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Agnew HN, Atack JM, Fernando AR, Waters SN, van der Linden M, Smith E, Abell AD, Brazel EB, Paton JC, Trappetti C. Uncovering the link between the SpnIII restriction modification system and LuxS in Streptococcus pneumoniae meningitis isolates. Front Cell Infect Microbiol 2023; 13:1177857. [PMID: 37197203 PMCID: PMC10184825 DOI: 10.3389/fcimb.2023.1177857] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2023] [Accepted: 04/17/2023] [Indexed: 05/19/2023] Open
Abstract
Streptococcus pneumoniae is capable of randomly switching their genomic DNA methylation pattern between six distinct bacterial subpopulations (A-F) via recombination of a type 1 restriction-modification locus, spnIII. These pneumococcal subpopulations exhibit phenotypic changes which favor carriage or invasive disease. In particular, the spnIIIB allele has been associated with increased nasopharyngeal carriage and the downregulation of the luxS gene. The LuxS/AI-2 QS system represent a universal language for bacteria and has been linked to virulence and biofilm formation in S. pneumoniae. In this work, we have explored the link between spnIII alleles, the luxS gene and virulence in two clinical pneumococcal isolates from the blood and cerebrospinal fluid (CSF) of one pediatric meningitis patient. The blood and CSF strains showed different virulence profiles in mice. Analysis of the spnIII system of these strains recovered from the murine nasopharynx showed that the system switched to different alleles commensurate with the initial source of the isolate. Of note, the blood strain showed high expression of spnIIIB allele, previously linked with less LuxS protein production. Importantly, strains with deleted luxS displayed different phenotypic profiles compared to the wildtype, but similar to the strains recovered from the nasopharynx of infected mice. This study used clinically relevant S. pneumoniae strains to demonstrate that the regulatory network between luxS and the type 1 restriction-modification system play a key role in infections and may support different adaptation to specific host niches.
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Affiliation(s)
- Hannah N. Agnew
- Research Centre for Infectious Diseases, Department of Molecular and Biomedical Science, University of Adelaide, Adelaide, SA, Australia
| | - John M. Atack
- Institute for Glycomics, Griffith University, Gold Coast, QLD, Australia
- School of Environment and Science, Griffith University, Gold Coast, QLD, Australia
| | - Ann R.D. Fernando
- Research Centre for Infectious Diseases, Department of Molecular and Biomedical Science, University of Adelaide, Adelaide, SA, Australia
| | - Sophie N. Waters
- Research Centre for Infectious Diseases, Department of Molecular and Biomedical Science, University of Adelaide, Adelaide, SA, Australia
| | - Mark van der Linden
- German National Reference Center for Streptococci, University Hospital Rheinisch-Westfälische Technische Hochschule (RWTH) Aachen, Aachen, Germany
| | - Erin Smith
- School of Physical Sciences, Faculty of Sciences, Engineering and Technology, University of Adelaide, Adelaide, SA, Australia
| | - Andrew D. Abell
- School of Physical Sciences, Faculty of Sciences, Engineering and Technology, University of Adelaide, Adelaide, SA, Australia
| | - Erin B. Brazel
- Research Centre for Infectious Diseases, Department of Molecular and Biomedical Science, University of Adelaide, Adelaide, SA, Australia
| | - James C. Paton
- Research Centre for Infectious Diseases, Department of Molecular and Biomedical Science, University of Adelaide, Adelaide, SA, Australia
- *Correspondence: Claudia Trappetti, ; James C. Paton,
| | - Claudia Trappetti
- Research Centre for Infectious Diseases, Department of Molecular and Biomedical Science, University of Adelaide, Adelaide, SA, Australia
- *Correspondence: Claudia Trappetti, ; James C. Paton,
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Agnew HN, Brazel EB, Tikhomirova A, van der Linden M, McLean KT, Paton JC, Trappetti C. Streptococcus pneumoniae Strains Isolated From a Single Pediatric Patient Display Distinct Phenotypes. Front Cell Infect Microbiol 2022; 12:866259. [PMID: 35433506 PMCID: PMC9008571 DOI: 10.3389/fcimb.2022.866259] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2022] [Accepted: 03/08/2022] [Indexed: 11/13/2022] Open
Abstract
