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Pruitt EL, Zhang R, Ross DH, Ashford NK, Chen X, Alonzo F, Bush MF, Werth BJ, Xu L. Elucidating the impact of bacterial lipases, human serum albumin, and FASII inhibition on the utilization of exogenous fatty acids by Staphylococcus aureus. mSphere 2023; 8:e0036823. [PMID: 38014966 PMCID: PMC10732024 DOI: 10.1128/msphere.00368-23] [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: 07/06/2023] [Accepted: 10/26/2023] [Indexed: 11/29/2023] Open
Abstract
IMPORTANCE Incorporation of host-derived exogenous fatty acids (eFAs), particularly unsaturated fatty acids (UFAs), by Staphylococcus aureus could affect the bacterial membrane fluidity and susceptibility to antimicrobials. In this work, we found that glycerol ester hydrolase (Geh) is the primary lipase hydrolyzing cholesteryl esters and, to a lesser extent, triglycerides and that human serum albumin (HSA) could serve as a buffer of eFAs, where low levels of HSA facilitate the utilization of eFAs but high levels of HSA inhibit it. The fact that the type II fatty acid synthesis (FASII) inhibitor, AFN-1252, leads to an increase in UFA content even in the absence of eFA suggests that membrane property modulation is part of its mechanism of action. Thus, Geh and/or the FASII system look to be promising targets to enhance S. aureus killing in a host environment by restricting eFA utilization or modulating membrane properties, respectively.
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Affiliation(s)
- Emily L. Pruitt
- Department of Chemistry, University of Washington, Seattle, Washington, USA
| | - Rutan Zhang
- Department of Medicinal Chemistry, University of Washington, Seattle, Washington, USA
| | - Dylan H. Ross
- Department of Medicinal Chemistry, University of Washington, Seattle, Washington, USA
| | | | - Xi Chen
- Department of Microbiology and Immunology, Loyola University Chicago-Stritch School of Medicine, Maywood, Illinois, USA
| | - Francis Alonzo
- Department of Microbiology and Immunology, Loyola University Chicago-Stritch School of Medicine, Maywood, Illinois, USA
| | - Matthew F. Bush
- Department of Chemistry, University of Washington, Seattle, Washington, USA
| | - Brian J. Werth
- Department of Pharmacy, University of Washington, Seattle, Washington, USA
| | - Libin Xu
- Department of Medicinal Chemistry, University of Washington, Seattle, Washington, USA
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2
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Acosta IC, Alonzo F. The Intersection between Bacterial Metabolism and Innate Immunity. J Innate Immun 2023; 15:782-803. [PMID: 37899025 PMCID: PMC10663042 DOI: 10.1159/000534872] [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: 09/14/2023] [Accepted: 10/25/2023] [Indexed: 10/31/2023] Open
Abstract
BACKGROUND The innate immune system is the first line of defense against microbial pathogens and is essential for maintaining good health. If pathogens breach innate barriers, the likelihood of infection is significantly increased. Many bacterial pathogens pose a threat to human health on account of their ability to evade innate immunity and survive in growth-restricted environments. These pathogens have evolved sophisticated strategies to obtain nutrients as well as manipulate innate immune responses, resulting in disease or chronic infection. SUMMARY The relationship between bacterial metabolism and innate immunity is complex. Although aspects of bacterial metabolism can be beneficial to the host, particularly those related to the microbiota and barrier integrity, others can be harmful. Several bacterial pathogens harness metabolism to evade immune responses and persist during infection. The study of these adaptive traits provides insight into the roles of microbial metabolism in pathogenesis that extend beyond energy balance. This review considers recent studies on bacterial metabolic pathways that promote infection by circumventing several facets of the innate immune system. We also discuss relationships between innate immunity and antibiotics and highlight future directions for research in this field. KEY MESSAGES Pathogenic bacteria have a remarkable capacity to harness metabolism to manipulate immune responses and promote pathogenesis. While we are beginning to understand the multifaceted and complex metabolic adaptations that occur during infection, there is still much to uncover with future research.
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Affiliation(s)
- Ivan C Acosta
- Department of Microbiology and Immunology, University of Illinois at Chicago - College of Medicine, Chicago, Illinois, USA
| | - Francis Alonzo
- Department of Microbiology and Immunology, University of Illinois at Chicago - College of Medicine, Chicago, Illinois, USA
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3
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Wang Y, Zheng Y, Qi B, Liu Y, Cheng X, Feng J, Gao W, Li T. α-Lipoic acid alleviates myocardial injury and induces M2b macrophage polarization after myocardial infarction via HMGB1/NF-kB signaling pathway. Int Immunopharmacol 2023; 121:110435. [PMID: 37320869 DOI: 10.1016/j.intimp.2023.110435] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2023] [Revised: 05/29/2023] [Accepted: 05/30/2023] [Indexed: 06/17/2023]
Abstract
BACKGROUND Myocardial infarction (MI) is a serious cardiovascular disease with a poor prognosis. Macrophages are the predominant immune cells in patients with MI and macrophage regulation during the different phases of MI has important consequences for cardiac recovery. Alpha-lipoic acid (ALA) plays a critical role in MI by modulating the number of cardiomyocytes and macrophages. METHODS MI mice were generated by ligating the left anterior descending coronary artery. Macrophages were exposed to hypoxia to establish a hypoxia model and M1 polarization was induced by LPS and IFN-γ. Different groups of macrophages and MI mice were treated with ALA. The cardiomyocytes were treated with various macrophage supernatants and the cardiac function, cytokine levels, and pathology were also analyzed. Factors related to apoptosis, autophagy, reactive oxygen species (ROS), and the mitochondrial membrane potential (MMP) were assessed. Finally, the HMGB1/NF-κB pathway was identified. RESULTS ALA promoted M2b polarization in normal cells and suppressed inflammatory cytokines during hypoxia. ALA inhibited ROS and MMP production in vitro. Supernatants containing ALA inhibited apoptosis and autophagy in hypoxic cardiomyocytes. Moreover, ALA suppressed the HMGB1/NF-κB pathway in macrophages, which may be a potential mechanism for attenuating MI. CONCLUSION ALA alleviates MI and induces M2b polarization via the HMGB1/NF-κB pathway, impeding inflammation, oxidation, apoptosis, and autophagy, and might be a potential strategy for MI treatment.
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Affiliation(s)
- Yuchao Wang
- School of Medicine, Nankai University, Tianjin 300071, China; Department of Heart Center, The Third Central Hospital of Tianjin, 83 Jintang Road, Hedong District, Tianjin 300170, China; Nankai University Affiliated Third Center Hospital, No. 83, Jintang Road, Hedong District, Tianjin 300170, China; Tianjin Key Laboratory of Extracorporeal Life Support for Critical Diseases, Tianjin, China; Tianjin ECMO Treatment and Training Base, Tianjin 300170, China; Artificial Cell Engineering Technology Research Center, Tianjin, China.
| | - Yue Zheng
- School of Medicine, Nankai University, Tianjin 300071, China; Department of Heart Center, The Third Central Hospital of Tianjin, 83 Jintang Road, Hedong District, Tianjin 300170, China; Nankai University Affiliated Third Center Hospital, No. 83, Jintang Road, Hedong District, Tianjin 300170, China; Tianjin Key Laboratory of Extracorporeal Life Support for Critical Diseases, Tianjin, China; Tianjin ECMO Treatment and Training Base, Tianjin 300170, China; Artificial Cell Engineering Technology Research Center, Tianjin, China
| | - Bingcai Qi
- Department of Heart Center, The Third Central Hospital of Tianjin, 83 Jintang Road, Hedong District, Tianjin 300170, China; Nankai University Affiliated Third Center Hospital, No. 83, Jintang Road, Hedong District, Tianjin 300170, China; The Third Central Clinical College of Tianjin Medical University, Tianjin 300170, China; Tianjin Key Laboratory of Extracorporeal Life Support for Critical Diseases, Tianjin, China; Tianjin ECMO Treatment and Training Base, Tianjin 300170, China; Artificial Cell Engineering Technology Research Center, Tianjin, China
| | - Yanwu Liu
- Department of Heart Center, The Third Central Hospital of Tianjin, 83 Jintang Road, Hedong District, Tianjin 300170, China; Nankai University Affiliated Third Center Hospital, No. 83, Jintang Road, Hedong District, Tianjin 300170, China; The Third Central Clinical College of Tianjin Medical University, Tianjin 300170, China; Tianjin Key Laboratory of Extracorporeal Life Support for Critical Diseases, Tianjin, China; Tianjin ECMO Treatment and Training Base, Tianjin 300170, China; Artificial Cell Engineering Technology Research Center, Tianjin, China
| | - Xuan Cheng
- Department of Heart Center, The Third Central Hospital of Tianjin, 83 Jintang Road, Hedong District, Tianjin 300170, China; Nankai University Affiliated Third Center Hospital, No. 83, Jintang Road, Hedong District, Tianjin 300170, China; The Third Central Clinical College of Tianjin Medical University, Tianjin 300170, China; Tianjin Key Laboratory of Extracorporeal Life Support for Critical Diseases, Tianjin, China; Tianjin ECMO Treatment and Training Base, Tianjin 300170, China; Artificial Cell Engineering Technology Research Center, Tianjin, China
| | - Jianyu Feng
- Department of Heart Center, The Third Central Hospital of Tianjin, 83 Jintang Road, Hedong District, Tianjin 300170, China; Nankai University Affiliated Third Center Hospital, No. 83, Jintang Road, Hedong District, Tianjin 300170, China; The Third Central Clinical College of Tianjin Medical University, Tianjin 300170, China; Tianjin Key Laboratory of Extracorporeal Life Support for Critical Diseases, Tianjin, China; Tianjin ECMO Treatment and Training Base, Tianjin 300170, China; Artificial Cell Engineering Technology Research Center, Tianjin, China
| | - Wenqing Gao
- Department of Heart Center, The Third Central Hospital of Tianjin, 83 Jintang Road, Hedong District, Tianjin 300170, China; Nankai University Affiliated Third Center Hospital, No. 83, Jintang Road, Hedong District, Tianjin 300170, China; The Third Central Clinical College of Tianjin Medical University, Tianjin 300170, China; Tianjin Key Laboratory of Extracorporeal Life Support for Critical Diseases, Tianjin, China; Tianjin ECMO Treatment and Training Base, Tianjin 300170, China; Artificial Cell Engineering Technology Research Center, Tianjin, China.
| | - Tong Li
- School of Medicine, Nankai University, Tianjin 300071, China; Department of Heart Center, The Third Central Hospital of Tianjin, 83 Jintang Road, Hedong District, Tianjin 300170, China; Nankai University Affiliated Third Center Hospital, No. 83, Jintang Road, Hedong District, Tianjin 300170, China; The Third Central Clinical College of Tianjin Medical University, Tianjin 300170, China; Tianjin Key Laboratory of Extracorporeal Life Support for Critical Diseases, Tianjin, China; Tianjin ECMO Treatment and Training Base, Tianjin 300170, China; Artificial Cell Engineering Technology Research Center, Tianjin, China.
