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Anuradha C, Mol PP, Chandrasekar A, Backiyarani S, Thangavelu R, Selvarajan R. Unveiling the dynamic expression of PR-1 during Musa spp. infection by Fusarium oxysporum fsp. Cubense: a cloning and characterization study. Mol Biol Rep 2024; 51:362. [PMID: 38403791 DOI: 10.1007/s11033-024-09258-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2023] [Accepted: 01/15/2024] [Indexed: 02/27/2024]
Abstract
BACKGROUND Pathogen-related proteins (PR) are pivotal in plant defense, combating diverse biotic and abiotic stresses. While multiple gene families contribute to banana resistance against Fusarium oxysporum f sp. cubense (Foc), Pseudocercospora eumusae, and Pratylenchus coffeae, the significance of PR-1 genes in defense is paramount. METHODS Three PR-1 genes, up-regulated under diverse biotic stresses, were cloned from both resistant and susceptible cultivars of Foc, P. eumusae, and P. coffeae. Molecular characterization, phylogenetic analysis, and docking studies with the Foc TR4 CP gene were conducted. RESULTS Through transcriptomic and real-time studies, three PR-1 genes (Ma02_g15050, Ma02_g15060, and Ma04_g34800) from Musa spp. were identified. These genes exhibited significant up-regulation in resistant cultivars when exposed to Foc, P. eumusae, and P. coffeae. Cloning of these genes was successfully performed from both resistant and susceptible cultivars of Foc race 1 and TR4, P. eumusae, and P. coffeae. Distinct characteristics were observed among the PR-1 genes, with groups 1 and 2 being acidic with signal peptides, and group 3 being basic without signal peptides. All cloned PR-1 proteins belonged to the CAP superfamily (PF00188). Phylogenetic analysis revealed clustering patterns for acidic PR-1 proteins, and KEGG orthology showed associations with vital pathways, including MAPK signaling, plant hormone signal transduction, and plant-pathogen interaction. Secondary and tertiary structure analyses confirmed sequence conservation across studied species. Docking studies explored interactions between the cerato-platanin (CP) gene from Foc TR4 and Ma02_g15060 from banana, suggesting the potential hindrance of PR-1 antifungal activity through direct interaction. CONCLUSIONS The findings underscore the crucial role of cloned PR-1 genes in banana plant defense mechanisms against a broad spectrum of biotic stresses. These genes, especially those in groups 1 and 2, hold promise as candidates for developing stress-tolerant banana cultivars. The study provides valuable insights into the molecular aspects of banana defense strategies, emphasizing the potential applications of PR-1 genes in enhancing banana resilience.
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Affiliation(s)
- Chelliah Anuradha
- ICAR-National Research Centre for Banana, Thogamalai Road, Thayanur Post, Tiruchirappalli, Tamil Nadu, 620 102, India.
| | - Punchakkara Prashina Mol
- ICAR-National Research Centre for Banana, Thogamalai Road, Thayanur Post, Tiruchirappalli, Tamil Nadu, 620 102, India
| | - Arumugam Chandrasekar
- ICAR-National Research Centre for Banana, Thogamalai Road, Thayanur Post, Tiruchirappalli, Tamil Nadu, 620 102, India
| | - Suthanthiram Backiyarani
- ICAR-National Research Centre for Banana, Thogamalai Road, Thayanur Post, Tiruchirappalli, Tamil Nadu, 620 102, India
| | - Raman Thangavelu
- ICAR-National Research Centre for Banana, Thogamalai Road, Thayanur Post, Tiruchirappalli, Tamil Nadu, 620 102, India
| | - Ramasamy Selvarajan
- ICAR-National Research Centre for Banana, Thogamalai Road, Thayanur Post, Tiruchirappalli, Tamil Nadu, 620 102, India
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2
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Zwack EE, Chen Z, Devlin JC, Li Z, Zheng X, Weinstock A, Lacey KA, Fisher EA, Fenyö D, Ruggles KV, Loke P, Torres VJ. Staphylococcus aureus induces a muted host response in human blood that blunts the recruitment of neutrophils. Proc Natl Acad Sci U S A 2022; 119:e2123017119. [PMID: 35881802 PMCID: PMC9351360 DOI: 10.1073/pnas.2123017119] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2021] [Accepted: 05/29/2022] [Indexed: 11/18/2022] Open
Abstract
Staphylococcus aureus is an opportunistic pathogen and chief among bloodstream-infecting bacteria. S. aureus produces an array of human-specific virulence factors that may contribute to immune suppression. Here, we defined the response of primary human phagocytes following infection with S. aureus using RNA-sequencing (RNA-Seq). We found that the overall transcriptional response to S. aureus was weak both in the number of genes and in the magnitude of response. Using an ex vivo bacteremia model with fresh human blood, we uncovered that infection with S. aureus resulted in the down-regulation of genes related to innate immune response and cytokine and chemokine signaling. This muted transcriptional response was conserved across diverse S. aureus clones but absent in blood exposed to heat-killed S. aureus or blood infected with the less virulent staphylococcal species Staphylococcus epidermidis. Notably, this signature was also present in patients with S. aureus bacteremia. We identified the master regulator S. aureus exoprotein expression (SaeRS) and the SaeRS-regulated pore-forming toxins as key mediators of the transcriptional suppression. The S. aureus-mediated suppression of chemokine and cytokine transcription was reflected by circulating protein levels in the plasma. Wild-type S. aureus elicited a soluble milieu that was restrictive in the recruitment of human neutrophils compared with strains lacking saeRS. Thus, S. aureus blunts the inflammatory response resulting in impaired neutrophil recruitment, which could promote the survival of the pathogen during invasive infection.
