbinding between IsdB and metHb, we found similar behavior at low loading rates. Remarkably, a non-linear trend of the complex interaction force was detected at higher force-pulling rates. Such behavior may provide some cues to the ability of IsdB to form stress-dependent bonds also with Hb, possibly enabling a more efficient heme transfer through stabilization of the transient (in vivo) IsdB-Hb complex.
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Affiliation(s)
- Valentina Botti
- Biophysics and Nanoscience Centre, DEB, Università della Tuscia, Largo dell'Università, 01100, Viterbo, Italy.
| | - Omar De Bei
- Department of Medicine and Surgery, University of Parma, Via Volturno 39, 43125, Parma, Italy.
| | - Marialaura Marchetti
- Department of Medicine and Surgery, University of Parma, Via Volturno 39, 43125, Parma, Italy.
| | - Barbara Campanini
- Department of Food and Drug, University of Parma, Parco Area delle Scienze 23/A, 43124, Parma, Italy
| | - Salvatore Cannistraro
- Biophysics and Nanoscience Centre, DEB, Università della Tuscia, Largo dell'Università, 01100, Viterbo, Italy.
| | - Stefano Bettati
- Department of Medicine and Surgery, University of Parma, Via Volturno 39, 43125, Parma, Italy.
- Institute of Biophysics, National Research Council, via G. Moruzzi, 56124, Pisa, Italy
| | - Anna Rita Bizzarri
- Biophysics and Nanoscience Centre, DEB, Università della Tuscia, Largo dell'Università, 01100, Viterbo, Italy.
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Hsieh RC, Liu R, Burgin DJ, Otto M. Understanding mechanisms of virulence in MRSA: implications for antivirulence treatment strategies. Expert Rev Anti Infect Ther 2023; 21:911-928. [PMID: 37501364 DOI: 10.1080/14787210.2023.2242585] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2023] [Accepted: 07/26/2023] [Indexed: 07/29/2023]
Abstract
INTRODUCTION Methicillin-resistant Staphylococcus aureus (MRSA) is a widespread pathogen, often causing recurrent and deadly infections in the hospital and community. Many S. aureus virulence factors have been suggested as potential targets for antivirulence therapy to decrease the threat of diminishing antibiotic availability. Antivirulence methods hold promise due to their adjunctive and prophylactic potential and decreased risk for selective pressure. AREAS COVERED This review describes the dominant virulence mechanisms exerted by MRSA and antivirulence therapeutics that are currently undergoing testing in clinical or preclinical stages. We also discuss the advantages and downsides of several investigational antivirulence approaches, including the targeting of bacterial transporters, host-directed therapy, and quorum-sensing inhibitors. For this review, a systematic search of literature on PubMed, Google Scholar, and Web of Science for relevant search terms was performed in April and May 2023. EXPERT OPINION Vaccine and antibody strategies have failed in clinical trials and could benefit from more basic science-informed approaches. Antivirulence-targeting approaches need to be set up better to meet the requirements of drug development, rather than only providing limited results to provide 'proof-of-principle' translational value of pathogenesis research. Nevertheless, there is great potential of such strategies and potential particular promise for novel probiotic approaches.
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Affiliation(s)
- Roger C Hsieh
- Pathogen Molecular Genetics Section, Laboratory of Bacteriology, National Institute of Allergy and Infectious Diseases (NIAID), U.S. National Institutes of Health (NIH), Bethesda, Maryland, USA
| | - Ryan Liu
- Pathogen Molecular Genetics Section, Laboratory of Bacteriology, National Institute of Allergy and Infectious Diseases (NIAID), U.S. National Institutes of Health (NIH), Bethesda, Maryland, USA
| | - Dylan J Burgin
- Pathogen Molecular Genetics Section, Laboratory of Bacteriology, National Institute of Allergy and Infectious Diseases (NIAID), U.S. National Institutes of Health (NIH), Bethesda, Maryland, USA
| | - Michael Otto
- Pathogen Molecular Genetics Section, Laboratory of Bacteriology, National Institute of Allergy and Infectious Diseases (NIAID), U.S. National Institutes of Health (NIH), Bethesda, Maryland, USA
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Wang B, Dong Y, Cen Y, Chen S, Wen X, Liu K, Wu S, Yu L, Yu Y, Zhu Z, Ma J, Song B, Cui Y. PEI-PLGA nanoparticles significantly enhanced the immunogenicity of IsdB 137-361 proteins from Staphylococcus aureus. Immun Inflamm Dis 2023; 11:e928. [PMID: 37506158 PMCID: PMC10336661 DOI: 10.1002/iid3.928] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2023] [Revised: 05/30/2023] [Accepted: 06/17/2023] [Indexed: 07/30/2023] Open
Abstract
INTRODUCTION Staphylococcus aureus seriously threatens human and animal health. IsdB137-361 of the iron surface determinant B protein (IsdB) from S. aureus exhibits the strong immunogenicity, but its immunoprotective effect is still to be further promoted. Because PEI-PLGA nanoparticles are generated by PEI conjugate with PLGA to develop great potential as a novel immune adjuvant, the immunogenicity of IsdB137-361 is likely be strengthened by PEI-PLGA. METHODS Here, PEI-PLGA nanoparticles containing IsdB137-361 proteins were prepared by optimizing the entrapment efficiency. Mice were immunized with IsdB137-361 -PEI-PLGA nanoparticles to assess their anti-S. aureus effects. The level of IFN-γ, IL-4, IL-17, and IL-10 cytokines from spleen lymphocytes in mice and generation of the antibodies against IsdB137-361 in serum was assessed by ELISA, the protective immune response was appraised by S. aureus challenge. RESULTS IsdB137-361 proteins loaded by PEI-PLGA were able to stimulate effectively the proliferation of spleen lymphocytes and increase the secretion of IFN-γ, IL-4, IL-17, and IL-10 cytokine from spleen lymphocytes, and significantly enhance generation of the antibodies against IsdB137-361 in serum, reduce the level of bacterial load in liver, spleen and kidney, and greatly improve the survival rate of mice after challenge. CONCLUSION These data showed that PEI-PLGA nanoparticles can significantly enhance the immunogenicity of IsdB137-361 proteins, and provide an important reference for the development of novel immune adjuvant.
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Affiliation(s)
- Beiyan Wang
- College of Life Science and Technology, Heilongjiang Bayi Agricultural University, Daqing, China
| | - Yazun Dong
- College of Life Science and Technology, Heilongjiang Bayi Agricultural University, Daqing, China
| | - Yuwei Cen
- College of Life Science and Technology, Heilongjiang Bayi Agricultural University, Daqing, China
| | - Shujie Chen
- College of Life Science and Technology, Heilongjiang Bayi Agricultural University, Daqing, China
| | - Xue Wen
- Water Environmental Protection Research Institute of Daqing Oilfield Water Company, Daqing, China
| | - Kaiyue Liu
- College of Life Science and Technology, Heilongjiang Bayi Agricultural University, Daqing, China
| | - Shuangshuang Wu
- College of Life Science and Technology, Heilongjiang Bayi Agricultural University, Daqing, China
| | - Liquan Yu
- College of Life Science and Technology, Heilongjiang Bayi Agricultural University, Daqing, China
| | - Yongzhong Yu
- College of Life Science and Technology, Heilongjiang Bayi Agricultural University, Daqing, China
| | - Zhanbo Zhu
- College of Animal Science and Veterinary Medicine, Heilongjiang Bayi Agricultural University, Daqing, China
| | - Jinzhu Ma
- College of Life Science and Technology, Heilongjiang Bayi Agricultural University, Daqing, China
| | - Baifen Song
- Key Laboratory of Animal Epidemiology and Zoonosis, College of Veterinary Medicine, China Agricul-tural University, Beijing, China
| | - Yudong Cui
- College of Life Science and Technology, Heilongjiang Bayi Agricultural University, Daqing, China
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Snoussi M, Noumi E, Bouali N, Bazaid AS, Alreshidi MM, Altayb HN, Chaieb K. Antibiotic Susceptibility Profiling of Human Pathogenic Staphylococcus aureus Strains Using Whole Genome Sequencing and Genome-Scale Annotation Approaches. Microorganisms 2023; 11:1124. [PMID: 37317098 DOI: 10.3390/microorganisms11051124] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2023] [Revised: 04/22/2023] [Accepted: 04/24/2023] [Indexed: 06/16/2023] Open
Abstract
Staphylococcus species are major pathogens with increasing importance due to the rise in antibiotic resistance. Whole genome sequencing and genome-scale annotation are promising approaches to study the pathogenicity and dissemination of virulence factors in nosocomial methicillin-resistant and multidrug-resistant bacteria in intensive care units. Draft genome sequences of eight clinical S. aureus strains were assembled and annotated for the prediction of antimicrobial resistance genes, virulence factors, and phylogenetic analysis. Most of the studied S. aureus strains displayed multi-resistance toward the tested drugs, reaching more than seven drugs up to 12 in isolate S22. The mecA gene was detected in three isolates (S14, S21, and S23), mecC was identified in S8 and S9, and blaZ was commonly identified in all isolates except strain S23. Additionally, two complete mobile genomic islands coding for methicillin resistance SCCmec Iva (2B) were identified in strains S21 and S23. Numerous antimicrobial resistance genes (norA, norC, MgrA, tet(45), APH(3')-IIIa, and AAC(6')-APH(2″)) were identified in chromosomes of different strains. Plasmid analysis revealed the presence of blaZ, tetK, and ermC in different plasmid types, located in gene cassettes containing plasmid replicons (rep) and insertion sequences (IS). Additionally, the aminoglycoside-resistant determinants were identified in S1 (APH(3')-IIIa), while AAC(6)-APH(2″) was detected in strains S8 and S14. The trimethoprim (dfrC) resistance gene was detected in S. aureus S21, and the fosfomycin (fosB) resistance gene was detected only in S. aureus S14. We also noted that S. aureus S1 belongs to ST1-t127, which has been reported as one of the most frequent human pathogen types. Additionally, we noted the presence of rare plasmid-mediated mecC-MRSA in some of our isolates.
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Affiliation(s)
- Mejdi Snoussi
- Department of Biology, College of Science, University of Ha'il, Ha'il P.O. Box 2440, Saudi Arabia
- Medical and Diagnostic Research Centre, University of Ha'il, Ha'il 55473, Saudi Arabia
| | - Emira Noumi
- Department of Biology, College of Science, University of Ha'il, Ha'il P.O. Box 2440, Saudi Arabia
- Medical and Diagnostic Research Centre, University of Ha'il, Ha'il 55473, Saudi Arabia
| | - Nouha Bouali
- Department of Biology, College of Science, University of Ha'il, Ha'il P.O. Box 2440, Saudi Arabia
- Medical and Diagnostic Research Centre, University of Ha'il, Ha'il 55473, Saudi Arabia
| | - Abdulrahman S Bazaid
- Department of Medical, Laboratory Science, College of Applied Medical Sciences, University of Ha'il, Ha'il 55476, Saudi Arabia
| | - Mousa M Alreshidi
- Department of Biology, College of Science, University of Ha'il, Ha'il P.O. Box 2440, Saudi Arabia
- Medical and Diagnostic Research Centre, University of Ha'il, Ha'il 55473, Saudi Arabia
| | - Hisham N Altayb
- Department of Biochemistry, Faculty of Science, King Abdulaziz University, Jeddah 21589, Saudi Arabia
- Center of Artificial Intelligence in Precision Medicines, King Abdulaziz University, Jeddah 21589, Saudi Arabia
| | - Kamel Chaieb
- Department of Biochemistry, Faculty of Science, King Abdulaziz University, Jeddah 21589, Saudi Arabia
- Laboratory of Analysis, Treatment and Valorization of Pollutants of the Environmental and Products, Faculty of Pharmacy, University of Monastir, Monastir 5000, Tunisia
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8
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Analysis of the HbpA Protein from Corynebacterium diphtheriae Clinical Isolates and Identification of a Putative Hemoglobin-Binding Site on HbpA. J Bacteriol 2022; 204:e0034922. [PMID: 36346227 PMCID: PMC9765017 DOI: 10.1128/jb.00349-22] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
The Corynebacterium diphtheriae hemoglobin-binding protein HbpA is critical for the acquisition of iron from the hemoglobin-haptoglobin complex (Hb-Hp). Previous studies using C. diphtheriae strain 1737 showed that large aggregates formed by HbpA are associated with iron transport activity and enhanced binding to Hb-Hp; however, specific regions within HbpA required for Hb-Hp binding or iron uptake have not been identified. In this study, we characterized two clinical isolates from Austria, designated 07-18 and 09-15, which express HbpA proteins that share only 53% and 44% sequence identity, respectively, to the strain 1737 HbpA protein. The HbpA proteins expressed by the Austrian strains had functional and structural properties similar to those of the HbpA protein in strain 1737 despite the limited sequence similarity. These shared characteristics between the HbpA proteins included similar cellular localization, aggregate formation, and Hb and Hb-Hp binding. Additionally, the Austrian strains were able to acquire iron from Hb and Hb-Hp, and deletion of the hbpA gene from these two clinical isolates reduced their ability to use Hb-Hp as an iron source. A sequence comparison between the HbpA proteins from 1737 and the Austrian strains assisted in the identification of a putative Hb-binding site that shared similar characteristics with the Hb-binding regions in Staphylococcus aureus NEAT domains. Amino acid substitutions within this conserved Hb-binding region significantly reduced Hb and Hb-Hp binding and diminished the hemin-iron uptake function of HbpA. These findings represent important advances in our understanding of the interaction of HbpA with human hemoproteins. IMPORTANCE Hemoglobin (Hb) is the primary source of iron in humans, and the acquisition of hemin-iron from Hb is critical for many bacterial pathogens to infect and survive in the human host. In this study, we have examined the C. diphtheriae Hb-binding protein HbpA in two clinical isolates and show that these proteins, despite limited sequence similarity, are functionally equivalent to the previously described HbpA protein in strain 1737. A sequence comparison between these three strains led to the identification of a conserved Hb-binding site, which will further our understanding of how this novel protein functions in hemin-iron transport and, more generally, will expand our knowledge on how Hb interacts with proteins.
