1
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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] [MESH Headings] [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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Cassona CP, Ramalhete S, Amara K, Candela T, Kansau I, Denève-Larrazet C, Janoir-Jouveshomme C, Mota LJ, Dupuy B, Serrano M, Henriques AO. Spores of Clostridioides difficile are toxin delivery vehicles. Commun Biol 2024; 7:839. [PMID: 38987278 PMCID: PMC11237016 DOI: 10.1038/s42003-024-06521-x] [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: 05/08/2023] [Accepted: 06/28/2024] [Indexed: 07/12/2024] Open
Abstract
Clostridioides difficile causes a wide range of intestinal diseases through the action of two main cytotoxins, TcdA and TcdB. Ingested spores germinate in the intestine establishing a population of cells that produce toxins and spores. The pathogenicity locus, PaLoc, comprises several genes, including those coding for TcdA/B, for the holin-like TcdE protein, and for TcdR, an auto-regulatory RNA polymerase sigma factor essential for tcdA/B and tcdE expression. Here we show that tcdR, tcdA, tcdB and tcdE are expressed in a fraction of the sporulating cells, in either the whole sporangium or in the forespore. The whole sporangium pattern is due to protracted expression initiated in vegetative cells by σD, which primes the TcdR auto-regulatory loop. In contrast, the forespore-specific regulatory proteins σG and SpoVT control TcdR production and tcdA/tcdB and tcdE expression in this cell. We detected TcdA at the spore surface, and we show that wild type and ΔtcdA or ΔtcdB spores but not ΔtcdR or ΔtcdA/ΔtcdB spores are cytopathic against HT29 and Vero cells, indicating that spores may serve as toxin-delivery vehicles. Since the addition of TcdA and TcdB enhance binding of spores to epithelial cells, this effect may occur independently of toxin production by vegetative cells.
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Affiliation(s)
- Carolina P Cassona
- Instituto de Tecnologia Química e Biológica, NOVA University Lisbon, Oeiras, Portugal
| | - Sara Ramalhete
- Instituto de Tecnologia Química e Biológica, NOVA University Lisbon, Oeiras, Portugal
| | - Khira Amara
- Instituto de Tecnologia Química e Biológica, NOVA University Lisbon, Oeiras, Portugal
| | - Thomas Candela
- Micalis Institute, Université Paris-Saclay, INRAE, AgroParisTech, Jouy-en-Josas, France
| | - Imad Kansau
- Micalis Institute, Université Paris-Saclay, INRAE, AgroParisTech, Jouy-en-Josas, France
| | | | | | - Luís Jaime Mota
- Associate Laboratory i4HB, Institute for Health and Bioeconomy, NOVA School of Science and Technology, NOVA University Lisbon, Caparica, Portugal
- UCIBIO, Applied Molecular Biosciences Unit, Department of Life Sciences, NOVA School of Science and Technology, NOVA University Lisbon, Caparica, Portugal
| | - Bruno Dupuy
- Institut Pasteur, Université Paris-Cité, UMR-CNRS 6047, Laboratoire Pathogenèse des Bactéries Anaérobies, F-75015, Paris, France
| | - Mónica Serrano
- Instituto de Tecnologia Química e Biológica, NOVA University Lisbon, Oeiras, Portugal
| | - Adriano O Henriques
- Instituto de Tecnologia Química e Biológica, NOVA University Lisbon, Oeiras, Portugal.
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3
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BELITSKY BORISR. Histidine kinase-mediated cross-regulation of the vancomycin-resistance operon in Clostridioides difficile. Mol Microbiol 2024; 121:1182-1199. [PMID: 38690761 PMCID: PMC11176017 DOI: 10.1111/mmi.15273] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2024] [Revised: 04/03/2024] [Accepted: 04/17/2024] [Indexed: 05/03/2024]
Abstract
The dipeptide D-Ala-D-Ala is an essential component of peptidoglycan and the target of vancomycin. Most Clostridioides difficile strains possess the vanG operon responsible for the synthesis of D-Ala-D-Ser, which can replace D-Ala-D-Ala in peptidoglycan. The C. difficile vanG operon is regulated by a two-component system, VanRS, but is not induced sufficiently by vancomycin to confer resistance to this antibiotic. Surprisingly, in the absence of the VanS histidine kinase (HK), the vanG operon is still induced by vancomycin and also by another antibiotic, ramoplanin, in a VanR-dependent manner. This suggested the cross-regulation of VanR by another HK or kinases that are activated in the presence of certain lipid II-targeting antibiotics. We identified these HKs as CD35990 and CD22880. However, mutations in either or both HKs did not affect the regulation of the vanG operon in wild-type cells suggesting that intact VanS prevents the cross-activation of VanR by non-cognate HKs. Overproduction of VanR in the absence of VanS, CD35990, and CD22880 led to high expression of the vanG operon indicating that VanR can potentially utilize at least one more phosphate donor for its activation. Candidate targets of CD35990- and CD22880-mediated regulation in the presence of vancomycin or ramoplanin were identified by RNA-Seq.
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Affiliation(s)
- BORIS R. BELITSKY
- Department of Molecular Biology and Microbiology, Tufts University School of Medicine, Boston, Massachusetts 02111, USA
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4
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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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Mehdizadeh Gohari I, Gonzales JL, Uzal FA, McClane BA. Overexpressing the cpr1953 Orphan Histidine Kinase Gene in the Absence of cpr1954 Orphan Histidine Kinase Gene Expression, or Vice Versa, Is Sufficient to Obtain Significant Sporulation and Strong Production of Clostridium perfringens Enterotoxin or Spo0A by Clostridium perfringens Type F Strain SM101. Toxins (Basel) 2024; 16:195. [PMID: 38668620 PMCID: PMC11053440 DOI: 10.3390/toxins16040195] [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: 03/13/2024] [Revised: 04/03/2024] [Accepted: 04/10/2024] [Indexed: 04/29/2024] Open
Abstract
The CPR1953 and CPR1954 orphan histidine kinases profoundly affect sporulation initiation and Clostridium perfringens enterotoxin (CPE) production by C. perfringens type F strain SM101, whether cultured in vitro (modified Duncan-Strong sporulation medium (MDS)) or ex vivo (mouse small intestinal contents (MIC)). To help distinguish whether CPR1953 and CPR1954 act independently or in a stepwise manner to initiate sporulation and CPE production, cpr1953 and cpr1954 null mutants of SM101 were transformed with plasmids carrying the cpr1954 or cpr1953 genes, respectively, causing overexpression of cpr1954 in the absence of cpr1953 expression and vice versa. RT-PCR confirmed that, compared to SM101, the cpr1953 mutant transformed with a plasmid encoding cpr1954 expressed cpr1954 at higher levels while the cpr1954 mutant transformed with a plasmid encoding cpr1953 expressed higher levels of cpr1953. Both overexpressing strains showed near wild-type levels of sporulation, CPE toxin production, and Spo0A production in MDS or MIC. These findings suggest that CPR1953 and CPR1954 do not function together in a step-wise manner, e.g., as a novel phosphorelay. Instead, it appears that, at natural expression levels, the independent kinase activities of both CPR1953 and CPR1954 are necessary for obtaining sufficient Spo0A production and phosphorylation to initiate sporulation and CPE production.
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Affiliation(s)
- Iman Mehdizadeh Gohari
- Department of Microbiology and Molecular Genetics, University of Pittsburgh School of Medicine, Pittsburgh, PA 15219, USA;
| | - Jessica L. Gonzales
- California Animal Health and Food Safety Laboratory System, School of Veterinary Medicine, University of California Davis, San Bernardino, CA 92408, USA; (J.L.G.); (F.A.U.)
| | - Francisco A. Uzal
- California Animal Health and Food Safety Laboratory System, School of Veterinary Medicine, University of California Davis, San Bernardino, CA 92408, USA; (J.L.G.); (F.A.U.)
| | - Bruce A. McClane
- Department of Microbiology and Molecular Genetics, University of Pittsburgh School of Medicine, Pittsburgh, PA 15219, USA;
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6
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Mehdizadeh Gohari I, Edwards AN, McBride SM, McClane BA. The impact of orphan histidine kinases and phosphotransfer proteins on the regulation of clostridial sporulation initiation. mBio 2024; 15:e0224823. [PMID: 38477571 PMCID: PMC11210211 DOI: 10.1128/mbio.02248-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/14/2024] Open
Abstract
Sporulation is an important feature of the clostridial life cycle, facilitating survival of these bacteria in harsh environments, contributing to disease transmission for pathogenic species, and sharing common early steps that are also involved in regulating industrially important solvent production by some non-pathogenic species. Initial genomics studies suggested that Clostridia lack the classical phosphorelay that phosphorylates Spo0A and initiates sporulation in Bacillus, leading to the hypothesis that sporulation in Clostridia universally begins when Spo0A is phosphorylated by orphan histidine kinases (OHKs). However, components of the classical Bacillus phosphorelay were recently identified in some Clostridia. Similar Bacillus phosphorelay components have not yet been found in the pathogenic Clostridia or the solventogenic Clostridia of industrial importance. For some of those Clostridia lacking a classical phosphorelay, the involvement of OHKs in sporulation initiation has received support from genetic studies demonstrating the involvement of several apparent OHKs in their sporulation. In addition, several clostridial OHKs directly phosphorylate Spo0A in vitro. Interestingly, there is considerable protein domain diversity among the sporulation-associated OHKs in Clostridia. Further adding to the emergent complexity of sporulation initiation in Clostridia, several candidate OHK phosphotransfer proteins that were OHK candidates were shown to function as phosphatases that reduce sporulation in some Clostridia. The mounting evidence indicates that no single pathway explains sporulation initiation in all Clostridia and supports the need for further study to fully understand the unexpected and biologically fascinating mechanistic diversity of this important process among these medically and industrially important bacteria.
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Affiliation(s)
- Iman Mehdizadeh Gohari
- Department of Microbiology and Molecular Genetics, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, USA
| | - Adrianne N. Edwards
- Department of Microbiology and Immunology, Emory University School of Medicine, Emory Antibiotic Resistance Center, Atlanta, Georgia, USA
| | - Shonna M. McBride
- Department of Microbiology and Immunology, Emory University School of Medicine, Emory Antibiotic Resistance Center, Atlanta, Georgia, USA
| | - Bruce A. McClane
- Department of Microbiology and Molecular Genetics, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, USA
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7
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Hu C, Garey KW. Microscopy methods for Clostridioides difficile. Anaerobe 2024; 86:102822. [PMID: 38341023 DOI: 10.1016/j.anaerobe.2024.102822] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2023] [Revised: 01/25/2024] [Accepted: 01/29/2024] [Indexed: 02/12/2024]
Abstract
Microscopic technologies including light and fluorescent, transmission electron microscopy (TEM), scanning electron microscopy (SEM), and cryo-electron microscopy have been widely utilized to visualize Clostridioides difficile at the molecular, cellular, community, and structural biology level. This comprehensive review summarizes the microscopy tools (fluorescent and reporter system) in their use to study different aspects of C. difficile life cycle and virulence (sporulation, germination) or applications (detection of C. difficile or use of antimicrobials). With these developing techniques, microscopy tools will be able to find broader applications and address more challenging questions to study C. difficile and C. difficile infection.
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Affiliation(s)
- Chenlin Hu
- University of Houston College of Pharmacy, Houston, TX, USA
| | - Kevin W Garey
- University of Houston College of Pharmacy, Houston, TX, USA.
