1
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Gardner TM, Grosser MR. A MRSA mystery: how PBP4 and cyclic-di-AMP join forces against β-lactam antibiotics. mBio 2024; 15:e0121024. [PMID: 39028200 DOI: 10.1128/mbio.01210-24] [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] [Indexed: 07/20/2024] Open
Abstract
The high-level resistance to next-generation β-lactams frequently found in Staphylococcus aureus isolates lacking mec, which encodes the transpeptidase PBP2a traditionally associated with methicillin-resistant Staphylococcus aureus (MRSA), has remained incompletely understood for decades. A new study by Lai et al. found that the co-occurrence of mutations in pbp4 and gdpP, which respectively cause increased PBP4-mediated cell wall crosslinking and elevated cyclic-di-AMP levels, produces synergistic β-lactam resistance rivaling that of PBP2a-producing MRSA (L.-Y. Lai, N. Satishkumar, S. Cardozo, V. Hemmadi, et al., mBio 15:e02889-23. 2024, https://doi.org/10.1128/mbio.02889-23). The combined mutations are sufficient to explain the high-level β-lactam resistance of some mec-lacking strains, but the mechanism of synergy remains elusive and an avenue for further research. Importantly, the authors establish that co-occurrence of these mutations leads to antibiotic therapy failure in a Caenorhabditis elegans infection model. These results underscore the need to consider this unique and novel β-lactam resistance mechanism during the clinical diagnosis of MRSA, rather than relying on mec as a diagnostic.
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Affiliation(s)
- Taylor M Gardner
- Department of Biology, University of North Carolina Asheville, Asheville, North Carolina, USA
| | - Melinda R Grosser
- Department of Biology, University of North Carolina Asheville, Asheville, North Carolina, USA
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2
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Foster AJ, van den Noort M, Poolman B. Bacterial cell volume regulation and the importance of cyclic di-AMP. Microbiol Mol Biol Rev 2024; 88:e0018123. [PMID: 38856222 DOI: 10.1128/mmbr.00181-23] [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] [Indexed: 06/11/2024] Open
Abstract
SUMMARYNucleotide-derived second messengers are present in all domains of life. In prokaryotes, most of their functionality is associated with general lifestyle and metabolic adaptations, often in response to environmental fluctuations of physical parameters. In the last two decades, cyclic di-AMP has emerged as an important signaling nucleotide in many prokaryotic lineages, including Firmicutes, Actinobacteria, and Cyanobacteria. Its importance is highlighted by the fact that both the lack and overproduction of cyclic di-AMP affect viability of prokaryotes that utilize cyclic di-AMP, and that it generates a strong innate immune response in eukaryotes. In bacteria that produce the second messenger, most molecular targets of cyclic di-AMP are associated with cell volume control. Besides, other evidence links the second messenger to cell wall remodeling, DNA damage repair, sporulation, central metabolism, and the regulation of glycogen turnover. In this review, we take a biochemical, quantitative approach to address the main cellular processes that are directly regulated by cyclic di-AMP and show that these processes are very connected and require regulation of a similar set of proteins to which cyclic di-AMP binds. Altogether, we argue that cyclic di-AMP is a master regulator of cell volume and that other cellular processes can be connected with cyclic di-AMP through this core function. We further highlight important directions in which the cyclic di-AMP field has to develop to gain a full understanding of the cyclic di-AMP signaling network and why some processes are regulated, while others are not.
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Affiliation(s)
- Alexander J Foster
- Department of Biochemistry, Groningen Biomolecular Science and Biotechnology Institute, University of Groningen, Groningen, the Netherlands
| | - Marco van den Noort
- Department of Biochemistry, Groningen Biomolecular Science and Biotechnology Institute, University of Groningen, Groningen, the Netherlands
| | - Bert Poolman
- Department of Biochemistry, Groningen Biomolecular Science and Biotechnology Institute, University of Groningen, Groningen, the Netherlands
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3
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Rocha R, Jorge JMP, Teixeira-Duarte CM, Figueiredo-Costa IR, Cereija TB, Ferreira-Teixeira PF, Herzberg C, Stülke J, Morais-Cabral JH. c-di-AMP determines the hierarchical organization of bacterial RCK proteins. Proc Natl Acad Sci U S A 2024; 121:e2318666121. [PMID: 38652747 PMCID: PMC11067040 DOI: 10.1073/pnas.2318666121] [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: 10/25/2023] [Accepted: 03/13/2024] [Indexed: 04/25/2024] Open
Abstract
In bacteria, intracellular K+ is involved in the regulation of membrane potential, cytosolic pH, and cell turgor as well as in spore germination, environmental adaptation, cell-to-cell communication in biofilms, antibiotic sensitivity, and infectivity. The second messenger cyclic-di-AMP (c-di-AMP) has a central role in modulating the intracellular K+ concentration in many bacterial species, controlling transcription and function of K+ channels and transporters. However, our understanding of how this regulatory network responds to c-di-AMP remains poor. We used the RCK (Regulator of Conductance of K+) proteins that control the activity of Ktr channels in Bacillus subtilis as a model system to analyze the regulatory function of c-di-AMP with a combination of in vivo and in vitro functional and structural characterization. We determined that the two RCK proteins (KtrA and KtrC) are neither physiologically redundant or functionally equivalent. KtrC is the physiologically dominant RCK protein in the regulation of Ktr channel activity. In explaining this hierarchical organization, we found that, unlike KtrA, KtrC is very sensitive to c-di-AMP inactivation and lack of c-di-AMP regulation results in RCK protein toxicity, most likely due to unregulated K+ flux. We also found that KtrC can assemble with KtrA, conferring c-di-AMP regulation to the functional KtrA/KtrC heteromers and potentially compensating KtrA toxicity. Altogether, we propose that the central role of c-di-AMP in the control of the K+ machinery, by modulating protein levels through gene transcription and by regulating protein activity, has determined the evolutionary selection of KtrC as the dominant RCK protein, shaping the hierarchical organization of regulatory components of the K+ machinery.
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Affiliation(s)
- Rita Rocha
- Instituto de Investigação e Inovação em Saúde, Universidade do Porto, Porto4200-135, Portugal
- Instituto de Biologia Molecular e Celular, Universidade do Porto, Porto4200-135, Portugal
| | - João M. P. Jorge
- Instituto de Investigação e Inovação em Saúde, Universidade do Porto, Porto4200-135, Portugal
- Instituto de Biologia Molecular e Celular, Universidade do Porto, Porto4200-135, Portugal
| | - Celso M. Teixeira-Duarte
- Instituto de Investigação e Inovação em Saúde, Universidade do Porto, Porto4200-135, Portugal
- Instituto de Biologia Molecular e Celular, Universidade do Porto, Porto4200-135, Portugal
| | | | - Tatiana B. Cereija
- Instituto de Investigação e Inovação em Saúde, Universidade do Porto, Porto4200-135, Portugal
| | | | - Christina Herzberg
- Department of General Microbiology, Institute for Microbiology and Genetics, Georg-August-University Göttingen, Göttingen37073, Germany
| | - Jörg Stülke
- Department of General Microbiology, Institute for Microbiology and Genetics, Georg-August-University Göttingen, Göttingen37073, Germany
| | - João H. Morais-Cabral
- Instituto de Investigação e Inovação em Saúde, Universidade do Porto, Porto4200-135, Portugal
- Instituto de Biologia Molecular e Celular, Universidade do Porto, Porto4200-135, Portugal
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4
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Dengler Haunreiter V, Tarnutzer A, Bär J, von Matt M, Hertegonne S, Andreoni F, Vulin C, Künzi L, Menzi C, Kiefer P, Christen P, Vorholt JA, Zinkernagel AS. C-di-AMP levels modulate Staphylococcus aureus cell wall thickness, response to oxidative stress, and antibiotic resistance and tolerance. Microbiol Spectr 2023; 11:e0278823. [PMID: 37948390 PMCID: PMC10715141 DOI: 10.1128/spectrum.02788-23] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2023] [Accepted: 10/12/2023] [Indexed: 11/12/2023] Open
Abstract
IMPORTANCE Antibiotic resistance and tolerance are substantial healthcare-related problems, hampering effective treatment of bacterial infections. Mutations in the phosphodiesterase GdpP, which degrades cyclic di-3', 5'-adenosine monophosphate (c-di-AMP), have recently been associated with resistance to beta-lactam antibiotics in clinical Staphylococcus aureus isolates. In this study, we show that high c-di-AMP levels decreased the cell size and increased the cell wall thickness in S. aureus mutant strains. As a consequence, an increase in resistance to cell wall targeting antibiotics, such as oxacillin and fosfomycin as well as in tolerance to ceftaroline, a cephalosporine used to treat methicillin-resistant S. aureus infections, was observed. These findings underline the importance of investigating the role of c-di-AMP in the development of tolerance and resistance to antibiotics in order to optimize treatment in the clinical setting.
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Affiliation(s)
- Vanina Dengler Haunreiter
- Department of Infectious Diseases and Hospital Epidemiology, University Hospital Zurich, University of Zurich, Zurich, Switzerland
| | - Andrea Tarnutzer
- Department of Infectious Diseases and Hospital Epidemiology, University Hospital Zurich, University of Zurich, Zurich, Switzerland
| | - Julian Bär
- Department of Infectious Diseases and Hospital Epidemiology, University Hospital Zurich, University of Zurich, Zurich, Switzerland
| | - Manuela von Matt
- Department of Infectious Diseases and Hospital Epidemiology, University Hospital Zurich, University of Zurich, Zurich, Switzerland
| | - Sanne Hertegonne
- Department of Infectious Diseases and Hospital Epidemiology, University Hospital Zurich, University of Zurich, Zurich, Switzerland
| | - Federica Andreoni
- Department of Infectious Diseases and Hospital Epidemiology, University Hospital Zurich, University of Zurich, Zurich, Switzerland
| | - Clément Vulin
- Department of Infectious Diseases and Hospital Epidemiology, University Hospital Zurich, University of Zurich, Zurich, Switzerland
| | - Lisa Künzi
- Department of Infectious Diseases and Hospital Epidemiology, University Hospital Zurich, University of Zurich, Zurich, Switzerland
| | - Carmen Menzi
- Department of Infectious Diseases and Hospital Epidemiology, University Hospital Zurich, University of Zurich, Zurich, Switzerland
| | - Patrick Kiefer
- Department of Biology, Institute of Microbiology, ETH Zurich, Zurich, Switzerland
| | - Philipp Christen
- Department of Biology, Institute of Microbiology, ETH Zurich, Zurich, Switzerland
| | - Julia A. Vorholt
- Department of Biology, Institute of Microbiology, ETH Zurich, Zurich, Switzerland
| | - Annelies S. Zinkernagel
- Department of Infectious Diseases and Hospital Epidemiology, University Hospital Zurich, University of Zurich, Zurich, Switzerland
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5
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Putriningsih PAS, Phuektes P, Jittimanee S, Kampa J. Methicillin-resistant Staphylococci in canine pyoderma in Thailand. Vet World 2023; 16:2340-2348. [PMID: 38152262 PMCID: PMC10750743 DOI: 10.14202/vetworld.2023.2340-2348] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2023] [Accepted: 10/17/2023] [Indexed: 12/29/2023] Open
Abstract
Background and Aims Methicillin-resistant Staphylococci (MRS) seriously threatens animal and human health. Repeated antibiotic use allows the bacteria to develop resistance to several antibiotic classes and become multidrug-resistant (MDR). Canine pyoderma, a common skin condition in dogs, is mainly caused by Staphylococci, including MRS. Detecting this infection in all canine populations is crucial to develop a proper preventive plan. This study estimated the prevalence, antibiogram, and risk factors of MRS in canine patients at a referral animal hospital in Khon Kaen, Thailand. Materials and Methods Skin swabs and relevant information were collected from 56 client-owned dogs that visited the hospital from September 2019 to September 2020. Staphylococci colonies were subjected to molecular identification and antibiotic susceptibility tests using an automated system (VITEK® 2). These colonies were also genetically identified using multiplex-polymerase chain reaction (PCR) and sequencing. The mecA gene, encoding methicillin resistance, was detected using simplex-PCR. The risk factors of MRS infection and their association with MRS infection were analyzed using logistic regression and the Chi-square test, respectively. Results The prevalence of MRS was found to be 35.7% (20/56 dogs). By species, methicillin-resistant Staphylococcus pseudintermedius was found in 24 of 104 isolates (23.1%), and all samples were MDR. Receiving systemic antibiotics in the past 6 months was a major risk factor associated with MRS infection (p < 0.05; odds ratio (OR) > 1). In addition to the MRS isolates, the mecA gene was also detected in methicillin-susceptible Staphylococci isolates. This might be because of the high expression of blaI, and mutations in c-di-AMP cyclase DacA, RelA, and Fem proteins. Conclusion A high prevalence of MRS and MDR was observed in the studied population, which might be potentially due to improper antibiotic use by the owners and horizontal transfer of drug-resistance genes.
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Affiliation(s)
- Putu Ayu Sisyawati Putriningsih
- Graduate School, Faculty of Veterinary Medicine, Khon Kaen University, Khon Kaen, 40002, Thailand
- Laboratory of Veterinary Internal Medicine, Faculty of Veterinary Medicine, Udayana University, Bali, 80361, Indonesia
| | - Patchara Phuektes
- Division of Pathobiology, Faculty of Veterinary Medicine, Khon Kaen University, Khon Kaen, 40002, Thailand
| | - Suphattra Jittimanee
- Division of Pathobiology, Faculty of Veterinary Medicine, Khon Kaen University, Khon Kaen, 40002, Thailand
| | - Jaruwan Kampa
- Division of Pathobiology, Faculty of Veterinary Medicine, Khon Kaen University, Khon Kaen, 40002, Thailand
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6
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Purine Nucleosides Interfere with c-di-AMP Levels and Act as Adjuvants To Re-Sensitize MRSA To β-Lactam Antibiotics. mBio 2023; 14:e0247822. [PMID: 36507833 PMCID: PMC9973305 DOI: 10.1128/mbio.02478-22] [Citation(s) in RCA: 13] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
The purine-derived signaling molecules c-di-AMP and (p)ppGpp control mecA/PBP2a-mediated β-lactam resistance in methicillin-resistant Staphylococcus aureus (MRSA) raise the possibility that purine availability can control antibiotic susceptibility. Consistent with this, exogenous guanosine and xanthosine, which are fluxed through the GTP branch of purine biosynthesis, were shown to significantly reduce MRSA β-lactam resistance. In contrast, adenosine (fluxed to ATP) significantly increased oxacillin resistance, whereas inosine (which can be fluxed to ATP and GTP via hypoxanthine) only marginally increased oxacillin susceptibility. Furthermore, mutations that interfere with de novo purine synthesis (pur operon), transport (NupG, PbuG, PbuX) and the salvage pathway (DeoD2, Hpt) increased β-lactam resistance in MRSA strain JE2. Increased resistance of a nupG mutant was not significantly reversed by guanosine, indicating that NupG is required for guanosine transport, which is required to reduce β-lactam resistance. Suppressor mutants resistant to oxacillin/guanosine combinations contained several purine salvage pathway mutations, including nupG and hpt. Guanosine significantly increased cell size and reduced levels of c-di-AMP, while inactivation of GdpP, the c-di-AMP phosphodiesterase negated the impact of guanosine on β-lactam susceptibility. PBP2a expression was unaffected in nupG or deoD2 mutants, suggesting that guanosine-induced β-lactam susceptibility may result from dysfunctional c-di-AMP-dependent osmoregulation. These data reveal the therapeutic potential of purine nucleosides, as β-lactam adjuvants that interfere with the normal activation of c-di-AMP are required for high-level β-lactam resistance in MRSA. IMPORTANCE The clinical burden of infections caused by antimicrobial resistant (AMR) pathogens is a leading threat to public health. Maintaining the effectiveness of existing antimicrobial drugs or finding ways to reintroduce drugs to which resistance is widespread is an important part of efforts to address the AMR crisis. Predominantly, the safest and most effective class of antibiotics are the β-lactams, which are no longer effective against methicillin-resistant Staphylococcus aureus (MRSA). Here, we report that the purine nucleosides guanosine and xanthosine have potent activity as adjuvants that can resensitize MRSA to oxacillin and other β-lactam antibiotics. Mechanistically, exposure of MRSA to these nucleosides significantly reduced the levels of the cyclic dinucleotide c-di-AMP, which is required for β-lactam resistance. Drugs derived from nucleotides are widely used in the treatment of cancer and viral infections highlighting the clinical potential of using purine nucleosides to restore or enhance the therapeutic effectiveness of β-lactams against MRSA and potentially other AMR pathogens.