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9
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Murdoch CC, Skaar EP. Nutritional immunity: the battle for nutrient metals at the host-pathogen interface. Nat Rev Microbiol 2022; 20:657-670. [PMID: 35641670 PMCID: PMC9153222 DOI: 10.1038/s41579-022-00745-6] [Citation(s) in RCA: 166] [Impact Index Per Article: 83.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/04/2022] [Indexed: 12/21/2022]
Abstract
Trace metals are essential micronutrients required for survival across all kingdoms of life. From bacteria to animals, metals have critical roles as both structural and catalytic cofactors for an estimated third of the proteome, representing a major contributor to the maintenance of cellular homeostasis. The reactivity of metal ions engenders them with the ability to promote enzyme catalysis and stabilize reaction intermediates. However, these properties render metals toxic at high concentrations and, therefore, metal levels must be tightly regulated. Having evolved in close association with bacteria, vertebrate hosts have developed numerous strategies of metal limitation and intoxication that prevent bacterial proliferation, a process termed nutritional immunity. In turn, bacterial pathogens have evolved adaptive mechanisms to survive in conditions of metal depletion or excess. In this Review, we discuss mechanisms by which nutrient metals shape the interactions between bacterial pathogens and animal hosts. We explore the cell-specific and tissue-specific roles of distinct trace metals in shaping bacterial infections, as well as implications for future research and new therapeutic development.
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Affiliation(s)
- Caitlin C Murdoch
- Department of Pathology, Microbiology and Immunology, Vanderbilt University School of Medicine, Nashville, TN, USA
- Vanderbilt Institute for Infection, Immunology and Inflammation, Vanderbilt University School of Medicine, Nashville, TN, USA
| | - Eric P Skaar
- Department of Pathology, Microbiology and Immunology, Vanderbilt University School of Medicine, Nashville, TN, USA.
- Vanderbilt Institute for Infection, Immunology and Inflammation, Vanderbilt University School of Medicine, Nashville, TN, USA.
- Vanderbilt Institute for Chemical Biology, Vanderbilt University, Nashville, TN, USA.
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10
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Mohammad M, Ali A, Nguyen MT, Götz F, Pullerits R, Jin T. Staphylococcus aureus lipoproteins in infectious diseases. Front Microbiol 2022; 13:1006765. [PMID: 36262324 PMCID: PMC9574248 DOI: 10.3389/fmicb.2022.1006765] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2022] [Accepted: 09/06/2022] [Indexed: 11/13/2022] Open
Abstract
Infections with the Gram-positive bacterial pathogen Staphylococcus aureus remain a major challenge for the healthcare system and demand new treatment options. The increasing antibiotic resistance of S. aureus poses additional challenges, consequently inflicting a huge strain in the society due to enormous healthcare costs. S. aureus expresses multiple molecules, including bacterial lipoproteins (Lpps), which play a role not only in immune response but also in disease pathogenesis. S. aureus Lpps, the predominant ligands of TLR2, are important for bacterial survival as they maintain the metabolic activity of the bacteria. Moreover, Lpps possess many diverse properties that are of vital importance for the bacteria. They also contribute to host cell invasion but so far their role in different staphylococcal infections has not been fully defined. In this review, we summarize the current knowledge about S. aureus Lpps and their distinct roles in various infectious disease animal models, such as septic arthritis, sepsis, and skin and soft tissue infections. The molecular and cellular response of the host to S. aureus Lpp exposure is also a primary focus.
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Affiliation(s)
- Majd Mohammad
- Department of Rheumatology and Inflammation Research, Institute of Medicine, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden
- *Correspondence: Majd Mohammad,
| | - Abukar Ali
- Department of Rheumatology and Inflammation Research, Institute of Medicine, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden
| | - Minh-Thu Nguyen
- Section of Medical and Geographical Infectiology, Institute of Medical Microbiology, University Hospital of Münster, Münster, Germany
| | - Friedrich Götz
- Department of Microbial Genetics, Interfaculty Institute of Microbiology and Infection Medicine Tübingen (IMIT), University of Tübingen, Tübingen, Germany
| | - Rille Pullerits
- Department of Rheumatology and Inflammation Research, Institute of Medicine, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden
- Department of Clinical Immunology and Transfusion Medicine, Sahlgrenska University Hospital, Gothenburg, Sweden
| | - Tao Jin
- Department of Rheumatology and Inflammation Research, Institute of Medicine, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden
- Department of Rheumatology, Sahlgrenska University Hospital, Gothenburg, Sweden
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11
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Clayton J, Ellis-Guardiola K, Mahoney BJ, Soule J, Clubb RT, Wereszczynski J. Directed inter-domain motions enable the IsdH Staphylococcus aureus receptor to rapidly extract heme from human hemoglobin. J Mol Biol 2022; 434:167623. [DOI: 10.1016/j.jmb.2022.167623] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2022] [Revised: 04/07/2022] [Accepted: 05/01/2022] [Indexed: 11/29/2022]
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12
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In vivo growth of Staphylococcus lugdunensis is facilitated by the concerted function of heme and non-heme iron acquisition mechanisms. J Biol Chem 2022; 298:101823. [PMID: 35283192 PMCID: PMC9052147 DOI: 10.1016/j.jbc.2022.101823] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2022] [Revised: 03/04/2022] [Accepted: 03/07/2022] [Indexed: 12/23/2022] Open
Abstract
Staphylococcus lugdunensis has increasingly been recognized as a pathogen that can cause serious infection indicating this bacterium overcomes host nutritional immunity. Despite this, there exists a significant knowledge gap regarding the iron acquisition mechanisms employed by S. lugdunensis, especially during infection of the mammalian host. Here we show that S. lugdunensis can usurp hydroxamate siderophores and staphyloferrin A and B from Staphylococcus aureus. These transport activities all required a functional FhuC ATPase. Moreover, we show that the acquisition of catechol siderophores and catecholamine stress hormones by S. lugdunensis required the presence of the sst-1 transporter-encoding locus, but not the sst-2 locus. Iron-dependent growth in acidic culture conditions necessitated the ferrous iron transport system encoded by feoAB. Heme iron was acquired via expression of the iron-regulated surface determinant (isd) locus. During systemic infection of mice, we demonstrated that while S. lugdunensis does not cause overt illness, it does colonize and proliferate to high numbers in the kidneys. By combining mutations in the various iron acquisition loci (isd, fhuC, sst-1, and feo), we demonstrate that only a strain deficient for all of these systems was attenuated in its ability to proliferate to high numbers in the murine kidney. We propose the concerted action of heme and non-heme iron acquisition systems also enable S. lugdunensis to cause human infection.
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Identification and Tetramer Structure of Hemin-Binding Protein SPD_0310 Linked to Iron Homeostasis and Virulence of Streptococcus pneumoniae. mSystems 2022; 7:e0022122. [PMID: 35414267 PMCID: PMC9238395 DOI: 10.1128/msystems.00221-22] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Iron and iron-containing compounds are essential for bacterial virulence and host infection. Hemin is an important supplement compound for bacterial survival in an iron-deficient environment. Despite strong interest in hemin metabolism, the detailed mechanism of hemin transportation in Gram-positive bacteria is yet to be reported. The results of our study revealed that the homologous proteins of SPD_0310 were significantly conservative in Gram-positive bacteria (P < 0.001), and these proteins were identified as belonging to an uncharacterized protein family (UPF0371). The results of thermodynamic and kinetic studies have shown that SPD_0310 has a high hemin-binding affinity. Interestingly, we found that the crystal structure of SPD_0310 presented a homotetramer conformation, which is required for hemin binding. SPD_0310 can interact with many hemin-binding proteins (SPD_0090, SPD_1609, and GAPDH) located on the cell surface, which contributes to hemin transfer to the cytoplasm. It also has a high affinity with other iron transporters in the cytoplasm (SPD_0226 and SPD_0227), which facilitates iron redistribution in cells. More importantly, the knockout of the spd_0310 gene (Δspd_0310) resulted in a decrease in the iron content and protein expression levels of many bacterial adhesion factors. Moreover, the animal model showed that the Δspd_0310 strain has a lower virulence than the wild type. Based on the crystallographic and biochemical studies, we inferred that SPD_0310 is a hemin intermediate transporter which contributes to iron homeostasis and further affects the virulence of Streptococcus pneumoniae in the host. Our study provides not only an important theoretical basis for the in-depth elucidation of the hemin transport mechanism in bacteria but also an important candidate target for the development of novel antimicrobial agents based on metal transport systems. IMPORTANCE Iron is an essential element for bacterial virulence and infection of the host. The detailed hemin metabolism in Gram-positive bacteria has rarely been studied. SPD_0310 belongs to the UPF0371 family of proteins, and results of homology analysis and evolutionary tree analysis suggested that it was widely distributed and highly conserved in Gram-positive bacteria. However, the function of the UPF0371 family remains unknown. We successfully determined the crystal structure of apo-SPD_0310, which is a homotetramer. We found that cytoplasmic protein SPD_0310 with a special tetramer structure has a strong hemin-binding ability and interacts with many iron transporters, which facilitates hemin transfer from the extracellular space to the cytoplasm. The results of detailed functional analyses indicated that SPD_0310 may function as a hemin transporter similar to hemoglobin in animals and contributes to bacterial iron homeostasis and virulence. This study provides a novel target for the development of antimicrobial drugs against pathogenic Gram-positive bacteria.
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De Bei O, Marchetti M, Ronda L, Gianquinto E, Lazzarato L, Chirgadze DY, Hardwick SW, Cooper LR, Spyrakis F, Luisi BF, Campanini B, Bettati S. Cryo-EM structures of staphylococcal IsdB bound to human hemoglobin reveal the process of heme extraction. Proc Natl Acad Sci U S A 2022; 119:e2116708119. [PMID: 35357971 PMCID: PMC9168843 DOI: 10.1073/pnas.2116708119] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2021] [Accepted: 02/11/2022] [Indexed: 12/02/2022] Open
Abstract
Iron surface determinant B (IsdB) is a hemoglobin (Hb) receptor essential for hemic iron acquisition by Staphylococcus aureus. Heme transfer to IsdB is possible from oxidized Hb (metHb), but inefficient from Hb either bound to oxygen (oxyHb) or bound to carbon monoxide (HbCO), and encompasses a sequence of structural events that are currently poorly understood. By single-particle cryo-electron microscopy, we determined the structure of two IsdB:Hb complexes, representing key species along the heme extraction pathway. The IsdB:HbCO structure, at 2.9-Å resolution, provides a snapshot of the preextraction complex. In this early stage of IsdB:Hb interaction, the hemophore binds to the β-subunits of the Hb tetramer, exploiting a folding-upon-binding mechanism that is likely triggered by a cis/trans isomerization of Pro173. Binding of IsdB to α-subunits occurs upon dissociation of the Hb tetramer into α/β dimers. The structure of the IsdB:metHb complex reveals the final step of the extraction process, where heme transfer to IsdB is completed. The stability of the complex, both before and after heme transfer from Hb to IsdB, is influenced by isomerization of Pro173. These results greatly enhance current understanding of structural and dynamic aspects of the heme extraction mechanism by IsdB and provide insight into the interactions that stabilize the complex before the heme transfer event. This information will support future efforts to identify inhibitors of heme acquisition by S. aureus by interfering with IsdB:Hb complex formation.
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Affiliation(s)
- Omar De Bei
- Interdepartmental Center Biopharmanet-TEC, University of Parma, Parma 43124, Italy
| | - Marialaura Marchetti
- Interdepartmental Center Biopharmanet-TEC, University of Parma, Parma 43124, Italy
- Department of Medicine and Surgery, University of Parma, Parma 43126, Italy
| | - Luca Ronda
- Interdepartmental Center Biopharmanet-TEC, University of Parma, Parma 43124, Italy
- Department of Medicine and Surgery, University of Parma, Parma 43126, Italy
- Institute of Biophysics, National Research Council, Pisa 56124, Italy
| | - Eleonora Gianquinto
- Department of Drug Science and Technology, University of Turin, Turin 10125, Italy
| | - Loretta Lazzarato
- Department of Drug Science and Technology, University of Turin, Turin 10125, Italy
| | - Dimitri Y. Chirgadze
- Department of Biochemistry, University of Cambridge, Cambridge CB2 1GA, United Kingdom
| | - Steven W. Hardwick
- Department of Biochemistry, University of Cambridge, Cambridge CB2 1GA, United Kingdom
| | - Lee R. Cooper
- Department of Biochemistry, University of Cambridge, Cambridge CB2 1GA, United Kingdom
| | - Francesca Spyrakis
- Department of Drug Science and Technology, University of Turin, Turin 10125, Italy
| | - Ben F. Luisi
- Department of Biochemistry, University of Cambridge, Cambridge CB2 1GA, United Kingdom
| | - Barbara Campanini
- Interdepartmental Center Biopharmanet-TEC, University of Parma, Parma 43124, Italy
- Department of Food and Drug, University of Parma, Parma 43124, Italy
| | - Stefano Bettati
- Interdepartmental Center Biopharmanet-TEC, University of Parma, Parma 43124, Italy
- Department of Medicine and Surgery, University of Parma, Parma 43126, Italy
- Institute of Biophysics, National Research Council, Pisa 56124, Italy
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15
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Xi Y, Wang H, Wang S, Wu X, Wang Z. A study of various factors affecting satellitism tests of Haemophilus influenzae and Haemophilus parainfluenzae using Staphylococcus aureus as the source of NAD. METHODS IN MICROBIOLOGY 2022; 193:106417. [PMID: 35033634 DOI: 10.1016/j.mimet.2022.106417] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/02/2021] [Revised: 01/09/2022] [Accepted: 01/10/2022] [Indexed: 10/19/2022]
Abstract
Many factors affecting satellitism tests are unclear, and it is difficult to avoid misidentification, even if the medium is properly selected. We investigated the factors causing false-positive results for Haemophilus influenzae and false-negative results for Haemophilus parainfluenzae in the satellitism tests using Staphylococcus aureus as the source of nicotinamide adenine dinucleotide (NAD). H. influenzae (four reference strains and 47 clinical isolates), H. parainfluenzae (two reference strains and 67 clinical isolates), four different media, and two strains of S. aureus revived on two different media were used in this study. The type of medium used to revive S. aureus was the most common factor causing false-positive results for H. influenzae, followed by different strains of S. aureus and the type of medium used for the experiment. The production of false-negative results for H. parainfluenzae was only related to the medium used in the experiment. To improve the accuracy of the tests in routine laboratories, using S. aureus as the source of NAD, tryptic soy agar, and S. aureus (ATCC 25923) revived on nutrient agar should be adopted.
