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Ouyang Z, Zhao M, Li J, Zhang Y, Zhao J. Cyclic diguanylate differentially regulates the expression of virulence factors and pathogenesis-related phenotypes in Clostridioides difficile. Microbiol Res 2024; 286:127811. [PMID: 38909416 DOI: 10.1016/j.micres.2024.127811] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2024] [Revised: 06/03/2024] [Accepted: 06/12/2024] [Indexed: 06/25/2024]
Abstract
Clostridioides difficile infection (CDI) caused by toxigenic C. difficile is the leading cause of antimicrobial and healthcare-associated diarrhea. The pathogenicity of C. difficile relies on the synergistic effect of multiple virulence factors, including spores, flagella, type IV pili (T4P), toxins, and biofilm. Spores enable survival and transmission of C. difficile, while adhesion factors such as flagella and T4P allow C. difficile to colonize and persist in the host intestine. Subsequently, C. difficile produces the toxins TcdA and TcdB, causing pseudomembranous colitis and other C. difficile-associated diseases; adhesion factors bind to the extracellular matrix to form biofilm, allowing C. difficile to evade drug and immune system attack and cause recurrent infection. Cyclic diguanylate (c-di-GMP) is a near-ubiquitous second messenger that extensively regulates morphology, the expression of virulence factors, and multiple physiological processes in C. difficile. In this review, we summarize current knowledge of how c-di-GMP differentially regulates the expression of virulence factors and pathogenesis-related phenotypes in C. difficile. We highlight that C. difficile spore formation and expression of toxin and flagella genes are inhibited at high intracellular levels of c-di-GMP, while T4P biosynthesis, cell aggregation, and biofilm formation are induced. Recent studies have enhanced our understanding of the c-di-GMP signaling networks in C. difficile and provided insights for the development of c-di-GMP-dependent strategies against CDI.
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Affiliation(s)
- Zirou Ouyang
- Hebei Provincial Center for Clinical Laboratories, The Second Hospital of Hebei Medical University, Shijiazhuang, Hebei, China
| | - Min Zhao
- Hebei Provincial Center for Clinical Laboratories, The Second Hospital of Hebei Medical University, Shijiazhuang, Hebei, China
| | - Jiayiren Li
- Hebei Provincial Center for Clinical Laboratories, The Second Hospital of Hebei Medical University, Shijiazhuang, Hebei, China
| | - Yulian Zhang
- Hebei Provincial Center for Clinical Laboratories, The Second Hospital of Hebei Medical University, Shijiazhuang, Hebei, China
| | - Jianhong Zhao
- Hebei Provincial Center for Clinical Laboratories, The Second Hospital of Hebei Medical University, Shijiazhuang, Hebei, China.
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2
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DiCandia MA, Edwards AN, Alcaraz YB, Monteiro MP, Lee CD, Vargas Cuebas G, Bagchi P, McBride SM. A conserved switch controls virulence, sporulation, and motility in C. difficile. PLoS Pathog 2024; 20:e1012224. [PMID: 38739653 PMCID: PMC11115286 DOI: 10.1371/journal.ppat.1012224] [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: 10/09/2023] [Revised: 05/23/2024] [Accepted: 04/25/2024] [Indexed: 05/16/2024] Open
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, 3D structural analyses of Spo0E revealed specific and exclusive interactions between Spo0E and binding partners in C. difficile and B. subtilis that provide insight into the conservation of this regulatory mechanism among different species.
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Affiliation(s)
- Michael A. DiCandia
- Department of Microbiology and Immunology, Emory University School of Medicine, Emory Antibiotic Resistance Center, Atlanta, Georgia, United States of America
| | - Adrianne N. Edwards
- Department of Microbiology and Immunology, Emory University School of Medicine, Emory Antibiotic Resistance Center, Atlanta, Georgia, United States of America
| | - Ysabella B. Alcaraz
- Department of Microbiology and Immunology, Emory University School of Medicine, Emory Antibiotic Resistance Center, Atlanta, Georgia, United States of America
| | - Marcos P. Monteiro
- Department of Microbiology and Immunology, Emory University School of Medicine, Emory Antibiotic Resistance Center, Atlanta, Georgia, United States of America
| | - Cheyenne D. Lee
- Department of Microbiology and Immunology, Emory University School of Medicine, Emory Antibiotic Resistance Center, Atlanta, Georgia, United States of America
| | - Germán Vargas Cuebas
- Department of Microbiology and Immunology, Emory University School of Medicine, Emory Antibiotic Resistance Center, Atlanta, Georgia, United States of America
| | - Pritha Bagchi
- Emory Integrated Proteomics Core, Emory University, Atlanta, Georgia, United States of America
| | - Shonna M. McBride
- Department of Microbiology and Immunology, Emory University School of Medicine, Emory Antibiotic Resistance Center, Atlanta, Georgia, United States of America
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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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4
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Gong JJ, Huang IH, Su MSW, Xie SX, Liu WY, Huang CR, Hung YP, Wu SR, Tsai PJ, Ko WC, Chen JW. Phage transcriptional regulator X (PtrX)-mediated augmentation of toxin production and virulence in Clostridioides difficile strain R20291. Microbiol Res 2024; 280:127576. [PMID: 38183754 DOI: 10.1016/j.micres.2023.127576] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2023] [Revised: 11/24/2023] [Accepted: 12/13/2023] [Indexed: 01/08/2024]
Abstract
Clostridioides difficile is a Gram-positive, anaerobic, and spore-forming bacterial member of the human gut microbiome. The primary virulence factors of C. difficile are toxin A and toxin B. These toxins damage the cell cytoskeleton and cause various diseases, from diarrhea to severe pseudomembranous colitis. Evidence suggests that bacteriophages can regulate the expression of the pathogenicity locus (PaLoc) genes of C. difficile. We previously demonstrated that the genome of the C. difficile RT027 strain NCKUH-21 contains a prophage-like DNA sequence, which was found to be markedly similar to that of the φCD38-2 phage. In the present study, we investigated the mechanisms underlying the φNCKUH-21-mediated regulation of the pathogenicity and the PaLoc genes expression in the lysogenized C. difficile strain R20291. The carriage of φNCKUH-21 in R20291 cells substantially enhanced toxin production, bacterial motility, biofilm formation, and spore germination in vitro. Subsequent mouse studies revealed that the lysogenized R20291 strain caused a more severe infection than the wild-type strain. We screened three φNCKUH-21 genes encoding DNA-binding proteins to check their effects on PaLoc genes expression. The overexpression of NCKUH-21_03890, annotated as a transcriptional regulator (phage transcriptional regulator X, PtrX), considerably enhanced toxin production, biofilm formation, and bacterial motility of R20291. Transcriptome analysis further confirmed that the overexpression of ptrX led to the upregulation of the expression of toxin genes, flagellar genes, and csrA. In the ptrX-overexpressing R20291 strain, PtrX influenced the expression of flagellar genes and the sigma factor gene sigD, possibly through an increased flagellar phase ON configuration ratio.
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Affiliation(s)
- Jun-Jia Gong
- Institute of Basic Medical Sciences, College of Medicine, National Cheng Kung University, Tainan, Taiwan
| | - I-Hsiu Huang
- Department of Biochemistry and Microbiology, Oklahoma State University Center for Health Sciences, Tulsa, OK 74107, USA
| | - Marcia Shu-Wei Su
- Department of Biotechnology and Laboratory Science in Medicine, National Yang Ming Chiao Tung University, Taipei, Taiwan
| | - Si-Xuan Xie
- Department of Microbiology and Immunology, College of Medicine, National Cheng Kung University, Tainan, Taiwan
| | - Wei-Yong Liu
- Department of Microbiology and Immunology, College of Medicine, National Cheng Kung University, Tainan, Taiwan
| | - Cheng-Rung Huang
- Institute of Basic Medical Sciences, College of Medicine, National Cheng Kung University, Tainan, Taiwan
| | - Yuan-Pin Hung
- Department of Microbiology and Immunology, College of Medicine, National Cheng Kung University, Tainan, Taiwan; Department of Internal Medicine, National Cheng Kung University Hospital, College of Medicine, National Cheng Kung University, Tainan, Taiwan; Department of Medicine, College of Medicine, National Cheng Kung University, Tainan, Taiwan
| | - Shang-Rung Wu
- Institute of Basic Medical Sciences, College of Medicine, National Cheng Kung University, Tainan, Taiwan; Institute of Oral Medicine, National Cheng Kung University, Tainan, Taiwan
| | - Pei-Jane Tsai
- Institute of Basic Medical Sciences, College of Medicine, National Cheng Kung University, Tainan, Taiwan; Department of Medical Laboratory Science and Biotechnology, National Cheng Kung University, Tainan, Taiwan; Department of Pathology, National Cheng Kung University Hospital, Tainan, Taiwan; Center for Clinical Medicine Research, National Cheng Kung University Hospital, Tainan, Taiwan
| | - Wen-Chien Ko
- Department of Internal Medicine, National Cheng Kung University Hospital, College of Medicine, National Cheng Kung University, Tainan, Taiwan; Department of Medicine, College of Medicine, National Cheng Kung University, Tainan, Taiwan
| | - Jenn-Wei Chen
- Institute of Basic Medical Sciences, College of Medicine, National Cheng Kung University, Tainan, Taiwan; Department of Microbiology and Immunology, College of Medicine, National Cheng Kung University, Tainan, Taiwan.
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5
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Zeng J, Fang S, Guo J, Dong M, Tian G, Tao L. Fight or flee, a vital choice for Clostridioides difficile. MLIFE 2024; 3:14-20. [PMID: 38827507 PMCID: PMC11139204 DOI: 10.1002/mlf2.12102] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 07/10/2023] [Revised: 09/17/2023] [Accepted: 10/08/2023] [Indexed: 06/04/2024]
Abstract
Clostridioides difficile is a leading cause of healthcare-associated infections, causing billions of economic losses every year. Its symptoms range from mild diarrhea to life-threatening damage to the colon. Transmission and recurrence of C. difficile infection (CDI) are mediated by the metabolically dormant spores, while the virulence of C. difficile is mainly due to the two large clostridial toxins, TcdA and TcdB. Producing toxins or forming spores are two different strategies for C. difficile to cope with harsh environmental conditions. It is of great significance to understand the molecular mechanisms for C. difficile to skew to either of the cellular processes. Here, we summarize the current understanding of the regulation and connections between toxin production and sporulation in C. difficile and further discuss the potential solutions for yet-to-be-answered questions.
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Affiliation(s)
- Ji Zeng
- School of Biomedical and Pharmaceutical SciencesGuangdong University of TechnologyGuangzhouChina
| | - Shuying Fang
- School of Biomedical and Pharmaceutical SciencesGuangdong University of TechnologyGuangzhouChina
| | - Jinquan Guo
- Department of Brest SurgeryPanyu Central HospitalGuangzhouChina
| | - Min Dong
- Department of MicrobiologyHarvard Medical SchoolBostonMassachusettsUSA
- Department of Urology, Boston Children's HospitalHarvard Medical SchoolBostonMassachusettsUSA
| | - Guo‐Bao Tian
- Department of MicrobiologyZhongshan School of Medicine, Sun Yat‐sen UniversityGuangzhouChina
- Advanced Medical Technology Center, The First Affiliated Hospital, Zhongshan School of MedicineSun Yat‐sen UniversityGuangzhouChina
- Key Laboratory of Tropical Diseases Control (Sun Yat‐sen University), Ministry of EducationGuangzhouChina
- School of MedicineXizang Minzu UniversityXianyangChina
| | - Liang Tao
- Center for Infectious Disease Research, Westlake Laboratory of Life Sciences and BiomedicineWestlake UniversityHangzhouChina
- Research Center for Industries of the Future, School of Life SciencesWestlake UniversityHangzhouChina
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Marvaud JC, Bouttier S, Saunier J, Kansau I. Clostridioides difficile Flagella. Int J Mol Sci 2024; 25:2202. [PMID: 38396876 PMCID: PMC10889297 DOI: 10.3390/ijms25042202] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2024] [Revised: 02/04/2024] [Accepted: 02/09/2024] [Indexed: 02/25/2024] Open
Abstract
Clostridioides difficile is an important pathogen for humans with a lead in nosocomial infection, but it is also more and more common in communities. Our knowledge of the pathology has historically been focused on the toxins produced by the bacteria that remain its major virulence factors. But the dysbiosis of the intestinal microbiota creating the conditions for the colonization appears to be fundamental for our understanding of the disease. Colonization implies several steps for the bacteria that do or do not use their capacity of motility with the synthesis of flagella. In this review, we focus on the current understanding of different topics on the C. difficile flagellum, ranging from its genetic organization to the vaccinal interest in it.