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7
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Functional mgrA Influences Genetic Changes within a Staphylococcus aureus Cell Population over Time. J Bacteriol 2022; 204:e0013822. [PMID: 36154359 DOI: 10.1128/jb.00138-22] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Prolonged survival in the host-bacteria microenvironment drives the selection of alternative cell types in Staphylococcus aureus, permitting quasi-dormant sub-populations to develop. These facilitate antibiotic tolerance, long-term growth, and relapse of infection. Small Colony Variants (SCV) are an important cell type associated with persistent infection but are difficult to study in vitro due to the instability of the phenotype and reversion to the normal cell type. We have previously reported that under conditions of growth in continuous culture over a prolonged culture time, SCVs dominated a heterogenous population of cell types and these SCVs harbored a mutation in the DNA binding domain of the gene for the transcription factor, mgrA. To investigate this specific cell type further, S. aureus WCH-SK2-ΔmgrA itself was assessed with continuous culture. Compared to the wild type, the mgrA mutant strain required fewer generations to select for SCVs. There was an increased rate of mutagenesis within the ΔmgrA strain compared to the wild type, which we postulate is the mechanism explaining the increased emergence of SCV selection. The mgrA derived SCVs had impeded metabolism, altered MIC to specific antibiotics and an increased biofilm formation compared to non-SCV strain. Whole genomic sequencing detected single nucleotide polymorphisms (SNP) in phosphoglucosamine mutase glmM and tyrosine recombinase xerC. In addition, several genomic rearrangements were detected which affected genes involved in important functions such as antibiotic and toxic metal resistance and pathogenicity. Thus, we propose a direct link between mgrA and the SCV phenotype. IMPORTANCE Within a bacterial population, a stochastically generated heterogeneity of phenotypes allows continual survival against current and future stressors. The generation of a sub-population of quasi-dormant Small Colony Variants (SCV) in Staphylococcus aureus is such a mechanism, allowing for persistent or relapse of infection despite initial intervention seemingly clearing the infection. The use of continuous culture under clinically relevant conditions has allowed us to introduce time to the growth system and selects SCV within the population. This study provides valuable insights into the generation of SCV which are not addressed in standard laboratory generated models and reveals new pathways for understanding persistent S. aureus infection which can potentially be targeted in future treatments of persistent S. aureus infection.
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8
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Moradali MF, Ghods S, Bähre H, Lamont RJ, Scott DA, Seifert R. Atypical cyclic di-AMP signaling is essential for Porphyromonas gingivalis growth and regulation of cell envelope homeostasis and virulence. NPJ Biofilms Microbiomes 2022; 8:53. [PMID: 35794154 PMCID: PMC9259658 DOI: 10.1038/s41522-022-00316-w] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2022] [Accepted: 06/13/2022] [Indexed: 02/04/2023] Open
Abstract
Microbial pathogens employ signaling systems through cyclic (di-) nucleotide monophosphates serving as second messengers to increase fitness during pathogenesis. However, signaling schemes via second messengers in Porphyromonas gingivalis, a key Gram-negative anaerobic oral pathogen, remain unknown. Here, we report that among various ubiquitous second messengers, P. gingivalis strains predominantly synthesize bis-(3',5')-cyclic di-adenosine monophosphate (c-di-AMP), which is essential for their growth and survival. Our findings demonstrate an unusual regulation of c-di-AMP synthesis in P. gingivalis. P. gingivalis c-di-AMP phosphodiesterase (PDE) gene (pdepg) positively regulates c-di-AMP synthesis and impedes a decrease in c-di-AMP concentration despite encoding conserved amino acid motifs for phosphodiesterase activity. Instead, the predicted regulator gene cdaR, unrelated to the c-di-AMP PDE genes, serves as a potent negative regulator of c-di-AMP synthesis in this anaerobe. Further, our findings reveal that pdepg and cdaR are required to regulate the incorporation of ATP into c-di-AMP upon pyruvate utilization, leading to enhanced biofilm formation. We show that shifts in c-di-AMP signaling change the integrity and homeostasis of cell envelope, importantly, the structure and immunoreactivity of the lipopolysaccharide layer. Additionally, microbe-microbe interactions and the virulence potential of P. gingivalis were modulated by c-di-AMP. These studies provide the first glimpse into the scheme of second messenger signaling in P. gingivalis and perhaps other Bacteroidetes. Further, our findings indicate that c-di-AMP signaling promotes the fitness of the residents of the oral cavity and the development of a pathogenic community.
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Affiliation(s)
- M Fata Moradali
- Department of Oral Immunology and Infectious Diseases, University of Louisville, School of Dentistry, Louisville, KY, USA.
| | - Shirin Ghods
- Department of Oral Immunology and Infectious Diseases, University of Louisville, School of Dentistry, Louisville, KY, USA
| | - Heike Bähre
- Research Core Unit Metabolomics, Hannover Medical School, Hanover, Germany
| | - Richard J Lamont
- Department of Oral Immunology and Infectious Diseases, University of Louisville, School of Dentistry, Louisville, KY, USA
| | - David A Scott
- Department of Oral Immunology and Infectious Diseases, University of Louisville, School of Dentistry, Louisville, KY, USA
| | - Roland Seifert
- Research Core Unit Metabolomics, Hannover Medical School, Hanover, Germany
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9
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An Interplay of Multiple Positive and Negative Factors Governs Methicillin Resistance in Staphylococcus aureus. Microbiol Mol Biol Rev 2022; 86:e0015921. [PMID: 35420454 PMCID: PMC9199415 DOI: 10.1128/mmbr.00159-21] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The development of resistance to β-lactam antibiotics has made Staphylococcus aureus a clinical burden on a global scale. MRSA (methicillin-resistant S. aureus) is commonly known as a superbug. The ability of MRSA to proliferate in the presence of β-lactams is attributed to the acquisition of mecA, which encodes the alternative penicillin binding protein, PBP2A, which is insensitive to the antibiotics. Most MRSA isolates exhibit low-level β-lactam resistance, whereby additional genetic adjustments are required to develop high-level resistance. Although several genetic factors that potentiate or are required for high-level resistance have been identified, how these interact at the mechanistic level has remained elusive. Here, we discuss the development of resistance and assess the role of the associated components in tailoring physiology to accommodate incoming mecA.
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10
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Tang Q, Precit MR, Thomason MK, Blanc SF, Ahmed-Qadri F, McFarland AP, Wolter DJ, Hoffman LR, Woodward JJ. Thymidine starvation promotes c-di-AMP-dependent inflammation during pathogenic bacterial infection. Cell Host Microbe 2022; 30:961-974.e6. [PMID: 35439435 DOI: 10.1016/j.chom.2022.03.028] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2021] [Revised: 02/01/2022] [Accepted: 03/23/2022] [Indexed: 11/03/2022]
Abstract
Antimicrobials can impact bacterial physiology and host immunity with negative treatment outcomes. Extensive exposure to antifolate antibiotics promotes thymidine-dependent Staphylococcus aureus small colony variants (TD-SCVs), commonly associated with worse clinical outcomes. We show that antibiotic-mediated disruption of thymidine synthesis promotes elevated levels of the bacterial second messenger cyclic di-AMP (c-di-AMP), consequently inducing host STING activation and inflammation. An initial antibiotic screen in Firmicutes revealed that c-di-AMP production was largely driven by antifolate antibiotics targeting dihydrofolate reductase (DHFR), which promotes folate regeneration required for thymidine biosynthesis. Additionally, TD-SCVs exhibited excessive c-di-AMP production and STING activation in a thymidine-dependent manner. Murine lung infection with TD-SCVs revealed STING-dependent elevation of proinflammatory cytokines, causing higher airway neutrophil infiltration and activation compared with normal-colony S. aureus and hemin-dependent SCVs. Collectively, our results suggest that thymidine metabolism disruption in Firmicutes leads to elevated c-di-AMP-mediated STING-dependent inflammation, with potential impacts on antibiotic usage and infection outcomes.
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Affiliation(s)
- Qing Tang
- Department of Microbiology, University of Washington, Seattle, WA 98105, USA
| | - Mimi R Precit
- Department of Microbiology, University of Washington, Seattle, WA 98105, USA
| | - Maureen K Thomason
- Department of Microbiology, University of Washington, Seattle, WA 98105, USA
| | - Sophie F Blanc
- Department of Microbiology, University of Washington, Seattle, WA 98105, USA
| | - Fariha Ahmed-Qadri
- Department of Microbiology, University of Washington, Seattle, WA 98105, USA
| | - Adelle P McFarland
- Department of Microbiology, University of Washington, Seattle, WA 98105, USA
| | - Daniel J Wolter
- Department of Pediatrics, University of Washington, Seattle, WA 98105, USA; Pulmonary and Sleep Medicine, Seattle Children's Hospital, Seattle, WA 98105, USA
| | - Lucas R Hoffman
- Department of Microbiology, University of Washington, Seattle, WA 98105, USA; Department of Pediatrics, University of Washington, Seattle, WA 98105, USA; Pulmonary and Sleep Medicine, Seattle Children's Hospital, Seattle, WA 98105, USA
| | - Joshua J Woodward
- Department of Microbiology, University of Washington, Seattle, WA 98105, USA.
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11
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Pseudomonas aeruginosa
Oligoribonuclease Controls Susceptibility to Polymyxin B by Regulating Pel Exopolysaccharide Production. Antimicrob Agents Chemother 2022; 66:e0207221. [DOI: 10.1128/aac.02072-21] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Polymyxins are considered as the last resort antibiotics to treat infections caused by multidrug-resistant Gram negative pathogens.
Pseudomonas aeruginosa
is an opportunistic pathogen that causes various infections in humans. Proteins involved in lipopolysaccharide modification and maintaining inner and outer membrane integrities have been found to contribute to the bacterial resistance to polymyxins. Oligoribonuclease (Orn) is an exonuclease that regulates the homeostasis of intracellular (3'-5')-cyclic dimeric guanosine monophosphate (c-di-GMP), thereby regulating the production of extracellular polysaccharide in
P. aeruginosa
. Previously, we demonstrated that Orn affects the bacterial resistance to fluoroquinolone, β-lactam and aminoglycoside antibiotics. In this study, we found that mutation of
orn
increased the bacterial survival following polymyxin B treatment in a wild type
P. aeruginosa
strain PA14. Overexpression of c-di-GMP degradation enzymes in the
orn
mutant reduced the bacterial survival. By using a fluorescence labeled polymyxin B, we found that mutation of
orn
increased the bacterial surface bound polymyxin B. Deletion of the Pel synthesis genes or treatment with a Pel hydrolase reduced the surface bound polymyxin B and bacterial survival. We further demonstrated that Pel binds to extracellular DNA (eDNA), which traps polymyxin B and thus protects the bacterial cells. Collectively, our results revealed a novel defense mechanism against polymyxin in
P. aeruginosa
.
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12
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New Mechanistic Insights into Purine Biosynthesis with Second Messenger c-di-AMP in Relation to Biofilm-Related Persistent Methicillin-Resistant Staphylococcus aureus Infections. mBio 2021; 12:e0208121. [PMID: 34724823 PMCID: PMC8561390 DOI: 10.1128/mbio.02081-21] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Persistent methicillin-resistant Staphylococcus aureus (MRSA) endovascular infections represent a significant clinically challenging subset of invasive, life-threatening S. aureus infections. We have recently demonstrated that purine biosynthesis plays an important role in such persistent infections. Cyclic di-AMP (c-di-AMP) is an essential and ubiquitous second messenger that regulates many cellular pathways in bacteria. However, whether there is a regulatory connection between the purine biosynthesis pathway and c-di-AMP impacting persistent outcomes was not known. Here, we demonstrated that the purine biosynthesis mutant MRSA strain, the ΔpurF strain (compared to its isogenic parental strain), exhibited the following significant differences in vitro: (i) lower ADP, ATP, and c-di-AMP levels; (ii) less biofilm formation with decreased extracellular DNA (eDNA) levels and Triton X-100-induced autolysis paralleling enhanced expressions of the biofilm formation-related two-component regulatory system lytSR and its downstream gene lrgB; (iii) increased vancomycin (VAN)-binding and VAN-induced lysis; and (iv) decreased wall teichoic acid (WTA) levels and expression of the WTA biosynthesis-related gene, tarH. Substantiating these data, the dacA (encoding diadenylate cyclase enzyme required for c-di-AMP synthesis) mutant strain (dacAG206S strain versus its isogenic wild-type MRSA and dacA-complemented strains) showed significantly decreased c-di-AMP levels, similar in vitro effects as seen above for the purF mutant and hypersusceptible to VAN treatment in an experimental biofilm-related MRSA endovascular infection model. These results reveal an important intersection between purine biosynthesis and c-di-AMP that contributes to biofilm-associated persistence in MRSA endovascular infections. This signaling pathway represents a logical therapeutic target against persistent MRSA infections.
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13
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Wood DM, Dobson RC, Horne CR. Using cryo-EM to uncover mechanisms of bacterial transcriptional regulation. Biochem Soc Trans 2021; 49:2711-2726. [PMID: 34854920 PMCID: PMC8786299 DOI: 10.1042/bst20210674] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2021] [Revised: 11/10/2021] [Accepted: 11/15/2021] [Indexed: 11/17/2022]
Abstract
Transcription is the principal control point for bacterial gene expression, and it enables a global cellular response to an intracellular or environmental trigger. Transcriptional regulation is orchestrated by transcription factors, which activate or repress transcription of target genes by modulating the activity of RNA polymerase. Dissecting the nature and precise choreography of these interactions is essential for developing a molecular understanding of transcriptional regulation. While the contribution of X-ray crystallography has been invaluable, the 'resolution revolution' of cryo-electron microscopy has transformed our structural investigations, enabling large, dynamic and often transient transcription complexes to be resolved that in many cases had resisted crystallisation. In this review, we highlight the impact cryo-electron microscopy has had in gaining a deeper understanding of transcriptional regulation in bacteria. We also provide readers working within the field with an overview of the recent innovations available for cryo-electron microscopy sample preparation and image reconstruction of transcription complexes.
