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Hsu D, Flynn JR, Schuler CJ, Santelli CM, Toner BM, Bond DR, Gralnick JA. Isolation and genomic analysis of " Metallumcola ferriviriculae" MK1, a Gram-positive, Fe(III)-reducing bacterium from the Soudan Underground Mine, an iron-rich Martian analog site. Appl Environ Microbiol 2024; 90:e0004424. [PMID: 39007603 DOI: 10.1128/aem.00044-24] [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] [Received: 01/10/2024] [Accepted: 06/18/2024] [Indexed: 07/16/2024] Open
Abstract
The Soudan Underground Mine State Park, found in the Vermilion Iron Range in northern Minnesota, provides access to a ~ 2.7 billion-year-old banded iron formation. Exploratory boreholes drilled between 1958 and 1962 on the 27th level (713 m underground) of the mine intersect calcium and iron-rich brines that have recently been subject to metagenomic analysis and microbial enrichments. Using concentrated brine samples pumped from a borehole depth of up to 55 m, a novel Gram-positive bacterium was enriched under anaerobic, acetate-oxidizing, and Fe(III) citrate-reducing conditions. The isolated bacterium, designated strain MK1, is non-motile, rod-shaped, spore-forming, anaerobic, and mesophilic, with a growth range between 24°C and 30°C. The complete circular MK1 genome was found to be 3,720,236 bp and encodes 25 putative multiheme cytochromes, including homologs to inner membrane cytochromes in the Gram-negative bacterium Geobacter sulfurreducens and cytoplasmic membrane and periplasmic cytochromes in the Gram-positive bacterium Thermincola potens. However, MK1 does not encode homologs of the peptidoglycan (CwcA) and cell surface-associated (OcwA) multiheme cytochromes proposed to be required by T. potens to perform extracellular electron transfer. The 16S rRNA gene sequence of MK1 indicates that its closest related isolate is Desulfitibacter alkalitolerans strain sk.kt5 (91% sequence identity), which places MK1 in a novel genus within the Desulfitibacteraceae family and Moorellales order. Within the Moorellales order, only Calderihabitans maritimus strain KKC1 has been reported to reduce Fe(III), and only D. alkalitolerans can also grow in temperatures below 40°C. Thus, MK1 represents a novel species within a novel genus, for which we propose the name "Metallumcola ferriviriculae" strain MK1, and provides a unique opportunity to study a cytochrome-rich, mesophilic, Gram-positive, spore-forming Fe(III)-reducing bacterium.IMPORTANCEThe Soudan Underground Mine State Park gives access to understudied regions of the deep terrestrial subsurface that potentially predate the Great Oxidation Event. Studying organisms that have been relatively unperturbed by surface conditions for as long as 2.7 billion years may give us a window into ancient life before oxygen dominated the planet. Additionally, studying microbes from anoxic and iron-rich environments can help us better understand the requirements of life in analogous environments, such as on Mars. The isolation and characterization of "Metallumcola ferriviriculae" strain MK1 give us insights into a novel genus and species that is distinct both from its closest related isolates and from iron reducers characterized to date. "M. ferriviriculae" strain MK1 may also act as a model organism to study how the processes of sporulation and germination are affected by insoluble extracellular acceptors, as well as the impact of spores in the deep terrestrial biosphere.
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Affiliation(s)
- David Hsu
- BioTechnology Institute, University of Minnesota-Twin Cities, St. Paul, Minnesota, USA
- Department of Plant and Microbial Biology, University of Minnesota-Twin Cities, St. Paul, Minnesota, USA
| | - Jack R Flynn
- BioTechnology Institute, University of Minnesota-Twin Cities, St. Paul, Minnesota, USA
- Department of Plant and Microbial Biology, University of Minnesota-Twin Cities, St. Paul, Minnesota, USA
| | - Christopher J Schuler
- BioTechnology Institute, University of Minnesota-Twin Cities, St. Paul, Minnesota, USA
- Department of Earth and Environmental Sciences, University of Minnesota-Twin Cities, Minneapolis, Minnesota, USA
| | - Cara M Santelli
- BioTechnology Institute, University of Minnesota-Twin Cities, St. Paul, Minnesota, USA
- Department of Earth and Environmental Sciences, University of Minnesota-Twin Cities, Minneapolis, Minnesota, USA
| | - Brandy M Toner
- BioTechnology Institute, University of Minnesota-Twin Cities, St. Paul, Minnesota, USA
- Department of Earth and Environmental Sciences, University of Minnesota-Twin Cities, Minneapolis, Minnesota, USA
- Department of Soil, Water, and Climate, University of Minnesota-Twin Cities, St. Paul, Minnesota, USA
| | - Daniel R Bond
- BioTechnology Institute, University of Minnesota-Twin Cities, St. Paul, Minnesota, USA
- Department of Plant and Microbial Biology, University of Minnesota-Twin Cities, St. Paul, Minnesota, USA
| | - Jeffrey A Gralnick
- BioTechnology Institute, University of Minnesota-Twin Cities, St. Paul, Minnesota, USA
- Department of Plant and Microbial Biology, University of Minnesota-Twin Cities, St. Paul, Minnesota, USA
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2
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Furtado KL, Plott L, Markovetz M, Powers D, Wang H, Hill DB, Papin J, Allbritton NL, Tamayo R. Clostridioides difficile-mucus interactions encompass shifts in gene expression, metabolism, and biofilm formation. mSphere 2024; 9:e0008124. [PMID: 38837404 PMCID: PMC11332178 DOI: 10.1128/msphere.00081-24] [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] [Received: 02/01/2024] [Accepted: 04/28/2024] [Indexed: 06/07/2024] Open
Abstract
In a healthy colon, the stratified mucus layer serves as a crucial innate immune barrier to protect the epithelium from microbes. Mucins are complex glycoproteins that serve as a nutrient source for resident microflora and can be exploited by pathogens. We aimed to understand how the intestinal pathogen, Clostridioides difficile, independently uses or manipulates mucus to its benefit, without contributions from members of the microbiota. Using a 2-D primary human intestinal epithelial cell model to generate physiologic mucus, we assessed C. difficile-mucus interactions through growth assays, RNA-Seq, biophysical characterization of mucus, and contextualized metabolic modeling. We found that host-derived mucus promotes C. difficile growth both in vitro and in an infection model. RNA-Seq revealed significant upregulation of genes related to central metabolism in response to mucus, including genes involved in sugar uptake, the Wood-Ljungdahl pathway, and the glycine cleavage system. In addition, we identified differential expression of genes related to sensing and transcriptional control. Analysis of mutants with deletions in highly upregulated genes reflected the complexity of C. difficile-mucus interactions, with potential interplay between sensing and growth. Mucus also stimulated biofilm formation in vitro, which may in turn alter the viscoelastic properties of mucus. Context-specific metabolic modeling confirmed differential metabolism and the predicted importance of enzymes related to serine and glycine catabolism with mucus. Subsequent growth experiments supported these findings, indicating mucus is an important source of serine. Our results better define responses of C. difficile to human gastrointestinal mucus and highlight flexibility in metabolism that may influence pathogenesis. IMPORTANCE Clostridioides difficile results in upward of 250,000 infections and 12,000 deaths annually in the United States. Community-acquired infections continue to rise, and recurrent disease is common, emphasizing a vital need to understand C. difficile pathogenesis. C. difficile undoubtedly interacts with colonic mucus, but the extent to which the pathogen can independently respond to and take advantage of this niche has not been explored extensively. Moreover, the metabolic complexity of C. difficile remains poorly understood but likely impacts its capacity to grow and persist in the host. Here, we demonstrate that C. difficile uses native colonic mucus for growth, indicating C. difficile possesses mechanisms to exploit the mucosal niche. Furthermore, mucus induces metabolic shifts and biofilm formation in C. difficile, which has potential ramifications for intestinal colonization. Overall, our work is crucial to better understand the dynamics of C. difficile-mucus interactions in the context of the human gut.
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Affiliation(s)
- Kathleen L. Furtado
- Department of Microbiology and Immunology, University of North Carolina at Chapel Hill School of Medicine, Chapel Hill, North Carolina, USA
| | - Lucas Plott
- Marsico Lung Institute, University of North Carolina at Chapel Hill School of Medicine, Chapel Hill, North Carolina, USA
| | - Matthew Markovetz
- Marsico Lung Institute, University of North Carolina at Chapel Hill School of Medicine, Chapel Hill, North Carolina, USA
| | - Deborah Powers
- Department of Biochemistry and Molecular Genetics, University of Virginia, Charlottesville, Virginia, USA
| | - Hao Wang
- Department of Bioengineering, University of Washington, Seattle, Washington, USA
| | - David B. Hill
- Marsico Lung Institute, University of North Carolina at Chapel Hill School of Medicine, Chapel Hill, North Carolina, USA
- Joint Department of Biomedical Engineering, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA
- Department of Physics and Astronomy, College of Arts and Sciences, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA
| | - Jason Papin
- Department of Biochemistry and Molecular Genetics, University of Virginia, Charlottesville, Virginia, USA
- Department of Biomedical Engineering, University of Virginia, Charlottesville, Virginia, USA
- Department of Medicine, Division of Infectious Diseases and International Health, University of Virginia, Charlottesville, Virginia, USA
| | - Nancy L. Allbritton
- Department of Bioengineering, University of Washington, Seattle, Washington, USA
| | - Rita Tamayo
- Department of Microbiology and Immunology, University of North Carolina at Chapel Hill School of Medicine, Chapel Hill, North Carolina, USA
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3
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BELITSKY BORISR. Histidine kinase-mediated cross-regulation of the vancomycin-resistance operon in Clostridioides difficile. Mol Microbiol 2024; 121:1182-1199. [PMID: 38690761 PMCID: PMC11176017 DOI: 10.1111/mmi.15273] [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: 02/20/2024] [Revised: 04/03/2024] [Accepted: 04/17/2024] [Indexed: 05/03/2024]
Abstract
The dipeptide D-Ala-D-Ala is an essential component of peptidoglycan and the target of vancomycin. Most Clostridioides difficile strains possess the vanG operon responsible for the synthesis of D-Ala-D-Ser, which can replace D-Ala-D-Ala in peptidoglycan. The C. difficile vanG operon is regulated by a two-component system, VanRS, but is not induced sufficiently by vancomycin to confer resistance to this antibiotic. Surprisingly, in the absence of the VanS histidine kinase (HK), the vanG operon is still induced by vancomycin and also by another antibiotic, ramoplanin, in a VanR-dependent manner. This suggested the cross-regulation of VanR by another HK or kinases that are activated in the presence of certain lipid II-targeting antibiotics. We identified these HKs as CD35990 and CD22880. However, mutations in either or both HKs did not affect the regulation of the vanG operon in wild-type cells suggesting that intact VanS prevents the cross-activation of VanR by non-cognate HKs. Overproduction of VanR in the absence of VanS, CD35990, and CD22880 led to high expression of the vanG operon indicating that VanR can potentially utilize at least one more phosphate donor for its activation. Candidate targets of CD35990- and CD22880-mediated regulation in the presence of vancomycin or ramoplanin were identified by RNA-Seq.
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Affiliation(s)
- BORIS R. BELITSKY
- Department of Molecular Biology and Microbiology, Tufts University School of Medicine, Boston, Massachusetts 02111, USA
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4
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Warren Norris MAH, Plaskon DM, Tamayo R. Phase Variation of Flagella and Toxins in Clostridioides difficile is Mediated by Selective Rho-dependent Termination. J Mol Biol 2024; 436:168456. [PMID: 38278436 PMCID: PMC10942720 DOI: 10.1016/j.jmb.2024.168456] [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: 10/26/2023] [Revised: 01/16/2024] [Accepted: 01/20/2024] [Indexed: 01/28/2024]
Abstract
Clostridioides difficile is an intestinal pathogen that exhibits phase variation of flagella and toxins through inversion of the flagellar (flg) switch controlling flagellar and toxin gene expression. The transcription termination factor Rho preferentially inhibits swimming motility of bacteria with the 'flg-OFF' switch sequence. How C. difficile Rho mediates this selectivity was unknown. C. difficile Rho contains an N-terminal insertion domain (NID) which is found in a subset of Rho orthologues and confers diverse functions. Here we determined how Rho distinguishes between flg-ON and -OFF mRNAs and the roles of the NID and other domains of C. difficile Rho. Using in vitro ATPase assays, we determined that Rho specifically binds a region containing the left inverted repeat of the flg switch, but only of flg-OFF mRNA, indicating that differential termination is mediated by selective Rho binding. Using a suite of in vivo and in vitro assays in C. difficile, we determined that the NID is essential for Rho termination of flg-OFF mRNA, likely by influencing the ability to form stable hexamers, and the RNA binding domain is critical for flg-OFF specific termination. This work gives insight into the novel mechanism by which Rho interacts with flg mRNA to mediate phase variation of flagella and toxins in C. difficile and broadens our understanding of Rho-mediated termination in an organism with an AT-rich genome.
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Affiliation(s)
- Mercedes A H Warren Norris
- Department of Microbiology and Immunology, University of North Carolina at Chapel Hill School of Medicine, Chapel Hill, NC, USA
| | - Dylan M Plaskon
- Department of Microbiology and Immunology, University of North Carolina at Chapel Hill School of Medicine, Chapel Hill, NC, USA
| | - Rita Tamayo
- Department of Microbiology and Immunology, University of North Carolina at Chapel Hill School of Medicine, Chapel Hill, NC, USA.
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5
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Wetzel D, Carter ZA, Monteiro MP, Edwards AN, Scharer CD, McBride SM. The pH-responsive SmrR-SmrT system modulates C. difficile antimicrobial resistance, spore formation, and toxin production. Infect Immun 2024; 92:e0046123. [PMID: 38345371 PMCID: PMC10929453 DOI: 10.1128/iai.00461-23] [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: 11/07/2023] [Accepted: 01/23/2024] [Indexed: 02/27/2024] Open
Abstract
Clostridioides difficile is an anaerobic gastrointestinal pathogen that spreads through the environment as dormant spores. To survive, replicate, and sporulate in the host intestine, C. difficile must adapt to a variety of conditions in its environment, including changes in pH, the availability of metabolites, host immune factors, and a diverse array of other species. Prior studies showed that changes in intestinal conditions, such as pH, can affect C. difficile toxin production, spore formation, and cell survival. However, little is understood about the specific genes and pathways that facilitate environmental adaptation and lead to changes in C. difficile cell outcomes. In this study, we investigated two genes, CD2505 and CD2506, that are differentially regulated by pH to determine if they impact C. difficile growth and sporulation. Using deletion mutants, we examined the effects of both genes (herein smrR and smrT) on sporulation frequency, toxin production, and antimicrobial resistance. We determined that SmrR is a repressor of smrRT that responds to pH and suppresses sporulation and toxin production through regulation of the SmrT transporter. Further, we showed that SmrT confers resistance to erythromycin and lincomycin, establishing a connection between the regulation of sporulation and antimicrobial resistance.IMPORTANCEClostridioides difficile is a mammalian pathogen that colonizes the large intestine and produces toxins that lead to severe diarrheal disease. C. difficile is a major threat to public health due to its intrinsic resistance to antimicrobials and its ability to form dormant spores that are easily spread from host to host. In this study, we examined the contribution of two genes, smrR and smrT, on sporulation, toxin production, and antimicrobial resistance. Our results indicate that SmrR represses smrT expression, while production of SmrT increases spore and toxin production, as well as resistance to antibiotics.