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Affiliation(s)
- Jean-Christophe Marvaud
- Institut MICALIS, INRAE, AgroParisTech, Equipe Bactéries Pathogènes et Santé, Faculté de Pharmacie, Université Paris-Saclay, 91400 Orsay, France (I.K.)
| | - Sylvie Bouttier
- Institut MICALIS, INRAE, AgroParisTech, Equipe Bactéries Pathogènes et Santé, Faculté de Pharmacie, Université Paris-Saclay, 91400 Orsay, France (I.K.)
| | - Johanna Saunier
- Matériaux et Santé, Faculté de pharmacie, Université Paris Saclay, 91400 Orsay, France
| | - Imad Kansau
- Institut MICALIS, INRAE, AgroParisTech, Equipe Bactéries Pathogènes et Santé, Faculté de Pharmacie, Université Paris-Saclay, 91400 Orsay, France (I.K.)
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Frost LR, Stark R, Anonye BO, MacCreath TO, Ferreira LRP, Unnikrishnan M. Dual RNA-seq identifies genes and pathways modulated during Clostridioides difficile colonization. mSystems 2023; 8:e0055523. [PMID: 37615437 PMCID: PMC10654110 DOI: 10.1128/msystems.00555-23] [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: 05/31/2023] [Accepted: 07/11/2023] [Indexed: 08/25/2023] Open
Abstract
IMPORTANCE The initial interactions between the colonic epithelium and the bacterium are likely critical in the establishment of Clostridioides difficile infection, one of the major causes of hospital-acquired diarrhea worldwide. Molecular interactions between C. difficile and human gut cells have not been well defined mainly due to the technical challenges of studying cellular host-pathogen interactions with this anaerobe. Here we have examined transcriptional changes occurring in the pathogen and host cells during the initial 24 hours of infection. Our data indicate several changes in metabolic pathways and virulence-associated factors during the initial bacterium-host cell contact and early stages of infection. We describe canonical pathways enriched based on the expression profiles of a dual RNA sequencing in the host and bacterium, and functions of bacterial factors that are modulated during infection. This study thus provides fresh insight into the early C. difficile infection process.
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Affiliation(s)
- Lucy R. Frost
- Division of Biomedical Sciences, Warwick Medical School, University of Warwick, Coventry, United Kingdom
| | - Richard Stark
- Bioinformatics Research Technology Platform, University of Warwick, Coventry, United Kingdom
| | - Blessing O. Anonye
- Division of Biomedical Sciences, Warwick Medical School, University of Warwick, Coventry, United Kingdom
| | - Thomas O. MacCreath
- Division of Biomedical Sciences, Warwick Medical School, University of Warwick, Coventry, United Kingdom
- School of Life Sciences, University of Warwick, Coventry, United Kingdom
| | - Ludmila R. P. Ferreira
- RNA Systems Biology Laboratory (RSBL), Department of Morphology, Institute of Biological Sciences, Federal University of Minas Gerais, Belo Horizonte, Minas Gerais, Brazil
| | - Meera Unnikrishnan
- Division of Biomedical Sciences, Warwick Medical School, University of Warwick, Coventry, United Kingdom
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Baldassare MA, Bhattacharjee D, Coles JD, Nelson S, McCollum CA, Seekatz AM. Butyrate enhances Clostridioides difficile sporulation in vitro. J Bacteriol 2023; 205:e0013823. [PMID: 37655912 PMCID: PMC10521354 DOI: 10.1128/jb.00138-23] [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: 04/24/2023] [Accepted: 07/11/2023] [Indexed: 09/02/2023] Open
Abstract
Short-chain fatty acids (SCFAs) are products of bacterial fermentation that help maintain important gut functions such as maintenance of the intestinal barrier, cell signaling, and immune homeostasis. The main SCFAs acetate, propionate, and butyrate have demonstrated beneficial effects for the host, including its importance in alleviating infections caused by pathogens such as Clostridioides difficile. Despite the potential role of SCFAs in mitigating C. difficile infection, their direct effect on C. difficile remains unclear. Through a set of in vitro experiments, we investigated how SCFAs influence C. difficile growth, sporulation, and toxin production. Similar to previous studies, we observed that butyrate decreased growth of C. difficile strain 630 in a dose-dependent manner. The presence of butyrate also increased C. difficile sporulation, with minimal increases in toxin production. RNA-Seq analysis validated our experimental results, demonstrating increased expression of sporulation-related genes in conjunction with changes in metabolic and regulatory genes, such as a putative carbon starvation protein, CstA. Collectively, these data suggest that butyrate may induce alternative C. difficile survival pathways, modifying its growth ability and virulence to persist in the gut environment. IMPORTANCE Several studies suggest that butyrate may modulate gut infections, such as reducing inflammation caused by the healthcare-associated Clostridioides difficile. While studies in both animal models and human studies correlate high levels of butyrate with reduced C. difficile burden, the direct impact of butyrate on C. difficile remains unclear. Our study demonstrates that butyrate directly influences C. difficile by increasing its sporulation and modifying its metabolism, potentially using butyrate as a biomarker to shift survival strategies in a changing gut environment. These data point to additional therapeutic approaches to combat C. difficile in a butyrate-directed manner.
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Affiliation(s)
| | - Disha Bhattacharjee
- Department of Biological Sciences, Clemson University, Clemson, South Carolina, USA
| | - Julian D. Coles
- Department of Biological Sciences, Clemson University, Clemson, South Carolina, USA
| | - Sydney Nelson
- Department of Biological Sciences, Clemson University, Clemson, South Carolina, USA
| | - C. Alexis McCollum
- Department of Biological Sciences, Clemson University, Clemson, South Carolina, USA
| | - Anna M. Seekatz
- Department of Biological Sciences, Clemson University, Clemson, South Carolina, USA
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Dicks LMT. Biofilm Formation of Clostridioides difficile, Toxin Production and Alternatives to Conventional Antibiotics in the Treatment of CDI. Microorganisms 2023; 11:2161. [PMID: 37764005 PMCID: PMC10534356 DOI: 10.3390/microorganisms11092161] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2023] [Revised: 08/16/2023] [Accepted: 08/24/2023] [Indexed: 09/29/2023] Open
Abstract
Clostridioides difficile is considered a nosocomial pathogen that flares up in patients exposed to antibiotic treatment. However, four out of ten patients diagnosed with C. difficile infection (CDI) acquired the infection from non-hospitalized individuals, many of whom have not been treated with antibiotics. Treatment of recurrent CDI (rCDI) with antibiotics, especially vancomycin (VAN) and metronidazole (MNZ), increases the risk of experiencing a relapse by as much as 70%. Fidaxomicin, on the other hand, proved more effective than VAN and MNZ by preventing the initial transcription of RNA toxin genes. Alternative forms of treatment include quorum quenching (QQ) that blocks toxin synthesis, binding of small anion molecules such as tolevamer to toxins, monoclonal antibodies, such as bezlotoxumab and actoxumab, bacteriophage therapy, probiotics, and fecal microbial transplants (FMTs). This review summarizes factors that affect the colonization of C. difficile and the pathogenicity of toxins TcdA and TcdB. The different approaches experimented with in the destruction of C. difficile and treatment of CDI are evaluated.
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Affiliation(s)
- Leon M T Dicks
- Department of Microbiology, Stellenbosch University, Stellenbosch 7600, South Africa
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Wang Y, Jin Y, Sun F, Zhang Y, Liu Q, Wang Q, Yang D, Zhang Y. The c-di-GMP signalling component YfiR regulates multiple bacterial phenotypes and virulence in Pseudomonas plecoglossicida. J Appl Microbiol 2023; 134:lxad157. [PMID: 37500265 DOI: 10.1093/jambio/lxad157] [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: 03/14/2023] [Revised: 07/12/2023] [Accepted: 07/26/2023] [Indexed: 07/29/2023]
Abstract
AIMS Pseudomonas plecoglossicida (P. plecoglossicida) is the causative agent of visceral granulomas disease in large yellow croaker (Larimichthys crocea) and it causes severe economic loss to its industry. Biofilm formation, related to intracellular cyclic bis (3'-5') diguanylic acid (c-di-GMP) levels, is essential for the lifestyle of P. plecoglossicida. This research aims to investigate the role of YfiR-a key regulator of the diguanylate cyclase YfiN to regulate c-di-GMP levels and reveal its regulatory function of bacterial virulence expression in P. plecoglossicida. METHODS AND RESULTS A genetic analysis was carried out to identify the yfiBNR operon for c-di-GMP regulation in P. plecoglossicida. Then, we constructed a yfiR mutant and observed increased c-di-GMP levels, enhanced biofilm formation, increased exopolysaccharides, and diminished swimming and swarming motility in this strain. Moreover, through establishing a yolk sac microinjection infection model in zebrafish larvae, an attenuated phenotype of yfiR mutant that manifested as restored survival and lower bacterial colonization was found. CONCLUSIONS YfiR is the key regulator of virulence in P. plecoglossicida, which contributes to c-di-GMP level, biofilm formation, exopolysaccharides production, swimming, swarming motility, and bacterial colonization in zebrafish model.
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Affiliation(s)
- Ying Wang
- State Key Laboratory of Bioreactor Engineering, Laboratory for Aquatic Animal Diseases, East China University of Science and Technology, Shanghai 200237, China
| | - Yinhua Jin
- State Key Laboratory of Bioreactor Engineering, Laboratory for Aquatic Animal Diseases, East China University of Science and Technology, Shanghai 200237, China
| | - Fei Sun
- State Key Laboratory of Bioreactor Engineering, Laboratory for Aquatic Animal Diseases, East China University of Science and Technology, Shanghai 200237, China
| | - Yuanxing Zhang
- Southern Marine Science and Engineering Guangdong Laboratory (Zhuhai), Zhuhai 519000, China
- Shanghai Engineering Research Center of Maricultured Animal Vaccines, Shanghai 200237, China
| | - Qin Liu
- State Key Laboratory of Bioreactor Engineering, Laboratory for Aquatic Animal Diseases, East China University of Science and Technology, Shanghai 200237, China
- Southern Marine Science and Engineering Guangdong Laboratory (Zhuhai), Zhuhai 519000, China
- Shanghai Engineering Research Center of Maricultured Animal Vaccines, Shanghai 200237, China
| | - Qiyao Wang
- State Key Laboratory of Bioreactor Engineering, Laboratory for Aquatic Animal Diseases, East China University of Science and Technology, Shanghai 200237, China
- Shanghai Engineering Research Center of Maricultured Animal Vaccines, Shanghai 200237, China
| | - Dahai Yang
- State Key Laboratory of Bioreactor Engineering, Laboratory for Aquatic Animal Diseases, East China University of Science and Technology, Shanghai 200237, China
- Shanghai Engineering Research Center of Maricultured Animal Vaccines, Shanghai 200237, China
| | - Yibei Zhang
- State Key Laboratory of Bioreactor Engineering, Laboratory for Aquatic Animal Diseases, East China University of Science and Technology, Shanghai 200237, China
- Shanghai Engineering Research Center of Maricultured Animal Vaccines, Shanghai 200237, China
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11
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Dupuy B. Regulation of Clostridial Toxin Gene Expression: A Pasteurian Tradition. Toxins (Basel) 2023; 15:413. [PMID: 37505682 PMCID: PMC10467148 DOI: 10.3390/toxins15070413] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2023] [Revised: 06/13/2023] [Accepted: 06/19/2023] [Indexed: 07/29/2023] Open
Abstract
The alarming symptoms attributed to several potent clostridial toxins enabled the early identification of the causative agent of tetanus, botulism, and gas gangrene diseases, which belongs to the most famous species of pathogenic clostridia. Although Clostridioides difficile was identified early in the 20th century as producing important toxins, it was identified only 40 years later as the causative agent of important nosocomial diseases upon the advent of antibiotic therapies in hospital settings. Today, C. difficile is a leading public health issue, as it is the major cause of antibiotic-associated diarrhea in adults. In particular, severe symptoms within the spectrum of C. difficile infections are directly related to the levels of toxins produced in the host. This highlights the importance of understanding the regulation of toxin synthesis in the pathogenicity process of C. difficile, whose regulatory factors in response to the gut environment were first identified at the Institut Pasteur. Subsequently, the work of other groups in the field contributed to further deciphering the complex mechanisms controlling toxin production triggered by the intestinal dysbiosis states during infection. This review summarizes the Pasteurian contribution to clostridial toxin regulation studies.
