1
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Hu J, Yao J, Lei C, Sun X. c-di-AMP accumulation impairs toxin expression of Bacillus anthracis by down-regulating potassium importers. Microbiol Spectr 2024; 12:e0378623. [PMID: 38899864 PMCID: PMC11302148 DOI: 10.1128/spectrum.03786-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2023] [Accepted: 04/20/2024] [Indexed: 06/21/2024] Open
Abstract
The Gram-positive bacterium Bacillus anthracis is the causative agent of anthrax and a bioterrorism threat worldwide. As a crucial second messenger in many bacterial species, cyclic di-AMP (c-di-AMP) modulates various key processes for bacterial homeostasis and pathogenesis. Overaccumulation of c-di-AMP alters cellular growth and reduces anthrax toxin expression as well as virulence in Bacillus anthracis by unresolved underlying mechanisms. In this report, we discovered that c-di-AMP binds to a series of receptors involved in potassium uptake in B. anthracis. By analyzing Kdp and Ktr mutants for osmotic stress, gene expression, and anthrax toxin expression, we also showed that c-di-AMP inhibits Kdp operon expression through binding to the KdpD and ydaO riboswitch; up-regulating intracellular potassium promotes anthrax toxin expression in c-di-AMP accumulated B. anthracis. Decreased anthrax toxin expression at high c-di-AMP occurs through the inhibition of potassium uptake. Understanding the molecular basis of how potassium uptake affects anthrax toxin has the potential to provide new insight into the control of B. anthracis.IMPORTANCEThe bacterial second messenger cyclic di-AMP (c-di-AMP) is a conserved global regulator of potassium homeostasis. How c-di-AMP regulates bacterial virulence is unknown. With this study, we provide a link between potassium uptake and anthrax toxin expression in Bacillus anthracis. c-di-AMP accumulation might inhibit anthrax toxin expression by suppressing potassium uptake.
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Affiliation(s)
- Jia Hu
- Wuhan Institute of Virology, Center for Biosafety Mega-Science, Chinese Academy of Sciences, Wuhan, Hubei, China
| | - Junmin Yao
- Wuhan Institute of Virology, Center for Biosafety Mega-Science, Chinese Academy of Sciences, Wuhan, Hubei, China
- University of Chinese Academy of Sciences, Beijing, China
| | - Chengfeng Lei
- Wuhan Institute of Virology, Center for Biosafety Mega-Science, Chinese Academy of Sciences, Wuhan, Hubei, China
| | - Xiulian Sun
- Wuhan Institute of Virology, Center for Biosafety Mega-Science, Chinese Academy of Sciences, Wuhan, Hubei, China
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2
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Tu Z, Stevenson DM, McCaslin D, Amador-Noguez D, Huynh TN. The role of Listeria monocytogenes PstA in β-lactam resistance requires the cytochrome bd oxidase activity. J Bacteriol 2024:e0013024. [PMID: 38995039 DOI: 10.1128/jb.00130-24] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2024] [Accepted: 06/13/2024] [Indexed: 07/13/2024] Open
Abstract
c-di-AMP is an essential second messenger that binds and regulates several proteins of different functions within bacterial cells. Among those, PstA is a structurally conserved c-di-AMP-binding protein, but its function is largely unknown. PstA is structurally similar to PII signal transduction proteins, although it specifically binds c-di-AMP rather than other PII ligands such as ATP and α-ketoglutarate. In Listeria monocytogenes, we found that PstA increases β-lactam susceptibility at normal and low c-di-AMP levels, but increases β-lactam resistance upon c-di-AMP accumulation. Examining a PstA mutant defective for c-di-AMP binding, we found the apo form of PstA to be toxic for β-lactam resistance, and the c-di-AMP-bound form to be beneficial. Intriguingly, a role for PstA in β-lactam resistance is only prominent in aerobic cultures, and largely diminished under hypoxic conditions, suggesting that PstA function is linked to aerobic metabolism. However, PstA does not control aerobic growth rate, and has a modest influence on the tricarboxylic acid cycle and membrane potential-an indicator of cellular respiration. The regulatory role of PstA in β-lactam resistance is unrelated to reactive oxygen species or oxidative stress. Interestingly, during aerobic growth, PstA function requires the cytochrome bd oxidase (CydAB), a component of the respiratory electron transport chain. The requirement for CydAB might be related to its function in maintaining a membrane potential, or redox stress response activities. Altogether, we propose a model in which apo-PstA diminishes β-lactam resistance by interacting with an effector protein, and this activity can be countered by c-di-AMP binding or a by-product of redox stress. IMPORTANCE PstA is a structurally conserved c-di-AMP-binding protein that is broadly present among Firmicutes bacteria. Furthermore, PstA binds c-di-AMP at high affinity and specificity, indicating an important role in the c-di-AMP signaling network. However, the molecular function of PstA remains elusive. Our findings reveal contrasting roles of PstA in β-lactam resistance depending on c-di-AMP-binding status. We also define physiological conditions for PstA function during aerobic growth. Future efforts can exploit these conditions to identify PstA interaction partners under β-lactam stress.