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Affiliation(s)
- Erin E. Zwack
- Department of Microbiology, New York University Grossman School of Medicine, New York, NY 10016
| | - Ze Chen
- Department of Microbiology, New York University Grossman School of Medicine, New York, NY 10016
| | - Joseph C. Devlin
- Department of Microbiology, New York University Grossman School of Medicine, New York, NY 10016
| | - Zhi Li
- Institute for Systems Genetics, New York University Grossman School of Medicine, New York, NY 10016
| | - Xuhui Zheng
- Department of Microbiology, New York University Grossman School of Medicine, New York, NY 10016
| | - Ada Weinstock
- Department of Medicine Cardiology, New York University Grossman School of Medicine, New York, NY 10016
| | - Keenan A. Lacey
- Department of Microbiology, New York University Grossman School of Medicine, New York, NY 10016
| | - Edward A. Fisher
- Department of Microbiology, New York University Grossman School of Medicine, New York, NY 10016
- Department of Medicine Cardiology, New York University Grossman School of Medicine, New York, NY 10016
| | - David Fenyö
- Institute for Systems Genetics, New York University Grossman School of Medicine, New York, NY 10016
- Department for Biochemistry and Molecular Pharmacology, New York University Grossman School of Medicine, New York, NY 10016
| | - Kelly V. Ruggles
- Institute for Systems Genetics, New York University Grossman School of Medicine, New York, NY 10016
- Division of Translational Medicine, Department of Medicine, New York University Grossman School of Medicine, New York, NY 10016
| | - P’ng Loke
- Department of Microbiology, New York University Grossman School of Medicine, New York, NY 10016
- Laboratory of Parasitic Diseases, National Institute of Allergy and Infectious Diseases, NIH, Bethesda, MD 20892
| | - Victor J. Torres
- Department of Microbiology, New York University Grossman School of Medicine, New York, NY 10016
- Antimicrobial-Resistant Pathogens Program, New York University Grossman School of Medicine, New York, NY 10016
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3
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Abstract
Methicillin-resistant Staphylococcus aureus (MRSA) is one of the most common causes of hospital-acquired pneumonia. To better manage patients with MRSA pneumonia, we require a greater understanding of the host-pathogen interactions during infection. MRSA research focuses on highly virulent and cytotoxic strains, which demonstrate robust phenotypes in animal models of infection. However, nosocomial infections are often caused by hospital-acquired MRSA (HA-MRSA) isolates that exhibit low cytotoxicity and few or no phenotypes in mice, thereby confounding mechanistic studies of pathogenesis. Consequently, virulence pathways utilized by HA-MRSA in nosocomial pneumonia are largely unknown. Here, we report that conditioning mice with broad-spectrum antibiotics lowers the barrier to pneumonia, thereby transforming otherwise avirulent HA-MRSA isolates into lethal pathogens. HA-MRSA isolates are avirulent in gnotobiotic mice, mimicking results in conventional animals. Thus, the observed enhanced susceptibility to infection in antibiotic-treated mice is not due to depletion of the microbiota. More generally, we found that antibiotic conditioning leads to increased susceptibility to infection by diverse antimicrobial-resistant (AMR) pathogens of low virulence. Treatment with antibiotics leads to dehydration and malnutrition, suggesting a potential role for these clinically relevant and reducible hospital complications in susceptibility to pathogens. In sum, the model described here mitigates the impact of low virulence in immunocompetent mice, providing a convenient model to gain fundamental insight into the pathogenesis of nosocomial pathogens.
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4
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Zheng X, Ma SX, St. John A, Torres VJ. The Major Autolysin Atl Regulates the Virulence of Staphylococcus aureus by Controlling the Sorting of LukAB. Infect Immun 2022; 90:e0005622. [PMID: 35258336 PMCID: PMC9022505 DOI: 10.1128/iai.00056-22] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2022] [Accepted: 02/01/2022] [Indexed: 01/14/2023] Open
Abstract
Infections caused by the Gram-positive bacterium Staphylococcus aureus remain a significant health threat globally. The production of bicomponent pore-forming leukocidins plays an important role in S. aureus pathogenesis. Transcriptionally, these toxins are primarily regulated by the Sae and Agr regulatory systems. However, the posttranslational regulation of these toxins is largely unexplored. In particular, one of the leukocidins, LukAB, has been shown to be both secreted into the extracellular milieu and associated with the bacterial cell envelope. Here, we report that a major cell wall hydrolase, autolysin (Atl), controls the sorting of LukAB from the cell envelope to the extracellular milieu, an effect independent of transcriptional regulation. By influencing the sorting of LukAB, Atl modulates S. aureus cytotoxicity toward primary human neutrophils. Mechanistically, we found that the reduction in peptidoglycan cleavage and increased LukAB secretion in the atl mutant can be reversed through the supplementation of exogenous mutanolysin. Altogether, our study revealed that the cell wall hydrolase activity of Atl and the cleavage of peptidoglycan play an important role in controlling the sorting of S. aureus toxins during secretion.