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8
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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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9
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Serrano M, Martins D, Henriques AO. Clostridioides difficile Sporulation. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2024; 1435:273-314. [PMID: 38175480 DOI: 10.1007/978-3-031-42108-2_13] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/05/2024]
Abstract
Some members of the Firmicutes phylum, including many members of the human gut microbiota, are able to differentiate a dormant and highly resistant cell type, the endospore (hereinafter spore for simplicity). Spore-formers can colonize virtually any habitat and, because of their resistance to a wide variety of physical and chemical insults, spores can remain viable in the environment for long periods of time. In the anaerobic enteric pathogen Clostridioides difficile the aetiologic agent is the oxygen-resistant spore, while the toxins produced by actively growing cells are the main cause of the disease symptoms. Here, we review the regulatory circuits that govern entry into sporulation. We also cover the role of spores in the infectious cycle of C. difficile in relation to spore structure and function and the main control points along spore morphogenesis.
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Affiliation(s)
- Mónica Serrano
- Instituto de Tecnologia Química e Biológica António Xavier, Oeiras, Portugal.
| | - Diogo Martins
- Instituto de Tecnologia Química e Biológica António Xavier, Oeiras, Portugal
| | - Adriano O Henriques
- Instituto de Tecnologia Química e Biológica António Xavier, Oeiras, Portugal
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10
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Leong SS, Korel F, King JH. Bacillus cereus: A review of "fried rice syndrome" causative agents. Microb Pathog 2023; 185:106418. [PMID: 37866551 DOI: 10.1016/j.micpath.2023.106418] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2023] [Revised: 10/19/2023] [Accepted: 10/19/2023] [Indexed: 10/24/2023]
Abstract
"Fried rice syndrome" originated from the first exposure to a fried rice dish contaminated with Bacillus cereus. This review compiles available data on the prevalence of B. cereus outbreak cases that occurred between 1984 and 2019. The outcome of B. cereus illness varies dramatically depending on the pathogenic strain encounter and the host's immune system. B. cereus causes a self-limiting, diarrheal illness caused by heat-resistant enterotoxin proteins, and an emetic illness caused by the deadly toxin named cereulide. The toxins together with their extrinsic factors are discussed. The possibility of more contamination of B. cereus in protein-rich food has also been shown. Therefore, the aim of this review is to summarize the available data, focusing mainly on B. cereus physiology as the causative agent for "fried rice syndrome." This review emphasizes the prevalence of B. cereus in starchy food contamination and outbreak cases reported, the virulence of both enterotoxins and emetic toxins produced, and the possibility of contaminated in protein-rich food. The impact of emetic or enterotoxin-producing B. cereus on public health cannot be neglected. Thus, it is essential to constantly monitor for B. cereus contamination during food handling and hygiene practices for food product preparation.
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Affiliation(s)
- Sui Sien Leong
- Department of Animal Sciences and Fishery, Faculty of Agricultural and Forestry Sciences, Universiti Putra Malaysia, Nyabau Road, Bintulu, 97008, Sarawak, Malaysia; Institute of Ecosystem Science Borneo, Universiti Putra Malaysia Bintulu Sarawak Campus, Nyabau Road, Bintulu, 97008, Sarawak, Malaysia.
| | - Figen Korel
- Food Engineering Department, Faculty of Engineering, Izmir Institute of Technology, Urla, 35430, İzmir, Turkey
| | - Jie Hung King
- Department of Crop Science, Faculty of Agricultural and Forestry Sciences, Universiti Putra Malaysia, Nyabau Road, Bintulu, 97008, Sarawak, Malaysia
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11
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Pal R, Seleem MN. Antisense inhibition of RNA polymerase α subunit of Clostridioides difficile. Microbiol Spectr 2023; 11:e0175523. [PMID: 37772833 PMCID: PMC10581251 DOI: 10.1128/spectrum.01755-23] [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: 04/26/2023] [Accepted: 08/14/2023] [Indexed: 09/30/2023] Open
Abstract
Clostridioides difficile, the causative agent of antibiotic-associated diarrhea and pseudomembranous colitis, has emerged as a major enteric pathogen in recent years. Antibiotic treatment perturbs the gut microbiome homeostasis, which facilitates the colonization and proliferation of the pathogen in the host intestine. Paradoxically, the clinical repertoire for C. difficile infection includes the antibiotics vancomycin and/or fidaxomicin. The current therapies do not address the perturbed gut microbiome, which supports the recurrence of infection after cessation of antibiotic therapy. Peptide nucleic acids (PNAs) are novel alternatives to traditional antimicrobial therapy capable of forming strong and stable complexes with RNA and DNA, thus permitting targeted inhibition of specific genes. Here, we report a novel PNA that can target the RNA polymerase α subunit (rpoA) in C. difficile. The designed anti-rpoA construct inhibited clinical isolates of C. difficile (minimum inhibitory concentration values ranged between 4 and 8 µM) and exhibited bactericidal activity. Furthermore, silencing of the rpoA gene suppressed the expression of genes that encode virulence factors [toxin A (tcdA), toxin B (tcdB)] in C. difficile, and the gene that encodes the transcription factor stage 0 sporulation protein (spoOA). Interestingly, the efficacy of the designed PNA conjugate remained unaffected even when tested at different pH levels and against a high inoculum of the pathogen. The rpoA-TAT conjugate was very specific against C. difficile and did not inhibit members of the beneficial gut microflora. Taken altogether, our study confirms that the rpoA gene can be a promising narrow-spectrum therapeutic target to curb C. difficile infection. IMPORTANCE The widespread use of antibiotics can destroy beneficial intestinal microflora, opening the door for spores of Clostridioides difficile to run rampant in the digestive system, causing life-threatening diarrhea. Alternative approaches to target this deadly pathogen are urgently needed. We utilized targeted therapeutics called peptide nucleic acids (PNAs) to inhibit gene expression in C. difficile. Inhibition of the RNA polymerase α subunit gene (rpoA) by PNA was found to be lethal for C. difficile and could also disarm its virulence factors. Additionally, antisense inhibition of the C. difficile rpoA gene did not impact healthy microflora. We also propose a novel approach to manipulate gene expression in C. difficile without the need for established genetic tools.
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Affiliation(s)
- Rusha Pal
- Department of Biomedical Sciences and Pathobiology, Virginia-Maryland College of Veterinary Medicine, Virginia Polytechnic Institute and State University, Blacksburg, Virginia, USA
| | - Mohamed N. Seleem
- Department of Biomedical Sciences and Pathobiology, Virginia-Maryland College of Veterinary Medicine, Virginia Polytechnic Institute and State University, Blacksburg, Virginia, USA
- Center for Emerging Zoonotic and Arthropod-borne Pathogens, Virginia Polytechnic Institute and State University, Blacksburg, Virginia, USA
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12
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Mehdizadeh Gohari I, Li J, Navarro MA, Mendonça FS, Uzal FA, McClane BA. Identification of orphan histidine kinases that impact sporulation and enterotoxin production by Clostridium perfringens type F strain SM101 in a pathophysiologically-relevant ex vivo mouse intestinal contents model. PLoS Pathog 2023; 19:e1011429. [PMID: 37262083 PMCID: PMC10263361 DOI: 10.1371/journal.ppat.1011429] [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: 11/22/2022] [Revised: 06/13/2023] [Accepted: 05/17/2023] [Indexed: 06/03/2023] Open
Abstract
When causing food poisoning or antibiotic-associated diarrhea, Clostridium perfringens type F strains must sporulate to produce C. perfringens enterotoxin (CPE) in the intestines. C. perfringens is thought to use some of its seven annotated orphan histidine kinases to phosphorylate Spo0A and initiate sporulation and CPE production. We previously demonstrated the CPR0195 orphan kinase, but not the putative CPR1055 orphan kinase, is important when type F strain SM101 initiates sporulation and CPE production in modified Duncan-Strong (MDS) sporulation medium. Since there is no small animal model for C. perfringens sporulation, the current study used diluted mouse intestinal contents (MIC) to develop an ex vivo sporulation model and employed this model to test sporulation and CPE production by SM101 CPR0195 and CPR1055 null mutants in a pathophysiologically-relevant context. Surprisingly, both mutants still sporulated and produced CPE at wild-type levels in MIC. Therefore, five single null mutants were constructed that cannot produce one of the previously-unstudied putative orphan kinases of SM101. Those mutants implicated CPR1316, CPR1493, CPR1953 and CPR1954 in sporulation and CPE production by SM101 MDS cultures. Phosphorylation activity was necessary for CPR1316, CPR1493, CPR1953 and CPR1954 to affect sporulation in those MDS cultures, supporting their identity as kinases. Importantly, only the CPR1953 or CPR1954 null mutants exhibited significantly reduced levels of sporulation and CPE production in MIC cultures. These phenotypes were reversible by complementation. Characterization studies suggested that, in MDS or MIC, the CPR1953 and CPR1954 mutants produce less Spo0A than wild-type SM101. In addition, the CPR1954 mutant exhibited little or no Spo0A phosphorylation in MDS cultures. These studies, i) highlight the importance of using pathophysiologically-relevant models to investigate C. perfringens sporulation and CPE production in a disease context and ii) link the CPR1953 and CPR1954 kinases to C. perfringens sporulation and CPE production in disease-relevant conditions.
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Affiliation(s)
- Iman Mehdizadeh Gohari
- Department of Microbiology and Molecular Genetics, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, United States of America
| | - Jihong Li
- Department of Microbiology and Molecular Genetics, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, United States of America
| | - Mauricio A. Navarro
- California Animal Health and Food Safety Laboratory System, School of Veterinary Medicine, University of California Davis, San Bernardino, California, United States of America
| | - Fábio S. Mendonça
- California Animal Health and Food Safety Laboratory System, School of Veterinary Medicine, University of California Davis, San Bernardino, California, United States of America
| | - Francisco A. Uzal
- California Animal Health and Food Safety Laboratory System, School of Veterinary Medicine, University of California Davis, San Bernardino, California, United States of America
| | - Bruce A. McClane
- Department of Microbiology and Molecular Genetics, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, United States of America
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13
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Fuchs M, Lamm-Schmidt V, Lenče T, Sulzer J, Bublitz A, Wackenreuter J, Gerovac M, Strowig T, Faber F. A network of small RNAs regulates sporulation initiation in Clostridioides difficile. EMBO J 2023:e112858. [PMID: 37140366 DOI: 10.15252/embj.2022112858] [Citation(s) in RCA: 8] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2022] [Revised: 03/23/2023] [Accepted: 03/29/2023] [Indexed: 05/05/2023] Open
Abstract
The obligate anaerobic, enteric pathogen Clostridioides difficile persists in the intestinal tract by forming antibiotic-resistant endospores that contribute to relapsing and recurrent infections. Despite the importance of sporulation for C. difficile pathogenesis, environmental cues and molecular mechanisms that regulate sporulation initiation remain ill-defined. Here, by using RIL-seq to globally capture the Hfq-dependent RNA-RNA interactome, we discovered a network of small RNAs that bind to mRNAs encoding sporulation-related genes. We show that two of these small RNAs, SpoX and SpoY, regulate translation of the master regulator of sporulation, Spo0A, in an opposing manner, which ultimately leads to altered sporulation rates. Infection of antibiotic-treated mice with SpoX and SpoY deletion mutants revealed a global effect on gut colonization and intestinal sporulation. Our work uncovers an elaborate RNA-RNA interactome controlling the physiology and virulence of C. difficile and identifies a complex post-transcriptional layer in the regulation of spore formation in this important human pathogen.