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Affiliation(s)
- David M. Wood
- Biomolecular Interaction Centre and School of Biological Sciences, University of Canterbury, Christchurch, New Zealand
| | - Renwick C.J. Dobson
- Biomolecular Interaction Centre and School of Biological Sciences, University of Canterbury, Christchurch, New Zealand
- Bio21 Molecular Science and Biotechnology Institute, Department of Biochemistry and Pharmacology, University of Melbourne, Parkville, VIC, Australia
| | - Christopher R. Horne
- Walter and Eliza Hall Institute of Medical Research, 1G Royal Parade, Parkville, VIC 3052, Australia
- Department of Medical Biology, University of Melbourne, Parkville, VIC 3052, Australia
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14
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Pathania M, Tosi T, Millership C, Hoshiga F, Morgan RML, Freemont PS, Gründling A. Structural basis for the inhibition of the Bacillus subtilis c-di-AMP cyclase CdaA by the phosphoglucomutase GlmM. J Biol Chem 2021; 297:101317. [PMID: 34678313 PMCID: PMC8573169 DOI: 10.1016/j.jbc.2021.101317] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2021] [Revised: 10/15/2021] [Accepted: 10/18/2021] [Indexed: 11/25/2022] Open
Abstract
Cyclic-di-adenosine monophosphate (c-di-AMP) is an important nucleotide signaling molecule that plays a key role in osmotic regulation in bacteria. c-di-AMP is produced from two molecules of ATP by proteins containing a diadenylate cyclase (DAC) domain. In Bacillus subtilis, the main c-di-AMP cyclase, CdaA, is a membrane-linked cyclase with an N-terminal transmembrane domain followed by the cytoplasmic DAC domain. As both high and low levels of c-di-AMP have a negative impact on bacterial growth, the cellular levels of this signaling nucleotide are tightly regulated. Here we investigated how the activity of the B. subtilis CdaA is regulated by the phosphoglucomutase GlmM, which has been shown to interact with the c-di-AMP cyclase. Using the soluble B. subtilis CdaACD catalytic domain and purified full-length GlmM or the GlmMF369 variant lacking the C-terminal flexible domain 4, we show that the cyclase and phosphoglucomutase form a stable complex in vitro and that GlmM is a potent cyclase inhibitor. We determined the crystal structure of the individual B. subtilis CdaACD and GlmM homodimers and of the CdaACD:GlmMF369 complex. In the complex structure, a CdaACD dimer is bound to a GlmMF369 dimer in such a manner that GlmM blocks the oligomerization of CdaACD and formation of active head-to-head cyclase oligomers, thus suggesting a mechanism by which GlmM acts as a cyclase inhibitor. As the amino acids at the CdaACD:GlmM interphase are conserved, we propose that the observed mechanism of inhibition of CdaA by GlmM may also be conserved among Firmicutes.
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Affiliation(s)
- Monisha Pathania
- Section of Molecular Microbiology and Medical Research Council Centre for Molecular Bacteriology and Infection, Imperial College London, London, United Kingdom
| | - Tommaso Tosi
- Section of Molecular Microbiology and Medical Research Council Centre for Molecular Bacteriology and Infection, Imperial College London, London, United Kingdom
| | - Charlotte Millership
- Section of Molecular Microbiology and Medical Research Council Centre for Molecular Bacteriology and Infection, Imperial College London, London, United Kingdom
| | - Fumiya Hoshiga
- Section of Molecular Microbiology and Medical Research Council Centre for Molecular Bacteriology and Infection, Imperial College London, London, United Kingdom
| | - Rhodri M L Morgan
- Department of Life Sciences, Imperial College London, London, United Kingdom
| | - Paul S Freemont
- London Biofoundry, Imperial College Translation and Innovation Hub, White City Campus, London, United Kingdom; Section of Structural and Synthetic Biology, Department of Infectious Disease, Imperial College London, London, United Kingdom; UK Dementia Research Institute Centre for Care Research and Technology, Imperial College London, London, United Kingdom.
| | - Angelika Gründling
- Section of Molecular Microbiology and Medical Research Council Centre for Molecular Bacteriology and Infection, Imperial College London, London, United Kingdom.
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15
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Kundra S, Lam LN, Kajfasz JK, Casella LG, Andersen MJ, Abranches J, Flores-Mireles AL, Lemos JA. c-di-AMP Is Essential for the Virulence of Enterococcus faecalis. Infect Immun 2021; 89:e0036521. [PMID: 34424750 PMCID: PMC8519298 DOI: 10.1128/iai.00365-21] [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: 07/01/2021] [Accepted: 08/11/2021] [Indexed: 12/12/2022] Open
Abstract
Second messenger nucleotides are produced by bacteria in response to environmental stimuli and play a major role in the regulation of processes associated with bacterial fitness, including but not limited to osmoregulation, envelope homeostasis, central metabolism, and biofilm formation. In this study, we uncovered the biological significance of c-di-AMP in the opportunistic pathogen Enterococcus faecalis by isolating and characterizing strains lacking genes responsible for c-di-AMP synthesis (cdaA) and degradation (dhhP and gdpP). Using complementary approaches, we demonstrated that either complete loss of c-di-AMP (ΔcdaA strain) or c-di-AMP accumulation (ΔdhhP, ΔgdpP, and ΔdhhP ΔgdpP strains) drastically impaired general cell fitness and virulence of E. faecalis. In particular, the ΔcdaA strain was highly sensitive to envelope-targeting antibiotics, was unable to multiply and quickly lost viability in human serum or urine ex vivo, and was virtually avirulent in an invertebrate (Galleria mellonella) and in two catheter-associated mouse infection models that recapitulate key aspects of enterococcal infections in humans. In addition to evidence linking these phenotypes to altered activity of metabolite and peptide transporters and inability to maintain osmobalance, we found that the attenuated virulence of the ΔcdaA strain also could be attributed to a defect in Ebp pilus production and activity that severely impaired biofilm formation under both in vitro and in vivo conditions. Collectively, these results demonstrate that c-di-AMP signaling is essential for E. faecalis pathogenesis and a desirable target for drug development.
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Affiliation(s)
- Shivani Kundra
- Department of Oral Biology, University of Florida College of Dentistry, Gainesville, Florida, USA
| | - Ling Ning Lam
- Department of Oral Biology, University of Florida College of Dentistry, Gainesville, Florida, USA
| | - Jessica K. Kajfasz
- Department of Oral Biology, University of Florida College of Dentistry, Gainesville, Florida, USA
| | - Leila G. Casella
- Department of Oral Biology, University of Florida College of Dentistry, Gainesville, Florida, USA
| | - Marissa J. Andersen
- Department of Biological Sciences, University of Norte Dame, Notre Dame, Indiana, USA
| | - Jacqueline Abranches
- Department of Oral Biology, University of Florida College of Dentistry, Gainesville, Florida, USA
| | - Ana L. Flores-Mireles
- Department of Biological Sciences, University of Norte Dame, Notre Dame, Indiana, USA
| | - José A. Lemos
- Department of Oral Biology, University of Florida College of Dentistry, Gainesville, Florida, USA
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16
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Bandera AM, Bartho J, Lammens K, Drexler DJ, Kleinschwärzer J, Hopfner KP, Witte G. BusR senses bipartite DNA binding motifs by a unique molecular ruler architecture. Nucleic Acids Res 2021; 49:10166-10177. [PMID: 34432045 PMCID: PMC8517857 DOI: 10.1093/nar/gkab736] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2021] [Revised: 07/27/2021] [Accepted: 08/12/2021] [Indexed: 12/18/2022] Open
Abstract
The cyclic dinucleotide second messenger c-di-AMP is a major player in regulation of potassium homeostasis and osmolyte transport in a variety of bacteria. Along with various direct interactions with proteins such as potassium channels, the second messenger also specifically binds to transcription factors, thereby altering the processes in the cell on the transcriptional level. We here describe the structural and biochemical characterization of BusR from the human pathogen Streptococcus agalactiae. BusR is a member of a yet structurally uncharacterized subfamily of the GntR family of transcription factors that downregulates transcription of the genes for the BusA (OpuA) glycine-betaine transporter upon c-di-AMP binding. We report crystal structures of full-length BusR, its apo and c-di-AMP bound effector domain, as well as cryo-EM structures of BusR bound to its operator DNA. Our structural data, supported by biochemical and biophysical data, reveal that BusR utilizes a unique domain assembly with a tetrameric coiled-coil in between the binding platforms, serving as a molecular ruler to specifically recognize a 22 bp separated bipartite binding motif. Binding of c-di-AMP to BusR induces a shift in equilibrium from an inactivated towards an activated state that allows BusR to bind the target DNA, leading to transcriptional repression.
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Affiliation(s)
- Adrian M Bandera
- Gene Center, Ludwig-Maximilians-Universität München, Feodor-Lynen-Str. 25, D-81377 München, Germany.,Department of Biochemistry, Ludwig-Maximilians-Universität München, Feodor-Lynen-Str. 25, D-81377 München, Germany
| | - Joseph Bartho
- Gene Center, Ludwig-Maximilians-Universität München, Feodor-Lynen-Str. 25, D-81377 München, Germany.,Department of Biochemistry, Ludwig-Maximilians-Universität München, Feodor-Lynen-Str. 25, D-81377 München, Germany
| | - Katja Lammens
- Gene Center, Ludwig-Maximilians-Universität München, Feodor-Lynen-Str. 25, D-81377 München, Germany.,Department of Biochemistry, Ludwig-Maximilians-Universität München, Feodor-Lynen-Str. 25, D-81377 München, Germany
| | - David Jan Drexler
- Gene Center, Ludwig-Maximilians-Universität München, Feodor-Lynen-Str. 25, D-81377 München, Germany.,Department of Biochemistry, Ludwig-Maximilians-Universität München, Feodor-Lynen-Str. 25, D-81377 München, Germany
| | - Jasmin Kleinschwärzer
- Gene Center, Ludwig-Maximilians-Universität München, Feodor-Lynen-Str. 25, D-81377 München, Germany.,Department of Biochemistry, Ludwig-Maximilians-Universität München, Feodor-Lynen-Str. 25, D-81377 München, Germany
| | - Karl-Peter Hopfner
- Gene Center, Ludwig-Maximilians-Universität München, Feodor-Lynen-Str. 25, D-81377 München, Germany.,Department of Biochemistry, Ludwig-Maximilians-Universität München, Feodor-Lynen-Str. 25, D-81377 München, Germany
| | - Gregor Witte
- Gene Center, Ludwig-Maximilians-Universität München, Feodor-Lynen-Str. 25, D-81377 München, Germany.,Department of Biochemistry, Ludwig-Maximilians-Universität München, Feodor-Lynen-Str. 25, D-81377 München, Germany
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17
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Sommer A, Fuchs S, Layer F, Schaudinn C, Weber RE, Richard H, Erdmann MB, Laue M, Schuster CF, Werner G, Strommenger B. Mutations in the gdpP gene are a clinically relevant mechanism for β-lactam resistance in meticillin-resistant Staphylococcus aureus lacking mec determinants. Microb Genom 2021; 7. [PMID: 34486969 PMCID: PMC8715439 DOI: 10.1099/mgen.0.000623] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
In Staphylococcus aureus, resistance to β-lactamase stable β-lactam antibiotics is mediated by the penicillinbinding protein 2a, encoded by mecA or by its homologues mecB or mecC. However, a substantial number of meticillin-resistant isolates lack known mec genes and, thus, are called meticillin resistant lacking mec (MRLM). This study aims to identify the genetic mechanisms underlying the MRLM phenotype. A total of 141 MRLM isolates and 142 meticillin-susceptible controls were included in this study. Oxacillin and cefoxitin minimum inhibitory concentrations were determined by broth microdilution and the presence of mec genes was excluded by PCR. Comparative genomics and a genome-wide association study (GWAS) approach were applied to identify genetic polymorphisms associated with the MRLM phenotype. The potential impact of such mutations on the expression of PBP4, as well as on cell morphology and biofilm formation, was investigated. GWAS revealed that mutations in gdpP were significantly associated with the MRLM phenotype. GdpP is a phosphodiesterase enzyme involved in the degradation of the second messenger cyclic-di-AMP in S. aureus. A total of 131 MRLM isolates carried truncations, insertions or deletions as well as amino acid substitutions, mainly located in the functional DHH-domain of GdpP. We experimentally verified the contribution of these gdpP mutations to the MRLM phenotype by heterologous complementation experiments. The mutations in gdpP had no effect on transcription levels of pbp4; however, cell sizes of MRLM strains were reduced. The impact on biofilm formation was highly strain dependent. We report mutations in gdpP as a clinically relevant mechanism for β-lactam resistance in MRLM isolates. This observation is of particular clinical relevance, since MRLM are easily misclassified as MSSA (meticillin-susceptible S. aureus), which may lead to unnoticed spread of β-lactam-resistant isolates and subsequent treatment failure.