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Affiliation(s)
- Xuhui Zheng
- Department of Microbiology, New York University Grossman School of Medicine, New York, New York, USA
| | - Sheya Xiao Ma
- Department of Microbiology, New York University Grossman School of Medicine, New York, New York, USA
| | - Amelia St. John
- Department of Microbiology, New York University Grossman School of Medicine, New York, New York, USA
| | - Victor J. Torres
- Department of Microbiology, New York University Grossman School of Medicine, New York, New York, USA
- Antimicrobial-Resistant Pathogens Program, New York University Grossman School of Medicine, New York, New York, USA
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5
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The cell envelope of Staphylococcus aureus selectively controls the sorting of virulence factors. Nat Commun 2021; 12:6193. [PMID: 34702812 PMCID: PMC8548510 DOI: 10.1038/s41467-021-26517-z] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2020] [Accepted: 10/05/2021] [Indexed: 11/08/2022] Open
Abstract
Staphylococcus aureus bi-component pore-forming leukocidins are secreted toxins that directly target and lyse immune cells. Intriguingly, one of the leukocidins, Leukocidin AB (LukAB), is found associated with the bacterial cell envelope in addition to secreted into the extracellular milieu. Here, we report that retention of LukAB on the bacterial cells provides S. aureus with a pre-synthesized active toxin that kills immune cells. On the bacteria, LukAB is distributed as discrete foci in two distinct compartments: membrane-proximal and surface-exposed. Through genetic screens, we show that a membrane lipid, lysyl-phosphatidylglycerol (LPG), and lipoteichoic acid (LTA) contribute to LukAB deposition and release. Furthermore, by studying non-covalently surface-bound proteins we discovered that the sorting of additional exoproteins, such as IsaB, Hel, ScaH, and Geh, are also controlled by LPG and LTA. Collectively, our study reveals a multistep secretion system that controls exoprotein storage and protein translocation across the S. aureus cell wall.
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6
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A Fragile Balance: Does Neutrophil Extracellular Trap Formation Drive Pulmonary Disease Progression? Cells 2021; 10:cells10081932. [PMID: 34440701 PMCID: PMC8394734 DOI: 10.3390/cells10081932] [Citation(s) in RCA: 23] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2021] [Revised: 07/22/2021] [Accepted: 07/28/2021] [Indexed: 12/13/2022] Open
Abstract
Neutrophils act as the first line of defense during infection and inflammation. Once activated, they are able to fulfil numerous tasks to fight inflammatory insults while keeping a balanced immune response. Besides well-known functions, such as phagocytosis and degranulation, neutrophils are also able to release "neutrophil extracellular traps" (NETs). In response to most stimuli, the neutrophils release decondensed chromatin in a NADPH oxidase-dependent manner decorated with histones and granule proteins, such as neutrophil elastase, myeloperoxidase, and cathelicidins. Although primarily supposed to prevent microbial dissemination and fight infections, there is increasing evidence that an overwhelming NET response correlates with poor outcome in many diseases. Lung-related diseases especially, such as bacterial pneumonia, cystic fibrosis, chronic obstructive pulmonary disease, aspergillosis, influenza, and COVID-19, are often affected by massive NET formation. Highly vascularized areas as in the lung are susceptible to immunothrombotic events promoted by chromatin fibers. Keeping this fragile equilibrium seems to be the key for an appropriate immune response. Therapies targeting dysregulated NET formation might positively influence many disease progressions. This review highlights recent findings on the pathophysiological influence of NET formation in different bacterial, viral, and non-infectious lung diseases and summarizes medical treatment strategies.
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7
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Tam K, Lacey KA, Devlin JC, Coffre M, Sommerfield A, Chan R, O'Malley A, Koralov SB, Loke P, Torres VJ. Targeting leukocidin-mediated immune evasion protects mice from Staphylococcus aureus bacteremia. J Exp Med 2021; 217:151907. [PMID: 32602902 PMCID: PMC7478724 DOI: 10.1084/jem.20190541] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2019] [Revised: 04/05/2020] [Accepted: 05/08/2020] [Indexed: 12/14/2022] Open
Abstract
Staphylococcus aureus is responsible for various diseases in humans, and recurrent infections are commonly observed. S. aureus produces an array of bicomponent pore-forming toxins that target and kill leukocytes, known collectively as the leukocidins. The contribution of these leukocidins to impair the development of anti–S. aureus adaptive immunity and facilitate reinfection is unclear. Using a murine model of recurrent bacteremia, we demonstrate that infection with a leukocidin mutant results in increased levels of anti–S. aureus antibodies compared with mice infected with the WT parental strain, indicating that leukocidins negatively impact the generation of anti–S. aureus antibodies in vivo. We hypothesized that neutralizing leukocidin-mediated immune subversion by vaccination may shift this host-pathogen interaction in favor of the host. Leukocidin-immunized mice produce potent leukocidin-neutralizing antibodies and robust Th1 and Th17 responses, which collectively protect against bloodstream infections. Altogether, these results demonstrate that blocking leukocidin-mediated immune evasion can promote host protection against S. aureus bloodstream infection.