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Affiliation(s)
- Bruno Dupuy
- Institut Pasteur, Université Paris-Cité, UMR-CNRS 6047, Laboratoire Pathogenèse des Bactéries Anaérobies, F-75015 Paris, France
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Chandra H, Sorg JA, Hassett DJ, Sun X. Regulatory transcription factors of Clostridioides difficile pathogenesis with a focus on toxin regulation. Crit Rev Microbiol 2023; 49:334-349. [PMID: 35389761 DOI: 10.1080/1040841x.2022.2054307] [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: 05/11/2021] [Revised: 02/26/2022] [Accepted: 03/14/2022] [Indexed: 11/03/2022]
Abstract
Clostridioides difficile (CD), a nosocomial gut pathogen, produces two major exotoxins, TcdA and TcdB, which disrupt the gut epithelial barrier and induce inflammatory/immune responses, leading to symptoms ranging from mild diarrhoea to pseudomembranous colitis and potentially to death. The expression of toxins is regulated by various transcription factors (TFs) which are induced in response to CD physiological life stages, nutritional availability, and host environment. This review summarises our current understanding on the regulation of toxin expression by TFs that interconnect with pathways of flagellar synthesis, quorum sensing, motility, biofilm formation, sporulation, and phase variation. The pleiotropic roles of some key TFs suggest that toxin production is tightly linked to other cellular processes of the CD physiology.
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Affiliation(s)
- Harish Chandra
- Department of Environmental Microbiology, School of Environmental and Earth Sciences, Babasaheb Bhimrao Ambedkar University, Lucknow, India
- Department of Molecular Genetics, Biochemistry and Microbiology, University of Cincinnati College of Medicine, Cincinnati, OH, USA
| | - Joseph A Sorg
- Department of Biology, Texas A&M University, College Station, TX, USA
| | - Daniel J Hassett
- Department of Molecular Genetics, Biochemistry and Microbiology, University of Cincinnati College of Medicine, Cincinnati, OH, USA
| | - Xingmin Sun
- Department of Molecular Medicine, Morsani College of Medicine, University of South Florida, Tampa, FL, USA
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Baldassare MA, Bhattacharjee D, Coles JD, Nelson S, McCollum CA, Seekatz AM. Butyrate enhances Clostridioides difficile sporulation in vitro. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.04.27.538596. [PMID: 37163089 PMCID: PMC10168334 DOI: 10.1101/2023.04.27.538596] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/11/2023]
Abstract
Short chain fatty acids (SCFAs) are products of bacterial fermentation that help maintain important gut functions such as the intestinal barrier, signaling, and immune homeostasis. The main SCFAs acetate, propionate, and butyrate have demonstrated beneficial effects for the host, including importance in combatting infections caused by pathogens such as Clostridioides difficile . Despite the potential role of SCFAs in mitigating C. difficile infection, their direct effect on C. difficile remains unclear. Through a set of in vitro experiments, we investigated how SCFAs influence C. difficile growth, sporulation, and toxin production. Similar to previous studies, we observed that butyrate decreased growth of C. difficile strain 630 in a dose-dependent manner. The presence of butyrate also increased C. difficile sporulation, with minimal increases in toxin production. RNA-Seq analysis validated our experimental results, demonstrating increased expression of sporulation-related genes in conjunction with alternative metabolic and related C. difficile regulatory pathways, such as the carbon catabolite repressor, CcpA. Collectively, these data suggest that butyrate may signal alternative C. difficile metabolic pathways, thus modifying its growth and virulence to persist in the gut environment. IMPORTANCE Several studies suggest that butyrate may be important in alleviating gut infections, such as reducing inflammation caused by the healthcare-associated Clostridioides difficile . While studies in both animal models and human studies correlate high levels of butyrate with reduced C. difficile burden, the direct impact of butyrate on C. difficile remains unclear. Our study demonstrates that butyrate directly influences C. difficile by increasing its sporulation and modifying its metabolism, potentially using butyrate as a biomarker to shift survival strategies in a changing gut environment. These data point to additional therapeutic approaches to combat C. difficile in a butyrate-directed manner.
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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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Qi P, Wang N, Zhang T, Feng Y, Zhou X, Zeng D, Meng J, Liu L, Jin L, Yang S. Anti-Virulence Strategy of Novel Dehydroabietic Acid Derivatives: Design, Synthesis, and Antibacterial Evaluation. Int J Mol Sci 2023; 24:2897. [PMID: 36769220 PMCID: PMC9917773 DOI: 10.3390/ijms24032897] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2022] [Revised: 01/27/2023] [Accepted: 01/28/2023] [Indexed: 02/05/2023] Open
Abstract
Anti-virulence strategies are attractive and interesting strategies for controlling bacterial diseases because virulence factors are fundamental to the infection process of numerous serious phytopathogenics. To extend the novel anti-virulence agents, a series of dehydroabietic acid (DAA) derivatives decorated with amino alcohol unit were semi-synthesized based on structural modification of the renewable natural DAA and evaluated for their antibacterial activity against Xanthomonas oryzae pv. oryzae (Xoo), Xanthomonas axonopodis pv. citri (Xac), and Pseudomonas syringae pv. actinidiae (Psa). Compound 2b showed the most promising antibacterial activity against Xoo with an EC50 of 2.7 μg mL-1. Furthermore, compound 2b demonstrated remarkable control effectiveness against bacterial leaf blight (BLB) in rice, with values of 48.6% and 61.4% for curative and protective activities. In addition, antibacterial behavior suggested that compound 2b could suppress various virulence factors, including EPS, biofilm, swimming motility, and flagella. Therefore, the current study provided promising lead compounds for novel bactericides discovery by inhibiting bacterial virulence factors.
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Affiliation(s)
| | | | | | | | - Xiang Zhou
- National Key Laboratory of Green Pesticide, Key Laboratory of Green Pesticide and Agricultural Bioengineering, Ministry of Education, Center for R&D of Fine Chemicals of Guizhou University, Guiyang 550025, China
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16
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Oberkampf M, Hamiot A, Altamirano-Silva P, Bellés-Sancho P, Tremblay YDN, DiBenedetto N, Seifert R, Soutourina O, Bry L, Dupuy B, Peltier J. c-di-AMP signaling is required for bile salt resistance, osmotolerance, and long-term host colonization by Clostridioides difficile. Sci Signal 2022; 15:eabn8171. [PMID: 36067333 PMCID: PMC9831359 DOI: 10.1126/scisignal.abn8171] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
To colonize the host and cause disease, the human enteropathogen Clostridioides difficile must sense, respond, and adapt to the harsh environment of the gastrointestinal tract. We showed that the production and degradation of cyclic diadenosine monophosphate (c-di-AMP) were necessary during different phases of C. difficile growth, environmental adaptation, and infection. The production of this nucleotide second messenger was essential for growth because it controlled the uptake of potassium and also contributed to biofilm formation and cell wall homeostasis, whereas its degradation was required for osmotolerance and resistance to detergents and bile salts. The c-di-AMP binding transcription factor BusR repressed the expression of genes encoding the compatible solute transporter BusAA-AB. Compared with the parental strain, a mutant lacking BusR was more resistant to hyperosmotic and bile salt stresses, whereas a mutant lacking BusAA was more susceptible. A short exposure of C. difficile cells to bile salts decreased intracellular c-di-AMP concentrations, suggesting that changes in membrane properties induce alterations in the intracellular c-di-AMP concentration. A C. difficile strain that could not degrade c-di-AMP failed to persist in a mouse gut colonization model as long as the wild-type strain did. Thus, the production and degradation of c-di-AMP in C. difficile have pleiotropic effects, including the control of osmolyte uptake to confer osmotolerance and bile salt resistance, and its degradation is important for host colonization.
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Affiliation(s)
- Marine Oberkampf
- Institut Pasteur, Université Paris Cité, UMR-CNRS 6047, Laboratoire Pathogenèse des Bactéries Anaérobies, F-75015 Paris, France
| | - Audrey Hamiot
- Institut Pasteur, Université Paris Cité, UMR-CNRS 6047, Laboratoire Pathogenèse des Bactéries Anaérobies, F-75015 Paris, France
| | - Pamela Altamirano-Silva
- Centro de Investigación en Enfermedades Tropicales, Facultad de Microbiología, Universidad de Costa Rica, San José, Costa Rica
| | - Paula Bellés-Sancho
- Institut Pasteur, Université Paris Cité, UMR-CNRS 6047, Laboratoire Pathogenèse des Bactéries Anaérobies, F-75015 Paris, France
| | - Yannick D. N. Tremblay
- Institut Pasteur, Université Paris Cité, UMR-CNRS 6047, Laboratoire Pathogenèse des Bactéries Anaérobies, F-75015 Paris, France
| | - Nicholas DiBenedetto
- Massachusetts Host-Microbiome Center, Department of Pathology, Brigham and Women’s Hospital, Harvard Medical School, Boston, MA, USA
| | - Roland Seifert
- Institute of Pharmacology and Research Core Unit Metabolomics, Hannover Medical School, Hannover, Germany
| | - Olga Soutourina
- Université Paris-Saclay, CEA, CNRS, Institute for Integrative Biology of the Cell (I2BC), 91198 Gif-sur-Yvette, France
| | - Lynn Bry
- Massachusetts Host-Microbiome Center, Department of Pathology, Brigham and Women’s Hospital, Harvard Medical School, Boston, MA, USA
- Clinical Microbiology Laboratory, Department of Pathology, Brigham and Women’s Hospital, Boston, MA, USA
| | - Bruno Dupuy
- Institut Pasteur, Université Paris Cité, UMR-CNRS 6047, Laboratoire Pathogenèse des Bactéries Anaérobies, F-75015 Paris, France
| | - Johann Peltier
- Institut Pasteur, Université Paris Cité, UMR-CNRS 6047, Laboratoire Pathogenèse des Bactéries Anaérobies, F-75015 Paris, France
- Université Paris-Saclay, CEA, CNRS, Institute for Integrative Biology of the Cell (I2BC), 91198 Gif-sur-Yvette, France
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17
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Reyes Ruiz LM, King KA, Agosto-Burgos C, Gamez IS, Gadda NC, Garrett EM, Tamayo R. Coordinated modulation of multiple processes through phase variation of a c-di-GMP phosphodiesterase in Clostridioides difficile. PLoS Pathog 2022; 18:e1010677. [PMID: 35789350 PMCID: PMC9286219 DOI: 10.1371/journal.ppat.1010677] [Citation(s) in RCA: 6] [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: 11/08/2021] [Revised: 07/15/2022] [Accepted: 06/15/2022] [Indexed: 11/19/2022] Open
Abstract
The opportunistic nosocomial pathogen Clostridioides difficile exhibits phenotypic heterogeneity through phase variation, a stochastic, reversible process that modulates expression. In C. difficile, multiple sequences in the genome undergo inversion through site-specific recombination. Two such loci lie upstream of pdcB and pdcC, which encode phosphodiesterases (PDEs) that degrade the signaling molecule c-di-GMP. Numerous phenotypes are influenced by c-di-GMP in C. difficile including cell and colony morphology, motility, colonization, and virulence. In this study, we aimed to assess whether PdcB phase varies, identify the mechanism of regulation, and determine the effects on intracellular c-di-GMP levels and regulated phenotypes. We found that expression of pdcB is heterogeneous and the orientation of the invertible sequence, or ‘pdcB switch’, determines expression. The pdcB switch contains a promoter that when properly oriented promotes pdcB expression. Expression is augmented by an additional promoter upstream of the pdcB switch. Mutation of nucleotides at the site of recombination resulted in phase-locked strains with significant differences in pdcB expression. Characterization of these mutants showed that the pdcB locked-ON mutant has reduced intracellular c-di-GMP compared to the locked-OFF mutant, consistent with increased and decreased PdcB activity, respectively. These alterations in c-di-GMP had concomitant effects on multiple known c-di-GMP regulated processes, indicating that phase variation of PdcB allows C. difficile to coordinately diversify multiple phenotypes in the population to enhance survival. Phase variation is a mechanism by which many bacteria introduce phenotypic heterogeneity into a population as a bet-hedging strategy to help ensure survival under detrimental conditions. In C. difficile, the intracellular signaling molecule c-di-GMP regulates production of flagella, toxins, adhesins, and other factors that impact virulence. C. difficile encodes multiple c-di-GMP synthases and hydrolases that modulate intracellular c-di-GMPs and control these processes. Here, we show that production of a c-di-GMP hydrolytic enzyme, PdcB, undergoes phase variation in C. difficile. We generated phase-locked mutants unable to phase vary and found that PdcB affects global intracellular c-di-GMP levels, swimming and surface motility, and biofilm formation. These findings suggest that phase variation of PdcB enables C. difficile to coordinately regulate the production multiple factors by generating heterogeneity in intracellular c-di-GMP levels among bacteria in the population.