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Affiliation(s)
- Manuela Fuchs
- Helmholtz Centre for Infection Research (HZI), Helmholtz Institute for RNA-based Infection Research (HIRI), Würzburg, Germany
- Faculty of Medicine, Institute for Molecular Infection Biology (IMIB), Julius-Maximilians-University of Würzburg (JMU), Würzburg, Germany
| | - Vanessa Lamm-Schmidt
- Helmholtz Centre for Infection Research (HZI), Helmholtz Institute for RNA-based Infection Research (HIRI), Würzburg, Germany
- Faculty of Medicine, Institute for Molecular Infection Biology (IMIB), Julius-Maximilians-University of Würzburg (JMU), Würzburg, Germany
| | - Tina Lenče
- Faculty of Medicine, Institute for Molecular Infection Biology (IMIB), Julius-Maximilians-University of Würzburg (JMU), Würzburg, Germany
| | - Johannes Sulzer
- Faculty of Medicine, Institute for Molecular Infection Biology (IMIB), Julius-Maximilians-University of Würzburg (JMU), Würzburg, Germany
| | - Arne Bublitz
- Helmholtz Centre for Infection Research (HZI), Braunschweig, Germany
| | - Janet Wackenreuter
- Helmholtz Centre for Infection Research (HZI), Helmholtz Institute for RNA-based Infection Research (HIRI), Würzburg, Germany
| | - Milan Gerovac
- Faculty of Medicine, Institute for Molecular Infection Biology (IMIB), Julius-Maximilians-University of Würzburg (JMU), Würzburg, Germany
| | - Till Strowig
- Helmholtz Centre for Infection Research (HZI), Braunschweig, Germany
- German Center for Infection Research (DZIF), Hannover-Braunschweig, Germany
| | - Franziska Faber
- Helmholtz Centre for Infection Research (HZI), Helmholtz Institute for RNA-based Infection Research (HIRI), Würzburg, Germany
- Faculty of Medicine, Institute for Molecular Infection Biology (IMIB), Julius-Maximilians-University of Würzburg (JMU), Würzburg, Germany
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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 PMCID: PMC11209739 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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15
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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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16
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Romero-Rodríguez A, Ruiz-Villafán B, Martínez-de la Peña CF, Sánchez S. Targeting the Impossible: A Review of New Strategies against Endospores. Antibiotics (Basel) 2023; 12:antibiotics12020248. [PMID: 36830159 PMCID: PMC9951900 DOI: 10.3390/antibiotics12020248] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2022] [Revised: 01/13/2023] [Accepted: 01/20/2023] [Indexed: 01/27/2023] Open
Abstract
Endospore-forming bacteria are ubiquitous, and their endospores can be present in food, in domestic animals, and on contaminated surfaces. Many spore-forming bacteria have been used in biotechnological applications, while others are human pathogens responsible for a wide range of critical clinical infections. Due to their resistant properties, it is challenging to eliminate spores and avoid the reactivation of latent spores that may lead to active infections. Furthermore, endospores play an essential role in the survival, transmission, and pathogenesis of some harmful strains that put human and animal health at risk. Thus, different methods have been applied for their eradication. Nevertheless, natural products are still a significant source for discovering and developing new antibiotics. Moreover, targeting the spore for clinical pathogens such as Clostridioides difficile is essential to disease prevention and therapeutics. These strategies could directly aim at the structural components of the spore or their germination process. This work summarizes the current advances in upcoming strategies and the development of natural products against endospores. This review also intends to highlight future perspectives in research and applications.
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Affiliation(s)
- Alba Romero-Rodríguez
- Departamento de Biología Molecular y Biotecnología, Instituto de Investigaciones Biomédicas, Universidad Nacional Autónoma de México, Ciudad de México 04510, Mexico
- Correspondence:
| | - Beatriz Ruiz-Villafán
- Departamento de Biología Molecular y Biotecnología, Instituto de Investigaciones Biomédicas, Universidad Nacional Autónoma de México, Ciudad de México 04510, Mexico
| | - Claudia Fabiola Martínez-de la Peña
- Centro de Investigaciones en Ciencias Microbiológicas, Instituto de Ciencias, Benemérita Universidad Autónoma de Puebla, Puebla 72592, Mexico
| | - Sergio Sánchez
- Departamento de Biología Molecular y Biotecnología, Instituto de Investigaciones Biomédicas, Universidad Nacional Autónoma de México, Ciudad de México 04510, Mexico
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17
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Nale JY, Thanki AM, Rashid SJ, Shan J, Vinner GK, Dowah ASA, Cheng JKJ, Sicheritz-Pontén T, Clokie MRJ. Diversity, Dynamics and Therapeutic Application of Clostridioides difficile Bacteriophages. Viruses 2022; 14:v14122772. [PMID: 36560776 PMCID: PMC9784644 DOI: 10.3390/v14122772] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2022] [Revised: 12/08/2022] [Accepted: 12/08/2022] [Indexed: 12/15/2022] Open
Abstract
Clostridioides difficile causes antibiotic-induced diarrhoea and pseudomembranous colitis in humans and animals. Current conventional treatment relies solely on antibiotics, but C. difficile infection (CDI) cases remain persistently high with concomitant increased recurrence often due to the emergence of antibiotic-resistant strains. Antibiotics used in treatment also induce gut microbial imbalance; therefore, novel therapeutics with improved target specificity are being investigated. Bacteriophages (phages) kill bacteria with precision, hence are alternative therapeutics for the targeted eradication of the pathogen. Here, we review current progress in C. difficile phage research. We discuss tested strategies of isolating C. difficile phages directly, and via enrichment methods from various sample types and through antibiotic induction to mediate prophage release. We also summarise phenotypic phage data that reveal their morphological, genetic diversity, and various ways they impact their host physiology and pathogenicity during infection and lysogeny. Furthermore, we describe the therapeutic development of phages through efficacy testing in different in vitro, ex vivo and in vivo infection models. We also discuss genetic modification of phages to prevent horizontal gene transfer and improve lysis efficacy and formulation to enhance stability and delivery of the phages. The goal of this review is to provide a more in-depth understanding of C. difficile phages and theoretical and practical knowledge on pre-clinical, therapeutic evaluation of the safety and effectiveness of phage therapy for CDI.
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Affiliation(s)
- Janet Y. Nale
- Centre for Epidemiology and Planetary Health, Department of Veterinary and Animal Science, Scotland’s Rural College, Inverness IV2 5NA, UK
- Department of Genetics and Genome Biology, University of Leicester, Leicester LE1 7RH, UK
| | - Anisha M. Thanki
- Department of Genetics and Genome Biology, University of Leicester, Leicester LE1 7RH, UK
| | - Srwa J. Rashid
- Department of Genetics and Genome Biology, University of Leicester, Leicester LE1 7RH, UK
| | - Jinyu Shan
- Department of Genetics and Genome Biology, University of Leicester, Leicester LE1 7RH, UK
| | - Gurinder K. Vinner
- Department of Genetics and Genome Biology, University of Leicester, Leicester LE1 7RH, UK
| | - Ahmed S. A. Dowah
- Department of Genetics and Genome Biology, University of Leicester, Leicester LE1 7RH, UK
- School of Pharmacy, University of Lincoln, Lincoln LN6 7TS, UK
| | | | - Thomas Sicheritz-Pontén
- Center for Evolutionary Hologenomics, The Globe Institute, University of Copenhagen, 1353 Copenhagen, Denmark
- Centre of Excellence for Omics-Driven Computational Biodiscovery, AIMST University, Bedong 08100, Kedah, Malaysia
| | - Martha R. J. Clokie
- Department of Genetics and Genome Biology, University of Leicester, Leicester LE1 7RH, UK
- Correspondence:
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18
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Response Regulator CD1688 Is a Negative Modulator of Sporulation in Clostridioides difficile. J Bacteriol 2022; 204:e0013022. [PMID: 35852332 PMCID: PMC9380558 DOI: 10.1128/jb.00130-22] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Two-component signal transduction systems (TCSs), consisting of a sensor histidine kinase (HK) and a response regulator (RR), sense environmental stimuli and then modulate cellular responses, typically through changes in gene expression. Our previous work identified the DNA binding motif of CD1586, an RR implicated in Clostridioides difficile strain R20291 sporulation. To determine the role of this RR in the sporulation pathway in C. difficile, we generated a deletion strain of cd1688 in the historical 630 strain, the homolog of cd1586. The C. difficile Δcd1688 strain exhibited a hypersporulation phenotype, suggesting that CD1688 negatively regulates sporulation. Complementation of the C. difficile Δcd1688 strain restored sporulation. In contrast, a nonphosphorylatable copy of cd1688 did not restore sporulation to wild-type (WT) levels, indicating that CD1688 must be phosphorylated to properly modulate sporulation. Expression of the master regulator spo0A, the sporulation-specific sigma factors sigF, sigE, sigG, and sigK, and a signaling protein encoded by spoIIR was increased in the C. difficile Δcd1688 strain compared to WT. In line with the increased spoIIR expression, we detected an increase in mature SigE at an earlier time point, which arises from SpoIIR-mediated processing of pro-SigE. Taken together, our data suggest that CD1688 is a novel negative modulator of sporulation in C. difficile and contributes to mediating progression through the spore developmental pathway. These results add to our growing understanding of the complex regulatory events involved in C. difficile sporulation, insight that could be exploited for novel therapeutic development. IMPORTANCEClostridioides difficile causes severe gastrointestinal illness and is a leading cause of nosocomial infections in the United States. This pathogen produces metabolically dormant spores that are the major vehicle of transmission between hosts. The sporulation pathway involves an intricate regulatory network that controls a succession of morphological changes necessary to produce spores. The environmental signals inducing the sporulation pathway are not well understood in C. difficile. This work identified a response regulator, CD1688, that, when deleted, led to a hypersporulation phenotype, indicating that it typically acts to repress sporulation. Improving our understanding of the regulatory mechanisms modulating sporulation in C. difficile could provide novel strategies to eliminate or reduce spore production, thus decreasing transmission and disease relapse.
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19
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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: 7] [Impact Index Per Article: 3.5] [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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20
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DiCandia MA, Edwards AN, Jones JB, Swaim GL, Mills BD, McBride SM. Identification of functional Spo0A residues critical for sporulation in Clostridioides difficile. J Mol Biol 2022; 434:167641. [PMID: 35597553 DOI: 10.1016/j.jmb.2022.167641] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2022] [Revised: 04/26/2022] [Accepted: 05/15/2022] [Indexed: 10/18/2022]
Abstract
Clostridioides difficile is an anaerobic, Gram-positive pathogen that is responsible for C. difficile infection (CDI). To survive in the environment and spread to new hosts, C. difficile must form metabolically dormant spores. The formation of spores requires activation of the transcription factor Spo0A, which is the master regulator of sporulation in all endospore-forming bacteria. Though the sporulation initiation pathway has been delineated in the Bacilli, including the model spore-former Bacillus subtilis, the direct regulators of Spo0A in C. difficile remain undefined. C. difficile Spo0A shares highly conserved protein interaction regions with the B. subtilis sporulation proteins Spo0F and Spo0A, although many of the interacting factors present in B. subtilis are not encoded in C. difficile. To determine if comparable Spo0A residues are important for C. difficile sporulation initiation, site-directed mutagenesis was performed at conserved receiver domain residues and the effects on sporulation were examined. Mutation of residues important for homodimerization and interaction with positive and negative regulators of B. subtilis Spo0A and Spo0F impacted C. difficile Spo0A function. The data also demonstrated that mutation of many additional conserved residues altered C. difficile Spo0A activity, even when the corresponding Bacillus interacting proteins are not apparent in the C. difficile genome. Finally, the conserved aspartate residue at position 56 of C. difficile Spo0A was determined to be the phosphorylation site that is necessary for Spo0A activation. The finding that Spo0A interacting motifs maintain functionality suggests that C. difficile Spo0A interacts with yet unidentified proteins that regulate its activity and control spore formation.