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Affiliation(s)
- Zepeng Tu
- Food Science Department, University of Wisconsin-Madison, Madison, Wisconsin, USA
| | - David M Stevenson
- Department of Bacteriology, University of Wisconsin-Madison, Madison, Wisconsin, USA
| | - Darrel McCaslin
- Biophysics Instrumentation Facility, University of Wisconsin-Madison, Madison, Wisconsin, USA
| | - Daniel Amador-Noguez
- Department of Bacteriology, University of Wisconsin-Madison, Madison, Wisconsin, USA
| | - TuAnh N Huynh
- Food Science Department, University of Wisconsin-Madison, Madison, Wisconsin, USA
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3
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Brissac T, Guyonnet C, Sadouni A, Hernández-Montoya A, Jacquemet E, Legendre R, Sismeiro O, Trieu-Cuot P, Lanotte P, Tazi A, Firon A. Coordinated regulation of osmotic imbalance by c-di-AMP shapes ß-lactam tolerance in Group B Streptococcus. MICROLIFE 2024; 5:uqae014. [PMID: 38993744 PMCID: PMC11238645 DOI: 10.1093/femsml/uqae014] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/06/2024] [Revised: 06/03/2024] [Accepted: 06/11/2024] [Indexed: 07/13/2024]
Abstract
Streptococcus agalactiae is among the few pathogens that have not developed resistance to ß-lactam antibiotics despite decades of clinical use. The molecular basis of this long-lasting susceptibility has not been investigated, and it is not known whether specific mechanisms constrain the emergence of resistance. In this study, we first report ß-lactam tolerance due to the inactivation of the c-di-AMP phosphodiesterase GdpP. Mechanistically, tolerance depends on antagonistic regulation by the repressor BusR, which is activated by c-di-AMP and negatively regulates ß-lactam susceptibility through the BusAB osmolyte transporter and the AmaP/Asp23/GlsB cell envelope stress complex. The BusR transcriptional response is synergistic with the simultaneous allosteric inhibition of potassium and osmolyte transporters by c-di-AMP, which individually contribute to low-level ß-lactam tolerance. Genome-wide transposon mutagenesis confirms the role of GdpP and highlights functional interactions between a lysozyme-like hydrolase, the KhpAB RNA chaperone and the protein S immunomodulator in the response of GBS to ß-lactam. Overall, we demonstrate that c-di-AMP acts as a turgor pressure rheostat, coordinating an integrated response at the transcriptional and post-translational levels to cell wall weakening caused by ß-lactam activity, and reveal additional mechanisms that could foster resistance.
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Affiliation(s)
- Terry Brissac
- Department of Microbiology, Biology of Gram-positive Pathogens, Institut Pasteur, Université Paris Cité, 75015, Paris, France
| | - Cécile Guyonnet
- Université Paris Cité, Institut Cochin, Institut National de la Santé et de la Recherche Médicale U1016, Centre National de la Recherche Scientifique UMR8104, Team Bacteria and Perinatality, 75015, Paris, France
- Department of Bacteriology, French National Reference Center for Streptococci, Assistance Publique-Hôpitaux de Paris Hôpitaux Universitaires Paris Centre, Hôpital Cochin, 75005, Paris, France
- Fédération Hospitalo-Universitaire Fighting Prematurity, 75005, Paris, France
| | - Aymane Sadouni
- Department of Microbiology, Biology of Gram-positive Pathogens, Institut Pasteur, Université Paris Cité, 75015, Paris, France
| | - Ariadna Hernández-Montoya
- Department of Microbiology, Biology of Gram-positive Pathogens, Institut Pasteur, Université Paris Cité, 75015, Paris, France
| | - Elise Jacquemet
- Institut Pasteur, Université Paris Cité, Bioinformatics and Biostatistics Hub, 75015 Paris, France
| | - Rachel Legendre
- Institut Pasteur, Université Paris Cité, Bioinformatics and Biostatistics Hub, 75015 Paris, France
| | - Odile Sismeiro
- Department of Microbiology, Biology of Gram-positive Pathogens, Institut Pasteur, Université Paris Cité, 75015, Paris, France
| | - Patrick Trieu-Cuot
- Department of Microbiology, Biology of Gram-positive Pathogens, Institut Pasteur, Université Paris Cité, 75015, Paris, France
| | - Philippe Lanotte
- Université de Tours, INRAE, UMR 1282 ISP, 3700, Tours, France
- CHRU de Tours, Service de Bactériologie-Virologie, 37044, Tours, France
| | - Asmaa Tazi
- Université Paris Cité, Institut Cochin, Institut National de la Santé et de la Recherche Médicale U1016, Centre National de la Recherche Scientifique UMR8104, Team Bacteria and Perinatality, 75015, Paris, France
- Department of Bacteriology, French National Reference Center for Streptococci, Assistance Publique-Hôpitaux de Paris Hôpitaux Universitaires Paris Centre, Hôpital Cochin, 75005, Paris, France
- Fédération Hospitalo-Universitaire Fighting Prematurity, 75005, Paris, France
| | - Arnaud Firon
- Department of Microbiology, Biology of Gram-positive Pathogens, Institut Pasteur, Université Paris Cité, 75015, Paris, France
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4
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Lai LY, Satishkumar N, Cardozo S, Hemmadi V, Marques LB, Huang L, Filipe SR, Pinho MG, Chambers HF, Chatterjee SS. Altered PBP4 and GdpP functions synergistically mediate MRSA-like high-level, broad-spectrum β-lactam resistance in Staphylococcus aureus. mBio 2024; 15:e0288923. [PMID: 38530033 PMCID: PMC11077961 DOI: 10.1128/mbio.02889-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2023] [Accepted: 03/04/2024] [Indexed: 03/27/2024] Open
Abstract
Infections caused by Staphylococcus aureus are a leading cause of mortality worldwide. S. aureus infections caused by methicillin-resistant Staphylococcus aureus (MRSA) are particularly difficult to treat due to their resistance to next-generation β-lactams (NGBs) such as methicillin, nafcillin, and oxacillin. Resistance to NGBs, which is alternatively known as broad-spectrum β-lactam resistance, is classically mediated by PBP2a, a penicillin-binding protein encoded by mecA (or mecC) in MRSA. Thus, presence of mec genes among S. aureus spp. serves as the predictor of resistance to NGBs and facilitates determination of the proper therapeutic strategy for a staphylococcal infection. Although far less appreciated, mecA-deficient S. aureus strains can also exhibit NGB resistance. These strains, which are collectively termed as methicillin-resistant lacking mec (MRLM), are currently being identified in increasing numbers among natural resistant isolates of S. aureus. The mechanism/s through which MRLMs produce resistance to NGBs remains unknown. In this study, we demonstrate that mutations that alter PBP4 and GdpP functions, which are often present among MRLMs, can synergistically