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Meireles D, Pombinho R, Cabanes D. Signals behind Listeria monocytogenes virulence mechanisms. Gut Microbes 2024; 16:2369564. [PMID: 38979800 PMCID: PMC11236296 DOI: 10.1080/19490976.2024.2369564] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/16/2024] [Accepted: 06/13/2024] [Indexed: 07/10/2024] Open
Abstract
The tight and coordinated regulation of virulence gene expression is crucial to ensure the survival and persistence of bacterial pathogens in different contexts within their hosts. Considering this, bacteria do not express virulence factors homogenously in time and space, either due to their associated fitness cost or to their detrimental effect at specific infection stages. To efficiently infect and persist into their hosts, bacteria have thus to monitor environmental cues or chemical cell-to-cell signaling mechanisms that allow their transition from the external environment to the host, and therefore adjust gene expression levels, intrinsic biological activities, and appropriate behaviors. Listeria monocytogenes (Lm), a major Gram-positive facultative intracellular pathogen, stands out for its adaptability and capacity to thrive in a wide range of environments. Because of that, Lm presents itself as a significant concern in food safety and public health, that can lead to potentially life-threatening infections in humans. A deeper understanding of the intricate bacterial virulence mechanisms and the signals that control them provide valuable insights into the dynamic interplay between Lm and the host. Therefore, this review addresses the role of some crucial signals behind Lm pathogenic virulence mechanisms and explores how the ability to assimilate and interpret these signals is fundamental for pathogenesis, identifying potential targets for innovative antimicrobial strategies.
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Affiliation(s)
- Diana Meireles
- Instituto de Investigação e Inovação em Saúde, Porto, Portugal
- Group of Molecular Microbiology, IBMC, Porto, Portugal
- Instituto de Ciências Biomédicas Abel Salazar – ICBAS, Porto, Portugal
| | - Rita Pombinho
- Instituto de Investigação e Inovação em Saúde, Porto, Portugal
- Group of Molecular Microbiology, IBMC, Porto, Portugal
| | - Didier Cabanes
- Instituto de Investigação e Inovação em Saúde, Porto, Portugal
- Group of Molecular Microbiology, IBMC, Porto, Portugal
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2
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Riffaud CM, Rucks EA, Ouellette SP. Persistence of obligate intracellular pathogens: alternative strategies to overcome host-specific stresses. Front Cell Infect Microbiol 2023; 13:1185571. [PMID: 37284502 PMCID: PMC10239878 DOI: 10.3389/fcimb.2023.1185571] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2023] [Accepted: 05/05/2023] [Indexed: 06/08/2023] Open
Abstract
In adapting to the intracellular niche, obligate intracellular bacteria usually undergo a reduction of genome size by eliminating genes not needed for intracellular survival. These losses can include, for example, genes involved in nutrient anabolic pathways or in stress response. Living inside a host cell offers a stable environment where intracellular bacteria can limit their exposure to extracellular effectors of the immune system and modulate or outright inhibit intracellular defense mechanisms. However, highlighting an area of vulnerability, these pathogens are dependent on the host cell for nutrients and are very sensitive to conditions that limit nutrient availability. Persistence is a common response shared by evolutionarily divergent bacteria to survive adverse conditions like nutrient deprivation. Development of persistence usually compromises successful antibiotic therapy of bacterial infections and is associated with chronic infections and long-term sequelae for the patients. During persistence, obligate intracellular pathogens are viable but not growing inside their host cell. They can survive for a long period of time such that, when the inducing stress is removed, reactivation of their growth cycles resumes. Given their reduced coding capacity, intracellular bacteria have adapted different response mechanisms. This review gives an overview of the strategies used by the obligate intracellular bacteria, where known, which, unlike model organisms such as E. coli, often lack toxin-antitoxin systems and the stringent response that have been linked to a persister phenotype and amino acid starvation states, respectively.
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3
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Cheung GYC, Bae JS, Otto M. Pathogenicity and virulence of Staphylococcus aureus. Virulence 2021; 12:547-569. [PMID: 33522395 PMCID: PMC7872022 DOI: 10.1080/21505594.2021.1878688] [Citation(s) in RCA: 457] [Impact Index Per Article: 152.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2020] [Revised: 01/13/2021] [Accepted: 01/15/2021] [Indexed: 12/15/2022] Open
Abstract
Staphylococcus aureus is one of the most frequent worldwide causes of morbidity and mortality due to an infectious agent. This pathogen can cause a wide variety of diseases, ranging from moderately severe skin infections to fatal pneumonia and sepsis. Treatment of S. aureus infections is complicated by antibiotic resistance and a working vaccine is not available. There has been ongoing and increasing interest in the extraordinarily high number of toxins and other virulence determinants that S. aureus produces and how they impact disease. In this review, we will give an overview of how S. aureus initiates and maintains infection and discuss the main determinants involved. A more in-depth understanding of the function and contribution of S. aureus virulence determinants to S. aureus infection will enable us to develop anti-virulence strategies to counteract the lack of an anti-S. aureus vaccine and the ever-increasing shortage of working antibiotics against this important pathogen.
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Affiliation(s)
- Gordon Y. C. Cheung
- Pathogen Molecular Genetics Section, Laboratory of Bacteriology, National Institute of Allergy and Infectious Diseases, U.S. National Institutes of Health, Bethesda, Maryland, USA
| | - Justin S. Bae
- Pathogen Molecular Genetics Section, Laboratory of Bacteriology, National Institute of Allergy and Infectious Diseases, U.S. National Institutes of Health, Bethesda, Maryland, USA
| | - Michael Otto
- Pathogen Molecular Genetics Section, Laboratory of Bacteriology, National Institute of Allergy and Infectious Diseases, U.S. National Institutes of Health, Bethesda, Maryland, USA
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4
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Tahmasebi H, Dehbashi S, Arabestani MR. Antibiotic resistance alters through iron-regulating Sigma factors during the interaction of Staphylococcus aureus and Pseudomonas aeruginosa. Sci Rep 2021; 11:18509. [PMID: 34531485 PMCID: PMC8445946 DOI: 10.1038/s41598-021-98017-5] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2021] [Accepted: 09/02/2021] [Indexed: 12/26/2022] Open
Abstract
Iron is a limiting factor in such a condition that usually is sequestered by the host during polymicrobial infections of Pseudomonas aeruginosa and Staphylococcus aureus. This study aimed to investigate the interaction of S. aureus and P. aeruginosa, which alters iron-related sigma factors regulation and antibiotic resistance. The antibiotic resistance of P. aeruginosa and S. aureus was investigated in a L929 cell culture model. The expression level of pvdS, hasI (P. aeruginosa sigma factors), and sigS (S. aureus sigma factor) genes was determined using Quantitative Real-Time PCR. pvdS and hasI were downregulated during co-culture with S. aureus, while the susceptibility to carbapenems increased (p-value < 0.0001). Also, there was a direct significant relationship between resistance to vancomycin with sigS. Regarding the findings of the current study, iron-related sigma factors of P. aeruginosa and S. aureus play a role in induction susceptibility to various antibiotics, including carbapenems and vancomycin.
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Affiliation(s)
- Hamed Tahmasebi
- School of Medicine, Shahroud University of Medical Sciences, Shahroud, Iran
| | - Sanaz Dehbashi
- Department of Microbiology, Faculty of Medicine, Hamadan University of Medical Sciences, Hamadan, Iran
| | - Mohammad Reza Arabestani
- Department of Microbiology, Faculty of Medicine, Hamadan University of Medical Sciences, Hamadan, Iran.
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5
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Dong Y, Miao X, Zheng YD, Liu J, He QY, Ge R, Sun X. Ciprofloxacin-Resistant Staphylococcus aureus Displays Enhanced Resistance and Virulence in Iron-Restricted Conditions. J Proteome Res 2021; 20:2839-2850. [PMID: 33872026 DOI: 10.1021/acs.jproteome.1c00077] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The unreasonable misuse of antibiotics has led to the emergence of large-scale drug-resistant bacteria, seriously threatening human health. Compared with drug-sensitive bacteria, resistant bacteria are difficult to clear by host immunity. To fully explore the adaptive mechanism of resistant bacteria to the iron-restricted environment, we performed data-independent acquisition-based quantitative proteomics on ciprofloxacin (CIP)-resistant (CIP-R) Staphylococcus aureus in the presence or absence of iron. On bioinformatics analysis, CIP-R bacteria showed stronger amino acid synthesis and energy storage ability. Notably, CIP-R bacteria increased virulence by upregulating the expression of many virulence-related proteins and enhancing the synthesis of virulence-related amino acids under iron-restricted stress. This study will help us to further explain the adaptive mechanisms that lead to bacterial resistance to antibiotics depending on the host environment and provide insights into the development of novel drugs for the treatment of drug-resistant bacterial infections.
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Affiliation(s)
- Yingshan Dong
- MOE Key Laboratory of Tumor Molecular Biology and Key Laboratory of Functional Protein Research of Guangdong Higher Education Institutes, Institute of Life and Health Engineering, Jinan University, Guangzhou 510632, China
| | - Xinyu Miao
- MOE Key Laboratory of Tumor Molecular Biology and Key Laboratory of Functional Protein Research of Guangdong Higher Education Institutes, Institute of Life and Health Engineering, Jinan University, Guangzhou 510632, China
| | - Yun-Dan Zheng
- MOE Key Laboratory of Tumor Molecular Biology and Key Laboratory of Functional Protein Research of Guangdong Higher Education Institutes, Institute of Life and Health Engineering, Jinan University, Guangzhou 510632, China
| | - Jiajia Liu
- MOE Key Laboratory of Tumor Molecular Biology and Key Laboratory of Functional Protein Research of Guangdong Higher Education Institutes, Institute of Life and Health Engineering, Jinan University, Guangzhou 510632, China
| | - Qing-Yu He
- MOE Key Laboratory of Tumor Molecular Biology and Key Laboratory of Functional Protein Research of Guangdong Higher Education Institutes, Institute of Life and Health Engineering, Jinan University, Guangzhou 510632, China
| | - Ruiguang Ge
- State Key Laboratory of Biocontrol, College of Life Sciences, Sun Yat-sen University, Guangzhou 510275, China
| | - Xuesong Sun
- MOE Key Laboratory of Tumor Molecular Biology and Key Laboratory of Functional Protein Research of Guangdong Higher Education Institutes, Institute of Life and Health Engineering, Jinan University, Guangzhou 510632, China
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6
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Schilcher K, Horswill AR. Staphylococcal Biofilm Development: Structure, Regulation, and Treatment Strategies. Microbiol Mol Biol Rev 2020; 84:e00026-19. [PMID: 32792334 PMCID: PMC7430342 DOI: 10.1128/mmbr.00026-19] [Citation(s) in RCA: 302] [Impact Index Per Article: 75.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
In many natural and clinical settings, bacteria are associated with some type of biotic or abiotic surface that enables them to form biofilms, a multicellular lifestyle with bacteria embedded in an extracellular matrix. Staphylococcus aureus and Staphylococcus epidermidis, the most frequent causes of biofilm-associated infections on indwelling medical devices, can switch between an existence as single free-floating cells and multicellular biofilms. During biofilm formation, cells first attach to a surface and then multiply to form microcolonies. They subsequently produce the extracellular matrix, a hallmark of biofilm formation, which consists of polysaccharides, proteins, and extracellular DNA. After biofilm maturation into three-dimensional structures, the biofilm community undergoes a disassembly process that leads to the dissemination of staphylococcal cells. As biofilms are dynamic and complex biological systems, staphylococci have evolved a vast network of regulatory mechanisms to modify and fine-tune biofilm development upon changes in environmental conditions. Thus, biofilm formation is used as a strategy for survival and persistence in the human host and can serve as a reservoir for spreading to new infection sites. Moreover, staphylococcal biofilms provide enhanced resilience toward antibiotics and the immune response and impose remarkable therapeutic challenges in clinics worldwide. This review provides an overview and an updated perspective on staphylococcal biofilms, describing the characteristic features of biofilm formation, the structural and functional properties of the biofilm matrix, and the most important mechanisms involved in the regulation of staphylococcal biofilm formation. Finally, we highlight promising strategies and technologies, including multitargeted or combinational therapies, to eradicate staphylococcal biofilms.
