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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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2
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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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3
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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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4
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Marshall A, McGrath JW, Mitchell M, Fanning S, McMullan G. One size does not fit all - Trehalose metabolism by Clostridioides difficile is variable across the five phylogenetic lineages. Microb Genom 2023; 9:001110. [PMID: 37768179 PMCID: PMC10569727 DOI: 10.1099/mgen.0.001110] [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: 05/25/2023] [Accepted: 09/19/2023] [Indexed: 09/29/2023] Open
Abstract
Clostridioides difficile, the leading cause of antibiotic-associated diarrhoea worldwide, is a genetically diverse species which can metabolise a number of nutrient sources upon colonising a dysbiotic gut environment. Trehalose, a disaccharide sugar consisting of two glucose molecules bonded by an α 1,1-glycosidic bond, has been hypothesised to be involved in the emergence of C. difficile hypervirulence due to its increased utilisation by the RT027 and RT078 strains. Here, growth in trehalose as the sole carbon source was shown to be non-uniform across representative C. difficile strains, even though the genes for its metabolism were induced. Growth in trehalose reduced the expression of genes associated with toxin production and sporulation in the C. difficile R20291 (RT027) and M120 (RT078) strains in vitro, suggesting an inhibitory effect on virulence factors. Interestingly, the R20291 TreR transcriptional regulatory protein appeared to possess an activator function as its DNA-binding ability was increased in the presence of its effector, trehalose-6-phosphate. Using RNA-sequencing analysis, we report the identification of a putative trehalose metabolism pathway which is induced during growth in trehalose: this has not been previously described within the C. difficile species. These data demonstrate the metabolic diversity exhibited by C. difficile which warrants further investigation to elucidate the molecular basis of trehalose metabolism within this important gut pathogen.
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Affiliation(s)
- Andrew Marshall
- School of Biological Sciences, Queen’s University Belfast, 19 Chlorine Gardens, Belfast, BT9 5DL, UK
| | - John W. McGrath
- School of Biological Sciences, Queen’s University Belfast, 19 Chlorine Gardens, Belfast, BT9 5DL, UK
| | - Molly Mitchell
- University College Dublin-Centre for Food Safety University College Dublin, Dublin, Ireland
| | - Séamus Fanning
- University College Dublin-Centre for Food Safety University College Dublin, Dublin, Ireland
| | - Geoff McMullan
- School of Biological Sciences, Queen’s University Belfast, 19 Chlorine Gardens, Belfast, BT9 5DL, UK
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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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6
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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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Krishnakumar R, Ruffing AM. OperonSEQer: A set of machine-learning algorithms with threshold voting for detection of operon pairs using short-read RNA-sequencing data. PLoS Comput Biol 2022; 18:e1009731. [PMID: 34986143 PMCID: PMC8765615 DOI: 10.1371/journal.pcbi.1009731] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2021] [Revised: 01/18/2022] [Accepted: 12/07/2021] [Indexed: 11/19/2022] Open
Abstract
Operon prediction in prokaryotes is critical not only for understanding the regulation of endogenous gene expression, but also for exogenous targeting of genes using newly developed tools such as CRISPR-based gene modulation. A number of methods have used transcriptomics data to predict operons, based on the premise that contiguous genes in an operon will be expressed at similar levels. While promising results have been observed using these methods, most of them do not address uncertainty caused by technical variability between experiments, which is especially relevant when the amount of data available is small. In addition, many existing methods do not provide the flexibility to determine the stringency with which genes should be evaluated for being in an operon pair. We present OperonSEQer, a set of machine learning algorithms that uses the statistic and p-value from a non-parametric analysis of variance test (Kruskal-Wallis) to determine the likelihood that two adjacent genes are expressed from the same RNA molecule. We implement a voting system to allow users to choose the stringency of operon calls depending on whether your priority is high recall or high specificity. In addition, we provide the code so that users can retrain the algorithm and re-establish hyperparameters based on any data they choose, allowing for this method to be expanded as additional data is generated. We show that our approach detects operon pairs that are missed by current methods by comparing our predictions to publicly available long-read sequencing data. OperonSEQer therefore improves on existing methods in terms of accuracy, flexibility, and adaptability. Bacteria and archaea, single-cell organisms collectively known as prokaryotes, live in all imaginable environments and comprise the majority of living organisms on this planet. Prokaryotes play a critical role in the homeostasis of multicellular organisms (such as animals and plants) and ecosystems. In addition, bacteria can be pathogenic and cause a variety of diseases in these same hosts and ecosystems. In short, understanding the biology and molecular functions of bacteria and archaea and devising mechanisms to engineer and optimize their properties are critical scientific endeavors with significant implications in healthcare, agriculture, manufacturing, and climate science among others. One major molecular difference between unicellular and multicellular organisms is the way they express genes–multicellular organisms make individual RNA molecules for each gene while, prokaryotes express operons (i.e., a group of genes coding functionally related proteins) in contiguous polycistronic RNA molecules. Understanding which genes exist within operons is critical for elucidating basic biology and for engineering organisms. In this work, we use a combination of statistical and machine learning-based methods to use next-generation sequencing data to predict operon structure across a range of prokaryotes. Our method provides an easily implemented, robust, accurate, and flexible way to determine operon structure in an organism-agnostic manner using readily available data.