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Affiliation(s)
- Yu Xi
- School of Life Sciences, Zhengzhou University, Zhengzhou, Henan, China
| | - Hexuan Wang
- Zhengzhou No. 47 Middle & High School, Zhengzhou, Henan, China
| | - Shanmei Wang
- Department of Clinical Laboratory, Henan Provincial People's Hospital, Zhengzhou, Henan, China
| | - Xuxiao Wu
- R&D Center, Autobio Diagnostics Co., Ltd, Zhengzhou, Henan, China
| | - Zeyu Wang
- R&D Center, Autobio Diagnostics Co., Ltd, Zhengzhou, Henan, China.
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16
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Heme-Dependent Siderophore Utilization Promotes Iron-Restricted Growth of the Staphylococcus aureus hemB Small-Colony Variant. J Bacteriol 2021; 203:e0045821. [PMID: 34606375 DOI: 10.1128/jb.00458-21] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
Respiration-deficient Staphylococcus aureus small-colony variants (SCVs) frequently cause persistent infections, which necessitates they acquire iron, yet how SCVs obtain iron remains unknown. To address this, we created a stable hemB mutant from S. aureus USA300 strain LAC. The hemB SCV utilized exogenously supplied hemin but was attenuated for growth under conditions of iron starvation. Transcriptome sequencing (RNA-seq) showed that both wild-type (WT) S. aureus and the hemB mutant sense and respond to iron starvation; however, growth assays show that the hemB mutant is defective for siderophore-mediated iron acquisition. Indeed, the hemB SCV demonstrated limited utilization of endogenous staphyloferrin B or exogenously provided staphyloferrin A, deferoxamine mesylate (Desferal), and epinephrine. Direct measurement of intracellular ATP in hemB and WT S. aureus revealed that both strains can generate comparable levels of ATP during exponential growth, suggesting defects in ATP production cannot account for the inability to efficiently utilize siderophores. Defective siderophore utilization by hemB bacteria was also evident in vivo, as administration of Desferal failed to promote hemB bacterial growth in every organ analyzed except for the kidneys. In support of the hypothesis that S. aureus accesses heme in kidney abscesses, in vitro analyses revealed that increased hemin availability enables hemB bacteria to utilize siderophores for growth when iron availability is restricted. Taken together, our data support the conclusion that hemin is used not only as an iron source itself but also as a nutrient that promotes utilization of siderophore-iron complexes. IMPORTANCE S. aureus small-colony variants (SCVs) are associated with chronic recurrent infection and worsened clinical outcome. SCVs persist within the host despite administration of antibiotics. This study yields insight into how S. aureus SCVs acquire iron, which during infection of a host is a difficult-to-acquire metal nutrient. Under hemin-limited conditions, hemB S. aureus is impaired for siderophore-dependent growth, and in agreement, murine infection indicates that hemin-deficient SCVs meet their nutritional requirement for iron through utilization of hemin. Importantly, we demonstrate that hemB SCVs rely upon hemin as a nutrient to promote siderophore utilization. Therefore, perturbation of heme biosynthesis and/or utilization represents a viable to strategy to mitigate the ability of SCV bacteria to acquire siderophore-bound iron during infection.
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Vahdani Y, Faraji N, Haghighat S, Yazdi MH, Mahdavi M. Molecular cloning and immunogenicity evaluation of IsdE protein of methicillin resistant Staphylococcus aureus as vaccine candidates. Microb Pathog 2021; 157:104953. [PMID: 34044042 DOI: 10.1016/j.micpath.2021.104953] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2020] [Revised: 04/17/2021] [Accepted: 04/19/2021] [Indexed: 10/21/2022]
Abstract
Methicillin resistant Staphylococcus aureus is one of the most common causes of nosocomial infections. Current therapeutic approaches are not always effective in treatment of nosocomial infections, thus, there is a global demand for the development of novel therapeutic strategies. Staphylococcus aureus possesses various systems to uptake iron. One of the most important of them is iron regulated surface determinant (Isd) which can be an excellent candidate for immunization. Here, following the preparation of recombinant IsdE protein, 20 μg of r-IsdE prepared in various formulations were subcutaneously injected in different groups of mice. Two booster vaccinations were administered in two-week intervals, then, blood samples were collected two weeks after each injection. ELISA was used for the evaluation of total IgG and its isotypes (IgG1 and IgG2a) as well as quantity of IFN-γ, IL-4, IL-17, IL-2 and TNF-α cytokines on the serum samples. Meanwhile, the immunized mice were intraperitoneally inoculated with 5 × 108 CFU of bacteria then, their mortality rate and bacterial load were assessed. Our results showed that immunization with the r-IsdE in various formulations raised total IgG and isotypes (IgG1 and IgG2a) compared with the control groups. Moreover, r-IsdE formulation with MF59 and Freund adjuvants raised production of IFN-γ, IL-4, IL-17, IL-2 and TNF-α cytokines and provided an acceptable protection against Staphylococcus aureus infections. Results of present study suggest that r-IsdE which can easily be expressed by Escherichia coli BL21 system shows a great potential to develop a protective immunity against infections caused by Methicillin resistant Staphylococcus aureus.
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Affiliation(s)
- Yasaman Vahdani
- Department of Microbiology, Faculty of Pharmaceutical Sciences, Tehran Medical Sciences, Islamic Azad University, Tehran, Iran
| | - Negin Faraji
- Department of Biotechnology, Faculty of Advanced Science and Technology, Tehran Medical Sciences, Islamic Azad University, Tehran, Iran
| | - Setareh Haghighat
- Department of Microbiology, Faculty of Advanced Science and Technology, Tehran Medical Sciences, Islamic Azad University, Tehran, Iran.
| | - Mohammad Hossein Yazdi
- Biotechnology Research Center, Faculty of Pharmacy, Tehran University of Medical Sciences, Tehran, Iran; Immunotherapy Group, The Institute of Pharmaceutical Sciences (TIPS), Tehran University of Medical Sciences, Tehran, Iran; Recombinant Vaccine Research Center, Tehran University of Medical Sciences, Tehran, Iran.
| | - Mehdi Mahdavi
- Immunotherapy Group, The Institute of Pharmaceutical Sciences (TIPS), Tehran University of Medical Sciences, Tehran, Iran; Recombinant Vaccine Research Center, Tehran University of Medical Sciences, Tehran, Iran
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Ellis-Guardiola K, Mahoney BJ, Clubb RT. NEAr Transporter (NEAT) Domains: Unique Surface Displayed Heme Chaperones That Enable Gram-Positive Bacteria to Capture Heme-Iron From Hemoglobin. Front Microbiol 2021; 11:607679. [PMID: 33488548 PMCID: PMC7815599 DOI: 10.3389/fmicb.2020.607679] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2020] [Accepted: 12/03/2020] [Indexed: 11/13/2022] Open
Abstract
Iron is an important micronutrient that is required by bacteria to proliferate and to cause disease. Many bacterial pathogens forage iron from human hemoglobin (Hb) during infections, which contains this metal within heme (iron-protoporphyrin IX). Several clinically important pathogenic species within the Firmicutes phylum scavenge heme using surface-displayed or secreted NEAr Transporter (NEAT) domains. In this review, we discuss how these versatile proteins function in the Staphylococcus aureus Iron-regulated surface determinant system that scavenges heme-iron from Hb. S. aureus NEAT domains function as either Hb receptors or as heme-binding chaperones. In vitro studies have shown that heme-binding NEAT domains can rapidly exchange heme amongst one another via transiently forming transfer complexes, leading to the interesting hypothesis that they may form a protein-wire within the peptidoglycan layer through which heme flows from the microbial surface to the membrane. In Hb receptors, recent studies have revealed how dedicated heme- and Hb-binding NEAT domains function synergistically to extract Hb's heme molecules, and how receptor binding to the Hb-haptoglobin complex may block its clearance by macrophages, prolonging microbial access to Hb's iron. The functions of NEAT domains in other Gram-positive bacteria are also reviewed.
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Affiliation(s)
- Ken Ellis-Guardiola
- Department of Chemistry and Biochemistry, University of California, Los Angeles, Los Angeles, CA, United States
- UCLA-DOE Institute for Genomics and Proteomics, University of California, Los Angeles, Los Angeles, CA, United States
| | - Brendan J. Mahoney
- Department of Chemistry and Biochemistry, University of California, Los Angeles, Los Angeles, CA, United States
- UCLA-DOE Institute for Genomics and Proteomics, University of California, Los Angeles, Los Angeles, CA, United States
| | - Robert T. Clubb
- Department of Chemistry and Biochemistry, University of California, Los Angeles, Los Angeles, CA, United States
- UCLA-DOE Institute for Genomics and Proteomics, University of California, Los Angeles, Los Angeles, CA, United States
- Molecular Biology Institute, University of California, Los Angeles, Los Angeles, CA, United States
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Scott C, Arora G, Dickson K, Lehmann C. Iron Chelation in Local Infection. Molecules 2021; 26:molecules26010189. [PMID: 33401708 PMCID: PMC7794793 DOI: 10.3390/molecules26010189] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2020] [Revised: 12/28/2020] [Accepted: 12/29/2020] [Indexed: 12/16/2022] Open
Abstract
Iron is an essential element in multiple biochemical pathways in humans and pathogens. As part of the innate immune response in local infection, iron availability is restricted locally in order to reduce overproduction of reactive oxygen species by the host and to attenuate bacterial growth. This physiological regulation represents the rationale for the therapeutic use of iron chelators to support induced iron deprivation and to treat infections. In this review paper we discuss the importance of iron regulation through examples of local infection and the potential of iron chelation in treating infection.
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Affiliation(s)
- Cassidy Scott
- Department of Anesthesia Pain Management and Perioperative Medicine, Dalhousie University, Halifax, NS B3H4H7, Canada; (G.A.); (K.D.); (C.L.)
- Department of Pharmacology, Dalhousie University, Halifax, NS B3H4H7, Canada
- Correspondence: ; Tel.: +1-(902)-494-1287
| | - Gaurav Arora
- Department of Anesthesia Pain Management and Perioperative Medicine, Dalhousie University, Halifax, NS B3H4H7, Canada; (G.A.); (K.D.); (C.L.)
- Department of Medicine, Dalhousie University, Halifax, NS B3H4R2, Canada
| | - Kayle Dickson
- Department of Anesthesia Pain Management and Perioperative Medicine, Dalhousie University, Halifax, NS B3H4H7, Canada; (G.A.); (K.D.); (C.L.)
- Department of Microbiology and Immunology, Dalhousie University, Halifax, NS B3H4H7, Canada
| | - Christian Lehmann
- Department of Anesthesia Pain Management and Perioperative Medicine, Dalhousie University, Halifax, NS B3H4H7, Canada; (G.A.); (K.D.); (C.L.)
- Department of Pharmacology, Dalhousie University, Halifax, NS B3H4H7, Canada
- Department of Medicine, Dalhousie University, Halifax, NS B3H4R2, Canada
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20
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Dauros-Singorenko P, Wiles S, Swift S. Staphylococcus aureus Biofilms and Their Response to a Relevant in vivo Iron Source. Front Microbiol 2020; 11:509525. [PMID: 33408695 PMCID: PMC7779473 DOI: 10.3389/fmicb.2020.509525] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2019] [Accepted: 11/23/2020] [Indexed: 11/29/2022] Open
Abstract
Biofilm infections can be chronic, life threatening and challenging to eradicate. Understanding in vivo stimuli affecting the biofilm cycle is one step toward targeted prevention strategies. Iron restriction by the host is a stimulus for biofilm formation for some Staphylococcus aureus isolates; however, in some infection scenarios bacteria are exposed to abundant amounts of hemoglobin (Hb), which S. aureus is able to use as iron source. Thus, we hypothesized a role for Hb in the biofilm infection. Microplate “biofilm” assays showed biofilm-matrix production was increased in the presence of hemoglobin when compared to the provision of iron as an inorganic salt. Microscopic analysis of biofilms showed that the provision of iron as hemoglobin consistently caused thicker and more structured biofilms when compared to the effect of the inorganic iron source. Iron responsive biofilm gene expression analysis showed that Agr Quorum Sensing, a known biofilm dispersal marker, was repressed with hemoglobin but induced with an equivalent amount of inorganic iron in the laboratory strain Newman. The gene expression of two biofilm structuring agents, PSMα and PSMβ, differed in the response to the iron source provided and was not correlated to hemoglobin-structured biofilms. A comparison of the model pathogen S. aureus Newman with local clinical isolates demonstrated that while there was a similar phenotypic biofilm response to hemoglobin, there was substantial variation in the expression of key biofilm dispersal markers, suggesting an underappreciated variation in biofilm regulome among S. aureus isolates and that no general inferences can be made by studying the behavior of single strains.