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Affiliation(s)
- Anna Sommer
- Department of Infectious Diseases, Nosocomial Pathogens and Antibiotic Resistances, Robert Koch Institute, Wernigerode, Germany
| | - Stephan Fuchs
- Methodology and Research Infrastructure, Bioinformatics, Robert Koch Institute, Berlin, Germany
| | - Franziska Layer
- Department of Infectious Diseases, Nosocomial Pathogens and Antibiotic Resistances, Robert Koch Institute, Wernigerode, Germany
| | - Christoph Schaudinn
- Centre for Biological Threats and Special Pathogens, Advanced Light and Electron Microscopy, Robert Koch Institute, Berlin, Germany
| | - Robert E Weber
- Department of Infectious Diseases, Nosocomial Pathogens and Antibiotic Resistances, Robert Koch Institute, Wernigerode, Germany
| | - Hugues Richard
- Methodology and Research Infrastructure, Bioinformatics, Robert Koch Institute, Berlin, Germany
| | - Mareike B Erdmann
- Department of Infectious Diseases, Nosocomial Pathogens and Antibiotic Resistances, Robert Koch Institute, Wernigerode, Germany
| | - Michael Laue
- Centre for Biological Threats and Special Pathogens, Advanced Light and Electron Microscopy, Robert Koch Institute, Berlin, Germany
| | - Christopher F Schuster
- Department of Infectious Diseases, Nosocomial Pathogens and Antibiotic Resistances, Robert Koch Institute, Wernigerode, Germany
| | - Guido Werner
- Department of Infectious Diseases, Nosocomial Pathogens and Antibiotic Resistances, Robert Koch Institute, Wernigerode, Germany
| | - Birgit Strommenger
- Department of Infectious Diseases, Nosocomial Pathogens and Antibiotic Resistances, Robert Koch Institute, Wernigerode, Germany
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18
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Rørvik GH, Naemi A, Edvardsen PKT, Simm R. The c-di-AMP signaling system influences stress tolerance and biofilm formation of Streptococcus mitis. Microbiologyopen 2021; 10:e1203. [PMID: 34459556 PMCID: PMC8289670 DOI: 10.1002/mbo3.1203] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2021] [Revised: 05/07/2021] [Accepted: 05/14/2021] [Indexed: 11/16/2022] Open
Abstract
Streptococcus mitis is a commensal bacterial species of the oral cavity, with the potential for opportunistic pathogenesis. For successful colonization, S. mitis must be able to adhere to surfaces of the oral cavity and survive and adapt to frequently changing environmental conditions. Cyclic-di-AMP (c-di-AMP) is a nucleotide second messenger, involved in the regulation of stress responses and biofilm formation in several bacterial species. Cyclic-di-AMP is produced by diadenylate cyclases and degraded by phosphodiesterases. We have previously shown that in S. mitis, one diadenylate cyclase (CdaA) and at least two phosphodiesterases (Pde1 and Pde2) regulate the intracellular concentration of c-di-AMP. In this study, we utilized S. mitis deletion mutants of cdaA, pde1, and pde2 to analyze the role of c-di-AMP signaling in various stress responses, biofilm formation, and adhesion to eukaryotic cells. Here, we demonstrate that the Δpde1 mutant displayed a tendency toward increased susceptibility to acetic acid at pH 4.0. Deletion of cdaA increases auto-aggregation of S. mitis but reduces biofilm formation on an abiotic surface. These phenotypes are more pronounced under acidic extracellular conditions. Inactivation of pde1 or pde2 reduced the tolerance to ciprofloxacin, and UV radiation and the Δpde1 mutant was more susceptible to Triton X-100, indicating a role for c-di-AMP signaling in responses to DNA damage and cell membrane perturbation. Finally, the Δpde2 mutant displayed a tendency toward a reduced ability to adhere to oral keratinocytes. Taken together, our results indicate an important role for c-di-AMP signaling in cellular processes important for colonization of the mouth.
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Affiliation(s)
| | | | - Per Kristian Thorén Edvardsen
- Institute of Oral BiologyUniversity of OsloOsloNorway
- Present address:
Faculty of Chemistry, Biotechnology and Food ScienceNorwegian University of Life SciencesÅsNorway
| | - Roger Simm
- Institute of Oral BiologyUniversity of OsloOsloNorway
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19
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Accumulation of Succinyl Coenzyme A Perturbs the Methicillin-Resistant Staphylococcus aureus (MRSA) Succinylome and Is Associated with Increased Susceptibility to Beta-Lactam Antibiotics. mBio 2021; 12:e0053021. [PMID: 34182779 PMCID: PMC8437408 DOI: 10.1128/mbio.00530-21] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
Penicillin binding protein 2a (PBP2a)-dependent resistance to β-lactam antibiotics in methicillin-resistant Staphylococcus aureus (MRSA) is regulated by the activity of the tricarboxylic acid (TCA) cycle via a poorly understood mechanism. We report that mutations in sucC and sucD, but not other TCA cycle enzymes, negatively impact β-lactam resistance without changing PBP2a expression. Increased intracellular levels of succinyl coenzyme A (succinyl-CoA) in the sucC mutant significantly perturbed lysine succinylation in the MRSA proteome. Suppressor mutations in sucA or sucB, responsible for succinyl-CoA biosynthesis, reversed sucC mutant phenotypes. The major autolysin (Atl) was the most succinylated protein in the proteome, and increased Atl succinylation in the sucC mutant was associated with loss of autolytic activity. Although PBP2a and PBP2 were also among the most succinylated proteins in the MRSA proteome, peptidoglycan architecture and cross-linking were unchanged in the sucC mutant. These data reveal that perturbation of the MRSA succinylome impacts two interconnected cell wall phenotypes, leading to repression of autolytic activity and increased susceptibility to β-lactam antibiotics.
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20
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The Diadenylate Cyclase CdaA Is Critical for Borrelia turicatae Virulence and Physiology. Infect Immun 2021; 89:IAI.00787-20. [PMID: 33846120 PMCID: PMC8316131 DOI: 10.1128/iai.00787-20] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2020] [Accepted: 03/22/2021] [Indexed: 12/16/2022] Open
Abstract
Relapsing fever (RF), caused by spirochetes of the genus Borrelia, is a globally distributed, vector-borne disease with high prevalence in developing countries. To date, signaling pathways required for infection and virulence of RF Borrelia spirochetes are unknown. Cyclic di-AMP (c-di-AMP), synthesized by diadenylate cyclases (DACs), is a second messenger predominantly found in Gram-positive organisms that is linked to virulence and essential physiological processes. Although Borrelia is Gram-negative, it encodes one DAC (CdaA), and its importance remains undefined. To investigate the contribution of c-di-AMP signaling in the RF bacterium Borrelia turicatae, a cdaA mutant was generated. The mutant was significantly attenuated during murine infection, and genetic complementation reversed this phenotype. Because c-di-AMP is essential for viability in many bacteria, whole-genome sequencing was performed on cdaA mutants, and single-nucleotide polymorphisms identified potential suppressor mutations. Additionally, conditional mutation of cdaA confirmed that CdaA is important for normal growth and physiology. Interestingly, mutation of cdaA did not affect expression of homologs of virulence regulators whose levels are impacted by c-di-AMP signaling in the Lyme disease bacterium Borrelia burgdorferi Finally, the cdaA mutant had a significant growth defect when grown with salts, at decreased osmolarity, and without pyruvate. While the salt treatment phenotype was not reversed by genetic complementation, possibly due to suppressor mutations, growth defects at decreased osmolarity and in media lacking pyruvate could be attributed directly to cdaA inactivation. Overall, these results indicate CdaA is critical for B. turicatae pathogenesis and link c-di-AMP to osmoregulation and central metabolism in RF spirochetes.
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21
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The Many Roles of the Bacterial Second Messenger Cyclic di-AMP in Adapting to Stress Cues. J Bacteriol 2020; 203:JB.00348-20. [PMID: 32839175 DOI: 10.1128/jb.00348-20] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Bacteria respond to changes in environmental conditions through adaptation to external cues. Frequently, bacteria employ nucleotide signaling molecules to mediate a specific, rapid response. Cyclic di-AMP (c-di-AMP) was recently discovered to be a bacterial second messenger that is essential for viability in many species. In this review, we highlight recent work that has described the roles of c-di-AMP in bacterial responses to various stress conditions. These studies show that depending on the lifestyle and environmental niche of the bacterial species, the c-di-AMP signaling network results in diverse outcomes, such as regulating osmolyte transport, controlling plant attachment, or providing a checkpoint for spore formation. c-di-AMP achieves this signaling specificity through expression of different classes of synthesis and catabolic enzymes as well as receptor proteins and RNAs, which will be summarized.
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22
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Gallagher LA, Shears RK, Fingleton C, Alvarez L, Waters EM, Clarke J, Bricio-Moreno L, Campbell C, Yadav AK, Razvi F, O'Neill E, O'Neill AJ, Cava F, Fey PD, Kadioglu A, O'Gara JP. Impaired Alanine Transport or Exposure to d-Cycloserine Increases the Susceptibility of MRSA to β-lactam Antibiotics. J Infect Dis 2020; 221:1000-1016. [PMID: 31628459 DOI: 10.1093/infdis/jiz542] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2019] [Accepted: 10/14/2019] [Indexed: 12/29/2022] Open
Abstract
Prolonging the clinical effectiveness of β-lactams, which remain first-line antibiotics for many infections, is an important part of efforts to address antimicrobial resistance. We report here that inactivation of the predicted d-cycloserine (DCS) transporter gene cycA resensitized methicillin-resistant Staphylococcus aureus (MRSA) to β-lactam antibiotics. The cycA mutation also resulted in hypersusceptibility to DCS, an alanine analogue antibiotic that inhibits alanine racemase and d-alanine ligase required for d-alanine incorporation into cell wall peptidoglycan. Alanine transport was impaired in the cycA mutant, and this correlated with increased susceptibility to oxacillin and DCS. The cycA mutation or exposure to DCS were both associated with the accumulation of muropeptides with tripeptide stems lacking the terminal d-ala-d-ala and reduced peptidoglycan cross-linking, prompting us to investigate synergism between β-lactams and DCS. DCS resensitized MRSA to β-lactams in vitro and significantly enhanced MRSA eradication by oxacillin in a mouse bacteremia model. These findings reveal alanine transport as a new therapeutic target to enhance the susceptibility of MRSA to β-lactam antibiotics.
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Affiliation(s)
- Laura A Gallagher
- School of Natural Sciences, National University of Ireland, Galway, Ireland
| | - Rebecca K Shears
- Department of Clinical Infection, Microbiology and Immunology, Institute of Infection and Global Health, University of Liverpool, United Kingdom
| | - Claire Fingleton
- School of Natural Sciences, National University of Ireland, Galway, Ireland
| | - Laura Alvarez
- Molecular Infection Medicine, Sweden, Molecular Biology Department, Umeå University, Umeå, Sweden
| | - Elaine M Waters
- School of Natural Sciences, National University of Ireland, Galway, Ireland.,Department of Clinical Infection, Microbiology and Immunology, Institute of Infection and Global Health, University of Liverpool, United Kingdom
| | - Jenny Clarke
- Department of Clinical Infection, Microbiology and Immunology, Institute of Infection and Global Health, University of Liverpool, United Kingdom
| | - Laura Bricio-Moreno
- Department of Clinical Infection, Microbiology and Immunology, Institute of Infection and Global Health, University of Liverpool, United Kingdom
| | | | - Akhilesh K Yadav
- Molecular Infection Medicine, Sweden, Molecular Biology Department, Umeå University, Umeå, Sweden
| | - Fareha Razvi
- Department of Pathology and Microbiology, University of Nebraska Medical Center, Omaha, Nebraska, USA
| | - Eoghan O'Neill
- Department of Clinical Microbiology, Royal College of Surgeons in Ireland, Connolly Hospital, Dublin, Ireland
| | - Alex J O'Neill
- Antimicrobial Research Centre, School of Molecular and Cellular Biology, Faculty of Biological Sciences, University of Leeds, Leeds, United Kingdom
| | - Felipe Cava
- Molecular Infection Medicine, Sweden, Molecular Biology Department, Umeå University, Umeå, Sweden
| | - Paul D Fey
- Department of Pathology and Microbiology, University of Nebraska Medical Center, Omaha, Nebraska, USA
| | - Aras Kadioglu
- Department of Clinical Infection, Microbiology and Immunology, Institute of Infection and Global Health, University of Liverpool, United Kingdom
| | - James P O'Gara
- School of Natural Sciences, National University of Ireland, Galway, Ireland
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23
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Abstract
The second messenger molecule cyclic di-AMP (c-di-AMP) is formed by many bacteria and archaea. In many species that produce c-di-AMP, this second messenger is essential for viability on rich medium. Recent research has demonstrated that c-di-AMP binds to a large number of proteins and riboswitches, which are often involved in potassium and osmotic homeostasis. c-di-AMP becomes dispensable if the bacteria are cultivated on minimal media with low concentrations of osmotically active compounds. Thus, the essentiality of c-di-AMP does not result from an interaction with a single essential target but rather from the multilevel control of complex homeostatic processes. This review summarizes current knowledge on the homeostasis of c-di-AMP and its function(s) in the control of cellular processes.
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Affiliation(s)
- Jörg Stülke
- Department of General Microbiology, Göttingen Center for Molecular Biosciences (GZMB), Georg-August-University Göttingen, 37077 Göttingen, Germany;
| | - Larissa Krüger
- Department of General Microbiology, Göttingen Center for Molecular Biosciences (GZMB), Georg-August-University Göttingen, 37077 Göttingen, Germany;
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Aline Dias da P, Nathalia Marins de A, Gabriel Guarany de A, Robson Francisco de S, Cristiane Rodrigues G. The World of Cyclic Dinucleotides in Bacterial Behavior. Molecules 2020; 25:molecules25102462. [PMID: 32466317 PMCID: PMC7288161 DOI: 10.3390/molecules25102462] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2019] [Revised: 03/05/2020] [Accepted: 03/17/2020] [Indexed: 02/07/2023] Open
Abstract
The regulation of multiple bacterial phenotypes was found to depend on different cyclic dinucleotides (CDNs) that constitute intracellular signaling second messenger systems. Most notably, c-di-GMP, along with proteins related to its synthesis, sensing, and degradation, was identified as playing a central role in the switching from biofilm to planktonic modes of growth. Recently, this research topic has been under expansion, with the discoveries of new CDNs, novel classes of CDN receptors, and the numerous functions regulated by these molecules. In this review, we comprehensively describe the three main bacterial enzymes involved in the synthesis of c-di-GMP, c-di-AMP, and cGAMP focusing on description of their three-dimensional structures and their structural similarities with other protein families, as well as the essential residues for catalysis. The diversity of CDN receptors is described in detail along with the residues important for the interaction with the ligand. Interestingly, genomic data strongly suggest that there is a tendency for bacterial cells to use both c-di-AMP and c-di-GMP signaling networks simultaneously, raising the question of whether there is crosstalk between different signaling systems. In summary, the large amount of sequence and structural data available allows a broad view of the complexity and the importance of these CDNs in the regulation of different bacterial behaviors. Nevertheless, how cells coordinate the different CDN signaling networks to ensure adaptation to changing environmental conditions is still open for much further exploration.
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Gibhardt J, Heidemann JL, Bremenkamp R, Rosenberg J, Seifert R, Kaever V, Ficner R, Commichau FM. An extracytoplasmic protein and a moonlighting enzyme modulate synthesis of c-di-AMP in Listeria monocytogenes. Environ Microbiol 2020; 22:2771-2791. [PMID: 32250026 DOI: 10.1111/1462-2920.15008] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2020] [Revised: 03/17/2020] [Accepted: 03/31/2020] [Indexed: 01/06/2023]
Abstract
The second messenger cyclic di-AMP (c-di-AMP) is essential for growth of many bacteria because it controls osmolyte homeostasis. c-di-AMP can regulate the synthesis of potassium uptake systems in some bacteria and it also directly inhibits and activates potassium import and export systems, respectively. Therefore, c-di-AMP production and degradation have to be tightly regulated depending on the environmental osmolarity. The Gram-positive pathogen Listeria monocytogenes relies on the membrane-bound diadenylate cyclase CdaA for c-di-AMP production and degrades the nucleotide with two phosphodiesterases. While the enzymes producing and degrading the dinucleotide have been reasonably well examined, the regulation of c-di-AMP production is not well understood yet. Here we demonstrate that the extracytoplasmic regulator CdaR interacts with CdaA via its transmembrane helix to modulate c-di-AMP production. Moreover, we show that the phosphoglucosamine mutase GlmM forms a complex with CdaA and inhibits the diadenylate cyclase activity in vitro. We also found that GlmM inhibits c-di-AMP production in L. monocytogenes when the bacteria encounter osmotic stress. Thus, GlmM is the major factor controlling the activity of CdaA in vivo. GlmM can be assigned to the class of moonlighting proteins because it is active in metabolism and adjusts the cellular turgor depending on environmental osmolarity.