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Affiliation(s)
- Raga Krishnakumar
- Systems Biology Department, Sandia National Laboratories, Livermore, California, United States of America
- * E-mail:
| | - Anne M. Ruffing
- Molecular and Microbiology Department, Sandia National Laboratories, Albuquerque, New Mexico, United States of America
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8
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Dhungel BA, Govind R. Phase-variable expression of pdcB, a phosphodiesterase, influences sporulation in Clostridioides difficile. Mol Microbiol 2021; 116:1347-1360. [PMID: 34606654 DOI: 10.1111/mmi.14828] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2021] [Revised: 09/30/2021] [Accepted: 10/01/2021] [Indexed: 02/07/2023]
Abstract
Clostridioides difficile is the causative agent of antibiotic-associated diarrhea and is the leading cause of nosocomial infection in developed countries. An increasing number of C. difficile infections are attributed to epidemic strains that produce more toxins and spores. C. difficile spores are the major factor for the transmission and persistence of the organism. Previous studies have identified global regulators that influence sporulation in C. difficile. This study discovers that PdcB, a phosphodiesterase, enhances sporulation in C. difficile strain UK1. Through genetic and biochemical assays, we show that phase-variable expression of pdcB results in hypo- and hyper-sporulation phenotypes. In the "ON" orientation, the identified promotor is in the right orientation to drive the expression of pdcB. Production of the PdcB phosphodiesterase reduces the intracellular cyclic-di-GMP (c-di-GMP) concentration, resulting in a hyper-sporulation phenotype. Loss of PdcB due to the pdcB promoter being in the OFF orientation or mutation of pdcB results in increased c-di-GMP levels and a hypo-sporulation phenotype. Additionally, we demonstrate that CodY binds to the upstream region of pdcB. DNA inversion reorients the CodY binding site so that in the OFF orientation, CodY binds a site that is upstream of the pdcB promoter and can further repress gene expression.
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Affiliation(s)
| | - Revathi Govind
- Division of Biology, Kansas State University, Manhattan, Kansas, USA
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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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10
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Systematic Evaluation of Parameters Important for Production of Native Toxin A and Toxin B from Clostridioides difficile. Toxins (Basel) 2021; 13:toxins13040240. [PMID: 33801738 PMCID: PMC8066640 DOI: 10.3390/toxins13040240] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2021] [Revised: 03/19/2021] [Accepted: 03/25/2021] [Indexed: 12/26/2022] Open
Abstract
In the attempt to improve the purification yield of native toxin A (TcdA) and toxin B (TcdB) from Clostridioides difficile (C. difficile), we systematically evaluated culture parameters for their influence on toxin production. In this study, we showed that culturing C. difficile in a tryptone-yeast extract medium buffered in PBS (pH 7.5) that contained 5 mM ZnCl2 and 10 mM glucose supported the highest TcdB production, measured by the sandwich ELISA. These culture conditions were scalable into 5 L and 15 L dialysis tube cultures, and we were able to reach a TcdB concentration of 29.5 µg/mL of culture. Furthermore, we established a purification protocol for TcdA and TcdB using FPLC column chromatography, reaching purities of >99% for both toxins with a yield around 25% relative to the starting material. Finally, by screening the melting temperatures of TcdA and TcdB in various buffer conditions using differential scanning fluorimetry, we found optimal conditions for improving the protein stability during storage. The results of this study present a complete protocol for obtaining high amounts of highly purified native TcdA and TcdB from C. difficile.