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Affiliation(s)
- Katrin Schilcher
- Department of Immunology and Microbiology, University of Colorado School of Medicine, Aurora, Colorado, USA
| | - Alexander R Horswill
- Department of Immunology and Microbiology, University of Colorado School of Medicine, Aurora, Colorado, USA
- Department of Veterans Affairs Eastern Colorado Health Care System, Denver, Colorado, USA
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7
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Schilcher K, Horswill AR. Staphylococcal Biofilm Development: Structure, Regulation, and Treatment Strategies. Microbiol Mol Biol Rev 2020. [PMID: 32792334 DOI: 10.1128/mmbr.00026-19/asset/e] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/15/2023] Open
Abstract
In many natural and clinical settings, bacteria are associated with some type of biotic or abiotic surface that enables them to form biofilms, a multicellular lifestyle with bacteria embedded in an extracellular matrix. Staphylococcus aureus and Staphylococcus epidermidis, the most frequent causes of biofilm-associated infections on indwelling medical devices, can switch between an existence as single free-floating cells and multicellular biofilms. During biofilm formation, cells first attach to a surface and then multiply to form microcolonies. They subsequently produce the extracellular matrix, a hallmark of biofilm formation, which consists of polysaccharides, proteins, and extracellular DNA. After biofilm maturation into three-dimensional structures, the biofilm community undergoes a disassembly process that leads to the dissemination of staphylococcal cells. As biofilms are dynamic and complex biological systems, staphylococci have evolved a vast network of regulatory mechanisms to modify and fine-tune biofilm development upon changes in environmental conditions. Thus, biofilm formation is used as a strategy for survival and persistence in the human host and can serve as a reservoir for spreading to new infection sites. Moreover, staphylococcal biofilms provide enhanced resilience toward antibiotics and the immune response and impose remarkable therapeutic challenges in clinics worldwide. This review provides an overview and an updated perspective on staphylococcal biofilms, describing the characteristic features of biofilm formation, the structural and functional properties of the biofilm matrix, and the most important mechanisms involved in the regulation of staphylococcal biofilm formation. Finally, we highlight promising strategies and technologies, including multitargeted or combinational therapies, to eradicate staphylococcal biofilms.
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Affiliation(s)
- Katrin Schilcher
- Department of Immunology and Microbiology, University of Colorado School of Medicine, Aurora, Colorado, USA
| | - Alexander R Horswill
- Department of Immunology and Microbiology, University of Colorado School of Medicine, Aurora, Colorado, USA
- Department of Veterans Affairs Eastern Colorado Health Care System, Denver, Colorado, USA
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8
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Carlson SK, Erickson DL, Wilson E. Staphylococcus aureus metal acquisition in the mastitic mammary gland. Microb Pathog 2020; 144:104179. [DOI: 10.1016/j.micpath.2020.104179] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2019] [Revised: 03/23/2020] [Accepted: 03/27/2020] [Indexed: 12/28/2022]
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9
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Genetic Regulation of Metal Ion Homeostasis in Staphylococcus aureus. Trends Microbiol 2020; 28:821-831. [PMID: 32381454 DOI: 10.1016/j.tim.2020.04.004] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2020] [Revised: 04/01/2020] [Accepted: 04/02/2020] [Indexed: 12/16/2022]
Abstract
The acquisition of metal ions and the proper maturation of holo-metalloproteins are essential processes for all organisms. However, metal ion homeostasis is a double-edged sword. A cytosolic accumulation of metal ions can lead to mismetallation of proteins and cell death. Therefore, maintenance of proper concentrations of intracellular metals is essential for cell fitness and pathogenesis. Staphylococcus aureus, like all bacterial pathogens, uses transcriptional metalloregulatory proteins to aid in the detection and the genetic response to changes in metal ion concentrations. Herein, we review the mechanisms by which S. aureus senses and responds to alterations in the levels of cellular zinc, iron, heme, and copper. The interplay between metal ion sensing and metal-dependent expression of virulence factors is also discussed.
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10
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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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11
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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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12
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Sarvan S, Butcher J, Stintzi A, Couture JF. Variation on a theme: investigating the structural repertoires used by ferric uptake regulators to control gene expression. Biometals 2018; 31:681-704. [DOI: 10.1007/s10534-018-0120-8] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2018] [Accepted: 06/12/2018] [Indexed: 11/29/2022]
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13
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Fojcik C, Arnoux P, Ouerdane L, Aigle M, Alfonsi L, Borezée-Durant E. Independent and cooperative regulation of staphylopine biosynthesis and trafficking by Fur and Zur. Mol Microbiol 2018; 108:159-177. [DOI: 10.1111/mmi.13927] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 02/07/2018] [Indexed: 11/25/2022]
Affiliation(s)
- Clémentine Fojcik
- Micalis Institute, INRA, AgroParisTech; University Paris-Saclay; 78350 Jouy-en-Josas France
| | - Pascal Arnoux
- CEA, DRF, BIAM, Laboratoire de Bioénergétique Cellulaire; Saint-Paul-lez-Durance France
- CNRS, UMR 7265 Biologie Végétale et Microbiologie Environnementales; Saint-Paul-lez-Durance France
- Aix Marseille Université, UMR 7265 Biologie Végétale et Microbiologie Environnementales; Saint Paul-Lez-Durance 13108 France
| | - Laurent Ouerdane
- CNRS-UPPA, Laboratoire de Chimie Analytique Bio-inorganique et Environnement, UMR 5254, Hélioparc, 2; Av. Angot 64053 Pau France
| | - Marina Aigle
- Micalis Institute, INRA, AgroParisTech; University Paris-Saclay; 78350 Jouy-en-Josas France
| | - Laura Alfonsi
- Micalis Institute, INRA, AgroParisTech; University Paris-Saclay; 78350 Jouy-en-Josas France
| | - Elise Borezée-Durant
- Micalis Institute, INRA, AgroParisTech; University Paris-Saclay; 78350 Jouy-en-Josas France
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14
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Lojek LJ, Farrand AJ, Weiss A, Skaar EP. Fur regulation of Staphylococcus aureus heme oxygenases is required for heme homeostasis. Int J Med Microbiol 2018; 308:582-589. [PMID: 29409696 DOI: 10.1016/j.ijmm.2018.01.009] [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: 07/25/2017] [Revised: 01/04/2018] [Accepted: 01/27/2018] [Indexed: 01/23/2023] Open
Abstract
Heme is a cofactor that is essential for cellular respiration and for the function of many enzymes. If heme levels become too low within the cell, S. aureus switches from producing energy via respiration to producing energy by fermentation. S. aureus encodes two heme oxygenases, IsdI and IsdG, which cleave the porphyrin heme ring releasing iron for use as a nutrient source. Both isdI and isdG are only expressed under low iron conditions and are regulated by the canonical Ferric Uptake Regulator (Fur). Here we demonstrate that unregulated expression of isdI and isdG within S. aureus leads to reduced growth under low iron conditions. Additionally, the constitutive expression of these enzymes leads to decreased heme abundance in S. aureus, an increase in the fermentation product lactate, and increased resistance to gentamicin. This work demonstrates that S. aureus has developed tuning mechanisms, such as Fur regulation, to ensure that the cell has sufficient quantities of heme for efficient ATP production through aerobic respiration.
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Affiliation(s)
- Lisa J Lojek
- Department of Pathology, Microbiology & Immunology, Vanderbilt University Medical Center, Nashville, TN, 37232, USA; Graduate Program in Microbiology & Immunology, Vanderbilt University, Nashville, TN, 37232, USA
| | - Allison J Farrand
- Department of Pathology, Microbiology & Immunology, Vanderbilt University Medical Center, Nashville, TN, 37232, USA
| | - Andy Weiss
- Department of Pathology, Microbiology & Immunology, Vanderbilt University Medical Center, Nashville, TN, 37232, USA
| | - Eric P Skaar
- Department of Pathology, Microbiology & Immunology, Vanderbilt University Medical Center, Nashville, TN, 37232, USA.
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15
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Casabona MG, Kneuper H, Alferes de Lima D, Harkins CP, Zoltner M, Hjerde E, Holden MTG, Palmer T. Haem-iron plays a key role in the regulation of the Ess/type VII secretion system of Staphylococcus aureus RN6390. MICROBIOLOGY-SGM 2017; 163:1839-1850. [PMID: 29171824 PMCID: PMC5845736 DOI: 10.1099/mic.0.000579] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
The Staphylococcus aureus type VII protein secretion system (T7SS) plays important roles in virulence and intra-species competition. Here we show that the T7SS in strain RN6390 is activated by supplementing the growth medium with haemoglobin, and its cofactor haemin (haem B). Transcript analysis and secretion assays suggest that activation by haemin occurs at a transcriptional and a post-translational level. Loss of T7 secretion activity by deletion of essC results in upregulation of genes required for iron acquisition. Taken together these findings suggest that the T7SS plays a role in iron homeostasis in at least some S. aureus strains.