Streptococcus pneumoniae is the leading cause of bacterial paediatric meningitis after the neonatal period worldwide, but the bacterial factors and pathophysiology that drive pneumococcal meningitis are not fully understood. In this work, we have identified differences in raffinose utilization by S. pneumoniae isolates of identical serotype and sequence type from the blood and cerebrospinal fluid (CSF) of a single pediatric patient with meningitis. The blood isolate displayed defective raffinose metabolism, reduced transcription of the raffinose utilization pathway genes, and an inability to grow in vitro when raffinose was the sole carbon source. The fitness of these strains was then assessed using a murine intranasal infection model. Compared with the CSF isolate, mice infected with the blood isolate displayed higher bacterial numbers in the nose, but this strain was unable to invade the ears of infected mice. A premature stop codon was identified in the aga gene in the raffinose locus, suggesting that this protein likely displays impaired alpha-galactosidase activity. These closely related strains were assessed by Illumina sequencing, which did not identify any single nucleotide polymorphisms (SNPs) between the two strains. However, these wider genomic analyses identified the presence of an alternative alpha-galactosidase gene that appeared to display altered sequence coverage between the strains, which may account for the observed differences in raffinose metabolic capacity. Together, these studies support previous findings that raffinose utilization capacity contributes to disease progression, and provide insight into a possible alternative means by which perturbation of this pathway may influence the behavior of pneumococci in the host environment, particularly in meningitis.
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Affiliation(s)
- Hannah N. Agnew
- Research Centre for Infectious Diseases, Department of Molecular and Biomedical Science, The University of Adelaide, Adelaide, SAAustralia
| | - Erin B. Brazel
- Research Centre for Infectious Diseases, Department of Molecular and Biomedical Science, The University of Adelaide, Adelaide, SAAustralia
| | - Alexandra Tikhomirova
- Research Centre for Infectious Diseases, Department of Molecular and Biomedical Science, The University of Adelaide, Adelaide, SAAustralia
| | - Mark van der Linden
- German National Reference Center for Streptoccocci, University Hospital Rheinisch-Westfälische Technische Hochschule (RWTH) Aachen, Aachen, Germany
| | - Kimberley T. McLean
- Research Centre for Infectious Diseases, Department of Molecular and Biomedical Science, The University of Adelaide, Adelaide, SAAustralia
| | - James C. Paton
- Research Centre for Infectious Diseases, Department of Molecular and Biomedical Science, The University of Adelaide, Adelaide, SAAustralia
- *Correspondence: Claudia Trappetti, ; James C. Paton,
| | - Claudia Trappetti
- Research Centre for Infectious Diseases, Department of Molecular and Biomedical Science, The University of Adelaide, Adelaide, SAAustralia
- *Correspondence: Claudia Trappetti, ; James C. Paton,
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Adams FG, Pokhrel A, Brazel EB, Semenec L, Li L, Trappetti C, Paton JC, Cain AK, Paulsen IT, Eijkelkamp BA. Acinetobacter baumannii Fatty Acid Desaturases Facilitate Survival in Distinct Environments. ACS Infect Dis 2021; 7:2221-2228. [PMID: 34100578 DOI: 10.1021/acsinfecdis.1c00192] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Maintaining optimal fluidity is essential to ensure adequate membrane structure and function under different environmental conditions. We apply integrated molecular approaches to characterize two desaturases (DesA and DesB) and define their specific roles in unsaturated fatty acid (UFA) production in Acinetobacter baumannii. Using a murine model, we reveal DesA to play a minor role in colonization of the respiratory tract, whereas DesB is important during invasive disease. Furthermore, using transcriptomic and bioinformatic analyses, a global regulator involved in fatty acid homeostasis and members of its regulon are characterized. Collectively, we show that DesA and DesB are primary contributors to UFA production in A. baumannii with infection studies illustrating that these distinct desaturases aid in the bacterium's ability to survive in multiple host niches. Hence, this study provides novel insights into the fundamentals of A. baumannii lipid biology, which contributes to the versatility of this critical bacterial pathogen.