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Affiliation(s)
- Johannes Gibhardt
- Department of General Microbiology, Institute for Microbiology and Genetics, University of Goettingen, 37077, Göttingen, Germany.,FG Synthetic Microbiology, Institute for Biotechnology, BTU Cottbus-Senftenberg, 01968, Senftenberg, Germany
| | - Jana L Heidemann
- Department of Molecular Structural Biology, Institute for Microbiology and Genetics, GZMB, University of Goettingen, 37077, Göttingen, Germany
| | - Rica Bremenkamp
- Department of General Microbiology, Institute for Microbiology and Genetics, University of Goettingen, 37077, Göttingen, Germany
| | - Jonathan Rosenberg
- Department of General Microbiology, Institute for Microbiology and Genetics, University of Goettingen, 37077, Göttingen, Germany
| | - Roland Seifert
- Institute of Pharmacology & Research Core Unit Metabolomics, Hannover Medical School, Hannover, Germany
| | - Volkhard Kaever
- Institute of Pharmacology & Research Core Unit Metabolomics, Hannover Medical School, Hannover, Germany
| | - Ralf Ficner
- Department of Molecular Structural Biology, Institute for Microbiology and Genetics, GZMB, University of Goettingen, 37077, Göttingen, Germany
| | - Fabian M Commichau
- FG Synthetic Microbiology, Institute for Biotechnology, BTU Cottbus-Senftenberg, 01968, Senftenberg, Germany
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Genetic Determinants Enabling Medium-Dependent Adaptation to Nafcillin in Methicillin-Resistant Staphylococcus aureus. mSystems 2020; 5:5/2/e00828-19. [PMID: 32234776 PMCID: PMC7112963 DOI: 10.1128/msystems.00828-19] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Antimicrobial susceptibility testing standards driving clinical decision-making have centered around the use of cation-adjusted Mueller-Hinton broth (CA-MHB) as the medium with the notion of supporting bacterial growth, without consideration of recapitulating the in vivo environment. However, it is increasingly recognized that various medium conditions have tremendous influence on antimicrobial activity, which in turn may have major implications on the ability of in vitro susceptibility assays to predict antibiotic activity in vivo. To elucidate differential growth optimization and antibiotic resistance mechanisms, adaptive laboratory evolution was performed in the presence or absence of the antibiotic nafcillin with methicillin-resistant Staphylococcus aureus (MRSA) TCH1516 in either (i) CA-MHB, a traditional bacteriological nutritionally rich medium, or (ii) Roswell Park Memorial Institute (RPMI), a medium more reflective of the in vivo host environment. Medium adaptation analysis showed an increase in growth rate in RPMI, but not CA-MHB, with mutations in apt, adenine phosphoribosyltransferase, and the manganese transporter subunit, mntA, occurring reproducibly in parallel replicate evolutions. The medium-adapted strains showed no virulence attenuation. Continuous exposure of medium-adapted strains to increasing concentrations of nafcillin led to medium-specific evolutionary strategies. Key reproducibly occurring mutations were specific for nafcillin adaptation in each medium type and did not confer resistance in the other medium environment. Only the vraRST operon, a regulator of membrane- and cell wall-related genes, showed mutations in both CA-MHB- and RPMI-evolved strains. Collectively, these results demonstrate the medium-specific genetic adaptive responses of MRSA and establish adaptive laboratory evolution as a platform to study clinically relevant resistance mechanisms.IMPORTANCE The ability of pathogens such as Staphylococcus aureus to evolve resistance to antibiotics used in the treatment of infections has been an important concern in the last decades. Resistant acquisition usually translates into treatment failure and puts patients at risk of unfavorable outcomes. Furthermore, the laboratory testing of antibiotic resistance does not account for the different environment the bacteria experiences within the human body, leading to results that do not translate into the clinic. In this study, we forced methicillin-resistant S. aureus to develop nafcillin resistance in two different environments, a laboratory environment and a physiologically more relevant environment. This allowed us to identify genetic changes that led to nafcillin resistance under both conditions. We concluded that not only does the environment dictate the evolutionary strategy of S. aureus to nafcillin but also that the evolutionary strategy is specific to that given environment.
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Leonard A, Möhlis K, Schlüter R, Taylor E, Lalk M, Methling K. Exploring metabolic adaptation of Streptococcus pneumoniae to antibiotics. J Antibiot (Tokyo) 2020; 73:441-454. [PMID: 32210362 PMCID: PMC7292801 DOI: 10.1038/s41429-020-0296-3] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2019] [Revised: 01/31/2020] [Accepted: 02/09/2020] [Indexed: 02/07/2023]
Abstract
The Gram-positive bacterium Streptococcus pneumoniae is one of the common causes of community acquired pneumonia, meningitis, and otitis media. Analyzing the metabolic adaptation toward environmental stress conditions improves our understanding of its pathophysiology and its dependency on host-derived nutrients. In this study, extra- and intracellular metabolic profiles were evaluated to investigate the impact of antimicrobial compounds targeting different pathways of the metabolome of S. pneumoniae TIGR4Δcps. For the metabolomics approach, we analyzed the complex variety of metabolites by using 1H NMR, HPLC-MS, and GC–MS as different analytical techniques. Through this combination, we detected nearly 120 metabolites. For each antimicrobial compound, individual metabolic effects were detected that often comprised global biosynthetic pathways. Cefotaxime altered amino acids metabolism and carbon metabolism. The purine and pyrimidine metabolic pathways were mostly affected by moxifloxacin treatment. The combination of cefotaxime and azithromycin intensified the stress response compared with the use of the single antibiotic. However, we observed that three cell wall metabolites were altered only by treatment with the combination of the two antibiotics. Only moxifloxacin stress-induced alternation in CDP-ribitol concentration. Teixobactin-Arg10 resulted in global changes of pneumococcal metabolism. To meet the growing requirements for new antibiotics, our metabolomics approach has shown to be a promising complement to other OMICs investigations allowing insights into the mode of action of novel antimicrobial compounds.
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Affiliation(s)
- Anne Leonard
- Institute for Biochemistry, Metabolomics, University of Greifswald, Felix-Hausdorff-Str. 4, 17489, Greifswald, Germany
| | - Kevin Möhlis
- Institute for Biochemistry, Metabolomics, University of Greifswald, Felix-Hausdorff-Str. 4, 17489, Greifswald, Germany
| | - Rabea Schlüter
- Imaging Center of the Department of Biology, University of Greifswald, F.-L-Jahn-Str. 15, 17489, Greifswald, Germany
| | - Edward Taylor
- University of Lincoln, School of Life Sciences, Green Lane, LN67DL, Lincoln, England, United Kingdom
| | - Michael Lalk
- Institute for Biochemistry, Metabolomics, University of Greifswald, Felix-Hausdorff-Str. 4, 17489, Greifswald, Germany
| | - Karen Methling
- Institute for Biochemistry, Metabolomics, University of Greifswald, Felix-Hausdorff-Str. 4, 17489, Greifswald, Germany.
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Gostev V, Sopova J, Kalinogorskaya O, Tsvetkova I, Lobzin Y, Klotchenko S, Sidorenko S. In Vitro Ceftaroline Resistance Selection of Methicillin-Resistant Staphylococcus aureus Involves Different Genetic Pathways. Microb Drug Resist 2019; 25:1401-1409. [PMID: 31329022 DOI: 10.1089/mdr.2019.0130] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
The pathways in the development of ceftaroline resistance of methicillin-resistant Staphylococcus aureus (MRSA) isolates belonging to the ST8, ST239, and ST228 were evaluated. Ceftaroline-resistant derivatives were isolated through selection during 40 passages. Ceftaroline MIC measurements and whole-genome sequencing were performed after 5, 20, and 40 passages. In two ST8 derivative isolates, ceftaroline MIC increased up to 128 mg/L. Mutations were acquired in gdpP and graS in one isolate after 20 passages and in gdpP in another after 40 passages. MIC for two ST239 derivatives increased to 128 mg/L. Substitutions in Pbp4 and polymorphisms in the upstream region of pbp4 were identified in both derivatives after 40 passages. In one isolate, additional mutation in gdpP and deletion in graR were detected. In an ST228 derivative, MIC increased to 32 mg/L with one mutation in penicillin-binding protein 2a (Y446N) detected after five passages and a second (E447K) after 20 passages. Three pathways in the development of ceftaroline resistance were identified. For ST8 and ST239 derivatives mutations were detected in gdpP and pbp4, respectively, whereas in ST228 - in mecA. Most derivatives harbored additional mutations whose potential role in the development of resistance has not been determined.
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Affiliation(s)
- Vladimir Gostev
- Department of Medical Microbiology and Molecular Epidemiology, Pediatric Research and Clinical Center for Infectious Diseases, Saint Petersburg, Russia
- Department of Medical Microbiology, North-Western State Medical University named after I.I. Mechnikov, Saint Petersburg, Russia
| | - Julia Sopova
- Laboratory of Genetic Models of Human Diseases, Saint Petersburg Branch of Vavilov Institute of General Genetics, Saint Petersburg, Russia
- Department of Genetics and Biotechnology, Saint Petersburg State University, Saint Petersburg, Russia
| | - Olga Kalinogorskaya
- Department of Medical Microbiology and Molecular Epidemiology, Pediatric Research and Clinical Center for Infectious Diseases, Saint Petersburg, Russia
| | - Irina Tsvetkova
- Department of Medical Microbiology and Molecular Epidemiology, Pediatric Research and Clinical Center for Infectious Diseases, Saint Petersburg, Russia
| | - Yuri Lobzin
- Department of Medical Microbiology and Molecular Epidemiology, Pediatric Research and Clinical Center for Infectious Diseases, Saint Petersburg, Russia
- Department of Medical Microbiology, North-Western State Medical University named after I.I. Mechnikov, Saint Petersburg, Russia
| | - Sergey Klotchenko
- Division of Viral Molecular Biology, Smorodintsev Research Institute of Influenza, Saint Petersburg, Russia
| | - Sergey Sidorenko
- Department of Medical Microbiology and Molecular Epidemiology, Pediatric Research and Clinical Center for Infectious Diseases, Saint Petersburg, Russia
- Department of Medical Microbiology, North-Western State Medical University named after I.I. Mechnikov, Saint Petersburg, Russia
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29
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Hofstraat SH, Götz HM, van Dam AP, van der Sande MA, van Benthem BH. Trends and determinants of antimicrobial susceptibility of Neisseria gonorrhoeae in the Netherlands, 2007 to 2015. ACTA ACUST UNITED AC 2019; 23. [PMID: 30205870 PMCID: PMC6134804 DOI: 10.2807/1560-7917.es.2018.23.36.1700565] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
Neisseria gonorrhoeae antibiotic resistance surveillance is important to maintain adequate treatment. We analysed 2007–15 data from the Gonococcal Resistance to Antimicrobials Surveillance (GRAS), which currently includes 19 of 25 sexually transmitted infection (STI) centres in the Netherlands. Methods: From each patient with a gonorrhoea culture, the minimum inhibitory concentration (MIC) for several antibiotics was determined. Time trends were assessed by geometric means and linear regression of logarithmic MIC. Determinants for decreased susceptibility to ceftriaxone (MIC > 0.032 mg/L) and resistance to cefotaxime (MIC > 0.125 mg/L) and azithromycin (MIC > 0.5 mg/L) were assessed using stratified logistic regression. Results: 11,768 isolates were analysed. No ceftriaxone resistance was found. In 2015, 27 of 1,425 isolates (1.9%) were resistant to cefotaxime and 176 of 1,623 (10.9%) to azithromycin. Ceftriaxone susceptibility showed no trend (p = 0.96) during the study period, but cefotaxime MIC decreased (p < 0.0001) and azithromycin MIC increased (p < 0.0001) significantly. Concerning ceftriaxone, isolates of men who have sex with men (MSM) from 2013 (p = 0.0005) and 2014 (p = 0.0004) were significantly associated with decreased susceptibility. Significant determinants for cefotaxime resistance were having ≥ 6 partners for women (p = 0.0006). For azithromycin,isolates from MSM collected in 2012 (p = 0.0035), 2013 (p = 0.012), and 2014 (p = 0.013), or from non-Dutch (p < 0.0001) or older (≥ 35 years; p = 0.01) MSM were significantly associated with susceptibility. Resistance in heterosexual men was significantly associated with being ≥ 25 years-old (p = 0.0049) or having 3–5 partners (p = 0.01). Conclusions: No ceftriaxone resistance was found, but azithromycin MIC increased in 2007–15. Resistance determinants could help with focused intervention strategies.
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Affiliation(s)
- Sanne Hi Hofstraat
- National Institute for Public Health and the Environment (RIVM), Centre for Infectious Disease Control, Bilthoven, the Netherlands
| | - Hannelore M Götz
- Department of Infectious Disease Control, Municipal Public Health Service Rotterdam-Rijnmond, Rotterdam, the Netherlands.,National Institute for Public Health and the Environment (RIVM), Centre for Infectious Disease Control, Bilthoven, the Netherlands
| | - Alje P van Dam
- Public Health Laboratory, Amsterdam Health Service, Amsterdam, the Netherlands
| | - Marianne Ab van der Sande
- Department of Public Health, Institute of Tropical Medicine, Antwerp, Belgium.,Julius Centre for Health Sciences and Primary Care, University Medical Centre, Utrecht, the Netherlands.,National Institute for Public Health and the Environment (RIVM), Centre for Infectious Disease Control, Bilthoven, the Netherlands
| | - Birgit Hb van Benthem
- National Institute for Public Health and the Environment (RIVM), Centre for Infectious Disease Control, Bilthoven, the Netherlands
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(p)ppGpp and CodY Promote Enterococcus faecalis Virulence in a Murine Model of Catheter-Associated Urinary Tract Infection. mSphere 2019; 4:4/4/e00392-19. [PMID: 31341072 PMCID: PMC6656871 DOI: 10.1128/msphere.00392-19] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Catheter-associated urinary tract infections (CAUTIs) are one of the most frequent types of infection found in the hospital setting that can develop into serious and potentially fatal bloodstream infections. One of the infectious agents that frequently causes complicated CAUTI is the bacterium Enterococcus faecalis, a leading cause of hospital-acquired infections that are often difficult to treat due to the exceptional multidrug resistance of some isolates. Understanding the mechanisms by which E. faecalis causes CAUTI will aid in the discovery of new druggable targets to treat these infections. In this study, we report the importance of two nutrient-sensing bacterial regulators, named (p)ppGpp and CodY, for the ability of E. faecalis to infect the catheterized bladder of mice. In Firmicutes, the nutrient-sensing regulators (p)ppGpp, the effector molecule of the stringent response, and CodY work in tandem to maintain bacterial fitness during infection. Here, we tested (p)ppGpp and codY mutant strains of Enterococcus faecalis in a catheter-associated urinary tract infection (CAUTI) mouse model and used global transcriptional analysis to investigate the relationship of (p)ppGpp and CodY. The absence of (p)ppGpp or single inactivation of codY led to lower bacterial loads in catheterized bladders and diminished biofilm formation on fibrinogen-coated surfaces under in vitro and in vivo conditions. Single inactivation of the bifunctional (p)ppGpp synthetase/hydrolase rel did not affect virulence, supporting previous evidence that the association of (p)ppGpp with enterococcal virulence is not dependent on the activation of the stringent response. Inactivation of codY in the (p)ppGpp0 strain restored E. faecalis virulence in the CAUTI model as well as the ability to form biofilms in vitro. Transcriptome analysis revealed that inactivation of codY restores, for the most part, the dysregulated metabolism of (p)ppGpp0 cells. While a clear linkage between (p)ppGpp and CodY with expression of virulence factors could not be established, targeted transcriptional analysis indicates that a possible association between (p)ppGpp and c-di-AMP signaling pathways in response to the conditions found in the bladder may play a role in enterococcal CAUTI. Collectively, data from this study identify the (p)ppGpp-CodY network as an important contributor to enterococcal virulence in catheterized mouse bladder and support that basal (p)ppGpp pools and CodY promote virulence through maintenance of a balanced metabolism under adverse conditions. IMPORTANCE Catheter-associated urinary tract infections (CAUTIs) are one of the most frequent types of infection found in the hospital setting that can develop into serious and potentially fatal bloodstream infections. One of the infectious agents that frequently causes complicated CAUTI is the bacterium Enterococcus faecalis, a leading cause of hospital-acquired infections that are often difficult to treat due to the exceptional multidrug resistance of some isolates. Understanding the mechanisms by which E. faecalis causes CAUTI will aid in the discovery of new druggable targets to treat these infections. In this study, we report the importance of two nutrient-sensing bacterial regulators, named (p)ppGpp and CodY, for the ability of E. faecalis to infect the catheterized bladder of mice.