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Affiliation(s)
- M Guillermina Casabona
- Division of Molecular Microbiology School of Life Sciences, University of Dundee, Dundee, UK
| | - Holger Kneuper
- Division of Molecular Microbiology School of Life Sciences, University of Dundee, Dundee, UK
| | - Daniela Alferes de Lima
- Division of Molecular Microbiology School of Life Sciences, University of Dundee, Dundee, UK
| | | | - Martin Zoltner
- Division of Molecular Microbiology School of Life Sciences, University of Dundee, Dundee, UK
| | - Erik Hjerde
- Department of Chemistry, Arctic University of Norway, Tromsø, Norway
| | | | - Tracy Palmer
- Division of Molecular Microbiology School of Life Sciences, University of Dundee, Dundee, UK
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16
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Balasubramanian D, Harper L, Shopsin B, Torres VJ. Staphylococcus aureus pathogenesis in diverse host environments. Pathog Dis 2017; 75:ftx005. [PMID: 28104617 DOI: 10.1093/femspd/ftx005] [Citation(s) in RCA: 143] [Impact Index Per Article: 20.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2016] [Accepted: 01/18/2017] [Indexed: 12/21/2022] Open
Abstract
Staphylococcus aureus is an eminent human pathogen that can colonize the human host and cause severe life-threatening illnesses. This bacterium can reside in and infect a wide range of host tissues, ranging from superficial surfaces like the skin to deeper tissues such as in the gastrointestinal tract, heart and bones. Due to its multifaceted lifestyle, S. aureus uses complex regulatory networks to sense diverse signals that enable it to adapt to different environments and modulate virulence. In this minireview, we explore well-characterized environmental and host cues that S. aureus responds to and describe how this pathogen modulates virulence in response to these signals. Lastly, we highlight therapeutic approaches undertaken by several groups to inhibit both signaling and the cognate regulators that sense and transmit these signals downstream.
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Affiliation(s)
- Divya Balasubramanian
- Department of Microbiology, New York University School of Medicine, New York, NY 10016, USA
| | - Lamia Harper
- Department of Microbiology, New York University School of Medicine, New York, NY 10016, USA
| | - Bo Shopsin
- Department of Medicine, Division of Infectious Diseases, New York University School of Medicine, New York, NY 10016 USA
| | - Victor J Torres
- Department of Microbiology, New York University School of Medicine, New York, NY 10016, USA
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17
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Regulatory Requirements for Staphylococcus aureus Nitric Oxide Resistance. J Bacteriol 2016; 198:2043-55. [PMID: 27185828 DOI: 10.1128/jb.00229-16] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2016] [Accepted: 05/10/2016] [Indexed: 12/12/2022] Open
Abstract
UNLABELLED The ability of Staphylococcus aureus to resist host innate immunity augments the severity and pervasiveness of its pathogenesis. Nitric oxide (NO˙) is an innate immune radical that is critical for the efficient clearance of a wide range of microbial pathogens. Exposure of microbes to NO˙ typically results in growth inhibition and induction of stress regulons. S. aureus, however, induces a metabolic state in response to NO˙ that allows for continued replication and precludes stress regulon induction. The regulatory factors mediating this distinctive response remain largely undefined. Here, we employ a targeted transposon screen and transcriptomics to identify and characterize five regulons essential for NO˙ resistance in S. aureus: three virulence regulons not formerly associated with NO˙ resistance, SarA, CodY, and Rot, as well as two regulons with established roles, Fur and SrrAB. We provide new insights into the contributions of Fur and SrrAB during NO˙ stress and show that the S. aureus ΔsarA mutant, the most sensitive of the newly identified mutants, exhibits metabolic dysfunction and widespread transcriptional dysregulation following NO˙ exposure. Altogether, our results broadly characterize the regulatory requirements for NO˙ resistance in S. aureus and suggest an intriguing overlap between the regulation of NO˙ resistance and virulence in this well-adapted human pathogen. IMPORTANCE The prolific human pathogen Staphylococcus aureus is uniquely capable of resisting the antimicrobial radical nitric oxide (NO˙), a crucial component of the innate immune response. However, a complete understanding of how S. aureus regulates an effective response to NO˙ is lacking. Here, we implicate three central virulence regulators, SarA, CodY, and Rot, as major players in the S. aureus NO˙ response. Additionally, we elaborate on the contribution of two regulators, SrrAB and Fur, already known to play a crucial role in S. aureus NO˙ resistance. Our study sheds light on a unique facet of S. aureus pathogenicity and demonstrates that the transcriptional response of S. aureus to NO˙ is highly pleiotropic and intrinsically tied to metabolism and virulence regulation.
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Silica-Induced Protein (Sip) in Thermophilic Bacterium Thermus thermophilus Responds to Low Iron Availability. Appl Environ Microbiol 2016; 82:3198-3207. [PMID: 26994077 DOI: 10.1128/aem.04027-15] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2015] [Accepted: 03/14/2016] [Indexed: 12/22/2022] Open
Abstract
UNLABELLED Thermus thermophilus HB8 expresses silica-induced protein (Sip) when cultured in medium containing supersaturated silicic acids. Using genomic information, Sip was identified as a Fe(3+)-binding ABC transporter. Detection of a 1-kb hybridized band in Northern analysis revealed that sip transcription is monocistronic and that sip has its own terminator and promoter. The sequence of the sip promoter showed homology with that of the σ(A)-dependent promoter, which is known as a housekeeping promoter in HB8. Considering that sip is transcribed when supersaturated silicic acids are added, the existence of a repressor is presumed. DNA microarray analysis suggested that supersaturated silicic acids and iron deficiency affect Thermus cells similarly, and enhanced sip transcription was detected under both conditions. This suggested that sip transcription was initiated by iron deficiency and that the ferric uptake regulator (Fur) controlled the transcription. Three Fur gene homologues (TTHA0255, TTHA0344, and TTHA1292) have been annotated in the HB8 genome, and electrophoretic mobility shift assays revealed that the TTHA0344 product interacts with the sip promoter region. In medium containing supersaturated silicic acids, free Fe(3+) levels were decreased due to Fe(3+) immobilization on colloidal silica. This suggests that, because Fe(3+) ions are captured by colloidal silica in geothermal water, Thermus cells are continuously exposed to the risk of iron deficiency. Considering that Sip is involved in iron acquisition, Sip production may be a strategy to survive under conditions of low iron availability in geothermal water. IMPORTANCE The thermophilic bacterium Thermus thermophilus HB8 produces silica-induced protein (Sip) in the presence of supersaturated silicic acids. Sip has homology with iron-binding ABC transporter; however, the mechanism by which Sip expression is induced by silicic acids remains unexplained. We demonstrate that Sip captures iron and its transcription is regulated by the repressor ferric uptake regulator (Fur). This implies that Sip is expressed with iron deficiency. In addition, it is suggested that negatively charged colloidal silica in supersaturated solution absorbs Fe(3+) ions and decreases iron availability. Considering that geothermal water contains ample silicic acids, it is suggested that thermophilic bacteria are always facing iron starvation. Sip production may be a strategy for surviving under conditions of low iron availability in geothermal water.
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Mäder U, Nicolas P, Depke M, Pané-Farré J, Debarbouille M, van der Kooi-Pol MM, Guérin C, Dérozier S, Hiron A, Jarmer H, Leduc A, Michalik S, Reilman E, Schaffer M, Schmidt F, Bessières P, Noirot P, Hecker M, Msadek T, Völker U, van Dijl JM. Staphylococcus aureus Transcriptome Architecture: From Laboratory to Infection-Mimicking Conditions. PLoS Genet 2016; 12:e1005962. [PMID: 27035918 PMCID: PMC4818034 DOI: 10.1371/journal.pgen.1005962] [Citation(s) in RCA: 134] [Impact Index Per Article: 16.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2015] [Accepted: 03/04/2016] [Indexed: 11/18/2022] Open
Abstract
Staphylococcus aureus is a major pathogen that colonizes about 20% of the human population. Intriguingly, this Gram-positive bacterium can survive and thrive under a wide range of different conditions, both inside and outside the human body. Here, we investigated the transcriptional adaptation of S. aureus HG001, a derivative of strain NCTC 8325, across experimental conditions ranging from optimal growth in vitro to intracellular growth in host cells. These data establish an extensive repertoire of transcription units and non-coding RNAs, a classification of 1412 promoters according to their dependence on the RNA polymerase sigma factors SigA or SigB, and allow identification of new potential targets for several known transcription factors. In particular, this study revealed a relatively low abundance of antisense RNAs in S. aureus, where they overlap only 6% of the coding genes, and only 19 antisense RNAs not co-transcribed with other genes were found. Promoter analysis and comparison with Bacillus subtilis links the small number of antisense RNAs to a less profound impact of alternative sigma factors in S. aureus. Furthermore, we revealed that Rho-dependent transcription termination suppresses pervasive antisense transcription, presumably originating from abundant spurious transcription initiation in this A+T-rich genome, which would otherwise affect expression of the overlapped genes. In summary, our study provides genome-wide information on transcriptional regulation and non-coding RNAs in S. aureus as well as new insights into the biological function of Rho and the implications of spurious transcription in bacteria. The major human pathogen Staphylococcus aureus can survive under a wide range of conditions, both inside and outside the human body. The goal of this study was to determine how S. aureus adapts to such different conditions and, additionally, we wanted to identify general factors governing the staphylococcal transcriptome architecture. Therefore, we performed a precise analysis of all RNA transcripts of S. aureus across experimental conditions ranging from in vitro growth in different media to internalization by eukaryotic host cells. We systematically mapped all transcription units, annotated non-coding RNAs, and assigned promoters controlled by particular RNA polymerase sigma factors and transcription factors. By a comparison with data available for the related Gram-positive bacterium Bacillus subtilis, we made key observations concerning the abundance and origin of antisense RNAs. Intriguingly, these findings support the view that many antisense RNAs in a bacterium like B. subtilis could be byproducts of spurious promoter recognition by condition-specific alternative sigma factors. We also report that the transcription termination factor Rho prevents widespread antisense transcription, presumably caused by pervasive transcription initiation in the A+T-rich genome of S. aureus. Altogether our study presents new perspectives on the biological significance of antisense and pervasive transcription in bacteria.