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4
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Pruitt EL, Zhang R, Ross DH, Ashford NK, Chen X, Alonzo F, Bush MF, Werth BJ, Xu L. Elucidating the Impact of Bacterial Lipases, Human Serum Albumin, and FASII Inhibition on the Utilization of Exogenous Fatty Acids by Staphylococcus aureus. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.06.29.547085. [PMID: 37425828 PMCID: PMC10327171 DOI: 10.1101/2023.06.29.547085] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/11/2023]
Abstract
Staphylococcus aureus only synthesizes straight-chain or branched-chain saturated fatty acids (SCFAs or BCFAs) via the type II fatty acid synthesis (FASII) pathway, but as a highly adaptive pathogen, S. aureus can also utilize host-derived exogenous fatty acids (eFAs), including SCFAs and unsaturated fatty acids (UFAs). S. aureus secretes three lipases, Geh, sal1, and SAUSA300_0641, which could perform the function of releasing fatty acids from host lipids. Once released, the FAs are phosphorylated by the fatty acid kinase, FakA, and incorporated into the bacterial lipids. In this study, we determined the substrate specificity of S. aureus secreted lipases, the effect of human serum albumin (HSA) on eFA incorporation, and the effect of FASII inhibitor, AFN-1252, on eFA incorporation using comprehensive lipidomics. When grown with major donors of fatty acids, cholesteryl esters (CEs) and triglycerides (TGs), Geh was found to be the primary lipase responsible for hydrolyzing CEs, but other lipases could compensate for the function of Geh in hydrolyzing TGs. Lipidomics showed that eFAs were incorporated into all major S. aureus lipid classes and that fatty acid-containing HSA can serve as a source of eFAs. Furthermore, S. aureus grown with UFAs displayed decreased membrane fluidity and increased production of reactive oxygen species (ROS). Exposure to AFN-1252 enhanced UFAs in the bacterial membrane, even without a source of eFAs, indicating a FASII pathway modification. Thus, the incorporation of eFAs alters the S. aureus lipidome, membrane fluidity, and ROS formation, which could affect host-pathogen interactions and susceptibility to membrane-targeting antimicrobials.
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Affiliation(s)
- Emily L. Pruitt
- Department of Chemistry, University of Washington, Seattle, Washington, USA
| | - Rutan Zhang
- Department of Medicinal Chemistry, University of Washington, Seattle, Washington, USA
| | - Dylan H. Ross
- Department of Medicinal Chemistry, University of Washington, Seattle, Washington, USA
| | | | - Xi Chen
- Department of Microbiology and Immunology, Loyola University Chicago-Stritch School of Medicine, Maywood, Illinois, USA
| | - Francis Alonzo
- Department of Microbiology and Immunology, Loyola University Chicago-Stritch School of Medicine, Maywood, Illinois, USA
| | - Matthew F. Bush
- Department of Chemistry, University of Washington, Seattle, Washington, USA
| | - Brian J. Werth
- Department of Pharmacy, University of Washington, Seattle, Washington, USA
| | - Libin Xu
- Department of Medicinal Chemistry, University of Washington, Seattle, Washington, USA
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5
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Polaske TJ, West KHJ, Zhao K, Widner DL, York JT, Blackwell HE. Chemical and biomolecular insights into the Staphylococcus aureus agr quorum sensing system: Current progress and ongoing challenges. Isr J Chem 2023; 63:e202200096. [PMID: 38765792 PMCID: PMC11101167 DOI: 10.1002/ijch.202200096] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2022] [Indexed: 03/19/2023]
Abstract
Staphylococcus aureus is a ubiquitous bacterium that has become a major threat to human health due to its extensive toxin production and tremendous capacity for antibiotic resistance (e.g., MRSA "superbug" infections). Amid a worsening antibiotic resistance crisis, new strategies to combat this deadly microbe that remove the selective pressure of traditional approaches are in high demand. S. aureus utilizes an accessory gene regulator (agr) quorum sensing network to monitor its local cellular population and trigger a devastating communal attack, like an invading horde, once a threshold cell density has been reached. The role of the agr system in a range of disease types is still being unraveled. Herein, we discuss the present-day biochemical understanding of agr along with unresolved details, describe its connection to the progression of infection, and review how chemical strategies have been implemented to study and intercept this signaling pathway. This research is illuminating the potential of agr as an anti-virulence target in S. aureus and should inform the study of similar, yet less studied, agr systems in related bacterial pathogens.
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Affiliation(s)
- Thomas J. Polaske
- Department of Chemistry, University of Wisconsin–Madison, 1101 University Ave., Madison, WI 53706 USA
| | - Korbin H. J. West
- Department of Chemistry, University of Wisconsin–Madison, 1101 University Ave., Madison, WI 53706 USA
| | - Ke Zhao
- Department of Chemistry, University of Wisconsin–Madison, 1101 University Ave., Madison, WI 53706 USA
| | - Danielle L. Widner
- Department of Chemistry, University of Wisconsin–Madison, 1101 University Ave., Madison, WI 53706 USA
| | - Jordan T. York
- Department of Chemistry, University of Wisconsin–Madison, 1101 University Ave., Madison, WI 53706 USA
| | - Helen E. Blackwell
- Department of Chemistry, University of Wisconsin–Madison, 1101 University Ave., Madison, WI 53706 USA
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6
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Morra R, Pratama F, Butterfield T, Tomazetto G, Young K, Lopez R, Dixon N. arfA antisense RNA regulates MscL excretory activity. Life Sci Alliance 2023; 6:e202301954. [PMID: 37012050 PMCID: PMC10070815 DOI: 10.26508/lsa.202301954] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2023] [Revised: 03/20/2023] [Accepted: 03/20/2023] [Indexed: 04/05/2023] Open
Abstract
Excretion of cytoplasmic protein (ECP) is a commonly observed phenomenon in bacteria, and this partial extracellular localisation of the intracellular proteome has been implicated in a variety of stress response mechanisms. In response to hypoosmotic shock and ribosome stalling in Escherichia coli, ECP is dependent upon the presence of the large-conductance mechanosensitive channel and the alternative ribosome-rescue factor A gene products. However, it is not known if a mechanistic link exists between the corresponding genes and the respective stress response pathways. Here, we report that the corresponding mscL and arfA genes are commonly co-located on the genomes of Gammaproteobacteria and display overlap in their respective 3' UTR and 3' CDS. We show this unusual genomic arrangement permits an antisense RNA-mediated regulatory control between mscL and arfA, and this modulates MscL excretory activity in E. coli These findings highlight a mechanistic link between osmotic, translational stress responses and ECP in E. coli, further elucidating the previously unknown regulatory function of arfA sRNA.
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Affiliation(s)
- Rosa Morra
- Department of Chemistry, Manchester Institute of Biotechnology, The University of Manchester, Manchester, UK
| | - Fenryco Pratama
- Department of Chemistry, Manchester Institute of Biotechnology, The University of Manchester, Manchester, UK
- Institut Teknologi Bandung, Bandung, Indonesia
| | - Thomas Butterfield
- Department of Chemistry, Manchester Institute of Biotechnology, The University of Manchester, Manchester, UK
| | - Geizecler Tomazetto
- Department of Chemistry, Manchester Institute of Biotechnology, The University of Manchester, Manchester, UK
| | - Kate Young
- Department of Chemistry, Manchester Institute of Biotechnology, The University of Manchester, Manchester, UK
| | - Ruth Lopez
- Department of Chemistry, Manchester Institute of Biotechnology, The University of Manchester, Manchester, UK
| | - Neil Dixon
- Department of Chemistry, Manchester Institute of Biotechnology, The University of Manchester, Manchester, UK
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7
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Pseudomonas aeruginosa and Staphylococcus aureus Display Differential Proteomic Responses to the Silver(I) Compound, SBC3. Antibiotics (Basel) 2023; 12:antibiotics12020348. [PMID: 36830259 PMCID: PMC9952281 DOI: 10.3390/antibiotics12020348] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2023] [Revised: 01/27/2023] [Accepted: 02/03/2023] [Indexed: 02/10/2023] Open
Abstract
The urgent need to combat antibiotic resistance and develop novel antimicrobial therapies has triggered studies on novel metal-based formulations. N-heterocyclic carbene (NHC) complexes coordinate transition metals to generate a broad range of anticancer and/or antimicrobial agents, with ongoing efforts being made to enhance the lipophilicity and drug stability. The lead silver(I) acetate complex, 1,3-dibenzyl-4,5-diphenylimidazol-2-ylidene (NHC*) (SBC3), has previously demonstrated promising growth and biofilm-inhibiting properties. In this work, the responses of two structurally different bacteria to SBC3 using label-free quantitative proteomics were characterised. Multidrug-resistant Pseudomonas aeruginosa (Gram-negative) and Staphylococcus aureus (Gram-positive) are associated with cystic fibrosis lung colonisation and chronic wound infections, respectively. SBC3 increased the abundance of alginate biosynthesis, the secretion system and drug detoxification proteins in P. aeruginosa, whilst a variety of pathways, including anaerobic respiration, twitching motility and ABC transport, were decreased in abundance. This contrasted the affected pathways in S. aureus, where increased DNA replication/repair and cell redox homeostasis and decreased protein synthesis, lipoylation and glucose metabolism were observed. Increased abundance of cell wall/membrane proteins was indicative of the structural damage induced by SBC3 in both bacteria. These findings show the potential broad applications of SBC3 in treating Gram-positive and Gram-negative bacteria.
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8
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Characterization of MroQ-Dependent Maturation and Export of the Staphylococcus aureus Accessory Gene Regulatory System Autoinducing Peptide. Infect Immun 2022; 90:e0026322. [PMID: 36073934 PMCID: PMC9584314 DOI: 10.1128/iai.00263-22] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
Gram-positive bacteria produce small autoinducing peptides (AIPs), which act to regulate expression of genes that promote adaptive traits, including virulence. The Gram-positive pathogen Staphylococcus aureus generates a cyclic AIP that controls expression of virulence factors via the accessory gene regulatory (Agr) system. S. aureus strains belong to one of four Agr groups (Agr-I, -II, -III, and -IV); each group harbors allelic variants of AgrD, the precursor of AIP. In a prior screen for S. aureus virulence factors, we identified MroQ, a putative peptidase. A ΔmroQ mutant closely resembled a Δagr mutant and had significant defects in AIP production in an Agr-I strain. Here, we show that expression of AgrD-I in a ΔmroQ mutant leads to accumulation of an AIP processing intermediate at the membrane that coincides with a loss of secreted mature AIP, indicating that MroQ promotes maturation of AgrD-I. MroQ is conserved in all Agr sequence variants, suggesting either identical function among all Agr types or activity specific to Agr-I strains. Our data indicate that MroQ is required for AIP maturation and activity in Agr-I, -II, and -IV strains irrespective of background. However, MroQ is not required for Agr-III activity despite an identifiable role in peptide maturation. Isogenic Δagr and Δagr ΔmroQ strains complemented with Agr-I to -IV validated the critical role of MroQ in the generation of active AIP-I, -II, and -IV but not AIP-III. These findings were reinforced by skin infection studies with mice. Our data substantiate the prevailing model that MroQ is a mediator of cyclic peptide maturation.