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Affiliation(s)
- Priscila Dauros-Singorenko
- Department of Molecular Medicine and Pathology, Faculty of Medical and Health Sciences, University of Auckland, Auckland, New Zealand
| | - Siouxsie Wiles
- Department of Molecular Medicine and Pathology, Faculty of Medical and Health Sciences, University of Auckland, Auckland, New Zealand
| | - Simon Swift
- Department of Molecular Medicine and Pathology, Faculty of Medical and Health Sciences, University of Auckland, Auckland, New Zealand
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21
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Nairz M, Weiss G. Iron in infection and immunity. Mol Aspects Med 2020; 75:100864. [PMID: 32461004 DOI: 10.1016/j.mam.2020.100864] [Citation(s) in RCA: 150] [Impact Index Per Article: 37.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2020] [Revised: 04/25/2020] [Accepted: 05/05/2020] [Indexed: 12/12/2022]
Abstract
Iron is an essential micronutrient for virtually all living cells. In infectious diseases, both invading pathogens and mammalian cells including those of the immune system require iron to sustain their function, metabolism and proliferation. On the one hand, microbial iron uptake is linked to the virulence of most human pathogens. On the other hand, the sequestration of iron from bacteria and other microorganisms is an efficient strategy of host defense in line with the principles of 'nutritional immunity'. In an acute infection, host-driven iron withdrawal inhibits the growth of pathogens. Chronic immune activation due to persistent infection, autoimmune disease or malignancy however, sequesters iron not only from infectious agents, autoreactive lymphocytes and neoplastic cells but also from erythroid progenitors. This is one of the key mechanisms which collectively result in the anemia of chronic inflammation. In this review, we highlight the most important interconnections between iron metabolism and immunity, focusing on host defense against relevant infections and on the clinical consequences of anemia of inflammation.
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Affiliation(s)
- Manfred Nairz
- Department of Internal Medicine II, Infectious Diseases, Immunology, Rheumatology, Pneumology, Medical University of Innsbruck, Austria
| | - Günter Weiss
- Department of Internal Medicine II, Infectious Diseases, Immunology, Rheumatology, Pneumology, Medical University of Innsbruck, Austria; Christian Doppler Laboratory for Iron Metabolism and Anemia Research, Medical University of Innsbruck, Austria.
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22
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Jochim A, Adolf L, Belikova D, Schilling NA, Setyawati I, Chin D, Meyers S, Verhamme P, Heinrichs DE, Slotboom DJ, Heilbronner S. An ECF-type transporter scavenges heme to overcome iron-limitation in Staphylococcus lugdunensis. eLife 2020; 9:e57322. [PMID: 32515736 PMCID: PMC7299338 DOI: 10.7554/elife.57322] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2020] [Accepted: 06/09/2020] [Indexed: 01/03/2023] Open
Abstract
Energy-coupling factor type transporters (ECF) represent trace nutrient acquisition systems. Substrate binding components of ECF-transporters are membrane proteins with extraordinary affinity, allowing them to scavenge trace amounts of ligand. A number of molecules have been described as substrates of ECF-transporters, but an involvement in iron-acquisition is unknown. Host-induced iron limitation during infection represents an effective mechanism to limit bacterial proliferation. We identified the iron-regulated ECF-transporter Lha in the opportunistic bacterial pathogen Staphylococcus lugdunensis and show that the transporter is specific for heme. The recombinant substrate-specific subunit LhaS accepted heme from diverse host-derived hemoproteins. Using isogenic mutants and recombinant expression of Lha, we demonstrate that its function is independent of the canonical heme acquisition system Isd and allows proliferation on human cells as sources of nutrient iron. Our findings reveal a unique strategy of nutritional heme acquisition and provide the first example of an ECF-transporter involved in overcoming host-induced nutritional limitation.
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Affiliation(s)
- Angelika Jochim
- Interfaculty Institute of Microbiology and Infection Medicine, Department of Infection Biology, University of TübingenTübingenGermany
| | - Lea Adolf
- Interfaculty Institute of Microbiology and Infection Medicine, Department of Infection Biology, University of TübingenTübingenGermany
| | - Darya Belikova
- Interfaculty Institute of Microbiology and Infection Medicine, Department of Infection Biology, University of TübingenTübingenGermany
| | | | - Inda Setyawati
- Groningen Biomolecular Sciences and Biotechnology Institute, University of GroningenGroningenNetherlands
| | - Denny Chin
- Department of Microbiology and Immunology, University of Western OntarioLondonCanada
| | | | | | - David E Heinrichs
- Department of Microbiology and Immunology, University of Western OntarioLondonCanada
| | - Dirk J Slotboom
- Groningen Biomolecular Sciences and Biotechnology Institute, University of GroningenGroningenNetherlands
| | - Simon Heilbronner
- Interfaculty Institute of Microbiology and Infection Medicine, Department of Infection Biology, University of TübingenTübingenGermany
- German Centre for Infection Research (DZIF), Partner Site TübingenTübingenGermany
- (DFG) Cluster of Excellence EXC 2124 Controlling Microbes to Fight InfectionsTübingenGermany
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23
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Marchetti M, De Bei O, Bettati S, Campanini B, Kovachka S, Gianquinto E, Spyrakis F, Ronda L. Iron Metabolism at the Interface between Host and Pathogen: From Nutritional Immunity to Antibacterial Development. Int J Mol Sci 2020; 21:E2145. [PMID: 32245010 PMCID: PMC7139808 DOI: 10.3390/ijms21062145] [Citation(s) in RCA: 42] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2020] [Revised: 03/16/2020] [Accepted: 03/17/2020] [Indexed: 02/08/2023] Open
Abstract
Nutritional immunity is a form of innate immunity widespread in both vertebrates and invertebrates. The term refers to a rich repertoire of mechanisms set up by the host to inhibit bacterial proliferation by sequestering trace minerals (mainly iron, but also zinc and manganese). This strategy, selected by evolution, represents an effective front-line defense against pathogens and has thus inspired the exploitation of iron restriction in the development of innovative antimicrobials or enhancers of antimicrobial therapy. This review focuses on the mechanisms of nutritional immunity, the strategies adopted by opportunistic human pathogen Staphylococcus aureus to circumvent it, and the impact of deletion mutants on the fitness, infectivity, and persistence inside the host. This information finally converges in an overview of the current development of inhibitors targeting the different stages of iron uptake, an as-yet unexploited target in the field of antistaphylococcal drug discovery.
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Affiliation(s)
- Marialaura Marchetti
- Interdepartmental Center Biopharmanet-TEC, University of Parma, 43124 Parma, Italy; (M.M.); (S.B.)
| | - Omar De Bei
- Department of Food and Drug, University of Parma, 43124 Parma, Italy; (O.D.B.); (B.C.)
| | - Stefano Bettati
- Interdepartmental Center Biopharmanet-TEC, University of Parma, 43124 Parma, Italy; (M.M.); (S.B.)
- Department of Medicine and Surgery, University of Parma, 43126 Parma, Italy
- Institute of Biophysics, National Research Council, 56124 Pisa, Italy
- National Institute of Biostructures and Biosystems, 00136 Rome, Italy
| | - Barbara Campanini
- Department of Food and Drug, University of Parma, 43124 Parma, Italy; (O.D.B.); (B.C.)
| | - Sandra Kovachka
- Department of Drug Science and Technology, University of Turin, 10125 Turin, Italy; (S.K.); (E.G.); (F.S.)
| | - Eleonora Gianquinto
- Department of Drug Science and Technology, University of Turin, 10125 Turin, Italy; (S.K.); (E.G.); (F.S.)
| | - Francesca Spyrakis
- Department of Drug Science and Technology, University of Turin, 10125 Turin, Italy; (S.K.); (E.G.); (F.S.)
| | - Luca Ronda
- Interdepartmental Center Biopharmanet-TEC, University of Parma, 43124 Parma, Italy; (M.M.); (S.B.)
- Department of Medicine and Surgery, University of Parma, 43126 Parma, Italy
- Institute of Biophysics, National Research Council, 56124 Pisa, Italy
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24
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Bennett MR, Bombardi RG, Kose N, Parrish EH, Nagel MB, Petit RA, Read TD, Schey KL, Thomsen IP, Skaar EP, Crowe JE. Human mAbs to Staphylococcus aureus IsdA Provide Protection Through Both Heme-Blocking and Fc-Mediated Mechanisms. J Infect Dis 2020; 219:1264-1273. [PMID: 30496483 DOI: 10.1093/infdis/jiy635] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2018] [Accepted: 11/17/2018] [Indexed: 11/13/2022] Open
Abstract
The nutrient metal iron plays a key role in the survival of microorganisms. The iron-regulated surface determinant (Isd) system scavenges heme-iron from the human host, enabling acquisition of iron in iron-deplete conditions in Staphylococcus aureus during infection. The cell surface receptors IsdB and IsdH bind hemoproteins and transfer heme to IsdA, the final surface protein before heme-iron is transported through the peptidoglycan. To define the human B-cell response to IsdA, we isolated human monoclonal antibodies (mAbs) specific to the surface Isd proteins and determined their mechanism of action. We describe the first isolation of fully human IsdA and IsdH mAbs, as well as cross-reactive Isd mAbs. Two of the identified IsdA mAbs worked in a murine septic model of infection to reduce bacterial burden during staphylococcal infection. Their protection was a result of both heme-blocking and Fc-mediated effector functions, underscoring the importance of targeting S. aureus using diverse mechanisms.
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Affiliation(s)
- Monique R Bennett
- Department of Pathology, Microbiology and Immunology, Nashville, Tennessee
| | - Robin G Bombardi
- Vanderbilt Vaccine Center, Vanderbilt University Medical Center, Nashville, Tennessee
| | - Nurgun Kose
- Vanderbilt Vaccine Center, Vanderbilt University Medical Center, Nashville, Tennessee
| | - Erica H Parrish
- Vanderbilt Vaccine Center, Vanderbilt University Medical Center, Nashville, Tennessee
| | - Marcus B Nagel
- Department of Biochemistry, Vanderbilt University, Nashville, Tennessee
| | - Robert A Petit
- Department of Medicine, Division of Infectious Diseases, Emory University School of Medicine, Atlanta, Georgia
| | - Timothy D Read
- Department of Medicine, Division of Infectious Diseases, Emory University School of Medicine, Atlanta, Georgia
| | - Kevin L Schey
- Department of Biochemistry, Vanderbilt University, Nashville, Tennessee
| | - Isaac P Thomsen
- Department of Pediatrics, Vanderbilt University Medical Center, Nashville, Tennessee
| | - Eric P Skaar
- Department of Pathology, Microbiology and Immunology, Nashville, Tennessee.,Vanderbilt Institute for Infection, Immunology and Inflammation, Vanderbilt University Medical Center, Nashville, Tennessee
| | - James E Crowe
- Department of Pathology, Microbiology and Immunology, Nashville, Tennessee.,Vanderbilt Vaccine Center, Vanderbilt University Medical Center, Nashville, Tennessee.,Department of Pediatrics, Vanderbilt University Medical Center, Nashville, Tennessee.,Vanderbilt Institute for Infection, Immunology and Inflammation, Vanderbilt University Medical Center, Nashville, Tennessee
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25
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The Staphylococcus aureus IsdH Receptor Forms a Dynamic Complex with Human Hemoglobin that Triggers Heme Release via Two Distinct Hot Spots. J Mol Biol 2019; 432:1064-1082. [PMID: 31881209 DOI: 10.1016/j.jmb.2019.12.023] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2019] [Revised: 11/22/2019] [Accepted: 12/12/2019] [Indexed: 02/02/2023]
Abstract
Iron is an essential nutrient that is actively acquired by bacterial pathogens during infections. Clinically important Staphylococcus aureus obtains iron by extracting heme from hemoglobin (Hb) using the closely related IsdB and IsdH surface receptors. In IsdH, extraction is mediated by a conserved tridomain unit that contains its second (N2) and third (N3) NEAT domains joined by a helical linker, called IsdHN2N3. Leveraging the crystal structure of the IsdHN2N3:Hb complex, we have probed the mechanism of heme capture using NMR, stopped-flow transfer kinetics measurements, and molecular dynamics (MD) simulations. NMR studies of the 220 kDa IsdHN2N3:Hb complex reveal that it is dynamic, with persistent interdomain motions enabling the linker and N3 domains in the receptor to transiently engage Hb to remove its heme. An alanine mutagenesis analysis reveals that two receptor subsites positioned ~20 Å apart trigger heme release by contacting Hb's F-helix. These subsites are located within the N3 and linker domains and appear to play distinct roles in stabilizing the heme transfer transition state. Linker domain contacts primarily function to destabilize Hb-heme interactions, thereby lowering ΔH‡, while contacts from the N3 subsite play a similar destabilizing role, but also form a bridge through which heme moves from Hb to the receptor. Interestingly, MD simulations suggest that within the transiently forming interface, both the F-helix and receptor bridge are in motion, dynamically sampling conformations that are suitable for heme transfer. Thus, IsdH triggers heme release from Hb via a flexible, low-affinity interface that forms fleetingly in solution.
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26
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Gianquinto E, Moscetti I, De Bei O, Campanini B, Marchetti M, Luque FJ, Cannistraro S, Ronda L, Bizzarri AR, Spyrakis F, Bettati S. Interaction of human hemoglobin and semi-hemoglobins with the Staphylococcus aureus hemophore IsdB: a kinetic and mechanistic insight. Sci Rep 2019; 9:18629. [PMID: 31819099 PMCID: PMC6901573 DOI: 10.1038/s41598-019-54970-w] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2019] [Accepted: 11/21/2019] [Indexed: 12/21/2022] Open
Abstract
Among multidrug-resistant bacteria, methicillin-resistant Staphylococcus aureus is emerging as one of the most threatening pathogens. S. aureus exploits different mechanisms for its iron supply, but the preferred one is acquisition of organic iron through the expression of hemoglobin (Hb) receptors. One of these, IsdB, belonging to the Isd (Iron-Regulated Surface Determinant) system, was shown to be essential for bacterial growth and virulence. Therefore, interaction of IsdB with Hb represents a promising target for the rational design of a new class of antibacterial molecules. However, despite recent investigations, many structural and mechanistic details of complex formation and heme extraction process are still elusive. By combining site-directed mutagenesis, absorption spectroscopy, surface plasmon resonance and molecular dynamics simulations, we tackled most of the so far unanswered questions: (i) the exact complex stoichiometry, (ii) the microscopic kinetic rates of complex formation, (iii) the IsdB selectivity for binding to, and extracting heme from, α and β subunits of Hb, iv) the role of specific amino acid residues and structural regions in driving complex formation and heme transfer, and (v) the structural/dynamic effect played by the hemophore on Hb.