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Affiliation(s)
- Ulrike Mäder
- Interfaculty Institute for Genetics and Functional Genomics, University Medicine Greifswald, Greifswald, Germany
| | - Pierre Nicolas
- MaIAGE, INRA, Université Paris-Saclay, Jouy-en-Josas, France
| | - Maren Depke
- Interfaculty Institute for Genetics and Functional Genomics, University Medicine Greifswald, Greifswald, Germany
| | - Jan Pané-Farré
- Institute for Microbiology, Ernst-Moritz-Arndt-University Greifswald, Greifswald, Germany
| | - Michel Debarbouille
- Biology of Gram-Positive Pathogens, Department of Microbiology, Institut Pasteur and CNRS ERL 3526, Paris, France
| | - Magdalena M. van der Kooi-Pol
- Department of Medical Microbiology, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands
| | - Cyprien Guérin
- MaIAGE, INRA, Université Paris-Saclay, Jouy-en-Josas, France
| | - Sandra Dérozier
- MaIAGE, INRA, Université Paris-Saclay, Jouy-en-Josas, France
| | - Aurelia Hiron
- Biology of Gram-Positive Pathogens, Department of Microbiology, Institut Pasteur and CNRS ERL 3526, Paris, France
| | - Hanne Jarmer
- Center for Biological Sequence Analysis, Department of Systems Biology, Technical University of Denmark, Kongens Lyngby, Denmark
| | - Aurélie Leduc
- MaIAGE, INRA, Université Paris-Saclay, Jouy-en-Josas, France
| | - Stephan Michalik
- Interfaculty Institute for Genetics and Functional Genomics, University Medicine Greifswald, Greifswald, Germany
| | - Ewoud Reilman
- Department of Medical Microbiology, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands
| | - Marc Schaffer
- Interfaculty Institute for Genetics and Functional Genomics, University Medicine Greifswald, Greifswald, Germany
| | - Frank Schmidt
- Interfaculty Institute for Genetics and Functional Genomics, University Medicine Greifswald, Greifswald, Germany
| | | | - Philippe Noirot
- Institut Micalis, INRA and AgroParisTech, Jouy-en-Josas, France
| | - Michael Hecker
- Institute for Microbiology, Ernst-Moritz-Arndt-University Greifswald, Greifswald, Germany
| | - Tarek Msadek
- Biology of Gram-Positive Pathogens, Department of Microbiology, Institut Pasteur and CNRS ERL 3526, Paris, France
| | - Uwe Völker
- Interfaculty Institute for Genetics and Functional Genomics, University Medicine Greifswald, Greifswald, Germany
- * E-mail: (UV); (JMvD)
| | - Jan Maarten van Dijl
- Department of Medical Microbiology, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands
- * E-mail: (UV); (JMvD)
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20
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Kaushik MS, Singh P, Tiwari B, Mishra AK. Ferric Uptake Regulator (FUR) protein: properties and implications in cyanobacteria. ANN MICROBIOL 2015. [DOI: 10.1007/s13213-015-1134-x] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
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21
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Mashruwala AA, Pang YY, Rosario-Cruz Z, Chahal HK, Benson MA, Anzaldi-Mike LL, Skaar EP, Torres VJ, Nauseef WM, Boyd JM. Nfu facilitates the maturation of iron-sulfur proteins and participates in virulence in Staphylococcus aureus. Mol Microbiol 2015; 95:383-409. [PMID: 25388433 PMCID: PMC4428306 DOI: 10.1111/mmi.12860] [Citation(s) in RCA: 54] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/06/2014] [Indexed: 01/21/2023]
Abstract
The acquisition and metabolism of iron (Fe) by the human pathogen Staphylococcus aureus is critical for disease progression. S. aureus requires Fe to synthesize inorganic cofactors called iron-sulfur (Fe-S) clusters, which are required for functional Fe-S proteins. In this study we investigated the mechanisms utilized by S. aureus to metabolize Fe-S clusters. We identified that S. aureus utilizes the Suf biosynthetic system to synthesize Fe-S clusters and we provide genetic evidence suggesting that the sufU and sufB gene products are essential. Additional biochemical and genetic analyses identified Nfu as an Fe-S cluster carrier, which aids in the maturation of Fe-S proteins. We find that deletion of the nfu gene negatively impacts staphylococcal physiology and pathogenicity. A nfu mutant accumulates both increased intracellular non-incorporated Fe and endogenous reactive oxygen species (ROS) resulting in DNA damage. In addition, a strain lacking Nfu is sensitive to exogenously supplied ROS and reactive nitrogen species. Congruous with ex vivo findings, a nfu mutant strain is more susceptible to oxidative killing by human polymorphonuclear leukocytes and displays decreased tissue colonization in a murine model of infection. We conclude that Nfu is necessary for staphylococcal pathogenesis and establish Fe-S cluster metabolism as an attractive antimicrobial target.
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Affiliation(s)
- Ameya A. Mashruwala
- Department of Biochemistry and Microbiology, Rutgers University, New Brunswick, NJ 08901
| | - Yun Y. Pang
- Inflammation Program and Department of Internal Medicine, Roy J. and Lucille A. Carver College of Medicine, University of Iowa, and Veterans Administration Medical Center, Iowa City, IA 52240
| | - Zuelay Rosario-Cruz
- Department of Biochemistry and Microbiology, Rutgers University, New Brunswick, NJ 08901
| | - Harsimranjit K. Chahal
- Department of Biochemistry and Microbiology, Rutgers University, New Brunswick, NJ 08901
| | - Meredith A. Benson
- Department of Microbiology, NYU Langone Medical Center, New York, NY 10016
| | - Laura L. Anzaldi-Mike
- Department of Pathology, Microbiology, and Immunology, Vanderbilt University School of Medicine, Nashville, TN 37232
| | - Eric P. Skaar
- Department of Pathology, Microbiology, and Immunology, Vanderbilt University School of Medicine, Nashville, TN 37232
| | - Victor J. Torres
- Department of Microbiology, NYU Langone Medical Center, New York, NY 10016
| | - William M. Nauseef
- Inflammation Program and Department of Internal Medicine, Roy J. and Lucille A. Carver College of Medicine, University of Iowa, and Veterans Administration Medical Center, Iowa City, IA 52240
| | - Jeffrey M. Boyd
- Department of Biochemistry and Microbiology, Rutgers University, New Brunswick, NJ 08901
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22
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Tiwari KB, Birlingmair J, Wilkinson BJ, Jayaswal RK. Role of the twin-arginine translocase (tat) system in iron uptake in Listeria monocytogenes. Microbiology (Reading) 2015; 161:264-271. [DOI: 10.1099/mic.0.083642-0] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Affiliation(s)
- Kiran B. Tiwari
- School of Biological Sciences, Illinois State University, Normal, IL, USA
| | - Jacob Birlingmair
- School of Biological Sciences, Illinois State University, Normal, IL, USA
| | - Brian J. Wilkinson
- School of Biological Sciences, Illinois State University, Normal, IL, USA
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23
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Sheldon JR, Marolda CL, Heinrichs DE. TCA cycle activity in Staphylococcus aureus is essential for iron-regulated synthesis of staphyloferrin A, but not staphyloferrin B: the benefit of a second citrate synthase. Mol Microbiol 2014; 92:824-39. [PMID: 24666349 DOI: 10.1111/mmi.12593] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/25/2014] [Indexed: 02/06/2023]
Abstract
Staphylococcus aureus elaborates two citrate-containing siderophores, staphyloferrin A (SA) and staphyloferrin B (SB), that enhance growth under iron-restriction, yet, paradoxically, expression of the TCA cycle citrate synthase, CitZ, is downregulated during iron starvation. Iron starvation does, however, result in expression of SbnG, recently identified as a novel citrate synthase that is encoded from within the iron-regulated SB biosynthetic locus, suggesting an important role for SbnG in staphyloferrin production. We demonstrate that during growth of S. aureus in iron-restricted media containing glucose, SB is produced but, in contrast, SA production is severely repressed; accordingly, SB-deficient mutants grow poorly in these media. Hypothesizing that reduced TCA cycle activity hinders SA production, we show that a citZ mutant is capable of SB synthesis, but not SA synthesis, providing evidence that SbnG does not generate citrate for incorporation into SA. A citZ sbnG mutant synthesizes neither staphyloferrin, is severely compromised for growth in iron-restricted media, and is significantly more impaired for virulence than either of the single-deletion mutants. We propose that SB is the more important of the two siderophores for S. aureus insofar as it is synthesized, and supports iron-restricted growth, without need of TCA cycle activity.
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Affiliation(s)
- Jessica R Sheldon
- Department of Microbiology and Immunology, University of Western Ontario, London, ON, Canada
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24
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Kobylarz MJ, Grigg JC, Takayama SIJ, Rai DK, Heinrichs DE, Murphy MEP. Synthesis of L-2,3-diaminopropionic acid, a siderophore and antibiotic precursor. ACTA ACUST UNITED AC 2014; 21:379-88. [PMID: 24485762 DOI: 10.1016/j.chembiol.2013.12.011] [Citation(s) in RCA: 53] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2013] [Revised: 12/03/2013] [Accepted: 12/07/2013] [Indexed: 11/29/2022]
Abstract
L-2,3-diaminopropionic acid (L-Dap) is an amino acid that is a precursor of antibiotics and staphyloferrin B a siderophore produced by Staphylococcus aureus. SbnA and SbnB are encoded by the staphyloferrin B biosynthetic gene cluster and are implicated in L-Dap biosynthesis. We demonstrate here that SbnA uses PLP and substrates O-phospho-L-serine and L-glutamate to produce a metabolite N-(1-amino-1-carboxyl-2-ethyl)-glutamic acid (ACEGA). SbnB is shown to use NAD(+) to oxidatively hydrolyze ACEGA to yield α-ketoglutarate and L-Dap. Also, we describe crystal structures of SbnB in complex with NADH and ACEGA as well as with NAD(+) and α-ketoglutarate to reveal the residues required for substrate binding, oxidation, and hydrolysis. SbnA and SbnB contribute to the iron sparing response of S. aureus that enables staphyloferrin B biosynthesis in the absence of an active tricarboxylic acid cycle.
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Affiliation(s)
- Marek J Kobylarz
- Department of Microbiology and Immunology, Life Sciences Institute, The University of British Columbia, Vancouver, BC V6T 1Z3, Canada
| | - Jason C Grigg
- Department of Microbiology and Immunology, Life Sciences Institute, The University of British Columbia, Vancouver, BC V6T 1Z3, Canada
| | - Shin-ichi J Takayama
- Department of Microbiology and Immunology, Life Sciences Institute, The University of British Columbia, Vancouver, BC V6T 1Z3, Canada
| | - Dushyant K Rai
- Department of Microbiology and Immunology, Life Sciences Institute, The University of British Columbia, Vancouver, BC V6T 1Z3, Canada
| | - David E Heinrichs
- Department of Microbiology and Immunology, The Centre for Human Immunology, University of Western Ontario, London, ON N6A 5C1, Canada
| | - Michael E P Murphy
- Department of Microbiology and Immunology, Life Sciences Institute, The University of British Columbia, Vancouver, BC V6T 1Z3, Canada.