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Affiliation(s)
- Leila M. Reyes Ruiz
- Department of Microbiology and Immunology, University of North Carolina School of Medicine, Chapel Hill, North Carolina, United States of America
| | - Kathleen A. King
- Department of Microbiology and Immunology, University of North Carolina School of Medicine, Chapel Hill, North Carolina, United States of America
| | - Christian Agosto-Burgos
- Department of Pathology and Laboratory Medicine, University of North Carolina School of Medicine, Chapel Hill, North Carolina, United States of America
| | - Isabella S. Gamez
- Department of Microbiology and Immunology, University of North Carolina School of Medicine, Chapel Hill, North Carolina, United States of America
| | - Nicole C. Gadda
- Department of Microbiology and Immunology, University of North Carolina School of Medicine, Chapel Hill, North Carolina, United States of America
| | - Elizabeth M. Garrett
- Department of Microbiology and Immunology, University of North Carolina School of Medicine, Chapel Hill, North Carolina, United States of America
| | - Rita Tamayo
- Department of Microbiology and Immunology, University of North Carolina School of Medicine, Chapel Hill, North Carolina, United States of America
- * E-mail:
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18
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Development of a Dual-Fluorescent-Reporter System in Clostridioides difficile Reveals a Division of Labor between Virulence and Transmission Gene Expression. mSphere 2022; 7:e0013222. [PMID: 35638354 PMCID: PMC9241537 DOI: 10.1128/msphere.00132-22] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
The bacterial pathogen Clostridioides difficile causes gastroenteritis by producing toxins and transmits disease by making resistant spores. Toxin and spore production are energy-expensive processes that are regulated by multiple transcription factors in response to many environmental inputs. While toxin and sporulation genes are both induced in only a subset of C. difficile cells, the relationship between these two subpopulations remains unclear. To address whether C. difficile coordinates the generation of these subpopulations, we developed a dual-transcriptional-reporter system that allows toxin and sporulation gene expression to be simultaneously visualized at the single-cell level using chromosomally encoded mScarlet and mNeonGreen fluorescent transcriptional reporters. We then adapted an automated image analysis pipeline to quantify toxin and sporulation gene expression in thousands of individual cells under different medium conditions and in different genetic backgrounds. These analyses revealed that toxin and sporulation gene expression rarely overlap during growth on agar plates, whereas broth culture increases this overlap. Our results suggest that certain growth conditions promote a “division of labor” between transmission and virulence gene expression, highlighting how environmental inputs influence these subpopulations. Our data further suggest that the RstA transcriptional regulator skews the population to activate sporulation genes rather than toxin genes. Given that recent work has revealed population-wide heterogeneity for numerous cellular processes in C. difficile, we anticipate that our dual-reporter system will be broadly useful for determining the overlap between these subpopulations. IMPORTANCEClostridioides difficile is an important nosocomial pathogen that causes severe diarrhea by producing toxins and transmits disease by producing spores. While both processes are crucial for C. difficile disease, only a subset of cells express toxins and/or undergo sporulation. Whether C. difficile coordinates the subset of cells inducing these energy-expensive processes remains unknown. To address this question, we developed a dual-fluorescent-reporter system coupled with an automated image analysis pipeline to rapidly compare the expression of two genes of interest across thousands of cells. Using this system, we discovered that certain growth conditions, particularly growth on agar plates, induce a “division of labor” between toxin and sporulation gene expression. Since C. difficile exhibits phenotypic heterogeneity for numerous vital cellular processes, this novel dual-reporter system will enable future studies aimed at understanding how C. difficile coordinates various subpopulations throughout its infectious disease cycle.
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Trzilova D, Warren MAH, Gadda NC, Williams CL, Tamayo R. Flagellum and toxin phase variation impacts intestinal colonization and disease development in a mouse model of Clostridioides difficile infection. Gut Microbes 2022; 14:2038854. [PMID: 35192433 PMCID: PMC8890394 DOI: 10.1080/19490976.2022.2038854] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
Clostridioides difficile is a major nosocomial pathogen that can cause severe, toxin-mediated diarrhea and pseudomembranous colitis. Recent work has shown that C. difficile exhibits heterogeneity in swimming motility and toxin production in vitro through phase variation by site-specific DNA recombination. The recombinase RecV reversibly inverts the flagellar switch sequence upstream of the flgB operon, leading to the ON/OFF expression of flagellum and toxin genes. How this phenomenon impacts C. difficile virulence in vivo remains unknown. We identified mutations in the right inverted repeat that reduced or prevented flagellar switch inversion by RecV. We introduced these mutations into C. difficile R20291 to create strains with the flagellar switch "locked" in either the ON or OFF orientation. These mutants exhibited a loss of flagellum and toxin phase variation during growth in vitro, yielding precisely modified mutants suitable for assessing virulence in vivo. In a hamster model of acute C. difficile infection, the phase-locked ON mutant caused greater toxin accumulation than the phase-locked OFF mutant but did not differ significantly in the ability to cause acute disease symptoms. In contrast, in a mouse model, preventing flagellum and toxin phase variation affected the ability of C. difficile to colonize the intestinal tract and to elicit weight loss, which is attributable to differences in toxin production during infection. These results show that the ability of C. difficile to phase vary flagella and toxins influences colonization and disease development and suggest that the phenotypic variants generated by flagellar switch inversion have distinct capacities for causing disease.
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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, NC, USA
| | - Mercedes A. H. Warren
- Department of Microbiology and Immunology, University of North Carolina at Chapel Hill School of Medicine, Chapel Hill, NC, USA
| | - Nicole C. Gadda
- Department of Microbiology and Immunology, University of North Carolina at Chapel Hill School of Medicine, Chapel Hill, NC, USA
| | - Caitlin L. Williams
- 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,CONTACT Rita Tamayo 125 Mason Farm Rd, CB #7290, Chapel Hill, NC27599-7290
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Abstract
The ability of the anaerobic gastrointestinal pathogen Clostridioides difficile to survive outside the host relies on the formation of dormant endospores. Spore formation is contingent on the activation of a conserved transcription factor, Spo0A, by phosphorylation. Multiple kinases and phosphatases regulate Spo0A activity in other spore-forming organisms; however, these factors are not well conserved in C. difficile. Previously, we discovered that deletion of a predicted histidine kinase, CD1492, increases sporulation, indicating that CD1492 inhibits C. difficile spore formation. In this study, we investigate the functions of additional predicted orphan histidine kinases CD2492, CD1579, and CD1949, which are hypothesized to regulate Spo0A phosphorylation. Disruption of CD2492 also increased sporulation frequency, similarly to the CD1492 mutant and in contrast to a previous study. A CD1492 CD2492 mutant phenocopied the sporulation and gene expression patterns of the single mutants, suggesting that these proteins function in the same genetic pathway to repress sporulation. Deletion of CD1579 variably increased sporulation frequency; however, knockdown of CD1949 expression did not influence sporulation. We provide evidence that CD1492, CD2492, and CD1579 function as phosphatases, as mutation of the conserved histidine residue for phosphate transfer abolished CD2492 function, and expression of the CD1492 or CD2492 histidine site-directed mutants or the wild-type CD1579 allele in a parent strain resulted in a dominant-negative hypersporulation phenotype. Altogether, at least three predicted histidine kinases, CD1492, CD2492, and CD1579 (herein, PtpA, PtpB and PtpC), repress C. difficile sporulation initiation by regulating activity of Spo0A. IMPORTANCE The formation of inactive spores is critical for the long-term survival of the gastrointestinal pathogen Clostridioides difficile. The onset of sporulation is controlled by the master regulator of sporulation, Spo0A, which is activated by phosphorylation. Multiple kinases and phosphatases control Spo0A phosphorylation; however, this regulatory pathway is not defined in C. difficile. We show that two predicted histidine kinase proteins, CD1492 (PtpA) and CD2492 (PtpB), function in the same regulatory pathway to repress sporulation by preventing Spo0A phosphorylation. We show that another predicted histidine kinase protein, CD1579 (PtpC), also represses sporulation and present evidence that a fourth predicted histidine kinase protein, CD1949, does not impact sporulation. These results support the idea that C. difficile inhibits sporulation initiation through multiple phosphatases.
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Liu X, Wang X, Sun B, Sun L. The Involvement of Thiamine Uptake in the Virulence of Edwardsiella piscicida. Pathogens 2022; 11:pathogens11040464. [PMID: 35456139 PMCID: PMC9026889 DOI: 10.3390/pathogens11040464] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2022] [Revised: 04/11/2022] [Accepted: 04/11/2022] [Indexed: 11/16/2022] Open
Abstract
Edwardsiella piscicida is a pathogenic bacterium, which can infect a number of fish species and cause a disease termed edwardsiellosis, threatening global fish farming with high prevalence and mortality. Thiamine (Vitamin B1), functioning in the form of thiamine pyrophosphate (TPP), is essential for almost all organisms. Bacteria acquire TPP by biosynthesis or by transportation of exogenous thiamine. TPP availability has been associated with bacterial pathogenicity, but the underlying mechanisms remain to be discovered. The role of thiamine in the pathogenicity of E. piscicida is unknown. In this study, we characterized a thiamine transporter (TT) operon in E. piscicida. The deletion of the TT operon resulted in an intracellular TPP lacking situation, which led to attenuated overall pathogenicity, impaired abilities associated with motility and host cell adhesion, as well as decreased expression of certain flagellar and adhesion genes. Moreover, TPP starvation led to intracellular c-di-GMP reduction, and introducing into the TPP-suppressed mutant strain an exogenous diguanylate cyclase for c-di-GMP synthesis restored the virulence loss. Taken together, this work reveals the involvement of thiamine uptake in the virulence regulation of E. piscicida, with c-di-GMP implicated in the process. These finding could be employed to explore potential drug targets against E. piscicida.
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Affiliation(s)
- Xin Liu
- CAS and Shandong Province Key Laboratory of Experimental Marine Biology, Institute of Oceanology, CAS Center for Ocean Mega-Science, Chinese Academy of Sciences, Qingdao 266071, China; (X.L.); (X.W.)
- Laboratory for Marine Biology and Biotechnology, Pilot National Laboratory for Marine Science and Technology, Qingdao 266003, China
- College of Earth and Planetary Sciences, University of Chinese Academy of Sciences, Beijing 100049, China
| | - Xinhui Wang
- CAS and Shandong Province Key Laboratory of Experimental Marine Biology, Institute of Oceanology, CAS Center for Ocean Mega-Science, Chinese Academy of Sciences, Qingdao 266071, China; (X.L.); (X.W.)
| | - Boguang Sun
- CAS and Shandong Province Key Laboratory of Experimental Marine Biology, Institute of Oceanology, CAS Center for Ocean Mega-Science, Chinese Academy of Sciences, Qingdao 266071, China; (X.L.); (X.W.)
- Laboratory for Marine Biology and Biotechnology, Pilot National Laboratory for Marine Science and Technology, Qingdao 266003, China
- Correspondence: (B.S.); (L.S.)
| | - Li Sun
- CAS and Shandong Province Key Laboratory of Experimental Marine Biology, Institute of Oceanology, CAS Center for Ocean Mega-Science, Chinese Academy of Sciences, Qingdao 266071, China; (X.L.); (X.W.)
- Laboratory for Marine Biology and Biotechnology, Pilot National Laboratory for Marine Science and Technology, Qingdao 266003, China
- College of Earth and Planetary Sciences, University of Chinese Academy of Sciences, Beijing 100049, China
- Correspondence: (B.S.); (L.S.)
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22
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Regulation of Clostridioides difficile toxin production. Curr Opin Microbiol 2022; 65:95-100. [PMID: 34781095 PMCID: PMC8792210 DOI: 10.1016/j.mib.2021.10.018] [Citation(s) in RCA: 20] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2021] [Revised: 10/19/2021] [Accepted: 10/25/2021] [Indexed: 02/03/2023]
Abstract
Clostridioides difficile produces toxins TcdA and TcdB during infection. Since the severity of the illness is directly correlated with the level of toxins produced, researchers have long been interested in the regulation mechanisms of toxin production. The advent of new genetics and mutagenesis technologies in C. difficile has allowed a slew of new investigations in the last decade, which considerably improved our understanding of this crucial regulatory network. The current body of work shows that the toxin regulatory network overlaps with the regulatory networks of sporulation, motility, and key metabolic pathways. This implies that toxin production is a complicated process initiated by bacteria in response to numerous host factors during infection. We summarize the existing knowledge about the toxin gene regulatory network here.