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Affiliation(s)
- Michael A DiCandia
- Department of Microbiology and Immunology, Emory University School of Medicine, Emory Antibiotic Resistance Center, Atlanta, GA, USA
| | - Adrianne N Edwards
- Department of Microbiology and Immunology, Emory University School of Medicine, Emory Antibiotic Resistance Center, Atlanta, GA, USA
| | - Joshua B Jones
- Department of Microbiology and Immunology, Emory University School of Medicine, Emory Antibiotic Resistance Center, Atlanta, GA, USA
| | - Grace L Swaim
- Department of Neuroscience and Cell Biology, Yale University Graduate School of Arts and Sciences, New Haven, CT, USA
| | - Brooke D Mills
- Department of Microbiology and Immunology, Emory University School of Medicine, Emory Antibiotic Resistance Center, Atlanta, GA, USA
| | - Shonna M McBride
- Department of Microbiology and Immunology, Emory University School of Medicine, Emory Antibiotic Resistance Center, Atlanta, GA, USA.
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21
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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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22
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Naskulwar K, Peña-Castillo L. sRNARFTarget: a fast machine-learning-based approach for transcriptome-wide sRNA target prediction. RNA Biol 2021; 19:44-54. [PMID: 34965197 PMCID: PMC8794260 DOI: 10.1080/15476286.2021.2012058] [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] [Indexed: 12/02/2022] Open
Abstract
Bacterial small regulatory RNAs (sRNAs) are key regulators of gene expression in many processes related to adaptive responses. A multitude of sRNAs have been identified in many bacterial species; however, their function has yet to be elucidated. A key step to understand sRNAs function is to identify the mRNAs these sRNAs bind to. There are several computational methods for sRNA target prediction, and the most accurate one is CopraRNA which is based on comparative-genomics. However, species-specific sRNAs are quite common and CopraRNA cannot be used for these sRNAs. The most commonly used transcriptome-wide sRNA target prediction method and second-most-accurate method is IntaRNA. However, IntaRNA can take hours to run on a bacterial transcriptome. Here we present sRNARFTarget, a machine-learning-based method for transcriptome-wide sRNA target prediction applicable to any sRNA. We comparatively assessed the performance of sRNARFTarget, CopraRNA and IntaRNA in three bacterial species. Our results show that sRNARFTarget outperforms IntaRNA in terms of accuracy, ranking of true interacting pairs, and running time. However, CopraRNA substantially outperforms the other two programsin terms of accuracy. Thus, we suggest using CopraRNA when homolog sequences of the sRNA are available, and sRNARFTarget for transcriptome-wide prediction or for species-specific sRNAs. sRNARFTarget is available at https://github.com/BioinformaticsLabAtMUN/sRNARFTarget.
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Affiliation(s)
- Kratika Naskulwar
- Department of Computer Science, Memorial University of Newfoundland, St. John's, Canada
| | - Lourdes Peña-Castillo
- Department of Computer Science, Memorial University of Newfoundland, St. John's, Canada.,Department of Biology, Memorial University of Newfoundland, St. John's, Canada
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23
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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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Monaghan TI, Baker JA, Krabben P, Davies ET, Jenkinson ER, Goodhead IB, Robinson GK, Shepherd M. Deletion of glyceraldehyde-3-phosphate dehydrogenase (gapN) in Clostridium saccharoperbutylacetonicum N1-4(HMT) using CLEAVE™ increases the ATP pool and accelerates solvent production. Microb Biotechnol 2021; 15:1574-1585. [PMID: 34927803 PMCID: PMC9049615 DOI: 10.1111/1751-7915.13990] [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: 06/04/2021] [Accepted: 11/27/2021] [Indexed: 11/28/2022] Open
Abstract
The development and advent of mutagenesis tools for solventogenic clostridial species in recent years has allowed for the increased refinement of industrially relevant strains. In this study we have utilised CLEAVE™, a CRISPR/Cas genome editing system developed by Green Biologics Ltd., to engineer a strain of Clostridium saccharoperbutylacetonicum N1-4(HMT) with potentially useful solvents titres and energy metabolism. As one of two enzymes responsible for the conversion of glyceraldehyde-3-phosphate (GAP) to 3-phosphoglyceric acid in glycolysis, it was hypothesised that deletion of gapN would increase ATP and NADH production that could in turn improve solvent production. Herein, whole genome sequencing has been used to evaluate CLEAVE™ and the successful knockout of gapN, demonstrating a clean knockout with no other detectable variations from the wild type sequence. Elevated solvent levels were detected during the first 24 h of batch fermentation, indicating an earlier shift to solventogenesis. A 2.4-fold increase in ATP concentration was observed, and quantitation of NAD(P)H derivatives revealed a more reducing cytoplasm for the gapN strain. These findings expand our understanding of clostridium carbon metabolism and report a new approach to optimising biofuel production.
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Affiliation(s)
- Taylor I Monaghan
- School of Biosciences, RAPID Group, University of Kent, Canterbury, CT2 7NJ, UK
| | - Joseph A Baker
- School of Biosciences, RAPID Group, University of Kent, Canterbury, CT2 7NJ, UK
| | - Preben Krabben
- Green Biologics Ltd, R&D Labs, 154AH Brook Drive, Milton Park, Abingdon, OX14 4SD, UK
| | - E Timothy Davies
- Green Biologics Ltd, R&D Labs, 154AH Brook Drive, Milton Park, Abingdon, OX14 4SD, UK
| | - Elizabeth R Jenkinson
- Green Biologics Ltd, R&D Labs, 154AH Brook Drive, Milton Park, Abingdon, OX14 4SD, UK
| | - Ian B Goodhead
- School of Science, Engineering & Environment, University of Salford, Lancashire, M5 4WT, UK
| | - Gary K Robinson
- School of Biosciences, RAPID Group, University of Kent, Canterbury, CT2 7NJ, UK
| | - Mark Shepherd
- School of Biosciences, RAPID Group, University of Kent, Canterbury, CT2 7NJ, UK
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25
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Lee CD, Rizvi A, Edwards AN, DiCandia MA, Vargas Cuebas GG, Monteiro MP, McBride SM. Genetic mechanisms governing sporulation initiation in Clostridioides difficile. Curr Opin Microbiol 2021; 66:32-38. [PMID: 34933206 DOI: 10.1016/j.mib.2021.12.001] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2021] [Revised: 12/03/2021] [Accepted: 12/05/2021] [Indexed: 12/15/2022]
Abstract
As an anaerobe, Clostridioides difficile relies on the formation of a dormant spore for survival outside of the mammalian host's gastrointestinal tract. The spore is recalcitrant to desiccation, numerous disinfectants, UV light, and antibiotics, permitting long-term survival against environmental insults and efficient transmission from host to host. Although the morphological stages of spore formation are similar between C. difficile and other well-studied endospore-forming bacteria, the C. difficile genome does not appear to encode many of the known, conserved regulatory factors that are necessary to initiate sporulation in other spore-forming bacteria. The absence of early sporulation-specific orthologs suggests that C. difficile has evolved to control sporulation initiation in response to its unique and specific ecological niche and environmental cues within the host. Here, we review our current understanding and highlight the recent discoveries that have begun to unravel the regulatory pathways and molecular mechanisms by which C. difficile induces spore formation.
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Affiliation(s)
- Cheyenne D Lee
- Department of Microbiology and Immunology, Emory University School of Medicine, Emory Antibiotic Resistance Center, Atlanta, GA, USA
| | - Arshad Rizvi
- Department of Microbiology and Immunology, Emory University School of Medicine, Emory Antibiotic Resistance Center, Atlanta, GA, USA
| | - Adrianne N Edwards
- Department of Microbiology and Immunology, Emory University School of Medicine, Emory Antibiotic Resistance Center, Atlanta, GA, USA
| | - Michael A DiCandia
- Department of Microbiology and Immunology, Emory University School of Medicine, Emory Antibiotic Resistance Center, Atlanta, GA, USA
| | - Germán G Vargas Cuebas
- Department of Microbiology and Immunology, Emory University School of Medicine, Emory Antibiotic Resistance Center, Atlanta, GA, USA
| | - Marcos P Monteiro
- Department of Microbiology and Immunology, Emory University School of Medicine, Emory Antibiotic Resistance Center, Atlanta, GA, USA
| | - Shonna M McBride
- Department of Microbiology and Immunology, Emory University School of Medicine, Emory Antibiotic Resistance Center, Atlanta, GA, USA.
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Arrieta-Ortiz ML, Immanuel SRC, Turkarslan S, Wu WJ, Girinathan BP, Worley JN, DiBenedetto N, Soutourina O, Peltier J, Dupuy B, Bry L, Baliga NS. Predictive regulatory and metabolic network models for systems analysis of Clostridioides difficile. Cell Host Microbe 2021; 29:1709-1723.e5. [PMID: 34637780 PMCID: PMC8595754 DOI: 10.1016/j.chom.2021.09.008] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2021] [Revised: 07/29/2021] [Accepted: 09/16/2021] [Indexed: 12/15/2022]
Abstract
We present predictive models for comprehensive systems analysis of Clostridioides difficile, the etiology of pseudomembranous colitis. By leveraging 151 published transcriptomes, we generated an EGRIN model that organizes 90% of C. difficile genes into a transcriptional regulatory network of 297 co-regulated modules, implicating genes in sporulation, carbohydrate transport, and metabolism. By advancing a metabolic model through addition and curation of metabolic reactions including nutrient uptake, we discovered 14 amino acids, diverse carbohydrates, and 10 metabolic genes as essential for C. difficile growth in the intestinal environment. Finally, we developed a PRIME model to uncover how EGRIN-inferred combinatorial gene regulation by transcription factors, such as CcpA and CodY, modulates essential metabolic processes to enable C. difficile growth relative to commensal colonization. The C. difficile interactive web portal provides access to these model resources to support collaborative systems-level studies of context-specific virulence mechanisms in C. difficile.
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Affiliation(s)
| | | | | | - Wei-Ju Wu
- Institute for Systems Biology, Seattle, WA 98109, USA
| | - Brintha P Girinathan
- Massachusetts Host-Microbiome Center, Brigham & Women's Hospital, Harvard Medical School, Boston, MA 02115, USA
| | - Jay N Worley
- Massachusetts Host-Microbiome Center, Brigham & Women's Hospital, Harvard Medical School, Boston, MA 02115, USA
| | - Nicholas DiBenedetto
- Massachusetts Host-Microbiome Center, Brigham & Women's Hospital, Harvard Medical School, Boston, MA 02115, USA
| | - Olga Soutourina
- Université Paris-Saclay, CEA, CNRS, Institute for Integrative Biology of the Cell (I2BC), Gif-sur-yvette 91198, France
| | - Johann Peltier
- Université Paris-Saclay, CEA, CNRS, Institute for Integrative Biology of the Cell (I2BC), Gif-sur-yvette 91198, France
| | - Bruno Dupuy
- Laboratoire Pathogenèse des Bactéries anaérobies, Institut Pasteur, Université de Paris, UMR CNRS 2001, Paris 75015, France
| | - Lynn Bry
- Massachusetts Host-Microbiome Center, Brigham & Women's Hospital, Harvard Medical School, Boston, MA 02115, USA
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Shen A. Clostridioides difficile Spore Formation and Germination: New Insights and Opportunities for Intervention. Annu Rev Microbiol 2021; 74:545-566. [PMID: 32905755 DOI: 10.1146/annurev-micro-011320-011321] [Citation(s) in RCA: 21] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Spore formation and germination are essential for the bacterial pathogen Clostridioides difficile to transmit infection. Despite the importance of these developmental processes to the infection cycle of C. difficile, the molecular mechanisms underlying how this obligate anaerobe forms infectious spores and how these spores germinate to initiate infection were largely unknown until recently. Work in the last decade has revealed that C. difficile uses a distinct mechanism for sensing and transducing germinant signals relative to previously characterized spore formers. The C. difficile spore assembly pathway also exhibits notable differences relative to Bacillus spp., where spore formation has been more extensively studied. For both these processes, factors that are conserved only in C. difficile or the related Peptostreptococcaceae family are employed, and even highly conserved spore proteins can have differential functions or requirements in C. difficile compared to other spore formers. This review summarizes our current understanding of the mechanisms controlling C. difficile spore formation and germination and describes strategies for inhibiting these processes to prevent C. difficile infection and disease recurrence.