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Tosi T, Hoshiga F, Millership C, Singh R, Eldrid C, Patin D, Mengin-Lecreulx D, Thalassinos K, Freemont P, Gründling A. Inhibition of the Staphylococcus aureus c-di-AMP cyclase DacA by direct interaction with the phosphoglucosamine mutase GlmM. PLoS Pathog 2019; 15:e1007537. [PMID: 30668586 PMCID: PMC6368335 DOI: 10.1371/journal.ppat.1007537] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2018] [Revised: 02/08/2019] [Accepted: 12/18/2018] [Indexed: 02/05/2023] Open
Abstract
c-di-AMP is an important second messenger molecule that plays a pivotal role in regulating fundamental cellular processes, including osmotic and cell wall homeostasis in many Gram-positive organisms. In the opportunistic human pathogen Staphylococcus aureus, c-di-AMP is produced by the membrane-anchored DacA enzyme. Inactivation of this enzyme leads to a growth arrest under standard laboratory growth conditions and a re-sensitization of methicillin-resistant S. aureus (MRSA) strains to ß-lactam antibiotics. The gene coding for DacA is part of the conserved three-gene dacA/ybbR/glmM operon that also encodes the proposed DacA regulator YbbR and the essential phosphoglucosamine mutase GlmM, which is required for the production of glucosamine-1-phosphate, an early intermediate of peptidoglycan synthesis. These three proteins are thought to form a complex in vivo and, in this manner, help to fine-tune the cellular c-di-AMP levels. To further characterize this important regulatory complex, we conducted a comprehensive structural and functional analysis of the S. aureus DacA and GlmM enzymes by determining the structures of the S. aureus GlmM enzyme and the catalytic domain of DacA. Both proteins were found to be dimers in solution as well as in the crystal structures. Further site-directed mutagenesis, structural and enzymatic studies showed that multiple DacA dimers need to interact for enzymatic activity. We also show that DacA and GlmM form a stable complex in vitro and that S. aureus GlmM, but not Escherichia coli or Pseudomonas aeruginosa GlmM, acts as a strong inhibitor of DacA function without the requirement of any additional cellular factor. Based on Small Angle X-ray Scattering (SAXS) data, a model of the complex revealed that GlmM likely inhibits DacA by masking the active site of the cyclase and preventing higher oligomer formation. Together these results provide an important mechanistic insight into how c-di-AMP production can be regulated in the cell.
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Affiliation(s)
- Tommaso Tosi
- Section of Microbiology and MRC Centre for Molecular Bacteriology and Infection, Imperial College London, London, United Kingdom
| | - Fumiya Hoshiga
- Section of Microbiology and MRC Centre for Molecular Bacteriology and Infection, Imperial College London, London, United Kingdom
| | - Charlotte Millership
- Section of Microbiology and MRC Centre for Molecular Bacteriology and Infection, Imperial College London, London, United Kingdom
| | - Rahul Singh
- Section of Microbiology and MRC Centre for Molecular Bacteriology and Infection, Imperial College London, London, United Kingdom
| | - Charles Eldrid
- Institute of Structural and Molecular Biology, Birkbeck College, University of London, Malet Street, London, United Kingdom
- Institute of Structural and Molecular Biology, Division of Biosciences, University College London, London, United Kingdom
| | - Delphine Patin
- Institute for Integrative Biology of the Cell, CEA, CNRS, Univ Paris-Sud and Université Paris-Saclay, Gif-sur-Yvette, France
| | - Dominique Mengin-Lecreulx
- Institute for Integrative Biology of the Cell, CEA, CNRS, Univ Paris-Sud and Université Paris-Saclay, Gif-sur-Yvette, France
| | - Konstantinos Thalassinos
- Institute of Structural and Molecular Biology, Birkbeck College, University of London, Malet Street, London, United Kingdom
- Institute of Structural and Molecular Biology, Division of Biosciences, University College London, London, United Kingdom
| | - Paul Freemont
- Section of Structural Biology, Department of Medicine, Imperial College London, London, United Kingdom
| | - Angelika Gründling
- Section of Microbiology and MRC Centre for Molecular Bacteriology and Infection, Imperial College London, London, United Kingdom
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32
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Agostoni M, Logan-Jackson AR, Heinz ER, Severin GB, Bruger EL, Waters CM, Montgomery BL. Homeostasis of Second Messenger Cyclic-di-AMP Is Critical for Cyanobacterial Fitness and Acclimation to Abiotic Stress. Front Microbiol 2018; 9:1121. [PMID: 29896182 PMCID: PMC5986932 DOI: 10.3389/fmicb.2018.01121] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2018] [Accepted: 05/11/2018] [Indexed: 12/11/2022] Open
Abstract
Second messengers are intracellular molecules regulated by external stimuli known as first messengers that are used for rapid organismal responses to dynamic environmental changes. Cyclic di-AMP (c-di-AMP) is a relatively newly discovered second messenger implicated in cell wall homeostasis in many pathogenic bacteria. C-di-AMP is synthesized from ATP by diadenylyl cyclases (DAC) and degraded by specific c-di-AMP phosphodiesterases (PDE). C-di-AMP DACs and PDEs are present in all sequenced cyanobacteria, suggesting roles for c-di-AMP in the physiology and/or development of these organisms. Despite conservation of these genes across numerous cyanobacteria, the functional roles of c-di-AMP in cyanobacteria have not been well-investigated. In a unique feature of cyanobacteria, phylogenetic analysis indicated that the broadly conserved DAC, related to CdaA/DacA, is always co-associated in an operon with genes critical for controlling cell wall synthesis. To investigate phenotypes regulated by c-di-AMP in cyanobacteria, we overexpressed native DAC (sll0505) and c-di-AMP PDE (slr0104) genes in the cyanobacterium Synechocystis sp. PCC 6803 (hereafter Synechocystis) to increase and decrease intracellular c-di-AMP levels, respectively. DAC- and PDE-overexpression strains, showed abnormal aggregation phenotypes, suggesting functional roles for regulating c-di-AMP homeostasis in vivo. As c-di-AMP may be implicated in osmotic responses in cyanobacteria, we tested whether sorbitol and NaCl stresses impacted expression of sll0505 and slr0104 or intracellular c-di-AMP levels in Synechocystis. Additionally, to determine the range of cyanobacteria in which c-di-AMP may function, we assessed c-di-AMP levels in two unicellular cyanobacteria, i.e., Synechocystis and Synechococcus elongatus PCC 7942, and two filamentous cyanobacteria, i.e., Fremyella diplosiphon and Anabaena sp. PCC 7120. C-di-AMP levels responded differently to abiotic stress signals in distinct cyanobacteria strains, whereas salt stress uniformly impacted another second messenger cyclic di-GMP in cyanobacteria. Together, these results suggest regulation of c-di-AMP homeostasis in cyanobacteria and implicate a role for the second messenger in maintaining cellular fitness in response to abiotic stress.
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Affiliation(s)
- Marco Agostoni
- Cell and Molecular Biology Graduate Program, Michigan State University, East Lansing, MI, United States.,Department of Energy Plant Research Laboratory, Michigan State University, East Lansing, MI, United States
| | - Alshaé R Logan-Jackson
- Department of Energy Plant Research Laboratory, Michigan State University, East Lansing, MI, United States.,Department of Microbiology and Molecular Genetics, Michigan State University, East Lansing, MI, United States
| | - Emily R Heinz
- Department of Energy Plant Research Laboratory, Michigan State University, East Lansing, MI, United States
| | - Geoffrey B Severin
- Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, MI, United States
| | - Eric L Bruger
- Department of Microbiology and Molecular Genetics, Michigan State University, East Lansing, MI, United States
| | - Christopher M Waters
- Cell and Molecular Biology Graduate Program, Michigan State University, East Lansing, MI, United States.,Department of Microbiology and Molecular Genetics, Michigan State University, East Lansing, MI, United States
| | - Beronda L Montgomery
- Cell and Molecular Biology Graduate Program, Michigan State University, East Lansing, MI, United States.,Department of Energy Plant Research Laboratory, Michigan State University, East Lansing, MI, United States.,Department of Microbiology and Molecular Genetics, Michigan State University, East Lansing, MI, United States.,Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, MI, United States
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Stress Suppressor Screening Leads to Detection of Regulation of Cyclic di-AMP Homeostasis by a Trk Family Effector Protein in Streptococcus pneumoniae. J Bacteriol 2018; 200:JB.00045-18. [PMID: 29483167 DOI: 10.1128/jb.00045-18] [Citation(s) in RCA: 31] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2018] [Accepted: 02/21/2018] [Indexed: 02/07/2023] Open
Abstract
Cyclic di-AMP (c-di-AMP) is a newly discovered bacterial second messenger. However, regulation of c-di-AMP homeostasis is poorly understood. In Streptococcus pneumoniae, a sole diadenylate cyclase, CdaA, produces c-di-AMP and two phosphodiesterases, Pde1 and Pde2, cleave the signaling dinucleotide. To expand our knowledge of the pneumococcal c-di-AMP signaling network, we performed whole-genome sequencing of Δpde1 Δpde2 heat shock suppressors. In addition to their effects on surviving heat shock, these suppressor mutations restored general stress resistance and improved growth in rich medium. Mutations in CdaA or in the potassium transporter TrkH paired with an insertion leading to a frameshift at the C terminus of CdaA significantly reduced c-di-AMP levels. These observations indicate that the elevated c-di-AMP levels in the Δpde1 Δpde2 mutant enhance susceptibility of S. pneumoniae to the stress conditions. Interestingly, we have previously shown that TrkH complexes with a Trk family c-di-AMP-binding protein, CabP, to mediate potassium uptake. In this study, we found that deletion of cabP significantly reduced pneumococcal c-di-AMP levels. This is the first observation that a c-di-AMP effector protein modulates bacterial c-di-AMP homeostasis.IMPORTANCE Second messengers, including c-di-AMP, are prevalent among bacterial species. In S. pneumoniae, c-di-AMP phosphodiesterase-encoding gene null mutants are attenuated during mouse models of infection, but the role of c-di-AMP signaling in pneumococcal pathogenesis is enigmatic. In this work, we found that heat shock suppressor mutations converge on undermining c-di-AMP toxicity by changing intracellular c-di-AMP concentrations. These mutations improve the growth and restore the stress response generally in c-di-AMP phosphodiesterase-deficient pneumococci, thereby demonstrating the essentiality for tight regulation of c-di-AMP homeostasis in order to respond to stress. Likewise, this work demonstrates that a c-di-AMP effector protein, CabP, affects c-di-AMP homeostasis, which provides new perception into c-di-AMP regulation. This study has implications for c-di-AMP-producing bacteria since many species contain CabP homologs.
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Zeden MS, Schuster CF, Bowman L, Zhong Q, Williams HD, Gründling A. Cyclic di-adenosine monophosphate (c-di-AMP) is required for osmotic regulation in Staphylococcus aureus but dispensable for viability in anaerobic conditions. J Biol Chem 2018; 293:3180-3200. [PMID: 29326168 PMCID: PMC5836111 DOI: 10.1074/jbc.m117.818716] [Citation(s) in RCA: 64] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2017] [Revised: 01/03/2018] [Indexed: 01/15/2023] Open
Abstract
Cyclic di-adenosine monophosphate (c-di-AMP) is a recently discovered signaling molecule important for the survival of Firmicutes, a large bacterial group that includes notable pathogens such as Staphylococcus aureus However, the exact role of this molecule has not been identified. dacA, the S. aureus gene encoding the diadenylate cyclase enzyme required for c-di-AMP production, cannot be deleted when bacterial cells are grown in rich medium, indicating that c-di-AMP is required for growth in this condition. Here, we report that an S. aureus dacA mutant can be generated in chemically defined medium. Consistent with previous findings, this mutant had a severe growth defect when cultured in rich medium. Using this growth defect in rich medium, we selected for suppressor strains with improved growth to identify c-di-AMP-requiring pathways. Mutations bypassing the essentiality of dacA were identified in alsT and opuD, encoding a predicted amino acid and osmolyte transporter, the latter of which we show here to be the main glycine betaine-uptake system in S. aureus. Inactivation of these transporters likely prevents the excessive osmolyte and amino acid accumulation in the cell, providing further evidence for a key role of c-di-AMP in osmotic regulation. Suppressor mutations were also obtained in hepS, hemB, ctaA, and qoxB, coding proteins required for respiration. Furthermore, we show that dacA is dispensable for growth in anaerobic conditions. Together, these findings reveal an essential role for the c-di-AMP signaling network in aerobic, but not anaerobic, respiration in S. aureus.
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Affiliation(s)
- Merve S Zeden
- From the Section of Microbiology and Medical Research Council Centre for Molecular Bacteriology and Infection and
| | - Christopher F Schuster
- From the Section of Microbiology and Medical Research Council Centre for Molecular Bacteriology and Infection and
| | - Lisa Bowman
- From the Section of Microbiology and Medical Research Council Centre for Molecular Bacteriology and Infection and
| | - Qiyun Zhong
- From the Section of Microbiology and Medical Research Council Centre for Molecular Bacteriology and Infection and
| | - Huw D Williams
- Department of Life Sciences, Imperial College London, London SW7 2AZ, United Kingdom
| | - Angelika Gründling
- From the Section of Microbiology and Medical Research Council Centre for Molecular Bacteriology and Infection and
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Luciferase Reporter Gene System to Detect Cell Wall Stress Stimulon Induction in Staphylococcus aureus. Methods Mol Biol 2018; 1440:139-50. [PMID: 27311670 DOI: 10.1007/978-1-4939-3676-2_11] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/08/2023]
Abstract
Luciferase reporter gene fusions provide an extremely rapid and sensitive tool for measuring the induction or repression of stress responses in bacteria. Staphylococcus aureus activates the expression of a cell wall stress stimulon (CWSS) in response to the inhibition or disruption of cell wall synthesis. The highly sensitive promoter-reporter gene fusion construct psas016 p-luc+ can be used to quantify and compare any changes in CWSS expression levels and induction kinetics. Potential uses of this system include identifying and characterizing novel cell wall-targeting antibacterial agents, identifying genomic loci influencing cell envelope synthesis and detecting changes in CWSS expression that could be linked to decreased antibiotic susceptibility profiles in clinical isolates.