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Affiliation(s)
- Eleonora Gianquinto
- Department of Drug Science and Technology, University of Turin, Turin, 10125, Italy
| | - Ilaria Moscetti
- Department of Environmental and Biological Sciences, University of Tuscia, Viterbo, 01100, Italy
| | - Omar De Bei
- Department of Food and Drug, University of Parma, Parma, 43124, Italy
| | - Barbara Campanini
- Department of Food and Drug, University of Parma, Parma, 43124, Italy.,Interdepartment Center Biopharmanet-TEC, University of Parma, Parma, 43124, Italy
| | - Marialaura Marchetti
- Department of Drug Science and Technology, University of Turin, Turin, 10125, Italy.,Interdepartment Center Biopharmanet-TEC, University of Parma, Parma, 43124, Italy
| | - F Javier Luque
- Department of Nutrition, Food Science and Gastronomy, Faculty of Pharmacy and Food Sciences, Institute of Biomedicine (IBUB) and Institute of Theoretical and Computational Chemistry (IQTCUB), University of Barcelona, Santa Coloma de Gramenet, 08921, Spain
| | - Salvatore Cannistraro
- Department of Environmental and Biological Sciences, University of Tuscia, Viterbo, 01100, Italy
| | - Luca Ronda
- Interdepartment Center Biopharmanet-TEC, University of Parma, Parma, 43124, Italy.,Department of Medicine and Surgery, University of Parma, Parma, 43126, Italy.,Institute of Biophysics, National Research Council, Pisa, 56124, Italy
| | - Anna Rita Bizzarri
- Department of Environmental and Biological Sciences, University of Tuscia, Viterbo, 01100, Italy.
| | - Francesca Spyrakis
- Department of Drug Science and Technology, University of Turin, Turin, 10125, Italy.
| | - Stefano Bettati
- Interdepartment Center Biopharmanet-TEC, University of Parma, Parma, 43124, Italy. .,Department of Medicine and Surgery, University of Parma, Parma, 43126, Italy. .,Institute of Biophysics, National Research Council, Pisa, 56124, Italy.
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27
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Bennett MR, Dong J, Bombardi RG, Soto C, Parrington HM, Nargi RS, Schoeder CT, Nagel MB, Schey KL, Meiler J, Skaar EP, Crowe JE. Human VH1-69 Gene-Encoded Human Monoclonal Antibodies against Staphylococcus aureus IsdB Use at Least Three Distinct Modes of Binding To Inhibit Bacterial Growth and Pathogenesis. mBio 2019; 10:e02473-19. [PMID: 31641091 PMCID: PMC6805997 DOI: 10.1128/mbio.02473-19] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2019] [Accepted: 09/18/2019] [Indexed: 12/30/2022] Open
Abstract
Staphylococcus aureus is an important human pathogen that infects nearly every human tissue. Like most organisms, the acquisition of nutrient iron is necessary for its survival. One route by which it obtains this metal is through the iron-regulated surface determinant (Isd) system that scavenges iron from the hemoglobin of the host. We show that the heavy chain variable region IGHV1-69 gene commonly encodes human monoclonal antibodies (mAbs) targeting IsdB-NEAT2. Remarkably, these antibodies bind to multiple antigenic sites. One class of IGHV1-69-encoded mAbs blocks S. aureus heme acquisition by binding to the heme-binding site of NEAT2, while two additional classes reduce the bacterial burden in vivo by an alternative Fc receptor-mediated mechanism. We further identified clonal lineages of IGHV1-69-encoded mAbs using donor samples, showing that each lineage diversifies during infection by somatic hypermutation. These studies reveal that IGHV1-69-encoded antibodies contribute to a protective immune response, furthering our understanding of the correlates of protection against S. aureus infection.IMPORTANCE The human pathogen Staphylococcus aureus causes a wide range of infections, including skin abscesses and sepsis. There is currently no licensed vaccine to prevent S. aureus infection, and its treatment has become increasingly difficult due to antibiotic resistance. One potential way to inhibit S. aureus pathogenesis is to prevent iron acquisition. The iron-regulated surface determinant (Isd) system has evolved in S. aureus to acquire hemoglobin from the human host as a source of heme-iron. In this study, we investigated the molecular and structural basis for antibody-mediated correlates against a member of the Isd system, IsdB. The association of immunoglobulin heavy chain variable region IGHV1-69 gene-encoded human monoclonal antibodies with the response against S. aureus IsdB is described using structural and functional studies to define the importance of this antibody class. We also determine that somatic hypermutation in the development of these antibodies hinders rather than fine-tunes the immune response to IsdB.
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Affiliation(s)
- Monique R Bennett
- Department of Pathology, Microbiology and Immunology, Vanderbilt University Medical Center, Nashville, Tennessee, USA
| | - Jinhui Dong
- Vanderbilt Vaccine Center, Vanderbilt University Medical Center, Nashville, Tennessee, USA
| | - Robin G Bombardi
- Vanderbilt Vaccine Center, Vanderbilt University Medical Center, Nashville, Tennessee, USA
| | - Cinque Soto
- Vanderbilt Vaccine Center, Vanderbilt University Medical Center, Nashville, Tennessee, USA
| | - Helen M Parrington
- Department of Pathology, Microbiology and Immunology, Vanderbilt University Medical Center, Nashville, Tennessee, USA
| | - Rachel S Nargi
- Vanderbilt Vaccine Center, Vanderbilt University Medical Center, Nashville, Tennessee, USA
| | - Clara T Schoeder
- Department of Chemistry, Vanderbilt University, Nashville, Tennessee, USA
| | - Marcus B Nagel
- Department of Biochemistry, Vanderbilt University, Nashville, Tennessee, USA
| | - Kevin L Schey
- Department of Biochemistry, Vanderbilt University, Nashville, Tennessee, USA
| | - Jens Meiler
- Department of Biochemistry, Vanderbilt University, Nashville, Tennessee, USA
| | - Eric P Skaar
- Department of Pathology, Microbiology and Immunology, Vanderbilt University Medical Center, Nashville, Tennessee, USA
- Vanderbilt Institute for Infection, Immunology and Inflammation, Vanderbilt University Medical Center, Nashville, Tennessee, USA
| | - James E Crowe
- Department of Pathology, Microbiology and Immunology, Vanderbilt University Medical Center, Nashville, Tennessee, USA
- Vanderbilt Vaccine Center, Vanderbilt University Medical Center, Nashville, Tennessee, USA
- Department of Pediatrics, Vanderbilt University School of Medicine, Nashville, Tennessee, USA
- Vanderbilt Institute for Infection, Immunology and Inflammation, Vanderbilt University Medical Center, Nashville, Tennessee, USA
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28
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Yang XY, Li N, Xu JY, Sun X, He QY. Lipoprotein SPD_1609 of Streptococcus pneumoniae Promotes Adherence and Invasion to Epithelial Cells Contributing to Bacterial Virulence. Front Microbiol 2019; 10:1769. [PMID: 31417540 PMCID: PMC6682666 DOI: 10.3389/fmicb.2019.01769] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2019] [Accepted: 07/17/2019] [Indexed: 01/06/2023] Open
Abstract
In most bacteria, iron plays a vital role in pathogenesis processes. To support survival and infection, Streptococcus pneumoniae has evolved three ABC transporters, PiaABC, PiuABC, and PitABC. Moreover, indirect evidence supports that operon 804 may be a novel ABC transporter in S. pneumoniae. We have recently described the identification of lipoprotein SPD_1609 in operon 804; however, whether the SPD_1609 protein affects the virulence of S. pneumoniae has not yet been studied. In the present work, alignment analysis showed that lipoprotein SPD_1609 is conserved in a variety of gram-positive bacteria, and deletion of the spd_1609 gene led to a reduction in adherence and invasion of S. pneumoniae to host cells. RT-qPCR assays indicated that deletion of the spd_1609 gene resulted in decreased expression of genes involved in colonization. Furthermore, decreased virulence in a mouse bacteremia infection model caused by the loss of the lipoprotein encoded by spd_1609 was also demonstrated. Overall, these data provide insights into the functional role of lipoprotein SPD_1609 in pneumococcal pathogenesis, suggesting its possibility to be developed as a novel S. pneumoniae vaccine candidate.
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Affiliation(s)
- Xiao-Yan Yang
- Zhuhai Key Laboratory of Basic and Applied Research in Chinese Medicine, Department of Bioengineering, Zhuhai Campus of Zunyi Medical University, Zhuhai, China.,Key Laboratory of Functional Protein Research of Guangdong Higher Education Institutes, Institute of Life and Health Engineering, College of Life Science and Technology, Jinan University, Guangzhou, China
| | - Nan Li
- Key Laboratory of Functional Protein Research of Guangdong Higher Education Institutes, Institute of Life and Health Engineering, College of Life Science and Technology, Jinan University, Guangzhou, China
| | - Jing-Yu Xu
- Key Laboratory of Functional Protein Research of Guangdong Higher Education Institutes, Institute of Life and Health Engineering, College of Life Science and Technology, Jinan University, Guangzhou, China
| | - Xuesong Sun
- Key Laboratory of Functional Protein Research of Guangdong Higher Education Institutes, Institute of Life and Health Engineering, College of Life Science and Technology, Jinan University, Guangzhou, China
| | - Qing-Yu He
- Key Laboratory of Functional Protein Research of Guangdong Higher Education Institutes, Institute of Life and Health Engineering, College of Life Science and Technology, Jinan University, Guangzhou, China
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29
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Macdonald R, Mahoney BJ, Ellis-Guardiola K, Maresso A, Clubb RT. NMR experiments redefine the hemoglobin binding properties of bacterial NEAr-iron Transporter domains. Protein Sci 2019; 28:1513-1523. [PMID: 31120610 DOI: 10.1002/pro.3662] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2019] [Accepted: 05/14/2019] [Indexed: 01/02/2023]
Abstract
Iron is a versatile metal cofactor that is used in a wide range of essential cellular processes. During infections, many bacterial pathogens acquire iron from human hemoglobin (Hb), which contains the majority of the body's total iron content in the form of heme (iron protoporphyrin IX). Clinically important Gram-positive bacterial pathogens scavenge heme using an array of secreted and cell-wall-associated receptors that contain NEAr-iron Transporter (NEAT) domains. Experimentally defining the Hb binding properties of NEAT domains has been challenging, limiting our understanding of their function in heme uptake. Here we show that solution-state NMR spectroscopy is a powerful tool to define the Hb binding properties of NEAT domains. The utility of this method is demonstrated using the NEAT domains from Bacillus anthracis and Listeria monocytogenes. Our results are compatible with the existence of at least two types of NEAT domains that are capable of interacting with either Hb or heme. These binding properties can be predicted from their primary sequences, with Hb- and heme-binding NEAT domains being distinguished by the presence of (F/Y)YH(Y/F) and S/YXXXY motifs, respectively. The results of this work should enable the functions of a wide range of NEAT domain containing proteins in pathogenic bacteria to be reliably predicted.
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Affiliation(s)
- Ramsay Macdonald
- Department of Chemistry and Biochemistry, University of California, Los Angeles, Los Angeles, California, 90095.,UCLA-DOE Institute of Genomics and Proteomics, University of California, Los Angeles, Los Angeles, California, 90095
| | - Brendan J Mahoney
- Department of Chemistry and Biochemistry, University of California, Los Angeles, Los Angeles, California, 90095.,UCLA-DOE Institute of Genomics and Proteomics, University of California, Los Angeles, Los Angeles, California, 90095
| | - Ken Ellis-Guardiola
- Department of Chemistry and Biochemistry, University of California, Los Angeles, Los Angeles, California, 90095.,UCLA-DOE Institute of Genomics and Proteomics, University of California, Los Angeles, Los Angeles, California, 90095
| | - Anthony Maresso
- Department of Molecular Virology and Microbiology, Baylor College of Medicine, Houston, Texas, 77030
| | - Robert T Clubb
- Department of Chemistry and Biochemistry, University of California, Los Angeles, Los Angeles, California, 90095.,UCLA-DOE Institute of Genomics and Proteomics, University of California, Los Angeles, Los Angeles, California, 90095.,Molecular Biology Institute, University of California, Los Angeles, Los Angeles, California, 90095
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30
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Conroy BS, Grigg JC, Kolesnikov M, Morales LD, Murphy MEP. Staphylococcus aureus heme and siderophore-iron acquisition pathways. Biometals 2019; 32:409-424. [PMID: 30911924 DOI: 10.1007/s10534-019-00188-2] [Citation(s) in RCA: 32] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2018] [Accepted: 03/18/2019] [Indexed: 11/24/2022]
Abstract
Staphylococcus aureus is a versatile opportunistic human pathogen. Infection by this bacterium requires uptake of iron from the human host, but iron is highly restricted in this environment. Staphylococcus aureus iron sufficiency is achieved primarily through uptake of heme and high-affinity iron chelators, known as siderophores. Two siderophores (staphyloferrins) are produced and secreted by S. aureus into the extracellular environment to capture iron. Staphylococcus aureus expresses specific uptake systems for staphyloferrins and more general uptake systems for siderophores produced by other microorganisms. The S. aureus heme uptake system uses highly-specific cell surface receptors to extract heme from hemoglobin and hemoglobin-haptoglobin complexes for transport into the cytoplasm where it is degraded to liberate iron. Initially thought to be independent systems, recent findings indicate that these iron uptake pathways intersect. IruO is a reductase that releases iron from heme and some ferric-siderophores. Moreover, multifunctional SbnI produces a precursor for staphyloferrin B biosynthesis, and also binds heme to regulate expression of the staphyloferrin B biosynthesis pathway. Intersection of the S. aureus iron uptake pathways is hypothesized to be important for rapid adaptation to available iron sources. Components of the heme and siderophore uptake systems are currently being targeted in the development of therapeutics against S. aureus.