mediate resistance to NGBs. Furthermore, our results unravel that this novel mechanism potentially enables MRLMs to produce resistance toward NGBs at levels comparable to those of MRSAs. Our study provides a fresh new perspective about alternative mechanisms of NGB resistance, challenging our current overall understanding of high-level, broad-spectrum β-lactam resistance in S. aureus. It thus suggests reconsideration of the current approach toward diagnosis and treatment of β-lactam-resistant S. aureus infections. IMPORTANCE In Staphylococcus aureus, high-level, broad-spectrum resistance to β-lactams such as methicillin, also referred to as methicillin resistance, is largely attributed to mecA. This study demonstrates that S. aureus strains that lack mecA but contain mutations that functionally alter PBP4 and GdpP can also mediate high-level, broad-spectrum resistance to β-lactams. Resistance brought about by the synergistic action of functionally altered PBP4 and GdpP was phenotypically comparable to that displayed by mecA, as seen by increased bacterial survival in the presence of β-lactams. An analysis of mutations detected in naturally isolated strains of S. aureus revealed that a significant proportion of them had similar pbp4 and GGDEF domain protein containing phosphodiesterase (gdpP) mutations, making this study clinically significant. This study not only identifies important players of non-classical mechanisms of β-lactam resistance but also indicates reconsideration of current clinical diagnosis and treatment protocols of S. aureus infections.
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Affiliation(s)
- Li-Yin Lai
- Department of Microbial Pathogenesis, School of Dentistry, University of Maryland Baltimore, Baltimore, Maryland, USA
- Institute of Marine and Environmental Technology (IMET), Baltimore, Maryland, USA
| | - Nidhi Satishkumar
- Department of Microbial Pathogenesis, School of Dentistry, University of Maryland Baltimore, Baltimore, Maryland, USA
- Institute of Marine and Environmental Technology (IMET), Baltimore, Maryland, USA
| | - Sasha Cardozo
- Department of Microbial Pathogenesis, School of Dentistry, University of Maryland Baltimore, Baltimore, Maryland, USA
- Institute of Marine and Environmental Technology (IMET), Baltimore, Maryland, USA
| | - Vijay Hemmadi
- Department of Microbial Pathogenesis, School of Dentistry, University of Maryland Baltimore, Baltimore, Maryland, USA
- Institute of Marine and Environmental Technology (IMET), Baltimore, Maryland, USA
| | - Leonor B. Marques
- Instituto de Tecnologia Química e Biológica António Xavier, Universidade Nova de Lisboa, Oeiras, Portugal
| | - Liusheng Huang
- Department of Clinical Pharmacy, Drug Research Unit, University of California, San Francisco, California, USA
| | - Sergio R. Filipe
- Instituto de Tecnologia Química e Biológica António Xavier, Universidade Nova de Lisboa, Oeiras, Portugal
- UCIBIO-REQUIMTE, Departamento de Ciências da Vida, Faculdade de Ciências e Tecnologia, Universidade Nova de Lisboa, Caparica, Portugal
| | - Mariana G. Pinho
- Instituto de Tecnologia Química e Biológica António Xavier, Universidade Nova de Lisboa, Oeiras, Portugal
| | - Henry F. Chambers
- Division of Infectious Diseases, School of Medicine, University of California San Francisco, San Francisco, California, USA
| | - Som S. Chatterjee
- Department of Microbial Pathogenesis, School of Dentistry, University of Maryland Baltimore, Baltimore, Maryland, USA
- Institute of Marine and Environmental Technology (IMET), Baltimore, Maryland, USA
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Siletti C, Freeman M, Tu Z, Stevenson DM, Amador-Noguez D, Sauer JD, Huynh TN. C-di-AMP accumulation disrupts glutathione metabolism and inhibits virulence program expression in Listeria monocytogenes. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.01.18.576247. [PMID: 38293011 PMCID: PMC10827153 DOI: 10.1101/2024.01.18.576247] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/01/2024]
Abstract
C-di-AMP is an essential second messenger in many bacteria but its levels must be regulated. Unregulated c-di-AMP accumulation attenuates the virulence of many bacterial pathogens, including those that do not require c-di-AMP for growth. However, the mechanisms by which c-di-AMP regulates bacterial pathogenesis remain poorly understood. In Listeria monocytogenes , a mutant lacking both c-di-AMP phosphodiesterases, denoted as the ΔPDE mutant, accumulates a high c-di-AMP level and is significantly attenuated in the mouse model of systemic infection. All key L. monocytogenes virulence genes are transcriptionally upregulated by the master transcription factor PrfA, which is activated by reduced glutathione (GSH) during infection. Our transcriptomic analysis revealed that the ΔPDE mutant is significantly impaired for the expression of virulence genes within the PrfA core regulon. Subsequent quantitative gene expression analyses validated this phenotype both at the basal level and upon PrfA activation by GSH. A constitutively active PrfA * variant, PrfA G145S, which mimics the GSH-bound conformation, restores virulence gene expression in ΔPDE but only partially rescues virulence defect. Through GSH quantification and uptake assays, we found that the ΔPDE strain is significantly depleted for GSH, and that c-di-AMP inhibits GSH uptake. Constitutive expression of gshF (encoding a GSH synthetase) does not restore GSH levels in the ΔPDE strain, suggesting that c-di-AMP inhibits GSH synthesis activity or promotes GSH catabolism. Taken together, our data reveals GSH metabolism as another pathway that is regulated by c-di-AMP. C-di-AMP accumulation depletes cytoplasmic GSH levels within L. monocytogenes that leads to impaired virulence program expression. IMPORTANCE C-di-AMP regulates both bacterial pathogenesis and interactions with the host. Although c-di-AMP is essential in many bacteria, its accumulation also attenuates the virulence of many bacterial pathogens. Therefore, disrupting c-di-AMP homeostasis is a promising antibacterial treatment strategy, and has inspired several studies that screened for chemical inhibitors of c-di-AMP phosphodiesterases. However, the mechanisms by which c-di-AMP accumulation diminishes bacterial pathogenesis are poorly understood. Such understanding will reveal the molecular function of c-di-AMP, and inform therapeutic development strategies. Here, we identify GSH metabolism as a pathway regulated by c-di-AMP that is pertinent to L. monocytogenes replication in the host. Given the role of GSH as a virulence signal, nutrient, and antioxidant, GSH depletion impairs virulence program expression and likely diminishes host adaptation.