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11
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Castro-Córdova P, Mora-Uribe P, Reyes-Ramírez R, Cofré-Araneda G, Orozco-Aguilar J, Brito-Silva C, Mendoza-León MJ, Kuehne SA, Minton NP, Pizarro-Guajardo M, Paredes-Sabja D. Entry of spores into intestinal epithelial cells contributes to recurrence of Clostridioides difficile infection. Nat Commun 2021; 12:1140. [PMID: 33602902 PMCID: PMC7893008 DOI: 10.1038/s41467-021-21355-5] [Citation(s) in RCA: 52] [Impact Index Per Article: 17.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2020] [Accepted: 01/19/2021] [Indexed: 02/06/2023] Open
Abstract
Clostridioides difficile spores produced during infection are important for the recurrence of the disease. Here, we show that C. difficile spores gain entry into the intestinal mucosa via pathways dependent on host fibronectin-α5β1 and vitronectin-αvβ1. The exosporium protein BclA3, on the spore surface, is required for both entry pathways. Deletion of the bclA3 gene in C. difficile, or pharmacological inhibition of endocytosis using nystatin, leads to reduced entry into the intestinal mucosa and reduced recurrence of the disease in a mouse model. Our findings indicate that C. difficile spore entry into the intestinal barrier can contribute to spore persistence and infection recurrence, and suggest potential avenues for new therapies.
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Affiliation(s)
- Pablo Castro-Córdova
- Microbiota-Host Interactions and Clostridia Research Group, Facultad de Ciencias de la Vida, Universidad Andrés Bello, Santiago, Chile
- ANID - Millennium Science Initiative Program - Millennium Nucleus in the Biology of the Intestinal Microbiota, Santiago, Chile
| | - Paola Mora-Uribe
- Microbiota-Host Interactions and Clostridia Research Group, Facultad de Ciencias de la Vida, Universidad Andrés Bello, Santiago, Chile
| | - Rodrigo Reyes-Ramírez
- Microbiota-Host Interactions and Clostridia Research Group, Facultad de Ciencias de la Vida, Universidad Andrés Bello, Santiago, Chile
- ANID - Millennium Science Initiative Program - Millennium Nucleus in the Biology of the Intestinal Microbiota, Santiago, Chile
| | - Glenda Cofré-Araneda
- Microbiota-Host Interactions and Clostridia Research Group, Facultad de Ciencias de la Vida, Universidad Andrés Bello, Santiago, Chile
| | - Josué Orozco-Aguilar
- Microbiota-Host Interactions and Clostridia Research Group, Facultad de Ciencias de la Vida, Universidad Andrés Bello, Santiago, Chile
- ANID - Millennium Science Initiative Program - Millennium Nucleus in the Biology of the Intestinal Microbiota, Santiago, Chile
| | - Christian Brito-Silva
- Microbiota-Host Interactions and Clostridia Research Group, Facultad de Ciencias de la Vida, Universidad Andrés Bello, Santiago, Chile
- ANID - Millennium Science Initiative Program - Millennium Nucleus in the Biology of the Intestinal Microbiota, Santiago, Chile
| | - María José Mendoza-León
- Microbiota-Host Interactions and Clostridia Research Group, Facultad de Ciencias de la Vida, Universidad Andrés Bello, Santiago, Chile
- ANID - Millennium Science Initiative Program - Millennium Nucleus in the Biology of the Intestinal Microbiota, Santiago, Chile
| | - Sarah A Kuehne
- School of Dentistry and Institute for Microbiology and Infection, University of Birmingham, Birmingham, UK
| | - Nigel P Minton
- BBSRC/EPSRC Synthetic Biology Research Centre, School of Life Sciences, Centre for Biomolecular Sciences, The University of Nottingham, Nottingham, UK
| | - Marjorie Pizarro-Guajardo
- Microbiota-Host Interactions and Clostridia Research Group, Facultad de Ciencias de la Vida, Universidad Andrés Bello, Santiago, Chile
- ANID - Millennium Science Initiative Program - Millennium Nucleus in the Biology of the Intestinal Microbiota, Santiago, Chile
- Department of Biology, Texas A&M University, College Station, TX, USA
| | - Daniel Paredes-Sabja
- Microbiota-Host Interactions and Clostridia Research Group, Facultad de Ciencias de la Vida, Universidad Andrés Bello, Santiago, Chile.
- ANID - Millennium Science Initiative Program - Millennium Nucleus in the Biology of the Intestinal Microbiota, Santiago, Chile.
- Department of Biology, Texas A&M University, College Station, TX, USA.