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Affiliation(s)
- Brigid S Conroy
- Department of Microbiology and Immunology, Life Sciences Institute, The University of British Columbia, 2350 Health Sciences Mall, Vancouver, V6T 1Z3, Canada
| | - Jason C Grigg
- Department of Microbiology and Immunology, Life Sciences Institute, The University of British Columbia, 2350 Health Sciences Mall, Vancouver, V6T 1Z3, Canada
| | - Maxim Kolesnikov
- Department of Microbiology and Immunology, Life Sciences Institute, The University of British Columbia, 2350 Health Sciences Mall, Vancouver, V6T 1Z3, Canada
| | - L Daniela Morales
- Department of Microbiology and Immunology, Life Sciences Institute, The University of British Columbia, 2350 Health Sciences Mall, Vancouver, V6T 1Z3, Canada
| | - Michael E P Murphy
- Department of Microbiology and Immunology, Life Sciences Institute, The University of British Columbia, 2350 Health Sciences Mall, Vancouver, V6T 1Z3, Canada.
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31
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Schneewind O, Missiakas D. Sortases, Surface Proteins, and Their Roles in Staphylococcus aureus Disease and Vaccine Development. Microbiol Spectr 2019; 7:10.1128/microbiolspec.PSIB-0004-2018. [PMID: 30737913 PMCID: PMC6386163 DOI: 10.1128/microbiolspec.psib-0004-2018] [Citation(s) in RCA: 35] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2018] [Indexed: 12/27/2022] Open
Abstract
Sortases cleave short peptide motif sequences at the C-terminal end of secreted surface protein precursors and either attach these polypeptides to the peptidoglycan of Gram-positive bacteria or promote their assembly into pilus structures that are also attached to peptidoglycan. Sortase A, the enzyme first identified in the human pathogen Staphylococcus aureus, binds LPXTG motif sorting signals, cleaves between threonine (T) and glycine (G) residues, and forms an acyl enzyme between its active-site cysteine thiol and the carboxyl group of threonine (T). Sortase A acyl enzyme is relieved by the nucleophilic attack of the cross bridge amino group within lipid II, thereby generating surface protein linked to peptidoglycan precursor. Such products are subsequently incorporated into the cell wall envelope by enzymes of the peptidoglycan synthesis pathway. Surface proteins linked to peptidoglycan may be released from the bacterial envelope to diffuse into host tissues and fulfill specific biological functions. S. aureus sortase A is essential for host colonization and for the pathogenesis of invasive diseases. Staphylococcal sortase-anchored surface proteins fulfill key functions during the infectious process, and vaccine-induced antibodies targeting surface proteins may provide protection against S. aureus. Alternatively, small-molecule inhibitors of sortase may be useful agents for the prevention of S. aureus colonization and invasive disease.
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Affiliation(s)
- Olaf Schneewind
- Department of Microbiology, University of Chicago, Chicago, IL 60637
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32
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Macdonald R, Cascio D, Collazo MJ, Phillips M, Clubb RT. The Streptococcus pyogenes Shr protein captures human hemoglobin using two structurally unique binding domains. J Biol Chem 2018; 293:18365-18377. [PMID: 30301765 DOI: 10.1074/jbc.ra118.005261] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2018] [Revised: 10/03/2018] [Indexed: 12/19/2022] Open
Abstract
In order to proliferate and mount an infection, many bacterial pathogens need to acquire iron from their host. The most abundant iron source in the body is the oxygen transporter hemoglobin (Hb). Streptococcus pyogenes, a potentially lethal human pathogen, uses the Shr protein to capture Hb on the cell surface. Shr is an important virulence factor, yet the mechanism by which it captures Hb and acquires its heme is not well-understood. Here, we show using NMR and biochemical methods that Shr binds Hb using two related modules that were previously defined as domains of unknown function (DUF1533). These hemoglobin-interacting domains (HIDs), called HID1 and HID2, are autonomously folded and independently bind Hb. The 1.5 Å resolution crystal structure of HID2 revealed that it is a structurally unique Hb-binding domain. Mutagenesis studies revealed a conserved tyrosine in both HIDs that is essential for Hb binding. Our biochemical studies indicate that HID2 binds Hb with higher affinity than HID1 and that the Hb tetramer is engaged by two Shr receptors. NMR studies reveal the presence of a third autonomously folded domain between HID2 and a heme-binding NEAT1 domain, suggesting that this linker domain may position NEAT1 near Hb for heme capture.
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Affiliation(s)
- Ramsay Macdonald
- From the Department of Chemistry and Biochemistry,; UCLA-DOE Institute of Genomics and Proteomics and
| | | | | | | | - Robert T Clubb
- From the Department of Chemistry and Biochemistry,; UCLA-DOE Institute of Genomics and Proteomics and; Molecular Biology Institute, UCLA, Los Angeles, California 90095.
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33
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Abstract
During infection, bacteria must steal metals, including iron, from the host tissue. Therefore, pathogenic bacteria have evolved metal acquisition systems to overcome the elaborate processes mammals use to withhold metal from pathogens. Staphylococcus aureus uses IsdB, a hemoglobin receptor, to thieve iron-containing heme from hemoglobin within human blood. We find evidence that primate hemoglobin has undergone rapid evolution at protein surfaces contacted by IsdB. Additionally, variation in the hemoglobin sequences among primates, or variation in IsdB of related staphylococci, reduces bacterial hemoglobin capture. Together, these data suggest that S. aureus has evolved to recognize human hemoglobin in the face of rapid evolution at the IsdB binding interface, consistent with repeated evolutionary conflicts in the battle for iron during host-pathogen interactions. Metals are a limiting resource for pathogenic bacteria and must be scavenged from host proteins. Hemoglobin provides the most abundant source of iron in the human body and is required by several pathogens to cause invasive disease. However, the consequences of hemoglobin evolution for bacterial nutrient acquisition remain unclear. Here we show that the α- and β-globin genes exhibit strikingly parallel signatures of adaptive evolution across simian primates. Rapidly evolving sites in hemoglobin correspond to binding interfaces of IsdB, a bacterial hemoglobin receptor harbored by pathogenic Staphylococcus aureus. Using an evolution-guided experimental approach, we demonstrate that the divergence between primates and staphylococcal isolates governs hemoglobin recognition and bacterial growth. The reintroduction of putative adaptive mutations in α- or β-globin proteins was sufficient to impair S. aureus binding, providing a mechanism for the evolution of disease resistance. These findings suggest that bacterial hemoprotein capture has driven repeated evolutionary conflicts with hemoglobin during primate descent.
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34
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Mozzi A, Forni D, Clerici M, Cagliani R, Sironi M. The Diversity of Mammalian Hemoproteins and Microbial Heme Scavengers Is Shaped by an Arms Race for Iron Piracy. Front Immunol 2018; 9:2086. [PMID: 30271410 PMCID: PMC6142043 DOI: 10.3389/fimmu.2018.02086] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2018] [Accepted: 08/23/2018] [Indexed: 11/13/2022] Open
Abstract
Iron is an essential micronutrient for most living species. In mammals, hemoglobin (Hb) stores more than two thirds of the body's iron content. In the bloodstream, haptoglobin (Hp) and hemopexin (Hpx) sequester free Hb or heme. Pathogenic microorganisms usually acquire iron from their hosts and have evolved complex systems of iron piracy to circumvent nutritional immunity. Herein, we performed an evolutionary analysis of genes coding for mammalian heme-binding proteins and heme-scavengers in pathogen species. The underlying hypothesis is that these molecules are engaged in a molecular arms race. We show that positive selection drove the evolution of mammalian Hb and Hpx. Positively selected sites in Hb are located at the interaction surface with Neisseria meningitidis heme scavenger HpuA and with Staphylococcus aureus iron-regulated surface determinant B (IsdB). In turn, positively selected sites in HpuA and IsdB are located in the flexible protein regions that contact Hb. A residue in Hb (S45H) was also selected on the Caprinae branch. This site stabilizes the interaction with Trypanosoma brucei hemoglobin-haptoglobin (HbHp) receptor (TbHpHbR), a molecule that also mediates trypanosome lytic factor (TLF) entry. In TbHpHbR, positive selection drove the evolution of a variant (L210S) which allows evasion from TLF but reduces affinity for HbHp. Finally, selected sites in Hpx are located at the interaction surface with the Haemophilus influenzae hemophore HxuA, which in turn displays fast evolving sites at the Hpx-binding interface. These results shed light into host-pathogens conflicts and establish the importance of nutritional immunity as an evolutionary force.
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Affiliation(s)
- Alessandra Mozzi
- Scientific Institute, IRCCS E. Medea, Bioinformatics, Lecco, Italy
| | - Diego Forni
- Scientific Institute, IRCCS E. Medea, Bioinformatics, Lecco, Italy
| | - Mario Clerici
- Department of Physiopathology and Transplantation, University of Milan, Milan, Italy.,Don C. Gnocchi Foundation ONLUS, IRCCS, Milan, Italy
| | - Rachele Cagliani
- Scientific Institute, IRCCS E. Medea, Bioinformatics, Lecco, Italy
| | - Manuela Sironi
- Scientific Institute, IRCCS E. Medea, Bioinformatics, Lecco, Italy
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Sjodt M, Macdonald R, Marshall JD, Clayton J, Olson JS, Phillips M, Gell DA, Wereszczynski J, Clubb RT. Energetics underlying hemin extraction from human hemoglobin by Staphylococcus aureus. J Biol Chem 2018. [PMID: 29540481 DOI: 10.1074/jbc.ra117.000803] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
Staphylococcus aureus is a leading cause of life-threatening infections in the United States. It actively acquires the essential nutrient iron from human hemoglobin (Hb) using the iron-regulated surface-determinant (Isd) system. This process is initiated when the closely related bacterial IsdB and IsdH receptors bind to Hb and extract its hemin through a conserved tri-domain unit that contains two NEAr iron Transporter (NEAT) domains that are connected by a helical linker domain. Previously, we demonstrated that the tri-domain unit within IsdH (IsdHN2N3) triggers hemin release by distorting Hb's F-helix. Here, we report that IsdHN2N3 promotes hemin release from both the α- and β-subunits. Using a receptor mutant that only binds to the α-subunit of Hb and a stopped-flow transfer assay, we determined the energetics and micro-rate constants of hemin extraction from tetrameric Hb. We found that at 37 °C, the receptor accelerates hemin release from Hb up to 13,400-fold, with an activation enthalpy of 19.5 ± 1.1 kcal/mol. We propose that hemin removal requires the rate-limiting hydrolytic cleavage of the axial HisF8 Nϵ-Fe3+ bond, which, based on molecular dynamics simulations, may be facilitated by receptor-induced bond hydration. Isothermal titration calorimetry experiments revealed that two distinct IsdHN2N3·Hb protein·protein interfaces promote hemin release. A high-affinity receptor·Hb(A-helix) interface contributed ∼95% of the total binding standard free energy, enabling much weaker receptor interactions with Hb's F-helix that distort its hemin pocket and cause unfavorable changes in the binding enthalpy. We present a model indicating that receptor-introduced structural distortions and increased solvation underlie the IsdH-mediated hemin extraction mechanism.
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Affiliation(s)
- Megan Sjodt
- From the Department of Chemistry and Biochemistry.,UCLA-DOE Institute of Genomics and Proteomics, and
| | - Ramsay Macdonald
- From the Department of Chemistry and Biochemistry.,UCLA-DOE Institute of Genomics and Proteomics, and
| | | | - Joseph Clayton
- the Department of Physics and Center for Molecular Study of Condensed Soft Matter, Illinois Institute of Technology, Chicago, Illinois 60616
| | - John S Olson
- the Department of BioSciences, Rice University, Houston, Texas 77251, and
| | | | - David A Gell
- the School of Medicine, University of Tasmania, Hobart, Tasmania 7000, Australia
| | - Jeff Wereszczynski
- the Department of Physics and Center for Molecular Study of Condensed Soft Matter, Illinois Institute of Technology, Chicago, Illinois 60616
| | - Robert T Clubb
- From the Department of Chemistry and Biochemistry, .,UCLA-DOE Institute of Genomics and Proteomics, and.,Molecular Biology Institute, UCLA, Los Angeles, California 90095
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36
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Corynebacterium diphtheriae Iron-Regulated Surface Protein HbpA Is Involved in the Utilization of the Hemoglobin-Haptoglobin Complex as an Iron Source. J Bacteriol 2018; 200:JB.00676-17. [PMID: 29311283 DOI: 10.1128/jb.00676-17] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2017] [Accepted: 12/28/2017] [Indexed: 11/20/2022] Open
Abstract
Corynebacterium diphtheriae utilizes various heme-containing proteins, including hemoglobin (Hb) and the hemoglobin-haptoglobin complex (Hb-Hp), as iron sources during growth in iron-depleted environments. The ability to utilize Hb-Hp as an iron source requires the surface-anchored proteins HtaA and either ChtA or ChtC. The ability to bind hemin, Hb, and Hb-Hp by each of these C. diphtheriae proteins requires the previously characterized conserved region (CR) domain. In this study, we identified an Hb-Hp binding protein, HbpA (38.5 kDa), which is involved in the acquisition of hemin iron from Hb-Hp. HbpA was initially identified from total cell lysates as an iron-regulated protein that binds to both Hb and Hb-Hp in situ HbpA does not contain a CR domain and has sequence similarity only to homologous proteins present in a limited number of C. diphtheriae strains. Transcription of hbpA is regulated in an iron-dependent manner that is mediated by DtxR, a global iron-dependent regulator. Deletion of hbpA from C. diphtheriae results in a reduced ability to utilize Hb-Hp as an iron source but has little or no effect on the ability to use Hb or hemin as an iron source. Cell fractionation studies showed that HbpA is both secreted into the culture supernatant and associated with the membrane, where its exposure on the bacterial surface allows HbpA to bind Hb and Hb-Hp. The identification and analysis of HbpA enhance our understanding of iron uptake in C. diphtheriae and indicate that the acquisition of hemin iron from Hb-Hp may involve a complex mechanism that requires multiple surface proteins.IMPORTANCE The ability to utilize host iron sources, such as heme and heme-containing proteins, is essential for many bacterial pathogens to cause disease. In this study, we have identified a novel factor (HbpA) that is crucial for the use of hemin iron from the hemoglobin-haptoglobin complex (Hb-Hp). Hb-Hp is considered one of the primary sources of iron for certain bacterial pathogens. HbpA has no similarity to the previously identified Hb-Hp binding proteins, HtaA and ChtA/C, and is found only in a limited group of C. diphtheriae strains. Understanding the function of HbpA may significantly increase our knowledge of how this important human pathogen can acquire host iron that allows it to survive and cause disease in the human respiratory tract.