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Sekyere JO, Asante J. Emerging mechanisms of antimicrobial resistance in bacteria and fungi: advances in the era of genomics. Future Microbiol 2018; 13:241-262. [PMID: 29319341 DOI: 10.2217/fmb-2017-0172] [Citation(s) in RCA: 59] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
Bacteria and fungi continue to develop new ways to adapt and survive the lethal or biostatic effects of antimicrobials through myriad mechanisms. Novel antibiotic resistance genes such as lsa(C), erm(44), VCC-1, mcr-1, mcr-2, mcr-3, mcr-4, bla KLUC-3 and bla KLUC-4 were discovered through comparative genomics and further functional studies. As well, mutations in genes that hitherto were unknown to confer resistance to antimicrobials, such as trm, PP2C, rpsJ, HSC82, FKS2 and Rv2887, were shown by genomics and transcomplementation assays to mediate antimicrobial resistance in Acinetobacter baumannii, Staphylococcus aureus, Enterococcus faecium, Saccharomyces cerevisae, Candida glabrata and Mycobacterium tuberculosis, respectively. Thus, genomics, transcriptomics and metagenomics, coupled with functional studies are the future of antimicrobial resistance research and novel drug discovery or design.
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Affiliation(s)
- John Osei Sekyere
- Faculty of Pharmacy & Pharmaceutical Sciences, Kwame Nkrumah University of Science & Technology, Kumasi, Ghana
| | - Jonathan Asante
- Faculty of Pharmacy & Pharmaceutical Sciences, Kwame Nkrumah University of Science & Technology, Kumasi, Ghana
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Drexler DJ, Müller M, Rojas-Cordova CA, Bandera AM, Witte G. Structural and Biophysical Analysis of the Soluble DHH/DHHA1-Type Phosphodiesterase TM1595 from Thermotoga maritima. Structure 2017; 25:1887-1897.e4. [PMID: 29107484 DOI: 10.1016/j.str.2017.10.001] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2017] [Revised: 09/07/2017] [Accepted: 09/29/2017] [Indexed: 11/26/2022]
Abstract
The concentration of messenger molecules in bacterial cells needs to be tightly regulated. This can be achieved by either controlling the synthesis rate, degradation, or export by specific transporters, respectively. The regulation of the essential second messenger c-di-AMP is achieved by modulation of the diadenylate cyclase activity as well as by specific phosphodiesterases that hydrolyze c-di-AMP in the cell. We provide here structural and biochemical data on the DHH-type phosphodiesterase TmPDE (TM1595) from Thermotoga maritima. Our analysis shows that TmPDE is preferentially degrading linear dinucleotides, such as 5'-pApA, 5'-pGpG, and 5'-pApG, compared with cyclic dinucleotide substrates. The high-resolution structural data provided here describe all steps of the PDE reaction: the ligand-free enzyme, two substrate-bound states, and three post-reaction states. We can furthermore show that Pde2 from Streptococcus pneumoniae shares both structural features and substrate specificity based on small-angle X-ray scattering data and biochemical assays.
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Affiliation(s)
- David Jan Drexler
- Gene Center and Department of Biochemistry, Ludwig-Maximilians-Universität München, Feodor-Lynen-Str. 25, 81377 Munich, Germany
| | - Martina Müller
- Gene Center and Department of Biochemistry, Ludwig-Maximilians-Universität München, Feodor-Lynen-Str. 25, 81377 Munich, Germany
| | - Carlos Alberto Rojas-Cordova
- Gene Center and Department of Biochemistry, Ludwig-Maximilians-Universität München, Feodor-Lynen-Str. 25, 81377 Munich, Germany
| | - Adrian Maurice Bandera
- Gene Center and Department of Biochemistry, Ludwig-Maximilians-Universität München, Feodor-Lynen-Str. 25, 81377 Munich, Germany
| | - Gregor Witte
- Gene Center and Department of Biochemistry, Ludwig-Maximilians-Universität München, Feodor-Lynen-Str. 25, 81377 Munich, Germany.
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A Delicate Connection: c-di-AMP Affects Cell Integrity by Controlling Osmolyte Transport. Trends Microbiol 2017; 26:175-185. [PMID: 28965724 DOI: 10.1016/j.tim.2017.09.003] [Citation(s) in RCA: 75] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2017] [Revised: 08/16/2017] [Accepted: 09/08/2017] [Indexed: 12/15/2022]
Abstract
Bacteria use second-messenger molecules to adapt to their environment. Several second messengers, among them cyclic di-AMP (c-di-AMP), have been discovered and intensively studied. Interestingly, c-di-AMP is essential for growth of Gram-positive bacteria such as Bacillus subtilis, Listeria monocytogenes, and Staphylococcus aureus. Many studies demonstrated that perturbation of c-di-AMP metabolism affects the integrity of the bacterial cell envelope. Therefore, it has been assumed that the nucleotide is essential for proper cell envelope synthesis. In this Opinion paper, we propose that the cell envelope phenotypes caused by perturbations of c-di-AMP metabolism can be interpreted differently: c-di-AMP might indirectly control cell envelope integrity by modulating the turgor, a physical variable that needs to be tightly adjusted. We also discuss open questions related to c-di-AMP metabolism that need to be urgently addressed by future studies.
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Tandem Amplification of the Staphylococcal Cassette Chromosome mec Element Can Drive High-Level Methicillin Resistance in Methicillin-Resistant Staphylococcus aureus. Antimicrob Agents Chemother 2017; 61:AAC.00869-17. [PMID: 28717043 DOI: 10.1128/aac.00869-17] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2017] [Accepted: 07/08/2017] [Indexed: 11/20/2022] Open
Abstract
Hospital-associated methicillin-resistant Staphylococcus aureus (MRSA) strains typically express high-level, homogeneous (HoR) β-lactam resistance, whereas community-associated MRSA (CA-MRSA) more commonly express low-level heterogeneous (HeR) resistance. Expression of the HoR phenotype typically requires both increased expression of the mecA gene, carried on the staphylococcal cassette chromosome mec element (SCCmec), and additional mutational event(s) elsewhere on the chromosome. Here the oxacillin concentration in a chemostat culture of the CA-MRSA strain USA300 was increased from 8 μg/ml to 130 μg/ml over 13 days to isolate highly oxacillin-resistant derivatives. A stable, small-colony variant, designated HoR34, which had become established in the chemostat culture was found to have acquired mutations in gdpP, clpX, guaA, and camS Closer inspection of the genome sequence data further revealed that reads covering SCCmec were ∼10 times overrepresented compared to other parts of the chromosome. Quantitative PCR (qPCR) confirmed >10-fold-higher levels of mecA DNA on the HoR34 chromosome, and MinION genome sequencing verified the presence of 10 tandem repeats of the SCCmec element. qPCR further demonstrated that subculture of HoR34 in various concentrations of oxacillin (0 to 100 μg/ml) was accompanied by accordion-like contraction and amplification of the SCCmec element. Although slower growing than strain USA300, HoR34 outcompeted the parent strain in the presence of subinhibitory oxacillin. These data identify tandem amplification of the SCCmec element as a new mechanism of high-level methicillin resistance in MRSA, which may provide a competitive advantage for MRSA under antibiotic selection.
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Bacterial Signaling Nucleotides Inhibit Yeast Cell Growth by Impacting Mitochondrial and Other Specifically Eukaryotic Functions. mBio 2017; 8:mBio.01047-17. [PMID: 28743817 PMCID: PMC5527313 DOI: 10.1128/mbio.01047-17] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
We have engineered Saccharomyces cerevisiae to inducibly synthesize the prokaryotic signaling nucleotides cyclic di-GMP (cdiGMP), cdiAMP, and ppGpp in order to characterize the range of effects these nucleotides exert on eukaryotic cell function during bacterial pathogenesis. Synthetic genetic array (SGA) and transcriptome analyses indicated that, while these compounds elicit some common reactions in yeast, there are also complex and distinctive responses to each of the three nucleotides. All three are capable of inhibiting eukaryotic cell growth, with the guanine nucleotides exhibiting stronger effects than cdiAMP. Mutations compromising mitochondrial function and chromatin remodeling show negative epistatic interactions with all three nucleotides. In contrast, certain mutations that cause defects in chromatin modification and ribosomal protein function show positive epistasis, alleviating growth inhibition by at least two of the three nucleotides. Uniquely, cdiGMP is lethal both to cells growing by respiration on acetate and to obligately fermentative petite mutants. cdiGMP is also synthetically lethal with the ribonucleotide reductase (RNR) inhibitor hydroxyurea. Heterologous expression of the human ppGpp hydrolase Mesh1p prevented the accumulation of ppGpp in the engineered yeast and restored cell growth. Extensive in vivo interactions between bacterial signaling molecules and eukaryotic gene function occur, resulting in outcomes ranging from growth inhibition to death. cdiGMP functions through a mechanism that must be compensated by unhindered RNR activity or by functionally competent mitochondria. Mesh1p may be required for abrogating the damaging effects of ppGpp in human cells subjected to bacterial infection.IMPORTANCE During infections, pathogenic bacteria can release nucleotides into the cells of their eukaryotic hosts. These nucleotides are recognized as signals that contribute to the initiation of defensive immune responses that help the infected cells recover. Despite the importance of this process, the broader impact of bacterial nucleotides on the functioning of eukaryotic cells remains poorly defined. To address this, we genetically modified cells of the eukaryote Saccharomyces cerevisiae (baker's yeast) to produce three of these molecules (cdiAMP, cdiGMP, and ppGpp) and used the engineered strains as model systems to characterize the effects of the molecules on the cells. In addition to demonstrating that the nucleotides are each capable of adversely affecting yeast cell function and growth, we also identified the cellular functions important for mitigating the damage caused, suggesting possible modes of action. This study expands our understanding of the molecular interactions that can take place between bacterial and eukaryotic cells.
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Durhan E, Korcan SE, Altindis M, Konuk M. Fitness and competitive growth comparison of methicillin resistant and methicillin susceptible Staphylococcus aureus colonies. Microb Pathog 2017; 106:69-75. [DOI: 10.1016/j.micpath.2016.06.009] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2016] [Accepted: 06/06/2016] [Indexed: 10/21/2022]
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Abstract
Cyclic dinucleotides (CDNs) are highly versatile signalling molecules that control various important biological processes in bacteria. The best-studied example is cyclic di-GMP (c-di-GMP). Known since the late 1980s, it is now recognized as a near-ubiquitous second messenger that coordinates diverse aspects of bacterial growth and behaviour, including motility, virulence, biofilm formation and cell cycle progression. In this Review, we discuss important new insights that have been gained into the molecular principles of c-di-GMP synthesis and degradation, which are mediated by diguanylate cyclases and c-di-GMP-specific phosphodiesterases, respectively, and the cellular functions that are exerted by c-di-GMP-binding effectors and their diverse targets. Finally, we provide a short overview of the signalling versatility of other CDNs, including c-di-AMP and cGMP-AMP (cGAMP).
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Bowman L, Zeden MS, Schuster CF, Kaever V, Gründling A. New Insights into the Cyclic Di-adenosine Monophosphate (c-di-AMP) Degradation Pathway and the Requirement of the Cyclic Dinucleotide for Acid Stress Resistance in Staphylococcus aureus. J Biol Chem 2016; 291:26970-26986. [PMID: 27834680 PMCID: PMC5207132 DOI: 10.1074/jbc.m116.747709] [Citation(s) in RCA: 72] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2016] [Revised: 11/09/2016] [Indexed: 12/02/2022] Open
Abstract
Nucleotide signaling networks are key to facilitate alterations in gene expression, protein function, and enzyme activity in response to diverse stimuli. Cyclic di-adenosine monophosphate (c-di-AMP) is an important secondary messenger molecule produced by the human pathogen Staphylococcus aureus and is involved in regulating a number of physiological processes including potassium transport. S. aureus must ensure tight control over its cellular levels as both high levels of the dinucleotide and its absence result in a number of detrimental phenotypes. Here we show that in addition to the membrane-bound Asp-His-His and Asp-His-His-associated (DHH/DHHA1) domain-containing phosphodiesterase (PDE) GdpP, S. aureus produces a second cytoplasmic DHH/DHHA1 PDE Pde2. Although capable of hydrolyzing c-di-AMP, Pde2 preferentially converts linear 5'-phosphadenylyl-adenosine (pApA) to AMP. Using a pde2 mutant strain, pApA was detected for the first time in S. aureus, leading us to speculate that this dinucleotide may have a regulatory role under certain conditions. Moreover, pApA is involved in a feedback inhibition loop that limits GdpP-dependent c-di-AMP hydrolysis. Another protein linked to the regulation of c-di-AMP levels in bacteria is the predicted regulator protein YbbR. Here, it is shown that a ybbR mutant S. aureus strain has increased acid sensitivity that can be bypassed by the acquisition of mutations in a number of genes, including the gene coding for the diadenylate cyclase DacA. We further show that c-di-AMP levels are slightly elevated in the ybbR suppressor strains tested as compared with the wild-type strain. With this, we not only identified a new role for YbbR in acid stress resistance in S. aureus but also provide further insight into how c-di-AMP levels impact acid tolerance in this organism.