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12
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Clostridioides difficile exploits toxin-mediated inflammation to alter the host nutritional landscape and exclude competitors from the gut microbiota. Nat Commun 2021; 12:462. [PMID: 33469019 PMCID: PMC7815924 DOI: 10.1038/s41467-020-20746-4] [Citation(s) in RCA: 89] [Impact Index Per Article: 29.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2020] [Accepted: 12/17/2020] [Indexed: 01/04/2023] Open
Abstract
Clostridioides difficile is a bacterial pathogen that causes a range of clinical disease from mild to moderate diarrhea, pseudomembranous colitis, and toxic megacolon. Typically, C. difficile infections (CDIs) occur after antibiotic treatment, which alters the gut microbiota, decreasing colonization resistance against C. difficile. Disease is mediated by two large toxins and the expression of their genes is induced upon nutrient depletion via the alternative sigma factor TcdR. Here, we use tcdR mutants in two strains of C. difficile and omics to investigate how toxin-induced inflammation alters C. difficile metabolism, tissue gene expression and the gut microbiota, and to determine how inflammation by the host may be beneficial to C. difficile. We show that C. difficile metabolism is significantly different in the face of inflammation, with changes in many carbohydrate and amino acid uptake and utilization pathways. Host gene expression signatures suggest that degradation of collagen and other components of the extracellular matrix by matrix metalloproteinases is a major source of peptides and amino acids that supports C. difficile growth in vivo. Lastly, the inflammation induced by C. difficile toxin activity alters the gut microbiota, excluding members from the genus Bacteroides that are able to utilize the same essential nutrients released from collagen degradation. The effects of antibiotics on the gut microbiota can lead to enhanced colonization of Clostridioides difficile (C. difficile) and toxin-mediated pathogenesis. Here, using defined toxin-mutant strains and a murine model, the authors provide insights into how toxin-induced inflammation alters C. difficile metabolism, host tissue gene expression and gut microbiota, together influencing a beneficial niche for infection.
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13
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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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The Impact of pH on Clostridioides difficile Sporulation and Physiology. Appl Environ Microbiol 2020; 86:AEM.02706-19. [PMID: 31811041 DOI: 10.1128/aem.02706-19] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2019] [Accepted: 12/03/2019] [Indexed: 12/18/2022] Open
Abstract
Clostridioides difficile is a pathogenic bacterium that infects the human colon to cause diarrheal disease. Growth of the bacterium is known to be dependent on certain bile acids, oxygen levels, and nutrient availability in the intestine, but how the environmental pH can influence C. difficile is mostly unknown. Previous studies indicated that C. difficile modulates the intestinal pH, and prospective cohort studies have found a strong association between a more alkaline fecal pH and C. difficile infection. Based on these data, we hypothesized that C. difficile physiology can be affected by various pH conditions. In this study, we investigated the impact of a range of pH conditions on C. difficile to assess potential effects on growth, sporulation, motility, and toxin production in the strains 630Δerm and R20291. We observed pH-dependent differences in sporulation rate, spore morphology, and viability. Sporulation frequency was lowest under acidic conditions, and differences in cell morphology were apparent at low pH. In alkaline environments, C. difficile sporulation was greater for strain 630Δerm, whereas R20291 produced relatively high levels of spores in a broad range of pH conditions. Rapid changes in pH during exponential growth impacted sporulation similarly among the strains. Furthermore, we observed an increase in C. difficile motility with increases in pH, and strain-dependent differences in toxin production under acidic conditions. The data demonstrate that pH is an important parameter that affects C. difficile physiology and may reveal relevant insights into the growth and dissemination of this pathogen.IMPORTANCE Clostridioides difficile is an anaerobic bacterium that causes gastrointestinal disease. C. difficile forms dormant spores which can survive harsh environmental conditions, allowing their spread to new hosts. In this study, we determine how intestinally relevant pH conditions impact C. difficile physiology in the two divergent strains, 630Δerm and R20291. Our data demonstrate that low pH conditions reduce C. difficile growth, sporulation, and motility. However, toxin production and spore morphology were differentially impacted in the two strains at low pH. In addition, we observed that alkaline environments reduce C. difficile growth, but increase cell motility. When pH was adjusted rapidly during growth, we observed similar impacts on both strains. This study provides new insights into the phenotypic diversity of C. difficile grown under diverse pH conditions present in the intestinal tract, and demonstrates similarities and differences in the pH responses of different C. difficile isolates.