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9
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Zhang X, Xiong T, Gao L, Wang Y, Liu L, Tian T, Shi Y, Zhang J, Zhao Z, Lu D, Luo P, Zhang W, Cheng P, Jing H, Gou Q, Zeng H, Yan D, Zou Q. Extracellular fibrinogen-binding protein released by intracellular Staphylococcus aureus suppresses host immunity by targeting TRAF3. Nat Commun 2022; 13:5493. [PMID: 36123338 PMCID: PMC9484707 DOI: 10.1038/s41467-022-33205-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2022] [Accepted: 09/08/2022] [Indexed: 11/09/2022] Open
Abstract
Many pathogens secrete effectors to hijack intracellular signaling regulators in host immune cells to promote pathogenesis. However, the pathogenesis of Staphylococcus aureus secretory effectors within host cells is unclear. Here, we report that Staphylococcus aureus secretes extracellular fibrinogen-binding protein (Efb) into the cytoplasm of macrophages to suppress host immunity. Mechanistically, RING finger protein 114, a host E3 ligase, mediates K27-linked ubiquitination of Efb at lysine 71, which facilitates the recruitment of tumor necrosis factor receptor associated factor (TRAF) 3. The binding of Efb to TRAF3 disrupts the formation of the TRAF3/TRAF2/cIAP1 (cellular-inhibitor-of-apoptosis-1) complex, which mediates K48-ubiquitination of TRAF3 to promote degradation, resulting in suppression of the inflammatory signaling cascade. Additionally, the Efb K71R mutant loses the ability to inhibit inflammation and exhibits decreased pathogenicity. Therefore, our findings identify an unrecognized mechanism of Staphylococcus aureus to suppress host defense, which may be a promising target for developing effective anti-Staphylococcus aureus immunomodulators. Staphylococcus aureus secrete numerous effectors to evade or inhibit the host immune response, yet the mechanism underlying the effectors ability to manipulate the signalling pathways of macrophages remain unclear. Authors utilise in vitro and in vivo models to explore the role of extracellular fibrinogen-binding protein (Efb) in immune response modulation and pathogenicity.
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Affiliation(s)
- Xiaokai Zhang
- National Engineering Research Center of Immunological Products, Department of Microbiology and Biochemical Pharmacy, College of Pharmacy, Third Military Medical University, Chongqing, 400038, China
| | - Tingrong Xiong
- National Engineering Research Center of Immunological Products, Department of Microbiology and Biochemical Pharmacy, College of Pharmacy, Third Military Medical University, Chongqing, 400038, China
| | - Lin Gao
- National Engineering Research Center of Immunological Products, Department of Microbiology and Biochemical Pharmacy, College of Pharmacy, Third Military Medical University, Chongqing, 400038, China
| | - Yu Wang
- National Engineering Research Center of Immunological Products, Department of Microbiology and Biochemical Pharmacy, College of Pharmacy, Third Military Medical University, Chongqing, 400038, China.,Department of Basic Courses, NCO School, Third Military Medical University, Shijiazhuang, 050081, China
| | - Luxuan Liu
- College of Medicine, Southwest Jiaotong University, Chengdu, 610083, China
| | - Tian Tian
- National Engineering Research Center of Immunological Products, Department of Microbiology and Biochemical Pharmacy, College of Pharmacy, Third Military Medical University, Chongqing, 400038, China
| | - Yun Shi
- Institute of Biopharmaceutical Research, West China Hospital, Sichuan University, Chengdu, Sichuan, 610041, China
| | - Jinyong Zhang
- National Engineering Research Center of Immunological Products, Department of Microbiology and Biochemical Pharmacy, College of Pharmacy, Third Military Medical University, Chongqing, 400038, China
| | - Zhuo Zhao
- National Engineering Research Center of Immunological Products, Department of Microbiology and Biochemical Pharmacy, College of Pharmacy, Third Military Medical University, Chongqing, 400038, China
| | - Dongshui Lu
- National Engineering Research Center of Immunological Products, Department of Microbiology and Biochemical Pharmacy, College of Pharmacy, Third Military Medical University, Chongqing, 400038, China
| | - Ping Luo
- National Engineering Research Center of Immunological Products, Department of Microbiology and Biochemical Pharmacy, College of Pharmacy, Third Military Medical University, Chongqing, 400038, China
| | - Weijun Zhang
- National Engineering Research Center of Immunological Products, Department of Microbiology and Biochemical Pharmacy, College of Pharmacy, Third Military Medical University, Chongqing, 400038, China
| | - Ping Cheng
- National Engineering Research Center of Immunological Products, Department of Microbiology and Biochemical Pharmacy, College of Pharmacy, Third Military Medical University, Chongqing, 400038, China
| | - Haiming Jing
- National Engineering Research Center of Immunological Products, Department of Microbiology and Biochemical Pharmacy, College of Pharmacy, Third Military Medical University, Chongqing, 400038, China
| | - Qiang Gou
- National Engineering Research Center of Immunological Products, Department of Microbiology and Biochemical Pharmacy, College of Pharmacy, Third Military Medical University, Chongqing, 400038, China
| | - Hao Zeng
- National Engineering Research Center of Immunological Products, Department of Microbiology and Biochemical Pharmacy, College of Pharmacy, Third Military Medical University, Chongqing, 400038, China.
| | - Dapeng Yan
- Department of Immunology, School of Basic Medical Sciences, Shanghai Institute of Infectious Disease and Biosecurity & Shanghai Public Health Clinical Center, Fudan University, Shanghai, 200032, China.
| | - Quanming Zou
- National Engineering Research Center of Immunological Products, Department of Microbiology and Biochemical Pharmacy, College of Pharmacy, Third Military Medical University, Chongqing, 400038, China.
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10
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Agaronyan K, Sharma L, Vaidyanathan B, Glenn K, Yu S, Annicelli C, Wiggen TD, Penningroth MR, Hunter RC, Dela Cruz CS, Medzhitov R. Tissue remodeling by an opportunistic pathogen triggers allergic inflammation. Immunity 2022; 55:895-911.e10. [PMID: 35483356 PMCID: PMC9123649 DOI: 10.1016/j.immuni.2022.04.001] [Citation(s) in RCA: 16] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2021] [Revised: 01/04/2022] [Accepted: 04/04/2022] [Indexed: 01/01/2023]
Abstract
Different effector arms of the immune system are optimized to protect from different classes of pathogens. In some cases, pathogens manipulate the host immune system to promote the wrong type of effector response-a phenomenon known as immune deviation. Typically, immune deviation helps pathogens to avoid destructive immune responses. Here, we report on a type of immune deviation whereby an opportunistic pathogen, Pseudomonas aeruginosa (P. aeruginosa), induces the type 2 immune response resulting in mucin production that is used as an energy source by the pathogen. Specifically, P. aeruginosa-secreted toxin, LasB, processed and activated epithelial amphiregulin to induce type 2 inflammation and mucin production. This "niche remodeling" by P. aeruginosa promoted colonization and, as a by-product, allergic sensitization. Our study thus reveals a type of bacterial immune deviation by increasing nutrient supply. It also uncovers a mechanism of allergic sensitization by a bacterial virulence factor.
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Affiliation(s)
- Karen Agaronyan
- Howard Hughes Medical Institute and Department of Immunobiology, Yale University School of Medicine, New Haven, CT 06520, USA
| | - Lokesh Sharma
- Department of Internal Medicine, Pulmonary, Critical Care and Sleep Medicine, Yale School of Medicine, New Haven, CT 06520, USA
| | - Bharat Vaidyanathan
- Department of Immunobiology, Yale University School of Medicine, New Haven, CT 06520, USA
| | - Keith Glenn
- Department of Internal Medicine, Pulmonary, Critical Care and Sleep Medicine, Yale School of Medicine, New Haven, CT 06520, USA
| | - Shuang Yu
- Department of Immunobiology, Yale University School of Medicine, New Haven, CT 06520, USA
| | - Charles Annicelli
- Department of Immunobiology, Yale University School of Medicine, New Haven, CT 06520, USA
| | - Talia D Wiggen
- Department of Microbiology & Immunology, University of Minnesota Medical School, Minneapolis, MN 55455, USA
| | - Mitchell R Penningroth
- Department of Microbiology & Immunology, University of Minnesota Medical School, Minneapolis, MN 55455, USA
| | - Ryan C Hunter
- Department of Microbiology & Immunology, University of Minnesota Medical School, Minneapolis, MN 55455, USA
| | - Charles S Dela Cruz
- Department of Internal Medicine, Pulmonary, Critical Care and Sleep Medicine, Yale School of Medicine, New Haven, CT 06520, USA
| | - Ruslan Medzhitov
- Howard Hughes Medical Institute and Department of Immunobiology, Yale University School of Medicine, New Haven, CT 06520, USA.
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11
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Ong ZX, Kannan B, Becker DL. Exploiting transposons in the study of Staphylococcus aureus pathogenesis and virulence. Crit Rev Microbiol 2022; 49:297-317. [PMID: 35438613 DOI: 10.1080/1040841x.2022.2052794] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
The opportunistic pathogen Staphylococcus aureus has an extremely complex relationship with humans. While the bacteria can exist as a commensal in many, it can cause a wide range of diseases and infections when turned pathogenic. Its presence is a determinant of chronicity and poor prognosis in numerous diseases, and its genomic plasticity causes S. aureus antimicrobial resistance to be one of the most dire contemporary medical problems to solve. Genetic manipulation of S. aureus has led to numerous findings that are vital in the fight against its pathogenesis. The utilisation of transposon mutant libraries for the systematic inspection of the S. aureus genome led to many landmark discoveries pertaining to the bacteria's pathogenicity, antimicrobial resistance acquisition, and virulence regulation. In this review, we describe mutant libraries, and their significant contributions, from various S. aureus strains created with commonly used transposons. The general workflow for the construction of libraries will be presented, along with a discussion of the challenges of undertaking the task of large-scale library construction. As the accessibility of transposon mutant library construction, screening, and analysis increases, this genetic tool could be further exploited in the study of the S. aureus genome.