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6
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Wright MJ, Bai G. Bacterial second messenger cyclic di-AMP in streptococci. Mol Microbiol 2023; 120:791-804. [PMID: 37898560 DOI: 10.1111/mmi.15187] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2023] [Revised: 10/10/2023] [Accepted: 10/15/2023] [Indexed: 10/30/2023]
Abstract
Cyclic dimeric adenosine monophosphate (c-di-AMP) has been well studied in bacteria, including those of the genus Streptococcus, since the first recognition of this dinucleotide in 2008. Streptococci possess a sole diadenylate cyclase, CdaA, and distinct c-di-AMP phosphodiesterases. Interestingly, cdaA is required for viability of some streptococcal species but not all when streptococci are grown in standard laboratory media. Bacteria of this genus also have distinct c-di-AMP effector proteins, diverse c-di-AMP-signaling pathways, and subsequent biological outcomes. In streptococci, c-di-AMP may influence bacterial growth, morphology, biofilm formation, competence program, drug resistance, and bacterial pathogenesis. c-di-AMP secreted by streptococci has also been shown to interact with the mammalian host and induces immune responses including type I interferon production. In this review, we summarize the reported c-di-AMP networks in seven species of the genus Streptococcus, which cause diverse clinical manifestations, and propose future perspectives to investigate the signaling molecule in these streptococcal pathogens.
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Affiliation(s)
- Michael J Wright
- Department of Internal Medicine, Dartmouth Hitchcock Medical Center, Lebanon, New Hampshire, USA
| | - Guangchun Bai
- Department of Immunology and Microbial Disease, Albany Medical College, Albany, New York, USA
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7
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Lai LY, Satishkumar N, Cardozo S, Hemmadi V, Marques LB, Huang L, Filipe SR, Pinho MG, Chambers HF, Chatterjee SS. Altered PBP4 and GdpP functions synergistically mediate MRSA-like high-level, broad-spectrum β-lactam resistance in Staphylococcus aureus. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.10.26.564222. [PMID: 37961375 PMCID: PMC10634853 DOI: 10.1101/2023.10.26.564222] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/15/2023]
Abstract
Infections caused by Staphylococcus aureus are a leading cause of mortality worldwide. S. aureus infections caused by Methicillin-Resistant Staphylococcus aureus (MRSA) are particularly difficult to treat due to their resistance to Next Generation β-lactams (NGB) such as Methicillin, Nafcillin, Oxacillin etc. Resistance to NGBs, which is alternatively known as broad-spectrum β-lactam resistance is classically mediated by PBP2a, a Penicillin-Binding Protein encoded by mecA (or mecC) in MRSA. Thus, presence of mec genes among S. aureus serves as the predictor of resistance to NGBs and facilitates determination of the proper therapeutic strategy for a staphylococcal infection. Although far less appreciated, mecA deficient S. aureus strains can also exhibit NGB resistance. These strains, which are collectively termed as Methicillin-Resistant Lacking mec (MRLM) are currently being identified in increasing numbers among natural resistant isolates of S. aureus. The mechanism/s through which MRLMs produce resistance to NGBs remains unknown. In this study, we demonstrate that mutations that alter PBP4 and GdpP functions, which are often present among MRLMs can synergistically mediate resistance to NGBs. Furthermore, our results unravel that this novel mechanism potentially enables MRLMs to produce resistance towards NGBs at levels comparable to that of MRSAs. Our study, provides a fresh new perspective about alternative mechanisms of NGBs resistance, challenging our current overall understanding of high-level, broad-spectrum β-lactam resistance in S. aureus. It thus suggests reconsideration of the current approach towards diagnosis and treatment of β-lactam resistant S. aureus infections.