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Edwards AN, Willams CL, Pareek N, McBride SM, Tamayo R. c-di-GMP Inhibits Early Sporulation in Clostridioides difficile. mSphere 2021; 6:e0091921. [PMID: 34878288 PMCID: PMC8653836 DOI: 10.1128/msphere.00919-21] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2021] [Accepted: 11/19/2021] [Indexed: 12/02/2022] Open
Abstract
The formation of dormant spores is essential for the anaerobic pathogen Clostridioides difficile to survive outside the host gastrointestinal tract. The regulatory pathways and environmental signals that initiate C. difficile spore formation within the host are not well understood. One second-messenger signaling molecule, cyclic diguanylate (c-di-GMP), modulates several physiological processes important for C. difficile pathogenesis and colonization, but the impact of c-di-GMP on sporulation is unknown. In this study, we investigated the contribution of c-di-GMP to C. difficile sporulation. The overexpression of a gene encoding a diguanylate cyclase, dccA, decreased the sporulation frequency and early sporulation gene transcription in both the epidemic R20291 and historical 630Δerm strains. The expression of a dccA allele encoding a catalytically inactive DccA that is unable to synthesize c-di-GMP no longer inhibited sporulation, indicating that the accumulation of intracellular c-di-GMP reduces C. difficile sporulation. A null mutation in dccA slightly increased sporulation in R20291 and slightly decreased sporulation in 630Δerm, suggesting that DccA contributes to the intracellular pool of c-di-GMP in a strain-dependent manner. However, these data were highly variable, underscoring the complex regulation involved in modulating intracellular c-di-GMP concentrations. Finally, the overexpression of dccA in known sporulation mutants revealed that c-di-GMP is likely signaling through an unidentified regulatory pathway to control early sporulation events in C. difficile. c-di-GMP-dependent regulation of C. difficile sporulation may represent an unexplored avenue of potential environmental and intracellular signaling that contributes to the complex regulation of sporulation initiation. IMPORTANCE Many bacterial organisms utilize the small signaling molecule cyclic diguanylate (c-di-GMP) to regulate important physiological processes, including motility, toxin production, biofilm formation, and colonization. c-di-GMP inhibits motility and toxin production and promotes biofilm formation and colonization in the anaerobic, gastrointestinal pathogen Clostridioides difficile. However, the impact of c-di-GMP on C. difficile spore formation, a critical step in this pathogen's life cycle, is unknown. Here, we demonstrate that c-di-GMP negatively impacts sporulation in two clinically relevant C. difficile strains, the epidemic strain R20291 and the historical strain 630Δerm. The pathway through which c-di-GMP controls sporulation was investigated, and our results suggest that c-di-GMP is likely signaling through an unidentified regulatory pathway to control C. difficile sporulation. This work implicates c-di-GMP metabolism as a mechanism to integrate environmental and intracellular cues through c-di-GMP levels to influence C. difficile sporulation.
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Affiliation(s)
- Adrianne N. Edwards
- Department of Microbiology and Immunology, Emory University School of Medicine, Emory Antibiotic Resistance Center, Atlanta, Georgia, USA
| | - Caitlin L. Willams
- Department of Microbiology and Immunology, University of North Carolina—Chapel Hill, Chapel Hill, North Carolina, USA
| | - Nivedita Pareek
- Department of Microbiology and Immunology, University of North Carolina—Chapel Hill, Chapel Hill, North Carolina, USA
| | - Shonna M. McBride
- Department of Microbiology and Immunology, Emory University School of Medicine, Emory Antibiotic Resistance Center, Atlanta, Georgia, USA
| | - Rita Tamayo
- Department of Microbiology and Immunology, University of North Carolina—Chapel Hill, Chapel Hill, North Carolina, USA
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Purcell EB. Second messenger signaling in Clostridioides difficile. Curr Opin Microbiol 2021; 65:138-144. [PMID: 34864551 DOI: 10.1016/j.mib.2021.11.006] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2021] [Revised: 11/09/2021] [Accepted: 11/10/2021] [Indexed: 12/18/2022]
Abstract
Small, diffusible second messenger molecules transmit information about extracellular conditions to intracellular machinery in order to influence transcription, translation, and metabolism. The enteropathogenic bacterium Clostridioides difficile coordinates its response to a dynamic and hostile environment via nucleotide second messengers. While riboswitch-mediated cyclic diguanylate regulation has been extensively characterized in C. difficile, signaling by cyclic diadenylate and by guanosine alarmones has only recently been confirmed in this organism. This review summarizes the current knowledge of how nucleotide second messenger signaling regulates physiological processes in C. difficile.
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Affiliation(s)
- Erin B Purcell
- Old Dominion University, Department of Chemistry and Biochemistry, 4501 Elkhorn Ave, Norfolk, VA 23529, United States.
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Zhu D, Wang S, Sun X. FliW and CsrA Govern Flagellin (FliC) Synthesis and Play Pleiotropic Roles in Virulence and Physiology of Clostridioides difficile R20291. Front Microbiol 2021; 12:735616. [PMID: 34675903 PMCID: PMC8523840 DOI: 10.3389/fmicb.2021.735616] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2021] [Accepted: 09/13/2021] [Indexed: 02/04/2023] Open
Abstract
Clostridioides difficile flagellin FliC is associated with toxin gene expression, bacterial colonization, and virulence, and is also involved in pleiotropic gene regulation during in vivo infection. However, how fliC expression is regulated in C. difficile remains unclear. In Bacillus subtilis, flagellin homeostasis and motility are coregulated by flagellar assembly factor (FliW), flagellin Hag (FliC homolog), and Carbon storage regulator A (CsrA), which is referred to as partner-switching mechanism “FliW-CsrA-Hag.” In this study, we characterized FliW and CsrA functions by deleting or overexpressing fliW, csrA, and fliW-csrA in C. difficile R20291. We showed that fliW deletion, csrA overexpression in R20291, and csrA complementation in R20291ΔWA (fliW-csrA codeletion mutant) dramatically decreased FliC production, but not fliC gene transcription. Suppression of fliC translation by csrA overexpression can be relieved mostly when fliW was coexpressed, and no significant difference in FliC production was detected when only fliW was complemented in R20291ΔWA. Further, loss of fliW led to increased biofilm formation, cell adhesion, toxin production, and pathogenicity in a mouse model of C. difficile infection (CDI), while fliW-csrA codeletion decreased toxin production and mortality in vivo. Our data suggest that CsrA negatively modulates fliC expression and FliW indirectly affects fliC expression through inhibition of CsrA post-transcriptional regulation. In light of “FliW-CsrA-Hag” switch coregulation mechanism reported in B. subtilis, our data also suggest that “FliW-CsrA-fliC/FliC” can regulate many facets of C. difficile R20291 pathogenicity. These findings further aid us in understanding the virulence regulation in C. difficile.
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Affiliation(s)
- Duolong Zhu
- Department of Molecular Medicine, Morsani College of Medicine, University of South Florida, Tampa, FL, United States
| | - Shaohui Wang
- Department of Molecular Medicine, Morsani College of Medicine, University of South Florida, Tampa, FL, United States
| | - Xingmin Sun
- Department of Molecular Medicine, Morsani College of Medicine, University of South Florida, Tampa, FL, United States
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Dhungel BA, Govind R. Phase-variable expression of pdcB, a phosphodiesterase, influences sporulation in Clostridioides difficile. Mol Microbiol 2021; 116:1347-1360. [PMID: 34606654 DOI: 10.1111/mmi.14828] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2021] [Revised: 09/30/2021] [Accepted: 10/01/2021] [Indexed: 02/07/2023]
Abstract
Clostridioides difficile is the causative agent of antibiotic-associated diarrhea and is the leading cause of nosocomial infection in developed countries. An increasing number of C. difficile infections are attributed to epidemic strains that produce more toxins and spores. C. difficile spores are the major factor for the transmission and persistence of the organism. Previous studies have identified global regulators that influence sporulation in C. difficile. This study discovers that PdcB, a phosphodiesterase, enhances sporulation in C. difficile strain UK1. Through genetic and biochemical assays, we show that phase-variable expression of pdcB results in hypo- and hyper-sporulation phenotypes. In the "ON" orientation, the identified promotor is in the right orientation to drive the expression of pdcB. Production of the PdcB phosphodiesterase reduces the intracellular cyclic-di-GMP (c-di-GMP) concentration, resulting in a hyper-sporulation phenotype. Loss of PdcB due to the pdcB promoter being in the OFF orientation or mutation of pdcB results in increased c-di-GMP levels and a hypo-sporulation phenotype. Additionally, we demonstrate that CodY binds to the upstream region of pdcB. DNA inversion reorients the CodY binding site so that in the OFF orientation, CodY binds a site that is upstream of the pdcB promoter and can further repress gene expression.
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Affiliation(s)
| | - Revathi Govind
- Division of Biology, Kansas State University, Manhattan, Kansas, USA
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Abstract
Clostridiodes difficile (C. difficile) was ranked an “urgent threat” by the Centers for Disease Control and Prevention (CDC) in 2019. C. difficile infection (CDI) is the most common healthcare-associated infection (HAI) in the United States of America as well as the leading cause of antibiotic-associated gastrointestinal disease. C. difficile is a gram-positive, rod-shaped, spore-forming, anaerobic bacterium that causes infection of the epithelial lining of the gut. CDI occurs most commonly after disruption of the human gut microflora following the prolonged use of broad-spectrum antibiotics. However, the recurrent nature of this disease has led to the hypothesis that biofilm formation may play a role in its pathogenesis. Biofilms are sessile communities of bacteria protected from extracellular stresses by a matrix of self-produced proteins, polysaccharides, and extracellular DNA. Biofilm regulation in C. difficile is still incompletely understood, and its role in disease recurrence has yet to be fully elucidated. However, many factors have been found to influence biofilm formation in C. difficile, including motility, adhesion, and hydrophobicity of the bacterial cells. Small changes in one of these systems can greatly influence biofilm formation. Therefore, the biofilm regulatory system would need to coordinate all these systems to create optimal biofilm-forming physiology under appropriate environmental conditions. The coordination of these systems is complex and multifactorial, and any analysis must take into consideration the influences of the stress response, quorum sensing (QS), and gene regulation by second messenger molecule cyclic diguanosine monophosphate (c-di-GMP). However, the differences in biofilm-forming ability between C. difficile strains such as 630 and the “hypervirulent” strain, R20291, make it difficult to assign a “one size fits all” mechanism to biofilm regulation in C. difficile. This review seeks to consolidate published data regarding the regulation of C. difficile biofilms in order to identify gaps in knowledge and propose directions for future study. Clostridioides difficile (C. difficile) is an opportunistic bacterial pathogen that causes infection of the human gut epithelium following disruption of the normal gut microflora, usually by broad-spectrum antibiotics. C. difficile infection (CDI) is recurrent in 20% to 30% of cases and can lead to significant health-related complications such as pseudomembranous colitis and, in severe cases, death. The impact and cost of this pathogen on healthcare systems are significant, and some aspects of the pathogen’s lifestyle in the host are, as yet, unknown. It is hypothesised that C. difficile exists in the gut as a biofilm due to the infection’s severity and recurrent nature. The biofilm mode of bacterial growth can protect the cells from external factors such as antibiotic treatment, physiological processes, and the immune system. However, biofilm regulation in C. difficile is not yet fully characterised, and in this review, we consolidate published primary research on C. difficile biofilm regulation to gain a comprehensive overview of the factors involved and how they may interact to enable biofilm development within a host.
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Hasan MK, Dhungel BA, Govind R. Characterization of an operon required for growth on cellobiose in Clostridioides difficile. MICROBIOLOGY-SGM 2021; 167. [PMID: 34410904 DOI: 10.1099/mic.0.001079] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Cellobiose metabolism is linked to the virulence properties in numerous bacterial pathogens. Here, we characterized a putative cellobiose PTS operon of Clostridiodes difficile to investigate the role of cellobiose metabolism in C. difficile pathogenesis. Our gene knockout experiments demonstrated that the putative cellobiose operon enables uptake of cellobiose into C. difficile and allows growth when cellobiose is provided as the sole carbon source in minimal medium. Additionally, using reporter gene fusion assays and DNA pulldown experiments, we show that its transcription is regulated by CelR, a novel transcriptional repressor protein, which directly binds to the upstream region of the cellobiose operon to control its expression. We have also identified cellobiose metabolism to play a significant role in C. difficile physiology as observed by the reduction of sporulation efficiency when cellobiose uptake was compromised in the mutant strain. In corroboration to in vitro study findings, our in vivo hamster challenge experiment showed a significant reduction of pathogenicity by the cellobiose mutant strain in both the primary and the recurrent infection model - substantiating the role of cellobiose metabolism in C. difficile pathogenesis.