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Affiliation(s)
- Zi Xin Ong
- Lee Kong Chian School of Medicine, Nanyang Technological University, Singapore.,Skin Research Institute, Singapore.,Nanyang Institute of Technology in Health and Medicine, Interdisciplinary Graduate Programme, Nanyang Technological University, Singapore
| | - Bavani Kannan
- Lee Kong Chian School of Medicine, Nanyang Technological University, Singapore.,Skin Research Institute, Singapore
| | - David L Becker
- Lee Kong Chian School of Medicine, Nanyang Technological University, Singapore.,Skin Research Institute, Singapore
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12
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Rei Yan SL, Wakasuqui F, Du X, Groves MR, Wrenger C. Lipoic Acid Metabolism as a Potential Chemotherapeutic Target Against Plasmodium falciparum and Staphylococcus aureus. Front Chem 2021; 9:742175. [PMID: 34805091 PMCID: PMC8600131 DOI: 10.3389/fchem.2021.742175] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2021] [Accepted: 10/21/2021] [Indexed: 11/17/2022] Open
Abstract
Lipoic acid (LA) is an organic compound that plays a key role in cellular metabolism. It participates in a posttranslational modification (PTM) named lipoylation, an event that is highly conserved and that occurs in multimeric metabolic enzymes of very distinct microorganisms such as Plasmodium sp. and Staphylococcus aureus, including pyruvate dehydrogenase (PDH) and α-ketoglutarate dehydrogenase (KDH). In this mini review, we revisit the recent literature regarding LA metabolism in Plasmodium sp. and Staphylococcus aureus, by covering the lipoate ligase proteins in both microorganisms, the role of lipoate ligase proteins and insights for possible inhibitors of lipoate ligases.
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Affiliation(s)
- Sun Liu Rei Yan
- Unit for Drug Discovery, Department of Parasitology, Institute of Biomedical Sciences-ICB, University of São Paulo, São Paulo, Brazil
| | - Felipe Wakasuqui
- Unit for Drug Discovery, Department of Parasitology, Institute of Biomedical Sciences-ICB, University of São Paulo, São Paulo, Brazil
| | - Xiaochen Du
- Structural Biology in Drug Design, Department of Drug Design, Groningen Research Institute of Pharmacy, University of Groningen, Groningen, Netherlands
| | - Matthew R Groves
- Structural Biology in Drug Design, Department of Drug Design, Groningen Research Institute of Pharmacy, University of Groningen, Groningen, Netherlands
| | - Carsten Wrenger
- Unit for Drug Discovery, Department of Parasitology, Institute of Biomedical Sciences-ICB, University of São Paulo, São Paulo, Brazil
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13
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Monteith AJ, Miller JM, Maxwell CN, Chazin WJ, Skaar EP. Neutrophil extracellular traps enhance macrophage killing of bacterial pathogens. SCIENCE ADVANCES 2021; 7:eabj2101. [PMID: 34516771 PMCID: PMC8442908 DOI: 10.1126/sciadv.abj2101] [Citation(s) in RCA: 54] [Impact Index Per Article: 18.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/27/2021] [Accepted: 07/20/2021] [Indexed: 05/16/2023]
Abstract
Neutrophils and macrophages are critical to the innate immune response, but cooperative mechanisms used by these cells to combat extracellular pathogens are not well understood. This study reveals that S100A9-deficient neutrophils produce higher levels of mitochondrial superoxide in response to Staphylococcus aureus and, as a result, form neutrophil extracellular traps (suicidal NETosis). Increased suicidal NETosis does not improve neutrophil killing of S. aureus in isolation but augments macrophage killing. NET formation enhances antibacterial activity by increasing phagocytosis by macrophages and by transferring neutrophil-specific antimicrobial peptides to them. Similar results were observed in response to other phylogenetically distinct bacterial pathogens including Streptococcus pneumoniae and Pseudomonas aeruginosa, implicating this as an immune defense mechanism that broadly enhances antibacterial activity. These results demonstrate that achieving maximal bactericidal activity through NET formation requires macrophages and that accelerated and more robust suicidal NETosis makes neutrophils adept at increasing antibacterial activity, especially when A9 deficient.
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Affiliation(s)
- Andrew J. Monteith
- Department of Pathology, Microbiology, and Immunology, Vanderbilt University Medical Center, Nashville, TN, USA
| | - Jeanette M. Miller
- Department of Pathology, Microbiology, and Immunology, Vanderbilt University Medical Center, Nashville, TN, USA
| | - C. Noel Maxwell
- Department of Biochemistry, Vanderbilt University, Nashville, TN, USA
- Center for Structural Biology, Vanderbilt University, Nashville, TN, USA
| | - Walter J. Chazin
- Department of Biochemistry, Vanderbilt University, Nashville, TN, USA
- Center for Structural Biology, Vanderbilt University, Nashville, TN, USA
- Department of Chemistry, Vanderbilt University, Nashville, TN, USA
- Vanderbilt Institute for Infection, Immunology, and Inflammation, Vanderbilt University Medical Center, Nashville, TN, USA
| | - Eric P. Skaar
- Department of Pathology, Microbiology, and Immunology, Vanderbilt University Medical Center, Nashville, TN, USA
- Vanderbilt Institute for Infection, Immunology, and Inflammation, Vanderbilt University Medical Center, Nashville, TN, USA
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14
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Chen X, Teoh WP, Stock MR, Resko ZJ, Alonzo F. Branched chain fatty acid synthesis drives tissue-specific innate immune response and infection dynamics of Staphylococcus aureus. PLoS Pathog 2021; 17:e1009930. [PMID: 34496007 PMCID: PMC8452012 DOI: 10.1371/journal.ppat.1009930] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2021] [Revised: 09/20/2021] [Accepted: 08/30/2021] [Indexed: 12/13/2022] Open
Abstract
Fatty acid-derived acyl chains of phospholipids and lipoproteins are central to bacterial membrane fluidity and lipoprotein function. Though it can incorporate exogenous unsaturated fatty acids (UFA), Staphylococcus aureus synthesizes branched chain fatty acids (BCFA), not UFA, to modulate or increase membrane fluidity. However, both endogenous BCFA and exogenous UFA can be attached to bacterial lipoproteins. Furthermore, S. aureus membrane lipid content varies based upon the amount of exogenous lipid in the environment. Thus far, the relevance of acyl chain diversity within the S. aureus cell envelope is limited to the observation that attachment of UFA to lipoproteins enhances cytokine secretion by cell lines in a TLR2-dependent manner. Here, we leveraged a BCFA auxotroph of S. aureus and determined that driving UFA incorporation disrupted infection dynamics and increased cytokine production in the liver during systemic infection of mice. In contrast, infection of TLR2-deficient mice restored inflammatory cytokines and bacterial burden to wildtype levels, linking the shift in acyl chain composition toward UFA to detrimental immune activation in vivo. In in vitro studies, bacterial lipoproteins isolated from UFA-supplemented cultures were resistant to lipase-mediated ester hydrolysis and exhibited heightened TLR2-dependent innate cell activation, whereas lipoproteins with BCFA esters were completely inactivated after lipase treatment. These results suggest that de novo synthesis of BCFA reduces lipoprotein-mediated TLR2 activation and improves lipase-mediated hydrolysis making it an important determinant of innate immunity. Overall, this study highlights the potential relevance of cell envelope acyl chain repertoire in infection dynamics of bacterial pathogens.
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Affiliation(s)
- Xi Chen
- Department of Microbiology and Immunology, Loyola University Chicago–Stritch School of Medicine, Maywood, Illinois, United States of America
| | - Wei Ping Teoh
- Department of Microbiology and Immunology, Loyola University Chicago–Stritch School of Medicine, Maywood, Illinois, United States of America
| | - Madison R. Stock
- Department of Microbiology and Immunology, Loyola University Chicago–Stritch School of Medicine, Maywood, Illinois, United States of America
| | - Zachary J. Resko
- Department of Microbiology and Immunology, Loyola University Chicago–Stritch School of Medicine, Maywood, Illinois, United States of America
| | - Francis Alonzo
- Department of Microbiology and Immunology, Loyola University Chicago–Stritch School of Medicine, Maywood, Illinois, United States of America
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15
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16
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Sargison FA, Fitzgerald JR. Advances in Transposon Mutagenesis of Staphylococcus aureus: Insights into Pathogenesis and Antimicrobial Resistance. Trends Microbiol 2021; 29:282-285. [PMID: 33279382 DOI: 10.1016/j.tim.2020.11.003] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2020] [Revised: 11/03/2020] [Accepted: 11/05/2020] [Indexed: 10/22/2022]
Abstract
Our capacity to investigate the biology of the major human and animal pathogen Staphylococcus aureus has been greatly enhanced by technological advances in transposon (Tn) mutagenesis. Here we provide a perspective on how these advances can further our understanding of pathogenesis and antibiotic resistance.
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Affiliation(s)
- Fiona A Sargison
- Roslin Institute, University of Edinburgh, Easter Bush Campus, Edinburgh EH25 9RG, UK
| | - J Ross Fitzgerald
- Roslin Institute, University of Edinburgh, Easter Bush Campus, Edinburgh EH25 9RG, UK.
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17
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Bouvenot T, Dewitte A, Bennaceur N, Pradel E, Pierre F, Bontemps-Gallo S, Sebbane F. Interplay between Yersinia pestis and its flea vector in lipoate metabolism. THE ISME JOURNAL 2021; 15:1136-1149. [PMID: 33479491 PMCID: PMC8182812 DOI: 10.1038/s41396-020-00839-0] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/16/2020] [Revised: 10/22/2020] [Accepted: 11/11/2020] [Indexed: 01/29/2023]
Abstract
To thrive, vector-borne pathogens must survive in the vector's gut. How these pathogens successfully exploit this environment in time and space has not been extensively characterized. Using Yersinia pestis (the plague bacillus) and its flea vector, we developed a bioluminescence-based approach and employed it to investigate the mechanisms of pathogenesis at an unprecedented level of detail. Remarkably, lipoylation of metabolic enzymes, via the biosynthesis and salvage of lipoate, increases the Y. pestis transmission rate by fleas. Interestingly, the salvage pathway's lipoate/octanoate ligase LplA enhances the first step in lipoate biosynthesis during foregut colonization but not during midgut colonization. Lastly, Y. pestis primarily uses lipoate provided by digestive proteolysis (presumably as lipoyl peptides) rather than free lipoate in blood, which is quickly depleted by the vector. Thus, spatial and temporal factors dictate the bacterium's lipoylation strategies during an infection, and replenishment of lipoate by digestive proteolysis in the vector might constitute an Achilles' heel that is exploited by pathogens.