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Affiliation(s)
- Aimee Shen
- Department of Molecular Biology and Microbiology, Tufts University School of Medicine, Boston, Massachusetts 02111, USA;
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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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29
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A cortex-specific penicillin-binding protein contributes to heat resistance in Clostridioides difficile spores. Anaerobe 2021; 70:102379. [PMID: 33940167 PMCID: PMC8417463 DOI: 10.1016/j.anaerobe.2021.102379] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2021] [Revised: 04/12/2021] [Accepted: 04/23/2021] [Indexed: 12/15/2022]
Abstract
Background Sporulation is a complex cell differentiation programme shared by many members of the Firmicutes, the end result of which is a highly resistant, metabolically inert spore that can survive harsh environmental insults. Clostridioides difficile spores are essential for transmission of disease and are also required for recurrent infection. However, the molecular basis of sporulation is poorly understood, despite parallels with the well-studied Bacillus subtilis system. The spore envelope consists of multiple protective layers, one of which is a specialised layer of peptidoglycan, called the cortex, that is essential for the resistant properties of the spore. We set out to identify the enzymes required for synthesis of cortex peptidoglycan in C. difficile. Methods Bioinformatic analysis of the C. difficile genome to identify putative homologues of Bacillus subtilis spoVD was combined with directed mutagenesis and microscopy to identify and characterise cortex-specific PBP activity. Results Deletion of CDR20291_2544 (SpoVDCd) abrogated spore formation and this phenotype was completely restored by complementation in cis. Analysis of SpoVDCd revealed a three domain structure, consisting of dimerization, transpeptidase and PASTA domains, very similar to B. subtilis SpoVD. Complementation with SpoVDCd domain mutants demonstrated that the PASTA domain was dispensable for formation of morphologically normal spores. SpoVDCd was also seen to localise to the developing spore by super-resolution confocal microscopy. Conclusions We have identified and characterised a cortex specific PBP in C. difficile. This is the first characterisation of a cortex-specific PBP in C. difficile and begins the process of unravelling cortex biogenesis in this important pathogen. CDR20291_2544 encodes a C. difficile homologue of the B subtilis SpoVD. Mutation of spoVDCd completely prevents the formation of heat-resistant spores. The SpoVDCd PASTA domain was dispensable for its function. SpoVDCd localises to the developing spore.
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30
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Martins D, DiCandia MA, Mendes AL, Wetzel D, McBride SM, Henriques AO, Serrano M. CD25890, a conserved protein that modulates sporulation initiation in Clostridioides difficile. Sci Rep 2021; 11:7887. [PMID: 33846410 PMCID: PMC8041843 DOI: 10.1038/s41598-021-86878-9] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2020] [Accepted: 03/17/2021] [Indexed: 12/16/2022] Open
Abstract
Bacteria that reside in the gastrointestinal tract of healthy humans are essential for our health, sustenance and well-being. About 50-60% of those bacteria have the ability to produce resilient spores that are important for the life cycle in the gut and for host-to-host transmission. A genomic signature for sporulation in the human intestine was recently described, which spans both commensals and pathogens such as Clostridioides difficile and contains several genes of unknown function. We report on the characterization of a signature gene, CD25890, which, as we show is involved in the control of sporulation initiation in C. difficile under certain nutritional conditions. Spo0A is the main regulatory protein controlling entry into sporulation and we show that an in-frame deletion of CD25890 results in increased expression of spo0A per cell and increased sporulation. The effect of CD25890 on spo0A is likely indirect and mediated through repression of the sinRR´ operon. Deletion of the CD25890 gene, however, does not alter the expression of the genes coding for the cytotoxins or the genes involved in biofilm formation. Our results suggest that CD25890 acts to modulate sporulation in response to the nutrients present in the environment.
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Affiliation(s)
- Diogo Martins
- Instituto de Tecnologia Química E Biológica António Xavier, Avenida da República, 2780-157, Oeiras, Portugal
| | - Michael A DiCandia
- Department of Microbiology and Immunology, Emory University School of Medicine, Atlanta, GA, USA
| | - Aristides L Mendes
- Instituto de Tecnologia Química E Biológica António Xavier, Avenida da República, 2780-157, Oeiras, Portugal
| | - Daniela Wetzel
- Department of Microbiology and Immunology, Emory University School of Medicine, Atlanta, GA, USA
| | - Shonna M McBride
- Department of Microbiology and Immunology, Emory University School of Medicine, Atlanta, GA, USA
| | - Adriano O Henriques
- Instituto de Tecnologia Química E Biológica António Xavier, Avenida da República, 2780-157, Oeiras, Portugal
| | - Mónica Serrano
- Instituto de Tecnologia Química E Biológica António Xavier, Avenida da República, 2780-157, Oeiras, Portugal.
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31
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Beskrovnaya P, Sexton DL, Golmohammadzadeh M, Hashimi A, Tocheva EI. Structural, Metabolic and Evolutionary Comparison of Bacterial Endospore and Exospore Formation. Front Microbiol 2021; 12:630573. [PMID: 33767680 PMCID: PMC7985256 DOI: 10.3389/fmicb.2021.630573] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2020] [Accepted: 02/15/2021] [Indexed: 12/20/2022] Open
Abstract
Sporulation is a specialized developmental program employed by a diverse set of bacteria which culminates in the formation of dormant cells displaying increased resilience to stressors. This represents a major survival strategy for bacteria facing harsh environmental conditions, including nutrient limitation, heat, desiccation, and exposure to antimicrobial compounds. Through dispersal to new environments via biotic or abiotic factors, sporulation provides a means for disseminating genetic material and promotes encounters with preferable environments thus promoting environmental selection. Several types of bacterial sporulation have been characterized, each involving numerous morphological changes regulated and performed by non-homologous pathways. Despite their likely independent evolutionary origins, all known modes of sporulation are typically triggered by limited nutrients and require extensive membrane and peptidoglycan remodeling. While distinct modes of sporulation have been observed in diverse species, two major types are at the forefront of understanding the role of sporulation in human health, and microbial population dynamics and survival. Here, we outline endospore and exospore formation by members of the phyla Firmicutes and Actinobacteria, respectively. Using recent advances in molecular and structural biology, we point to the regulatory, genetic, and morphological differences unique to endo- and exospore formation, discuss shared characteristics that contribute to the enhanced environmental survival of spores and, finally, cover the evolutionary aspects of sporulation that contribute to bacterial species diversification.
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Affiliation(s)
| | | | | | | | - Elitza I. Tocheva
- Department of Microbiology and Immunology, Life Sciences Institute, Health Sciences Mall, The University of British Columbia, Vancouver, BC, Canada
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32
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Combined and Distinct Roles of Agr Proteins in Clostridioides difficile 630 Sporulation, Motility, and Toxin Production. mBio 2020; 11:mBio.03190-20. [PMID: 33443122 PMCID: PMC8534292 DOI: 10.1128/mbio.03190-20] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The Clostridioides difficile accessory gene regulator 1 (agr1) locus consists of two genes, agrB1 and agrD1, that presumably constitute an autoinducing peptide (AIP) system. Typically, AIP systems function through the AgrB-mediated processing of AgrD to generate a processed form of the AIP that provides a concentration-dependent extracellular signal. Here, we show that the C. difficile 630 Agr1 system has multiple functions, not all of which depend on AgrB1. CRISPR-Cas9n deletion of agrB1, agrD1, or the entire locus resulted in changes in transcription of sporulation-related factors and an overall loss in spore formation. Sporulation was recovered in the mutants by providing supernatant from stationary-phase cultures of the parental strain. In contrast, C. difficile motility was reduced only when both AgrB1 and AgrD1 were disrupted. Finally, in the absence of AgrB1, the AgrD1 peptide accumulated within the cytoplasm and this correlated with increased expression of tcdR (15-fold), as well as tcdA (20-fold) and tcdB (5-fold), which encode the two major C. difficile toxins. The combined deletion of agrB1/agrD1 or deletion of only agrD1 did not significantly alter expression of tcdR or tcdB but did show a minor effect on tcdA expression. Overall, these data indicate that the Agr1-based system in C. difficile 630 carries out multiple functions, some of which are associated with prototypical AIP signaling and others of which involve previously undescribed mechanisms of action.IMPORTANCE C. difficile is a spore-forming, toxigenic, anaerobic bacterium that causes severe gastrointestinal illness. Understanding the ways in which C. difficile senses growth conditions to regulate toxin expression and sporulation is essential to advancing our understanding of this pathogen. The Agr1 system in C. difficile has been thought to function by generating an extracellular autoinducing peptide that accumulates and exogenously activates two-component signaling. The absence of the peptide or protease should, in theory, result in similar phenotypes. However, in contrast to longstanding assumptions about Agr, we found that mutants of individual agr1 genes exhibit distinct phenotypes in C. difficile These findings suggest that the Agr1 system may have other regulatory mechanisms independent of the typical Agr quorum sensing system. These data not only challenge models for Agr's mechanism of action in C. difficile but also may expand our conceptions of how this system works in other Gram-positive pathogens.
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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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Romo JA, Markey L, Kumamoto CA. Lipid Species in the GI Tract are Increased by the Commensal Fungus Candida albicans and Decrease the Virulence of Clostridioides difficile. J Fungi (Basel) 2020; 6:E100. [PMID: 32635220 PMCID: PMC7557729 DOI: 10.3390/jof6030100] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2020] [Revised: 06/18/2020] [Accepted: 06/30/2020] [Indexed: 12/12/2022] Open
Abstract
Prior antibiotic treatment is a risk factor for Clostridioides difficile infection (CDI); the commensal gut microbiota plays a key role in determining host susceptibility to the disease. Previous studies demonstrate that the pre-colonization of mice with a commensal fungus, Candida albicans, protects against a lethal challenge with C. difficile spores. The results reported here demonstrate that the cecum contents of antibiotic-treated mice with C. albicans colonization contained different levels of several lipid species, including non-esterified, unsaturated long-chain fatty acids compared to non-C. albicans-colonized mice. Mice fed olive oil for one week and challenged with C. difficile spores showed enhanced survival compared to PBS-fed mice. The amount of olive oil administered was not sufficient to cause weight gain or to result in significant changes to the bacterial microbiota, in contrast to the effects of a high-fat diet. Furthermore, the direct exposure of C. difficile bacteria in laboratory culture to the unsaturated fatty acid oleic acid, the major fatty acid found in olive oil, reduced the transcription of genes encoding the toxins and reduced the survival of bacteria in the post-exponential phase. Therefore, the effects of C. albicans on the metabolite milieu contributed to the attenuation of C. difficile virulence.