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Affiliation(s)
- Felise G. Adams
- Molecular Sciences and Technology, College of Science and Engineering, Flinders University, Bedford Park, South Australia 5042, Australia
| | - Alaska Pokhrel
- Department of Molecular Sciences, Macquarie University, Sydney, New South Wales 2109, Australia
| | - Erin B. Brazel
- Research Centre for Infectious Diseases, Department of Molecular and Biomedical Science, University of Adelaide, Adelaide, South Australia 5005, Australia
| | - Lucie Semenec
- Department of Molecular Sciences, Macquarie University, Sydney, New South Wales 2109, Australia
| | - Liping Li
- Department of Molecular Sciences, Macquarie University, Sydney, New South Wales 2109, Australia
| | - Claudia Trappetti
- Research Centre for Infectious Diseases, Department of Molecular and Biomedical Science, University of Adelaide, Adelaide, South Australia 5005, Australia
| | - James C. Paton
- Research Centre for Infectious Diseases, Department of Molecular and Biomedical Science, University of Adelaide, Adelaide, South Australia 5005, Australia
| | - Amy K. Cain
- Department of Molecular Sciences, Macquarie University, Sydney, New South Wales 2109, Australia
| | - Ian T. Paulsen
- Department of Molecular Sciences, Macquarie University, Sydney, New South Wales 2109, Australia
| | - Bart A. Eijkelkamp
- Molecular Sciences and Technology, College of Science and Engineering, Flinders University, Bedford Park, South Australia 5042, Australia
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Eijkelkamp BA, Morey JR, Neville SL, Tan A, Pederick VG, Cole N, Singh PP, Ong CLY, Gonzalez de Vega R, Clases D, Cunningham BA, Hughes CE, Comerford I, Brazel EB, Whittall JJ, Plumptre CD, McColl SR, Paton JC, McEwan AG, Doble PA, McDevitt CA. Dietary zinc and the control of Streptococcus pneumoniae infection. PLoS Pathog 2019; 15:e1007957. [PMID: 31437249 PMCID: PMC6705770 DOI: 10.1371/journal.ppat.1007957] [Citation(s) in RCA: 42] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2018] [Accepted: 07/03/2019] [Indexed: 12/21/2022] Open
Abstract
Human zinc deficiency increases susceptibility to bacterial infection. Although zinc supplementation therapies can reduce the impact of disease, the molecular basis for protection remains unclear. Streptococcus pneumoniae is a major cause of bacterial pneumonia, which is prevalent in regions of zinc deficiency. We report that dietary zinc levels dictate the outcome of S. pneumoniae infection in a murine model. Dietary zinc restriction impacts murine tissue zinc levels with distribution post-infection altered, and S. pneumoniae virulence and infection enhanced. Although the activation and infiltration of murine phagocytic cells was not affected by zinc restriction, their efficacy of bacterial control was compromised. S. pneumoniae was shown to be highly sensitive to zinc intoxication, with this process impaired in zinc restricted mice and isolated phagocytic cells. Collectively, these data show how dietary zinc deficiency increases sensitivity to S. pneumoniae infection while revealing a role for zinc as a component of host antimicrobial defences. Zinc deficiency affects one-third of the world’s population and is associated with an increased susceptibility to bacterial infection. Despite this, the molecular basis for how zinc deficiency compromises host control of infection remains to be understood. We show that dietary zinc deficiency impacts host tissue zinc abundances and its mobilization during infection by the major respiratory pathogen Streptococcus pneumoniae. Zinc acts as a direct antimicrobial against the pathogen, mobilized by phagocytic cells as a component of the innate immune response. Although immune activation and infiltration of phagocytic cells is unaffected by host zinc status, the lack of antimicrobial zinc compromises bacterial control in zinc deficient hosts. These findings highlight the importance of zinc sufficiency in resisting bacterial infection.