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Affiliation(s)
- Daniela Wetzel
- Department of Microbiology and Immunology, Emory University School of Medicine, Emory Antibiotic Resistance Center, Atlanta, Georgia, USA
| | - Zavier A. Carter
- Department of Microbiology and Immunology, Emory University School of Medicine, Emory Antibiotic Resistance Center, Atlanta, Georgia, USA
| | - Marcos P. Monteiro
- Department of Microbiology and Immunology, Emory University School of Medicine, Emory Antibiotic Resistance Center, Atlanta, Georgia, USA
| | - Adrianne N. Edwards
- Department of Microbiology and Immunology, Emory University School of Medicine, Emory Antibiotic Resistance Center, Atlanta, Georgia, USA
| | - Christopher D. Scharer
- Department of Microbiology and Immunology, Emory University School of Medicine, Emory Antibiotic Resistance Center, Atlanta, Georgia, USA
| | - Shonna M. McBride
- Department of Microbiology and Immunology, Emory University School of Medicine, Emory Antibiotic Resistance Center, Atlanta, Georgia, USA
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6
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Furtado KL, Plott L, Markovetz M, Powers D, Wang H, Hill DB, Papin J, Allbritton NL, Tamayo R. Clostridioides difficile-mucus interactions encompass shifts in gene expression, metabolism, and biofilm formation. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.02.01.578425. [PMID: 38352512 PMCID: PMC10862863 DOI: 10.1101/2024.02.01.578425] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 02/25/2024]
Abstract
In a healthy colon, the stratified mucus layer serves as a crucial innate immune barrier to protect the epithelium from microbes. Mucins are complex glycoproteins that serve as a nutrient source for resident microflora and can be exploited by pathogens. We aimed to understand how the intestinal pathogen, Clostridioides diffiicile, independently uses or manipulates mucus to its benefit, without contributions from members of the microbiota. Using a 2-D primary human intestinal epithelial cell model to generate physiologic mucus, we assessed C. difficile-mucus interactions through growth assays, RNA-Seq, biophysical characterization of mucus, and contextualized metabolic modeling. We found that host-derived mucus promotes C. difficile growth both in vitro and in an infection model. RNA-Seq revealed significant upregulation of genes related to central metabolism in response to mucus, including genes involved in sugar uptake, the Wood-Ljungdahl pathway, and the glycine cleavage system. In addition, we identified differential expression of genes related to sensing and transcriptional control. Analysis of mutants with deletions in highly upregulated genes reflected the complexity of C. difficile-mucus interactions, with potential interplay between sensing and growth. Mucus also stimulated biofilm formation in vitro, which may in turn alter viscoelastic properties of mucus. Context-specific metabolic modeling confirmed differential metabolism and predicted importance of enzymes related to serine and glycine catabolism with mucus. Subsequent growth experiments supported these findings, indicating mucus is an important source of serine. Our results better define responses of C. difficile to human gastrointestinal mucus and highlight a flexibility in metabolism that may influence pathogenesis.
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Affiliation(s)
- Kathleen L. Furtado
- Department of Microbiology and Immunology, University of North Carolina at Chapel Hill School of Medicine, Chapel Hill, NC, USA
| | - Lucas Plott
- Marsico Lung Institute, University of North Carolina at Chapel Hill School of Medicine, Chapel Hill, NC, USA
| | - Matthew Markovetz
- Marsico Lung Institute, University of North Carolina at Chapel Hill School of Medicine, Chapel Hill, NC, USA
| | - Deborah Powers
- Department of Biochemistry and Molecular Genetics, University of Virginia, Charlottesville, VA, USA
| | - Hao Wang
- Department of Bioengineering, University of Washington, Seattle, WA, USA
| | - David B. Hill
- Marsico Lung Institute, University of North Carolina at Chapel Hill School of Medicine, Chapel Hill, NC, USA
- Joint Department of Biomedical Engineering, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
- Department of Physics and Astronomy, College of Arts and Sciences, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | - Jason Papin
- Department of Biochemistry and Molecular Genetics, University of Virginia, Charlottesville, VA, USA
- Department of Biomedical Engineering, University of Virginia, Charlottesville, VA, USA
- Department of Medicine, Division of Infectious Diseases and International Health, University of Virginia, Charlottesville, VA, USA
| | | | - Rita Tamayo
- Department of Microbiology and Immunology, University of North Carolina at Chapel Hill School of Medicine, Chapel Hill, NC, USA
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7
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Wetzel D, Carter ZA, Monteiro MP, Edwards AN, McBride SM. The pH-responsive SmrR-SmrT system modulates C. difficile antimicrobial resistance, spore formation, and toxin production. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.11.02.565354. [PMID: 37961610 PMCID: PMC10635087 DOI: 10.1101/2023.11.02.565354] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/15/2023]
Abstract
Clostridioides difficile is an anaerobic gastrointestinal pathogen that spreads through the environment as dormant spores. To survive, replicate, and sporulate in the host intestine, C. difficile must adapt to a variety of conditions in its environment, including changes in pH, the availability of metabolites, host immune factors, and a diverse array of other species. Prior studies showed that changes in intestinal conditions, such as pH, can affect C. difficile toxin production, spore formation, and cell survival. However, little is understood about the specific genes and pathways that facilitate environmental adaptation and lead to changes in C. difficile cell outcomes. In this study, we investigated two genes, CD2505 and CD2506, that are differentially regulated by pH to determine if they impact C. difficile growth and sporulation. Using deletion mutants, we examined the effects of both genes (herein smrR and smrT ) on sporulation frequency, toxin production, and antimicrobial resistance. We determined that SmrR is a repressor of smrRT that responds to pH and suppresses sporulation and toxin production through regulation of the SmrT transporter. Further, we showed that SmrT confers resistance to erythromycin and lincomycin, establishing a connection between the regulation of sporulation and antimicrobial resistance. IMPORTANCE C. difficile is a mammalian pathogen that colonizes the large intestine and produces toxins that lead to severe diarrheal disease. C. difficile is a major threat to public health due to its intrinsic resistance to antimicrobials and its ability to form dormant spores that are easily spread from host to host. In this study, we examined the contribution of two genes, smrR and smrT on sporulation, toxin production, and antimicrobial resistance. Our results indicate that SmrR represses smrT expression, while production of SmrT increases spore and toxin production, as well as resistance to antibiotics.
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8
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García C, Hinostroza N, Gordillo V, Inchaustegui ML, Astocondor L, Chincha O, Alejos S, Olivera M, Bojórquez-Fernández D, Concha-Velasco F, Vásquez N, Castaneda-Sabogal A, Sullón P, Fernández V, Villegas-Chiroque M, López E, Hueda-Zavaleta M, Vidaurre A, Bocángel C, Barco E, Paricahua E, Zervos M, Jacobs J, Krapp F. Methicillin-Resistant Staphylococcus aureus Bloodstream Infections in Hospitalized Patients in Peru. Am J Trop Med Hyg 2023; 109:1118-1121. [PMID: 37722664 PMCID: PMC10622478 DOI: 10.4269/ajtmh.23-0054] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2023] [Accepted: 07/16/2023] [Indexed: 09/20/2023] Open
Abstract
There is a knowledge gap in the epidemiology of methicillin-resistant Staphylococcus aureus (MRSA) causing bloodstream infections (BSIs) in Peru. Through a surveillance study in 13 hospitals of 10 Peruvian regions (2017-2019), we assessed the proportion of MRSA among S. aureus BSIs as well as the molecular typing of the isolates. A total of 166 S. aureus isolates were collected, and 36.1% of them were MRSA. Of note, MRSA isolates with phenotypic and genetic characteristics of the hospital-associated Chilean-Cordobes clone (multidrug-resistant SCCmec I, non-Panton-Valentine leukocidin [PVL] producers) were most commonly found (70%), five isolates with genetic characteristics of community-associated MRSA (CA-MRSA)-SCCmec IV, PVL-producer-(8.3%) were seen in three separate regions. These results demonstrate that hospital-associated MRSA is the most frequent MRSA found in patients with BSIs in Peru. They also show the emergence of S. aureus with genetic characteristics of CA-MRSA. Further studies are needed to evaluate the extension of CA-MRSA dissemination in Peru.
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Affiliation(s)
- Coralith García
- Instituto de Medicina Tropical Alexander von Humboldt, Universidad Peruana Cayetano Heredia, Lima, Peru
- Facultad de Medicina, Universidad Peruana Cayetano Heredia, Lima, Peru
- Departamento de Enfermedades Infecciosas, Tropicales y Dermatológicas, Hospital Cayetano Heredia, Lima, Peru
| | - Noemí Hinostroza
- Instituto de Medicina Tropical Alexander von Humboldt, Universidad Peruana Cayetano Heredia, Lima, Peru
| | - Valeria Gordillo
- Facultad de Medicina, Universidad Peruana Cayetano Heredia, Lima, Peru
| | | | - Lizeth Astocondor
- Instituto de Medicina Tropical Alexander von Humboldt, Universidad Peruana Cayetano Heredia, Lima, Peru
| | - Omayra Chincha
- Instituto de Medicina Tropical Alexander von Humboldt, Universidad Peruana Cayetano Heredia, Lima, Peru
- Departamento de Enfermedades Infecciosas, Tropicales y Dermatológicas, Hospital Cayetano Heredia, Lima, Peru
| | - Saúl Alejos
- Instituto de Medicina Tropical Alexander von Humboldt, Universidad Peruana Cayetano Heredia, Lima, Peru
| | - Marco Olivera
- Servicio de Infectología y Medicina Tropical, Hospital María Auxiliadora, Lima, Peru
| | | | - Fátima Concha-Velasco
- Departamento de Medicina, Hospital Antonio Lorena, Cusco, Peru
- Escuela Profesional de Medicina Humana, Universidad Nacional San Antonio Abad del Cusco, Cusco, Peru
| | - Nancy Vásquez
- Departamento de Apoyo al Diagnóstico, Hospital Antonio Lorena, Cusco, Peru
| | - Alex Castaneda-Sabogal
- Departamento de Medicina, Hospital Base Víctor Lazarte Echegaray de EsSalud, La Libertad, Peru
- Facultad de Medicina Humana, Universidad Privada Antenor Orrego, Trujillo, Peru
| | - Pedro Sullón
- Departamento de Especilaidades Médicas, Hospital Hipólito Unanue, Lima, Peru
| | - Víctor Fernández
- Departamento de Medicina, Hospital Belén de Trujillo, La Libertad, Peru
| | | | - Enrique López
- Departamento de Medicina Hospital Regional de Loreto Felipe Santiago Arriola Iglesias, Loreto, Peru
| | - Miguel Hueda-Zavaleta
- Faculty of Health Sciences, Universidad Privada de Tacna, Tacna, Peru
- Departamento de Medicina, Hospital III Daniel Alcides Carrión–EsSalud Tacna, Tacna, Peru
| | - Ana Vidaurre
- Departamento de Medicina, Hospital III EsSalud Chimbote, Ancash, Peru
| | - César Bocángel
- Departamento de Medicina Hospital Goyeneche de Arequipa, Arequipa, Peru
| | - Evelyn Barco
- Departamento de Patología Clínica, Hospital Regional II-2 José Alfredo Mendoza Olavarría, Tumbes, Peru
| | - Eduardo Paricahua
- Departamento de Medicina, Hospital Santa Rosa de Puerto Maldonado, Madre de Dios, Peru
| | - Marcus Zervos
- Infectious Disease Division, Henry Ford Health System, Detroit, Michigan
| | - Jan Jacobs
- Institute of Tropical Medicine, Antwerp, Belgium
- Department of Microbiology, Immunology and Transplantation, KU Leuven, Belgium
| | - Fiorella Krapp
- Instituto de Medicina Tropical Alexander von Humboldt, Universidad Peruana Cayetano Heredia, Lima, Peru
- Facultad de Medicina, Universidad Peruana Cayetano Heredia, Lima, Peru
- Department of Microbiology, Immunology and Transplantation, KU Leuven, Belgium
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9
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Rizvi A, Vargas-Cuebas G, Edwards AN, DiCandia MA, Carter ZA, Lee CD, Monteiro MP, McBride SM. Glycine fermentation by C. difficile promotes virulence and spore formation, and is induced by host cathelicidin. Infect Immun 2023; 91:e0031923. [PMID: 37754683 PMCID: PMC10580938 DOI: 10.1128/iai.00319-23] [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: 08/11/2023] [Accepted: 08/14/2023] [Indexed: 09/28/2023] Open
Abstract
Clostridioides difficile is a leading cause of antibiotic-associated diarrheal disease. C. difficile colonization, growth, and toxin production in the intestine is strongly associated with its ability to use amino acids to generate energy, but little is known about the impact of specific amino acids on C. difficile pathogenesis. The amino acid glycine is enriched in the dysbiotic gut and is suspected to contribute to C. difficile infection. We hypothesized that the use of glycine as an energy source contributes to colonization of the intestine and pathogenesis of C. difficile. To test this hypothesis, we deleted the glycine reductase (GR) genes grdAB, rendering C. difficile unable to ferment glycine, and investigated the impact on growth and pathogenesis. Our data show that the grd pathway promotes growth, toxin production, and sporulation. Glycine fermentation also had a significant impact on toxin production and pathogenesis of C. difficile in the hamster model of disease. Furthermore, we determined that the grd locus is regulated by host cathelicidin (LL-37) and the cathelicidin-responsive regulator, ClnR, indicating that the host peptide signals to control glycine catabolism. The induction of glycine fermentation by LL-37 demonstrates a direct link between the host immune response and the bacterial reactions of toxin production and spore formation.