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Affiliation(s)
- Md Kamrul Hasan
- Division of Biology, Kansas State University, Manhattan, KS, 66506, USA
| | | | - Revathi Govind
- Division of Biology, Kansas State University, Manhattan, KS, 66506, USA
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29
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Spore-Associated Proteins Involved in c-di-GMP Synthesis and Degradation of Bacillus anthracis. J Bacteriol 2021; 203:e0013521. [PMID: 34096779 DOI: 10.1128/jb.00135-21] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023] Open
Abstract
Bis-(3'-5')-cyclic-dimeric GMP (c-di-GMP) is an important bacterial regulatory signaling molecule affecting biofilm formation, toxin production, motility, and virulence. The genome of Bacillus anthracis, the causative agent of anthrax, is predicted to encode ten putative GGDEF/EAL/HD-GYP-domain containing proteins. Heterologous expression in Bacillus subtilis hosts indicated that there are five active GGDEF domain-containing proteins and four active EAL or HD-GYP domain-containing proteins. Using an mCherry gene fusion-Western blotting approach, the expression of the c-di-GMP-associated proteins was observed throughout the in vitro life cycle. Of the six c-di-GMP-associated proteins found to be present in sporulating cells, four (CdgA, CdgB, CdgD, and CdgG) contain active GGDEF domains. The six proteins expressed in sporulating cells are retained in spores in a CotE-independent manner and thus are not likely to be localized to the exosporium layer of the spores. Individual deletion mutations involving the nine GGDEF/EAL protein-encoding genes and one HD-GYP protein-encoding gene did not affect sporulation efficiency, the attachment of the exosporium glycoprotein BclA, or biofilm production. Notably, expression of anthrax toxin was not affected by deletion of any of the cdg determinants. Three determinants encoding proteins with active GGDEF domains were found to affect germination kinetics. This study reveals a spore association of cyclic-di-GMP regulatory proteins and a likely role for these proteins in the biology of the B. anthracis spore. IMPORTANCE The genus Bacillus is composed of Gram-positive, rod shaped, soil-dwelling bacteria. As a mechanism for survival in the harsh conditions in soil, the organisms undergo sporulation, and the resulting spores permit the organisms to survive harsh environmental conditions. Although most species are saprophytes, Bacillus cereus and Bacillus anthracis are human pathogens and Bacillus thuringiensis is an insect pathogen. The bacterial c-di-GMP regulatory system is an important control system affecting motility, biofilm formation, and toxin production. The role of c-di-GMP has been studied in the spore-forming bacilli Bacillus subtilis, Bacillus amyloliquefaciens, B. cereus, and B. thuringiensis. However, this regulatory system has not heretofore been examined in the high-consequence zoonotic pathogen of this genus, B. anthracis.
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An RNA-centric global view of Clostridioides difficile reveals broad activity of Hfq in a clinically important gram-positive bacterium. Proc Natl Acad Sci U S A 2021; 118:2103579118. [PMID: 34131082 PMCID: PMC8237595 DOI: 10.1073/pnas.2103579118] [Citation(s) in RCA: 23] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
The gram-positive human pathogen Clostridioides difficile has emerged as the leading cause of antibiotic-associated diarrhea. However, little is known about the bacterium's transcriptome architecture and mechanisms of posttranscriptional control. Here, we have applied transcription start site and termination mapping to generate a single-nucleotide-resolution RNA map of C. difficile 5' and 3' untranslated regions, operon structures, and noncoding regulators, including 42 sRNAs. Our results indicate functionality of many conserved riboswitches and predict cis-regulatory RNA elements upstream of multidrug resistance (MDR)-type ATP-binding cassette (ABC) transporters and transcriptional regulators. Despite growing evidence for a role of Hfq in RNA-based gene regulation in C. difficile, the functions of Hfq-based posttranscriptional regulatory networks in gram-positive pathogens remain controversial. Using Hfq immunoprecipitation followed by sequencing of bound RNA species (RIP-seq), we identify a large cohort of transcripts bound by Hfq and show that absence of Hfq affects transcript stabilities and steady-state levels. We demonstrate sRNA expression during intestinal colonization by C. difficile and identify infection-related signals impacting its expression. As a proof of concept, we show that the utilization of the abundant intestinal metabolite ethanolamine is regulated by the Hfq-dependent sRNA CDIF630nc_085. Overall, our study lays the foundation for understanding clostridial riboregulation with implications for the infection process and provides evidence for a global role of Hfq in posttranscriptional regulation in a gram-positive bacterium.
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Brauer M, Lassek C, Hinze C, Hoyer J, Becher D, Jahn D, Sievers S, Riedel K. What's a Biofilm?-How the Choice of the Biofilm Model Impacts the Protein Inventory of Clostridioides difficile. Front Microbiol 2021; 12:682111. [PMID: 34177868 PMCID: PMC8225356 DOI: 10.3389/fmicb.2021.682111] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2021] [Accepted: 05/12/2021] [Indexed: 12/18/2022] Open
Abstract
The anaerobic pathogen Clostridioides difficile is perfectly equipped to survive and persist inside the mammalian intestine. When facing unfavorable conditions C. difficile is able to form highly resistant endospores. Likewise, biofilms are currently discussed as form of persistence. Here a comprehensive proteomics approach was applied to investigate the molecular processes of C. difficile strain 630Δerm underlying biofilm formation. The comparison of the proteome from two different forms of biofilm-like growth, namely aggregate biofilms and colonies on agar plates, revealed major differences in the formation of cell surface proteins, as well as enzymes of its energy and stress metabolism. For instance, while the obtained data suggest that aggregate biofilm cells express both flagella, type IV pili and enzymes required for biosynthesis of cell-surface polysaccharides, the S-layer protein SlpA and most cell wall proteins (CWPs) encoded adjacent to SlpA were detected in significantly lower amounts in aggregate biofilm cells than in colony biofilms. Moreover, the obtained data suggested that aggregate biofilm cells are rather actively growing cells while colony biofilm cells most likely severely suffer from a lack of reductive equivalents what requires induction of the Wood-Ljungdahl pathway and C. difficile’s V-type ATPase to maintain cell homeostasis. In agreement with this, aggregate biofilm cells, in contrast to colony biofilm cells, neither induced toxin nor spore production. Finally, the data revealed that the sigma factor SigL/RpoN and its dependent regulators are noticeably induced in aggregate biofilms suggesting an important role of SigL/RpoN in aggregate biofilm formation.
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Affiliation(s)
- Madita Brauer
- Department for Microbial Physiology and Molecular Biology, Institute of Microbiology, University of Greifswald, Greifswald, Germany
| | - Christian Lassek
- Department for Microbial Physiology and Molecular Biology, Institute of Microbiology, University of Greifswald, Greifswald, Germany
| | - Christian Hinze
- Department for Microbial Physiology and Molecular Biology, Institute of Microbiology, University of Greifswald, Greifswald, Germany
| | - Juliane Hoyer
- Department for Microbial Proteomics, Institute of Microbiology, University of Greifswald, Greifswald, Germany
| | - Dörte Becher
- Department for Microbial Proteomics, Institute of Microbiology, University of Greifswald, Greifswald, Germany
| | - Dieter Jahn
- Braunschweig Integrated Centre of Systems Biology (BRICS), Institute of Microbiology, Technische Universität Braunschweig, Braunschweig, Germany
| | - Susanne Sievers
- Department for Microbial Physiology and Molecular Biology, Institute of Microbiology, University of Greifswald, Greifswald, Germany
| | - Katharina Riedel
- Department for Microbial Physiology and Molecular Biology, Institute of Microbiology, University of Greifswald, Greifswald, Germany
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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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Dawson LF, Peltier J, Hall CL, Harrison MA, Derakhshan M, Shaw HA, Fairweather NF, Wren BW. Extracellular DNA, cell surface proteins and c-di-GMP promote biofilm formation in Clostridioides difficile. Sci Rep 2021; 11:3244. [PMID: 33547340 PMCID: PMC7865049 DOI: 10.1038/s41598-020-78437-5] [Citation(s) in RCA: 30] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2020] [Accepted: 11/17/2020] [Indexed: 02/07/2023] Open
Abstract
Clostridioides difficile is the leading cause of nosocomial antibiotic-associated diarrhoea worldwide, yet there is little insight into intestinal tract colonisation and relapse. In many bacterial species, the secondary messenger cyclic-di-GMP mediates switching between planktonic phase, sessile growth and biofilm formation. We demonstrate that c-di-GMP promotes early biofilm formation in C. difficile and that four cell surface proteins contribute to biofilm formation, including two c-di-GMP regulated; CD2831 and CD3246, and two c-di-GMP-independent; CD3392 and CD0183. We demonstrate that C. difficile biofilms are composed of extracellular DNA (eDNA), cell surface and intracellular proteins, which form a protective matrix around C. difficile vegetative cells and spores, as shown by a protective effect against the antibiotic vancomycin. We demonstrate a positive correlation between biofilm biomass, sporulation frequency and eDNA abundance in all five C. difficile lineages. Strains 630 (RT012), CD305 (RT023) and M120 (RT078) contain significantly more eDNA in their biofilm matrix than strains R20291 (RT027) and M68 (RT017). DNase has a profound effect on biofilm integrity, resulting in complete disassembly of the biofilm matrix, inhibition of biofilm formation and reduced spore germination. The addition of exogenous DNase could be exploited in treatment of C. difficile infection and relapse, to improve antibiotic efficacy.
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Affiliation(s)
- Lisa F Dawson
- Department of Infection Biology, London School of Hygiene and Tropical Medicine, London, UK.
| | - Johann Peltier
- Department of Infection Biology, London School of Hygiene and Tropical Medicine, London, UK
- Université Paris-Saclay, CEA, CNRS, Institute for Integrative Biology of the Cell (I2BC), 91198, Gif-sur-Yvette, France
| | - Catherine L Hall
- Department of Infection Biology, London School of Hygiene and Tropical Medicine, London, UK
| | - Mark A Harrison
- Department of Infection Biology, London School of Hygiene and Tropical Medicine, London, UK
| | - Maria Derakhshan
- Department of Infection Biology, London School of Hygiene and Tropical Medicine, London, UK
| | - Helen A Shaw
- Department of Infection Biology, London School of Hygiene and Tropical Medicine, London, UK
- National Institute for Biological Standards and Control, Potters Bar, UK
| | - Neil F Fairweather
- Department of Life Sciences, Imperial College London, South Kensington Campus, London, SW7 2AZ, UK
| | - Brendan W Wren
- Department of Infection Biology, London School of Hygiene and Tropical Medicine, London, UK
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Abstract
Clostridioides difficile is the leading cause of nosocomial infection and is the causative agent of antibiotic-associated diarrhea. The severity of the disease is directly associated with toxin production, and spores are responsible for the transmission and persistence of the organism. Previously, we characterized sin locus regulators SinR and SinR' (we renamed it SinI), where SinR is the regulator of toxin production and sporulation. The SinI regulator acts as its antagonist. In Bacillus subtilis, Spo0A, the master regulator of sporulation, controls SinR by regulating the expression of its antagonist, sinI However, the role of Spo0A in the expression of sinR and sinI in C. difficile had not yet been reported. In this study, we tested spo0A mutants in three different C. difficile strains, R20291, UK1, and JIR8094, to understand the role of Spo0A in sin locus expression. Western blot analysis revealed that spo0A mutants had increased SinR levels. Quantitative reverse transcription-PCR (qRT-PCR) analysis of its expression further supported these data. By carrying out genetic and biochemical assays, we show that Spo0A can bind to the upstream region of this locus to regulates its expression. This study provides vital information that Spo0A regulates the sin locus, which controls critical pathogenic traits such as sporulation, toxin production, and motility in C. difficile IMPORTANCE Clostridioides difficile is the leading cause of antibiotic-associated diarrheal disease in the United States. During infection, C. difficile spores germinate, and the vegetative bacterial cells produce toxins that damage host tissue. In C. difficile, the sin locus is known to regulate both sporulation and toxin production. In this study, we show that Spo0A, the master regulator of sporulation, controls sin locus expression. Results from our study suggest that Spo0A directly regulates the expression of this locus by binding to its upstream DNA region. This observation adds new detail to the gene regulatory network that connects sporulation and toxin production in this pathogen.