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Affiliation(s)
- Jesus A. Romo
- Department of Molecular Biology and Microbiology, Tufts University, Boston, MA 02111, USA
| | - Laura Markey
- Graduate Program in Molecular Microbiology, Graduate School of Biomedical Sciences and Department of Molecular Biology and Microbiology, Tufts University, Boston, MA 02111, USA;
| | - Carol A. Kumamoto
- Department of Molecular Biology and Microbiology, Tufts University, Boston, MA 02111, USA
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35
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Xin X, Cheng C, Du G, Chen L, Xue C. Metabolic Engineering of Histidine Kinases in Clostridium beijerinckii for Enhanced Butanol Production. Front Bioeng Biotechnol 2020; 8:214. [PMID: 32266241 PMCID: PMC7098912 DOI: 10.3389/fbioe.2020.00214] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2020] [Accepted: 03/03/2020] [Indexed: 12/31/2022] Open
Abstract
Clostridium beijerinckii, a promising industrial microorganism for butanol production, suffers from low butanol titer and lack of high-efficiency genetical engineering toolkit. A few histidine kinases (HKs) responsible for Spo0A phosphorylation have been demonstrated as functionally important components in regulating butanol biosynthesis in solventogenic clostridia such as C. acetobutylicum, but no study about HKs has been conducted in C. beijerinckii. In this study, six annotated but uncharacterized candidate HK genes sharing partial homologies (no less than 30%) with those in C. acetobutylicum were selected based on sequence alignment. The encoding region of these HK genes were deleted with CRISPR-Cas9n-based genome editing technology. The deletion of cbei2073 and cbei4484 resulted in significant change in butanol biosynthesis, with butanol production increased by 40.8 and 17.3% (13.8 g/L and 11.5 g/L vs. 9.8 g/L), respectively, compared to the wild-type. Faster butanol production rates were observed, with butanol productivity greatly increased by 40.0 and 20.0%, respectively, indicating these two HKs are important in regulating cellular metabolism in C. beijerinckii. In addition, the sporulation frequencies of two HKs inactivated strains decreased by 96.9 and 77.4%, respectively. The other four HK-deletion (including cbei2087, cbei2435, cbei4925, and cbei1553) mutant strains showed few phenotypic changes compared with the wild-type. This study demonstrated the role of HKs on sporulation and solventogenesis in C. beijerinckii, and provided a novel engineering strategy of HKs for improving metabolite production. The hyper-butanol-producing strains generated in this study have great potentials in industrial biobutanol production.
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Affiliation(s)
- Xin Xin
- School of Bioengineering, Dalian University of Technology, Dalian, China
| | - Chi Cheng
- School of Bioengineering, Dalian University of Technology, Dalian, China
| | - Guangqing Du
- School of Bioengineering, Dalian University of Technology, Dalian, China
| | - Lijie Chen
- School of Bioengineering, Dalian University of Technology, Dalian, China
| | - Chuang Xue
- School of Bioengineering, Dalian University of Technology, Dalian, China
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Chilton CH, Crowther GS, Miossec C, de Gunzburg J, Andremont A, Wilcox MH. Investigation of the effect of the adsorbent DAV131A on the propensity of moxifloxacin to induce simulated Clostridioides (Clostridium) difficile infection (CDI) in an in vitro human gut model. J Antimicrob Chemother 2020; 75:1458-1465. [DOI: 10.1093/jac/dkaa062] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2019] [Revised: 01/17/2020] [Accepted: 01/31/2020] [Indexed: 12/20/2022] Open
Abstract
Abstract
Background
Clostridioides difficile infection (CDI) remains a high burden worldwide. DAV131A, a novel adsorbent, reduces residual gut antimicrobial levels, reducing CDI risk in animal models.
Objectives
We used a validated human gut model to investigate the efficacy of DAV131A in preventing moxifloxacin-induced CDI.
Methods
C. difficile (CD) spores were inoculated into two models populated with pooled human faeces. Moxifloxacin was instilled (43 mg/L, once daily, 7 days) alongside DAV131A (5 g in 18 mL PBS, three times daily, 14 days, Model A), or PBS (18 mL, three times daily, 14 days, Model B). Selected gut microbiota populations, CD total counts, spore counts, cytotoxin titre and antimicrobial concentrations (HPLC) were monitored daily. We monitored for reduced susceptibility of CD to moxifloxacin. Growth of CD in faecal filtrate and medium in the presence/absence of DAV131A, or in medium pre-treated with DAV131A, was also investigated.
Results
DAV131A instillation reduced active moxifloxacin levels to below the limit of detection (50 ng/mL), and prevented microbiota disruption, excepting Bacteroides fragilis group populations, which declined by ∼3 log10 cfu/mL. DAV131A delayed onset of simulated CDI by ∼2 weeks, but did not prevent CD germination and toxin production. DAV131A prevented emergence of reduced susceptibility of CD to moxifloxacin. In batch culture, DAV131A had minor effects on CD vegetative growth, but significantly reduced toxin/spores (P < 0.005).
Conclusions
DAV131A reduced moxifloxacin-induced microbiota disruption and emergence of antibiotic-resistant CD. Delayed onset of CD germination and toxin production indicates further investigations are warranted to understand the clinical benefits of DAV131A in CDI prevention.
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Affiliation(s)
- C H Chilton
- Healthcare Associated Infections Research Group, Leeds Institute for Medical Research, University of Leeds, Old Medical School, Leeds General Infirmary, Leeds LS1 3EX, UK
| | - G S Crowther
- Division of Pharmacy and Optometry, University of Manchester, Manchester M13 9PT, UK
| | - C Miossec
- Da Volterra, Le Dorian (bât B1), 172 rue de Charonne, 75011 Paris, France
| | - J de Gunzburg
- Da Volterra, Le Dorian (bât B1), 172 rue de Charonne, 75011 Paris, France
| | - A Andremont
- IAME INSERM, UMR 1137, University of Paris, 75018 Paris, France
| | - M H Wilcox
- Healthcare Associated Infections Research Group, Leeds Institute for Medical Research, University of Leeds, Old Medical School, Leeds General Infirmary, Leeds LS1 3EX, UK
- Microbiology, Leeds Teaching Hospitals NHS Trust, Old Medical School, Leeds General Infirmary, Leeds LS1 3EX, UK
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Insights into the Role of Human Gut Microbiota in Clostridioides difficile Infection. Microorganisms 2020; 8:microorganisms8020200. [PMID: 32023967 PMCID: PMC7074861 DOI: 10.3390/microorganisms8020200] [Citation(s) in RCA: 36] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2020] [Revised: 01/29/2020] [Accepted: 01/31/2020] [Indexed: 12/18/2022] Open
Abstract
Clostridioides difficile infection (CDI) has emerged as a major health problem worldwide. A major risk factor for disease development is prior antibiotic use, which disrupts the normal gut microbiota by altering its composition and the gut’s metabolic functions, leading to the loss of colonization resistance and subsequent CDI. Data from human studies have shown that the presence of C. difficile, either as a colonizer or as a pathogen, is associated with a decreased level of gut microbiota diversity. The investigation of the gut’s microbial communities, in both healthy subjects and patients with CDI, elucidate the role of microbiota and improve the current biotherapeutics for patients with CDI. Fecal microbiota transplantation has a major role in managing CDI, aiming at re-establishing colonization resistance in the host gastrointestinal tract by replenishing the gut microbiota. New techniques, such as post-genomics, proteomics and metabolomics analyses, can possibly determine in the future the way in which C. difficile eradicates colonization resistance, paving the way for the development of new, more successful treatments and prevention. The aim of the present review is to present recent data concerning the human gut microbiota with a focus on its important role in health and disease.
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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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Connor MC, McGrath JW, McMullan G, Marks N, Guelbenzu M, Fairley DJ. Emergence of a non-sporulating secondary phenotype in Clostridium (Clostridioides) difficile ribotype 078 isolated from humans and animals. Sci Rep 2019; 9:13722. [PMID: 31548637 PMCID: PMC6757067 DOI: 10.1038/s41598-019-50285-y] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2019] [Accepted: 08/27/2019] [Indexed: 11/09/2022] Open
Abstract
Clostridium (Clostridioides) difficile is a Gram positive, spore forming anaerobic bacterium that is a leading cause of antibiotic associated diarrhoea in the developed world. C. difficile is a genetically diverse species that can be divided into 8 phylogenetically distinct clades with clade 5 found to be genetically distant from all others. Isolates with the PCR ribotype 078 belong to clade 5, and are often associated with C. difficile infection in both humans and animals. Colonisation of animals and humans by ribotype 078 raises questions about possible zoonotic transmission, and also the diversity of reservoirs for ribotype 078 strains within the environment. One of the key factors which enables C. difficile to be a successful, highly transmissible pathogen is its ability to produce oxygen resistant spores capable of surviving harsh conditions. Here we describe the existence of a non-sporulating variant of C. difficile ribotype 078 harbouring mutations leading to premature stop codons within the master regulator, Spo0A. As sporulation is imperative to the successful transmission of C. difficile this study was undertaken to investigate phenotypic characteristics of this asporogenous phenotype with regards to growth rate, antibiotic susceptibility, toxin production and biofilm formation.
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Affiliation(s)
- M C Connor
- School of Biological Sciences and the Institute for Global Food Security, Queen's University Belfast, Belfast, UK.
| | - J W McGrath
- School of Biological Sciences and the Institute for Global Food Security, Queen's University Belfast, Belfast, UK
| | - G McMullan
- School of Biological Sciences and the Institute for Global Food Security, Queen's University Belfast, Belfast, UK
| | - N Marks
- School of Biological Sciences and the Institute for Global Food Security, Queen's University Belfast, Belfast, UK
| | - M Guelbenzu
- Veterinary Science Division, Agri-Food Biosciences Institute, Belfast, UK.,Animal Health Ireland, Carrick on Shannon, Republic of Ireland
| | - D J Fairley
- Department of Microbiology, Belfast Health & Social Care Trust, Belfast, UK
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40
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Hughes A, Wilson S, Dodson EJ, Turkenburg JP, Wilkinson AJ. Crystal structure of the putative peptide-binding protein AppA from Clostridium difficile. Acta Crystallogr F Struct Biol Commun 2019; 75:246-253. [PMID: 30950825 PMCID: PMC6450515 DOI: 10.1107/s2053230x1900178x] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2018] [Accepted: 01/30/2019] [Indexed: 12/21/2022] Open
Abstract
Peptides play an important signalling role in Bacillus subtilis, where their uptake by one of two ABC-type oligopeptide transporters, Opp and App, is required for efficient sporulation. Homologues of these transporters in Clostridium difficile have been characterized, but their role, and hence that of peptides, in regulating sporulation in this organism is less clear. Here, the oligopeptide-binding receptor proteins for these transporters, CdAppA and CdOppA, have been purified and partially characterized, and the crystal structure of CdAppA has been determined in an open unliganded form. Peptide binding to either protein could not be observed in Thermofluor assays with a set of ten peptides of varying lengths and compositions. Re-examination of the protein sequences together with structure comparisons prompts the proposal that CdAppA is not a versatile peptide-binding protein but instead may bind a restricted set of peptides. Meanwhile, CdOppA is likely to be the receptor protein for a nickel-uptake system.