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Affiliation(s)
- Lisa Bowman
- From the Section of Microbiology and Medical Research Council Centre for Molecular Bacteriology and Infection, Imperial College London, London SW7 2AZ, United Kingdom and
| | - Merve S Zeden
- From the Section of Microbiology and Medical Research Council Centre for Molecular Bacteriology and Infection, Imperial College London, London SW7 2AZ, United Kingdom and
| | - Christopher F Schuster
- From the Section of Microbiology and Medical Research Council Centre for Molecular Bacteriology and Infection, Imperial College London, London SW7 2AZ, United Kingdom and
| | - Volkhard Kaever
- the Research Core Unit Metabolomics, Hannover Medical School, Hannover D-306625, Germany
| | - Angelika Gründling
- From the Section of Microbiology and Medical Research Council Centre for Molecular Bacteriology and Infection, Imperial College London, London SW7 2AZ, United Kingdom and
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Cyclic di-AMP Released from Staphylococcus aureus Biofilm Induces a Macrophage Type I Interferon Response. Infect Immun 2016; 84:3564-3574. [PMID: 27736778 PMCID: PMC5116733 DOI: 10.1128/iai.00447-16] [Citation(s) in RCA: 51] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2016] [Accepted: 10/01/2016] [Indexed: 12/14/2022] Open
Abstract
Staphylococcus aureus is a leading cause of community- and nosocomial-acquired infections, with a propensity for biofilm formation. S. aureus biofilms actively skew the host immune response toward an anti-inflammatory state; however, the biofilm effector molecules and the mechanism(s) of action responsible for this phenomenon remain to be fully defined. The essential bacterial second messenger cyclic diadenylate monophosphate (c-di-AMP) is an emerging pathogen-associated molecular pattern during intracellular bacterial infections, as c-di-AMP secretion into the infected host cytosol induces a robust type I interferon (IFN) response. Type I IFNs have the potential to exacerbate infectious outcomes by promoting anti-inflammatory effects; however, the type I IFN response to S. aureus biofilms is unknown. Additionally, while several intracellular proteins function as c-di-AMP receptors in S. aureus, it has yet to be determined if any extracellular role for c-di-AMP exists and its release during biofilm formation has not yet been demonstrated. This study examined the possibility that c-di-AMP released during S. aureus biofilm growth polarizes macrophages toward an anti-inflammatory phenotype via type I interferon signaling. DacA, the enzyme responsible for c-di-AMP synthesis in S. aureus, was highly expressed during biofilm growth, and 30 to 50% of total c-di-AMP produced from S. aureus biofilm was released extracellularly due to autolytic activity. S. aureus biofilm c-di-AMP release induced macrophage type I IFN expression via a STING-dependent pathway and promoted S. aureus intracellular survival in macrophages. These findings identify c-di-AMP as another mechanism for how S. aureus biofilms promote macrophage anti-inflammatory activity, which likely contributes to biofilm persistence.
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Pham TH, Liang ZX, Marcellin E, Turner MS. Replenishing the cyclic-di-AMP pool: regulation of diadenylate cyclase activity in bacteria. Curr Genet 2016; 62:731-738. [PMID: 27074767 DOI: 10.1007/s00294-016-0600-8] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2016] [Revised: 03/29/2016] [Accepted: 04/01/2016] [Indexed: 02/08/2023]
Abstract
Bacteria can sense environmental cues and alter their physiology accordingly through the use of signal transduction pathways involving second messenger nucleotides. One broadly conserved second messenger is cyclic-di-AMP (c-di-AMP) which regulates a range of processes including cell wall homeostasis, potassium uptake, DNA repair, fatty acid synthesis, biofilm formation and central metabolism in bacteria. The intracellular pool of c-di-AMP is maintained by the activities of diadenylate cyclase (DAC) and phosphodiesterase (PDE) enzymes, as well as possibly via c-di-AMP export. Whilst extracellular stimuli regulating c-di-AMP levels in bacteria are poorly understood, recent work has identified effector proteins which directly interact and alter the activity of DACs. These include the membrane bound CdaR and the phosphoglucosamine mutase GlmM which both bind directly to the membrane bound CdaA DAC and the recombination protein RadA which binds directly to the DNA binding DisA DAC. The genes encoding these multiprotein complexes are co-localised in many bacteria providing further support for their functional connection. The roles of GlmM in peptidoglycan synthesis and RadA in Holliday junction intermediate processing suggest that c-di-AMP synthesis by DACs will be responsive to these cellular activities. In addition to these modulatory interactions, permanent dysregulation of DAC activity due to suppressor mutations can occur during selection to overcome growth defects, rapid cell lysis and osmosensitivity. DACs have also been investigated as targets for the development of new antibiotics and several small compound inhibitors have recently been identified. This review aims to provide an overview of how c-di-AMP synthesis by DACs can be regulated.
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Affiliation(s)
- Thi Huong Pham
- School of Agriculture and Food Sciences, University of Queensland, Brisbane, QLD, Australia
| | - Zhao-Xun Liang
- School of Biological Sciences, Nanyang Technological University, Singapore, Singapore
| | - Esteban Marcellin
- Australian Institute for Bioengineering and Nanotechnology, University of Queensland, Brisbane, QLD, Australia
| | - Mark S Turner
- School of Agriculture and Food Sciences, University of Queensland, Brisbane, QLD, Australia.
- Queensland Alliance for Agriculture and Food Innovation, University of Queensland, Brisbane, QLD, Australia.
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Schuster CF, Bellows LE, Tosi T, Campeotto I, Corrigan RM, Freemont P, Gründling A. The second messenger c-di-AMP inhibits the osmolyte uptake system OpuC in Staphylococcus aureus. Sci Signal 2016; 9:ra81. [PMID: 27531650 PMCID: PMC5248971 DOI: 10.1126/scisignal.aaf7279] [Citation(s) in RCA: 74] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Staphylococcus aureus is an important opportunistic human pathogen that is highly resistant to osmotic stresses. To survive an increase in osmolarity, bacteria immediately take up potassium ions and small organic compounds known as compatible solutes. The second messenger cyclic diadenosine monophosphate (c-di-AMP) reduces the ability of bacteria to withstand osmotic stress by binding to and inhibiting several proteins that promote potassium uptake. We identified OpuCA, the adenosine triphosphatase (ATPase) component of an uptake system for the compatible solute carnitine, as a c-di-AMP target protein in S aureus and found that the LAC*ΔgdpP strain of S aureus, which overproduces c-di-AMP, showed reduced carnitine uptake. The paired cystathionine-β-synthase (CBS) domains of OpuCA bound to c-di-AMP, and a crystal structure revealed a putative binding pocket for c-di-AMP in the cleft between the two CBS domains. Thus, c-di-AMP inhibits osmoprotection through multiple mechanisms.
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Affiliation(s)
- Christopher F. Schuster
- Section of Microbiology and MRC Centre for Molecular Bacteriology and Infection, Imperial College London, London SW7 2AZ, UK
| | - Lauren E. Bellows
- Section of Microbiology and MRC Centre for Molecular Bacteriology and Infection, Imperial College London, London SW7 2AZ, UK
| | - Tommaso Tosi
- Section of Microbiology and MRC Centre for Molecular Bacteriology and Infection, Imperial College London, London SW7 2AZ, UK
| | - Ivan Campeotto
- Section of Microbiology and MRC Centre for Molecular Bacteriology and Infection, Imperial College London, London SW7 2AZ, UK
| | - Rebecca M. Corrigan
- Section of Microbiology and MRC Centre for Molecular Bacteriology and Infection, Imperial College London, London SW7 2AZ, UK
| | - Paul Freemont
- Section of Structural Biology, Department of Medicine, Imperial College London, London SW7 2AZ, UK
| | - Angelika Gründling
- Section of Microbiology and MRC Centre for Molecular Bacteriology and Infection, Imperial College London, London SW7 2AZ, UK
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47
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Liu P, Xue H, Wu Z, Ma J, Zhao X. Effect ofblaregulators on the susceptible phenotype and phenotypic conversion for oxacillin-susceptiblemecA-positive staphylococcal isolates. J Antimicrob Chemother 2016; 71:2105-12. [DOI: 10.1093/jac/dkw123] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2015] [Accepted: 03/14/2016] [Indexed: 11/14/2022] Open
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Role of the Stringent Stress Response in the Antibiotic Resistance Phenotype of Methicillin-Resistant Staphylococcus aureus. Antimicrob Agents Chemother 2016; 60:2311-7. [PMID: 26833147 DOI: 10.1128/aac.02697-15] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2015] [Accepted: 01/25/2016] [Indexed: 01/03/2023] Open
Abstract
Resistance to beta-lactam antibiotics in methicillin-resistantStaphylococcus aureus(MRSA) requires the presence of an acquired genetic determinant,mecAormecC, which encode penicillin-binding protein PBP2A or PBP2A', respectively. Although all MRSA strains share a mechanism of resistance, the phenotypic expression of beta-lactam resistance shows considerable strain-to-strain variation. The stringent stress response, a stress response that results from nutrient limitation, was shown to play a key role in determining the resistance level of an MRSA strain. In the present study, we validated the impact of the stringent stress response on transcription and translation ofmecAin the MRSA clinical isolate strain N315, which also carries known regulatory genes (mecI/mecR1/mecR2andblaI/blaR1) formecAtranscription. We showed that the impact of the stringent stress response on the resistance level may be restricted to beta-lactam resistance based on a "foreign" determinant such asmecA, as opposed to resistance based on mutations in the nativeS. aureusdeterminantpbpB(encoding PBP2). Our observations demonstrate that high-level resistance mediated by the stringent stress response follows the current model of beta-lactam resistance in which the native PBP2 protein is also essential for expression of the resistance phenotype. We also show that theStaphylococcus sciuri pbpDgene (also calledmecAI), the putative evolutionary precursor ofmecA, confers oxacillin resistance in anS. aureusstrain, generating a heterogeneous phenotype that can be converted to high and homogenous resistance by induction of the stringent stress response in the bacteria.
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Peng X, Zhang Y, Bai G, Zhou X, Wu H. Cyclic di-AMP mediates biofilm formation. Mol Microbiol 2016; 99:945-59. [PMID: 26564551 PMCID: PMC5003771 DOI: 10.1111/mmi.13277] [Citation(s) in RCA: 104] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/11/2015] [Indexed: 12/27/2022]
Abstract
Cyclic di-AMP (c-di-AMP) is an emerging second messenger in bacteria. It has been shown to play important roles in bacterial fitness and virulence. However, transduction of c-di-AMP signaling in bacteria and the role of c-di-AMP in biofilm formation are not well understood. The level of c-di-AMP is modulated by activity of di-adenylyl cyclase that produces c-di-AMP and phosphodiesterase (PDE) that degrades c-di-AMP. In this study, we determined that increased c-di-AMP levels by deletion of the pdeA gene coding for a PDE promoted biofilm formation in Streptococcus mutans. Deletion of pdeA upregulated expression of gtfB, the gene coding for a major glucan producing enzyme. Inactivation of gtfB blocked the increased biofilm by the pdeA mutant. Two c-di-AMP binding proteins including CabPA (SMU_1562) and CabPB (SMU_1708) were identified. Interestingly, only CabPA deficiency inhibited both the increased biofilm formation and the upregulated expression of GtfB observed in the pdeA mutant. In addition, CabPA but not CabPB interacted with VicR, a known transcriptional factor that regulates expression of gtfB, suggesting that a signaling link between CabPA and GtfB through VicR. Increased biofilm by the pdeA deficiency also enhanced bacterial colonization of Drosophila in vivo. Taken together, our studies reveal a new role of c-di-AMP in mediating biofilm formation through a CabPA/VicR/GtfB signaling network in S. mutans.
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Affiliation(s)
- Xian Peng
- Department of Pediatric Dentistry, University of Alabama at Birmingham, School of Dentistry, Birmingham, AL, USA
- State Key Laboratory of Oral Diseases, Sichuan University, Chengdu, China
| | - Yang Zhang
- Center for Immunology and Microbial Disease, MC-151, Albany Medical College, 47 New Scotland Avenue, Albany, NY, USA
| | - Guangchun Bai
- Center for Immunology and Microbial Disease, MC-151, Albany Medical College, 47 New Scotland Avenue, Albany, NY, USA
| | - Xuedong Zhou
- State Key Laboratory of Oral Diseases, Sichuan University, Chengdu, China
| | - Hui Wu
- Department of Pediatric Dentistry, University of Alabama at Birmingham, School of Dentistry, Birmingham, AL, USA
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Zhu Y, Pham TH, Nhiep THN, Vu NMT, Marcellin E, Chakrabortti A, Wang Y, Waanders J, Lo R, Huston WM, Bansal N, Nielsen LK, Liang ZX, Turner MS. Cyclic-di-AMP synthesis by the diadenylate cyclase CdaA is modulated by the peptidoglycan biosynthesis enzyme GlmM in Lactococcus lactis. Mol Microbiol 2015; 99:1015-27. [PMID: 26585449 DOI: 10.1111/mmi.13281] [Citation(s) in RCA: 52] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/17/2015] [Indexed: 12/28/2022]
Abstract
The second messenger cyclic-di-adenosine monophosphate (c-di-AMP) plays important roles in growth, virulence, cell wall homeostasis, potassium transport and affects resistance to antibiotics, heat and osmotic stress. Most Firmicutes contain only one c-di-AMP synthesizing diadenylate cyclase (CdaA); however, little is known about signals and effectors controlling CdaA activity and c-di-AMP levels. In this study, a genetic screen was employed to identify components which affect the c-di-AMP level in Lactococcus. We characterized suppressor mutations that restored osmoresistance to spontaneous c-di-AMP phosphodiesterase gdpP mutants, which contain high c-di-AMP levels. Loss-of-function and gain-of-function mutations were identified in the cdaA and gdpP genes, respectively, which led to lower c-di-AMP levels. A mutation was also identified in the phosphoglucosamine mutase gene glmM, which is commonly located within the cdaA operon in bacteria. The glmM I154F mutation resulted in a lowering of the c-di-AMP level and a reduction in the key peptidoglycan precursor UDP-N-acetylglucosamine in L. lactis. C-di-AMP synthesis by CdaA was shown to be inhibited by GlmM(I154F) more than GlmM and GlmM(I154F) was found to bind more strongly to CdaA than GlmM. These findings identify GlmM as a c-di-AMP level modulating protein and provide a direct connection between c-di-AMP synthesis and peptidoglycan biosynthesis.
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Affiliation(s)
- Yan Zhu
- School of Agriculture and Food Sciences, University of Queensland, Brisbane, Queensland, Australia
| | - Thi Huong Pham
- School of Agriculture and Food Sciences, University of Queensland, Brisbane, Queensland, Australia.,University of Science and Technology, The University of Danang, Da Nang, Vietnam
| | - Thi Hanh Nguyen Nhiep
- School of Agriculture and Food Sciences, University of Queensland, Brisbane, Queensland, Australia
| | - Ngoc Minh Thu Vu
- School of Agriculture and Food Sciences, University of Queensland, Brisbane, Queensland, Australia
| | - Esteban Marcellin
- Australian Institute for Bioengineering and Nanotechnology, The University of Queensland, Brisbane, Queensland, Australia
| | - Alolika Chakrabortti
- School of Biological Sciences, Nanyang Technological University, Singapore, Singapore
| | - Yuanliang Wang
- College of Food Science and Technology, Hunan Agricultural University, Changsha, Hunan Province, China
| | - Jennifer Waanders
- School of Agriculture and Food Sciences, University of Queensland, Brisbane, Queensland, Australia
| | - Raquel Lo
- School of Agriculture and Food Sciences, University of Queensland, Brisbane, Queensland, Australia
| | - Wilhelmina M Huston
- School of Life Sciences, University of Technology Sydney, Sydney, New South Wales, Australia
| | - Nidhi Bansal
- School of Agriculture and Food Sciences, University of Queensland, Brisbane, Queensland, Australia
| | - Lars K Nielsen
- Australian Institute for Bioengineering and Nanotechnology, The University of Queensland, Brisbane, Queensland, Australia
| | - Zhao-Xun Liang
- School of Biological Sciences, Nanyang Technological University, Singapore, Singapore
| | - Mark S Turner
- School of Agriculture and Food Sciences, University of Queensland, Brisbane, Queensland, Australia.,Queensland Alliance for Agriculture and Food Innovation, University of Queensland, Brisbane, Queensland, Australia
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