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Affiliation(s)
- Kayan Tam
- Department of Microbiology, New York University Grossman School of Medicine, New York, NY
| | - Keenan A Lacey
- Department of Microbiology, New York University Grossman School of Medicine, New York, NY
| | - Joseph C Devlin
- Department of Microbiology, New York University Grossman School of Medicine, New York, NY
| | - Maryaline Coffre
- Department of Pathology, New York University Grossman School of Medicine, New York, NY
| | - Alexis Sommerfield
- Department of Microbiology, New York University Grossman School of Medicine, New York, NY
| | - Rita Chan
- Department of Microbiology, New York University Grossman School of Medicine, New York, NY
| | - Aidan O'Malley
- Department of Microbiology, New York University Grossman School of Medicine, New York, NY
| | - Sergei B Koralov
- Department of Pathology, New York University Grossman School of Medicine, New York, NY
| | - P'ng Loke
- Department of Microbiology, New York University Grossman School of Medicine, New York, NY.,Laboratory of Parasitic Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD
| | - Victor J Torres
- Department of Microbiology, New York University Grossman School of Medicine, New York, NY
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8
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Uhlig F, Grundy L, Garcia-Caraballo S, Brierley SM, Foster SJ, Grundy D. Identification of a Quorum Sensing-Dependent Communication Pathway Mediating Bacteria-Gut-Brain Cross Talk. iScience 2020; 23:101695. [PMID: 33163947 PMCID: PMC7607502 DOI: 10.1016/j.isci.2020.101695] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2020] [Revised: 07/03/2020] [Accepted: 10/14/2020] [Indexed: 12/12/2022] Open
Abstract
Despite recently established contributions of the intestinal microbiome to human health and disease, our understanding of bacteria-host communication pathways with regard to the gut-brain axis remains limited. Here we provide evidence that intestinal neurons are able to "sense" bacteria independently of the host immune system. Using supernatants from cultures of the opportunistic pathogen Staphylococcus aureus (S. aureus) we demonstrate the release of mediators with neuromodulatory properties at high population density. These mediators induced a biphasic response in extrinsic sensory afferent nerves, increased membrane permeability in cultured sensory neurons, and altered intestinal motility and secretion. Genetic manipulation of S. aureus revealed two key quorum sensing-regulated classes of pore forming toxins that mediate excitation and inhibition of extrinsic sensory nerves, respectively. As such, bacterial mediators have the potential to directly modulate gut-brain communication to influence intestinal symptoms and reflex function in vivo, contributing to homeostatic, behavioral, and sensory consequences of infection.
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Affiliation(s)
- Friederike Uhlig
- Department of Biomedical Science, University of Sheffield, Sheffield, UK
| | - Luke Grundy
- Visceral Pain Research Group, College of Medicine and Public Health, Flinders Health and Medical Research Institute (FHMRI), Flinders University, Bedford Park, SA, Australia
- Hopwood Centre for Neurobiology, Lifelong Health Theme, South Australian Health and Medical Research Institute (SAHMRI), North Terrace, Adelaide, SA, Australia
- Discipline of Medicine, University of Adelaide, Adelaide, SA, Australia
| | - Sonia Garcia-Caraballo
- Visceral Pain Research Group, College of Medicine and Public Health, Flinders Health and Medical Research Institute (FHMRI), Flinders University, Bedford Park, SA, Australia
- Hopwood Centre for Neurobiology, Lifelong Health Theme, South Australian Health and Medical Research Institute (SAHMRI), North Terrace, Adelaide, SA, Australia
- Discipline of Medicine, University of Adelaide, Adelaide, SA, Australia
| | - Stuart M. Brierley
- Visceral Pain Research Group, College of Medicine and Public Health, Flinders Health and Medical Research Institute (FHMRI), Flinders University, Bedford Park, SA, Australia
- Hopwood Centre for Neurobiology, Lifelong Health Theme, South Australian Health and Medical Research Institute (SAHMRI), North Terrace, Adelaide, SA, Australia
- Discipline of Medicine, University of Adelaide, Adelaide, SA, Australia
| | - Simon J. Foster
- Department of Molecular Biology and Biotechnology, University of Sheffield, Sheffield, UK
- Florey Institute, University of Sheffield, Sheffield, UK
| | - David Grundy
- Department of Biomedical Science, University of Sheffield, Sheffield, UK
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9
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Bhattacharya M, Berends ETM, Zheng X, Hill PJ, Chan R, Torres VJ, Wozniak DJ. Leukocidins and the Nuclease Nuc Prevent Neutrophil-Mediated Killing of Staphylococcus aureus Biofilms. Infect Immun 2020; 88:e00372-20. [PMID: 32719153 PMCID: PMC7504955 DOI: 10.1128/iai.00372-20] [Citation(s) in RCA: 30] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2020] [Accepted: 07/17/2020] [Indexed: 02/07/2023] Open
Abstract
Bacterial biofilms are linked with chronic infections and have properties distinct from those of planktonic, single-celled bacteria. The virulence mechanisms associated with Staphylococcus aureus biofilms are becoming better understood. Human neutrophils are critical for the innate immune response to S. aureus infection. Here, we describe two virulence strategies that converge to promote the ability of S. aureus biofilms to evade killing by neutrophils. Specifically, we show that while neutrophils exposed to S. aureus biofilms produce extracellular traps (NETs) and phagocytose bacteria, both mechanisms are inefficient in clearance of the biofilm biomass. This is attributed to the leukocidin LukAB, which promotes S. aureus survival during phagocytosis. We also show that the persistence of biofilm bacteria trapped in NETs is facilitated by S. aureus nuclease (Nuc)-mediated degradation of NET DNA. This study describes key aspects of the interaction between primary human neutrophils and S. aureus biofilms and provides insight into how S. aureus evades the neutrophil response to cause persistent infections.