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Thomsen IP, Liu GY. Targeting fundamental pathways to disrupt Staphylococcus aureus survival: clinical implications of recent discoveries. JCI Insight 2018. [PMID: 29515041 DOI: 10.1172/jci.insight.98216] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
The emergence of community-associated methicillin-resistant Staphylococcus aureus during the past decade along with an impending shortage of effective antistaphylococcal antibiotics have fueled impressive advances in our understanding of how S. aureus overcomes the host environment to establish infection. Backed by recent technologic advances, studies have uncovered elaborate metabolic, nutritional, and virulence strategies deployed by S. aureus to survive the restrictive and hostile environment imposed by the host, leading to a plethora of promising antimicrobial approaches that have potential to remedy the antibiotic resistance crisis. In this Review, we highlight some of the critical and recently elucidated bacterial strategies that are potentially amenable to intervention, discuss their relevance to human diseases, and address the translational challenges posed by current animal models.
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Affiliation(s)
- Isaac P Thomsen
- Department of Pediatrics, Division of Pediatric Infectious Diseases, and Vanderbilt Vaccine Research Program, Vanderbilt University Medical Center, Nashville, Tennessee, USA
| | - George Y Liu
- Division of Pediatric Infectious Diseases and Research Division of Immunology, Department of Biomedical Sciences, Cedars-Sinai Medical Center, Los Angeles, California, USA
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38
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Bowden CFM, Chan ACK, Li EJW, Arrieta AL, Eltis LD, Murphy MEP. Structure-function analyses reveal key features in Staphylococcus aureus IsdB-associated unfolding of the heme-binding pocket of human hemoglobin. J Biol Chem 2017; 293:177-190. [PMID: 29109153 DOI: 10.1074/jbc.m117.806562] [Citation(s) in RCA: 36] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2017] [Revised: 10/19/2017] [Indexed: 11/06/2022] Open
Abstract
IsdB is a receptor on the surface of the bacterial pathogen Staphylococcus aureus that extracts heme from hemoglobin (Hb) to enable growth on Hb as a sole iron source. IsdB is critically important both for in vitro growth on Hb and in infection models and is also highly up-regulated in blood, serum, and tissue infection models, indicating a key role of this receptor in bacterial virulence. However, structural information for IsdB is limited. We present here a crystal structure of a complex between human Hb and IsdB. In this complex, the α subunits of Hb are refolded with the heme displaced to the interface with IsdB. We also observe that atypical residues of Hb, His58 and His89 of αHb, coordinate to the heme iron, which is poised for transfer into the heme-binding pocket of IsdB. Moreover, the porphyrin ring interacts with IsdB residues Tyr440 and Tyr444 Previously, Tyr440 was observed to coordinate heme iron in an IsdB·heme complex structure. A Y440F/Y444F IsdB variant we produced was defective in heme transfer yet formed a stable complex with Hb (Kd = 6 ± 2 μm) in solution with spectroscopic features of the bis-His species observed in the crystal structure. Haptoglobin binds to a distinct site on Hb to inhibit heme transfer to IsdB and growth of S. aureus, and a ternary complex of IsdB·Hb·Hp was observed. We propose a model for IsdB heme transfer from Hb that involves unfolding of Hb and heme iron ligand exchange.
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Affiliation(s)
- Catherine F M Bowden
- Department of Microbiology and Immunology, Life Sciences Institute, University of British Columbia, Vancouver, British Columbia V6T 1Z3, Canada
| | - Anson C K Chan
- Department of Microbiology and Immunology, Life Sciences Institute, University of British Columbia, Vancouver, British Columbia V6T 1Z3, Canada
| | - Emily J W Li
- Department of Microbiology and Immunology, Life Sciences Institute, University of British Columbia, Vancouver, British Columbia V6T 1Z3, Canada
| | - Angelé L Arrieta
- Department of Microbiology and Immunology, Life Sciences Institute, University of British Columbia, Vancouver, British Columbia V6T 1Z3, Canada
| | - Lindsay D Eltis
- Department of Microbiology and Immunology, Life Sciences Institute, University of British Columbia, Vancouver, British Columbia V6T 1Z3, Canada
| | - Michael E P Murphy
- Department of Microbiology and Immunology, Life Sciences Institute, University of British Columbia, Vancouver, British Columbia V6T 1Z3, Canada.
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Abstract
Iron is an essential micronutrient for both microbes and humans alike. For well over half a century we have known that this element, in particular, plays a pivotal role in health and disease and, most especially, in shaping host-pathogen interactions. Intracellular iron concentrations serve as a critical signal in regulating the expression not only of high-affinity iron acquisition systems in bacteria, but also of toxins and other noted virulence factors produced by some major human pathogens. While we now are aware of many strategies that the host has devised to sequester iron from invading microbes, there are as many if not more sophisticated mechanisms by which successful pathogens overcome nutritional immunity imposed by the host. This review discusses some of the essential components of iron sequestration and scavenging mechanisms of the host, as well as representative Gram-negative and Gram-positive pathogens, and highlights recent advances in the field. Last, we address how the iron acquisition strategies of pathogenic bacteria may be exploited for the development of novel prophylactics or antimicrobials.
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40
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Uluisik RC, Akbas N, Lukat-Rodgers GS, Adrian SA, Allen CE, Schmitt MP, Rodgers KR, Dixon DW. Characterization of the second conserved domain in the heme uptake protein HtaA from Corynebacterium diphtheriae. J Inorg Biochem 2017; 167:124-133. [PMID: 27974280 PMCID: PMC5199035 DOI: 10.1016/j.jinorgbio.2016.11.027] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2016] [Revised: 10/19/2016] [Accepted: 11/22/2016] [Indexed: 11/20/2022]
Abstract
HtaA is a heme-binding protein that is part of the heme uptake system in Corynebacterium diphtheriae. HtaA contains two conserved regions (CR1 and CR2). It has been previously reported that both domains can bind heme; the CR2 domain binds hemoglobin more strongly than the CR1 domain. In this study, we report the biophysical characteristics of HtaA-CR2. UV-visible spectroscopy and resonance Raman experiments are consistent with this domain containing a single heme that is bound to the protein through an axial tyrosine ligand. Mutants of conserved tyrosine and histidine residues (Y361, H412, and Y490) have been studied. These mutants are isolated with very little heme (≤5%) in comparison to the wild-type protein (~20%). Reconstitution after removal of the heme with butanone gave an alternative form of the protein. The HtaA-CR2 fold is very stable; it was necessary to perform thermal denaturation experiments in the presence of guanidinium hydrochloride. HtaA-CR2 unfolds extremely slowly; even in 6.8M GdnHCl at 37°C, the half-life was 5h. In contrast, the apo forms of WT HtaA-CR2 and the aforementioned mutants unfolded at much lower concentrations of GdnHCl, indicating the role of heme in stabilizing the structure and implying that heme transfer is effected only to a partner protein in vivo.
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Affiliation(s)
- Rizvan C Uluisik
- Department of Chemistry, Georgia State University, Atlanta, GA 30302-3965, United States
| | - Neval Akbas
- Department of Chemistry, Georgia State University, Atlanta, GA 30302-3965, United States
| | - Gudrun S Lukat-Rodgers
- Department of Chemistry and Biochemistry, North Dakota State University, Fargo, ND 58108-6050, United States
| | - Seth A Adrian
- Department of Chemistry and Biochemistry, North Dakota State University, Fargo, ND 58108-6050, United States
| | - Courtni E Allen
- Laboratory of Respiratory and Special Pathogens, Division of Bacterial, Parasitic, and Allergenic Products, Center for Biologics Evaluation, and Research, Food and Drug Administration, Silver Spring, MD 20993, United States
| | - Michael P Schmitt
- Laboratory of Respiratory and Special Pathogens, Division of Bacterial, Parasitic, and Allergenic Products, Center for Biologics Evaluation, and Research, Food and Drug Administration, Silver Spring, MD 20993, United States
| | - Kenton R Rodgers
- Department of Chemistry and Biochemistry, North Dakota State University, Fargo, ND 58108-6050, United States.
| | - Dabney W Dixon
- Department of Chemistry, Georgia State University, Atlanta, GA 30302-3965, United States.
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41
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Germline-encoded neutralization of a Staphylococcus aureus virulence factor by the human antibody repertoire. Nat Commun 2016; 7:13376. [PMID: 27857134 PMCID: PMC5120205 DOI: 10.1038/ncomms13376] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2016] [Accepted: 09/28/2016] [Indexed: 11/08/2022] Open
Abstract
Staphylococcus aureus is both an important pathogen and a human commensal. To explore this ambivalent relationship between host and microbe, we analysed the memory humoral response against IsdB, a protein involved in iron acquisition, in four healthy donors. Here we show that in all donors a heavily biased use of two immunoglobulin heavy chain germlines generated high affinity (pM) antibodies that neutralize the two IsdB NEAT domains, IGHV4-39 for NEAT1 and IGHV1-69 for NEAT2. In contrast to the typical antibody/antigen interactions, the binding is primarily driven by the germline-encoded hydrophobic CDRH-2 motifs of IGHV1-69 and IGHV4-39, with a binding mechanism nearly identical for each antibody derived from different donors. Our results suggest that IGHV1-69 and IGHV4-39, while part of the adaptive immune system, may have evolved under selection pressure to encode a binding motif innately capable of recognizing and neutralizing a structurally conserved protein domain involved in pathogen iron acquisition.
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42
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Choo JM, Cheung JK, Wisniewski JA, Steer DL, Bulach DM, Hiscox TJ, Chakravorty A, Smith AI, Gell DA, Rood JI, Awad MM. The NEAT Domain-Containing Proteins of Clostridium perfringens Bind Heme. PLoS One 2016; 11:e0162981. [PMID: 27637108 PMCID: PMC5026354 DOI: 10.1371/journal.pone.0162981] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2015] [Accepted: 08/31/2016] [Indexed: 12/27/2022] Open
Abstract
The ability of a pathogenic bacterium to scavenge iron from its host is important for its growth and survival during an infection. Our studies on C. perfringens gas gangrene strain JIR325, a derivative of strain 13, showed that it is capable of utilizing both human hemoglobin and ferric chloride, but not human holo-transferrin, as an iron source for in vitro growth. Analysis of the C. perfringens strain 13 genome sequence identified a putative heme acquisition system encoded by an iron-regulated surface gene region that we have named the Cht (Clostridium perfringensheme transport) locus. This locus comprises eight genes that are co-transcribed and includes genes that encode NEAT domain-containing proteins (ChtD and ChtE) and a putative sortase (Srt). The ChtD, ChtE and Srt proteins were shown to be expressed in JIR325 cells grown under iron-limited conditions and were localized to the cell envelope. Moreover, the NEAT proteins, ChtD and ChtE, were found to bind heme. Both chtDE and srt mutants were constructed, but these mutants were not defective in hemoglobin or ferric chloride utilization. They were, however, attenuated for virulence when tested in a mouse myonecrosis model, although the virulence phenotype could not be restored via complementation and, as is common with such systems, secondary mutations were identified in these strains. In summary, this study provides evidence for the functional redundancies that occur in the heme transport pathways of this life threatening pathogen.
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Affiliation(s)
- Jocelyn M. Choo
- Infection and Immunity Program, Biomedicine Discovery Institute and Department of Microbiology, Monash University, Clayton, VIC 3800, Australia
| | - Jackie K. Cheung
- Infection and Immunity Program, Biomedicine Discovery Institute and Department of Microbiology, Monash University, Clayton, VIC 3800, Australia
| | - Jessica A. Wisniewski
- Infection and Immunity Program, Biomedicine Discovery Institute and Department of Microbiology, Monash University, Clayton, VIC 3800, Australia
| | - David L. Steer
- Department of Biochemistry and Molecular Biology, Monash University, Clayton, Victoria, Australia
| | - Dieter M. Bulach
- Victorian Bioinformatics Consortium, Monash University, Clayton, Victoria, Australia
| | - Thomas J. Hiscox
- Infection and Immunity Program, Biomedicine Discovery Institute and Department of Microbiology, Monash University, Clayton, VIC 3800, Australia
| | - Anjana Chakravorty
- Infection and Immunity Program, Biomedicine Discovery Institute and Department of Microbiology, Monash University, Clayton, VIC 3800, Australia
| | - A. Ian Smith
- Victorian Bioinformatics Consortium, Monash University, Clayton, Victoria, Australia
| | - David A. Gell
- School of Medicine, University of Tasmania, Hobart, Tasmania 7000, Australia
| | - Julian I. Rood
- Infection and Immunity Program, Biomedicine Discovery Institute and Department of Microbiology, Monash University, Clayton, VIC 3800, Australia
| | - Milena M. Awad
- Infection and Immunity Program, Biomedicine Discovery Institute and Department of Microbiology, Monash University, Clayton, VIC 3800, Australia
- * E-mail:
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43
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Choby JE, Skaar EP. Heme Synthesis and Acquisition in Bacterial Pathogens. J Mol Biol 2016; 428:3408-28. [PMID: 27019298 PMCID: PMC5125930 DOI: 10.1016/j.jmb.2016.03.018] [Citation(s) in RCA: 201] [Impact Index Per Article: 25.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2016] [Revised: 03/16/2016] [Accepted: 03/17/2016] [Indexed: 02/06/2023]
Abstract
Bacterial pathogens require the iron-containing cofactor heme to cause disease. Heme is essential to the function of hemoproteins, which are involved in energy generation by the electron transport chain, detoxification of host immune effectors, and other processes. During infection, bacterial pathogens must synthesize heme or acquire heme from the host; however, host heme is sequestered in high-affinity hemoproteins. Pathogens have evolved elaborate strategies to acquire heme from host sources, particularly hemoglobin, and both heme acquisition and synthesis are important for pathogenesis. Paradoxically, excess heme is toxic to bacteria and pathogens must rely on heme detoxification strategies. Heme is a key nutrient in the struggle for survival between host and pathogen, and its study has offered significant insight into the molecular mechanisms of bacterial pathogenesis.