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Trzilova D, Tamayo R. Site-Specific Recombination - How Simple DNA Inversions Produce Complex Phenotypic Heterogeneity in Bacterial Populations. Trends Genet 2020; 37:59-72. [PMID: 33008627 DOI: 10.1016/j.tig.2020.09.004] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2020] [Revised: 08/26/2020] [Accepted: 09/01/2020] [Indexed: 02/07/2023]
Abstract
Many bacterial species generate phenotypically heterogeneous subpopulations as a strategy for ensuring the survival of the population as a whole - an environmental stress that eradicates one subpopulation may leave other phenotypic groups unharmed, allowing the lineage to continue. Phase variation, a process that functions as an ON/OFF switch for gene expression, is one way that bacteria achieve phenotypic heterogeneity. Phase variation occurs stochastically and reversibly, and in the presence of a selective pressure the advantageous phenotype(s) predominates in the population. Phase variation can occur through multiple genetic and epigenetic mechanisms. This review focuses on conservative site-specific recombination that generates reversible DNA inversions as a genetic mechanism mediating phase variation. Recent studies have sparked a renewed interest in phase variation mediated through DNA inversion, revealing a high level of complexity beyond simple ON/OFF switching, including unusual modes of gene regulation, and highlighting an underappreciation of the use of these mechanisms by bacteria.
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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, 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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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. Phenotypic heterogeneity maintained by phase variation allows bacterial subpopulations to overcome potentially detrimental stresses in the environment, contributing to bacterial survival. Phase variation of flagella and toxins in C. difficile suggests that maintaining heterogeneity of their production may be important for survival and virulence. In this study, we identified Rho as a trans-acting factor that mediates the differential gene expression that imparts heterogeneity in flagellum and toxin production. These results reveal a new role for Rho-mediated transcription termination in regulation of gene expression.
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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
- * E-mail:
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Affiliation(s)
- Leila M. Reyes Ruiz
- Department of Microbiology and Immunology, University of North Carolina Chapel Hill, Chapel Hill, North Carolina, United States of America
| | - Caitlin L. Williams
- Department of Microbiology and Immunology, University of North Carolina Chapel Hill, Chapel Hill, North Carolina, United States of America
| | - Rita Tamayo
- Department of Microbiology and Immunology, University of North Carolina Chapel Hill, Chapel Hill, North Carolina, United States of America
- * E-mail:
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Valentini M, Filloux A. Multiple Roles of c-di-GMP Signaling in Bacterial Pathogenesis. Annu Rev Microbiol 2020; 73:387-406. [PMID: 31500536 DOI: 10.1146/annurev-micro-020518-115555] [Citation(s) in RCA: 80] [Impact Index Per Article: 20.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
The intracellular signaling molecule cyclic di-GMP (c-di-GMP) regulates the lifestyle of bacteria and controls many key functions and mechanisms. In the case of bacterial pathogens, a wide variety of virulence lifestyle factors have been shown to be regulated by c-di-GMP. Evidence of the importance of this molecule for bacterial pathogenesis has become so great that new antimicrobial agents are tested for their capacity of targeting c-di-GMP signaling. This review summarizes the current knowledge on this topic and reveals its application for the development of new antivirulence intervention strategies.
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Affiliation(s)
- Martina Valentini
- Department of Microbiology and Molecular Medicine, Faculty of Medicine, University of Geneva, CH-1211 Geneva 4, Switzerland;
| | - Alain Filloux
- MRC Centre for Molecular Microbiology and Infection, Department of Life Sciences, Imperial College London, SW7 2AZ London, United Kingdom;
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Strain-Dependent RstA Regulation of Clostridioides difficile Toxin Production and Sporulation. J Bacteriol 2020; 202:JB.00586-19. [PMID: 31659010 DOI: 10.1128/jb.00586-19] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2019] [Accepted: 10/21/2019] [Indexed: 02/04/2023] Open
Abstract
The anaerobic spore former Clostridioides difficile causes significant diarrheal disease in humans and other mammals. Infection begins with the ingestion of dormant spores, which subsequently germinate within the host gastrointestinal tract. There, the vegetative cells proliferate and secrete two exotoxins, TcdA and TcdB, which cause disease symptoms. Although spore formation and toxin production are critical for C. difficile pathogenesis, the regulatory links between these two physiological processes are not well understood and are strain dependent. Previously, we identified a conserved C. difficile regulator, RstA, that promotes sporulation initiation through an unknown mechanism and directly and indirectly represses toxin and motility gene transcription in the historical isolate 630Δerm To test whether perceived strain-dependent differences in toxin production and sporulation are mediated by RstA, we created an rstA mutant in the epidemic ribotype 027 strain R20291. RstA affected sporulation and toxin gene expression similarly but more robustly in R20291 than in 630Δerm In contrast, no effect on motility gene expression was observed in R20291. Reporter assays measuring transcriptional regulation of tcdR, the sigma factor gene essential for toxin gene expression, identified sequence-dependent effects influencing repression by RstA and CodY, a global nutritional sensor, in four diverse C. difficile strains. Finally, sequence- and strain-dependent differences were evident in RstA negative autoregulation of rstA transcription. Altogether, our data suggest that strain-dependent differences in RstA regulation contribute to the sporulation and toxin phenotypes observed in R20291. Our data establish RstA as an important regulator of C. difficile virulence traits.IMPORTANCE Two critical traits of Clostridioides difficile pathogenesis are toxin production, which causes disease symptoms, and spore formation, which permits survival outside the gastrointestinal tract. The multifunctional regulator RstA promotes sporulation and prevents toxin production in the historical strain 630Δerm Here, we show that RstA exhibits stronger effects on these phenotypes in an epidemic isolate, R20291, and additional strain-specific effects on toxin and rstA expression are evident. Our data demonstrate that sequence-specific differences within the promoter for the toxin regulator TcdR contribute to the regulation of toxin production by RstA and CodY. These sequence differences account for some of the variability in toxin production among isolates and may allow strains to differentially control toxin production in response to a variety of signals.
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Shen A, Edwards AN, Sarker MR, Paredes-Sabja D. Sporulation and Germination in Clostridial Pathogens. Microbiol Spectr 2019; 7:10.1128/microbiolspec.GPP3-0017-2018. [PMID: 31858953 PMCID: PMC6927485 DOI: 10.1128/microbiolspec.gpp3-0017-2018] [Citation(s) in RCA: 45] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2018] [Indexed: 12/14/2022] Open
Abstract
As obligate anaerobes, clostridial pathogens depend on their metabolically dormant, oxygen-tolerant spore form to transmit disease. However, the molecular mechanisms by which those spores germinate to initiate infection and then form new spores to transmit infection remain poorly understood. While sporulation and germination have been well characterized in Bacillus subtilis and Bacillus anthracis, striking differences in the regulation of these processes have been observed between the bacilli and the clostridia, with even some conserved proteins exhibiting differences in their requirements and functions. Here, we review our current understanding of how clostridial pathogens, specifically Clostridium perfringens, Clostridium botulinum, and Clostridioides difficile, induce sporulation in response to environmental cues, assemble resistant spores, and germinate metabolically dormant spores in response to environmental cues. We also discuss the direct relationship between toxin production and spore formation in these pathogens.
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Affiliation(s)
- Aimee Shen
- Department of Molecular Biology and Microbiology, Tufts University Medical School, Boston, MA
| | - Adrianne N Edwards
- Department of Microbiology and Immunology, Emory University School of Medicine, Atlanta, GA
| | - Mahfuzur R Sarker
- Department of Microbiology, College of Science, Oregon State University, Corvallis, OR
- Department of Biomedical Sciences, College of Veterinary Medicine, Oregon State University, Corvallis, OR
| | - Daniel Paredes-Sabja
- Department of Gut Microbiota and Clostridia Research Group, Departamento de Ciencias Biolo gicas, Facultad de Ciencias Biologicas, Universidad Andres Bello, Santiago, Chile
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Phase variation of a signal transduction system controls Clostridioides difficile colony morphology, motility, and virulence. PLoS Biol 2019; 17:e3000379. [PMID: 31658249 PMCID: PMC6837544 DOI: 10.1371/journal.pbio.3000379] [Citation(s) in RCA: 32] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2019] [Revised: 11/07/2019] [Accepted: 10/15/2019] [Indexed: 12/20/2022] Open
Abstract
Recent work has revealed that Clostridioides difficile, a major cause of nosocomial diarrheal disease, exhibits phenotypic heterogeneity within a clonal population as a result of phase variation. Many C. difficile strains representing multiple ribotypes develop two colony morphotypes, termed rough and smooth, but the biological implications of this phenomenon have not been explored. Here, we examine the molecular basis and physiological relevance of the distinct colony morphotypes produced by this bacterium. We show that C. difficile reversibly differentiates into rough and smooth colony morphologies and that bacteria derived from the isolates display discrete motility behaviors. We identified an atypical phase-variable signal transduction system consisting of a histidine kinase and two response regulators, named herein colony morphology regulators RST (CmrRST), which mediates the switch in colony morphology and motility behaviors. The CmrRST-regulated surface motility is independent of flagella and type IV pili, suggesting a novel mechanism of cell migration in C. difficile. Microscopic analysis of cell and colony structure indicates that CmrRST promotes the formation of elongated bacteria arranged in bundled chains, which may contribute to bacterial migration on surfaces. In a hamster model of acute C. difficile disease, the CmrRST system is required for disease development. Furthermore, we provide evidence that CmrRST phase varies during infection, suggesting that the intestinal environment impacts the proportion of CmrRST-expressing C. difficile. Our findings indicate that C. difficile employs phase variation of the CmrRST signal transduction system to generate phenotypic heterogeneity during infection, with concomitant effects on bacterial physiology and pathogenesis. In many bacterial species, a genetically clonal population can generate phenotypic heterogeneity to ensure survival of a subpopulation in the face of sudden environmental stressors. This work shows that the intestinal pathogen Clostridioides difficile introduces heterogeneity into the population through the phase-variable expression of a signal transduction system, resulting in broad changes in physiology, motility, and virulence.
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Ciftci Y, Girinathan BP, Dhungel BA, Hasan MK, Govind R. Clostridioides difficile SinR' regulates toxin, sporulation and motility through protein-protein interaction with SinR. Anaerobe 2019; 59:1-7. [PMID: 31077800 PMCID: PMC6785386 DOI: 10.1016/j.anaerobe.2019.05.002] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2018] [Revised: 04/10/2019] [Accepted: 05/07/2019] [Indexed: 12/18/2022]
Abstract
Clostridioides difficile is a Gram-positive, anaerobic bacterium. It is known that C. difficile is one of the major causes of antibiotic associated diarrhea. The enhanced antibiotic resistance observed in C. difficile is the result of highly resistant spores produced by the bacterium. In Bacillus subtilis, the sin operon is involved in sporulation inhibition. Two proteins coded within this operon, SinR and SinI, have an antagonistic relationship; SinR acts as an inhibitor to sporulation whereas SinI represses the activity of SinR, thus allowing the bacterium to sporulate. In a previous study, we examined the sin locus in C. difficile and named the two genes associated with this operon sinR and sinR', analogous to sinR and sinI in B. subtilis, respectively. We have shown that SinR and SinR' have pleiotropic roles in pathogenesis pathways and interact antagonistically with each other. Unlike B. subtilis SinI, SinR' in C. difficile carries two domains: the HTH domain and the Multimerization Domain (MD). In this study, we first performed a GST Pull-down experiment to determine the domain within SinR' that interacts with SinR. Second, the effect of these two domains on three phenotypes; sporulation, motility, and toxin production was examined. The findings of this study confirmed the prediction that the Multimerization Domain (MD) of SinR' is responsible for the interaction between SinR and SinR'. It was also discovered that SinR' regulates sporulation, toxin production and motility primarily by inhibiting SinR activity through the Multimerization Domain (MD).
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Affiliation(s)
- Yusuf Ciftci
- Division of Biology, Kansas State University, Manhattan, KS, USA
| | - Brintha Parasumanna Girinathan
- Division of Biology, Kansas State University, Manhattan, KS, USA; Department of Pathology, Harvard Medical School, Boston, MA, USA
| | | | - Md Kamrul Hasan
- Division of Biology, Kansas State University, Manhattan, KS, USA
| | - Revathi Govind
- Division of Biology, Kansas State University, Manhattan, KS, USA.