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Affiliation(s)
- Arshad Rizvi
- Department of Microbiology and Immunology, Emory University School of Medicine, Emory Antibiotic Resistance Center, Atlanta, Georgia, USA
| | - Germán Vargas-Cuebas
- Department of Microbiology and Immunology, Emory University School of Medicine, Emory Antibiotic Resistance Center, Atlanta, Georgia, USA
| | - Adrianne N. Edwards
- Department of Microbiology and Immunology, Emory University School of Medicine, Emory Antibiotic Resistance Center, Atlanta, Georgia, USA
| | - Michael A. DiCandia
- Department of Microbiology and Immunology, Emory University School of Medicine, Emory Antibiotic Resistance Center, Atlanta, Georgia, USA
| | - Zavier A. Carter
- Department of Microbiology and Immunology, Emory University School of Medicine, Emory Antibiotic Resistance Center, Atlanta, Georgia, USA
| | - Cheyenne D. Lee
- Department of Microbiology and Immunology, Emory University School of Medicine, Emory Antibiotic Resistance Center, Atlanta, Georgia, USA
| | - Marcos P. Monteiro
- Department of Microbiology and Immunology, Emory University School of Medicine, Emory Antibiotic Resistance Center, Atlanta, Georgia, USA
| | - Shonna M. McBride
- Department of Microbiology and Immunology, Emory University School of Medicine, Emory Antibiotic Resistance Center, Atlanta, Georgia, USA
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10
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DiCandia MA, Edwards AN, Lee CD, Monteiro MP, Cuebas GNV, Bagchi P, McBride SM. A Conserved Switch Controls Virulence, Sporulation, and Motility in C. difficile. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.03.28.534590. [PMID: 37034656 PMCID: PMC10081167 DOI: 10.1101/2023.03.28.534590] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/19/2023]
Abstract
Spore formation is required for environmental survival and transmission of the human enteropathogenic Clostridioides difficile . In all bacterial spore formers, sporulation is regulated through activation of the master response regulator, Spo0A. However, the factors and mechanisms that directly regulate C. difficile Spo0A activity are not defined. In the well-studied Bacillus species, Spo0A is directly inactivated by Spo0E, a small phosphatase. To understand Spo0E function in C. difficile , we created a null mutation of the spo0E ortholog and assessed sporulation and physiology. The spo0E mutant produced significantly more spores, demonstrating Spo0E represses C. difficile sporulation. Unexpectedly, the spo0E mutant also exhibited increased motility and toxin production, and enhanced virulence in animal infections. We uncovered that Spo0E interacts with both Spo0A and the toxin and motility regulator, RstA. Direct interactions between Spo0A, Spo0E, and RstA constitute a previously unknown molecular switch that coordinates sporulation with motility and toxin production. Reinvestigation of Spo0E function in B. subtilis revealed that Spo0E induced motility, demonstrating Spo0E regulation of motility and sporulation among divergent species. Further, we found that Spo0E orthologs are widespread among prokaryotes, suggesting that Spo0E performs conserved regulatory functions in diverse bacteria.
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11
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Plasmid Sequence and Availability for an Improved Clostridioides difficile CRISPR-Cas9 Mutagenesis System. Microbiol Resour Announc 2022; 11:e0083322. [PMID: 36342279 PMCID: PMC9753633 DOI: 10.1128/mra.00833-22] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
A two-plasmid mutagenesis system for Clostridioides difficile is described that improves ease of use and efficiency in creating site-directed mutations. pJB06 contains a xylose-inducible cas9 gene, while the second plasmid (pJB07) encodes the corresponding guide RNA (gRNA) and regions of homology for repair of the introduced double-stranded DNA (dsDNA) breaks, both of which are replaceable via restriction digest.
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12
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BELITSKY BORISR. VanG- and D-Ala-D-Ser-dependent peptidoglycan synthesis and vancomycin resistance in Clostridioides difficile. Mol Microbiol 2022; 118:526-540. [PMID: 36065735 PMCID: PMC9671823 DOI: 10.1111/mmi.14980] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2022] [Revised: 08/30/2022] [Accepted: 09/02/2022] [Indexed: 11/29/2022]
Abstract
A Clostridioides difficile strain deficient in the ddl gene is unable to synthesize the dipeptide D-Ala-D-Ala, an essential component of peptidoglycan and the target of vancomycin. We isolated spontaneous suppressors of a ∆ddl mutation that allowed cell growth in the absence of D-Ala-D-Ala. The mutations caused constitutive or partly constitutive expression of the vancomycin-inducible vanG operon responsible for the synthesis of D-Ala-D-Ser, which can replace D-Ala-D-Ala in peptidoglycan. The mutations mapped to the vanS or vanR genes, which regulate expression of the vanG operon. The constitutive level of vanG expression was about 10-fold above that obtained by vancomycin induction. The incorporation of D-Ala-D-Ser into peptidoglycan due to high expression of the vanG operon conferred only low-level resistance to vancomycin, but VanG was found to synthesize D-Ala-D-Ala in addition to D-Ala-D-Ser. However, the same, low resistance to vancomycin was also observed in cells completely unable to synthesize D-Ala-D-Ala and grown in the presence of D-Ala-D-Ser. D-Ala-D-Ala presence was required for efficient vancomycin induction of the vanG operon showing that vancomycin is not by itself able to activate VanS. D-Ala-D-Ser, similar to D-Ala-D-Ala, served as an anti-activator of DdlR, the positive regulator of the ddl gene, thereby coupling vanG and ddl expression.
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Affiliation(s)
- BORIS R. BELITSKY
- Department of Molecular Biology and Microbiology, Tufts University School of Medicine, Boston, Massachusetts 02111, USA
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13
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Jing W, Pilato JL, Kay C, Feng S, Tuipulotu DE, Mathur A, Shen C, Ngo C, Zhao A, Miosge LA, Ali SA, Gardiner EE, Awad MM, Lyras D, Robertson AAB, Kaakoush NO, Man SM. Clostridium septicum α-toxin activates the NLRP3 inflammasome by engaging GPI-anchored proteins. Sci Immunol 2022; 7:eabm1803. [PMID: 35594341 DOI: 10.1126/sciimmunol.abm1803] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Clostridium species are a group of Gram-positive bacteria that cause diseases in humans, such as food poisoning, botulism, and tetanus. Here, we analyzed 10 different Clostridium species and identified that Clostridium septicum, a pathogen that causes sepsis and gas gangrene, activates the mammalian cytosolic inflammasome complex in mice and humans. Mechanistically, we demonstrate that α-toxin secreted by C. septicum binds to glycosylphosphatidylinositol (GPI)-anchored proteins on the host plasma membrane, oligomerizing and forming a membrane pore that is permissive to efflux of magnesium and potassium ions. Efflux of these cytosolic ions triggers the activation of the innate immune sensor NLRP3, inducing activation of caspase-1 and gasdermin D, secretion of the proinflammatory cytokines interleukin-1β and interleukin-18, pyroptosis, and plasma membrane rupture via ninjurin-1. Furthermore, α-toxin of C. septicum induces rapid inflammasome-mediated lethality in mice and pharmacological inhibition of the NLRP3 inflammasome using MCC950 prevents C. septicum-induced lethality. Overall, our results reveal that cytosolic innate sensing of α-toxin is central to the recognition of C. septicum infection and that therapeutic blockade of the inflammasome pathway may prevent sepsis and death caused by toxin-producing pathogens.
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Affiliation(s)
- Weidong Jing
- Division of Immunity, Inflammation and Infection, The John Curtin School of Medical Research, The Australian National University, Canberra, Australia
| | - Jordan Lo Pilato
- Division of Immunity, Inflammation and Infection, The John Curtin School of Medical Research, The Australian National University, Canberra, Australia
| | - Callum Kay
- Division of Immunity, Inflammation and Infection, The John Curtin School of Medical Research, The Australian National University, Canberra, Australia
| | - Shouya Feng
- Division of Immunity, Inflammation and Infection, The John Curtin School of Medical Research, The Australian National University, Canberra, Australia
| | - Daniel Enosi Tuipulotu
- Division of Immunity, Inflammation and Infection, The John Curtin School of Medical Research, The Australian National University, Canberra, Australia
| | - Anukriti Mathur
- Division of Immunity, Inflammation and Infection, The John Curtin School of Medical Research, The Australian National University, Canberra, Australia
| | - Cheng Shen
- Division of Immunity, Inflammation and Infection, The John Curtin School of Medical Research, The Australian National University, Canberra, Australia
| | - Chinh Ngo
- Division of Immunity, Inflammation and Infection, The John Curtin School of Medical Research, The Australian National University, Canberra, Australia
| | - Anyang Zhao
- Division of Immunity, Inflammation and Infection, The John Curtin School of Medical Research, The Australian National University, Canberra, Australia
| | - Lisa A Miosge
- Division of Immunity, Inflammation and Infection, The John Curtin School of Medical Research, The Australian National University, Canberra, Australia
| | - Sidra A Ali
- Division of Genome Science and Cancer, The John Curtin School of Medical Research, The Australian National University, Canberra, Australia
| | - Elizabeth E Gardiner
- Division of Genome Science and Cancer, The John Curtin School of Medical Research, The Australian National University, Canberra, Australia
| | - Milena M Awad
- Infection and Immunity Program and Department of Microbiology, Monash Biomedicine Discovery Institute, Monash University, Clayton, Australia
| | - Dena Lyras
- Infection and Immunity Program and Department of Microbiology, Monash Biomedicine Discovery Institute, Monash University, Clayton, Australia
| | - Avril A B Robertson
- School of Chemistry and Molecular Biosciences, The University of Queensland, Brisbane, Australia
| | | | - Si Ming Man
- Division of Immunity, Inflammation and Infection, The John Curtin School of Medical Research, The Australian National University, Canberra, Australia
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14
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Draft Genome Sequence of Clostridium bowmanii DSM 14206 T, Isolated from an Antarctic Microbial Mat. Microbiol Resour Announc 2022; 11:e0103521. [PMID: 34989621 PMCID: PMC8759372 DOI: 10.1128/mra.01035-21] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Clostridium bowmanii type strain DSM 14206 (ATCC BAA-581) was isolated from a microbial mat sample retrieved from Lake Fryxell, Antarctica. This report describes the generation and annotation of the 4.9-Mb draft genome sequence of C. bowmanii DSM 14206T.
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15
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Romo JA, Kumamoto CA. Characterization of the Effects of Candida Gastrointestinal Colonization on Clostridioides difficile Infection in a Murine Model. Methods Mol Biol 2022; 2542:271-285. [PMID: 36008672 DOI: 10.1007/978-1-0716-2549-1_20] [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: 06/15/2023]
Abstract
The role of fungal colonizers of the gastrointestinal tract during disease states is not well understood. Antibiotic treatment renders patients highly susceptible to infection by the bacterial pathogen C. difficile while also leading to blooms in fungal commensals, setting the stage for trans-kingdom interactions. Here, we describe a murine model of Candida gastrointestinal colonization coupled to a C. difficile infection (CDI) model, the measurement of CFU of both organisms, and collection of cecum and colon contents for the purpose of quantifying C. difficile toxin production. Additionally, we describe how to induce and purify C. difficile spores.
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Affiliation(s)
- Jesús A Romo
- Department of Molecular Biology and Microbiology, Tufts University School of Medicine, Boston, MA, USA
| | - Carol A Kumamoto
- Department of Molecular Biology and Microbiology, Tufts University School of Medicine, Boston, MA, USA.
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16
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Identification of ClpP Dual Isoform Disruption as an Anti-sporulation Strategy for Clostridioides difficile. J Bacteriol 2021; 204:e0041121. [PMID: 34807726 DOI: 10.1128/jb.00411-21] [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
The Gram-positive bacterium Clostridioides difficile is a primary cause of hospital-acquired diarrhea, threatening both immunocompromised and healthy individuals. An important aspect of defining mechanisms that drive C. difficile persistence and virulence relies on developing a more complete understanding of sporulation. C. difficile sporulation is the single determinant of transmission and complicates treatment and prevention due to the chemical and physical resilience of spores. By extension, the identification of druggable targets that significantly attenuate sporulation would have a significant impact on thwarting C. difficile infection. Using a new CRISPR-Cas9 nickase genome editing methodology, stop codons were inserted early in the coding sequence for clpP1 and clpP2 to generate C. difficile mutants that no longer produced the corresponding isoforms of caseinolytic protease P (ClpP). The data show that genetic ablation of ClpP isoforms leads to altered sporulation phenotypes with the clpP1/clpP2 double mutant exhibiting asporogenic behavior. A small screen of known ClpP inhibitors in a fluorescence-based biochemical assay identified bortezomib as an inhibitor of C. difficile ClpP that produces dose-dependent inhibition of purified ClpP. Incubation of C. difficile cultures in the presence of bortezomib reveals anti-sporulation effects approaching that observed in the clpP1/clpP2 double mutant. This work identifies ClpP as a key contributor to C. difficile sporulation and provides compelling support for the pursuit of small molecule ClpP inhibitors as C. difficile anti-sporulating agents. IMPORTANCE Due to diverse roles of ClpP and the reliance of pathogens upon this system for infection, it has emerged as a target for antimicrobial development. Biology regulated by ClpP is organism-dependent and has not been defined in C. difficile. This work identifies ClpP as a key contributor to C. difficile sporulation and provides compelling support for the pursuit of small molecule ClpP inhibitors as anti-sporulating agents. The identification of new approaches and/or drug targets that reduce C. difficile sporulation would be transformative and are expected to find high utility in prophylaxis, transmission attenuation, and relapse prevention. Discovery of the ClpP system as a major driver to sporulation also provides a new avenue of inquiry for advancing the understanding of sporulation.
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17
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Jones JB, Liu L, Rank LA, Wetzel D, Woods EC, Biok N, Anderson SE, Lee MR, Liu R, Huth S, Sandhu BK, Gellman SH, McBride SM. Cationic Homopolymers Inhibit Spore and Vegetative Cell Growth of Clostridioides difficile. ACS Infect Dis 2021; 7:1236-1247. [PMID: 33739823 PMCID: PMC8130196 DOI: 10.1021/acsinfecdis.0c00843] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
A wide range of synthetic polymers have been explored for antimicrobial activity. These materials usually contain both cationic and hydrophobic subunits because these two characteristics are prominent among host-defense peptides. Here, we describe a series of nylon-3 polymers containing only cationic subunits and their evaluation against the gastrointestinal, spore-forming pathogen Clostridioides difficile. Despite their highly hydrophilic nature, these homopolymers showed efficacy against both the vegetative and spore forms of the bacterium, including an impact on C. difficile spore germination. The polymer designated P34 demonstrated the greatest efficacy against C. difficile strains, along with low propensities to lyse human red blood cells or intestinal epithelial cells. To gain insight into the mechanism of P34 action, we evaluated several cell-surface mutant strains of C. difficile to determine the impacts on growth, viability, and cell morphology. The results suggest that P34 interacts with the cell wall, resulting in severe cell bending and death in a concentration-dependent manner. The unexpected finding that nylon-3 polymers composed entirely of cationic subunits display significant activities toward C. difficile should expand the range of other polymers considered for antibacterial applications.