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Affiliation(s)
- Typhanie Bouvenot
- grid.503422.20000 0001 2242 6780Univ. Lille, Inserm, CNRS, CHU Lille, Institut Pasteur de Lille, U1019 - UMR 9017 – CIIL - Center for Infection and Immunity of Lille, F-59000 Lille, France
| | - Amélie Dewitte
- grid.503422.20000 0001 2242 6780Univ. Lille, Inserm, CNRS, CHU Lille, Institut Pasteur de Lille, U1019 - UMR 9017 – CIIL - Center for Infection and Immunity of Lille, F-59000 Lille, France
| | - Nadia Bennaceur
- grid.503422.20000 0001 2242 6780Univ. Lille, Inserm, CNRS, CHU Lille, Institut Pasteur de Lille, U1019 - UMR 9017 – CIIL - Center for Infection and Immunity of Lille, F-59000 Lille, France
| | - Elizabeth Pradel
- grid.503422.20000 0001 2242 6780Univ. Lille, Inserm, CNRS, CHU Lille, Institut Pasteur de Lille, U1019 - UMR 9017 – CIIL - Center for Infection and Immunity of Lille, F-59000 Lille, France
| | - François Pierre
- grid.503422.20000 0001 2242 6780Univ. Lille, Inserm, CNRS, CHU Lille, Institut Pasteur de Lille, U1019 - UMR 9017 – CIIL - Center for Infection and Immunity of Lille, F-59000 Lille, France
| | - Sébastien Bontemps-Gallo
- grid.503422.20000 0001 2242 6780Univ. Lille, Inserm, CNRS, CHU Lille, Institut Pasteur de Lille, U1019 - UMR 9017 – CIIL - Center for Infection and Immunity of Lille, F-59000 Lille, France
| | - Florent Sebbane
- grid.503422.20000 0001 2242 6780Univ. Lille, Inserm, CNRS, CHU Lille, Institut Pasteur de Lille, U1019 - UMR 9017 – CIIL - Center for Infection and Immunity of Lille, F-59000 Lille, France
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18
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Staphylococcus aureus adapts to the host nutritional landscape to overcome tissue-specific branched-chain fatty acid requirement. Proc Natl Acad Sci U S A 2021; 118:2022720118. [PMID: 33753501 DOI: 10.1073/pnas.2022720118] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
During infection, pathogenic microbes adapt to the nutritional milieu of the host through metabolic reprogramming and nutrient scavenging. For the bacterial pathogen Staphylococcus aureus, virulence in diverse infection sites is driven by the ability to scavenge myriad host nutrients, including lipoic acid, a cofactor required for the function of several critical metabolic enzyme complexes. S. aureus shuttles lipoic acid between these enzyme complexes via the amidotransferase, LipL. Here, we find that acquisition of lipoic acid, or its attachment via LipL to enzyme complexes required for the generation of acetyl-CoA and branched-chain fatty acids, is essential for bacteremia, yet dispensable for skin infection in mice. A lipL mutant is auxotrophic for carboxylic acid precursors required for synthesis of branched-chain fatty acids, an essential component of staphylococcal membrane lipids and the agent of membrane fluidity. However, the skin is devoid of branched-chain fatty acids. We showed that S. aureus instead scavenges host-derived unsaturated fatty acids from the skin using the secreted lipase, Geh, and the unsaturated fatty acid-binding protein, FakB2. Moreover, murine infections demonstrated the relevance of host lipid assimilation to staphylococcal survival. Altogether, these studies provide insight into an adaptive trait that bypasses de novo lipid synthesis to facilitate S. aureus persistence during superficial infection. The findings also reinforce the inherent challenges associated with targeting bacterial lipogenesis as an antibacterial strategy and support simultaneous inhibition of host fatty acid salvage during treatment.
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19
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Galli G, Saleh M. Immunometabolism of Macrophages in Bacterial Infections. Front Cell Infect Microbiol 2021; 10:607650. [PMID: 33585278 PMCID: PMC7879570 DOI: 10.3389/fcimb.2020.607650] [Citation(s) in RCA: 27] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2020] [Accepted: 12/14/2020] [Indexed: 12/18/2022] Open
Abstract
Macrophages are important effectors of tissue homeostasis, inflammation and host defense. They are equipped with an arsenal of pattern recognition receptors (PRRs) necessary to sense microbial- or danger-associated molecular patterns (MAMPs/DAMPs) and elicit rapid energetically costly innate immunity responses to protect the organism. The interaction between cellular metabolism and macrophage innate immunity is however not limited to answering the cell’s energy demands. Mounting evidence now indicate that in response to bacterial sensing, macrophages undergo metabolic adaptations that contribute to the induction of innate immunity signaling and/or macrophage polarization. In particular, intermediates of the glycolysis pathway, the Tricarboxylic Acid (TCA) cycle, mitochondrial respiration, amino acid and lipid metabolism directly interact with and modulate macrophage effectors at the epigenetic, transcriptional and post-translational levels. Interestingly, some intracellular bacterial pathogens usurp macrophage metabolic pathways to attenuate anti-bacterial defenses. In this review, we highlight recent evidence describing such host-bacterial immunometabolic interactions.
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Affiliation(s)
- Gaël Galli
- University of Bordeaux, CNRS, ImmunoConcEpT, UMR 5164, Bordeaux, France.,Department of Internal Medicine, CHU Bordeaux, Haut Leveque Hospital, Pessac, France
| | - Maya Saleh
- University of Bordeaux, CNRS, ImmunoConcEpT, UMR 5164, Bordeaux, France.,Department of Medicine, McGill University, Montreal, QC, Canada
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20
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Pidwill GR, Gibson JF, Cole J, Renshaw SA, Foster SJ. The Role of Macrophages in Staphylococcus aureus Infection. Front Immunol 2021; 11:620339. [PMID: 33542723 PMCID: PMC7850989 DOI: 10.3389/fimmu.2020.620339] [Citation(s) in RCA: 119] [Impact Index Per Article: 39.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2020] [Accepted: 12/02/2020] [Indexed: 12/23/2022] Open
Abstract
Staphylococcus aureus is a member of the human commensal microflora that exists, apparently benignly, at multiple sites on the host. However, as an opportunist pathogen it can also cause a range of serious diseases. This requires an ability to circumvent the innate immune system to establish an infection. Professional phagocytes, primarily macrophages and neutrophils, are key innate immune cells which interact with S. aureus, acting as gatekeepers to contain and resolve infection. Recent studies have highlighted the important roles of macrophages during S. aureus infections, using a wide array of killing mechanisms. In defense, S. aureus has evolved multiple strategies to survive within, manipulate and escape from macrophages, allowing them to not only subvert but also exploit this key element of our immune system. Macrophage-S. aureus interactions are multifaceted and have direct roles in infection outcome. In depth understanding of these host-pathogen interactions may be useful for future therapeutic developments. This review examines macrophage interactions with S. aureus throughout all stages of infection, with special emphasis on mechanisms that determine infection outcome.
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Affiliation(s)
- Grace R Pidwill
- Department of Molecular Biology and Biotechnology, University of Sheffield, Sheffield, United Kingdom.,Florey Institute, University of Sheffield, Sheffield, United Kingdom
| | - Josie F Gibson
- Department of Molecular Biology and Biotechnology, University of Sheffield, Sheffield, United Kingdom.,Florey Institute, University of Sheffield, Sheffield, United Kingdom.,The Bateson Centre, University of Sheffield, Sheffield, United Kingdom
| | - Joby Cole
- Florey Institute, University of Sheffield, Sheffield, United Kingdom.,Department of Infection, Immunity and Cardiovascular Disease, Medical School, University of Sheffield, Sheffield, United Kingdom
| | - Stephen A Renshaw
- Florey Institute, University of Sheffield, Sheffield, United Kingdom.,The Bateson Centre, University of Sheffield, Sheffield, United Kingdom.,Department of Infection, Immunity and Cardiovascular Disease, Medical School, University of Sheffield, Sheffield, United Kingdom
| | - Simon J Foster
- Department of Molecular Biology and Biotechnology, University of Sheffield, Sheffield, United Kingdom.,Florey Institute, University of Sheffield, Sheffield, United Kingdom
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21
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Dramatic Changes in Oligomerization Property Caused by Single Residue Deletion in Staphylococcus aureus Enolase. Mol Biotechnol 2021; 63:125-139. [PMID: 33385272 DOI: 10.1007/s12033-020-00291-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/11/2020] [Indexed: 10/22/2022]
Abstract
Studies were conducted to understand the role of C-terminal lysine residues in the catalytic activity, structural stability and oligomeric properties of Staphylococcus aureus enolase. Interestingly, the S. aureus enolase, in solution, shows its presence as a stable dimer as well as the catalytically active fragile octamer. Compared to the hexa-histidine tagged S. aureus enolase (rSaeno), the deletion mutant showed the negligible difference in Km, but approximately 20-25% reduction in maximum reaction velocity (Vmax) and 2% reduction in turnover number were observed. These kinetic parameters indicate that K-434Δ deletion mutation does not drastically compromise the enzyme efficiency. The secondary structure and the octameric conformation of both the rSaeno and the K-434Δ mutant are very much stable between pH ranging from 6 to 9, temperatures ranging from 20 to 40 °C and in the presence of divalent metal ions Mg2+, Zn2+ and Mn2+. Under these conditions, the recombinant enzyme and the mutant are also catalytically very active. Intrinsic tryptophan fluorescence (320-380 nm) and CD spectral (195-260 nm) analysis revealed that the secondary structure and the surface architecture of the proteins are not majorly altered by the mutation. But, a significant correlation was observed between the time-dependent decrease in the catalytic activity and the oligomeric stability of rSaeno and K-434Δ mutant. The C-terminal lysine residues in the inter-dimer groove aid in folding and oligomerization of S. aureus enolase.
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22
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Behmoaras J. The versatile biochemistry of iron in macrophage effector functions. FEBS J 2020; 288:6972-6989. [PMID: 33354925 DOI: 10.1111/febs.15682] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2020] [Revised: 12/16/2020] [Accepted: 12/21/2020] [Indexed: 01/01/2023]
Abstract
Macrophages are mononuclear phagocytes with remarkable polarization ability that allow them to have tissue-specific functions during development, homeostasis, inflammatory and infectious disease. One particular trophic factor in the tissue environment is iron, which is intimately linked to macrophage effector functions. Macrophages have a well-described role in the control of systemic iron levels, but their activation state is also depending on iron-containing proteins/enzymes. Haemoproteins, dioxygenases and iron-sulphur (Fe-S) enzymes are iron-binding proteins that have bactericidal, metabolic and epigenetic-related functions, essential to shape the context-dependent macrophage polarization. In this review, I describe mainly pro-inflammatory macrophage polarization focussing on the role of iron biochemistry in selected haemoproteins and Fe-S enzymes. I show how iron, as part of haem or Fe-S clusters, participates in the cellular control of pro-inflammatory redox reactions in parallel with its role as enzymatic cofactor. I highlight a possible coordinated regulation of haemoproteins and Fe-S enzymes during classical macrophage activation. Finally, I describe tryptophan and α-ketoglutarate metabolism as two essential effector pathways in macrophages that use diverse iron biochemistry at different enzymatic steps. Through these pathways, I show how iron participates in the regulation of essential metabolites that shape macrophage function.