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Mileto S, Das A, Lyras D. Enterotoxic Clostridia: Clostridioides difficile Infections. Microbiol Spectr 2019; 7:10.1128/microbiolspec.gpp3-0015-2018. [PMID: 31124432 PMCID: PMC11026080 DOI: 10.1128/microbiolspec.gpp3-0015-2018] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2018] [Indexed: 12/17/2022] Open
Abstract
Clostridioides difficile is a Gram-positive, anaerobic, spore forming pathogen of both humans and animals and is the most common identifiable infectious agent of nosocomial antibiotic-associated diarrhea. Infection can occur following the ingestion and germination of spores, often concurrently with a disruption to the gastrointestinal microbiota, with the resulting disease presenting as a spectrum, ranging from mild and self-limiting diarrhea to severe diarrhea that may progress to life-threating syndromes that include toxic megacolon and pseudomembranous colitis. Disease is induced through the activity of the C. difficile toxins TcdA and TcdB, both of which disrupt the Rho family of GTPases in host cells, causing cell rounding and death and leading to fluid loss and diarrhea. These toxins, despite their functional and structural similarity, do not contribute to disease equally. C. difficile infection (CDI) is made more complex by a high level of strain diversity and the emergence of epidemic strains, including ribotype 027-strains which induce more severe disease in patients. With the changing epidemiology of CDI, our understanding of C. difficile disease, diagnosis, and pathogenesis continues to evolve. This article provides an overview of the current diagnostic tests available for CDI, strain typing, the major toxins C. difficile produces and their mode of action, the host immune response to each toxin and during infection, animal models of disease, and the current treatment and prevention strategies for CDI.
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Affiliation(s)
- S Mileto
- Infection and Immunity Program, Monash Biomedicine Discovery Institute and Department of Microbiology, Monash University, Clayton, Victoria, Australia, 3800
| | - A Das
- Infection and Immunity Program, Monash Biomedicine Discovery Institute and Department of Microbiology, Monash University, Clayton, Victoria, Australia, 3800
| | - D Lyras
- Infection and Immunity Program, Monash Biomedicine Discovery Institute and Department of Microbiology, Monash University, Clayton, Victoria, Australia, 3800
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Arato V, Gasperini G, Giusti F, Ferlenghi I, Scarselli M, Leuzzi R. Dual role of the colonization factor CD2831 in Clostridium difficile pathogenesis. Sci Rep 2019; 9:5554. [PMID: 30944377 PMCID: PMC6447587 DOI: 10.1038/s41598-019-42000-8] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2018] [Accepted: 03/12/2019] [Indexed: 01/01/2023] Open
Abstract
Clostridium difficile is a Gram-positive, anaerobic bacterium and the leading cause of antibiotic-associated diarrhea and pseudomembranous colitis. C. difficile modulates its transition from a motile to a sessile lifestyle through a mechanism of riboswitches regulated by cyclic diguanosine monophosphate (c-di-GMP). Previously described as a sortase substrate positively regulated by c-di-GMP, CD2831 was predicted to be a collagen-binding protein and thus potentially involved in sessility. By overexpressing CD2831 in C. difficile and heterologously expressing it on the surface of Lactococcus lactis, here we further demonstrated that CD2831 is a collagen-binding protein, able to bind to immobilized collagen types I, III and V as well as native collagen produced by human fibroblasts. We also observed that the overexpression of CD2831 raises the ability to form biofilm on abiotic surface in both C. difficile and L. lactis. Notably, we showed that CD2831 binds to the collagen-like domain of the human complement component C1q, suggesting a role in preventing complement cascade activation via the classical pathway. This functional characterization places CD2831 in the Microbial Surface Components Recognizing Adhesive Matrix Molecule (MSCRAMMs) family, a class of virulence factors with a dual role in adhesion to collagen-rich tissues and in host immune evasion by binding to human complement components.
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Affiliation(s)
- Vanessa Arato
- Glaxo Smith Kline Vaccines, Via Fiorentina 1, 53100, Siena, Italy.,University of Padova, Department of Biomedical Sciences, 35131, Padua, Italy
| | - Gianmarco Gasperini
- GSK Vaccines Institute for Global Health (GVGH), Via Fiorentina 1, 53100, Siena, Italy
| | - Fabiola Giusti
- Glaxo Smith Kline Vaccines, Via Fiorentina 1, 53100, Siena, Italy
| | - Ilaria Ferlenghi
- Glaxo Smith Kline Vaccines, Via Fiorentina 1, 53100, Siena, Italy
| | - Maria Scarselli
- Glaxo Smith Kline Vaccines, Via Fiorentina 1, 53100, Siena, Italy
| | - Rosanna Leuzzi
- Glaxo Smith Kline Vaccines, Via Fiorentina 1, 53100, Siena, Italy.
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Edwards AN, Anjuwon-Foster BR, McBride SM. RstA Is a Major Regulator of Clostridioides difficile Toxin Production and Motility. mBio 2019; 10:e01991-18. [PMID: 30862746 PMCID: PMC6414698 DOI: 10.1128/mbio.01991-18] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2018] [Accepted: 01/25/2019] [Indexed: 01/05/2023] Open
Abstract
Clostridioides difficile infection (CDI) is a toxin-mediated diarrheal disease. Several factors have been identified that influence the production of the two major C. difficile toxins, TcdA and TcdB, but prior published evidence suggested that additional unknown factors were involved in toxin regulation. Previously, we identified a C. difficile regulator, RstA, that promotes sporulation and represses motility and toxin production. We observed that the predicted DNA-binding domain of RstA was required for RstA-dependent repression of toxin genes, motility genes, and rstA transcription. In this study, we further investigated the regulation of toxin and motility gene expression by RstA. DNA pulldown assays confirmed that RstA directly binds the rstA promoter via the predicted DNA-binding domain. Through mutational analysis of the rstA promoter, we identified several nucleotides that are important for RstA-dependent transcriptional regulation. Further, we observed that RstA directly binds and regulates the promoters of the toxin genes tcdA and tcdB, as well as the promoters for the sigD and tcdR genes, which encode regulators of toxin gene expression. Complementation analyses with the Clostridium perfringens RstA ortholog and a multispecies chimeric RstA protein revealed that the C. difficile C-terminal domain is required for RstA DNA-binding activity, suggesting that species-specific signaling controls RstA function. Our data demonstrate that RstA is a transcriptional repressor that autoregulates its own expression and directly inhibits transcription of the two toxin genes and two positive toxin regulators, thereby acting at multiple regulatory points to control toxin production.IMPORTANCEClostridioides difficile is an anaerobic, gastrointestinal pathogen of humans and other mammals. C. difficile produces two major toxins, TcdA and TcdB, which cause the symptoms of the disease, and forms dormant endospores to survive the aerobic environment outside the host. A recently discovered regulatory factor, RstA, inhibits toxin production and positively influences spore formation. Herein, we determine that RstA directly binds its own promoter DNA to repress its own gene transcription. In addition, our data demonstrate that RstA directly represses toxin gene expression and gene expression of two toxin gene activators, TcdR and SigD, creating a complex regulatory network to tightly control toxin production. This study provides a novel regulatory link between C. difficile sporulation and toxin production. Further, our data suggest that C. difficile toxin production is regulated through a direct, species-specific sensing mechanism.
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Affiliation(s)
- Adrianne N Edwards
- Department of Microbiology and Immunology, Emory Antibiotic Resistance Center, Emory University School of Medicine, Atlanta, Georgia, USA
| | - Brandon R Anjuwon-Foster
- Department of Microbiology and Immunology, University of North Carolina at Chapel Hill School of Medicine, Chapel Hill, North Carolina, USA
| | - Shonna M McBride
- Department of Microbiology and Immunology, Emory Antibiotic Resistance Center, Emory University School of Medicine, Atlanta, Georgia, USA
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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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48
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Ransom EM, Kaus GM, Tran PM, Ellermeier CD, Weiss DS. Multiple factors contribute to bimodal toxin gene expression in Clostridioides (Clostridium) difficile. Mol Microbiol 2018; 110:533-549. [PMID: 30125399 PMCID: PMC6446242 DOI: 10.1111/mmi.14107] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2018] [Revised: 08/10/2018] [Accepted: 08/11/2018] [Indexed: 12/14/2022]
Abstract
Clostridioides (formerly Clostridium) difficile produces two major toxins, TcdA and TcdB, upon entry into stationary phase. Transcription of tcdA and tcdB requires the specialized sigma factor, σTcdR , which also directs RNA Polymerase to transcribe tcdR itself. We fused a gene for a red fluorescent protein to the tcdA promoter to study toxin gene expression at the level of individual C. difficile cells. Surprisingly, only a subset of cells became red fluorescent upon entry into stationary phase. Breaking the positive feedback loop that controls σTcdR production by engineering cells to express tcdR from a tetracycline-inducible promoter resulted in uniform fluorescence across the population. Experiments with two regulators of tcdR expression, σD and CodY, revealed neither is required for bimodal toxin gene expression. However, σD biased cells toward the Toxin-ON state, while CodY biased cells toward the Toxin-OFF state. Finally, toxin gene expression was observed in sporulating cells. We conclude that (i) toxin production is regulated by a bistable switch governed by σTcdR , which only accumulates to high enough levels to trigger toxin gene expression in a subset of cells, and (ii) toxin production and sporulation are not mutually exclusive developmental programs.
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Affiliation(s)
- Eric M. Ransom
- Department of Microbiology and Immunology, Carver College of Medicine, University of Iowa, Iowa City, IA 52242
| | - Gabriela M. Kaus
- Department of Microbiology and Immunology, Carver College of Medicine, University of Iowa, Iowa City, IA 52242
| | - Phuong M. Tran
- Department of Microbiology and Immunology, Carver College of Medicine, University of Iowa, Iowa City, IA 52242
| | - Craig D. Ellermeier
- Department of Microbiology and Immunology, Carver College of Medicine, University of Iowa, Iowa City, IA 52242
- Graduate Program in Genetics, University of Iowa, Iowa City, IA 52242
| | - David S. Weiss
- Department of Microbiology and Immunology, Carver College of Medicine, University of Iowa, Iowa City, IA 52242
- Graduate Program in Genetics, University of Iowa, Iowa City, IA 52242
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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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Gu H, Shi K, Liao Z, Qi H, Chen S, Wang H, Li S, Ma Y, Wang J. Time-resolved transcriptome analysis of Clostridium difficile R20291 response to cysteine. Microbiol Res 2018; 215:114-125. [PMID: 30172297 DOI: 10.1016/j.micres.2018.07.003] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2018] [Revised: 05/21/2018] [Accepted: 07/07/2018] [Indexed: 01/05/2023]
Abstract
The incidence of Clostridium difficile infection has been steadily rising over the past decade. The increase in the rate of incidence is associated with the specific NAP1/BI/027 strains which are "hypervirulent" and have led to several large outbreaks since their emergence. However, the relation between these outbreaks and virulence regulation mechanisms remains unclear. It has been reported that the major virulence factor TcdA and TcdB in C. difficile could be repressed by cysteine. Here, we investigated the functional and virulence-associated regulation of C. difficile R20291 response to cysteine by using a time-resolved genome-wide transcriptome analysis. Dramatic changes of gene expression in C. difficile revealed functional processes related to transport, metabolism, and regulators in the presence of cysteine during different phases of growth. Flagellar and ribosomal genes were significantly down-regulated in long-term response to cysteine. Many NAP1/BI/027- specific genes were also modulated by cysteine. In addition, cdsB inactivation in C. difficile R20291 could remove the repression of toxin synthesis but could not remove the repression of butyrate production in the presence of cysteine. This suggests that toxin synthesis and butyrate production might have different regulatory controls in response to cysteine. Altogether, our research provides important insights into the regulatory mechanisms of C. difficile response to cysteine.
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Affiliation(s)
- Huawei Gu
- School of Biology and Biological Engineering, South China University of Technology, Guangzhou, China
| | - Kan Shi
- School of Biology and Biological Engineering, South China University of Technology, Guangzhou, China
| | - Zhengping Liao
- School of Biology and Biological Engineering, South China University of Technology, Guangzhou, China
| | - Haonan Qi
- School of Biology and Biological Engineering, South China University of Technology, Guangzhou, China
| | - Shuyi Chen
- School of Biology and Biological Engineering, South China University of Technology, Guangzhou, China
| | - Haiying Wang
- School of Biology and Biological Engineering, South China University of Technology, Guangzhou, China
| | - Shan Li
- School of Biology and Biological Engineering, South China University of Technology, Guangzhou, China
| | - Yi Ma
- School of Biology and Biological Engineering, South China University of Technology, Guangzhou, China
| | - Jufang Wang
- School of Biology and Biological Engineering, South China University of Technology, Guangzhou, China.
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