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Affiliation(s)
- Li-Yin Lai
- Department of Microbial Pathogenesis, School of Dentistry, University of Maryland Baltimore, USA
- Institute of Marine and Environmental Technology (IMET), Baltimore, USA
| | - Nidhi Satishkumar
- Department of Microbial Pathogenesis, School of Dentistry, University of Maryland Baltimore, USA
- Institute of Marine and Environmental Technology (IMET), Baltimore, USA
| | - Sasha Cardozo
- Department of Microbial Pathogenesis, School of Dentistry, University of Maryland Baltimore, USA
- Institute of Marine and Environmental Technology (IMET), Baltimore, USA
| | - Vijay Hemmadi
- Department of Microbial Pathogenesis, School of Dentistry, University of Maryland Baltimore, USA
- Institute of Marine and Environmental Technology (IMET), Baltimore, USA
| | - Leonor B. Marques
- Instituto de Tecnologia Química e Biológica António Xavier, Universidade Nova de Lisboa, Oeiras, Portugal
| | - Liusheng Huang
- Drug Research Unit, Department of Clinical Pharmacy, University of California, San Francisco, San Francisco, CA, USA
| | - Sergio R. Filipe
- Instituto de Tecnologia Química e Biológica António Xavier, Universidade Nova de Lisboa, Oeiras, Portugal
- UCIBIO-REQUIMTE, Departamento de Ciências da Vida, Faculdade de Ciências e Tecnologia, Universidade Nova de Lisboa, Caparica, Portugal
| | - Mariana G. Pinho
- Instituto de Tecnologia Química e Biológica António Xavier, Universidade Nova de Lisboa, Oeiras, Portugal
| | - Henry F. Chambers
- Division of Infectious Diseases, School of Medicine, University of California San Francisco, San Francisco, CA, USA
| | - Som S. Chatterjee
- Department of Microbial Pathogenesis, School of Dentistry, University of Maryland Baltimore, USA
- Institute of Marine and Environmental Technology (IMET), Baltimore, USA
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Chaudhary V, Pal AK, Singla M, Ghosh A. Elucidating the role of c-di-AMP in Mycobacterium smegmatis: Phenotypic characterization and functional analysis. Heliyon 2023; 9:e15686. [PMID: 37305508 PMCID: PMC10256829 DOI: 10.1016/j.heliyon.2023.e15686] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2022] [Revised: 04/17/2023] [Accepted: 04/18/2023] [Indexed: 06/13/2023] Open
Abstract
Cyclic-di-AMP (c-di-AMP) is an important secondary messenger molecule that plays a critical role in monitoring several important cellular processes, especially in several Gram-positive bacteria. In this study, we seek to unravel the physiological significance of the molecule c-di-AMP in Mycobacterium smegmatis under different conditions, using strains with altered c-di-AMP levels: c-di-AMP null mutant (ΔdisA) and a c-di-AMP over-expression mutant (Δpde). Our thorough analysis of the mutants revealed that the intracellular concentration of c-di-AMP could determine many basic phenotypes such as colony architecture, cell shape, cell size, membrane permeability etc. Additionally, it was shown to play a significant role in multiple stress adaptation pathways in the case of different DNA and membrane stresses. Our study also revealed how the biofilm phenotypes of M. smegmatis cells are altered with high intracellular c-di-AMP concentration. Next, we checked how c-di-AMP contributes to antibiotic resistance or susceptibility characteristics of M. smegmatis, which was followed by a detailed transcriptome profile analysis to reveal key genes and pathways such as translation, arginine biosynthesis, cell wall and plasma membrane are regulated by c-di-AMP in mycobacteria.
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9
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Oberkampf M, Hamiot A, Altamirano-Silva P, Bellés-Sancho P, Tremblay YDN, DiBenedetto N, Seifert R, Soutourina O, Bry L, Dupuy B, Peltier J. c-di-AMP signaling is required for bile salt resistance, osmotolerance, and long-term host colonization by Clostridioides difficile. Sci Signal 2022; 15:eabn8171. [PMID: 36067333 PMCID: PMC9831359 DOI: 10.1126/scisignal.abn8171] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
To colonize the host and cause disease, the human enteropathogen Clostridioides difficile must sense, respond, and adapt to the harsh environment of the gastrointestinal tract. We showed that the production and degradation of cyclic diadenosine monophosphate (c-di-AMP) were necessary during different phases of C. difficile growth, environmental adaptation, and infection. The production of this nucleotide second messenger was essential for growth because it controlled the uptake of potassium and also contributed to biofilm formation and cell wall homeostasis, whereas its degradation was required for osmotolerance and resistance to detergents and bile salts. The c-di-AMP binding transcription factor BusR repressed the expression of genes encoding the compatible solute transporter BusAA-AB. Compared with the parental strain, a mutant lacking BusR was more resistant to hyperosmotic and bile salt stresses, whereas a mutant lacking BusAA was more susceptible. A short exposure of C. difficile cells to bile salts decreased intracellular c-di-AMP concentrations, suggesting that changes in membrane properties induce alterations in the intracellular c-di-AMP concentration. A C. difficile strain that could not degrade c-di-AMP failed to persist in a mouse gut colonization model as long as the wild-type strain did. Thus, the production and degradation of c-di-AMP in C. difficile have pleiotropic effects, including the control of osmolyte uptake to confer osmotolerance and bile salt resistance, and its degradation is important for host colonization.