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23
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Hemmadi V, Biswas M. An overview of moonlighting proteins in Staphylococcus aureus infection. Arch Microbiol 2020; 203:481-498. [PMID: 33048189 PMCID: PMC7551524 DOI: 10.1007/s00203-020-02071-y] [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: 07/09/2020] [Revised: 09/29/2020] [Accepted: 10/01/2020] [Indexed: 01/01/2023]
Abstract
Staphylococcus aureus is responsible for numerous instances of superficial, toxin-mediated, and invasive infections. The emergence of methicillin-resistant (MRSA), as well as vancomycin-resistant (VRSA) strains of S. aureus, poses a massive threat to human health. The tenacity of S. aureus to acquire resistance against numerous antibiotics in a very short duration makes the effort towards developing new antibiotics almost futile. S. aureus owes its destructive pathogenicity to the plethora of virulent factors it produces among which a majority of them are moonlighting proteins. Moonlighting proteins are the multifunctional proteins in which a single protein, with different oligomeric conformations, perform multiple independent functions in different cell compartments. Peculiarly, proteins involved in key ancestral functions and metabolic pathways typically exhibit moonlighting functions. Pathogens mainly employ those proteins as virulent factors which exhibit high structural conservation towards their host counterparts. Consequentially, the host immune system counteracts these invading bacterial virulent factors with minimal protective action. Additionally, many moonlighting proteins also play multiple roles in various stages of pathogenicity while augmenting the virulence of the bacterium. This has necessitated elaborative studies to be conducted on moonlighting proteins of S. aureus that can serve as drug targets. This review is a small effort towards understanding the role of various moonlighting proteins in the pathogenicity of S. aureus.
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Affiliation(s)
- Vijay Hemmadi
- Department of Biological Sciences, Birla Institute of Technology and Science, BITS-Pilani, K. K. Birla Goa Campus, NH17B, Zuarinagar, Goa, 403726, India
| | - Malabika Biswas
- Department of Biological Sciences, Birla Institute of Technology and Science, BITS-Pilani, K. K. Birla Goa Campus, NH17B, Zuarinagar, Goa, 403726, India.
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24
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Leseigneur C, Lê-Bury P, Pizarro-Cerdá J, Dussurget O. Emerging Evasion Mechanisms of Macrophage Defenses by Pathogenic Bacteria. Front Cell Infect Microbiol 2020; 10:577559. [PMID: 33102257 PMCID: PMC7545029 DOI: 10.3389/fcimb.2020.577559] [Citation(s) in RCA: 25] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2020] [Accepted: 08/26/2020] [Indexed: 12/22/2022] Open
Abstract
Macrophages participate to the first line of defense against infectious agents. Microbial pathogens evolved sophisticated mechanisms to escape macrophage killing. Here, we review recent discoveries and emerging concepts on bacterial molecular strategies to subvert macrophage immune responses. We focus on the expanding number of fascinating subversive tools developed by Listeria monocytogenes, Staphylococcus aureus, and pathogenic Yersinia spp., illustrating diversity and commonality in mechanisms used by microorganisms with different pathogenic lifestyles.
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Affiliation(s)
- Clarisse Leseigneur
- Unité de Recherche Yersinia, Institut Pasteur, Paris, France.,Université de Paris, Sorbonne Paris Cité, Paris, France
| | - Pierre Lê-Bury
- Unité de Recherche Yersinia, Institut Pasteur, Paris, France.,Université de Paris, Sorbonne Paris Cité, Paris, France
| | - Javier Pizarro-Cerdá
- Unité de Recherche Yersinia, Institut Pasteur, Paris, France.,National Reference Laboratory Plague & Other Yersiniosis, Institut Pasteur, Paris, France.,WHO Collaborative Research & Reference Centre for Yersinia, Institut Pasteur, Paris, France
| | - Olivier Dussurget
- Unité de Recherche Yersinia, Institut Pasteur, Paris, France.,Université de Paris, Sorbonne Paris Cité, Paris, France
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25
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Abstract
Medical device-associated biofilm infections are a therapeutic challenge based on their antibiotic tolerance and ability to evade immune-mediated clearance. The virulence determinants responsible for bacterial biofilm to induce a maladaptive immune response remain largely unknown. This study identified a critical role for S. aureus ATP synthase in influencing the host immune response to biofilm infection. An S. aureus ATP synthase alpha subunit mutant (ΔatpA) elicited heightened proinflammatory cytokine production by leukocytes in vitro and in vivo, which coincided with improved biofilm clearance in a mouse model of prosthetic joint infection. The ability of S. aureus ΔatpA to augment host proinflammatory responses was cell lysis-dependent, as inhibition of bacterial lysis by polyanethole sodium sulfanate or a ΔatpAΔatl biofilm did not elicit heightened cytokine production. These studies reveal a critical role for AtpA in shaping the host immune response to S. aureus biofilm. Staphylococcus aureus is a major cause of prosthetic joint infection (PJI), which is characterized by biofilm formation. S. aureus biofilm skews the host immune response toward an anti-inflammatory profile by the increased recruitment of myeloid-derived suppressor cells (MDSCs) that attenuate macrophage proinflammatory activity, leading to chronic infection. A screen of the Nebraska Transposon Mutant Library identified several hits in the ATP synthase operon that elicited a heightened inflammatory response in macrophages and MDSCs, including atpA, which encodes the alpha subunit of ATP synthase. An atpA transposon mutant (ΔatpA) had altered growth kinetics under both planktonic and biofilm conditions, along with a diffuse biofilm architecture that was permissive for leukocyte infiltration, as observed by confocal laser scanning microscopy. Coculture of MDSCs and macrophages with ΔatpA biofilm elicited significant increases in the proinflammatory cytokines interleukin 12p70 (IL-12p70), tumor necrosis factor alpha (TNF-α), and IL-6. This was attributed to increased leukocyte survival resulting from less toxin and protease production by ΔatpA biofilm as determined by liquid chromatography with tandem mass spectrometry (LC-MS/MS). The enhanced inflammatory response elicited by ΔatpA biofilm was cell lysis-dependent since it was negated by polyanethole sodium sulfanate treatment or deletion of the major autolysin, Atl. In a mouse model of PJI, ΔatpA-infected mice had decreased MDSCs concomitant with increased monocyte/macrophage infiltrates and proinflammatory cytokine production, which resulted in biofilm clearance. These studies identify S. aureus ATP synthase as an important factor in influencing the immune response during biofilm-associated infection and bacterial persistence.
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Lipoprotein N-Acylation in Staphylococcus aureus Is Catalyzed by a Two-Component Acyl Transferase System. mBio 2020; 11:mBio.01619-20. [PMID: 32723923 PMCID: PMC7387801 DOI: 10.1128/mbio.01619-20] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Although it has long been known that S. aureus forms triacylated Lpps, a lack of homologs to known N-acylation genes found in Gram-negative bacteria has until now precluded identification of the genes responsible for this Lpp modification. Here, we demonstrate N-terminal Lpp acylation and chemotype conversion to the tri-acylated state is directed by a unique acyl transferase system encoded by two noncontiguous staphylococci genes (lnsAB). Since triacylated Lpps stimulate TLR2 more weakly than their diacylated counterparts, Lpp N-acylation is an important TLR2 immunoevasion factor for determining tolerance or nontolerance in niches such as in the skin microbiota. The discovery of the LnsAB system expands the known diversity of Lpp biosynthesis pathways and acyl transfer biochemistry in bacteria, advances our understanding of Lpp structural heterogeneity, and helps differentiate commensal and noncommensal microbiota. Bacterial lipoproteins (Lpps) are a class of membrane-associated proteins universally distributed among all bacteria. A characteristic N-terminal cysteine residue that is variably acylated anchors C-terminal globular domains to the extracellular surface, where they serve numerous roles, including in the capture and transport of essential nutrients. Lpps are also ligands for the Toll-like receptor 2 (TLR2) family, a key component of the innate immune system tasked with bacterial recognition. While Lpp function is conserved in all prokaryotes, structural heterogeneity in the N-terminal acylation state is widespread among Firmicutes and can differ between otherwise closely related species. In this study, we identify a novel two-gene system that directs the synthesis of N-acylated Lpps in the commensal and opportunistic pathogen subset of staphylococci. The two genes, which we have named the lipoprotein N-acylation transferase system (Lns), bear no resemblance to previously characterized N-terminal Lpp tailoring enzymes. LnsA (SAOUHSC_00822) is an NlpC/P60 superfamily enzyme, whereas LnsB (SAOHSC_02761) has remote homology to the CAAX protease and bacteriocin-processing enzyme (CPBP) family. Both LnsA and LnsB are together necessary and alone sufficient for N-acylation in Staphylococcus aureus and convert the Lpp chemotype from diacyl to triacyl when heterologously expressed in Listeria monocytogenes. Acquisition of lnsAB decreases TLR2-mediated detection of S. aureus by nearly 10-fold and shifts the activated TLR2 complex from TLR2/6 to TLR2/1. LnsAB thus has a dual role in attenuating TLR2 signaling in addition to a broader role in bacterial cell envelope physiology.
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Niche specialization and spread of Staphylococcus capitis involved in neonatal sepsis. Nat Microbiol 2020; 5:735-745. [PMID: 32341568 DOI: 10.1038/s41564-020-0676-2] [Citation(s) in RCA: 33] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2019] [Accepted: 01/28/2020] [Indexed: 12/14/2022]
Abstract
The multidrug-resistant Staphylococcus capitis NRCS-A clone is responsible for sepsis in preterm infants in neonatal intensive care units (NICUs) worldwide. Here, to retrace the spread of this clone and to identify drivers of its specific success, we investigated a representative collection of 250 S. capitis isolates from adults and newborns. Bayesian analyses confirmed the spread of the NRCS-A clone and enabled us to date its emergence in the late 1960s and its expansion during the 1980s, coinciding with the establishment of NICUs and the increasing use of vancomycin in these units, respectively. This dynamic was accompanied by the acquisition of mutations in antimicrobial resistance- and bacteriocin-encoding genes. Furthermore, combined statistical tools and a genome-wide association study convergently point to vancomycin resistance as a major driver of NRCS-A success. We also identified another S. capitis subclade (alpha clade) that emerged independently, showing parallel evolution towards NICU specialization and non-susceptibility to vancomycin, indicating convergent evolution in NICU-associated pathogens. These findings illustrate how the broad use of antibiotics can repeatedly lead initially commensal drug-susceptible bacteria to evolve into multidrug-resistant clones that are able to successfully spread worldwide and become pathogenic for highly vulnerable patients.