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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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Chen KY, Rathod J, Chiu YC, Chen JW, Tsai PJ, Huang IH. The Transcriptional Regulator Lrp Contributes to Toxin Expression, Sporulation, and Swimming Motility in Clostridium difficile. Front Cell Infect Microbiol 2019; 9:356. [PMID: 31681632 PMCID: PMC6811523 DOI: 10.3389/fcimb.2019.00356] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2019] [Accepted: 10/02/2019] [Indexed: 12/17/2022] Open
Abstract
Clostridium difficile is a Gram-positive, spore-forming bacterium, and major cause of nosocomial diarrhea. Related studies have identified numerous factors that influence virulence traits such as the production of the two primary toxins, toxin A (TcdA) and toxin B (TcdB), as well as sporulation, motility, and biofilm formation. However, multiple putative transcriptional regulators are reportedly encoded in the genome, and additional factors are likely involved in virulence regulation. Although the leucine-responsive regulatory protein (Lrp) has been studied extensively in Gram-negative bacteria, little is known about its function in Gram-positive bacteria, although homologs have been identified in the genome. This study revealed that disruption of the lone lrp homolog in C. difficile decelerated growth under nutrient-limiting conditions, increased TcdA and TcdB production. Lrp was also found to negatively regulate sporulation while positively regulate swimming motility in strain R20291, but not in strain 630. The C. difficile Lrp appeared to function through transcriptional repression or activation. In addition, the lrp mutant was relatively virulent in a mouse model of infection. The results of this study collectively demonstrated that Lrp has broad regulatory function in C. difficile toxin expression, sporulation, motility, and pathogenesis.
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Affiliation(s)
- Kuan-Yu Chen
- Department of Microbiology and Immunology, College of Medicine, National Cheng Kung University, Tainan, Taiwan
| | - Jagat Rathod
- Department of Earth Sciences, National Cheng Kung University, Tainan, Taiwan
| | - Yi-Ching Chiu
- Department of Microbiology and Immunology, College of Medicine, National Cheng Kung University, Tainan, Taiwan
| | - Jenn-Wei Chen
- Department of Microbiology and Immunology, College of Medicine, National Cheng Kung University, Tainan, Taiwan.,Center of Infectious Disease and Signaling Research, National Cheng Kung University, Tainan, Taiwan
| | - Pei-Jane Tsai
- Center of Infectious Disease and Signaling Research, National Cheng Kung University, Tainan, Taiwan.,Department of Medical Laboratory Science and Biotechnology, College of Medicine, National Cheng Kung University, Tainan, Taiwan
| | - I-Hsiu Huang
- Department of Microbiology and Immunology, College of Medicine, National Cheng Kung University, Tainan, Taiwan.,Center of Infectious Disease and Signaling Research, National Cheng Kung University, Tainan, Taiwan
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Ciftci Y, Girinathan BP, Dhungel BA, Hasan MK, Govind R. Clostridioides difficile SinR' regulates toxin, sporulation and motility through protein-protein interaction with SinR. Anaerobe 2019; 59:1-7. [PMID: 31077800 PMCID: PMC6785386 DOI: 10.1016/j.anaerobe.2019.05.002] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2018] [Revised: 04/10/2019] [Accepted: 05/07/2019] [Indexed: 12/18/2022]
Abstract
Clostridioides difficile is a Gram-positive, anaerobic bacterium. It is known that C. difficile is one of the major causes of antibiotic associated diarrhea. The enhanced antibiotic resistance observed in C. difficile is the result of highly resistant spores produced by the bacterium. In Bacillus subtilis, the sin operon is involved in sporulation inhibition. Two proteins coded within this operon, SinR and SinI, have an antagonistic relationship; SinR acts as an inhibitor to sporulation whereas SinI represses the activity of SinR, thus allowing the bacterium to sporulate. In a previous study, we examined the sin locus in C. difficile and named the two genes associated with this operon sinR and sinR', analogous to sinR and sinI in B. subtilis, respectively. We have shown that SinR and SinR' have pleiotropic roles in pathogenesis pathways and interact antagonistically with each other. Unlike B. subtilis SinI, SinR' in C. difficile carries two domains: the HTH domain and the Multimerization Domain (MD). In this study, we first performed a GST Pull-down experiment to determine the domain within SinR' that interacts with SinR. Second, the effect of these two domains on three phenotypes; sporulation, motility, and toxin production was examined. The findings of this study confirmed the prediction that the Multimerization Domain (MD) of SinR' is responsible for the interaction between SinR and SinR'. It was also discovered that SinR' regulates sporulation, toxin production and motility primarily by inhibiting SinR activity through the Multimerization Domain (MD).