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Affiliation(s)
- Marine Oberkampf
- Institut Pasteur, Université Paris Cité, UMR-CNRS 6047, Laboratoire Pathogenèse des Bactéries Anaérobies, F-75015 Paris, France
| | - Audrey Hamiot
- Institut Pasteur, Université Paris Cité, UMR-CNRS 6047, Laboratoire Pathogenèse des Bactéries Anaérobies, F-75015 Paris, France
| | - Pamela Altamirano-Silva
- Centro de Investigación en Enfermedades Tropicales, Facultad de Microbiología, Universidad de Costa Rica, San José, Costa Rica
| | - Paula Bellés-Sancho
- Institut Pasteur, Université Paris Cité, UMR-CNRS 6047, Laboratoire Pathogenèse des Bactéries Anaérobies, F-75015 Paris, France
| | - Yannick D. N. Tremblay
- Institut Pasteur, Université Paris Cité, UMR-CNRS 6047, Laboratoire Pathogenèse des Bactéries Anaérobies, F-75015 Paris, France
| | - Nicholas DiBenedetto
- Massachusetts Host-Microbiome Center, Department of Pathology, Brigham and Women’s Hospital, Harvard Medical School, Boston, MA, USA
| | - Roland Seifert
- Institute of Pharmacology and Research Core Unit Metabolomics, Hannover Medical School, Hannover, Germany
| | - Olga Soutourina
- Université Paris-Saclay, CEA, CNRS, Institute for Integrative Biology of the Cell (I2BC), 91198 Gif-sur-Yvette, France
| | - Lynn Bry
- Massachusetts Host-Microbiome Center, Department of Pathology, Brigham and Women’s Hospital, Harvard Medical School, Boston, MA, USA
- Clinical Microbiology Laboratory, Department of Pathology, Brigham and Women’s Hospital, Boston, MA, USA
| | - Bruno Dupuy
- Institut Pasteur, Université Paris Cité, UMR-CNRS 6047, Laboratoire Pathogenèse des Bactéries Anaérobies, F-75015 Paris, France
| | - Johann Peltier
- Institut Pasteur, Université Paris Cité, UMR-CNRS 6047, Laboratoire Pathogenèse des Bactéries Anaérobies, F-75015 Paris, France
- Université Paris-Saclay, CEA, CNRS, Institute for Integrative Biology of the Cell (I2BC), 91198 Gif-sur-Yvette, France
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10
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Wang M, Wamp S, Gibhardt J, Holland G, Schwedt I, Schmidtke KU, Scheibner K, Halbedel S, Commichau FM. Adaptation of Listeria monocytogenes to perturbation of c-di-AMP metabolism underpins its role in osmoadaptation and identifies a fosfomycin uptake system. Environ Microbiol 2022; 24:4466-4488. [PMID: 35688634 DOI: 10.1111/1462-2920.16084] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2022] [Accepted: 05/25/2022] [Indexed: 11/29/2022]
Abstract
The human pathogen Listeria monocytogenes synthesizes and degrades c-di-AMP using the diadenylate cyclase CdaA and the phosphodiesterases PdeA and PgpH respectively. c-di-AMP is essential because it prevents the uncontrolled uptake of osmolytes. Here, we studied the phenotypes of cdaA, pdeA, pgpH and pdeA pgpH mutants with defects in c-di-AMP metabolism and characterized suppressor mutants restoring their growth defects. The characterization of the pdeA pgpH mutant revealed that the bacteria show growth defects in defined medium, a phenotype that is invariably suppressed by mutations in cdaA. The previously reported growth defect of the cdaA mutant in rich medium is suppressed by mutations that osmotically stabilize the c-di-AMP-free strain. We also found that the cdaA mutant has an increased sensitivity against isoleucine. The isoleucine-dependent growth inhibition of the cdaA mutant is suppressed by codY mutations that likely reduce the DNA-binding activity of encoded CodY variants. Moreover, the characterization of the cdaA suppressor mutants revealed that the Opp oligopeptide transport system is involved in the uptake of the antibiotic fosfomycin. In conclusion, the suppressor analysis corroborates a key function of c-di-AMP in controlling osmolyte homeostasis in L. monocytogenes.
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Affiliation(s)
- Mengyi Wang
- FG Synthetic Microbiology, Institute for Biotechnology, BTU Cottbus-Senftenberg, 01968, Senftenberg, Germany.,Department of General Microbiology, Institute for Microbiology and Genetics, University of Goettingen, 37077, Göttingen, Germany.,FG Molecular Microbiology, Institute of Biology, University of Hohenheim, 70599, Stuttgart, Germany
| | - Sabrina Wamp
- Division of Enteropathogenic Bacteria and Legionella, Robert-Koch-Institute, 38855, Wernigerode, Germany
| | - Johannes Gibhardt
- FG Synthetic Microbiology, Institute for Biotechnology, BTU Cottbus-Senftenberg, 01968, Senftenberg, Germany.,Department of General Microbiology, Institute for Microbiology and Genetics, University of Goettingen, 37077, Göttingen, Germany.,Research Complex NanoBio, Peter the Great Saint Petersburg Polytechnic University, Politekhnicheskaya ulitsa 29A, Saint Petersburg, 195251, Russia
| | - Gudrun Holland
- ZBS4 - Advanced Light and Electron Microscopy, Robert-Koch-Institute, Seestraße 10, 13353, Berlin, Germany
| | - Inge Schwedt
- FG Synthetic Microbiology, Institute for Biotechnology, BTU Cottbus-Senftenberg, 01968, Senftenberg, Germany.,FG Molecular Microbiology, Institute of Biology, University of Hohenheim, 70599, Stuttgart, Germany
| | - Kai-Uwe Schmidtke
- FG Enzyme Technology, Institute for Biotechnology, BTU Cottbus-Senftenberg, 01968, Senftenberg, Germany
| | - Katrin Scheibner
- FG Enzyme Technology, Institute for Biotechnology, BTU Cottbus-Senftenberg, 01968, Senftenberg, Germany
| | - Sven Halbedel
- Division of Enteropathogenic Bacteria and Legionella, Robert-Koch-Institute, 38855, Wernigerode, Germany
| | - Fabian M Commichau
- FG Synthetic Microbiology, Institute for Biotechnology, BTU Cottbus-Senftenberg, 01968, Senftenberg, Germany.,FG Molecular Microbiology, Institute of Biology, University of Hohenheim, 70599, Stuttgart, Germany
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11
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Zhang Y, Xu Z, Luo H, Hao X, Li M. 细菌c-di-AMP特异性磷酸二酯酶的研究进展. CHINESE SCIENCE BULLETIN-CHINESE 2022. [DOI: 10.1360/tb-2022-0064] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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12
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Mudgal S, Manikandan K, Mukherjee A, Krishnan A, Sinha KM. Cyclic di-AMP: Small molecule with big roles in bacteria. Microb Pathog 2021; 161:105264. [PMID: 34715302 DOI: 10.1016/j.micpath.2021.105264] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2021] [Revised: 08/20/2021] [Accepted: 10/21/2021] [Indexed: 01/15/2023]
Abstract
Cyclic dinucleotides are second messengers that are present in all the three domains of life, bacteria, archaea, and eukaryotes. These dinucleotides have important physiological and pathophysiological roles in bacteria. Cyclic di-AMP (cdA) is one of the recently discovered cyclic dinucleotides present predominantly in gram-positive bacteria. cdA is synthesized through diadenylate cyclase (DAC) activity from ATP in a two-step process and hydrolyzed to linear dinucleotide pApA (and to 5' AMP in certain cases) by specific phosphodiesterases. cdA regulates various physiological processes like K+ transport and osmotic balance, DNA repair, cell wall homeostasis, drug resistance, central metabolism either by binding directly to the target protein or regulating its expression. It also participates in host-pathogen interaction by binding to host immune receptors ERAdP, RECON, and STING.