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Affiliation(s)
- Bart A Eijkelkamp
- Research Centre for Infectious Diseases, Department of Molecular and Biomedical Science, School of Biological Sciences, The University of Adelaide, Adelaide, Australia
| | - Jacqueline R Morey
- Department of Molecular and Biomedical Science, School of Biological Sciences, The University of Adelaide, Adelaide, Australia
| | - Stephanie L Neville
- Department of Molecular and Biomedical Science, School of Biological Sciences, The University of Adelaide, Adelaide, Australia.,Department of Microbiology and Immunology, The Peter Doherty Institute for Infection and Immunity, University of Melbourne, Melbourne, Victoria, Australia
| | - Aimee Tan
- Department of Microbiology and Immunology, The Peter Doherty Institute for Infection and Immunity, University of Melbourne, Melbourne, Victoria, Australia
| | - Victoria G Pederick
- Department of Molecular and Biomedical Science, School of Biological Sciences, The University of Adelaide, Adelaide, Australia
| | - Nerida Cole
- The Atomic Medicine Initiative, University of Technology, Broadway, Sydney, New South Wales, Australia.,ARC Training Centre in Biodevices, Faculty of Science, Engineering and Technology, Swinburne University of Technology, Hawthorn, Victoria, Australia
| | - Prashina P Singh
- The Atomic Medicine Initiative, University of Technology, Broadway, Sydney, New South Wales, Australia
| | - Cheryl-Lynn Y Ong
- Australian Infectious Diseases Research Centre, School of Chemistry and Molecular Biosciences, University of Queensland, Brisbane, Queensland, Australia
| | - Raquel Gonzalez de Vega
- The Atomic Medicine Initiative, University of Technology, Broadway, Sydney, New South Wales, Australia
| | - David Clases
- The Atomic Medicine Initiative, University of Technology, Broadway, Sydney, New South Wales, Australia
| | - Bliss A Cunningham
- Department of Microbiology and Immunology, The Peter Doherty Institute for Infection and Immunity, University of Melbourne, Melbourne, Victoria, Australia
| | - Catherine E Hughes
- Research Centre for Infectious Diseases, Department of Molecular and Biomedical Science, School of Biological Sciences, The University of Adelaide, Adelaide, Australia
| | - Iain Comerford
- Department of Molecular and Biomedical Science, School of Biological Sciences, The University of Adelaide, Adelaide, Australia
| | - Erin B Brazel
- Research Centre for Infectious Diseases, Department of Molecular and Biomedical Science, School of Biological Sciences, The University of Adelaide, Adelaide, Australia
| | - Jonathan J Whittall
- Department of Molecular and Biomedical Science, School of Biological Sciences, The University of Adelaide, Adelaide, Australia
| | - Charles D Plumptre
- Research Centre for Infectious Diseases, Department of Molecular and Biomedical Science, School of Biological Sciences, The University of Adelaide, Adelaide, Australia
| | - Shaun R McColl
- Department of Molecular and Biomedical Science, School of Biological Sciences, The University of Adelaide, Adelaide, Australia
| | - James C Paton
- Research Centre for Infectious Diseases, Department of Molecular and Biomedical Science, School of Biological Sciences, The University of Adelaide, Adelaide, Australia
| | - Alastair G McEwan
- Australian Infectious Diseases Research Centre, School of Chemistry and Molecular Biosciences, University of Queensland, Brisbane, Queensland, Australia
| | - Philip A Doble
- The Atomic Medicine Initiative, University of Technology, Broadway, Sydney, New South Wales, Australia
| | - Christopher A McDevitt
- Department of Molecular and Biomedical Science, School of Biological Sciences, The University of Adelaide, Adelaide, Australia.,Department of Microbiology and Immunology, The Peter Doherty Institute for Infection and Immunity, University of Melbourne, Melbourne, Victoria, Australia
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Bohlmann L, De Oliveira DMP, El-Deeb IM, Brazel EB, Harbison-Price N, Ong CLY, Rivera-Hernandez T, Ferguson SA, Cork AJ, Phan MD, Soderholm AT, Davies MR, Nimmo GR, Dougan G, Schembri MA, Cook GM, McEwan AG, von Itzstein M, McDevitt CA, Walker MJ. Chemical Synergy between Ionophore PBT2 and Zinc Reverses Antibiotic Resistance. mBio 2018; 9:e02391-18. [PMID: 30538186 PMCID: PMC6299484 DOI: 10.1128/mbio.02391-18] [Citation(s) in RCA: 39] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2018] [Accepted: 11/05/2018] [Indexed: 11/20/2022] Open