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Affiliation(s)
- Joshua B. Jones
- Department of Microbiology and Immunology, Emory University School of Medicine, Emory Antibiotic Resistance Center, Atlanta, GA, USA
| | - Lei Liu
- Department of Chemistry and Department of Medicine, University of Wisconsin, Madison, WI, USA
| | | | - Daniela Wetzel
- Department of Microbiology and Immunology, Emory University School of Medicine, Emory Antibiotic Resistance Center, Atlanta, GA, USA
| | - Emily C. Woods
- Department of Medicine, Stanford University School of Medicine, Stanford, CA, USA
| | - Naomi Biok
- Department of Chemistry and Department of Medicine, University of Wisconsin, Madison, WI, USA
| | | | - Myung-ryul Lee
- Department of Chemistry, University of Illinois at Urbana-Champaign, Urbana, IL, USA
| | - Runhui Liu
- State Key Laboratory of Bioreactor Engineering, School of Materials Science and Engineering, East China University of Science and Technology, Shanghai, China
| | - Sean Huth
- Department of Chemistry, Princeton University, Princeton, NJ, USA
| | - Brindar K. Sandhu
- Department of Microbiology and Immunology, Emory University School of Medicine, Emory Antibiotic Resistance Center, Atlanta, GA, USA
| | - Samuel H. Gellman
- Department of Chemistry and Department of Medicine, University of Wisconsin, Madison, WI, USA
| | - Shonna M. McBride
- Department of Microbiology and Immunology, Emory University School of Medicine, Emory Antibiotic Resistance Center, Atlanta, GA, USA
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18
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Multiple Regulatory Mechanisms Control the Production of CmrRST, an Atypical Signal Transduction System in Clostridioides difficile. mBio 2021; 13:e0296921. [PMID: 35164558 PMCID: PMC8844915 DOI: 10.1128/mbio.02969-21] [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] [Indexed: 12/16/2022] Open
Abstract
Clostridioides difficile, an intestinal pathogen and leading cause of nosocomial infection, exhibits extensive phenotypic heterogeneity through phase variation. The signal transduction system CmrRST, which encodes two response regulators (CmrR and CmrT) and a sensor kinase (CmrS), impacts C. difficile cell and colony morphology, surface and swimming motility, biofilm formation, and virulence in an animal model. CmrRST is subject to phase variation through site-specific recombination and reversible inversion of the "cmr switch," and expression of cmrRST is also regulated by cyclic diguanylate (c-di-GMP) through a riboswitch. The goal of this study was to determine how the cmr switch and c-di-GMP work together to regulate cmrRST expression. We generated "phase-locked" strains by mutating key residues in the right inverted repeat flanking the cmr switch. Phenotypic characterization of these phase-locked cmr-ON and -OFF strains demonstrates that they cannot switch between rough and smooth colony morphologies, respectively, or other CmrRST-associated phenotypes. Manipulation of c-di-GMP levels in these mutants showed that c-di-GMP promotes cmrRST expression and associated phenotypes independently of cmr switch orientation. We identified multiple promoters controlling cmrRST transcription, including one within the ON orientation of the cmr switch and another that is positively autoregulated by CmrR. Overall, this work reveals a complex regulatory network that governs cmrRST expression and a unique intersection of phase variation and c-di-GMP signaling. These findings suggest that multiple environmental signals impact the production of this signaling transduction system. IMPORTANCE Clostridioides difficile is a leading cause of hospital-acquired intestinal infections in the United States. The CmrRST signal transduction system controls numerous physiological traits and processes in C. difficile, including cell and colony morphology, motility, biofilm formation, and virulence. Here, we define the complex, multilevel regulation of cmrRST expression, including stochastic control through phase variation, modulation by the second messenger c-di-GMP, and positive autoregulation by CmrR. The results of this study suggest that multiple, distinct environmental stimuli and selective pressures must be integrated to appropriately control cmrRST expression.
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19
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Combined and Distinct Roles of Agr Proteins in Clostridioides difficile 630 Sporulation, Motility, and Toxin Production. mBio 2020; 11:mBio.03190-20. [PMID: 33443122 PMCID: PMC8534292 DOI: 10.1128/mbio.03190-20] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The Clostridioides difficile accessory gene regulator 1 (agr1) locus consists of two genes, agrB1 and agrD1, that presumably constitute an autoinducing peptide (AIP) system. Typically, AIP systems function through the AgrB-mediated processing of AgrD to generate a processed form of the AIP that provides a concentration-dependent extracellular signal. Here, we show that the C. difficile 630 Agr1 system has multiple functions, not all of which depend on AgrB1. CRISPR-Cas9n deletion of agrB1, agrD1, or the entire locus resulted in changes in transcription of sporulation-related factors and an overall loss in spore formation. Sporulation was recovered in the mutants by providing supernatant from stationary-phase cultures of the parental strain. In contrast, C. difficile motility was reduced only when both AgrB1 and AgrD1 were disrupted. Finally, in the absence of AgrB1, the AgrD1 peptide accumulated within the cytoplasm and this correlated with increased expression of tcdR (15-fold), as well as tcdA (20-fold) and tcdB (5-fold), which encode the two major C. difficile toxins. The combined deletion of agrB1/agrD1 or deletion of only agrD1 did not significantly alter expression of tcdR or tcdB but did show a minor effect on tcdA expression. Overall, these data indicate that the Agr1-based system in C. difficile 630 carries out multiple functions, some of which are associated with prototypical AIP signaling and others of which involve previously undescribed mechanisms of action.IMPORTANCE C. difficile is a spore-forming, toxigenic, anaerobic bacterium that causes severe gastrointestinal illness. Understanding the ways in which C. difficile senses growth conditions to regulate toxin expression and sporulation is essential to advancing our understanding of this pathogen. The Agr1 system in C. difficile has been thought to function by generating an extracellular autoinducing peptide that accumulates and exogenously activates two-component signaling. The absence of the peptide or protease should, in theory, result in similar phenotypes. However, in contrast to longstanding assumptions about Agr, we found that mutants of individual agr1 genes exhibit distinct phenotypes in C. difficile These findings suggest that the Agr1 system may have other regulatory mechanisms independent of the typical Agr quorum sensing system. These data not only challenge models for Agr's mechanism of action in C. difficile but also may expand our conceptions of how this system works in other Gram-positive pathogens.
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20
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Kinoshita Y, Takechi M, Uchida-Fujii E, Miyazawa K, Nukada T, Niwa H. Ten cases of Mycobacterium avium subsp. hominissuis infections linked to equine abortions in Japan, 2018-2019. Vet Med Sci 2020; 7:621-625. [PMID: 33336899 PMCID: PMC8136959 DOI: 10.1002/vms3.411] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2019] [Revised: 06/15/2020] [Accepted: 12/01/2020] [Indexed: 02/06/2023] Open
Abstract
Bacterial placentitis in horses commonly results in abortion, premature birth or compromised neonatal foal health. Although mycobacterial infections are generally uncommon in horses, 10 equine abortion cases caused by Mycobacterium avium subsp. hominissuis (MAH) infections occurred between 2018 and 2019 in Japan. They occurred on seven Thoroughbred horse farms in the Hidaka district of Hokkaido, but direct contact among the mares on different farms was not recorded. Most cases were characterized by extensive pathological lesions of the placenta, which are not typical in cases of common pathogenic bacteria such as Streptococcus zooepidemicus and Escherichia coli. All abortions featured white–yellow exudates on the surface of the placenta. Mycobacterial granuloma formations were histologically found in the placenta and fetal organs, and acid‐fast bacteria were isolated from the placenta, fetal samples (heart, lung, liver, kidney, spleen and stomach contents) or uterine lavage fluid. The greatest number of bacteria was isolated from necrotic lesions on the placenta, which could be an important site for bacterial isolation in mycobacterial equine abortions. The isolates were identified as MAH based on internal genome sequences. In variable number tandem repeat analysis, all patterns of the strains were identical. Single nucleotide polymorphism analysis of the core genome grouped all strains in the II‐a/SC3 subcluster. Both results reveal that these strains share the same genetic background, suggesting that the horses had been infected by the same unknown contagious source.
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Affiliation(s)
- Yuta Kinoshita
- Microbiology Division, Equine Research Institute, Japan Racing Association, Shimotsuke, Japan
| | - Mari Takechi
- Hokkaido Hidaka Livestock Hygiene Service Center, Hidakagunshinhidakacho, Japan
| | - Eri Uchida-Fujii
- Microbiology Division, Equine Research Institute, Japan Racing Association, Shimotsuke, Japan
| | - Kunio Miyazawa
- Hokkaido Hidaka Livestock Hygiene Service Center, Hidakagunshinhidakacho, Japan
| | - Toshio Nukada
- Microbiology Division, Equine Research Institute, Japan Racing Association, Shimotsuke, Japan
| | - Hidekazu Niwa
- Microbiology Division, Equine Research Institute, Japan Racing Association, Shimotsuke, Japan
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21
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Maslanka JR, Gu CH, Zarin I, Denny JE, Broadaway S, Fett B, Mattei LM, Walk ST, Abt MC. Detection and elimination of a novel non-toxigenic Clostridioides difficile strain from the microbiota of a mouse colony. Gut Microbes 2020; 12:1-15. [PMID: 33305657 PMCID: PMC7734020 DOI: 10.1080/19490976.2020.1851999] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
Clostridioides difficile is an enteric bacterial pathogen that can a cause nosocomial infection leading to debilitating colitis. The development of a murine model of C. difficile infection has led to fundamental discoveries in disease pathogenesis and the host immune response to infection. Recently, C. difficile endogenously present in the microbiota of mice has been reported and was found to complicate interpretation of mouse studies. Here, we report a novel C. difficile strain, named NTCD-035, isolated from the microbiota of our mouse colony. The presence of NTCD-035 in mice prior to challenge with a highly pathogenic C. difficile strain (VPI10463) led to significantly reduced disease severity. Phylogenetic characterization derived from whole genome sequencing and PCR ribotyping identified the isolate as a novel clade 1, ribotype 035 strain that lacks the pathogenicity locus required to produce toxins. Deficiency in toxin production along with sporulation capacity and secondary bile acid sensitivity was confirmed using in vitro assays. Inoculation of germ-free mice with NTCD-035 did not cause morbidity despite the strain readily colonizing the large intestine. Implementation of a culture-based screening procedure enabled the identification of mice harboring C. difficile in their microbiota, the establishment of a C. difficile-free mouse colony, and a monitoring system to prevent future contamination. Taken together, these data provide a framework for screening mice for endogenously harbored C. difficile and support clinical findings that demonstrate the therapeutic potential of non-toxigenic strains in preventing C. difficile associated disease. Abbreviations: PaLoc - Pathogenicity locus, CFUs - Colony forming units, TcdA - toxin-A, TcdB - toxin-B, CdtA - binary toxin A, CdtB - binary toxin B, CdtR - binary toxin R, NTCD - non-toxigenic C. difficile.
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Affiliation(s)
- Jeffrey R. Maslanka
- Department of Microbiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Christopher H. Gu
- Department of Microbiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Isma Zarin
- Department of Microbiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Joshua E. Denny
- Department of Microbiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Susan Broadaway
- Department of Microbiology and Immunology, Montana State University, Bozeman, MT, USA
| | - Bryton Fett
- Division of Gastroenterology, Hepatology and Nutrition, Children’s Hospital of Philadelphia, Philadelphia, PA, USA
| | - Lisa M. Mattei
- Division of Gastroenterology, Hepatology and Nutrition, Children’s Hospital of Philadelphia, Philadelphia, PA, USA
| | - Seth T. Walk
- Department of Microbiology and Immunology, Montana State University, Bozeman, MT, USA
| | - Michael C. Abt
- Department of Microbiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA,CONTACT Michael C Abt Department of Microbiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
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Bilverstone TW, Garland M, Cave RJ, Kelly ML, Tholen M, Bouley DM, Kaye P, Minton NP, Bogyo M, Kuehne SA, Melnyk RA. The glucosyltransferase activity of C. difficile Toxin B is required for disease pathogenesis. PLoS Pathog 2020; 16:e1008852. [PMID: 32960931 PMCID: PMC7531778 DOI: 10.1371/journal.ppat.1008852] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2020] [Revised: 10/02/2020] [Accepted: 08/03/2020] [Indexed: 01/01/2023] Open
Abstract
Enzymatic inactivation of Rho-family GTPases by the glucosyltransferase domain of Clostridioides difficile Toxin B (TcdB) gives rise to various pathogenic effects in cells that are classically thought to be responsible for the disease symptoms associated with C. difficile infection (CDI). Recent in vitro studies have shown that TcdB can, under certain circumstances, induce cellular toxicities that are independent of glucosyltransferase (GT) activity, calling into question the precise role of GT activity. Here, to establish the importance of GT activity in CDI disease pathogenesis, we generated the first described mutant strain of C. difficile producing glucosyltransferase-defective (GT-defective) toxin. Using allelic exchange (AE) technology, we first deleted tcdA in C. difficile 630Δerm and subsequently introduced a deactivating D270N substitution in the GT domain of TcdB. To examine the role of GT activity in vivo, we tested each strain in two different animal models of CDI pathogenesis. In the non-lethal murine model of infection, the GT-defective mutant induced minimal pathology in host tissues as compared to the profound caecal inflammation seen in the wild-type and 630ΔermΔtcdA (ΔtcdA) strains. In the more sensitive hamster model of CDI, whereas hamsters in the wild-type or ΔtcdA groups succumbed to fulminant infection within 4 days, all hamsters infected with the GT-defective mutant survived the 10-day infection period without primary symptoms of CDI or evidence of caecal inflammation. These data demonstrate that GT activity is indispensable for disease pathogenesis and reaffirm its central role in disease and its importance as a therapeutic target for small-molecule inhibition.
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Affiliation(s)
- Terry W. Bilverstone
- Clostridia Research Group, BBSRC/EPSRC Synthetic Biology Research Centre, School of Life Sciences, Centre for Biomolecular Sciences, The University of Nottingham, Nottingham, United kingdom
| | - Megan Garland
- Cancer Biology Program, Stanford School of Medicine, Stanford, CA, United States of America
- Department of Pathology, Stanford School of Medicine, Stanford, CA, United States of America
| | - Rory J. Cave
- Clostridia Research Group, BBSRC/EPSRC Synthetic Biology Research Centre, School of Life Sciences, Centre for Biomolecular Sciences, The University of Nottingham, Nottingham, United kingdom
| | - Michelle L. Kelly
- Clostridia Research Group, BBSRC/EPSRC Synthetic Biology Research Centre, School of Life Sciences, Centre for Biomolecular Sciences, The University of Nottingham, Nottingham, United kingdom
| | - Martina Tholen
- Department of Pathology, Stanford School of Medicine, Stanford, CA, United States of America
| | - Donna M. Bouley
- Department of Comparative Medicine, Stanford School of Medicine, Stanford, CA, United States of America
| | - Philip Kaye
- Department of Histopathology, Nottingham University Hospitals and University of Nottingham NDDC NIHR BRC, Nottingham, United Kingdom
| | - Nigel P. Minton
- Clostridia Research Group, BBSRC/EPSRC Synthetic Biology Research Centre, School of Life Sciences, Centre for Biomolecular Sciences, The University of Nottingham, Nottingham, United kingdom
- NIHR Nottingham Biomedical Research Centre, Nottingham University Hospitals NHS Trust and the University of Nottingham, Nottingham, United Kingdom
| | - Matthew Bogyo
- Department of Pathology, Stanford School of Medicine, Stanford, CA, United States of America
- Department of Microbiology and Immunology, Stanford School of Medicine, Stanford, CA, United States of America
| | - Sarah A. Kuehne
- Oral Microbiology Group, School of Dentistry and Institute of Microbiology and Infection, College of Medical and Dental Sciences, The University of Birmingham, Birmingham, United Kingdom
| | - Roman A. Melnyk
- Department of Biochemistry, University of Toronto, and Program in Molecular Medicine, The Hospital for Sick Children, Toronto, ON, Canada
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Trzilova D, Anjuwon-Foster BR, Torres Rivera D, Tamayo R. Rho factor mediates flagellum and toxin phase variation and impacts virulence in Clostridioides difficile. PLoS Pathog 2020; 16:e1008708. [PMID: 32785266 PMCID: PMC7446863 DOI: 10.1371/journal.ppat.1008708] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2020] [Revised: 08/24/2020] [Accepted: 06/16/2020] [Indexed: 12/17/2022] Open
Abstract
The intestinal pathogen Clostridioides difficile exhibits heterogeneity in motility and toxin production. This phenotypic heterogeneity is achieved through phase variation by site-specific recombination via the DNA recombinase RecV, which reversibly inverts the "flagellar switch" upstream of the flgB operon. A recV mutation prevents flagellar switch inversion and results in phenotypically locked strains. The orientation of the flagellar switch influences expression of the flgB operon post-transcription initiation, but the specific molecular mechanism is unknown. Here, we report the isolation and characterization of spontaneous suppressor mutants in the non-motile, non-toxigenic recV flg OFF background that regained motility and toxin production. The restored phenotypes corresponded with increased expression of flagellum and toxin genes. The motile suppressor mutants contained single-nucleotide polymorphisms (SNPs) in rho, which encodes the bacterial transcription terminator Rho factor. Analyses using transcriptional reporters indicate that Rho contributes to heterogeneity in flagellar gene expression by preferentially terminating transcription of flg OFF mRNA within the 5' leader sequence. Additionally, Rho is important for initial colonization of the intestine in a mouse model of infection, which may in part be due to the sporulation and growth defects observed in the rho mutants. Together these data implicate Rho factor as a regulator of gene expression affecting phase variation of important virulence factors of C. difficile.