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Affiliation(s)
| | - Evelien T M Berends
- Department of Microbiology, New York University School of Medicine, New York, New York, USA
| | - Xuhui Zheng
- Department of Microbiology, New York University School of Medicine, New York, New York, USA
| | - Preston J Hill
- Department of Microbial Infection and Immunity, Ohio State University, Columbus, Ohio, USA
| | - Rita Chan
- Department of Microbiology, New York University School of Medicine, New York, New York, USA
| | - Victor J Torres
- Department of Microbiology, New York University School of Medicine, New York, New York, USA
| | - Daniel J Wozniak
- Department of Microbiology, Ohio State University, Columbus, Ohio, USA
- Department of Microbial Infection and Immunity, Ohio State University, Columbus, Ohio, USA
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10
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Sause WE, Balasubramanian D, Irnov I, Copin R, Sullivan MJ, Sommerfield A, Chan R, Dhabaria A, Askenazi M, Ueberheide B, Shopsin B, van Bakel H, Torres VJ. The purine biosynthesis regulator PurR moonlights as a virulence regulator in Staphylococcus aureus. Proc Natl Acad Sci U S A 2019; 116:13563-13572. [PMID: 31217288 PMCID: PMC6613142 DOI: 10.1073/pnas.1904280116] [Citation(s) in RCA: 43] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
The pathogen Staphylococcus aureus colonizes and infects a variety of different sites within the human body. To adapt to these different environments, S. aureus relies on a complex and finely tuned regulatory network. While some of these networks have been well-elucidated, the functions of more than 50% of the transcriptional regulators in S. aureus remain unexplored. Here, we assess the contribution of the LacI family of metabolic regulators to staphylococcal virulence. We found that inactivating the purine biosynthesis regulator purR resulted in a strain that was acutely virulent in bloodstream infection models in mice and in ex vivo models using primary human neutrophils. Remarkably, these enhanced pathogenic traits are independent of purine biosynthesis, as the purR mutant was still highly virulent in the presence of mutations that disrupt PurR's canonical role. Through the use of transcriptomics coupled with proteomics, we revealed that a number of virulence factors are differentially regulated in the absence of purR Indeed, we demonstrate that PurR directly binds to the promoters of genes encoding virulence factors and to master regulators of virulence. These results guided us into further ex vivo and in vivo studies, where we discovered that S. aureus toxins drive the death of human phagocytes and mice, whereas the surface adhesin FnbA contributes to the increased bacterial burden observed in the purR mutant. Thus, S. aureus repurposes a metabolic regulator to directly control the expression of virulence factors, and by doing so, tempers its pathogenesis.
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Affiliation(s)
- William E Sause
- Department of Microbiology, New York University School of Medicine, New York, NY 10016
| | - Divya Balasubramanian
- Department of Microbiology, New York University School of Medicine, New York, NY 10016
| | - Irnov Irnov
- Department of Microbiology, New York University School of Medicine, New York, NY 10016
| | - Richard Copin
- Department of Microbiology, New York University School of Medicine, New York, NY 10016
- Division of Infectious Diseases and Immunology, Department of Medicine, New York University School of Medicine, New York, NY 10016
| | - Mitchell J Sullivan
- Department of Genetics and Genomic Sciences, Icahn School of Medicine at Mount Sinai, New York, NY 10029
| | - Alexis Sommerfield
- Department of Microbiology, New York University School of Medicine, New York, NY 10016
| | - Rita Chan
- Department of Microbiology, New York University School of Medicine, New York, NY 10016
| | - Avantika Dhabaria
- Proteomics Laboratory, New York University School of Medicine, New York, NY 10016
- Division of Advanced Research, New York University School of Medicine, New York, NY 10016
| | - Manor Askenazi
- Department of Biochemistry and Molecular Pharmacology, New York University School of Medicine, New York, NY 10016
- Biomedical Hosting LLC, Arlington, MA 02474
| | - Beatrix Ueberheide
- Proteomics Laboratory, New York University School of Medicine, New York, NY 10016
- Division of Advanced Research, New York University School of Medicine, New York, NY 10016
- Department of Biochemistry and Molecular Pharmacology, New York University School of Medicine, New York, NY 10016
| | - Bo Shopsin
- Department of Microbiology, New York University School of Medicine, New York, NY 10016
- Division of Infectious Diseases and Immunology, Department of Medicine, New York University School of Medicine, New York, NY 10016
| | - Harm van Bakel
- Department of Genetics and Genomic Sciences, Icahn School of Medicine at Mount Sinai, New York, NY 10029
- Icahn Institute for Genomics and Multiscale Biology, Icahn School of Medicine at Mount Sinai, New York, NY 10029
| | - Victor J Torres
- Department of Microbiology, New York University School of Medicine, New York, NY 10016;
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11
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Genome Plasticity of agr-Defective Staphylococcus aureus during Clinical Infection. Infect Immun 2018; 86:IAI.00331-18. [PMID: 30061376 PMCID: PMC6204747 DOI: 10.1128/iai.00331-18] [Citation(s) in RCA: 43] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2018] [Accepted: 07/21/2018] [Indexed: 01/05/2023] Open
Abstract
Therapy for bacteremia caused by Staphylococcus aureus is often ineffective, even when treatment conditions are optimal according to experimental protocols. Adapted subclones, such as those bearing mutations that attenuate agr-mediated virulence activation, are associated with persistent infection and patient mortality. Therapy for bacteremia caused by Staphylococcus aureus is often ineffective, even when treatment conditions are optimal according to experimental protocols. Adapted subclones, such as those bearing mutations that attenuate agr-mediated virulence activation, are associated with persistent infection and patient mortality. To identify additional alterations in agr-defective mutants, we sequenced and assembled the complete genomes of clone pairs from colonizing and infected sites of several patients in whom S. aureus demonstrated a within-host loss of agr function. We report that events associated with agr inactivation result in agr-defective blood and nares strain pairs that are enriched in mutations compared to pairs from wild-type controls. The random distribution of mutations between colonizing and infecting strains from the same patient, and between strains from different patients, suggests that much of the genetic complexity of agr-defective strains results from prolonged infection or therapy-induced stress. However, in one of the agr-defective infecting strains, multiple genetic changes resulted in increased virulence in a murine model of bloodstream infection, bypassing the mutation of agr and raising the possibility that some changes were selected. Expression profiling correlated the elevated virulence of this agr-defective mutant to restored expression of the agr-regulated ESAT6-like type VII secretion system, a known virulence factor. Thus, additional mutations outside the agr locus can contribute to diversification and adaptation during infection by S. aureus agr mutants associated with poor patient outcomes.