Abstract
The World Health Organization reports that antibiotic-resistant pathogens represent an imminent global health disaster for the 21st century. Gram-positive superbugs threaten to breach last-line antibiotic treatment, and the pharmaceutical industry antibiotic development pipeline is waning. Here we report the synergy between ionophore-induced physiological stress in Gram-positive bacteria and antibiotic treatment. PBT2 is a safe-for-human-use zinc ionophore that has progressed to phase 2 clinical trials for Alzheimer's and Huntington's disease treatment. In combination with zinc, PBT2 exhibits antibacterial activity and disrupts cellular homeostasis in erythromycin-resistant group A Streptococcus (GAS), methicillin-resistant Staphylococcus aureus (MRSA), and vancomycin-resistant Enterococcus (VRE). We were unable to select for mutants resistant to PBT2-zinc treatment. While ineffective alone against resistant bacteria, several clinically relevant antibiotics act synergistically with PBT2-zinc to enhance killing of these Gram-positive pathogens. These data represent a new paradigm whereby disruption of bacterial metal homeostasis reverses antibiotic-resistant phenotypes in a number of priority human bacterial pathogens.IMPORTANCE The rise of bacterial antibiotic resistance coupled with a reduction in new antibiotic development has placed significant burdens on global health care. Resistant bacterial pathogens such as methicillin-resistant Staphylococcus aureus and vancomycin-resistant Enterococcus are leading causes of community- and hospital-acquired infection and present a significant clinical challenge. These pathogens have acquired resistance to broad classes of antimicrobials. Furthermore, Streptococcus pyogenes, a significant disease agent among Indigenous Australians, has now acquired resistance to several antibiotic classes. With a rise in antibiotic resistance and reduction in new antibiotic discovery, it is imperative to investigate alternative therapeutic regimens that complement the use of current antibiotic treatment strategies. As stated by the WHO Director-General, "On current trends, common diseases may become untreatable. Doctors facing patients will have to say, Sorry, there is nothing I can do for you."
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Affiliation(s)
- Lisa Bohlmann
- School of Chemistry and Molecular Biosciences and Australian Infectious Diseases Research Centre, The University of Queensland, Brisbane, QLD, Australia
| | - David M P De Oliveira
- School of Chemistry and Molecular Biosciences and Australian Infectious Diseases Research Centre, The University of Queensland, Brisbane, QLD, Australia
| | - Ibrahim M El-Deeb
- Institute for Glycomics, Griffith University, Brisbane, QLD, Australia
| | - Erin B Brazel
- Research Centre for Infectious Diseases, School of Biological Sciences, University of Adelaide, Adelaide, SA, Australia
| | | | - Cheryl-Lynn Y Ong
- School of Chemistry and Molecular Biosciences and Australian Infectious Diseases Research Centre, The University of Queensland, Brisbane, QLD, Australia
| | - Tania Rivera-Hernandez
- School of Chemistry and Molecular Biosciences and Australian Infectious Diseases Research Centre, The University of Queensland, Brisbane, QLD, Australia
| | - Scott A Ferguson
- Department of Microbiology and Immunology, University of Otago, Dunedin, New Zealand
| | - Amanda J Cork
- School of Chemistry and Molecular Biosciences and Australian Infectious Diseases Research Centre, The University of Queensland, Brisbane, QLD, Australia
| | - Minh-Duy Phan
- School of Chemistry and Molecular Biosciences and Australian Infectious Diseases Research Centre, The University of Queensland, Brisbane, QLD, Australia
| | - Amelia T Soderholm
- School of Chemistry and Molecular Biosciences and Australian Infectious Diseases Research Centre, The University of Queensland, Brisbane, QLD, Australia
| | - Mark R Davies
- Department of Microbiology and Immunology at the Peter Doherty Institute for Infection and Immunity, The University of Melbourne, Melbourne, VIC, Australia