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Affiliation(s)
- Jacob E Choby
- Department of Pathology, Microbiology, & Immunology, Vanderbilt University School of Medicine, Nashville, TN, USA
| | - Eric P Skaar
- Department of Pathology, Microbiology, & Immunology, Vanderbilt University School of Medicine, Nashville, TN, USA; Tennessee Valley Healthcare System, U.S. Department of Veterans Affairs, Nashville, TN, USA.
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44
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Abstract
Staphylococcus aureus, like other bacterial pathogens, scavenges host iron for growth through incompletely understood mechanisms. In this issue of Cell Host & Microbe, Spaan et al. (2015) demonstrate that two Staphylococcus aureus leukotoxins, HlgAB and LukED, target the Duffy antigen receptor for chemokines on erythrocytes, resulting in lysis and iron release.
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45
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Flannagan RS, Heit B, Heinrichs DE. Antimicrobial Mechanisms of Macrophages and the Immune Evasion Strategies of Staphylococcus aureus. Pathogens 2015; 4:826-68. [PMID: 26633519 PMCID: PMC4693167 DOI: 10.3390/pathogens4040826] [Citation(s) in RCA: 128] [Impact Index Per Article: 14.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2015] [Revised: 11/17/2015] [Accepted: 11/24/2015] [Indexed: 12/21/2022] Open
Abstract
Habitually professional phagocytes, including macrophages, eradicate microbial invaders from the human body without overt signs of infection. Despite this, there exist select bacteria that are professional pathogens, causing significant morbidity and mortality across the globe and Staphylococcus aureus is no exception. S. aureus is a highly successful pathogen that can infect virtually every tissue that comprises the human body causing a broad spectrum of diseases. The profound pathogenic capacity of S. aureus can be attributed, in part, to its ability to elaborate a profusion of bacterial effectors that circumvent host immunity. Macrophages are important professional phagocytes that contribute to both the innate and adaptive immune response, however from in vitro and in vivo studies, it is evident that they fail to eradicate S. aureus. This review provides an overview of the antimicrobial mechanisms employed by macrophages to combat bacteria and describes the immune evasion strategies and some representative effectors that enable S. aureus to evade macrophage-mediated killing.
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Affiliation(s)
- Ronald S Flannagan
- Department of Microbiology and Immunology, the University of Western Ontario, London, ON N6A 5C1, Canada.
| | - Bryan Heit
- Department of Microbiology and Immunology, the University of Western Ontario, London, ON N6A 5C1, Canada.
- Centre for Human Immunology, the University of Western Ontario, London, ON N6A 5C1, Canada.
| | - David E Heinrichs
- Department of Microbiology and Immunology, the University of Western Ontario, London, ON N6A 5C1, Canada.
- Centre for Human Immunology, the University of Western Ontario, London, ON N6A 5C1, Canada.
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46
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Neyrolles O, Wolschendorf F, Mitra A, Niederweis M. Mycobacteria, metals, and the macrophage. Immunol Rev 2015; 264:249-63. [PMID: 25703564 DOI: 10.1111/imr.12265] [Citation(s) in RCA: 143] [Impact Index Per Article: 15.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Mycobacterium tuberculosis is a facultative intracellular pathogen that thrives inside host macrophages. A key trait of M. tuberculosis is to exploit and manipulate metal cation trafficking inside infected macrophages to ensure survival and replication inside the phagosome. Here, we describe the recent fascinating discoveries that the mammalian immune system responds to infections with M. tuberculosis by overloading the phagosome with copper and zinc, two metals which are essential nutrients in small quantities but are toxic in excess. M. tuberculosis has developed multi-faceted resistance mechanisms to protect itself from metal toxicity including control of uptake, sequestration inside the cell, oxidation, and efflux. The host response to infections combines this metal poisoning strategy with nutritional immunity mechanisms that deprive M. tuberculosis from metals such as iron and manganese to prevent bacterial replication. Both immune mechanisms rely on the translocation of metal transporter proteins to the phagosomal membrane during the maturation process of the phagosome. This review summarizes these recent findings and discusses how metal-targeted approaches might complement existing TB chemotherapeutic regimens with novel anti-infective therapies.
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Affiliation(s)
- Olivier Neyrolles
- Institut de Pharmacologie et de Biologie Structurale, Centre National de la Recherche Scientifique, Toulouse, France; Institut de Pharmacologie et de Biologie Structurale, Univer-sité Paul Sabatier, Université de Toulouse, Toulouse, France
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47
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Laakso HA, Marolda CL, Pinter TB, Stillman MJ, Heinrichs DE. A Heme-responsive Regulator Controls Synthesis of Staphyloferrin B in Staphylococcus aureus. J Biol Chem 2015; 291:29-40. [PMID: 26534960 DOI: 10.1074/jbc.m115.696625] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2015] [Indexed: 11/06/2022] Open
Abstract
Staphylococcus aureus possesses a multitude of mechanisms by which it can obtain iron during growth under iron starvation conditions. It expresses an effective heme acquisition system (the iron-regulated surface determinant system), it produces two carboxylate-type siderophores staphyloferrin A and staphyloferrin B (SB), and it expresses transporters for many other siderophores that it does not synthesize. The ferric uptake regulator protein regulates expression of genes encoding all of these systems. Mechanisms of fine-tuning expression of iron-regulated genes, beyond simple iron regulation via ferric uptake regulator, have not been uncovered in this organism. Here, we identify the ninth gene of the sbn operon, sbnI, as encoding a ParB/Spo0J-like protein that is required for expression of genes in the sbn operon from sbnD onward. Expression of sbnD-I is drastically decreased in an sbnI mutant, and the mutant does not synthesize detectable SB during early phases of growth. Thus, SB-mediated iron acquisition is impaired in an sbnI mutant strain. We show that the protein forms dimers and tetramers in solution and binds to DNA within the sbnC coding region. Moreover, we show that SbnI binds heme and that heme-bound SbnI does not bind DNA. Finally, we show that providing exogenous heme to S. aureus growing in an iron-free medium results in delayed synthesis of SB. This is the first study in S. aureus that identifies a DNA-binding regulatory protein that senses heme to control gene expression for siderophore synthesis.
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Affiliation(s)
| | | | | | | | - David E Heinrichs
- From the Departments of Microbiology and Immunology and Centre for Human Immunology, University of Western Ontario, London, Ontario N6A 5C1, Canada
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48
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Soares MP, Weiss G. The Iron age of host-microbe interactions. EMBO Rep 2015; 16:1482-500. [PMID: 26474900 DOI: 10.15252/embr.201540558] [Citation(s) in RCA: 138] [Impact Index Per Article: 15.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2015] [Accepted: 09/23/2015] [Indexed: 12/25/2022] Open
Abstract
Microbes exert a major impact on human health and disease by either promoting or disrupting homeostasis, in the latter instance leading to the development of infectious diseases. Such disparate outcomes are driven by the ever-evolving genetic diversity of microbes and the countervailing host responses that minimize their pathogenic impact. Host defense strategies that limit microbial pathogenicity include resistance mechanisms that exert a negative impact on microbes, and disease tolerance mechanisms that sustain host homeostasis without interfering directly with microbes. While genetically distinct, these host defense strategies are functionally integrated, via mechanisms that remain incompletely defined. Here, we explore the general principles via which host adaptive responses regulating iron (Fe) metabolism impact on resistance and disease tolerance to infection.
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Affiliation(s)
| | - Günter Weiss
- Department of Internal Medicine VI, Infectious Diseases, Immunology, Rheumatology, Pneumology, Medical University, Innsbruck, Austria
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Yu S, Zhang H, Yao D, Liu W, Wang X, Chen X, Wei Y, Zhang Z, Wang J, Yu L, Sun H, Wu Z, Yu Y, Song B, Ma J, Tong C, Cui Y. Identification of CD4+ T-cell epitopes on iron-regulated surface determinant B of Staphylococcus aureus. Microb Pathog 2015; 89:108-13. [PMID: 26423555 DOI: 10.1016/j.micpath.2015.09.006] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2015] [Accepted: 09/10/2015] [Indexed: 11/30/2022]
Abstract
Iron-regulated surface determinant B (IsdB) of Staphylococcus aureus (S. aureus) is a highly conserved surface protein that can induce protective CD4(+) T-cell immune response. A pivotal role of CD4(+) T-cells in effective immunity against S. aureus infection has been proved, but CD4(+) T-cell epitopes on the S. aureus IsdB have not been well identified. In this study, MHC binding assay was firstly used to predict CD4(+) T-cell epitopes on S. aureus IsdB protein, and six peptides were synthesized to validate the probable epitopes. Two novel IsdB CD4(+) T-cell epitopes, P1 (residues 159-178) and P4 (residues 287-306), were for the first time identified using CD4(+) T-cells obtained from IsdB-immunized C57BL/6 (H-2(b)) and BALB/c (H-2(d)) mice spleen based on cell proliferation and cytokines response. The results showed that P1 and P4 emulsified in Freund's adjuvant (FA) induced much higher cell proliferation compared with PBS emulsified in FA. CD4(+) T-cells stimulated with peptides P1 and P4 secreted significantly higher levels of IFN-γ and IL-17A. However, the level of the cytokine IL-4 almost remained unchanged, suggesting that P1 and P4 preferentially elicited polarized Th1-type responses. In addition, BALB/c mice just respond to P4 not P1, while C57BL/6 mice respond to P1 not P4, implying that epitope P1 and P4 were determined as H-2(b) and H-2(d) restricted epitope, respectively. Taken together, our data may provide an explanation of the IsdB-induced protection against S. aureus and highlight the possibility of developing the epitope-based vaccine against the S. aureus.
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Affiliation(s)
- Simiao Yu
- College of Life Science and Technology, HeiLongJiang BaYi Agricultural University, Daqing 163319, China
| | - Hua Zhang
- College of Life Science and Technology, HeiLongJiang BaYi Agricultural University, Daqing 163319, China
| | - Di Yao
- College of Animal Science and Veterinary Medicine, HeiLongJiang BaYi Agricultural University, Daqing 163319, China
| | - Wei Liu
- College of Life Science and Technology, HeiLongJiang BaYi Agricultural University, Daqing 163319, China
| | - Xintong Wang
- College of Life Science and Technology, HeiLongJiang BaYi Agricultural University, Daqing 163319, China
| | - Xiaoting Chen
- College of Animal Science and Veterinary Medicine, HeiLongJiang BaYi Agricultural University, Daqing 163319, China
| | - Yuhua Wei
- College of Animal Science and Veterinary Medicine, HeiLongJiang BaYi Agricultural University, Daqing 163319, China
| | - Zhenghai Zhang
- College of Life Science and Technology, HeiLongJiang BaYi Agricultural University, Daqing 163319, China
| | - Jiannan Wang
- College of Life Science and Technology, HeiLongJiang BaYi Agricultural University, Daqing 163319, China
| | - Liquan Yu
- College of Life Science and Technology, HeiLongJiang BaYi Agricultural University, Daqing 163319, China
| | - Hunan Sun
- College of Life Science and Technology, HeiLongJiang BaYi Agricultural University, Daqing 163319, China
| | - Zhijun Wu
- College of Life Science and Technology, HeiLongJiang BaYi Agricultural University, Daqing 163319, China
| | - Yongzhong Yu
- College of Life Science and Technology, HeiLongJiang BaYi Agricultural University, Daqing 163319, China
| | - Baifen Song
- College of Life Science and Technology, HeiLongJiang BaYi Agricultural University, Daqing 163319, China
| | - Jinzhu Ma
- College of Life Science and Technology, HeiLongJiang BaYi Agricultural University, Daqing 163319, China
| | - Chunyu Tong
- College of Life Science and Technology, HeiLongJiang BaYi Agricultural University, Daqing 163319, China
| | - Yudong Cui
- College of Life Science and Technology, HeiLongJiang BaYi Agricultural University, Daqing 163319, China; College of Animal Science and Veterinary Medicine, HeiLongJiang BaYi Agricultural University, Daqing 163319, China.
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50
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Yoong P, Torres VJ. Counter inhibition between leukotoxins attenuates Staphylococcus aureus virulence. Nat Commun 2015; 6:8125. [PMID: 26330208 PMCID: PMC4562310 DOI: 10.1038/ncomms9125] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2014] [Accepted: 07/21/2015] [Indexed: 02/07/2023] Open
Abstract
Staphylococcus aureus subverts host defences by producing a collection of virulence factors including bi-component pore-forming leukotoxins. Despite extensive sequence conservation, each leukotoxin has unique properties, including disparate cellular receptors and species specificities. How these toxins collectively influence S. aureus pathogenesis is unknown. Here we demonstrate that the leukotoxins LukSF-PV and LukED antagonize each other's cytolytic activities on leukocytes and erythrocytes by forming inactive hybrid complexes. Remarkably, LukSF-PV inhibition of LukED haemolytic activity on both human and murine erythrocytes prevents the release of nutrients required for in vitro bacterial growth. Using in vivo murine models of infection, we show that LukSF-PV negatively influences S. aureus virulence and colonization by inhibiting LukED. Thus, while S. aureus leukotoxins can certainly injure immune cells, the discovery of leukotoxin antagonism suggests that they may also play a role in reducing S. aureus virulence and maintaining infection without killing the host. Staphylococcus aureus strains produce a family of highly related toxins that puncture the cytoplasmic membrane of susceptible cells. Here, Yoong and Torres show that the toxins can counteract each other in a cell type-dependent manner by forming inactive hybrid complexes, thus modulating S. aureus virulence.
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Affiliation(s)
- Pauline Yoong
- Department of Microbiology, New York University School of Medicine, New York, New York 10016, USA
| | - Victor J Torres
- Department of Microbiology, New York University School of Medicine, New York, New York 10016, USA
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