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Affiliation(s)
- Sudhanshu Mudgal
- Amity Institute of Biotechnology, Amity University Haryana, Haryana, India
| | - Kasi Manikandan
- Amity Institute of Biotechnology, Amity University Haryana, Haryana, India
| | - Ahana Mukherjee
- Amity Institute of Biotechnology, Amity University Haryana, Haryana, India
| | - Anuja Krishnan
- Department of Molecular Medicine, Jamia Hamdard, New Delhi, India.
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13
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NrnA is a linear dinucleotide phosphodiesterase with limited function in cyclic dinucleotide metabolism in Listeria monocytogenes. J Bacteriol 2021; 204:e0020621. [PMID: 34662239 DOI: 10.1128/jb.00206-21] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Listeria monocytogenes produces both c-di-AMP and c-di-GMP to mediate many important cellular processes, but the levels of both nucleotides must be regulated. C-di-AMP accumulation attenuates virulence and diminishes stress response, and c-di-GMP accumulation impairs bacterial motility. An important regulatory mechanism to maintain c-di-AMP and c-di-GMP homeostasis is to hydrolyze them to the linear dinucleotides pApA and pGpG, respectively, but the fates of these hydrolytic products have not been examined in L. monocytogenes. We found that NrnA, a stand-alone DHH-DHHA1 phosphodiesterase, has a broad substrate range, but with a strong preference for linear dinucleotides over cyclic dinucleotides. Although NrnA exhibited detectable cyclic dinucleotide hydrolytic activities in vitro, NrnA had negligible effects on their levels in the bacterial cell, even in the absence of the c-di-AMP phosphodiesterases PdeA and PgpH. The ΔnrnA mutant had a mammalian cell infection defect that was fully restored by E. coli Orn. Together, our data indicate that L. monocytogenes NrnA is functionally orthologous to Orn, and its preferred physiological substrates are most likely linear dinucleotides. Furthermore, our findings revealed that, unlike some other c-di-AMP and c-di-GMP-producing bacteria, L. monocytogenes does not employ their hydrolytic products to regulate their phosphodiesterases, at least at the pApA and pGpG levels in the ΔnrnA mutant. Finally, the ΔnrnA infection defect was overcome by constitutive activation of PrfA, the master virulence regulator, suggesting that accumulated linear dinucleotides might inhibit the expression, stability, or function of PrfA-regulated virulence factors. IMPORTANCE Listeria monocytogenes produces both c-di-AMP and c-di-GMP, and encodes specific phosphodiesterases that degrade them into pApA and pGpG, respectively, but the metabolism of these products has not been characterized in this bacterium. We found that L. monocytogenes NrnA degrades a broad range of nucleotides. Among the tested cyclic and linear substrates, it exhibits a strong biochemical and physiological preference the linear dinucleotides pApA, pGpG, and pApG. Unlike in some other bacteria, these oligoribonucleotides do not appear to interfere with cyclic dinucleotide hydrolysis. The absence of NrnA is well tolerated by L. monocytogenes in broth cultures but impairs its ability to infect mammalian cells. These findings indicate a separation of cyclic dinucleotide signaling and oligoribonucleotide metabolism in L. monocytogenes.
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14
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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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15
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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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16
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A rationally designed c-di-AMP FRET biosensor to monitor nucleotide dynamics. J Bacteriol 2021; 203:e0008021. [PMID: 34309402 DOI: 10.1128/jb.00080-21] [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
3'3'-cyclic di-adenosine monophosphate (c-di-AMP) is an important nucleotide second messenger found throughout the bacterial domain of life. C-di-AMP is essential in many bacteria and regulates a diverse array of effector proteins controlling pathogenesis, cell wall homeostasis, osmoregulation, and central metabolism. Despite the ubiquity and importance of c-di-AMP, methods to detect this signaling molecule are limited, particularly at single cell resolution. In this work, crystallization of the Listeria monocytogenes c-di-AMP effector protein Lmo0553 enabled structure guided design of a Förster resonance energy transfer (FRET) based biosensor, which we have named CDA5. CDA5 is a fully genetically encodable, specific, and reversible biosensor which allows for the detection of c-di-AMP dynamics both in vitro and within live cells in a nondestructive manner. Our initial studies identify a distribution of c-di-AMP in Bacillus subtilis populations first grown in Luria Broth and then resuspended in diluted Luria Broth compatible with florescence analysis. Furthermore, we find that B. subtilis mutants lacking either a c-di-AMP phosphodiesterase or cyclase have respectively higher and lower FRET responses. These findings provide novel insight into the c-di-AMP distribution within bacterial populations and establish CDA5 as a powerful platform for characterizing new aspects of c-di-AMP regulation. Importance C-di-AMP is an important nucleotide second messenger for which detection methods are severely limited. In this work we engineer and implement a c-di-AMP specific FRET biosensor to remedy this dearth. We present this biosensor, CDA5, as a versatile tool to investigate previously intractable facets of c-di-AMP biology.