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Affiliation(s)
- Dominika Trzilova
- Department of Microbiology and Immunology, University of North Carolina at Chapel Hill School of Medicine, Chapel Hill, North Carolina, United States of America
| | - Brandon R. Anjuwon-Foster
- Department of Microbiology and Immunology, University of North Carolina at Chapel Hill School of Medicine, Chapel Hill, North Carolina, United States of America
| | - Dariana Torres Rivera
- Department of Microbiology and Immunology, University of North Carolina at Chapel Hill School of Medicine, Chapel Hill, North Carolina, United States of America
| | - Rita Tamayo
- Department of Microbiology and Immunology, University of North Carolina at Chapel Hill School of Medicine, Chapel Hill, North Carolina, United States of America
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24
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Romo JA, Markey L, Kumamoto CA. Lipid Species in the GI Tract are Increased by the Commensal Fungus Candida albicans and Decrease the Virulence of Clostridioides difficile. J Fungi (Basel) 2020; 6:E100. [PMID: 32635220 PMCID: PMC7557729 DOI: 10.3390/jof6030100] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2020] [Revised: 06/18/2020] [Accepted: 06/30/2020] [Indexed: 12/12/2022] Open
Abstract
Prior antibiotic treatment is a risk factor for Clostridioides difficile infection (CDI); the commensal gut microbiota plays a key role in determining host susceptibility to the disease. Previous studies demonstrate that the pre-colonization of mice with a commensal fungus, Candida albicans, protects against a lethal challenge with C. difficile spores. The results reported here demonstrate that the cecum contents of antibiotic-treated mice with C. albicans colonization contained different levels of several lipid species, including non-esterified, unsaturated long-chain fatty acids compared to non-C. albicans-colonized mice. Mice fed olive oil for one week and challenged with C. difficile spores showed enhanced survival compared to PBS-fed mice. The amount of olive oil administered was not sufficient to cause weight gain or to result in significant changes to the bacterial microbiota, in contrast to the effects of a high-fat diet. Furthermore, the direct exposure of C. difficile bacteria in laboratory culture to the unsaturated fatty acid oleic acid, the major fatty acid found in olive oil, reduced the transcription of genes encoding the toxins and reduced the survival of bacteria in the post-exponential phase. Therefore, the effects of C. albicans on the metabolite milieu contributed to the attenuation of C. difficile virulence.
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Affiliation(s)
- Jesus A. Romo
- Department of Molecular Biology and Microbiology, Tufts University, Boston, MA 02111, USA
| | - Laura Markey
- Graduate Program in Molecular Microbiology, Graduate School of Biomedical Sciences and Department of Molecular Biology and Microbiology, Tufts University, Boston, MA 02111, USA;
| | - Carol A. Kumamoto
- Department of Molecular Biology and Microbiology, Tufts University, Boston, MA 02111, USA
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25
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Draft Genome Sequence of Clostridium estertheticum-Like Strain FP3, Isolated from Spoiled Uncooked Lamb. Microbiol Resour Announc 2020; 9:9/20/e00434-20. [PMID: 32409559 PMCID: PMC7225558 DOI: 10.1128/mra.00434-20] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/02/2022] Open
Abstract
Clostridium estertheticum-like strain FP3 was isolated from vacuum-packaged refrigerated spoiled lamb. This bacterium is psychrotrophic, Gram positive, spore-forming, and a strict anaerobe. Here, we report the generation and annotation of the 5.6-Mb draft genome sequence of C. estertheticum-like strain FP3. Clostridium estertheticum-like strain FP3 was isolated from vacuum-packaged refrigerated spoiled lamb. This bacterium is psychrotrophic, Gram positive, spore-forming, and a strict anaerobe. Here, we report the generation and annotation of the 5.6-Mb draft genome sequence of C. estertheticum-like strain FP3.
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Whole-Genome Sequencing of Clostridium sp. Strain FP2, Isolated from Spoiled Venison. Microbiol Resour Announc 2020; 9:9/18/e00334-20. [PMID: 32354983 PMCID: PMC7193938 DOI: 10.1128/mra.00334-20] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
Clostridium sp. strain FP2 was isolated from vacuum-packaged refrigerated spoiled venison in New Zealand. This report describes the generation and annotation of the 5.6-Mb draft genome sequence of Clostridium sp. FP2, which will facilitate future functional genomic studies to improve our understanding of premature spoilage of red meats. Clostridium sp. strain FP2 was isolated from vacuum-packaged refrigerated spoiled venison in New Zealand. This report describes the generation and annotation of the 5.6-Mb draft genome sequence of Clostridium sp. FP2, which will facilitate future functional genomic studies to improve our understanding of premature spoilage of red meats.
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Draft Genome Sequence of Clostridium sp. Strain FP1, with Similarity to Clostridium tagluense, Isolated from Spoiled Lamb. Microbiol Resour Announc 2020; 9:9/18/e00321-20. [PMID: 32354982 PMCID: PMC7193937 DOI: 10.1128/mra.00321-20] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022] Open
Abstract
Clostridium sp. strain FP1 was isolated from vacuum-packaged refrigerated spoiled lamb, and this article describes its 5.4-Mb draft genome sequence. The FP1 genome was sequenced to facilitate source tracking and attribution studies, adding to our understanding of the role of Clostridium species in premature spoilage of red meats. Clostridium sp. strain FP1 was isolated from vacuum-packaged refrigerated spoiled lamb, and this article describes its 5.4-Mb draft genome sequence. The FP1 genome was sequenced to facilitate source tracking and attribution studies, adding to our understanding of the role of Clostridium species in premature spoilage of red meats.
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Complete Genome Sequence of Mycoplasma felis Strain Myco-2, Isolated from an Equine Tracheal Wash Sample in Japan. Microbiol Resour Announc 2020; 9:9/9/e00057-20. [PMID: 32107293 PMCID: PMC7046814 DOI: 10.1128/mra.00057-20] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022] Open
Abstract
Mycoplasma felis causes conjunctivitis in cats and respiratory diseases in horses. We report here the complete genome assembly of equine Mycoplasma felis strain Myco-2, which was isolated from an ill horse in Japan. Mycoplasma felis causes conjunctivitis in cats and respiratory diseases in horses. We report here the complete genome assembly of equine Mycoplasma felis strain Myco-2, which was isolated from an ill horse in Japan.
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29
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Flexible Cobamide Metabolism in Clostridioides ( Clostridium) difficile 630 Δ erm. J Bacteriol 2020; 202:JB.00584-19. [PMID: 31685533 DOI: 10.1128/jb.00584-19] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2019] [Accepted: 10/26/2019] [Indexed: 01/05/2023] Open
Abstract
Clostridioides (Clostridium) difficile is an opportunistic pathogen known for its ability to colonize the human gut under conditions of dysbiosis. Several aspects of its carbon and amino acid metabolism have been investigated, but its cobamide (vitamin B12 and related cofactors) metabolism remains largely unexplored. C. difficile has seven predicted cobamide-dependent pathways encoded in its genome in addition to a nearly complete cobamide biosynthesis pathway and a cobamide uptake system. To address the importance of cobamides to C. difficile, we studied C. difficile 630 Δerm and mutant derivatives under cobamide-dependent conditions in vitro Our results show that C. difficile can use a surprisingly diverse array of cobamides for methionine and deoxyribonucleotide synthesis and can use alternative metabolites or enzymes, respectively, to bypass these cobamide-dependent processes. C. difficile 630 Δerm produces the cobamide pseudocobalamin when provided the early precursor 5-aminolevulinic acid or the late intermediate cobinamide (Cbi) and produces other cobamides if provided an alternative lower ligand. The ability of C. difficile 630 Δerm to take up cobamides and Cbi at micromolar or lower concentrations requires the transporter BtuFCD. Genomic analysis revealed genetic variations in the btuFCD loci of different C. difficile strains, which may result in differences in the ability to take up cobamides and Cbi. These results together demonstrate that, like other aspects of its physiology, cobamide metabolism in C. difficile is versatile.IMPORTANCE The ability of the opportunistic pathogen Clostridioides difficile to cause disease is closely linked to its propensity to adapt to conditions created by dysbiosis of the human gut microbiota. The cobamide (vitamin B12) metabolism of C. difficile has been underexplored, although it has seven metabolic pathways that are predicted to require cobamide-dependent enzymes. Here, we show that C. difficile cobamide metabolism is versatile, as it can use a surprisingly wide variety of cobamides and has alternative functions that can bypass some of its cobamide requirements. Furthermore, C. difficile does not synthesize cobamides de novo but produces them when given cobamide precursors. A better understanding of C. difficile cobamide metabolism may lead to new strategies to treat and prevent C. difficile-associated disease.
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Regulation and Anaerobic Function of the Clostridioides difficile β-Lactamase. Antimicrob Agents Chemother 2019; 64:AAC.01496-19. [PMID: 31611350 DOI: 10.1128/aac.01496-19] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2019] [Accepted: 10/07/2019] [Indexed: 01/05/2023] Open
Abstract
Clostridioides difficile causes severe antibiotic-associated diarrhea and colitis. C. difficile is an anaerobic, Gram-positive sporeformer that is highly resistant to β-lactams, the most commonly prescribed antibiotics. The resistance of C. difficile to β-lactam antibiotics allows the pathogen to replicate and cause disease in antibiotic-treated patients. However, the mechanisms of β-lactam resistance in C. difficile are not fully understood. Our data reinforce prior evidence that C. difficile produces a β-lactamase, which is a common β-lactam resistance mechanism found in other bacterial species. Here, we characterize the C. difficile bla operon that encodes a lipoprotein of unknown function and a β-lactamase that was greatly induced in response to several classes of β-lactam antibiotics. An in-frame deletion of the operon abolished β-lactamase activity in C. difficile strain 630Δerm and resulted in decreased resistance to the β-lactam ampicillin. We found that the activity of this β-lactamase, BlaCDD, is dependent upon the redox state of the enzyme. In addition, we observed that transport of BlaCDD out of the cytosol and to the cell surface is facilitated by an N-terminal signal sequence. Our data demonstrate that a cotranscribed lipoprotein, BlaX, aids in BlaCDD activity. Further, we identified a conserved BlaRI regulatory system and demonstrated via insertional disruption that BlaRI controls transcription of the blaXCDD genes in response to β-lactams. These results provide support for the function of a β-lactamase in C. difficile antibiotic resistance and reveal the unique roles of a coregulated lipoprotein and reducing environment in C. difficile β-lactamase activity.
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Complete Genome Sequence of Mycobacterium avium subsp. hominissuis Strain JP-H-1, Isolated from an Equine Abortion Case in Japan. Microbiol Resour Announc 2019; 8:8/48/e01228-19. [PMID: 31776220 PMCID: PMC6883107 DOI: 10.1128/mra.01228-19] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Here, we describe the complete genome assembly of Mycobacterium avium subsp. hominissuis strain JP-H-1, collected from an equine abortion case in Japan. JP-H-1 has a 5,491,452-bp circular chromosome and 3 plasmids. Here, we describe the complete genome assembly of Mycobacterium avium subsp. hominissuis strain JP-H-1, collected from an equine abortion case in Japan. JP-H-1 has a 5,491,452-bp circular chromosome and 3 plasmids.
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32
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Draft Genome Sequence of Clostridium estertheticum subsp. laramiense DSM 14864 T, Isolated from Spoiled Uncooked Beef. Microbiol Resour Announc 2019; 8:8/47/e01275-19. [PMID: 31753947 PMCID: PMC6872889 DOI: 10.1128/mra.01275-19] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
Clostridium estertheticum subsp. laramiense type strain DSM 14864 (ATCC 51254) was isolated from vacuum-packaged refrigerated spoiled beef. This report describes the generation and annotation of the 5.0-Mb draft genome sequence of C. estertheticum subsp. laramiense DSM 14864T.
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33
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Chen KY, Rathod J, Chiu YC, Chen JW, Tsai PJ, Huang IH. The Transcriptional Regulator Lrp Contributes to Toxin Expression, Sporulation, and Swimming Motility in Clostridium difficile. Front Cell Infect Microbiol 2019; 9:356. [PMID: 31681632 PMCID: PMC6811523 DOI: 10.3389/fcimb.2019.00356] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2019] [Accepted: 10/02/2019] [Indexed: 12/17/2022] Open
Abstract
Clostridium difficile is a Gram-positive, spore-forming bacterium, and major cause of nosocomial diarrhea. Related studies have identified numerous factors that influence virulence traits such as the production of the two primary toxins, toxin A (TcdA) and toxin B (TcdB), as well as sporulation, motility, and biofilm formation. However, multiple putative transcriptional regulators are reportedly encoded in the genome, and additional factors are likely involved in virulence regulation. Although the leucine-responsive regulatory protein (Lrp) has been studied extensively in Gram-negative bacteria, little is known about its function in Gram-positive bacteria, although homologs have been identified in the genome. This study revealed that disruption of the lone lrp homolog in C. difficile decelerated growth under nutrient-limiting conditions, increased TcdA and TcdB production. Lrp was also found to negatively regulate sporulation while positively regulate swimming motility in strain R20291, but not in strain 630. The C. difficile Lrp appeared to function through transcriptional repression or activation. In addition, the lrp mutant was relatively virulent in a mouse model of infection. The results of this study collectively demonstrated that Lrp has broad regulatory function in C. difficile toxin expression, sporulation, motility, and pathogenesis.