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25
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High Level Expression and Purification of Atl, the Major Autolytic Protein of Staphylococcus aureus. Int J Microbiol 2014; 2014:615965. [PMID: 24669224 PMCID: PMC3941666 DOI: 10.1155/2014/615965] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2013] [Revised: 09/16/2013] [Accepted: 10/24/2013] [Indexed: 11/19/2022] Open
Abstract
Staphylococcus aureus is a major human and animal pathogen. Autolysins regulate the growth, turnover, cell lysis, biofilm formation, and the pathogenicity of S. aureus. Atl is the major autolysin in S. aureus. The biochemical and structural studies of staphylococcal Atl have been limited due to difficulty in cloning, high level overexpression, and purification of this protein. This study describes successful cloning, high level over-expression, and purification of two forms of fully functional Atl proteins. These pure proteins can be used to study the functional and structural properties of this important protein.
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26
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Krismer B, Liebeke M, Janek D, Nega M, Rautenberg M, Hornig G, Unger C, Weidenmaier C, Lalk M, Peschel A. Nutrient limitation governs Staphylococcus aureus metabolism and niche adaptation in the human nose. PLoS Pathog 2014; 10:e1003862. [PMID: 24453967 PMCID: PMC3894218 DOI: 10.1371/journal.ppat.1003862] [Citation(s) in RCA: 124] [Impact Index Per Article: 12.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2013] [Accepted: 11/18/2013] [Indexed: 01/23/2023] Open
Abstract
Colonization of the human nose by Staphylococcus aureus in one-third of the population represents a major risk factor for invasive infections. The basis for adaptation of S. aureus to this specific habitat and reasons for the human predisposition to become colonized have remained largely unknown. Human nasal secretions were analyzed by metabolomics and found to contain potential nutrients in rather low amounts. No significant differences were found between S. aureus carriers and non-carriers, indicating that carriage is not associated with individual differences in nutrient supply. A synthetic nasal medium (SNM3) was composed based on the metabolomics data that permits consistent growth of S. aureus isolates. Key genes were expressed in SNM3 in a similar way as in the human nose, indicating that SNM3 represents a suitable surrogate environment for in vitro simulation studies. While the majority of S. aureus strains grew well in SNM3, most of the tested coagulase-negative staphylococci (CoNS) had major problems to multiply in SNM3 supporting the notion that CoNS are less well adapted to the nose and colonize preferentially the human skin. Global gene expression analysis revealed that, during growth in SNM3, S. aureus depends heavily on de novo synthesis of methionine. Accordingly, the methionine-biosynthesis enzyme cysteine-γ-synthase (MetI) was indispensable for growth in SNM3, and the MetI inhibitor DL-propargylglycine inhibited S. aureus growth in SNM3 but not in the presence of methionine. Of note, metI was strongly up-regulated by S. aureus in human noses, and metI mutants were strongly abrogated in their capacity to colonize the noses of cotton rats. These findings indicate that the methionine biosynthetic pathway may include promising antimicrobial targets that have previously remained unrecognized. Hence, exploring the environmental conditions facultative pathogens are exposed to during colonization can be useful for understanding niche adaptation and identifying targets for new antimicrobial strategies.
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Affiliation(s)
- Bernhard Krismer
- Interfaculty Institute of Microbiology and Infection Medicine, Cellular and Molecular Microbiology, Eberhard-Karls-University Tübingen, Tübingen, Germany
- German Center for Infection Research (DZIF), partner site Tübingen, Tübingen, Germany
- * E-mail:
| | - Manuel Liebeke
- Institute of Pharmacy, Ernst-Moritz-Arndt University of Greifswald, Greifswald, Germany
| | - Daniela Janek
- Interfaculty Institute of Microbiology and Infection Medicine, Cellular and Molecular Microbiology, Eberhard-Karls-University Tübingen, Tübingen, Germany
- German Center for Infection Research (DZIF), partner site Tübingen, Tübingen, Germany
| | - Mulugeta Nega
- Interfaculty Institute of Microbiology and Infection Medicine, Microbial Genetics, Eberhard-Karls-University Tübingen, Tübingen, Germany
| | - Maren Rautenberg
- Interfaculty Institute of Microbiology and Infection Medicine, Cellular and Molecular Microbiology, Eberhard-Karls-University Tübingen, Tübingen, Germany
- German Center for Infection Research (DZIF), partner site Tübingen, Tübingen, Germany
| | - Gabriele Hornig
- Interfaculty Institute of Microbiology and Infection Medicine, Cellular and Molecular Microbiology, Eberhard-Karls-University Tübingen, Tübingen, Germany
- German Center for Infection Research (DZIF), partner site Tübingen, Tübingen, Germany
| | - Clemens Unger
- Institute for Tropical Medicine, University of Tübingen, Tübingen, Germany
| | - Christopher Weidenmaier
- Interfaculty Institute of Microbiology and Infection Medicine, Cellular and Molecular Microbiology, Eberhard-Karls-University Tübingen, Tübingen, Germany
- German Center for Infection Research (DZIF), partner site Tübingen, Tübingen, Germany
| | - Michael Lalk
- Institute of Pharmacy, Ernst-Moritz-Arndt University of Greifswald, Greifswald, Germany
| | - Andreas Peschel
- Interfaculty Institute of Microbiology and Infection Medicine, Cellular and Molecular Microbiology, Eberhard-Karls-University Tübingen, Tübingen, Germany
- German Center for Infection Research (DZIF), partner site Tübingen, Tübingen, Germany
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27
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Dauros-Singorenko P, Swift S. The transition from iron starvation to iron sufficiency as an important step in the progression of infection. Sci Prog 2014; 97:371-82. [PMID: 25638949 PMCID: PMC10365408 DOI: 10.3184/003685014x14151846374739] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
Iron is an essential micronutrient for microbial life. At the start of an infection the host environment will normally restrict available iron, and innate immune responses will aim to further reduce iron, thus inhibiting growth of potential pathogens. Successful pathogens have developed a variety of mechanisms to acquire iron from the available in vivo sources, using remote and direct capture, to render their environment iron replete. Iron restriction, and the presence of host iron sources like haem, are important drivers of gene regulation controlling the expression of numerous virulence factors. As an infection progresses the changing iron environment will therefore influence pathogen gene expression and trigger new activities. Understanding how bacteria acquire iron, and how iron acquisition affects the bacteria, has identified vaccine and antibiotic drug targets and is now suggesting novel approaches to control and treat infection.
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Affiliation(s)
| | - Simon Swift
- Molecular Medicine and Pathology, Faculty of Medical and Health Sciences, University of Auckland, Private Bag 92019, Auckland, New Zealand
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28
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Loutet SA, Kobylarz MJ, Chau CHT, Murphy MEP. IruO is a reductase for heme degradation by IsdI and IsdG proteins in Staphylococcus aureus. J Biol Chem 2013; 288:25749-25759. [PMID: 23893407 DOI: 10.1074/jbc.m113.470518] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023] Open
Abstract
Staphylococcus aureus is a common hospital- and community-acquired bacterium that can cause devastating infections and is often multidrug-resistant. Iron acquisition is required by S. aureus during an infection, and iron acquisition pathways are potential targets for therapies. The gene NWMN2274 in S. aureus strain Newman is annotated as an oxidoreductase of the diverse pyridine nucleotide-disulfide oxidoreductase (PNDO) family. We show that NWMN2274 is an electron donor to IsdG and IsdI catalyzing the degradation of heme, and we have renamed this protein IruO. Recombinant IruO is a FAD-containing NADPH-dependent reductase. In the presence of NADPH and IruO, either IsdI or IsdG degraded bound heme 10-fold more rapidly than with the chemical reductant ascorbic acid. Varying IsdI-heme substrate and monitoring loss of the heme Soret band gave a K(m) of 15 ± 4 μM, a k(cat) of 5.2 ± 0.7 min(-1), and a k(cat)/K(m) of 5.8 × 10(3) M(-1) s(-1). From HPLC and electronic spectra, the major heme degradation products are 5-oxo-δ-bilirubin and 15-oxo-β-bilirubin (staphylobilins), as observed with ascorbic acid. Although heme degradation by IsdI or IsdG can occur in the presence of H2O2, the addition of catalase and superoxide dismutase did not disrupt NADPH/IruO heme degradation reactions. The degree of electron coupling between IruO and IsdI or IsdG remains to be determined. Homologs of IruO were identified by sequence similarity in the genomes of Gram-positive bacteria that possess IsdG-family heme oxygenases. A phylogeny of these homologs identifies a distinct clade of pyridine nucleotide-disulfide oxidoreductases likely involved in iron uptake systems. IruO is the likely in vivo reductant required for heme degradation by S. aureus.
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Affiliation(s)
- Slade A Loutet
- From the Department of Microbiology and Immunology, Life Sciences Institute, The University of British Columbia, Vancouver, British Columbia V6T 1Z3, Canada
| | - Marek J Kobylarz
- From the Department of Microbiology and Immunology, Life Sciences Institute, The University of British Columbia, Vancouver, British Columbia V6T 1Z3, Canada
| | - Crystal H T Chau
- From the Department of Microbiology and Immunology, Life Sciences Institute, The University of British Columbia, Vancouver, British Columbia V6T 1Z3, Canada
| | - Michael E P Murphy
- From the Department of Microbiology and Immunology, Life Sciences Institute, The University of British Columbia, Vancouver, British Columbia V6T 1Z3, Canada.
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Ikeda Y, Minoshima H, Satoh M, Ishikawa T, Kawashima-Ohya Y, Tomobe K, Omata Y, Kawashima T. Transcriptional factor fur from Thermoplasma volcanium binds its own promoter DNA in a divalent cation-dependent manner. J GEN APPL MICROBIOL 2013; 58:465-73. [PMID: 23337582 DOI: 10.2323/jgam.58.465] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
Because archaea possess many respiratory enzymes or radical scavengers with catalytic domains that contain iron, the expression of the genes encoding these enzymes might be regulated by iron acquisition. The genome of an archaeon, Thermoplasma volcanium contains a gene that encodes Fur (TVN0292). The fur gene of T. volcanium was amplified by PCR, and cloned into plasmid pET28a. TvFur (T. volcanium Fur protein) was expressed in E. coli cells and then purified. EMSA revealed that TvFur binds to its own promoter DNA. The binding to its own promoter was in an Mn(2+)-, Zn(2+)-, and Ni(2+)-dependent manner. DNase I footprinting analysis revealed that the binding sequence of tvfur promoter was 5'-G TTATTAT G TTTATAT A TTAATTA G-3'. An analysis utilizing oligonucleotides in TvFur-binding sequences revealed that TvFur binds to the TATA-box or regions in the vicinity of the TATA-box in the promoter. These results indicated that TvFur regulates transcription depending on the availability of environmental divalent cations.