| | - Graeme R Nimmo
- Pathology Queensland Central Laboratory, Brisbane, QLD, Australia
| | - Gordon Dougan
- Wellcome Trust Sanger Institute, Hinxton, United Kingdom
| | - Mark A Schembri
- School of Chemistry and Molecular Biosciences and Australian Infectious Diseases Research Centre, The University of Queensland, Brisbane, QLD, Australia
| | - Gregory M Cook
- Department of Microbiology and Immunology, University of Otago, Dunedin, New Zealand
| | - Alastair G McEwan
- School of Chemistry and Molecular Biosciences and Australian Infectious Diseases Research Centre, The University of Queensland, Brisbane, QLD, Australia
| | - Mark von Itzstein
- Institute for Glycomics, Griffith University, Brisbane, QLD, Australia
| | - Christopher A McDevitt
- Research Centre for Infectious Diseases, School of Biological Sciences, University of Adelaide, Adelaide, SA, Australia
| | - Mark J Walker
- School of Chemistry and Molecular Biosciences and Australian Infectious Diseases Research Centre, The University of Queensland, Brisbane, QLD, Australia
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Grim KP, San Francisco B, Radin JN, Brazel EB, Kelliher JL, Párraga Solórzano PK, Kim PC, McDevitt CA, Kehl-Fie TE. The Metallophore Staphylopine Enables Staphylococcus aureus To Compete with the Host for Zinc and Overcome Nutritional Immunity. mBio 2017; 8:e01281-17. [PMID: 29089427 PMCID: PMC5666155 DOI: 10.1128/mbio.01281-17] [Citation(s) in RCA: 88] [Impact Index Per Article: 12.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2017] [Accepted: 09/27/2017] [Indexed: 12/18/2022] Open
Abstract
During infection, the host sequesters essential nutrients, such as zinc, to combat invading microbes. Despite the ability of the immune effector protein calprotectin to bind zinc with subpicomolar affinity, Staphylococcus aureus is able to successfully compete with the host for zinc. However, the zinc importers expressed by S. aureus remain unknown. Our investigations have revealed that S. aureus possesses two importers, AdcABC and CntABCDF, which are induced in response to zinc limitation. While AdcABC is similar to known zinc importers in other bacteria, CntABCDF has not previously been associated with zinc acquisition. Concurrent loss of the two systems severely impairs the ability of S. aureus to obtain zinc and grow in zinc-limited environments. Further investigations revealed that the Cnt system is responsible for the ability of S. aureus to compete with calprotectin for zinc in culture and contributes to acquisition of zinc during infection. The cnt locus also enables S. aureus to produce the broad-spectrum metallophore staphylopine. Similarly to the Cnt transporter, loss of staphylopine severely impairs the ability of S. aureus to resist host-imposed zinc starvation, both in culture and during infection. Further investigations revealed that together staphylopine and the Cnt importer function analogously to siderophore-based iron acquisition systems in order to facilitate zinc acquisition by S. aureus Analogous systems are found in a broad range of Gram-positive and Gram-negative bacterial pathogens, suggesting that this new type of zinc importer broadly contributes to the ability of bacteria to cause infection.IMPORTANCE A critical host defense against infection is the restriction of zinc availability. Despite the subpicomolar affinity of the immune effector calprotectin for zinc, Staphylococcus aureus can successfully compete for this essential metal. Here, we describe two zinc importers, AdcABC and CntABCDF, possessed by S. aureus, the latter of which has not previously been associated with zinc acquisition. The ability of S. aureus to compete with the host for zinc is dependent on CntABCDF and the metallophore staphylopine, both in culture and during infection. These results expand the mechanisms utilized by bacteria to obtain zinc, beyond Adc-like systems, and demonstrate that pathogens utilize strategies similar to siderophore-based iron acquisition to obtain other essential metals during infection. The staphylopine synthesis machinery is present in a diverse collection of bacteria, suggesting that this new family of zinc importers broadly contributes to the ability of numerous pathogens to cause infection.