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12
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Staphylococcus aureus biofilms release leukocidins to elicit extracellular trap formation and evade neutrophil-mediated killing. Proc Natl Acad Sci U S A 2018; 115:7416-7421. [PMID: 29941565 DOI: 10.1073/pnas.1721949115] [Citation(s) in RCA: 127] [Impact Index Per Article: 21.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Bacterial biofilms efficiently evade immune defenses, greatly complicating the prognosis of chronic infections. How methicillin-resistant Staphylococcus aureus (MRSA) biofilms evade host immune defenses is largely unknown. This study describes some of the major mechanisms required for S. aureus biofilms to evade the innate immune response and provides evidence of key virulence factors required for survival and persistence of bacteria during chronic infections. Neutrophils are the most abundant white blood cells in circulation, playing crucial roles in the control and elimination of bacterial pathogens. Specifically, here we show that, unlike single-celled populations, S. aureus biofilms rapidly skew neutrophils toward neutrophil extracellular trap (NET) formation through the combined activity of leukocidins Panton-Valentine leukocidin and γ-hemolysin AB. By eliciting this response, S. aureus was able to persist, as the antimicrobial activity of released NETs was ineffective at clearing biofilm bacteria. Indeed, these studies suggest that NETs could inadvertently potentiate biofilm infections. Last, chronic infection in a porcine burn wound model clearly demonstrated that leukocidins are required for "NETosis" and facilitate bacterial survival in vivo.
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Harper L, Balasubramanian D, Ohneck EA, Sause WE, Chapman J, Mejia-Sosa B, Lhakhang T, Heguy A, Tsirigos A, Ueberheide B, Boyd JM, Lun DS, Torres VJ. Staphylococcus aureus Responds to the Central Metabolite Pyruvate To Regulate Virulence. mBio 2018; 9:e02272-17. [PMID: 29362239 PMCID: PMC5784258 DOI: 10.1128/mbio.02272-17] [Citation(s) in RCA: 62] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2017] [Accepted: 12/20/2017] [Indexed: 01/08/2023] Open
Abstract
Staphylococcus aureus is a versatile bacterial pathogen that can cause significant disease burden and mortality. Like other pathogens, S. aureus must adapt to its environment to produce virulence factors to survive the immune responses evoked by infection. Despite the importance of environmental signals for S. aureus pathogenicity, only a limited number of these signals have been investigated in detail for their ability to modulate virulence. Here we show that pyruvate, a central metabolite, causes alterations in the overall metabolic flux of S. aureus and enhances its pathogenicity. We demonstrate that pyruvate induces the production of virulence factors such as the pore-forming leucocidins and that this induction results in increased virulence of community-acquired methicillin-resistant S. aureus (CA-MRSA) clone USA300. Specifically, we show that an efficient "pyruvate response" requires the activation of S. aureus master regulators AgrAC and SaeRS as well as the ArlRS two-component system. Altogether, our report further establishes a strong relationship between metabolism and virulence and identifies pyruvate as a novel regulatory signal for the coordination of the S. aureus virulon through intricate regulatory networks.IMPORTANCE Delineation of the influence of host-derived small molecules on the makeup of human pathogens is a growing field in understanding host-pathogen interactions. S. aureus is a prominent pathogen that colonizes up to one-third of the human population and can cause serious infections that result in mortality in ~15% of cases. Here, we show that pyruvate, a key nutrient and central metabolite, causes global changes to the metabolic flux of S. aureus and activates regulatory networks that allow significant increases in the production of leucocidins. These and other virulence factors are critical for S. aureus to infect diverse host niches, initiate infections, and effectively subvert host immune responses. Understanding how environmental signals, particularly ones that are essential to and prominent in the human host, affect virulence will allow us to better understand pathogenicity and consider more-targeted approaches to tackling the current S. aureus epidemic.