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Affiliation(s)
- Kuan-Yu Chen
- Department of Microbiology and Immunology, College of Medicine, National Cheng Kung University, Tainan, Taiwan
| | - Jagat Rathod
- Department of Earth Sciences, National Cheng Kung University, Tainan, Taiwan
| | - Yi-Ching Chiu
- Department of Microbiology and Immunology, College of Medicine, National Cheng Kung University, Tainan, Taiwan
| | - Jenn-Wei Chen
- Department of Microbiology and Immunology, College of Medicine, National Cheng Kung University, Tainan, Taiwan.,Center of Infectious Disease and Signaling Research, National Cheng Kung University, Tainan, Taiwan
| | - Pei-Jane Tsai
- Center of Infectious Disease and Signaling Research, National Cheng Kung University, Tainan, Taiwan.,Department of Medical Laboratory Science and Biotechnology, College of Medicine, National Cheng Kung University, Tainan, Taiwan
| | - I-Hsiu Huang
- Department of Microbiology and Immunology, College of Medicine, National Cheng Kung University, Tainan, Taiwan.,Center of Infectious Disease and Signaling Research, National Cheng Kung University, Tainan, Taiwan
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Bouillaut L, Newton W, Sonenshein AL, Belitsky BR. DdlR, an essential transcriptional regulator of peptidoglycan biosynthesis in Clostridioides difficile. Mol Microbiol 2019; 112:1453-1470. [PMID: 31483905 DOI: 10.1111/mmi.14371] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/13/2019] [Indexed: 12/11/2022]
Abstract
D-Ala-D-Ala ligase, encoded by ddl genes, is responsible for the synthesis of a dipeptide, D-Ala-D-Ala, an essential precursor of bacterial peptidoglycan. In Clostridioides difficile, the single ddl gene is located upstream of the ddlR gene, which encodes a putative transcriptional regulator. Using mutational and transcriptional analysis and DNA-binding assays, DdlR was found to be a direct activator of the ddl ddlR operon. DdlR is a member of the MocR/GabR-type proteins that have aminotransferase-like, pyridoxal 5'-phosphate-binding domains. A DdlR mutation that prevented covalent binding of pyridoxal 5'-phosphate abolished the ability of DdlR to activate transcription. Addition of D-Ala-D-Ala to the medium inactivated DdlR, reducing dipeptide biosynthesis. In contrast, D-Ala-D-Ala limitation caused a dramatic increase in expression from the ddl promoter. Though uncommon for transcription regulators, C. difficile DdlR is essential, as the ddlR null mutant cells could not grow even in complex laboratory media in the absence of D-Ala-D-Ala. A dyad symmetry sequence, which is located immediately upstream of the -35 region of the ddl promoter, serves as an important element of the DdlR-binding site. This sequence is conserved upstream of putative DdlR targets in other bacteria of classes Clostridia and Bacilli, indicating a similar mode of regulation of these genes.
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Affiliation(s)
- Laurent Bouillaut
- Department of Molecular Biology and Microbiology, Tufts University School of Medicine, Boston, MA, 02111, USA
| | - William Newton
- Department of Molecular Biology and Microbiology, Tufts University School of Medicine, Boston, MA, 02111, USA
| | - Abraham L Sonenshein
- Department of Molecular Biology and Microbiology, Tufts University School of Medicine, Boston, MA, 02111, USA
| | - Boris R Belitsky
- Department of Molecular Biology and Microbiology, Tufts University School of Medicine, Boston, MA, 02111, USA
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35
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Shoaei P, Shojaei H, Jalali M, Khorvash F, Hosseini SM, Ataei B, Vakili B, Ebrahimi F, Tavakoli H, Esfandiari Z, Weese JS. Clostridium difficile isolated from faecal samples in patients with ulcerative colitis. BMC Infect Dis 2019; 19:361. [PMID: 31039738 PMCID: PMC6492486 DOI: 10.1186/s12879-019-3965-8] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2018] [Accepted: 04/08/2019] [Indexed: 12/18/2022] Open
Abstract
BACKGROUND Ulcerative colitis (UC) is an inflammatory bowel disease (IBD) that is widely identified worldwide. This study aimed to investigate the phenotypic characterization and molecular typing of Clostridium difficile isolates among patients with UC at an inflammatory bowel disease clinic in Iran. METHODS In this cross-sectional study, conducted from April 2015 to December 2015, 85 UC patients were assessed for C.difficile infection (CDI). C. difficile isolates were characterized based on their toxin profile and antimicrobial resistance pattern. Multi-locus sequence typing analysis (MLST) and PCR ribotyping were performed to define the genetic relationships between different lineages of toxigenic strains. RESULTS The prevalence of C. difficile isolates was 31.8% (27/85) in patients, of those 15 patients (17.6%) had CDI. Three different sequence types (STs) identified based on MLST among the toxigenic isolates, that is ST54 (33.3%), ST2 (53.3%), and ST37 (13.6%). C. difficile strains were divided into four different PCR-ribotypes (012, 014, 017 and IR1). The most common ribotype was 014 accounting for 48.3% (7/15) of all strains. The strains isolated during the first episode and recurrence of CDI usually belonged to PCR ribotype 014 (ST2). A high rate of CDI recurrence (14.1%, 12/85) experienced in UC patients. Colonization of the gastrointestinal tract with non-toxigenic C. difficile strains was frequent among patients with mild disease. All C. difficile isolates were susceptible to metronidazole, and vancomycin, 86 and 67% of isolates were resistant to clindamycin and erythromycin respectively. There was no correlation between the toxin type and antibiotic resistance (p > 0.05). CONCLUSION Overall CDI is rather prevalent in UC patients. All patients with CDI experienced moderate to severe disease and exposed to different antimicrobial and anti-inflammatory agents. Close monitoring and appropriate management including early detection and fast treatment of CDI will improve UC outcomes.
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Affiliation(s)
- Parisa Shoaei
- Nosocomial Infection Research Center, Isfahan University of Medical Sciences, Isfahan, Iran
| | - Hasan Shojaei
- Department of Microbiology, School of Medicine, Isfahan University of Medical Sciences, Isfahan, Iran
| | - Mohammad Jalali
- School of Food Science and Nutrition, Isfahan University of Medical Sciences, Isfahan, Iran
| | - Farzin Khorvash
- Nosocomial Infection Research Center, Isfahan University of Medical Sciences, Isfahan, Iran.
| | - Sayed Mohsen Hosseini
- Epidemiology and biostatics department, Isfahan University of Medical sciences, Isfahan, Iran
| | - Behrooz Ataei
- Infectious Diseases and Tropical Medicine Research Center, Isfahan University of Medical Sciences, Isfahan, Iran
| | - Bahareh Vakili
- Department of Microbiology, Science and Research Branch, Islamic Azad University, Tehran, Iran
| | - Fatemeh Ebrahimi
- Department of Microbiology, Islamic Azad University of Falavarjan, Isfahan, Iran
| | - Hossein Tavakoli
- Department of Physiology and Pathophysiology, University of Manitoba, Winnipeg, MB, Canada
| | - Zahra Esfandiari
- Department of Research and Development, Vice Chancellory for food and drug, Isfahan, Iran
| | - J Scott Weese
- Department of Pathobiology and Centre for Public Health and Zoonoses, Ontario Veterinary College, University of Guelph, Guelph, Canada
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36
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Shrestha R, Cochran AM, Sorg JA. The requirement for co-germinants during Clostridium difficile spore germination is influenced by mutations in yabG and cspA. PLoS Pathog 2019; 15:e1007681. [PMID: 30943268 PMCID: PMC6464247 DOI: 10.1371/journal.ppat.1007681] [Citation(s) in RCA: 30] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2018] [Revised: 04/15/2019] [Accepted: 03/05/2019] [Indexed: 12/13/2022] Open
Abstract
Clostridium difficile spore germination is critical for the transmission of disease. C. difficile spores germinate in response to cholic acid derivatives, such as taurocholate (TA), and amino acids, such as glycine or alanine. Although the receptor with which bile acids are recognized (germinant receptor) is known, the amino acid co-germinant receptor has remained elusive. Here, we used EMS mutagenesis to generate mutants with altered requirements for the amino acid co-germinant, similar to the strategy we used previously to identify the bile acid germinant receptor, CspC. Surprisingly, we identified strains that do not require co-germinants, and the mutant spores germinated in response to TA alone. Upon sequencing these mutants, we identified different mutations in yabG. In C. difficile, yabG expression is required for the processing of key germination components to their mature forms (e.g., CspBA to CspB and CspA). A defined yabG mutant exacerbated the EMS mutant phenotype. Building upon this work, we found that small deletions in cspA resulted in spores that germinated in the presence of TA alone without the requirement of a co-germinant. cspA encodes a pseudoprotease that was previously shown to be important for incorporation of the CspC germinant receptor. Herein, our study builds upon the role of CspA during C. difficile spore germination by providing evidence that CspA is important for recognition of co-germinants during C. difficile spore germination. Our work suggests that two pseudoproteases (CspC and CspA) likely function as the C. difficile germinant receptors. Germination by C. difficile spores is one of the very first steps in the pathogenesis of this organism. The transition from the metabolically dormant spore form to the actively-growing, toxin-producing vegetative form is initiated by certain host-derived bile acids and amino acid signals. Despite near universal conservation in endospore-forming bacteria of the Ger-type germinant receptors, C. difficile and related organisms do not encode these proteins. In prior work, we identified the C. difficile bile acid germinant receptor as the CspC pseudoprotease. In this manuscript, we implicate the CspA pseudoprotease as the C. difficile co-germinant receptor. C. difficile cspA is encoded as a translational fusion to cspB. The resulting CspBA protein is processed post-translationally by the YabG protease. Inactivation of yabG resulted in strains whose spores no longer responded to amino acids or divalent cations as co-germinants and germinated in response to bile acid alone. Building upon this, we found that small deletions in the cspA portion of cspBA resulted in spores that could germinate in response to bile acids alone. Our results suggest that two pseudoproteases regulate C. difficile spore germination and provide further evidence that C. difficile spore germination proceeds through a novel spore germination pathway.
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Affiliation(s)
- Ritu Shrestha
- Department of Biology, Texas A&M University, College Station, United States of America
| | - Alicia M. Cochran
- Department of Biology, Texas A&M University, College Station, United States of America
| | - Joseph A. Sorg
- Department of Biology, Texas A&M University, College Station, United States of America
- * E-mail:
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Bouillaut L, Dubois T, Francis MB, Daou N, Monot M, Sorg JA, Sonenshein AL, Dupuy B. Role of the global regulator Rex in control of NAD + -regeneration in Clostridioides (Clostridium) difficile. Mol Microbiol 2019; 111:1671-1688. [PMID: 30882947 DOI: 10.1111/mmi.14245] [Citation(s) in RCA: 27] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/13/2019] [Indexed: 12/31/2022]
Abstract
For the human pathogen Clostridioides (also known as Clostridium) difficile, the ability to adapt to nutrient availability is critical for its proliferation and production of toxins during infection. Synthesis of the toxins is regulated by the availability of certain carbon sources, fermentation products and amino acids (e.g. proline, cysteine, isoleucine, leucine and valine). The effect of proline is attributable at least in part to its role as an inducer and substrate of D-proline reductase (PR), a Stickland reaction that regenerates NAD+ from NADH. Many Clostridium spp. use Stickland metabolism (co-fermentation of pairs of amino acids) to generate ATP and NAD+ . Synthesis of PR is activated by PrdR, a proline-responsive regulatory protein. Here we report that PrdR, in the presence of proline, represses other NAD+ -generating pathways, such as the glycine reductase and succinate-acetyl CoA utilization pathways leading to butyrate production, but does so indirectly by affecting the activity of Rex, a global redox-sensing regulator that responds to the NAD+ /NADH ratio. Our results indicate that PR activity is the favored mechanism for NAD+ regeneration and that both Rex and PrdR influence toxin production. Using the hamster model of C. difficile infection, we revealed the importance of PrdR-regulated Stickland metabolism in the virulence of C. difficile.
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Affiliation(s)
- Laurent Bouillaut
- Department of Molecular Biology and Microbiology, Tufts University School of Medicine, Boston, MA, 02111
| | - Thomas Dubois
- Pathogenesis of Bacterial Anaerobes Laboratory, Institut Pasteur, 75724, Paris, France.,Université Paris Diderot, Sorbonne Paris Cité, Paris, France
| | - Michael B Francis
- Department of Biology, Texas A&M University, College Station, TX, 77843
| | - Nadine Daou
- Department of Molecular Biology and Microbiology, Tufts University School of Medicine, Boston, MA, 02111
| | - Marc Monot
- Pathogenesis of Bacterial Anaerobes Laboratory, Institut Pasteur, 75724, Paris, France.,Université Paris Diderot, Sorbonne Paris Cité, Paris, France
| | - Joseph A Sorg
- Department of Biology, Texas A&M University, College Station, TX, 77843
| | - Abraham L Sonenshein
- Department of Molecular Biology and Microbiology, Tufts University School of Medicine, Boston, MA, 02111
| | - Bruno Dupuy
- Pathogenesis of Bacterial Anaerobes Laboratory, Institut Pasteur, 75724, Paris, France.,Université Paris Diderot, Sorbonne Paris Cité, Paris, France
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Daou N, Wang Y, Levdikov VM, Nandakumar M, Livny J, Bouillaut L, Blagova E, Zhang K, Belitsky BR, Rhee K, Wilkinson AJ, Sun X, Sonenshein AL. Impact of CodY protein on metabolism, sporulation and virulence in Clostridioides difficile ribotype 027. PLoS One 2019; 14:e0206896. [PMID: 30699117 PMCID: PMC6353076 DOI: 10.1371/journal.pone.0206896] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2017] [Accepted: 09/25/2018] [Indexed: 12/16/2022] Open
Abstract
Toxin synthesis and endospore formation are two of the most critical factors that determine the outcome of infection by Clostridioides difficile. The two major toxins, TcdA and TcdB, are the principal factors causing damage to the host. Spores are the infectious form of C. difficile, permit survival of the bacterium during antibiotic treatment and are the predominant cell form that leads to recurrent infection. Toxin production and sporulation have their own specific mechanisms of regulation, but they share negative regulation by the global regulatory protein CodY. Determining the extent of such regulation and its detailed mechanism is important for understanding the linkage between two apparently independent biological phenomena and raises the possibility of creating new ways of limiting infection. The work described here shows that a codY null mutant of a hypervirulent (ribotype 027) strain is even more virulent than its parent in a mouse model of infection and that the mutant expresses most sporulation genes prematurely during exponential growth phase. Moreover, examining the expression patterns of mutants producing CodY proteins with different levels of residual activity revealed that expression of the toxin genes is dependent on total CodY inactivation, whereas most sporulation genes are turned on when CodY activity is only partially diminished. These results suggest that, in wild-type cells undergoing nutrient limitation, sporulation genes can be turned on before the toxin genes.