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Affiliation(s)
- Yusuf Ciftci
- Division of Biology, Kansas State University, Manhattan, KS, USA
| | - Brintha Parasumanna Girinathan
- Division of Biology, Kansas State University, Manhattan, KS, USA; Department of Pathology, Harvard Medical School, Boston, MA, USA
| | | | - Md Kamrul Hasan
- Division of Biology, Kansas State University, Manhattan, KS, USA
| | - Revathi Govind
- Division of Biology, Kansas State University, Manhattan, KS, USA.
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Surface morphology differences in Clostridium difficile spores, based on different strains and methods of purification. Anaerobe 2019; 61:102078. [PMID: 31344453 DOI: 10.1016/j.anaerobe.2019.102078] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2019] [Revised: 07/18/2019] [Accepted: 07/19/2019] [Indexed: 11/21/2022]
Abstract
Infections linked to Clostridium difficile are a significant cause of suffering. In hospitals, the organism is primarily acquired through the faecal-oral route as spores excreted by infected patients contaminate the healthcare environment. We previously reported that members of the C. difficile group varied widely in their ability to adhere to stainless steel and proposed that these differences were a consequence of variations in spore architecture. In this study of clinical isolates and spore coat protein mutants of C. difficile we identified three distinct spore surfaces morphotypes; smooth, bag-like and "pineapple-like" using scanning electron microscopy (SEM). The frequency of each morphotype in a spore population derived from a single isolate varied depending on the host strain and the method used to produce and purify the spores. Our results suggest that the inclusion of a sonication step in the purification process had a marked effect on spore structure. In an attempt to link differences in spore appearance with key structural spore proteins we compared the morphology of spores of CD630 to those produced by CD630 variants lacking either CotE or BclA. While SEM images revealed no obvious structural differences between CD630 and its mutants we did observe significant differences (p < 0.001) in relative hydrophobicity suggesting that modifications had occurred but not at a level to be detectable by SEM. In conclusion, we observed significant variation in the spore morphology of clinical isolates of C. difficile due in part to the methods used to produce them. Sonication in particular can markedly change spore appearance and properties. The results of this study highlight the importance of adopting "standard" methods when attempting to compare results between studies and to understand the significance of their differences.
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Foulquier C, Huang CN, Nguyen NPT, Thiel A, Wilding-Steel T, Soula J, Yoo M, Ehrenreich A, Meynial-Salles I, Liebl W, Soucaille P. An efficient method for markerless mutant generation by allelic exchange in Clostridium acetobutylicum and Clostridium saccharobutylicum using suicide vectors. BIOTECHNOLOGY FOR BIOFUELS 2019; 12:31. [PMID: 30809274 PMCID: PMC6375146 DOI: 10.1186/s13068-019-1364-4] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 01/09/2019] [Accepted: 01/29/2019] [Indexed: 06/09/2023]
Abstract
BACKGROUND Clostridium acetobutylicum and Clostridium saccharobutylicum are Gram-positive, spore-forming, anaerobic bacterium capable of converting various sugars and polysaccharides into solvents (acetone, butanol, and ethanol). The sequencing of their genomes has prompted new approaches to genetic analysis, functional genomics, and metabolic engineering to develop industrial strains for the production of biofuels and bulk chemicals. RESULTS The method used in this paper to knock-out, knock-in, or edit genes in C. acetobutylicum and C. saccharobutylicum combines an improved electroporation method with the use of (i) restrictionless Δupp (which encodes uracil phosphoribosyl-transferase) strains and (ii) very small suicide vectors containing a markerless deletion/insertion cassette, an antibiotic resistance gene (for the selection of the first crossing-over) and upp (from C. acetobutylicum) for subsequent use as a counterselectable marker with the aid of 5-fluorouracil (5-FU) to promote the second crossing-over. This method was successfully used to both delete genes and edit genes in both C. acetobutylicum and C. saccharobutylicum. Among the edited genes, a mutation in the spo0A gene that abolished solvent formation in C. acetobutylicum was introduced in C. saccharobutylicum and shown to produce the same effect. CONCLUSIONS The method described in this study will be useful for functional genomic studies and for the development of industrial strains for the production of biofuels and bulk chemicals.