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Affiliation(s)
- Lamia Harper
- Department of Microbiology, New York University School of Medicine, Alexandria Center for Life Science, New York, New York, USA
| | - Divya Balasubramanian
- Department of Microbiology, New York University School of Medicine, Alexandria Center for Life Science, New York, New York, USA
| | - Elizabeth A Ohneck
- Department of Microbiology, New York University School of Medicine, Alexandria Center for Life Science, New York, New York, USA
| | - William E Sause
- Department of Microbiology, New York University School of Medicine, Alexandria Center for Life Science, New York, New York, USA
| | - Jessica Chapman
- Proteomics Resource Center, Office of Collaborative Science, NYU School of Medicine, New York, New York, USA
| | - Bryan Mejia-Sosa
- Center for Computational and Integrative Biology and Department of Computer Science, Rutgers University, Camden, New Jersey, USA
| | - Tenzin Lhakhang
- Applied Bioinformatics Center, Office of Collaborative Science, NYU School of Medicine, New York, New York, USA
| | - Adriana Heguy
- Genome Technology Center, Office of Collaborative Science, NYU School of Medicine, New York, New York, USA
| | - Aristotelis Tsirigos
- Applied Bioinformatics Center, Office of Collaborative Science, NYU School of Medicine, New York, New York, USA
| | - Beatrix Ueberheide
- Proteomics Resource Center, Office of Collaborative Science, NYU School of Medicine, New York, New York, USA
| | - Jeffrey M Boyd
- Department of Biochemistry and Microbiology, Rutgers University, New Brunswick, New Jersey, USA
| | - Desmond S Lun
- Center for Computational and Integrative Biology and Department of Computer Science, Rutgers University, Camden, New Jersey, USA
| | - Victor J Torres
- Department of Microbiology, New York University School of Medicine, Alexandria Center for Life Science, New York, New York, USA
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Rouha H, Weber S, Janesch P, Maierhofer B, Gross K, Dolezilkova I, Mirkina I, Visram ZC, Malafa S, Stulik L, Badarau A, Nagy E. Disarming Staphylococcus aureus from destroying human cells by simultaneously neutralizing six cytotoxins with two human monoclonal antibodies. Virulence 2017; 9:231-247. [PMID: 29099326 PMCID: PMC5955178 DOI: 10.1080/21505594.2017.1391447] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Pathogenesis of Staphylococcus aureus is increasingly recognized to be driven by powerful toxins. Staphylococcus aureus employs up to six pore-forming toxins to subvert the human host defense and to promote bacterial invasion: alpha-hemolysin that disrupts epithelial and endothelial barriers and five leukocidins that lyse phagocytes involved in bacterial clearance. Previously, we described two human monoclonal antibodies (mAbs), ASN-1 that neutralizes alpha-hemolysin and four leukocidins (LukSF-PV, LukED, HlgAB, HlgCB), and ASN-2 that inactivates the 5th leukocidin, LukGH. In this study we tested the individual and combined effects of ASN-1 and ASN-2 in multiple in vitro models employing relevant human target cells. We found that diverse S. aureus isolates with different genetic backgrounds (based on MLST- and spa-typing) and antibiotic sensitivity (both MRSA and MSSA) displayed greatly different cytotoxin expression patterns influenced by the type of growth medium used. Both mAbs were required to fully prevent the lysis of human neutrophils exposed to the mixture of recombinant cytotoxins or native toxins present in the culture supernatants of S. aureus isolates. Flow cytometry confirmed the protective effects of ASN-1 + ASN-2 (known as ASN100) on granulocytes, monocytes, NK-cells and T-lymphocytes. ASN-1 alone preserved the integrity of a 3D-primary culture of human tracheal/bronchial mucociliary epithelial tissue infected with S. aureus. We conclude that simultaneous inhibition of alpha-hemolysin and five leukocidins by ASN100 blocks cytolytic activity of S. aureus towards human target cells in vitro.