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Affiliation(s)
- Nadine Daou
- Department of Molecular Biology and Microbiology, Tufts University School of Medicine, Boston, MA, United States of America
| | - Yuanguo Wang
- Department of Infectious Disease and Global Health, Cummings School of Veterinary Medicine, Tufts University, North Grafton, MA, United States of America
| | - Vladimir M. Levdikov
- Structural Biology Laboratory, Department of Chemistry, University of York, York, United Kingdom
| | - Madhumitha Nandakumar
- Department of Medicine, Division of Infectious Diseases, Weill Cornell Medical College, New York, NY, United States of America
| | - Jonathan Livny
- Broad Institute of MIT and Harvard, Cambridge, MA, United States of America
| | - Laurent Bouillaut
- Department of Molecular Biology and Microbiology, Tufts University School of Medicine, Boston, MA, United States of America
| | - Elena Blagova
- Structural Biology Laboratory, Department of Chemistry, University of York, York, United Kingdom
| | - Keshan Zhang
- Department of Infectious Disease and Global Health, Cummings School of Veterinary Medicine, Tufts University, North Grafton, MA, United States of America
| | - Boris R. Belitsky
- Department of Molecular Biology and Microbiology, Tufts University School of Medicine, Boston, MA, United States of America
| | - Kyu Rhee
- Department of Medicine, Division of Infectious Diseases, Weill Cornell Medical College, New York, NY, United States of America
| | - Anthony J. Wilkinson
- Structural Biology Laboratory, Department of Chemistry, University of York, York, United Kingdom
| | - Xingmin Sun
- Department of Molecular Medicine, Morsani College of Medicine, University of South Florida, Tampa, FL, United States of America
| | - Abraham L. Sonenshein
- Department of Molecular Biology and Microbiology, Tufts University School of Medicine, Boston, MA, United States of America
- * E-mail:
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Oral Immunization with Nontoxigenic Clostridium difficile Strains Expressing Chimeric Fragments of TcdA and TcdB Elicits Protective Immunity against C. difficile Infection in Both Mice and Hamsters. Infect Immun 2018; 86:IAI.00489-18. [PMID: 30150259 DOI: 10.1128/iai.00489-18] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2018] [Accepted: 08/21/2018] [Indexed: 12/29/2022] Open
Abstract
The symptoms of Clostridium difficile infection (CDI) are attributed largely to two C. difficile toxins, TcdA and TcdB. Significant efforts have been devoted to developing vaccines targeting both toxins through parenteral immunization routes. However, C. difficile is an enteric pathogen, and mucosal/oral immunization would be particularly useful to protect the host against CDI, considering that the gut is the main site of disease onset and progression. Moreover, vaccines directed only against toxins do not target the cells and spores that transmit the disease. Previously, we constructed a chimeric vaccine candidate, mTcd138, comprised of the glucosyltransferase and cysteine proteinase domains of TcdB and the receptor binding domain of TcdA. In this study, to develop an oral vaccine that can target both C. difficile toxins and colonization/adhesion factors, we expressed mTcd138 in a nontoxigenic C. difficile (NTCD) strain, resulting in strain NTCD_mTcd138. Oral immunization with spores of NTCD_mTcd138 provided mice full protection against infection with a hypervirulent C. difficile strain, UK6 (ribotype 027). The protective strength and efficacy of NTCD_mTcd138 were further evaluated in the acute CDI hamster model. Oral immunization with spores of NTCD_mTcd138 also provided hamsters significant protection against infection with 2 × 104 UK6 spores, a dose 200-fold higher than the lethal dose of UK6 in hamsters. These results imply that the genetically modified, nontoxigenic C. difficile strain expressing mTcd138 may represent a novel mucosal vaccine candidate against CDI.
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Cyclic Diguanylate Regulates Virulence Factor Genes via Multiple Riboswitches in Clostridium difficile. mSphere 2018; 3:3/5/e00423-18. [PMID: 30355665 PMCID: PMC6200980 DOI: 10.1128/msphere.00423-18] [Citation(s) in RCA: 30] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
In Clostridium difficile, the signaling molecule c-di-GMP regulates multiple processes affecting its ability to cause disease, including swimming and surface motility, biofilm formation, toxin production, and intestinal colonization. In this study, we used RNA-seq to define the transcriptional regulon of c-di-GMP in C. difficile. Many new targets of c-di-GMP regulation were identified, including multiple putative colonization factors. Transcriptional analyses revealed a prominent role for riboswitches in c-di-GMP signaling. Only a subset of the 16 previously predicted c-di-GMP riboswitches were functional in vivo and displayed potential variability in their response kinetics to c-di-GMP. This work underscores the importance of studying c-di-GMP riboswitches in a relevant biological context and highlights the role of the riboswitches in controlling gene expression in C. difficile. The intracellular signaling molecule cyclic diguanylate (c-di-GMP) regulates many processes in bacteria, with a central role in controlling the switch between motile and nonmotile lifestyles. Recent work has shown that in Clostridium difficile (also called Clostridioides difficile), c-di-GMP regulates swimming and surface motility, biofilm formation, toxin production, and intestinal colonization. In this study, we determined the transcriptional regulon of c-di-GMP in C. difficile, employing overexpression of a diguanylate cyclase gene to artificially manipulate intracellular c-di-GMP. Consistent with prior work, c-di-GMP regulated the expression of genes involved in swimming and surface motility. c-di-GMP also affected the expression of multiple genes encoding cell envelope proteins, several of which affected biofilm formation in vitro. A substantial proportion of the c-di-GMP regulon appears to be controlled either directly or indirectly via riboswitches. We confirmed the functionality of 11 c-di-GMP riboswitches, demonstrating their effects on downstream gene expression independent of the upstream promoters. The class I riboswitches uniformly functioned as “off” switches in response to c-di-GMP, while class II riboswitches acted as “on” switches. Transcriptional analyses of genes 3′ of c-di-GMP riboswitches over a broad range of c-di-GMP levels showed that relatively modest changes in c-di-GMP levels are capable of altering gene transcription, with concomitant effects on microbial behavior. This work expands the known c-di-GMP signaling network in C. difficile and emphasizes the role of the riboswitches in controlling known and putative virulence factors in C. difficile. IMPORTANCE In Clostridium difficile, the signaling molecule c-di-GMP regulates multiple processes affecting its ability to cause disease, including swimming and surface motility, biofilm formation, toxin production, and intestinal colonization. In this study, we used RNA-seq to define the transcriptional regulon of c-di-GMP in C. difficile. Many new targets of c-di-GMP regulation were identified, including multiple putative colonization factors. Transcriptional analyses revealed a prominent role for riboswitches in c-di-GMP signaling. Only a subset of the 16 previously predicted c-di-GMP riboswitches were functional in vivo and displayed potential variability in their response kinetics to c-di-GMP. This work underscores the importance of studying c-di-GMP riboswitches in a relevant biological context and highlights the role of the riboswitches in controlling gene expression in C. difficile.
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Woods EC, Edwards AN, Childress KO, Jones JB, McBride SM. The C. difficile clnRAB operon initiates adaptations to the host environment in response to LL-37. PLoS Pathog 2018; 14:e1007153. [PMID: 30125334 PMCID: PMC6117091 DOI: 10.1371/journal.ppat.1007153] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2018] [Revised: 08/30/2018] [Accepted: 07/16/2018] [Indexed: 01/05/2023] Open
Abstract
To cause disease, Clostridioides (Clostridium) difficile must resist killing by innate immune effectors in the intestine, including the host antimicrobial peptide, cathelicidin (LL-37). The mechanisms that enable C. difficile to adapt to the intestine in the presence of antimicrobial peptides are unknown. Expression analyses revealed an operon, CD630_16170-CD630_16190 (clnRAB), which is highly induced by LL-37 and is not expressed in response to other cell-surface active antimicrobials. This operon encodes a predicted transcriptional regulator (ClnR) and an ABC transporter system (ClnAB), all of which are required for function. Analyses of a clnR mutant indicate that ClnR is a pleiotropic regulator that directly binds to LL-37 and controls expression of numerous genes, including many involved in metabolism, cellular transport, signaling, gene regulation, and pathogenesis. The data suggest that ClnRAB is a novel regulatory mechanism that senses LL-37 as a host signal and regulates gene expression to adapt to the host intestinal environment during infection.
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Affiliation(s)
- Emily C. Woods
- Department of Microbiology and Immunology, and Emory University Antibiotic Resistance Center, Emory University School of Medicine, Atlanta, GA, United States of America
| | - Adrianne N. Edwards
- Department of Microbiology and Immunology, and Emory University Antibiotic Resistance Center, Emory University School of Medicine, Atlanta, GA, United States of America
| | - Kevin O. Childress
- Department of Microbiology and Immunology, and Emory University Antibiotic Resistance Center, Emory University School of Medicine, Atlanta, GA, United States of America
| | - Joshua B. Jones
- Department of Microbiology and Immunology, and Emory University Antibiotic Resistance Center, Emory University School of Medicine, Atlanta, GA, United States of America
| | - Shonna M. McBride
- Department of Microbiology and Immunology, and Emory University Antibiotic Resistance Center, Emory University School of Medicine, Atlanta, GA, United States of America
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Characterization of Flagellum and Toxin Phase Variation in Clostridioides difficile Ribotype 012 Isolates. J Bacteriol 2018; 200:JB.00056-18. [PMID: 29735765 DOI: 10.1128/jb.00056-18] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2018] [Accepted: 05/02/2018] [Indexed: 12/21/2022] Open
Abstract
Clostridioides difficile causes diarrheal diseases mediated in part by the secreted toxins TcdA and TcdB. C. difficile produces flagella that also contribute to motility and bacterial adherence to intestinal cells during infection. Flagellum expression and toxin gene expression are linked via the flagellar alternative sigma factor, SigD. Recently, we identified a flagellar switch upstream of the early flagellar biosynthesis operon that mediates phase variation of both flagellum and toxin production in C. difficile strain R20291. However, we were unable to detect flagellar switch inversion in C. difficile strain 630, a ribotype 012 strain commonly used in research labs, suggesting that the strain is phase locked. To determine whether a phase-locked flagellar switch is limited to 630 or present more broadly in ribotype 012 strains, we assessed the frequency and phenotypic outcomes of flagellar switch inversion in multiple C. difficile ribotype 012 isolates. The laboratory-adapted strain JIR8094, a derivative of strain 630, and six clinical and environmental isolates were all found to be phase-off, nonmotile, and attenuated for toxin production. We isolated low-frequency motile derivatives of JIR8094 with partial recovery of motility and toxin production and found that additional changes in JIR8094 impact these processes. The clinical and environmental isolates varied considerably in the frequency by which flagellar phase-on derivatives arose, and these derivatives showed fully restored motility and toxin production. Taken together, these results demonstrate heterogeneity in flagellar and toxin phase variation among C. difficile ribotype 012 strains and perhaps other ribotypes, which could impact disease progression and diagnosis.IMPORTANCEC. difficile produces flagella that enhance bacterial motility and secretes toxins that promote diarrheal disease symptoms. Previously, we found that production of flagella and toxins is coregulated via a flippable DNA element termed the flagellar switch, which mediates the phase-variable production of these factors. Here, we evaluate multiple isolates of C. difficile ribotype 012 strains and find them to be primarily flagellar phase off (flg-off state). Some, but not all, of these isolates showed the ability to switch between flg-on and -off states. These findings suggest heterogeneity in the ability of C. difficile ribotype 012 strains to phase-vary flagellum and toxin production, which may broadly apply to pathogenic C. difficile.
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Woods EC, Wetzel D, Mukerjee M, McBride SM. Examination of the Clostridioides (Clostridium) difficile VanZ ortholog, CD1240. Anaerobe 2018; 53:108-115. [PMID: 29940245 DOI: 10.1016/j.anaerobe.2018.06.013] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2018] [Revised: 06/20/2018] [Accepted: 06/21/2018] [Indexed: 02/08/2023]
Abstract
Clostridioides (Clostridium) difficile causes severe diarrheal disease that is directly associated with antibiotic use and resistance. Although C. difficile demonstrates intrinsic resistance to many antimicrobials, few genetic mechanisms of resistance have been characterized in this pathogen. In this study, we investigated the putative resistance factor, CD1240 (VanZ1), an ortholog of the teicoplanin resistance factor, VanZ, of Enterococcus faecium. In C. difficile, the vanZ1 gene is located within the skin element of the sporulation factor σK, which is excised from the mother cell compartment during sporulation. This unique localization enabled us to create a vanZ1 deletion mutant by inducing excision of the skin element. The Δskin mutant exhibited moderately decreased resistance to teicoplanin and had small effects on growth in some other cell-surface antimicrobials tested. Examination of vanZ1 expression revealed induction of vanZ1 transcription by the antimicrobial peptide LL-37; however, LL-37 resistance was not impacted by VanZ1, and none of the other tested antimicrobials induced vanZ1 expression. Further, expression of vanZ1 via an inducible promoter in the Δskin mutant restored growth in teicoplanin. These results demonstrate that like the E. faecium VanZ, C. difficile VanZ1 contributes to low-level teicoplanin resistance through an undefined mechanism.
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Affiliation(s)
- Emily C Woods
- Department of Microbiology and Immunology, Emory University School of Medicine, Emory Antibiotic Resistance Center, Atlanta, GA, USA
| | - Daniela Wetzel
- Department of Microbiology and Immunology, Emory University School of Medicine, Emory Antibiotic Resistance Center, Atlanta, GA, USA
| | - Monjori Mukerjee
- Department of Microbiology and Immunology, Emory University School of Medicine, Emory Antibiotic Resistance Center, Atlanta, GA, USA
| | - Shonna M McBride
- Department of Microbiology and Immunology, Emory University School of Medicine, Emory Antibiotic Resistance Center, Atlanta, GA, USA.
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Nawrocki KL, Wetzel D, Jones JB, Woods EC, McBride SM. Ethanolamine is a valuable nutrient source that impacts Clostridium difficile pathogenesis. Environ Microbiol 2018; 20:1419-1435. [PMID: 29349925 PMCID: PMC5903940 DOI: 10.1111/1462-2920.14048] [Citation(s) in RCA: 42] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2017] [Revised: 01/03/2018] [Accepted: 01/14/2018] [Indexed: 12/12/2022]
Abstract
Clostridium (Clostridioides) difficile is a gastrointestinal pathogen that colonizes the intestinal tract of mammals and can cause severe diarrheal disease. Although C. difficile growth is confined to the intestinal tract, our understanding of the specific metabolites and host factors that are important for the growth of the bacterium is limited. In other enteric pathogens, the membrane-derived metabolite, ethanolamine (EA), is utilized as a nutrient source and can function as a signal to initiate the production of virulence factors. In this study, we investigated the effects of ethanolamine and the role of the predicted ethanolamine gene cluster (CD1907-CD1925) on C. difficile growth. Using targeted mutagenesis, we disrupted genes within the eut cluster and assessed their roles in ethanolamine utilization, and the impact of eut disruption on the outcome of infection in a hamster model of disease. Our results indicate that the eut gene cluster is required for the growth of C. difficile on ethanolamine as a primary nutrient source. Further, the inability to utilize ethanolamine resulted in greater virulence and a shorter time to morbidity in the animal model. Overall, these data suggest that ethanolamine is an important nutrient source within the host and that, in contrast to other intestinal pathogens, the metabolism of ethanolamine by C. difficile can delay the onset of disease.