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Multitasking Actors of Staphylococcus aureus Metabolism and Virulence. Trends Microbiol 2020; 28:6-9. [DOI: 10.1016/j.tim.2019.10.013] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2019] [Revised: 10/23/2019] [Accepted: 10/24/2019] [Indexed: 01/10/2023]
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Dynamic Relay of Protein-Bound Lipoic Acid in Staphylococcus aureus. J Bacteriol 2019; 201:JB.00446-19. [PMID: 31451544 DOI: 10.1128/jb.00446-19] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2019] [Accepted: 08/21/2019] [Indexed: 12/19/2022] Open
Abstract
Staphylococcus aureus competes for myriad essential nutrients during host infection. One of these nutrients is the organosulfur compound lipoic acid, a cofactor required for the activity of several metabolic enzyme complexes. In S. aureus, these include the E2 subunits of three α-ketoacid dehydrogenases and two H proteins, GcvH of the glycine cleavage system and its paralog, GcvH-L. We previously determined that the S. aureus amidotransferase LipL is required for lipoylation of the E2 subunits of pyruvate dehydrogenase (PDH) and branched-chain 2-oxoacid dehydrogenase (BCODH) complexes. The results from this study, coupled with those from Bacillus subtilis, suggested that LipL catalyzes lipoyl transfer from H proteins to E2 subunits. However, to date, the range of LipL targets, the extent of LipL-dependent lipoic acid shuttling between lipoyl domain-containing proteins, and the importance of lipoyl relay in pathogenesis remain unknown. Here, we demonstrate that LipL uses both lipoyl-H proteins as the substrates for lipoyl transfer to all E2 subunits. Moreover, LipL facilitates lipoyl relay between E2 subunits and between H proteins, a property that potentially constitutes an adaptive response to nutrient scarcity in the host, as LipL is required for virulence during infection. Together, these observations support a role for LipL in facilitating flexible lipoyl relay between proteins and highlight the complexity of protein lipoylation in S. aureus IMPORTANCE Protein lipoylation is a posttranslational modification that is evolutionarily conserved from bacteria to humans. Lipoic acid modifications are found on five proteins in S. aureus, four of which are components of major metabolic enzymes. In some bacteria, the amidotransferase LipL is critical for the attachment of lipoic acid to these proteins, and yet it is unclear to what extent LipL facilitates the transfer of this cofactor. We find that S. aureus LipL flexibly shuttles lipoic acid among metabolic enzyme subunits, alluding to a dynamic redistribution mechanism within the bacterial cell. This discovery exemplifies a potential means by which bacteria optimize the use of scarce nutrients when resources are limited.
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Talley S, Kalinina O, Winek M, Paik W, Cannon AR, Alonzo F, Choudhry MA, Knight KL, Campbell EM. A Caspase-1 Biosensor to Monitor the Progression of Inflammation In Vivo. THE JOURNAL OF IMMUNOLOGY 2019; 203:2497-2507. [DOI: 10.4049/jimmunol.1900619] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/30/2019] [Accepted: 08/21/2019] [Indexed: 12/22/2022]
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Staphylococcus aureus Lipoic Acid Synthesis Limits Macrophage Reactive Oxygen and Nitrogen Species Production To Promote Survival during Infection. Infect Immun 2019; 87:IAI.00344-19. [PMID: 31308080 DOI: 10.1128/iai.00344-19] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2019] [Accepted: 07/05/2019] [Indexed: 01/29/2023] Open
Abstract
Macrophages are critical mediators of innate immunity and must be overcome for bacterial pathogens to cause disease. The Gram-positive bacterium Staphylococcus aureus produces virulence factors that impede macrophages and other immune cells. We previously determined that production of the metabolic cofactor lipoic acid by the lipoic acid synthetase, LipA, blunts macrophage activation. A ΔlipA mutant was attenuated during infection and was more readily cleared from the host. We hypothesized that bacterial lipoic acid synthesis perturbs macrophage antimicrobial functions and therefore hinders the clearance of S. aureus Here, we found that enhanced innate immune cell activation after infection with a ΔlipA mutant was central to attenuation in vivo, whereas a growth defect imparted by the lipA mutation made a negligible contribution to overall clearance. Macrophages recruited to the site of infection with the ΔlipA mutant produced larger amounts of bactericidal reactive oxygen species (ROS) and reactive nitrogen species (RNS) than those recruited to the site of infection with the wild-type strain or the mutant strain complemented with lipA ROS derived from the NADPH phagocyte oxidase complex and RNS derived from the inducible nitric oxide synthetase, but not mitochondrial ROS, were critical for the restriction of bacterial growth under these conditions. Despite enhanced antimicrobial immunity upon primary infection with the ΔlipA mutant, we found that the host failed to mount an improved recall response to secondary infection. Our data suggest that lipoic acid synthesis in S. aureus promotes bacterial persistence during infection through limitation of ROS and RNS generation by macrophages. Broadly, this work furthers our understanding of the intersections between bacterial metabolism and immune responses to infection.
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Rasetto NB, Lavatelli A, Martin N, Mansilla MC. Unravelling the lipoyl-relay of exogenous lipoate utilization in Bacillus subtilis. Mol Microbiol 2019; 112:302-316. [PMID: 31066113 DOI: 10.1111/mmi.14271] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/02/2019] [Indexed: 11/29/2022]
Abstract
Lipoate is an essential cofactor for key enzymes of oxidative and one-carbon metabolism. It is covalently attached to E2 subunits of dehydrogenase complexes and GcvH, the H subunit of the glycine cleavage system. Bacillus subtilis possess two protein lipoylation pathways: biosynthesis and scavenging. The former requires octanoylation of GcvH, insertion of sulfur atoms and amidotransfer of the lipoate to E2s, catalyzed by LipL. Lipoate scavenging is mediated by a lipoyl protein ligase (LplJ) that catalyzes a classical two-step ATP-dependent reaction. Although these pathways were thought to be redundant, a ∆lipL mutant, in which the endogenous lipoylation pathway of E2 subunits is blocked, showed growth defects in minimal media even when supplemented with lipoate and despite the presence of a functional LplJ. In this study, we demonstrate that LipL is essential to modify E2 subunits of branched chain ketoacid and pyruvate dehydrogenases during lipoate scavenging. The crucial role of LipL during lipoate utilization relies on the strict substrate specificity of LplJ, determined by charge complementarity between the ligase and the lipoylable subunits. This new lipoyl-relay required for lipoate scavenging highlights the relevance of the amidotransferase as a valid target for the design of new antimicrobial agents among Gram-positive pathogens.
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Affiliation(s)
- Natalí B Rasetto
- Instituto de Biología Molecular y Celular de Rosario (IBR), Consejo Nacional de Investigaciones Científicas y Técnicas, and Departamento de Microbiología Facultad de Ciencias Bioquímicas y Farmacéuticas, Universidad Nacional de Rosario. Ocampo y Esmeralda, Predio CONICET, Rosario, S2000FHQ, Argentina
| | - Antonela Lavatelli
- Instituto de Biología Molecular y Celular de Rosario (IBR), Consejo Nacional de Investigaciones Científicas y Técnicas, and Departamento de Microbiología Facultad de Ciencias Bioquímicas y Farmacéuticas, Universidad Nacional de Rosario. Ocampo y Esmeralda, Predio CONICET, Rosario, S2000FHQ, Argentina
| | - Natalia Martin
- Department of Microbiology and Molecular Genetics, Michigan State University, East Lansing, Michigan, 48824, USA
| | - María Cecilia Mansilla
- Instituto de Biología Molecular y Celular de Rosario (IBR), Consejo Nacional de Investigaciones Científicas y Técnicas, and Departamento de Microbiología Facultad de Ciencias Bioquímicas y Farmacéuticas, Universidad Nacional de Rosario. Ocampo y Esmeralda, Predio CONICET, Rosario, S2000FHQ, Argentina
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Control of Staphylococcus aureus Quorum Sensing by a Membrane-Embedded Peptidase. Infect Immun 2019; 87:IAI.00019-19. [PMID: 30833334 DOI: 10.1128/iai.00019-19] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2019] [Accepted: 02/23/2019] [Indexed: 02/08/2023] Open
Abstract
Gram-positive bacteria process and release small peptides, or pheromones, that act as signals for the induction of adaptive traits, including those involved in pathogenesis. One class of small signaling pheromones is the cyclic autoinducing peptides (AIPs), which regulate expression of genes that orchestrate virulence and persistence in a range of microbes, including staphylococci, listeriae, clostridia, and enterococci. In a genetic screen for Staphylococcus aureus secreted virulence factors, we identified an S. aureus mutant containing an insertion in the gene SAUSA300_1984 (mroQ), which encodes a putative membrane-embedded metalloprotease. A ΔmroQ mutant exhibited impaired induction of Toll-like receptor 2-dependent inflammatory responses from macrophages but elicited greater production of the inflammatory cytokine interleukin-1β and was attenuated in a murine skin and soft tissue infection model. The ΔmroQ mutant phenocopies an S. aureus mutant containing a deletion of the accessory gene regulatory system (Agr), wherein both strains have significantly reduced production of secreted toxins and virulence factors but increased surface protein A abundance. The Agr system controls virulence factor gene expression in S. aureus by sensing the accumulation of AIP via the histidine kinase AgrC and the response regulator AgrA. We provide evidence to suggest that MroQ acts within the Agr pathway to facilitate the optimal processing or export of AIP for signal amplification through AgrC/A and induction of virulence factor gene expression. Mutation of MroQ active-site residues significantly reduces AIP signaling and attenuates virulence. Altogether, this work identifies a new component of the Agr quorum-sensing circuit that is critical for the production of S. aureus virulence factors.
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Bacterial lipolysis of immune-activating ligands promotes evasion of innate defenses. Proc Natl Acad Sci U S A 2019; 116:3764-3773. [PMID: 30755523 DOI: 10.1073/pnas.1817248116] [Citation(s) in RCA: 49] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Commensal and pathogenic bacteria hydrolyze host lipid substrates with secreted lipases and phospholipases for nutrient acquisition, colonization, and infection. Bacterial lipase activity on mammalian lipids and phospholipids can promote release of free fatty acids from lipid stores, detoxify antimicrobial lipids, and facilitate membrane dissolution. The gram-positive bacterium Staphylococcus aureus secretes at least two lipases, Sal1 and glycerol ester hydrolase (Geh), with specificities for short- and long-chain fatty acids, respectively, each with roles in the hydrolysis of environmental lipids. In a recent study from our group, we made the unexpected observation that Geh released by S. aureus inhibits activation of innate immune cells. Herein, we investigated the possibility that S. aureus lipases interface with the host immune system to blunt innate immune recognition of the microbe. We found that the Geh lipase, but not other S. aureus lipases, prevents activation of innate cells in culture. Mutation of geh leads to enhancement of proinflammatory cytokine production during infection, increased innate immune activity, and improved clearance of the bacterium in infected tissue. These in vitro and in vivo effects on innate immunity were not due to direct functions of the lipase on mammalian cells, but rather a result of inactivation of S. aureus lipoproteins, a major pathogen-associated molecular pattern (PAMP) of extracellular gram-positive bacteria, via ester hydrolysis. Altogether, these studies provide insight into an adaptive trait that masks microbial recognition by innate immune cells through targeted inactivation of a broadly conserved PAMP.