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Affiliation(s)
- Harald Rouha
- a Arsanis Biosciences, Helmut-Qualtinger-Gasse 2, Campus Vienna Biocenter , Vienna , Austria
| | - Susanne Weber
- a Arsanis Biosciences, Helmut-Qualtinger-Gasse 2, Campus Vienna Biocenter , Vienna , Austria
| | - Philipp Janesch
- a Arsanis Biosciences, Helmut-Qualtinger-Gasse 2, Campus Vienna Biocenter , Vienna , Austria
| | - Barbara Maierhofer
- a Arsanis Biosciences, Helmut-Qualtinger-Gasse 2, Campus Vienna Biocenter , Vienna , Austria
| | - Karin Gross
- a Arsanis Biosciences, Helmut-Qualtinger-Gasse 2, Campus Vienna Biocenter , Vienna , Austria
| | - Ivana Dolezilkova
- a Arsanis Biosciences, Helmut-Qualtinger-Gasse 2, Campus Vienna Biocenter , Vienna , Austria
| | - Irina Mirkina
- a Arsanis Biosciences, Helmut-Qualtinger-Gasse 2, Campus Vienna Biocenter , Vienna , Austria
| | - Zehra C Visram
- a Arsanis Biosciences, Helmut-Qualtinger-Gasse 2, Campus Vienna Biocenter , Vienna , Austria
| | - Stefan Malafa
- a Arsanis Biosciences, Helmut-Qualtinger-Gasse 2, Campus Vienna Biocenter , Vienna , Austria
| | - Lukas Stulik
- a Arsanis Biosciences, Helmut-Qualtinger-Gasse 2, Campus Vienna Biocenter , Vienna , Austria
| | - Adriana Badarau
- a Arsanis Biosciences, Helmut-Qualtinger-Gasse 2, Campus Vienna Biocenter , Vienna , Austria
| | - Eszter Nagy
- a Arsanis Biosciences, Helmut-Qualtinger-Gasse 2, Campus Vienna Biocenter , Vienna , Austria
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Staphylococcus aureus Strain Newman D2C Contains Mutations in Major Regulatory Pathways That Cripple Its Pathogenesis. J Bacteriol 2017; 199:JB.00476-17. [PMID: 28924032 DOI: 10.1128/jb.00476-17] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2017] [Accepted: 09/15/2017] [Indexed: 12/27/2022] Open
Abstract
Staphylococcus aureus is a major human pathogen that imposes a great burden on the health care system. In the development of antistaphylococcal modalities intended to reduce the burden of staphylococcal disease, it is imperative to select appropriate models of S. aureus strains when assessing the efficacy of novel agents. Here, using whole-genome sequencing, we reveal that the commonly used strain Newman D2C from the American Type Culture Collection (ATCC) contains mutations that render the strain essentially avirulent. Importantly, Newman D2C is often inaccurately referred to as simply "Newman" in many publications, leading investigators to believe it is the well-described pathogenic strain Newman. This study reveals that Newman D2C carries a stop mutation in the open reading frame of the virulence gene regulator, agrA In addition, Newman D2C carries a single-nucleotide polymorphism (SNP) in the global virulence regulator gene saeR that results in loss of protein function. This loss of function is highlighted by complementation studies, where the saeR allele from Newman D2C is incapable of restoring functionality to an saeR-null mutant. Additional functional assessment was achieved through the use of biochemical assays for protein secretion, ex vivo intoxications of human immune cells, and in vivo infections. Altogether, our study highlights the importance of judiciously screening for genetic changes in model S. aureus strains when assessing pathogenesis or the efficacy of novel agents. Moreover, we have identified a novel SNP in the virulence regulator gene saeR that directly affects the ability of the protein product to activate S. aureus virulence pathways.IMPORTANCE Staphylococcus aureus is a human pathogen that imposes an enormous burden on health care systems worldwide. This bacterium is capable of evoking a multitude of disease states that can range from self-limiting skin infections to life-threatening bacteremia. To combat these infections, numerous investigations are under way to develop therapeutics capable of thwarting the deadly effects of the bacterium. To generate successful treatments, it is of paramount importance that investigators use suitable models for examining the efficacy of the drugs under study. Here, we demonstrate that a strain of S. aureus commonly used for drug efficacy studies is severely mutated and displays markedly reduced pathogenicity. As such, the organism is an inappropriate model for disease studies.
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El-Rami F, Nelson K, Xu P. Proteomic Approach for Extracting Cytoplasmic Proteins from Streptococcus sanguinis using Mass Spectrometry. ACTA ACUST UNITED AC 2017; 7:50-57. [PMID: 29152022 PMCID: PMC5693382 DOI: 10.5539/jmbr.v7n1p50] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Streptococcus sanguinis is a commensal and early colonizer of oral cavity as well as an opportunistic pathogen of infectious endocarditis. Extracting the soluble proteome of this bacterium provides deep insights about the physiological dynamic changes under different growth and stress conditions, thus defining "proteomic signatures" as targets for therapeutic intervention. In this protocol, we describe an experimentally verified approach to extract maximal cytoplasmic proteins from Streptococcus sanguinis SK36 strain. A combination of procedures was adopted that broke the thick cell wall barrier and minimized denaturation of the intracellular proteome, using optimized buffers and a sonication step. Extracted proteome was quantitated using Pierce BCA Protein Quantitation assay and protein bands were macroscopically assessed by Coomassie Blue staining. Finally, a high resolution detection of the extracted proteins was conducted through Synapt G2Si mass spectrometer, followed by label-free relative quantification via Progenesis QI. In conclusion, this pipeline for proteomic extraction and analysis of soluble proteins provides a fundamental tool in deciphering the biological complexity of Streptococcus sanguinis.
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Affiliation(s)
- Fadi El-Rami
- Philips Institute for Oral Health Research, Virginia Commonwealth University, Richmond, Virginia, USA.,Department of Microbiology and Immunology, Virginia Commonwealth University, Richmond, Virginia, USA
| | - Kristina Nelson
- Chemical and Proteomic Mass Spectrometry Core Facility, Department of Chemistry, Virginia Commonwealth University, Richmond, Virginia, USA
| | - Ping Xu
- Philips Institute for Oral Health Research, Virginia Commonwealth University, Richmond, Virginia, USA.,Department of Microbiology and Immunology, Virginia Commonwealth University, Richmond, Virginia, USA
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17
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Cristea IM. The Host-Pathogen Ecosystem Viewed Through the Prism of Proteomics. Mol Cell Proteomics 2017; 16:S1-S4. [PMID: 28283547 DOI: 10.1074/mcp.e117.068270] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2017] [Revised: 03/10/2017] [Indexed: 12/29/2022] Open
Affiliation(s)
- Ileana M Cristea
- From the ‡Department of Molecular Biology, Princeton University, Princeton, New Jersey 08544
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