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Affiliation(s)
- Yu Ikeda
- Department of Molecular Biology, Faculty of Pharmaceutical Science, Yokohama College of Pharmacy, Yokohama 245-0066, Japan
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Staphylococcus aureus NorD, a putative efflux pump coregulated with the Opp1 oligopeptide permease, contributes selectively to fitness in vivo. J Bacteriol 2012; 194:6586-93. [PMID: 23042988 DOI: 10.1128/jb.01414-12] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Staphylococcus aureus readily infects humans, causing infections from mild superficial skin infections to lethal bacteremia and endocarditis. Transporters produced by S. aureus allow the pathogen to adapt to a variety of settings, including survival at sites of infection and in the presence of antibiotics. The native functions of many transporters are unknown, but their potential dual contribution to fitness and antimicrobial resistance highlights their importance in staphylococcal infections. Here, we show that S. aureus NorD, a newly recognized efflux pump of the major facilitator superfamily, contributes to fitness in a murine subcutaneous abscess model. In community-associated methicillin-resistant S. aureus (CA-MRSA) strain MW2, norD was selectively upregulated 36-fold at the infection site relative to growth in vitro, and the norD mutant demonstrated significant fitness impairment in abscesses, with fitness 20- to 40-fold lower than that of the parent MW2 strain. Plasmid-encoded NorD could complement the fitness defect of the MW2 norD mutant. Chromosomal norD expression is polycistronic with the upstream oligopeptide permease genes (opp1ABCDF), which encode an ABC oligopeptide transporter. Both norD and opp1 were upregulated in abscesses and iron-restricted culture medium and negatively regulated by Fur, but only NorD contributed to fitness in the murine abscess model.
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Abstract
The ferric uptake regulator (Fur) protein has been shown to function as a repressor of transcription in a number of diverse microorganisms. However, recent studies have established that Fur can function at a global level as both an activator and a repressor of transcription through both direct and indirect mechanisms. Fur-mediated indirect activation occurs via the repression of additional repressor proteins, or small regulatory RNAs, thereby activating transcription of a previously silent gene. Fur mediates direct activation through binding of Fur to the promoter regions of genes. Whereas the repressive mechanism of Fur has been thoroughly investigated, emerging studies on direct and indirect Fur-mediated activation mechanisms have revealed novel global regulatory circuits.
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Saha R, Saha N, Donofrio RS, Bestervelt LL. Microbial siderophores: a mini review. J Basic Microbiol 2012; 53:303-17. [PMID: 22733623 DOI: 10.1002/jobm.201100552] [Citation(s) in RCA: 215] [Impact Index Per Article: 17.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2011] [Accepted: 01/20/2012] [Indexed: 01/22/2023]
Abstract
Iron is one of the major limiting factors and essential nutrients of microbial life. Since in nature it is not readily available in the preferred form, microorganisms produce small high affinity chelating molecules called siderophores for its acquisition. Microorganisms produce a wide variety of siderophores controlled at the molecular level by different genes to accumulate, mobilize and transport iron for metabolism. Siderophores also play a critical role in the expression of virulence and development of biofilms by different microbes. Apart from maintaining microbial life, siderophores can be harnessed for the sustainability of human, animals and plants. With the advent of modern molecular tools, a major breakthrough is taking place in the understanding of the multifaceted role of siderophores in nature. This mini review is intended to provide a general overview on siderophore along with its role and applications.
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Affiliation(s)
- Ratul Saha
- Department of Microbiology and Molecular Biology, NSF International, Ann Arbor, MI, USA.
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Sheldon JR, Heinrichs DE. The iron-regulated staphylococcal lipoproteins. Front Cell Infect Microbiol 2012; 2:41. [PMID: 22919632 PMCID: PMC3417571 DOI: 10.3389/fcimb.2012.00041] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2012] [Accepted: 03/13/2012] [Indexed: 01/01/2023] Open
Abstract
Lipoproteins fulfill diverse roles in antibiotic resistance, adhesion, protein secretion, signaling and sensing, and many also serve as the substrate binding protein (SBP) partner to ABC transporters for the acquisition of a diverse array of nutrients including peptides, sugars, and scarcely abundant metals. In the staphylococci, the iron-regulated SBPs are significantly upregulated during iron starvation and function to sequester and deliver iron into the bacterial cell, enabling staphylococci to circumvent iron restriction imposed by the host environment. Accordingly, this subset of lipoproteins has been implicated in staphylococcal pathogenesis and virulence. Lipoproteins also activate the host innate immune response, triggered through Toll-like receptor-2 (TLR2) and, notably, the iron-regulated subset of lipoproteins are particularly immunogenic. In this review, we discuss the iron-regulated staphylococcal lipoproteins with regard to their biogenesis, substrate specificity, and impact on the host innate immune response.
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Affiliation(s)
- Jessica R Sheldon
- Department of Microbiology and Immunology, Western University, London ON, Canada
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Gaupp R, Ledala N, Somerville GA. Staphylococcal response to oxidative stress. Front Cell Infect Microbiol 2012; 2:33. [PMID: 22919625 PMCID: PMC3417528 DOI: 10.3389/fcimb.2012.00033] [Citation(s) in RCA: 148] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2012] [Accepted: 02/29/2012] [Indexed: 12/23/2022] Open
Abstract
Staphylococci are a versatile genus of bacteria that are capable of causing acute and chronic infections in diverse host species. The success of staphylococci as pathogens is due in part to their ability to mitigate endogenous and exogenous oxidative and nitrosative stress. Endogenous oxidative stress is a consequence of life in an aerobic environment; whereas, exogenous oxidative and nitrosative stress are often due to the bacteria's interaction with host immune systems. To overcome the deleterious effects of oxidative and nitrosative stress, staphylococci have evolved protection, detoxification, and repair mechanisms that are controlled by a network of regulators. In this review, we summarize the cellular targets of oxidative stress, the mechanisms by which staphylococci sense oxidative stress and damage, oxidative stress protection and repair mechanisms, and regulation of the oxidative stress response. When possible, special attention is given to how the oxidative stress defense mechanisms help staphylococci control oxidative stress in the host.
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Affiliation(s)
- Rosmarie Gaupp
- School of Veterinary Medicine and Biomedical Sciences, University of Nebraska-Lincoln, Lincoln NE, USA
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DeDent A, Kim HK, Missiakas D, Schneewind O. Exploring Staphylococcus aureus pathways to disease for vaccine development. Semin Immunopathol 2012; 34:317-33. [PMID: 22130613 PMCID: PMC3539746 DOI: 10.1007/s00281-011-0299-z] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2011] [Accepted: 10/28/2011] [Indexed: 12/21/2022]
Abstract
Staphylococcus aureus is a commensal of the human skin or nares and a pathogen that frequently causes skin and soft tissue infections as well as bacteremia and sepsis. Recent efforts in understanding the molecular mechanisms of pathogenesis revealed key virulence strategies of S. aureus in host tissues: bacterial scavenging of iron, induction of coagulation pathways to promote staphylococcal agglutination in the vasculature, and suppression of innate and adaptive immune responses. Advances in all three areas have been explored for opportunities in vaccine design in an effort to identify the critical protective antigens of S. aureus. Human clinical trials with specific subunit vaccines have failed, yet provide important insights for the design of future trials that must address the current epidemic of S. aureus infections with drug-resistant isolates (MRSA, methicillin-resistant S. aureus).
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Affiliation(s)
- Andrea DeDent
- Department of Microbiology, University of Chicago, 920 East 58th Street, Chicago, IL 60637, USA
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Cassat JE, Skaar EP. Metal ion acquisition in Staphylococcus aureus: overcoming nutritional immunity. Semin Immunopathol 2012; 34:215-35. [PMID: 22048835 PMCID: PMC3796439 DOI: 10.1007/s00281-011-0294-4] [Citation(s) in RCA: 102] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2011] [Accepted: 10/14/2011] [Indexed: 12/19/2022]
Abstract
Transition metals are essential nutrients to virtually all forms of life, including bacterial pathogens. In Staphylococcus aureus, metal ions participate in diverse biochemical processes such as metabolism, DNA synthesis, regulation of virulence factors, and defense against oxidative stress. As an innate immune response to bacterial infection, vertebrate hosts sequester transition metals in a process that has been termed "nutritional immunity." To successfully infect vertebrates, S. aureus must overcome host sequestration of these critical nutrients. The objective of this review is to outline the current knowledge of staphylococcal metal ion acquisition systems, as well as to define the host mechanisms of nutritional immunity during staphylococcal infection.
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Affiliation(s)
- James E. Cassat
- Division of Pediatric Infectious Diseases, Department of Pediatrics, Vanderbilt University Medical Center, Nashville, TN 37232, USA
| | - Eric P. Skaar
- Department of Pathology, Microbiology, and Immunology, Vanderbilt University Medical Center, 1161 21st Ave South, A-5102 MCN, Nashville, TN 37232-2363, USA
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Expression of multidrug resistance efflux pump gene norA is iron responsive in Staphylococcus aureus. J Bacteriol 2012; 194:1753-62. [PMID: 22267518 DOI: 10.1128/jb.06582-11] [Citation(s) in RCA: 60] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
Staphylococcus aureus utilizes efflux transporter NorA to pump out a wide range of structurally dissimilar drugs, conferring low-level multidrug resistance. The regulation of norA expression has yet to be fully understood although past studies have revealed that this gene is under the control of the global transcriptional regulator MgrA and the two-component system ArlRS. To identify additional regulators of norA, we screened a transposon library in strain Newman expressing the transcriptional fusion norA-lacZ for altered β-galactosidase activity. We identify a transposon insertion in fhuB, a gene that encodes a ferric hydroxamate uptake system permease, and propose that the norA transcription is iron responsive. In agreement with this observation, addition of FeCl(3) repressed the induction of norA-lacZ, suggesting that bacterial iron uptake plays an important role in regulating norA transcription. In addition, a fur (ferric uptake regulator) deletion exhibited compromised norA transcription and reduced resistance to quinolone compared to the wild-type strain, indicating that fur functions as a positive regulator of norA. A putative Fur box identified in the promoter region of norA was confirmed by electrophoretic mobility shift and DNase I footprint assays. Finally, by employing a siderophore secretion assay, we reveal that NorA may contribute to the export of siderophores. Collectively, our experiments uncover some novel interactions between cellular iron level and norA regulation in S. aureus.