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Ebner P, Götz F. Bacterial Excretion of Cytoplasmic Proteins (ECP): Occurrence, Mechanism, and Function. Trends Microbiol 2019; 27:176-187. [DOI: 10.1016/j.tim.2018.10.006] [Citation(s) in RCA: 32] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2018] [Revised: 09/11/2018] [Accepted: 10/16/2018] [Indexed: 12/28/2022]
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36
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Probiotic Exopolysaccharide Protects against Systemic Staphylococcus aureus Infection, Inducing Dual-Functioning Macrophages That Restrict Bacterial Growth and Limit Inflammation. Infect Immun 2018; 87:IAI.00791-18. [PMID: 30396894 DOI: 10.1128/iai.00791-18] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2018] [Accepted: 10/26/2018] [Indexed: 02/07/2023] Open
Abstract
Staphylococcus aureus causes severe systemic infection with high mortality rates. We previously identified exopolysaccharide (EPS) from a probiotic, Bacillus subtilis, that induces anti-inflammatory macrophages with an M2 phenotype and protects mice from Citrobacter rodentium-induced colitis. We tested if EPS could protect from systemic infection induced by S. aureus and found that EPS-treated mice had enhanced survival as well as reduced weight loss, systemic inflammation, and bacterial burden. While macrophages from EPS-treated mice display an M2 phenotype, they also restrict growth of internalized S. aureus through reactive oxygen species (ROS), reminiscent of proinflammatory phagocytes. These EPS-induced macrophages also limit T cell activation by S. aureus superantigens, and EPS abrogates systemic induction of gamma interferon after infection. We conclude that B. subtilis EPS is an immunomodulatory agent that induces hybrid macrophages that bolster antibacterial immunity and simultaneously limit inflammation, reducing disease burden and promoting host survival.
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Golias T, Kery M, Radenkovic S, Papandreou I. Microenvironmental control of glucose metabolism in tumors by regulation of pyruvate dehydrogenase. Int J Cancer 2018; 144:674-686. [PMID: 30121950 DOI: 10.1002/ijc.31812] [Citation(s) in RCA: 42] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2018] [Revised: 07/13/2018] [Accepted: 08/06/2018] [Indexed: 12/13/2022]
Abstract
During malignant progression cancer cells undergo a series of changes, which promote their survival, invasiveness and metastatic process. One of them is a change in glucose metabolism. Unlike normal cells, which mostly rely on the tricarboxylic acid cycle (TCA), many cancer types rely on glycolysis. Pyruvate dehydrogenase complex (PDC) is the gatekeeper enzyme between these two pathways and is responsible for converting pyruvate to acetyl-CoA, which can then be processed further in the TCA cycle. Its activity is regulated by PDP (pyruvate dehydrogenase phosphatases) and PDHK (pyruvate dehydrogenase kinases). Pyruvate dehydrogenase kinase exists in 4 tissue specific isoforms (PDHK1-4), the activities of which are regulated by different factors, including hormones, hypoxia and nutrients. PDHK1 and PDHK3 are active in the hypoxic tumor microenvironment and inhibit PDC, resulting in a decrease of mitochondrial function and activation of the glycolytic pathway. High PDHK1/3 expression is associated with worse prognosis in patients, which makes them a promising target for cancer therapy. However, a better understanding of PDC's enzymatic regulation in vivo and of the mechanisms of PDHK-mediated malignant progression is necessary for the design of better PDHK inhibitors and the selection of patients most likely to benefit from such inhibitors.
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Affiliation(s)
- Tereza Golias
- Institute of Virology, Biomedical Research Center, Slovak Academy of Sciences, Bratislava, Slovak Republic
| | - Martin Kery
- Institute of Virology, Biomedical Research Center, Slovak Academy of Sciences, Bratislava, Slovak Republic
| | - Silvia Radenkovic
- Institute of Virology, Biomedical Research Center, Slovak Academy of Sciences, Bratislava, Slovak Republic
| | - Ioanna Papandreou
- Department of Radiation Oncology, The Ohio State University Comprehensive Cancer Center and Wexner Medical Center, Columbus, OH
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Guanine Limitation Results in CodY-Dependent and -Independent Alteration of Staphylococcus aureus Physiology and Gene Expression. J Bacteriol 2018; 200:JB.00136-18. [PMID: 29712876 DOI: 10.1128/jb.00136-18] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2018] [Accepted: 04/25/2018] [Indexed: 02/03/2023] Open
Abstract
In Staphylococcus aureus, the global transcriptional regulator CodY modulates the expression of hundreds of genes in response to the availability of GTP and the branched-chain amino acids isoleucine, leucine, and valine (ILV). CodY DNA-binding activity is high when GTP and ILV are abundant. When GTP and ILV are limited, CodY's affinity for DNA drops, altering expression of CodY-regulated targets. In this work, we investigated the impact of guanine nucleotides (GNs) on S. aureus physiology and CodY activity by constructing a guaA null mutant (ΔguaA strain). De novo biosynthesis of guanine monophosphate is abolished due to the guaA mutation; thus, the mutant cells require exogenous guanosine for growth. We also found that CodY activity was reduced when we knocked out guaA, activating the Agr two-component system and increasing secreted protease activity. Notably, in a rich, complex medium, we detected an increase in alternative sigma factor B activity in the ΔguaA mutant, which results in a 5-fold increase in production of the antioxidant pigment staphyloxanthin. Under biologically relevant flow conditions, ΔguaA cells failed to form robust biofilms when limited for guanine or guanosine. Transcriptome sequencing (RNA-Seq) analysis of the S. aureus transcriptome during growth in guanosine-limited chemostats revealed substantial CodY-dependent and -independent alterations of gene expression profiles. Importantly, these changes increase production of proteases and δ-toxin, suggesting that S. aureus exhibits a more invasive lifestyle when limited for guanosine. Further, gene products upregulated under GN limitation, including those necessary for lipoic acid biosynthesis and sugar transport, may prove to be useful drug targets for treating Gram-positive infections.IMPORTANCE Staphylococcus aureus infections impose a serious economic burden on health care facilities and patients because of the emergence of strains resistant to last-line antibiotics. Understanding the physiological processes governing fitness and virulence of S. aureus in response to environmental cues is critical for developing efficient diagnostics and treatments. De novo purine biosynthesis is essential for both fitness and virulence in S. aureus since inhibiting production cripples S. aureus's ability to cause infection. Here, we corroborate these findings and show that blocking guanine nucleotide synthesis severely affects S. aureus fitness by altering metabolic and virulence gene expression. Characterizing pathways and gene products upregulated in response to guanine limitation can aid in the development of novel adjuvant strategies to combat S. aureus infections.
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Laczkovich I, Teoh WP, Flury S, Grayczyk JP, Zorzoli A, Alonzo F. Increased flexibility in the use of exogenous lipoic acid by Staphylococcus aureus. Mol Microbiol 2018; 109:150-168. [PMID: 29660187 DOI: 10.1111/mmi.13970] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/11/2018] [Indexed: 02/06/2023]
Abstract
Lipoic acid is a cofactor required for intermediary metabolism that is either synthesized de novo or acquired from environmental sources. The bacterial pathogen Staphylococcus aureus encodes enzymes required for de novo biosynthesis, but also encodes two ligases, LplA1 and LplA2, that are sufficient for lipoic acid salvage during infection. S. aureus also encodes two H proteins, GcvH of the glycine cleavage system and the homologous GcvH-L encoded in an operon with LplA2. GcvH is a recognized conduit for lipoyl transfer to α-ketoacid dehydrogenase E2 subunits, while the function of GcvH-L remains unclear. The potential to produce two ligases and two H proteins is an unusual characteristic of S. aureus that is unlike most other Gram positive Firmicutes and might allude to an expanded pathway of lipoic acid acquisition in this microorganism. Here, we demonstrate that LplA1 and LplA2 facilitate lipoic acid salvage by differentially targeting lipoyl domain-containing proteins; LplA1 targets H proteins and LplA2 targets α-ketoacid dehydrogenase E2 subunits. Furthermore, GcvH and GcvH-L both facilitate lipoyl relay to E2 subunits. Altogether, these studies identify an expanded mode of lipoic acid salvage used by S. aureus and more broadly underscore the importance of bacterial adaptations when faced with nutritional limitation.
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Affiliation(s)
- Irina Laczkovich
- Department of Microbiology and Immunology, Loyola University Chicago - Stritch School of Medicine, 2160 S. First Avenue, Maywood, IL, 60153, USA
| | - Wei Ping Teoh
- Department of Microbiology and Immunology, Loyola University Chicago - Stritch School of Medicine, 2160 S. First Avenue, Maywood, IL, 60153, USA
| | - Sarah Flury
- Department of Microbiology and Immunology, Loyola University Chicago - Stritch School of Medicine, 2160 S. First Avenue, Maywood, IL, 60153, USA
| | - James P Grayczyk
- Department of Microbiology and Immunology, Loyola University Chicago - Stritch School of Medicine, 2160 S. First Avenue, Maywood, IL, 60153, USA
| | - Azul Zorzoli
- Department of Microbiology and Immunology, Loyola University Chicago - Stritch School of Medicine, 2160 S. First Avenue, Maywood, IL, 60153, USA
| | - Francis Alonzo
- Department of Microbiology and Immunology, Loyola University Chicago - Stritch School of Medicine, 2160 S. First Avenue, Maywood, IL, 60153, USA
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Dickey SW, Otto M. Lipoyl-E2-PDH Gets a Second Job. Cell Host Microbe 2018; 22:581-583. [PMID: 29120739 DOI: 10.1016/j.chom.2017.10.018] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
Pyruvate dehydrogenase (PDH) plays a well-known metabolic role inside cells. In this issue of Cell Host & Microbe, Grayczyk et al. (2017) show that the bacterial pathogen Staphylococcus aureus unexpectedly secretes and repurposes the lipoylated E2 subunit of PDH to suppress TLR-mediated activation of host macrophages by bacterial lipoproteins.
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Affiliation(s)
- Seth W Dickey
- Pathogen Molecular Genetics Section, Laboratory of Bacteriology, National Institute of Allergy and Infectious Diseases, U.S. National Institutes of Health, Bethesda, MD, USA
| | - Michael Otto
- Pathogen Molecular Genetics Section, Laboratory of Bacteriology, National Institute of Allergy and Infectious Diseases, U.S. National Institutes of Health, Bethesda, MD, USA.
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