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17
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Cyclic di-AMP Oversight of Counter-Ion Osmolyte Pools Impacts Intrinsic Cefuroxime Resistance in Lactococcus lactis. mBio 2021; 12:mBio.00324-21. [PMID: 33832972 PMCID: PMC8092236 DOI: 10.1128/mbio.00324-21] [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] [Indexed: 11/21/2022] Open
Abstract
The bacterial second messenger cyclic di-AMP (c-di-AMP) is a global regulator of potassium homeostasis and compatible solute uptake in many Gram-positive bacteria, making it essential for osmoregulation. The role that c-di-AMP plays in β-lactam resistance, however, is unclear despite being first identified a decade ago. The broadly conserved cyclic di-AMP (c-di-AMP) is a conditionally essential bacterial second messenger. The pool of c-di-AMP is fine-tuned through diadenylate cyclase and phosphodiesterase activities, and direct binding of c-di-AMP to proteins and riboswitches allows the regulation of a broad spectrum of cellular processes. c-di-AMP has a significant impact on intrinsic β-lactam antibiotic resistance in Gram-positive bacteria; however, the reason for this is currently unclear. In this work, genetic studies revealed that suppressor mutations that decrease the activity of the potassium (K+) importer KupB or the glutamine importer GlnPQ restore cefuroxime (CEF) resistance in diadenylate cyclase (cdaA) mutants of Lactococcus lactis. Metabolite analyses showed that glutamine is imported by GlnPQ and then rapidly converted to glutamate, and GlnPQ mutations or c-di-AMP negatively affects the pools of the most abundant free amino acids (glutamate and aspartate) during growth. In a high-c-di-AMP mutant, GlnPQ activity could be increased by raising the internal K+ level through the overexpression of a c-di-AMP-insensitive KupB variant. These results demonstrate that c-di-AMP reduces GlnPQ activity and, therefore, the level of the major free anions in L. lactis through its inhibition of K+ import. Excessive ion accumulation in cdaA mutants results in greater spontaneous cell lysis under hypotonic conditions, while CEF-resistant suppressors exhibit reduced cell lysis and lower osmoresistance. This work demonstrates that the overaccumulation of major counter-ion osmolyte pools in c-di-AMP-defective mutants of L. lactis causes cefuroxime sensitivity.
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18
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Ducret A, Grangeasse C. Recent progress in our understanding of peptidoglycan assembly in Firmicutes. Curr Opin Microbiol 2021; 60:44-50. [PMID: 33588129 DOI: 10.1016/j.mib.2021.01.011] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2020] [Revised: 01/13/2021] [Accepted: 01/27/2021] [Indexed: 02/06/2023]
Abstract
Years of intense research have shown that the assembly of peptidoglycan, the extracellular mesh-like polymer surrounding the bacterial cell, is incredibly complex. It requires a suite of reactions catalyzed by dynamic macromolecular protein complexes whose localization and activity should be finely regulated in space and time. In this review, we focus on the main developments reported over the last five years for the assembly of peptidoglycan in Firmicutes, a bacterial phylum that comprises monoderm bacteria and that encompasses well studied bacterial models with different cell shapes and lifestyles.
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Affiliation(s)
- Adrien Ducret
- Molecular Microbiology and Structural Biochemistry, CNRS UMR 5086, Université de Lyon, 7 passage du Vercors, 69367 Lyon, France
| | - Christophe Grangeasse
- Molecular Microbiology and Structural Biochemistry, CNRS UMR 5086, Université de Lyon, 7 passage du Vercors, 69367 Lyon, France.
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Dutta A, Batish M, Parashar V. Structural basis of KdpD histidine kinase binding to the second messenger c-di-AMP. J Biol Chem 2021; 296:100771. [PMID: 33989637 PMCID: PMC8214093 DOI: 10.1016/j.jbc.2021.100771] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2021] [Revised: 05/03/2021] [Accepted: 05/07/2021] [Indexed: 11/17/2022] Open
Abstract
The KdpDE two-component system regulates potassium homeostasis and virulence in various bacterial species. The KdpD histidine kinases (HK) of this system contain a universal stress protein (USP) domain which binds to the second messenger cyclic-di-adenosine monophosphate (c-di-AMP) for regulating transcriptional output from this two-component system in Firmicutes such as Staphylococcus aureus. However, the structural basis of c-di-AMP specificity within the KdpD-USP domain is not well understood. Here, we resolved a 2.3 Å crystal structure of the S. aureus KdpD-USP domain (USPSa) complexed with c-di-AMP. Binding affinity analyses of USPSa mutants targeting the observed USPSa:c-di-AMP structural interface enabled the identification of the sequence residues that are required for c-di-AMP specificity. Based on the conservation of these residues in other Firmicutes, we identified the binding motif, (A/G/C)XSXSX2N(Y/F), which allowed us to predict c-di-AMP binding in other KdpD HKs. Furthermore, we found that the USPSa domain contains structural features distinct from the canonical standalone USPs that bind ATP as a preferred ligand. These features include inward-facing conformations of its β1-α1 and β4-α4 loops, a short α2 helix, the absence of a triphosphate-binding Walker A motif, and a unique dual phospho-ligand binding mode. It is therefore likely that USPSa-like domains in KdpD HKs represent a novel subfamily of the USPs.
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Affiliation(s)
- Anirudha Dutta
- Department of Medical and Molecular Sciences, University of Delaware, Newark, Delaware, USA
| | - Mona Batish
- Department of Medical and Molecular Sciences, University of Delaware, Newark, Delaware, USA
| | - Vijay Parashar
- Department of Medical and Molecular Sciences, University of Delaware, Newark, Delaware, USA.
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