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38
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Troxell B, Fink RC, Porwollik S, McClelland M, Hassan HM. The Fur regulon in anaerobically grown Salmonella enterica sv. Typhimurium: identification of new Fur targets. BMC Microbiol 2011; 11:236. [PMID: 22017966 PMCID: PMC3212961 DOI: 10.1186/1471-2180-11-236] [Citation(s) in RCA: 60] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2011] [Accepted: 10/21/2011] [Indexed: 01/17/2023] Open
Abstract
Background The Ferric uptake regulator (Fur) is a transcriptional regulator that controls iron homeostasis in bacteria. Although the regulatory role of Fur in Escherichia coli is well characterized, most of the studies were conducted under routine culture conditions, i.e., in ambient oxygen concentration. To reveal potentially novel aspects of the Fur regulon in Salmonella enterica serovar Typhimurium under oxygen conditions similar to that encountered in the host, we compared the transcriptional profiles of the virulent wild-type strain (ATCC 14028s) and its isogenic Δfur strain under anaerobic conditions. Results Microarray analysis of anaerobically grown Δfur S. Typhimurium identified 298 differentially expressed genes. Expression of several genes controlled by Fnr and NsrR appeared to be also dependent on Fur. Furthermore, Fur was required for the activity of the cytoplasmic superoxide disumutases (MnSOD and FeSOD). The regulation of FeSOD gene, sodB, occurred via small RNAs (i.e., the ryhB homologs, rfrA and rfrB) with the aid of the RNA chaperone Hfq. The transcription of sodA was increased in Δfur; however, the enzyme was inactive due to the incorporation of iron instead of manganese in SodA. Additionally, in Δfur, the expression of the gene coding for the ferritin-like protein (ftnB) was down-regulated, while the transcription of the gene coding for the nitric oxide (NO·) detoxifying flavohemoglobin (hmpA) was up-regulated. The promoters of ftnB and hmpA do not contain recognized Fur binding motifs, which indicated their probable indirect regulation by Fur. However, Fur activation of ftnB was independent of Fnr. In addition, the expression of the gene coding for the histone-like protein, H-NS (hns) was increased in Δfur. This may explain the observed down-regulation of the tdc operon, responsible for the anaerobic degradation of threonine, and ftnB in Δfur. Conclusions This study determined that Fur is a positive factor in ftnB regulation, while serving to repress the expression of hmpA. Furthermore, Fur is required for the proper expression and activation of the antioxidant enzymes, FeSOD and MnSOD. Finally, this work identified twenty-six new targets of Fur regulation, and demonstrates that H-NS repressed genes are down-regulated in Δfur.
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Affiliation(s)
- Bryan Troxell
- Department of Microbiology, North Carolina State University, Raleigh, NC 27695-7615, USA
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39
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Expression of virulence factors by Staphylococcus aureus grown in serum. Appl Environ Microbiol 2011; 77:8097-105. [PMID: 21926198 DOI: 10.1128/aem.05316-11] [Citation(s) in RCA: 93] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Staphylococcus aureus produces many virulence factors, including toxins, immune-modulatory factors, and exoenzymes. Previous studies involving the analysis of virulence expression were mainly performed by in vitro experiments using bacterial medium. However, when S. aureus infects a host, the bacterial growth conditions are quite different from those in a medium, which may be related to the different expression of virulence factors in the host. In this study, we investigated the expression of virulence factors in S. aureus grown in calf serum. The expression of many virulence factors, including hemolysins, enterotoxins, proteases, and iron acquisition factors, was significantly increased compared with that in bacterial medium. In addition, the expression of RNA III, a global regulon for virulence expression, was significantly increased. This effect was partially restored by the addition of 300 μM FeCl₃ into serum, suggesting that iron depletion is associated with the increased expression of virulence factors in serum. In chemically defined medium without iron, a similar effect was observed. In a mutant with agr inactivated grown in serum, the expression of RNA III, psm, and sec4 was not increased, while other factors were still induced in the mutant, suggesting that another regulatory factor(s) is involved. In addition, we found that serum albumin is a major factor for the capture of free iron to prevent the supply of iron to bacteria grown in serum. These results indicate that S. aureus expresses virulence factors in adaptation to the host environment.
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Gao X, Wang LM, Bai YL, Jiang H, Li Y, Shi CH, Zhang H, Xue Y. Expression of Mycobacterium tuberculosis ferric uptake regulator A gene in Escherichia coli and generation of monoclonal antibodies to FurA. Hybridoma (Larchmt) 2011; 30:331-9. [PMID: 21851232 DOI: 10.1089/hyb.2011.0017] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Ferric uptake regulator A of Mycobacterium tuberculosis (MTB), which belongs to the Fur superfamily, is situated immediately upstream of katG encoding catalase-peroxidase, a major virulence factor that also activates the pro-drug isoniazid. The feature and role of FurA in oxidative stress contribute to research on the pathogenesis of mycobacteria. In this study, four novel mouse monoclonal antibodies were generated using the prokaryotically expressed FurA protein as immunogen. The furA gene of M. tuberculosis H37Rv was inserted into a bacterial expression vector of pRSET-A and effectively expressed in Escherichia coli BL21(DE3). The expressed fusion protein existed as soluble form in cell lysates and was purified via Ni-NTA purification system. Using the fusion protein to immunize BALB/c mice, four monoclonal antibodies (H9H6, H9E12, H10H6, and H10H8) were produced. As shown by Western blot analysis and cell fluorescence microscopy assay, the four antibodies could recognize the FurA protein, respectively. Then we assessed the effect of iron on the expression of FurA in MTB H37Rv and we concluded that iron does not affect FurA expression. These results suggest that the antibodies against FurA may provide a powerful tool for elucidating FurA biofunctions and regulation mechanism in the pathogenesis of tuberculosis.
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Affiliation(s)
- Xue Gao
- Department of Otorhinolaryngology, General Hospital of Second Artillery, Beijing, P.R. China
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41
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Nobles CL, Maresso AW. The theft of host heme by Gram-positive pathogenic bacteria. Metallomics 2011; 3:788-96. [PMID: 21725569 DOI: 10.1039/c1mt00047k] [Citation(s) in RCA: 56] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
The element iron is essential for bacteria and plays a key role in the virulence and pathology of bacterial diseases. The largest reservoir of iron within the human body is in protoporphyrin IX, the compound commonly referred to as heme and bound by hemoglobin. For many years, the study of heme uptake in bacteria was restricted to Gram-negative organisms. However, recent studies have shed light on how bacteria containing a thick peptidoglycan, such as Gram-positive bacteria, acquire and transport heme. This review summarizes old and new research covering the acquisition, transport, and utilization of heme in Gram-positive bacterial pathogens.
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Affiliation(s)
- Christopher L Nobles
- Molecular Virology and Microbiology, Baylor College of Medicine, One Baylor Plaza - BCM280, Houston, TX 77030, USA
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Identification of differential hepatic proteins in rare minnow (Gobiocypris rarus) exposed to pentachlorophenol (PCP) by proteomic analysis. Toxicol Lett 2010; 199:69-79. [PMID: 20732397 DOI: 10.1016/j.toxlet.2010.08.008] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2010] [Revised: 08/11/2010] [Accepted: 08/13/2010] [Indexed: 11/23/2022]
Abstract
Pentachlorophenol (PCP) is a ubiquitous contaminant that has been shown to lead to hepatoxicity and is implicated in the incidence of liver tumors in human. A number of previous studies have described the toxic effects of PCP based on conventional toxicological indices. However, little evidence on protein levels is available at present. For further understanding of mechanisms of action and identifying the potential protein biomarkers for PCP exposure, two-dimensional electrophoresis coupled with mass spectrometry has been used to identify proteins differentially expressed in the livers of rare minnow (Gobiocypris rarus) following PCP exposure of 0.5, 5, 50 μg/L. After comparison of the protein profiles from treated and control groups, 39 protein spots were found altered in abundance (>2-fold) from male and female PCP-treated groups. Matrix-assisted laser desorption/ionization (MALDI) tandem time-of-flight mass spectrometry (TOF/MS) analysis allowed the unambiguous identification, and 18 protein spots were identified successfully, 12 proteins in females and 6 proteins in males, respectively. These proteins were involved in transport, metabolism, response to oxidative stress and other biological processes. Of these proteins, four differentially expressed mRNA encoding proteins underwent quantitative analysis by quantitative real-time PCR (QRT-PCR). The consistent and discrepant results between mRNA and protein levels suggested that complicated regulatory mechanisms of gene expression were implicated in the response to PCP exposure. In addition, marked gender differences in response to PCP have been described from the comparison of the male and female liver protein profiles.
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Johnson M, Sengupta M, Purves J, Tarrant E, Williams PH, Cockayne A, Muthaiyan A, Stephenson R, Ledala N, Wilkinson BJ, Jayaswal RK, Morrissey JA. Fur is required for the activation of virulence gene expression through the induction of the sae regulatory system in Staphylococcus aureus. Int J Med Microbiol 2010; 301:44-52. [PMID: 20705504 DOI: 10.1016/j.ijmm.2010.05.003] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2009] [Revised: 02/26/2010] [Accepted: 05/09/2010] [Indexed: 01/05/2023] Open
Abstract
Our previous studies showed that both Sae and Fur are required for the induction of eap and emp expression in low iron. In this study, we show that expression of sae is also iron-regulated, as sae expression is activated by Fur in low iron. We also demonstrate that both Fur and Sae are required for full induction of the oxidative stress response and expression of non-covalently bound surface proteins in low-iron growth conditions. In addition, Sae is required for the induced expression of the important virulence factors isdA and isdB in low iron. Our studies also indicate that Fur is required for the induced expression of the global regulators Agr and Rot in low iron and a number of extracellular virulence factors such as the haemolysins which are also Sae- and Agr-regulated. Hence, we show that Fur is central to a complex regulatory network that is required for the induced expression of a number of important S. aureus virulence determinants in low iron.