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Affiliation(s)
- Adam Hughes
- Structural Biology Laboratory, Department of Chemistry, University of York, York YO10 5DD, England
| | - Samuel Wilson
- Structural Biology Laboratory, Department of Chemistry, University of York, York YO10 5DD, England
| | - Eleanor J. Dodson
- Structural Biology Laboratory, Department of Chemistry, University of York, York YO10 5DD, England
| | - Johan P. Turkenburg
- Structural Biology Laboratory, Department of Chemistry, University of York, York YO10 5DD, England
| | - Anthony J. Wilkinson
- Structural Biology Laboratory, Department of Chemistry, University of York, York YO10 5DD, England
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41
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Camorlinga M, Sanchez-Rojas M, Torres J, Romo-Castillo M. Phenotypic Characterization of Non-toxigenic Clostridioides difficile Strains Isolated From Patients in Mexico. Front Microbiol 2019; 10:84. [PMID: 30774626 PMCID: PMC6367242 DOI: 10.3389/fmicb.2019.00084] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2018] [Accepted: 01/16/2019] [Indexed: 02/04/2023] Open
Abstract
Clostridioides difficile is a Gram positive, sporulated, rod-shape, anaerobic pathogen responsible for nosocomial diarrhea and colitis, mainly in antibiotic treated patients. C. difficile produce two toxins responsible for disease, toxin A (TcdA) and toxin B (TcdB), although not all strains produce them. Non-toxigenic C. difficile (NTCD) strains are able to colonize the intestinal mucosa and are often isolated from asymptomatic individuals. NTCD are poorly studied, their evolutionary history has not been elucidated, and their relationship with illness remains controversial. The aim of this work was to analyze the phenotype of NTCD strains isolated from clinical cases in hospitals of México, and whether NTCD strains present characteristics that differentiate them from the toxigenic strains. Seventy-four C. difficile strains isolated from patients were tested for cytotoxicity and 14 were identified as NTCD strains. We analyzed phenotypical characteristics that are important for the biology of C. difficile like colony morphology, antibiotic resistance, motility, sporulation, and adherence. Strains were also genotyped to determine the presence of genes coding for TcdA, TcdB and binary toxin and ribotyped for 027 type. When compared with toxigenic strains, NTCD strains presented an enlarged branched colony morphology, higher resistance to metronidazole, and increased sporulation efficiency. This phenotype has been reported associated with mutations that regulates phenotypic characteristics like swimming, sporulation or adhesion. Our results show that phenotype of NTCD strains is heterogeneous but still present characteristics that differentiate them from toxigenic strains.
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Affiliation(s)
- Margarita Camorlinga
- Unidad de Investigación Médica en Enfermedades Infecciosas y Parasitarias, Hospital de Pediatría, Centro Médico Nacional Siglo XXI, Instituto Mexicano del Seguro Social, Mexico City, Mexico
| | | | - Javier Torres
- Unidad de Investigación Médica en Enfermedades Infecciosas y Parasitarias, Hospital de Pediatría, Centro Médico Nacional Siglo XXI, Instituto Mexicano del Seguro Social, Mexico City, Mexico
| | - Mariana Romo-Castillo
- CONACYT-IMSS, Unidad de Investigación Médica en Enfermedades Infecciosas y Parasitarias, Hospital de Pediatría, Centro Médico Nacional Siglo XXI, IMSS, Mexico City, Mexico
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42
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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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Identification of an Important Orphan Histidine Kinase for the Initiation of Sporulation and Enterotoxin Production by Clostridium perfringens Type F Strain SM101. mBio 2019; 10:mBio.02674-18. [PMID: 30670619 PMCID: PMC6343041 DOI: 10.1128/mbio.02674-18] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Clostridium perfringens type F enteric diseases, which include a very common form of food poisoning and many cases of antibiotic-associated diarrhea, develop when type F strains sporulate and produce C. perfringens enterotoxin (CPE) in the intestines. Spores are also important for transmission of type F disease. Despite the importance of sporulation for type F disease and the evidence that C. perfringens sporulation begins with phosphorylation of the Spo0A transcriptional regulator, the kinase phosphorylating Spo0A to initiate sporulation and CPE production had not been ascertained. In response, the current report now provides identification of an orphan histidine kinase named CPR0195 that can directly phosphorylate Spo0A. Results using a CPR0195 null mutant indicate that this kinase is very important for initiating C. perfringens sporulation and CPE production. Therefore, the CPR0195 kinase represents a potential target to block type F disease by interfering with intestinal C. perfringens sporulation and CPE production. Clostridium perfringens type F strains cause a common human foodborne illness and many cases of nonfoodborne human gastrointestinal diseases. Sporulation plays two critical roles during type F enteric disease. First, it produces broadly resistant spores that facilitate type F strain survival in the food and nosocomial environments. Second, production of C. perfringens enterotoxin (CPE), the toxin responsible for causing the enteric symptoms of type F diseases, is restricted to cells in the process of sporulation. While later steps in the regulation of C. perfringens sporulation have been discerned, the process leading to phosphorylation of Spo0A, the master early regulator of sporulation and consequent CPE production, has remained unknown. Using an insertional mutagenesis approach, the current study identified the orphan histidine kinase CPR0195 as an important factor regulating C. perfringens sporulation and CPE production. Specifically, a CPR0195 null mutant of type F strain SM101 made 103-fold fewer spores than its wild-type parent and produced no detectable CPE. In contrast, a null mutant of another putative C. perfringens orphan histidine kinase (CPR1055) did not significantly affect sporulation or CPE production. Studies using a spoIIA operon promoter-driven reporter plasmid indicated that CPR0195 functions early during sporulation, i.e., prior to production of sporulation-associated sigma factors. Furthermore, in vitro studies showed that the CPR0195 kinase domain can autophosphorylate and phosphorylate Spo0A. These results support the idea of CPR0195 as an important kinase that initiates C. perfringens sporulation by directly phosphorylating Spo0A. This kinase could represent a novel therapeutic target to block C. perfringens sporulation and CPE production during type F disease.
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Evaluation of growth and sporulation of a non-toxigenic strain of Clostridioides difficile (Z31) and its shelf viability. Braz J Microbiol 2019; 50:263-269. [PMID: 30637658 DOI: 10.1007/s42770-018-0023-4] [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: 02/16/2018] [Accepted: 08/07/2018] [Indexed: 10/27/2022] Open
Abstract
The oral administration of non-toxigenic strains of Clostridioides difficile (NTCD) is currently showing promising results for the prevention of Clostridioides difficile infection (CDI) in humans and animals, and is being considered as a possible commercial product to be used in the near future. The aim of this work was to evaluate five culture media for the growth and sporulation of one NTCD (Z31) and evaluate the viability of a lyophilized spore solution of NTCD Z31 stored at 4 °C or at 25 °C for 2 years. Reinforced clostridial medium (RCM) and brain heart infusion broth (BHI) provided the highest production of NTCD Z31 spores. In the first 6 months of the storage of the lyophilized solution, a reduction in spore count of approximately 0.3 Log10 CFU/mL was observed; however, no further significant reduction in spore count was observed up to 24 months. No difference in spore concentration was found between the two storage temperatures from 6 to 24 months of storage. The present work showed BHI and RCM to be the best choices for the growth and sporulation of NTCD Z31 and suggested that the spores of NTCD Z31 are stable for up to 2 years under both temperature conditions.
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45
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Increased sporulation underpins adaptation of Clostridium difficile strain 630 to a biologically-relevant faecal environment, with implications for pathogenicity. Sci Rep 2018; 8:16691. [PMID: 30420658 PMCID: PMC6232153 DOI: 10.1038/s41598-018-35050-x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2018] [Accepted: 10/24/2018] [Indexed: 02/07/2023] Open
Abstract
Clostridium difficile virulence is driven primarily by the processes of toxinogenesis and sporulation, however many in vitro experimental systems for studying C. difficile physiology have arguably limited relevance to the human colonic environment. We therefore created a more physiologically–relevant model of the colonic milieu to study gut pathogen biology, incorporating human faecal water (FW) into growth media and assessing the physiological effects of this on C. difficile strain 630. We identified a novel set of C. difficile–derived metabolites in culture supernatants, including hexanoyl– and pentanoyl–amino acid derivatives by LC-MSn. Growth of C. difficile strain 630 in FW media resulted in increased cell length without altering growth rate and RNA sequencing identified 889 transcripts as differentially expressed (p < 0.001). Significantly, up to 300–fold increases in the expression of sporulation–associated genes were observed in FW media–grown cells, along with reductions in motility and toxin genes’ expression. Moreover, the expression of classical stress–response genes did not change, showing that C. difficile is well–adapted to this faecal milieu. Using our novel approach we have shown that interaction with FW causes fundamental changes in C. difficile biology that will lead to increased disease transmissibility.
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46
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Davidson P, Eutsey R, Redler B, Hiller NL, Laub MT, Durand D. Flexibility and constraint: Evolutionary remodeling of the sporulation initiation pathway in Firmicutes. PLoS Genet 2018; 14:e1007470. [PMID: 30212463 PMCID: PMC6136694 DOI: 10.1371/journal.pgen.1007470] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2017] [Accepted: 06/04/2018] [Indexed: 12/16/2022] Open
Abstract
The evolution of signal transduction pathways is constrained by the requirements of signal fidelity, yet flexibility is necessary to allow pathway remodeling in response to environmental challenges. A detailed understanding of how flexibility and constraint shape bacterial two component signaling systems is emerging, but how new signal transduction architectures arise remains unclear. Here, we investigate pathway remodeling using the Firmicute sporulation initiation (Spo0) pathway as a model. The present-day Spo0 pathways in Bacilli and Clostridia share common ancestry, but possess different architectures. In Clostridium acetobutylicum, sensor kinases directly phosphorylate Spo0A, the master regulator of sporulation. In Bacillus subtilis, Spo0A is activated via a four-protein phosphorelay. The current view favors an ancestral direct phosphorylation architecture, with the phosphorelay emerging in the Bacillar lineage. Our results reject this hypothesis. Our analysis of 84 broadly distributed Firmicute genomes predicts phosphorelays in numerous Clostridia, contrary to the expectation that the Spo0 phosphorelay is unique to Bacilli. Our experimental verification of a functional Spo0 phosphorelay encoded by Desulfotomaculum acetoxidans (Class Clostridia) further supports functional phosphorelays in Clostridia, which strongly suggests that the ancestral Spo0 pathway was a phosphorelay. Cross complementation assays between Bacillar and Clostridial phosphorelays demonstrate conservation of interaction specificity since their divergence over 2.7 BYA. Further, the distribution of direct phosphorylation Spo0 pathways is patchy, suggesting multiple, independent instances of remodeling from phosphorelay to direct phosphorylation. We provide evidence that these transitions are likely the result of changes in sporulation kinase specificity or acquisition of a sensor kinase with specificity for Spo0A, which is remarkably conserved in both architectures. We conclude that flexible encoding of interaction specificity, a phenotype that is only intermittently essential, and the recruitment of kinases to recognize novel environmental signals resulted in a consistent and repeated pattern of remodeling of the Spo0 pathway. Survival in a changing world requires signal transduction circuitry that can evolve to sense and respond to new environmental challenges. The Firmicute sporulation initiation (Spo0) pathway is a compelling example of a pathway with a circuit diagram that has changed over the course of evolution. In Clostridium acetobutylicum, a sensor kinase directly activates the master regulator of sporulation, Spo0A. In Bacillus subtilis, Spo0A is activated indirectly via a four-protein phosphorelay. These early observations suggested that the ancestral Spo0A was directly phosphorylated by a kinase in the earliest spore-former and that the Spo0 phosphorelay arose later in Bacilli via gain of additional proteins and interactions. Our analysis, based on a much larger set of genomes, surprisingly reveals phosphorelays, not only in Bacilli, but in many Clostridia. These findings support a model wherein sporulation was initiated by a Spo0 phosphorelay in the ancestral spore-former and the direct phosphorylation Spo0 pathways, which are observed in distinct sets of Clostridial taxa, are the result of convergent, reductive evolution. Further, our evidence suggests that these remodeling events were mediated by changes in kinase specificity, implicating flexible pathway remodeling, potentially combined with the recruitment of kinases, in Spo0 pathway evolution.