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Affiliation(s)
- Celine Foulquier
- LISBP, INSA, University of Toulouse, 135 Avenue de Rangueil, 31077 Toulouse Cedex, France
| | - Ching-Ning Huang
- Chair of Microbiology, Technical University Munchen, Emil-Ramann-Str. 4, 85354 Freising, Germany
| | - Ngoc-Phuong-Thao Nguyen
- LISBP, INSA, University of Toulouse, 135 Avenue de Rangueil, 31077 Toulouse Cedex, France
- Tan Tao University, School of Medicine, University Avenue, Tan Duc e-City, Duc Hoa, Vietnam
| | - Axel Thiel
- LISBP, INSA, University of Toulouse, 135 Avenue de Rangueil, 31077 Toulouse Cedex, France
| | - Tom Wilding-Steel
- LISBP, INSA, University of Toulouse, 135 Avenue de Rangueil, 31077 Toulouse Cedex, France
| | - Julie Soula
- LISBP, INSA, University of Toulouse, 135 Avenue de Rangueil, 31077 Toulouse Cedex, France
| | - Minyeong Yoo
- LISBP, INSA, University of Toulouse, 135 Avenue de Rangueil, 31077 Toulouse Cedex, France
- BBSRC/EPSRC Synthetic Biology Research Centre, School of Life Sciences, Centre for Biomolecular Sciences, University of Nottingham, University Blvd, Nottingham, NG7 2JE UK
| | - Armin Ehrenreich
- Chair of Microbiology, Technical University Munchen, Emil-Ramann-Str. 4, 85354 Freising, Germany
| | | | - Wolfgang Liebl
- Chair of Microbiology, Technical University Munchen, Emil-Ramann-Str. 4, 85354 Freising, Germany
| | - Philippe Soucaille
- LISBP, INSA, University of Toulouse, 135 Avenue de Rangueil, 31077 Toulouse Cedex, France
- BBSRC/EPSRC Synthetic Biology Research Centre, School of Life Sciences, Centre for Biomolecular Sciences, University of Nottingham, University Blvd, Nottingham, NG7 2JE UK
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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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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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Shrestha R, Sorg JA. Hierarchical recognition of amino acid co-germinants during Clostridioides difficile spore germination. Anaerobe 2018; 49:41-47. [PMID: 29221987 PMCID: PMC5844826 DOI: 10.1016/j.anaerobe.2017.12.001] [Citation(s) in RCA: 41] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2017] [Revised: 11/17/2017] [Accepted: 12/03/2017] [Indexed: 12/15/2022]
Abstract
Bile acids are an important signal for germination of Clostridioides difficile spores; however, the bile acid signal alone is not sufficient. Amino acids, such as glycine, are another signal necessary for germination by C. difficile spores. Prior studies on the amino acid signal required for germination have shown that there is a preference for the amino acid used as a signal for germination. Previously we found that d-alanine can function as a co-germinant for C. difficile spores at 37 °C but not at 25 °C. Here, we tested the ability of other amino acids to act as co-germinants with taurocholate (TA) at 37 °C and found that many amino acids previously categorized as non-co-germinants are co-germinants at 37 °C. Based on the EC50 values calculated for two different strains, we found that C. difficile spores recognize different amino acids with varying efficiencies. Using this data, we ranked the amino acids based on their effect on germination and found that in addition to d-alanine, other D-forms of amino acids are also used by C. difficile spores as co-germinants. Among the different types of amino acids, ones with branched chains such as valine, leucine, and isoleucine are the poorest co-germinants. However, glycine is still the most effective amino acid signal for both strains. Our results suggest that the yet-to-be-identified amino acid germinant receptor is highly promiscuous.
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Affiliation(s)
- Ritu Shrestha
- Department of Biology, Texas A&M University, College Station, TX 77843, United States
| | - Joseph A Sorg
- Department of Biology, Texas A&M University, College Station, TX 77843, United States.