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Affiliation(s)
- Kyle P Grim
- Department of Microbiology, University of Illinois Urbana-Champaign, Urbana, Illinois, USA
| | - Brian San Francisco
- Institute for Genomic Biology, University of Illinois Urbana-Champaign, Urbana, Illinois, USA
| | - Jana N Radin
- Department of Microbiology, University of Illinois Urbana-Champaign, Urbana, Illinois, USA
| | - Erin B Brazel
- Research Centre for Infectious Diseases, School of Biological Sciences, University of Adelaide, Adelaide, South Australia, Australia
| | - Jessica L Kelliher
- Department of Microbiology, University of Illinois Urbana-Champaign, Urbana, Illinois, USA
| | - Paola K Párraga Solórzano
- Department of Microbiology, University of Illinois Urbana-Champaign, Urbana, Illinois, USA
- Departamento de Ciencias de la Vida, Universidad de las Fuerzas Armadas ESPE, Sangolquí, Ecuador
| | - Philip C Kim
- Department of Microbiology, University of Illinois Urbana-Champaign, Urbana, Illinois, USA
| | - Christopher A McDevitt
- Research Centre for Infectious Diseases, School of Biological Sciences, University of Adelaide, Adelaide, South Australia, Australia
| | - Thomas E Kehl-Fie
- Department of Microbiology, University of Illinois Urbana-Champaign, Urbana, Illinois, USA
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7
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Martin JE, Edmonds KA, Bruce KE, Campanello GC, Eijkelkamp BA, Brazel EB, McDevitt CA, Winkler ME, Giedroc DP. The zinc efflux activator SczA protects Streptococcus pneumoniae serotype 2 D39 from intracellular zinc toxicity. Mol Microbiol 2017; 104:636-651. [PMID: 28249108 DOI: 10.1111/mmi.13654] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 02/21/2017] [Indexed: 12/19/2022]
Abstract
Zinc is an essential trace element that serves as a catalytic cofactor in metalloenzymes and a structural element in proteins involved in general metabolism and cellular defenses of pathogenic bacteria. Despite its importance, high zinc levels can impair cellular processes, inhibiting growth of many pathogenic bacteria, including the major respiratory pathogen Streptococcus pneumoniae. Zinc intoxication is prevented in S. pneumoniae by expression of the zinc exporter CzcD, whose expression is activated by the novel TetR-family transcriptional zinc-sensing regulator SczA. How zinc bioavailability triggers activation of SczA is unknown. It is shown here through functional studies in S. pneumoniae that an unannotated homodimeric TetR from S. agalactiae (PDB 3KKC) is the bona fide zinc efflux regulator SczA, and binds two zinc ions per protomer. Mutagenesis analysis reveals two metal binding sites, termed A and B, located on opposite sides of the SczA C-terminal regulatory domain. In vivo, the A- and B-site SczA mutant variants impact S. pneumoniae resistance to zinc toxicity and survival in infected macrophages. A model is proposed for S. pneumoniae SczA function in which both A- and B-sites were required for transcriptional activation of czcD expression, with the A-site serving as the evolutionarily conserved intracellular sensing site in SczAs.
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Affiliation(s)
- Julia E Martin
- Department of Chemistry, Indiana University, Bloomington, IN, 47405-7005, USA
| | - Katherine A Edmonds
- Department of Chemistry, Indiana University, Bloomington, IN, 47405-7005, USA
| | - Kevin E Bruce
- Department of Biology, Indiana University, Bloomington, IN, 47405-7005, USA
| | | | - Bart A Eijkelkamp
- Research Centre for Infectious Diseases, School of Biological Sciences, the University of Adelaide, SA, 5005, Australia
| | - Erin B Brazel
- Research Centre for Infectious Diseases, School of Biological Sciences, the University of Adelaide, SA, 5005, Australia
| | - Christopher A McDevitt
- Research Centre for Infectious Diseases, School of Biological Sciences, the University of Adelaide, SA, 5005, Australia
| | - Malcolm E Winkler
- Department of Biology, Indiana University, Bloomington, IN, 47405-7005, USA
| | - David P Giedroc
- Department of Chemistry, Indiana University, Bloomington, IN, 47405-7005, USA
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