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Affiliation(s)
- Philip Davidson
- Department of Biological Sciences, Carnegie Mellon University, Pittsburgh, Pennsylvania, United States of America
| | - Rory Eutsey
- Department of Biological Sciences, Carnegie Mellon University, Pittsburgh, Pennsylvania, United States of America
| | - Brendan Redler
- Department of Biological Sciences, Carnegie Mellon University, Pittsburgh, Pennsylvania, United States of America
| | - N. Luisa Hiller
- Department of Biological Sciences, Carnegie Mellon University, Pittsburgh, Pennsylvania, United States of America
- Center of Excellence in Biofilm Research, Allegheny Health Network, Pittsburgh, Pennsylvania, United States of America
| | - Michael T. Laub
- Department of Biology, Massachusetts Institute of Technology, Cambridge, Massachusetts, United States of America
- Howard Hughes Medical Institute, Massachusetts Institute of Technology, Cambridge, Massachusetts, United States of America
| | - Dannie Durand
- Department of Biological Sciences, Carnegie Mellon University, Pittsburgh, Pennsylvania, United States of America
- Department of Computer Science, Carnegie Mellon University, Pittsburgh, Pennsylvania, United States of America
- * E-mail:
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Grześkowiak Ł, Riedmüller J, de Thomasson H, Bordessoule S, Seyboldt C, Zentek J, Vahjen W. Porcine and bovine Clostridium difficile ribotype 078 isolates demonstrate similar growth and toxigenic properties. Int Microbiol 2018; 21:215-221. [PMID: 30810901 DOI: 10.1007/s10123-018-0018-x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2018] [Revised: 06/28/2018] [Accepted: 06/29/2018] [Indexed: 02/08/2023]
Abstract
Clostridioides (C.) difficile are found in cows, pigs and poultry suggesting that this pathogen is present and more importantly animals could act as a reservoir, via food or environment, of human C. difficile infection. Molecular methods together with phenotypical characterisation bring integrated and important tools to describe diversity and nature of bacteria including C. difficile. Moreover, similar or identical C. difficile types are found in different farm animals. This study aimed to phenotypically characterise C. difficile isolates belonging to ribotype 078 and to identify differences such as growth and toxicity between porcine and bovine isolates. C. difficile isolates were assessed for the growth behaviour (turbidimetry), metabolic potential (Biolog AN) and toxin production (ELISA method) in vitro. The concentration of released either toxin A (TcdA) or toxin B (TcdB) varied greatly between the isolates tested; however, it did not differ between the porcine and bovine ribotypes. Also, the TcdA/TcdB ratio of the isolates did not show a difference either. The most common metabolised substrates were pyruvic acid followed by α-ketobutyric acid. The results show that both porcine and bovine C. difficile RT 078 share similar phenotypical characteristics including growth and production of toxins. The findings may help understand the virulence of C. difficile RT 078 in porcine and bovine species.
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Affiliation(s)
- Łukasz Grześkowiak
- Freie Universität Berlin, Institute of Animal Nutrition, Königin-Luise-Str. 49, 14195, Berlin, Germany.
| | - Jonathan Riedmüller
- Freie Universität Berlin, Institute of Animal Nutrition, Königin-Luise-Str. 49, 14195, Berlin, Germany
| | | | - Solenne Bordessoule
- Ecole de Biologie Industrielle, 49 Avenue des Genottes, 95800, Cergy, France
| | - Christian Seyboldt
- Institute of Bacterial Infections and Zoonoses, Friedrich-Loeffler-Institut, Naumburger Straße 96a, 07743, Jena, Germany
| | - Jürgen Zentek
- Freie Universität Berlin, Institute of Animal Nutrition, Königin-Luise-Str. 49, 14195, Berlin, Germany
| | - Wilfried Vahjen
- Freie Universität Berlin, Institute of Animal Nutrition, Königin-Luise-Str. 49, 14195, Berlin, Germany
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Thanissery R, Zeng D, Doyle RG, Theriot CM. A Small Molecule-Screening Pipeline to Evaluate the Therapeutic Potential of 2-Aminoimidazole Molecules Against Clostridium difficile. Front Microbiol 2018; 9:1206. [PMID: 29928268 PMCID: PMC5997789 DOI: 10.3389/fmicb.2018.01206] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2018] [Accepted: 05/17/2018] [Indexed: 12/19/2022] Open
Abstract
Antibiotics are considered to be the first line of treatment for mild to moderately severe Clostridium difficile infection (CDI) in humans. However, antibiotics are also risk factors for CDI as they decrease colonization resistance against C. difficile by altering the gut microbiota and metabolome. Finding compounds that selectively inhibit different stages of the C. difficile life cycle, while sparing the indigenous gut microbiota is important for the development of alternatives to standard antibiotic treatment. 2-aminoimidazole (2-AI) molecules are known to disrupt bacterial protection mechanisms in antibiotic resistant bacteria such as Pseudomonas aeruginosa, Acinetobacter baumannii, and Staphylococcus aureus, but are yet to be evaluated against C. difficile. A comprehensive small molecule-screening pipeline was developed to investigate how novel small molecules affect different stages of the C. difficile life cycle (growth, toxin, and sporulation) in vitro, and a library of commensal bacteria that are associated with colonization resistance against C. difficile. The initial screening tested the efficacy of eleven 2-AI molecules (compound 1 through 11) against C. difficile R20291 compared to a vancomycin (2 μg/ml) control. Molecules were selected for their ability to inhibit C. difficile growth, toxin activity, and sporulation. Further testing included growth inhibition of other C. difficile strains (CD196, M68, CF5, 630, BI9, M120) belonging to distinct PCR ribotypes, and a commensal panel (Bacteroides fragilis, B. thetaiotaomicron, C. scindens, C. hylemonae, Lactobacillus acidophilus, L. gasseri, Escherichia coli, B. longum subsp. infantis). Three molecules compound 1 and 2, and 3 were microbicidal, whereas compounds 4, 7, 9, and 11 inhibited toxin activity without affecting the growth of C. difficile strains and the commensal microbiota. The antimicrobial and anti-toxin effects of 2-AI molecules need to be further characterized for mode of action and validated in a mouse model of CDI.
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Affiliation(s)
- Rajani Thanissery
- Department of Population Health and Pathobiology, College of Veterinary Medicine, North Carolina State University, Raleigh, NC, United States
| | - Daina Zeng
- Agile Sciences, Inc., Raleigh, NC, United States
| | - Raul G Doyle
- Agile Sciences, Inc., Raleigh, NC, United States
| | - Casey M Theriot
- Department of Population Health and Pathobiology, College of Veterinary Medicine, North Carolina State University, Raleigh, NC, United States
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Blanco N, Walk S, Malani AN, Rickard A, Benn M, Eisenberg M, Zhang M, Foxman B. Clostridium difficile shows no trade-off between toxin and spore production within the human host. J Med Microbiol 2018. [PMID: 29533173 DOI: 10.1099/jmm.0.000719] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
PURPOSE This study aimed to describe the correlation between Clostridium difficile spore and toxin levels within the human host. In addition, we assessed whether overgrowth of Candida albicans modified this association. METHODOLOGY We measured toxin, spore and Candida albicans levels among 200 successively collected stool samples that tested positive for C. difficile, and PCR ribotyped these C. difficile isolates. Analysis of variance and linear regression were used to test the association between spore and toxin levels. Kruskal-Wallis tests and t-tests were used to compare the association between spore or toxin levels and host, specimen, or pathogen characteristics. RESULTS C. difficile toxin and spore levels were positively associated (P<0.001); this association did not vary significantly with C. albicans overgrowth [≥5 logs of C. albicans colony-forming units (c.f.u.) g-1]. However, ribotypes 027 and 078-126 were significantly associated with higher levels of toxin and spores, and C. albicans overgrowth. CONCLUSION The strong positive association observed between in vivo levels of C. difficile toxin and spores suggests that patients with more severe C. difficile infections may have increased spore production, enhancing C. difficile transmission. Although, on average, spore levels were higher in toxin-positive samples than in toxin-negative/PCR-positive samples, spores were found in almost all toxin-negative samples. The ubiquity of spore production among toxin-negative and formed stool samples emphasizes the importance of following infection prevention and control measures for all C. difficile-positive patients during their entire hospital stay.
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Affiliation(s)
- Natalia Blanco
- Department of Epidemiology, School of Public Health, University of Michigan, Ann Arbor, Michigan, USA
| | - Seth Walk
- Department of Microbiology and Immunology, College of Letters & Science, Montana State, Bozeman, Montana, USA
| | - Anurag N Malani
- Department of Infection Prevention and Control, Department of Internal Medicine, Division of Infectious Diseases, St Joseph Mercy Health System, Ann Arbor, Michigan, USA
| | - Alexander Rickard
- Department of Epidemiology, School of Public Health, University of Michigan, Ann Arbor, Michigan, USA
| | - Michele Benn
- Department of Pathology, Microbiology Laboratory, St Joseph Mercy Health System, Ann Arbor, Michigan, USA
| | - Marisa Eisenberg
- Department of Epidemiology, School of Public Health, University of Michigan, Ann Arbor, Michigan, USA
| | - Min Zhang
- Department of Infection Prevention and Control, Department of Internal Medicine, Division of Infectious Diseases, St Joseph Mercy Health System, Ann Arbor, Michigan, USA.,Department of Biostatistics, School of Public Health, University of Michigan, Ann Arbor, Michigan, USA
| | - Betsy Foxman
- Department of Epidemiology, School of Public Health, University of Michigan, Ann Arbor, Michigan, USA
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Abstract
Clostridium difficile is the primary cause of nosocomial diarrhea and pseudomembranous colitis. It produces dormant spores, which serve as an infectious vehicle responsible for transmission of the disease and persistence of the organism in the environment. In Bacillus subtilis, the sin locus coding SinR (113 aa) and SinI (57 aa) is responsible for sporulation inhibition. In B. subtilis, SinR mainly acts as a repressor of its target genes to control sporulation, biofilm formation, and autolysis. SinI is an inhibitor of SinR, so their interaction determines whether SinR can inhibit its target gene expression. The C. difficile genome carries two sinR homologs in the operon that we named sinR and sinR’, coding for SinR (112 aa) and SinR’ (105 aa), respectively. In this study, we constructed and characterized sin locus mutants in two different C. difficile strains R20291 and JIR8094, to decipher the locus’s role in C. difficile physiology. Transcriptome analysis of the sinRR’ mutants revealed their pleiotropic roles in controlling several pathways including sporulation, toxin production, and motility in C. difficile. Through various genetic and biochemical experiments, we have shown that SinR can regulate transcription of key regulators in these pathways, which includes sigD, spo0A, and codY. We have found that SinR’ acts as an antagonist to SinR by blocking its repressor activity. Using a hamster model, we have also demonstrated that the sin locus is needed for successful C. difficile infection. This study reveals the sin locus as a central link that connects the gene regulatory networks of sporulation, toxin production, and motility; three key pathways that are important for C. difficile pathogenesis. In Bacillus subtilis, sporulation, competence and biofilm formation are regulated by a pleiotropic regulator called SinR. Two sinR homologs are present in C. difficile genome as an operon and henceforth labeled as sinR and sinR’. Our detailed investigation revealed that in C. difficile, the SinR and SinR’ are key master regulators needed for the regulation of several pathways including sporulation, toxin production, and motility.
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Affiliation(s)
| | - Junjun Ou
- Department of Agronomy, Kansas State University, Manhattan, KS, United Sates of America
| | - Bruno Dupuy
- Laboratoire Pathogénese des Bactéries Anaérobies, Institut Pasteur, Paris, France
- Université Paris Diderot, Sorbonne Paris Cité, Paris, France
| | - Revathi Govind
- Division of Biology, Kansas State University, Manhattan, KS, United Sates of America
- * E-mail:
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