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Affiliation(s)
- Miranda Johnson
- Dept. of Genetics, University of Leicester, University Road, Leicester LE1 7RH, UK
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Staphylococcus aureus fur regulates the expression of virulence factors that contribute to the pathogenesis of pneumonia. Infect Immun 2010; 78:1618-28. [PMID: 20100857 DOI: 10.1128/iai.01423-09] [Citation(s) in RCA: 115] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The tremendous success of Staphylococcus aureus as a pathogen is due to the controlled expression of a diverse array of virulence factors. The effects of host environments on the expression of virulence factors and the mechanisms by which S. aureus adapts to colonize distinct host tissues are largely unknown. Vertebrates have evolved to sequester nutrient iron from invading bacteria, and iron availability is a signal that alerts pathogenic microorganisms when they enter the hostile host environment. Consistent with this, we report here that S. aureus senses alterations in the iron status via the ferric uptake regulator (Fur) and alters the abundance of a large number of virulence factors. These Fur-mediated changes protect S. aureus against killing by neutrophils, and Fur is required for full staphylococcal virulence in a murine model of infection. A potential mechanistic explanation for the impact of Fur on virulence is provided by the observation that Fur coordinates the reciprocal expression of cytolysins and a subset of immunomodulatory proteins. More specifically, S. aureus lacking fur exhibits decreased expression of immunomodulatory proteins and increased expression of cytolysins. These findings reveal that Fur is involved in initiating a regulatory program that organizes the expression of virulence factors during the pathogenesis of S. aureus pneumonia.
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This is not your mother's repressor: the complex role of fur in pathogenesis. Infect Immun 2009; 77:2590-601. [PMID: 19364842 DOI: 10.1128/iai.00116-09] [Citation(s) in RCA: 166] [Impact Index Per Article: 11.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
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Raza W, Wu H, Shah MAA, Shen Q. Retracted: A catechol type siderophore, bacillibactin: biosynthesis, regulation and transport in Bacillus subtilis. J Basic Microbiol 2008; 48. [PMID: 18785660 DOI: 10.1002/jobm.200800097] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Retraction: The following article from the Journal of Basic Microbiology, "A catechol type siderophore, bacillibactin: biosynthesis, regulation and transport in Bacillus subtilis" by Waseem Raza, Hongsheng Wu, Muhammad Ali Abdullah Shah and Qirong Shen, published online on 11 September 2008 in Wiley InterScience (www.interscience.wiley.com), has been retracted by agreement between the authors, the journal Editor-in-Chief, Erika Kothe, and the publisher Wiley-VCH. The retraction has been agreed due to substantial overlap of the content of this article with previously published articles in other journals.The Journal of Basic Microbiology apologises to our readership.
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Affiliation(s)
- Waseem Raza
- College of Resource and Environmental Sciences, Nanjing Agriculture University, Nanjing, China
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Sitthisak S, Knutsson L, Webb JW, Jayaswal RK. Molecular characterization of the copper transport system in Staphylococcus aureus. MICROBIOLOGY-SGM 2008; 153:4274-4283. [PMID: 18048940 DOI: 10.1099/mic.0.2007/009860-0] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
The Staphylococcus aureus copA gene codes for a putative copper-translocating P-type ATPase and the downstream copZ gene codes for a copper chaperone. Genome database analyses demonstrate that these copper transport genes are highly conserved in S. aureus. The expression of copA and copZ was inducible by copper and to some extent by ferric and lead ions. A mutant strain containing a partially deleted copA gene was more sensitive than the parent strain to copper, ferric and lead ions. The copper-sensitive phenotype was due to the accumulation of intracellular copper and thus the copA product is involved in the export of copper ions. The metal-sensitive phenotype of the mutant was complemented in trans by a 2.7 kbp DNA containing copA. We have cloned and overexpressed the metal-binding domains of CopA and CopZ and have shown by site-directed mutagenesis that the cysteine residues in the CXXC metal-binding motif in CopA are involved in copper binding and thus play an important role in copper transport in S. aureus.
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Affiliation(s)
- Sutthirat Sitthisak
- Department of Biological Sciences, Illinois State University, Normal, IL 61790, USA
| | - Lawrence Knutsson
- Department of Biological Sciences, Illinois State University, Normal, IL 61790, USA
| | - James W Webb
- Department of Chemistry, Illinois State University, Normal, IL 61790, USA
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Iron-regulated biofilm formation in Staphylococcus aureus Newman requires ica and the secreted protein Emp. Infect Immun 2008; 76:1756-65. [PMID: 18268030 DOI: 10.1128/iai.01635-07] [Citation(s) in RCA: 81] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023] Open
Abstract
Staphylococcus aureus biofilm formation is induced in iron-restricted growth conditions in vitro. In this study, we showed that Emp and Eap play important roles in low-iron-induced biofilm formation of S. aureus Newman. Eap and Emp are secreted proteins which are non-covalently attached to the S. aureus cell surface and have previously been implicated in a number of aspects of S. aureus pathogenesis. We showed here that the transcription of these important virulence factors is induced by growth in low-iron medium, reflective of the in vivo environment. Our results show that iron regulation of Eap and Emp is Fur independent. However, Fur is required for full induction of eap and emp expression in low-iron conditions. In this study, we demonstrated that in addition to Fur, low-iron-induced biofilm formation requires Sae, Agr, and SarA. In iron-restricted growth conditions, Sae and Agr are essential for Emp and Eap expression and hence for biofilm formation, whereas SarA appears to have a less-significant role. We also showed that expression of the ica operon is required for biofilm formation in iron-restricted growth conditions. We demonstrated that in fact, ica is required for the expression of the important multifunctional virulence determinants eap and emp.
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Friedman DB, Stauff DL, Pishchany G, Whitwell CW, Torres VJ, Skaar EP. Staphylococcus aureus redirects central metabolism to increase iron availability. PLoS Pathog 2006; 2:e87. [PMID: 16933993 PMCID: PMC1557832 DOI: 10.1371/journal.ppat.0020087] [Citation(s) in RCA: 157] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2006] [Accepted: 07/14/2006] [Indexed: 12/01/2022] Open
Abstract
Staphylococcus aureus pathogenesis is significantly influenced by the iron status of the host. However, the regulatory impact of host iron sources on S. aureus gene expression remains unknown. In this study, we combine multivariable difference gel electrophoresis and mass spectrometry with multivariate statistical analyses to systematically cluster cellular protein response across distinct iron-exposure conditions. Quadruplicate samples were simultaneously analyzed for alterations in protein abundance and/or post-translational modification state in response to environmental (iron chelation, hemin treatment) or genetic (Δfur) alterations in bacterial iron exposure. We identified 120 proteins representing several coordinated biochemical pathways that are affected by changes in iron-exposure status. Highlighted in these experiments is the identification of the heme-regulated transport system (HrtAB), a novel transport system which plays a critical role in staphylococcal heme metabolism. Further, we show that regulated overproduction of acidic end-products brought on by iron starvation decreases local pH resulting in the release of iron from the host iron-sequestering protein transferrin. These findings reveal novel strategies used by S. aureus to acquire scarce nutrients in the hostile host environment and begin to define the iron and heme-dependent regulons of S. aureus. Virtually all bacterial pathogens require iron to successfully infect their human hosts. This presents a problem to invading bacteria because the majority of iron in humans is tightly bound by iron-binding proteins. To counteract this host defense, bacterial pathogens have developed elaborate mechanisms to acquire nutrient iron during infection. To gain insight into how the amount of available iron impacts the human pathogen Staphylococcus aureus, the authors identified proteins that increase or decrease abundance upon alterations in iron status. The authors found that under conditions of iron starvation, the Fur regulatory protein of S. aureus coordinates a redirection of the central metabolic pathways causing the bacteria to produce large amounts of acidic end-products. The accumulation of these acidic end-products facilitates the release of iron from host iron-binding proteins, in effect increasing the availability of this precious nutrient source. These findings provide a mechanistic explanation for how S. aureus alters its local microenvironment during infection to increase the availability of nutrient iron. Based on the well-established role for bacterial iron acquisition during pathogenesis, systems involved in iron acquisition represent excellent potential therapeutic targets against bacterial infection.
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Affiliation(s)
- David B Friedman
- Mass Spectrometry Research Center, Department of Biochemistry, Vanderbilt University Medical Center, Nashville, Tennessee, United States of America
| | - Devin L Stauff
- Department of Microbiology and Immunology, Vanderbilt University Medical Center, Nashville, Tennessee, United States of America
| | - Gleb Pishchany
- Department of Microbiology and Immunology, Vanderbilt University Medical Center, Nashville, Tennessee, United States of America
| | - Corbin W Whitwell
- Mass Spectrometry Research Center, Department of Biochemistry, Vanderbilt University Medical Center, Nashville, Tennessee, United States of America
| | - Victor J Torres
- Department of Microbiology and Immunology, Vanderbilt University Medical Center, Nashville, Tennessee, United States of America
| | - Eric P Skaar
- Department of Microbiology and Immunology, Vanderbilt University Medical Center, Nashville, Tennessee, United States of America
- * To whom correspondence should be addressed. E-mail:
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Cosgrove K, Coutts G, Jonsson IM, Tarkowski A, Kokai-Kun JF, Mond JJ, Foster SJ. Catalase (KatA) and alkyl hydroperoxide reductase (AhpC) have compensatory roles in peroxide stress resistance and are required for survival, persistence, and nasal colonization in Staphylococcus aureus. J Bacteriol 2006; 189:1025-35. [PMID: 17114262 PMCID: PMC1797328 DOI: 10.1128/jb.01524-06] [Citation(s) in RCA: 228] [Impact Index Per Article: 12.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Oxidative-stress resistance in Staphylococcus aureus is linked to metal ion homeostasis via several interacting regulators. In particular, PerR controls the expression of a regulon of genes, many of which encode antioxidants. Two PerR regulon members, ahpC (alkylhydroperoxide reductase) and katA (catalase), show compensatory regulation, with independent and linked functions. An ahpC mutation leads to increased H2O2 resistance due to greater katA expression via relief of PerR repression. Moreover, AhpC provides residual catalase activity present in a katA mutant. Mutation of both katA and ahpC leads to a severe growth defect under aerobic conditions in defined media (attributable to lack of catalase activity). This results in the inability to scavenge exogenous or endogenously produced H2O2, resulting in accumulation of H2O2 in the medium. This leads to DNA damage, the likely cause of the growth defect. Surprisingly, the katA ahpC mutant is not attenuated in two independent models of infection, which implies reduced oxygen availability during infection. In contrast, both AhpC and KatA are required for environmental persistence (desiccation) and nasal colonization. Thus, oxidative-stress resistance is an important factor in the ability of S. aureus to persist in the hospital environment and so contribute to the spread of human disease.
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Affiliation(s)
- Kate Cosgrove
- Department of Molecular Biology and Biotechnology, University of Sheffield, Western Bank, Sheffield, S10 2TN, United Kingdom
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