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Shrestha A, Mehdizadeh Gohari I, Li J, Navarro M, Uzal FA, McClane BA. The biology and pathogenicity of Clostridium perfringens type F: a common human enteropathogen with a new(ish) name. Microbiol Mol Biol Rev 2024; 88:e0014023. [PMID: 38864615 PMCID: PMC11426027 DOI: 10.1128/mmbr.00140-23] [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: 06/13/2024] Open
Abstract
SUMMARYIn the 2018-revised Clostridium perfringens typing classification system, isolates carrying the enterotoxin (cpe) and alpha toxin genes but no other typing toxin genes are now designated as type F. Type F isolates cause food poisoning and nonfoodborne human gastrointestinal (GI) diseases, which most commonly involve type F isolates carrying, respectivefooly, a chromosomal or plasmid-borne cpe gene. Compared to spores of other C. perfringens isolates, spores of type F chromosomal cpe isolates often exhibit greater resistance to food environment stresses, likely facilitating their survival in improperly prepared or stored foods. Multiple factors contribute to this spore resistance phenotype, including the production of a variant small acid-soluble protein-4. The pathogenicity of type F isolates involves sporulation-dependent C. perfringens enterotoxin (CPE) production. C. perfringens sporulation is initiated by orphan histidine kinases and sporulation-associated sigma factors that drive cpe transcription. CPE-induced cytotoxicity starts when CPE binds to claudin receptors to form a small complex (which also includes nonreceptor claudins). Approximately six small complexes oligomerize on the host cell plasma membrane surface to form a prepore. CPE molecules in that prepore apparently extend β-hairpin loops to form a β-barrel pore, allowing a Ca2+ influx that activates calpain. With low-dose CPE treatment, caspase-3-dependent apoptosis develops, while high-CPE dose treatment induces necroptosis. Those effects cause histologic damage along with fluid and electrolyte losses from the colon and small intestine. Sialidases likely contribute to type F disease by enhancing CPE action and, for NanI-producing nonfoodborne human GI disease isolates, increasing intestinal growth and colonization.
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Affiliation(s)
- Archana Shrestha
- Department of Microbiology and Molecular Genetics, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, USA
| | - Iman Mehdizadeh Gohari
- Department of Microbiology and Molecular Genetics, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, USA
| | - Jihong Li
- Department of Microbiology and Molecular Genetics, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, USA
| | - Mauricio Navarro
- Instituto de Patologia Animal, Facultad de Ciencias Veterinarias, Universidad Austral de Chile, Valdivia, Chile
| | - Francisco A Uzal
- California Animal Health and Food Safety Laboratory System, School of Veterinary Medicine, University of California Davis, San Bernardino, California, USA
| | - Bruce A McClane
- Department of Microbiology and Molecular Genetics, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, USA
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Zhu Y, Mou X, Song Y, Zhang Q, Sun B, Liu H, Tang H, Bao R. Molecular mechanism of the one-component regulator RccR on bacterial metabolism and virulence. Nucleic Acids Res 2024; 52:3433-3449. [PMID: 38477394 PMCID: PMC11014249 DOI: 10.1093/nar/gkae171] [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: 08/31/2023] [Revised: 02/22/2024] [Accepted: 02/27/2024] [Indexed: 03/14/2024] Open
Abstract
The regulation of carbon metabolism and virulence is critical for the rapid adaptation of pathogenic bacteria to host conditions. In Pseudomonas aeruginosa, RccR is a transcriptional regulator of genes involved in primary carbon metabolism and is associated with bacterial resistance and virulence, although the exact mechanism is unclear. Our study demonstrates that PaRccR is a direct repressor of the transcriptional regulator genes mvaU and algU. Biochemical and structural analyses reveal that PaRccR can switch its DNA recognition mode through conformational changes triggered by KDPG binding or release. Mutagenesis and functional analysis underscore the significance of allosteric communication between the SIS domain and the DBD domain. Our findings suggest that, despite its overall structural similarity to other bacterial RpiR-type regulators, RccR displays a more complex regulatory element binding mode induced by ligands and a unique regulatory mechanism.