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Gao JX, Li P, Du XJ, Han ZH, Xue R, Liang B, Wang S. A Negative Regulator of Cellulose Biosynthesis, bcsR, Affects Biofilm Formation, and Adhesion/Invasion Ability of Cronobacter sakazakii. Front Microbiol 2017; 8:1839. [PMID: 29085341 PMCID: PMC5649176 DOI: 10.3389/fmicb.2017.01839] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2017] [Accepted: 09/08/2017] [Indexed: 12/17/2022] Open
Abstract
Cronobacter sakazakii is an important foodborne pathogen that causes neonatal meningitis and sepsis, with high mortality in neonates. However, very little information is available regarding the pathogenesis of C. sakazakii at the genetic level. In our previous study, a cellulose biosynthesis-related gene (bcsR) was shown to be involved in C. sakazakii adhesion/invasion into epithelial cells. In this study, the detailed functions of this gene were investigated using a gene knockout technique. A bcsR knockout mutant (ΔbcsR) of C. sakazakii ATCC BAA-894 showed decreased adhesion/invasion (3.9-fold) in human epithelial cell line HCT-8. Biofilm formation by the mutant was reduced to 50% of that exhibited by the wild-type (WT) strain. Raman spectrometry was used to detect variations in biofilm components caused by bcsR knockout, and certain components, including carotenoids, fatty acids, and amides, were significantly reduced. However, another biofilm component, cellulose, was increased in ΔbcsR, suggesting that bcsR negatively affects cellulose biosynthesis. This result was also verified via RT-PCR, which demonstrated up-regulation of five crucial cellulose synthesis genes (bcsA, B, C, E, Q) in ΔbcsR. Furthermore, the expression of other virulence or biofilm-related genes, including flagellar assembly genes (fliA, C, D) and toxicity-related genes (ompA, ompX, hfq), was studied. The expression of fliC and ompA in the ΔbcsR mutant was found to be remarkably reduced compared with that in the wild-type and the others were also affected excepted ompX. In summary, bcsR is a negative regulator of cellulose biosynthesis but positively regulates biofilm formation and the adhesion/invasion ability of C. sakazakii.
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Affiliation(s)
- Jian-Xin Gao
- Key Laboratory of Food Nutrition and Safety, Ministry of Education, Tianjin University of Science and Technology, Tianjin, China
| | - Ping Li
- Key Laboratory of Food Nutrition and Safety, Ministry of Education, Tianjin University of Science and Technology, Tianjin, China
| | - Xin-Jun Du
- Key Laboratory of Food Nutrition and Safety, Ministry of Education, Tianjin University of Science and Technology, Tianjin, China
| | - Zhong-Hui Han
- Key Laboratory of Food Nutrition and Safety, Ministry of Education, Tianjin University of Science and Technology, Tianjin, China
| | - Rui Xue
- Key Laboratory of Food Nutrition and Safety, Ministry of Education, Tianjin University of Science and Technology, Tianjin, China
| | - Bin Liang
- Key Laboratory of Food Nutrition and Safety, Ministry of Education, Tianjin University of Science and Technology, Tianjin, China
| | - Shuo Wang
- Key Laboratory of Food Nutrition and Safety, Ministry of Education, Tianjin University of Science and Technology, Tianjin, China.,Beijing Advanced Innovation Center for Food Nutrition and Human Health, Beijing Technology and Business University, Beijing, China
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Shrestha R, Lockless SW, Sorg JA. A Clostridium difficile alanine racemase affects spore germination and accommodates serine as a substrate. J Biol Chem 2017; 292:10735-10742. [PMID: 28487371 DOI: 10.1074/jbc.m117.791749] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2017] [Revised: 05/07/2017] [Indexed: 12/18/2022] Open
Abstract
Clostridium difficile has become one of the most common bacterial pathogens in hospital-acquired infections in the United States. Although C. difficile is strictly anaerobic, it survives in aerobic environments and transmits between hosts via spores. C. difficile spore germination is triggered in response to certain bile acids and glycine. Although glycine is the most effective co-germinant, other amino acids can substitute with varying efficiencies. Of these, l-alanine is an effective co-germinant and is also a germinant for most bacterial spores. Many endospore-forming bacteria embed alanine racemases into their spore coats, and these enzymes are thought to convert the l-alanine germinant into d-alanine, a spore germination inhibitor. Although the C. difficile Alr2 racemase is the sixth most highly expressed gene during C. difficile spore formation, a previous study reported that Alr2 has little to no role in germination of C. difficile spores in rich medium. Here, we hypothesized that Alr2 could affect C. difficile l-alanine-induced spore germination in a defined medium. We found that alr2 mutant spores more readily germinate in response to l-alanine as a co-germinant. Surprisingly, d-alanine also functioned as a co-germinant. Moreover, we found that Alr2 could interconvert l- and d-serine and that Alr2 bound to l- and d-serine with ∼2-fold weaker affinity to that of l- and d-alanine. Finally, we demonstrate that l- and d-serine are also co-germinants for C. difficile spores. These results suggest that C. difficile spores can respond to a diverse set of amino acid co-germinants and reveal that Alr2 can accommodate serine as a substrate.
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Affiliation(s)
- Ritu Shrestha
- From the Department of Biology, Texas A&M University, College Station, Texas 77843
| | - Steve W Lockless
- From the Department of Biology, Texas A&M University, College Station, Texas 77843
| | - Joseph A Sorg
- From the Department of Biology, Texas A&M University, College Station, Texas 77843
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