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Affiliation(s)
- Kathryn L. Nawrocki
- Department of Microbiology and Immunology, and Emory Antibiotic Resistance Center, Emory University School of Medicine, Atlanta, GA, USA
| | - Daniela Wetzel
- Department of Microbiology and Immunology, and Emory Antibiotic Resistance Center, Emory University School of Medicine, Atlanta, GA, USA
| | - Joshua B. Jones
- Department of Microbiology and Immunology, and Emory Antibiotic Resistance Center, Emory University School of Medicine, Atlanta, GA, USA
| | - Emily C. Woods
- Department of Microbiology and Immunology, and Emory Antibiotic Resistance Center, Emory University School of Medicine, Atlanta, GA, USA
| | - Shonna M. McBride
- Department of Microbiology and Immunology, and Emory Antibiotic Resistance Center, Emory University School of Medicine, Atlanta, GA, USA
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McAllister KN, Bouillaut L, Kahn JN, Self WT, Sorg JA. Using CRISPR-Cas9-mediated genome editing to generate C. difficile mutants defective in selenoproteins synthesis. Sci Rep 2017; 7:14672. [PMID: 29116155 PMCID: PMC5677094 DOI: 10.1038/s41598-017-15236-5] [Citation(s) in RCA: 70] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2017] [Accepted: 10/24/2017] [Indexed: 12/16/2022] Open
Abstract
Clostridium difficile is a significant concern as a nosocomial pathogen, and genetic tools are important when analyzing the physiology of such organisms so that the underlying physiology/pathogenesis of the organisms can be studied. Here, we used TargeTron to investigate the role of selenoproteins in C. difficile Stickland metabolism and found that a TargeTron insertion into selD, encoding the selenophosphate synthetase that is essential for the specific incorporation of selenium into selenoproteins, results in a significant growth defect and a global loss of selenium incorporation. However, because of potential polar effects of the TargeTron insertion, we developed a CRISPR-Cas9 mutagenesis system for C. difficile. This system rapidly and efficiently introduces site-specific mutations into the C. difficile genome (20-50% mutation frequency). The selD CRISPR deletion mutant had a growth defect in protein-rich medium and mimicked the phenotype of a generated TargeTron selD mutation. Our findings suggest that Stickland metabolism could be a target for future antibiotic therapies and that the CRISPR-Cas9 system can introduce rapid and efficient modifications into the C. difficile genome.
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Affiliation(s)
| | - Laurent Bouillaut
- Department of Molecular Biology & Microbiology, Tufts University School of Medicine, Boston, MA, USA
- Matrivax R&D Corp. 650 Albany Street, Boston, MA, USA
| | - Jennifer N Kahn
- Department of Biology, Texas A&M University, College Station, TX, USA
| | - William T Self
- Burnett School of Biomedical Sciences, University of Central Florida, Orlando, FL, USA
| | - Joseph A Sorg
- Department of Biology, Texas A&M University, College Station, TX, USA.
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The Phosphotransfer Protein CD1492 Represses Sporulation Initiation in Clostridium difficile. Infect Immun 2016; 84:3434-3444. [PMID: 27647869 DOI: 10.1128/iai.00735-16] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2016] [Accepted: 09/12/2016] [Indexed: 12/18/2022] Open
Abstract
The formation of spores is critical for the survival of Clostridium difficile outside the host gastrointestinal tract. Persistence of C. difficile spores greatly contributes to the spread of C. difficile infection (CDI), and the resistance of spores to antimicrobials facilitates the relapse of infection. Despite the importance of sporulation to C. difficile pathogenesis, the molecular mechanisms controlling spore formation are not well understood. The initiation of sporulation is known to be regulated through activation of the conserved transcription factor Spo0A. Multiple regulators influence Spo0A activation in other species; however, many of these factors are not conserved in C. difficile and few novel factors have been identified. Here, we investigated the function of a protein, CD1492, that is annotated as a kinase and was originally proposed to promote sporulation by directly phosphorylating Spo0A. We found that deletion of CD1492 resulted in increased sporulation, indicating that CD1492 is a negative regulator of sporulation. Accordingly, we observed increased transcription of Spo0A-dependent genes in the CD1492 mutant. Deletion of CD1492 also resulted in decreased toxin production in vitro and in decreased virulence in the hamster model of CDI. Further, the CD1492 mutant demonstrated effects on gene expression that are not associated with Spo0A activation, including lower sigD and rstA transcription, suggesting that this protein interacts with factors other than Spo0A. Altogether, the data indicate that CD1492 negatively affects sporulation and positively influences motility and virulence. These results provide further evidence that C. difficile sporulation is regulated differently from that of other endospore-forming species.
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Yu Z, Gunn L, Brennan E, Reid R, Wall PG, Gaora PÓ, Hurley D, Bolton D, Fanning S. Complete Genome Sequence of Clostridium estertheticum DSM 8809, a Microbe Identified in Spoiled Vacuum Packed Beef. Front Microbiol 2016; 7:1764. [PMID: 27891116 PMCID: PMC5104964 DOI: 10.3389/fmicb.2016.01764] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2016] [Accepted: 10/20/2016] [Indexed: 11/13/2022] Open
Abstract
Blown pack spoilage (BPS) is a major issue for the beef industry. Etiological agents of BPS involve members of a group of Clostridium species, including Clostridium estertheticum which has the ability to produce gas, mostly carbon dioxide, under anaerobic psychotrophic growth conditions. This spore-forming bacterium grows slowly under laboratory conditions, and it can take up to 3 months to produce a workable culture. These characteristics have limited the study of this commercially challenging bacterium. Consequently information on this bacterium is limited and no effective controls are currently available to confidently detect and manage this production risk. In this study the complete genome of C. estertheticum DSM 8809 was determined by SMRT® sequencing. The genome consists of a circular chromosome of 4.7 Mbp along with a single plasmid carrying a potential tellurite resistance gene tehB and a Tn3-like resolvase-encoding gene tnpR. The genome sequence was searched for central metabolic pathways that would support its biochemical profile and several enzymes contributing to this phenotype were identified. Several putative antibiotic/biocide/metal resistance-encoding genes and virulence factors were also identified in the genome, a feature that requires further research. The availability of the genome sequence will provide a basic blueprint from which to develop valuable biomarkers that could support and improve the detection and control of this bacterium along the beef production chain.
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Affiliation(s)
- Zhongyi Yu
- UCD-Centre for Food Safety, School of Public Health, Physiotherapy and Sports Science, School of Biomedical and Biomolecular Science, University College Dublin Dublin, Ireland
| | - Lynda Gunn
- UCD-Centre for Food Safety, School of Public Health, Physiotherapy and Sports Science, School of Biomedical and Biomolecular Science, University College Dublin Dublin, Ireland
| | - Evan Brennan
- UCD-Centre for Food Safety, School of Public Health, Physiotherapy and Sports Science, School of Biomedical and Biomolecular Science, University College Dublin Dublin, Ireland
| | | | - Patrick G Wall
- UCD-Centre for Food Safety, School of Public Health, Physiotherapy and Sports Science, School of Biomedical and Biomolecular Science, University College Dublin Dublin, Ireland
| | - Peadar Ó Gaora
- UCD-Centre for Food Safety, School of Public Health, Physiotherapy and Sports Science, School of Biomedical and Biomolecular Science, University College Dublin Dublin, Ireland
| | - Daniel Hurley
- UCD-Centre for Food Safety, School of Public Health, Physiotherapy and Sports Science, School of Biomedical and Biomolecular Science, University College Dublin Dublin, Ireland
| | | | - Séamus Fanning
- UCD-Centre for Food Safety, School of Public Health, Physiotherapy and Sports Science, School of Biomedical and Biomolecular Science, University College Dublin Dublin, Ireland
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Edwards AN, Karim ST, Pascual RA, Jowhar LM, Anderson SE, McBride SM. Chemical and Stress Resistances of Clostridium difficile Spores and Vegetative Cells. Front Microbiol 2016; 7:1698. [PMID: 27833595 PMCID: PMC5080291 DOI: 10.3389/fmicb.2016.01698] [Citation(s) in RCA: 77] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2016] [Accepted: 10/12/2016] [Indexed: 12/11/2022] Open
Abstract
Clostridium difficile is a Gram-positive, sporogenic and anaerobic bacterium that causes a potentially fatal colitis. C. difficile enters the body as dormant spores that germinate in the colon to form vegetative cells that secrete toxins and cause the symptoms of infection. During transit through the intestine, some vegetative cells transform into spores, which are more resistant to killing by environmental insults than the vegetative cells. Understanding the inherent resistance properties of the vegetative and spore forms of C. difficile is imperative for the development of methods to target and destroy the bacterium. The objective of this study was to define the chemical and environmental resistance properties of C. difficile vegetative cells and spores. We examined vegetative cell and spore tolerances of three C. difficile strains, including 630Δerm, a 012 ribotype and a derivative of a past epidemic strain; R20291, a 027 ribotype and current epidemic strain; and 5325, a clinical isolate that is a 078 ribotype. All isolates were tested for tolerance to ethanol, oxygen, hydrogen peroxide, butanol, chloroform, heat and sodium hypochlorite (household bleach). Our results indicate that 630Δerm vegetative cells (630 spo0A) are more resistant to oxidative stress than those of R20291 (R20291 spo0A) and 5325 (5325 spo0A). In addition, 5325 spo0A vegetative cells exhibited greater resistance to organic solvents. In contrast, 630Δerm spores were more sensitive than R20291 or 5325 spores to butanol. Spores from all three strains exhibited high levels of resistance to ethanol, hydrogen peroxide, chloroform and heat, although R20291 spores were more resistant to temperatures in the range of 60-75°C. Finally, household bleach served as the only chemical reagent tested that consistently reduced C. difficile vegetative cells and spores of all tested strains. These findings establish conditions that result in vegetative cell and spore elimination and illustrate the resistance of C. difficile to common decontamination methods. These results further demonstrate that the vegetative cells and spores of various C. difficile strains have different resistance properties that may impact decontamination of surfaces and hands.
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Affiliation(s)
- Adrianne N Edwards
- Emory Antibiotic Resistance Center, Department of Microbiology and Immunology, Emory University School of Medicine, Atlanta GA, USA
| | - Samiha T Karim
- Emory Antibiotic Resistance Center, Department of Microbiology and Immunology, Emory University School of Medicine, Atlanta GA, USA
| | - Ricardo A Pascual
- Emory Antibiotic Resistance Center, Department of Microbiology and Immunology, Emory University School of Medicine, Atlanta GA, USA
| | - Lina M Jowhar
- Emory Antibiotic Resistance Center, Department of Microbiology and Immunology, Emory University School of Medicine, Atlanta GA, USA
| | - Sarah E Anderson
- Emory Antibiotic Resistance Center, Department of Microbiology and Immunology, Emory University School of Medicine, Atlanta GA, USA
| | - Shonna M McBride
- Emory Antibiotic Resistance Center, Department of Microbiology and Immunology, Emory University School of Medicine, Atlanta GA, USA
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CodY-Dependent Regulation of Sporulation in Clostridium difficile. J Bacteriol 2016; 198:2113-30. [PMID: 27246573 DOI: 10.1128/jb.00220-16] [Citation(s) in RCA: 55] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2016] [Accepted: 05/22/2016] [Indexed: 01/05/2023] Open
Abstract
UNLABELLED Clostridium difficile must form a spore to survive outside the gastrointestinal tract. The factors that trigger sporulation in C. difficile remain poorly understood. Previous studies have suggested that a link exists between nutritional status and sporulation initiation in C. difficile In this study, we investigated the impact of the global nutritional regulator CodY on sporulation in C. difficile strains from the historical 012 ribotype and the current epidemic 027 ribotype. Sporulation frequencies were increased in both backgrounds, demonstrating that CodY represses sporulation in C. difficile The 027 codY mutant exhibited a greater increase in spore formation than the 012 codY mutant. To determine the role of CodY in the observed sporulation phenotypes, we examined several factors that are known to influence sporulation in C. difficile Using transcriptional reporter fusions and quantitative reverse transcription-PCR (qRT-PCR) analysis, we found that two loci associated with the initiation of sporulation, opp and sinR, are regulated by CodY. The data demonstrate that CodY is a repressor of sporulation in C. difficile and that the impact of CodY on sporulation and expression of specific genes is significantly influenced by the strain background. These results suggest that the variability of CodY-dependent regulation is an important contributor to virulence and sporulation in current epidemic isolates. This report provides further evidence that nutritional state, virulence, and sporulation are linked in C. difficile IMPORTANCE This study sought to examine the relationship between nutrition and sporulation in C. difficile by examining the global nutritional regulator CodY. CodY is a known virulence and nutritional regulator of C. difficile, but its role in sporulation was unknown. Here, we demonstrate that CodY is a negative regulator of sporulation in two different ribotypes of C. difficile We also demonstrate that CodY regulates known effectors of sporulation, Opp and SinR. These results support the idea that nutrient limitation is a trigger for sporulation in C. difficile and that the response to nutrient limitation is coordinated by CodY. Additionally, we demonstrate that CodY has an altered role in sporulation regulation for some strains.
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The Clostridium difficile Dlt Pathway Is Controlled by the Extracytoplasmic Function Sigma Factor σV in Response to Lysozyme. Infect Immun 2016; 84:1902-1916. [PMID: 27068095 DOI: 10.1128/iai.00207-16] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2016] [Accepted: 04/06/2016] [Indexed: 12/18/2022] Open
Abstract
Clostridium difficile (also known as Peptoclostridium difficile) is a major nosocomial pathogen and a leading cause of antibiotic-associated diarrhea throughout the world. Colonization of the intestinal tract is necessary for C. difficile to cause disease. Host-produced antimicrobial proteins (AMPs), such as lysozyme, are present in the intestinal tract and can deter colonization by many bacterial pathogens, and yet C. difficile is able to survive in the colon in the presence of these AMPs. Our prior studies established that the Dlt pathway, which increases the surface charge of the bacterium by addition of d-alanine to teichoic acids, is important for C. difficile resistance to a variety of AMPs. We sought to determine what genetic mechanisms regulate expression of the Dlt pathway. In this study, we show that a dlt null mutant is severely attenuated for growth in lysozyme and that expression of the dltDABC operon is induced in response to lysozyme. Moreover, we found that a mutant lacking the extracytoplasmic function (ECF) sigma factor σ(V) does not induce dlt expression in response to lysozyme, indicating that σ(V) is required for regulation of lysozyme-dependent d-alanylation of the cell wall. Using reporter gene fusions and 5' RACE (rapid amplification of cDNA ends) analysis, we identified promoter elements necessary for lysozyme-dependent and lysozyme-independent dlt expression. In addition, we observed that both a sigV mutant and a dlt mutant are more virulent in a hamster model of infection. These findings demonstrate that cell wall d-alanylation in C. difficile is induced by lysozyme in a σ(V)-dependent manner and that this pathway impacts virulence in vivo.
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