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Affiliation(s)
- Yibo Zhu
- Center of Infectious Diseases, Division of Infectious Diseases in State Key Laboratory of Biotherapy, West China Hospital, Sichuan University, Chengdu, Sichuan 610041, China
| | - Xingyu Mou
- Center of Infectious Diseases, Division of Infectious Diseases in State Key Laboratory of Biotherapy, West China Hospital, Sichuan University, Chengdu, Sichuan 610041, China
| | - Yingjie Song
- College of Life Science, Sichuan Normal University, Chengdu, China
| | - Qianqian Zhang
- Centre for Artificial Intelligence Driven Drug Discovery, Faculty of Applied Sciences, Macao Polytechnic University, Macao 999078, China
| | - Bo Sun
- Shanghai Advanced Research Institute, Chinese Academy of Sciences, Shanghai, China
| | - Huanxiang Liu
- Centre for Artificial Intelligence Driven Drug Discovery, Faculty of Applied Sciences, Macao Polytechnic University, Macao 999078, China
| | - Hong Tang
- Center of Infectious Diseases, Division of Infectious Diseases in State Key Laboratory of Biotherapy, West China Hospital, Sichuan University, Chengdu, Sichuan 610041, China
| | - Rui Bao
- Center of Infectious Diseases, Division of Infectious Diseases in State Key Laboratory of Biotherapy, West China Hospital, Sichuan University, Chengdu, Sichuan 610041, China
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Abrashev R, Krumova E, Petrova P, Eneva R, Dishliyska V, Gocheva Y, Engibarov S, Miteva-Staleva J, Spasova B, Kolyovska V, Angelova M. Glucose Catabolite Repression Participates in the Regulation of Sialidase Biosynthesis by Antarctic Strain Penicillium griseofulvum P29. J Fungi (Basel) 2024; 10:241. [PMID: 38667912 PMCID: PMC11051313 DOI: 10.3390/jof10040241] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2024] [Revised: 03/18/2024] [Accepted: 03/21/2024] [Indexed: 04/28/2024] Open
Abstract
Sialidases (neuraminidases) catalyze the removal of terminal sialic acid residues from glycoproteins. Novel enzymes from non-clinical isolates are of increasing interest regarding their application in the food and pharmaceutical industry. The present study aimed to evaluate the participation of carbon catabolite repression (CCR) in the regulation of cold-active sialidase biosynthesis by the psychrotolerant fungal strain Penicillium griseofulvum P29, isolated from Antarctica. The presence of glucose inhibited sialidase activity in growing and non-growing fungal mycelia in a dose- and time-dependent manner. The same response was demonstrated with maltose and sucrose. The replacement of glucose with glucose-6-phosphate also exerted CCR. The addition of cAMP resulted in the partial de-repression of sialidase synthesis. The CCR in the psychrotolerant strain P. griseofulvum P29 did not depend on temperature. Sialidase might be subject to glucose repression by both at 10 and 25 °C. The fluorescent assay using 4MU-Neu5Ac for enzyme activity determination under increasing glucose concentrations evidenced that CCR may have a regulatory role in sialidase production. The real-time RT-PCR experiments revealed that the sialidase gene was subject to glucose repression. To our knowledge, this is the first report that has studied the effect of CCR on cold-active sialidase, produced by an Antarctic strain.
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Affiliation(s)
- Radoslav Abrashev
- Department of Mycology, The Stephan Angeloff Institute of Microbiology, Bulgarian Academy of Sciences, Academician G. Bonchev 26, 1113 Sofia, Bulgaria; (R.A.); (E.K.); (V.D.); (J.M.-S.); (B.S.)
| | - Ekaterina Krumova
- Department of Mycology, The Stephan Angeloff Institute of Microbiology, Bulgarian Academy of Sciences, Academician G. Bonchev 26, 1113 Sofia, Bulgaria; (R.A.); (E.K.); (V.D.); (J.M.-S.); (B.S.)
| | - Penka Petrova
- Department of General Microbiology, The Stephan Angeloff Institute of Microbiology, Bulgarian Academy of Sciences, Academician G. Bonchev 26, 1113 Sofia, Bulgaria; (P.P.); (R.E.); (Y.G.); (S.E.)
| | - Rumyana Eneva
- Department of General Microbiology, The Stephan Angeloff Institute of Microbiology, Bulgarian Academy of Sciences, Academician G. Bonchev 26, 1113 Sofia, Bulgaria; (P.P.); (R.E.); (Y.G.); (S.E.)
| | - Vladislava Dishliyska
- Department of Mycology, The Stephan Angeloff Institute of Microbiology, Bulgarian Academy of Sciences, Academician G. Bonchev 26, 1113 Sofia, Bulgaria; (R.A.); (E.K.); (V.D.); (J.M.-S.); (B.S.)
| | - Yana Gocheva
- Department of General Microbiology, The Stephan Angeloff Institute of Microbiology, Bulgarian Academy of Sciences, Academician G. Bonchev 26, 1113 Sofia, Bulgaria; (P.P.); (R.E.); (Y.G.); (S.E.)
| | - Stefan Engibarov
- Department of General Microbiology, The Stephan Angeloff Institute of Microbiology, Bulgarian Academy of Sciences, Academician G. Bonchev 26, 1113 Sofia, Bulgaria; (P.P.); (R.E.); (Y.G.); (S.E.)
| | - Jeny Miteva-Staleva
- Department of Mycology, The Stephan Angeloff Institute of Microbiology, Bulgarian Academy of Sciences, Academician G. Bonchev 26, 1113 Sofia, Bulgaria; (R.A.); (E.K.); (V.D.); (J.M.-S.); (B.S.)
| | - Boryana Spasova
- Department of Mycology, The Stephan Angeloff Institute of Microbiology, Bulgarian Academy of Sciences, Academician G. Bonchev 26, 1113 Sofia, Bulgaria; (R.A.); (E.K.); (V.D.); (J.M.-S.); (B.S.)
| | - Vera Kolyovska
- Institute of Experimental Morphology, Pathology and Anthropology with Museum, Bulgarian Academy of Sciences, Academician G. Bonchev 25, 1113 Sofia, Bulgaria;
| | - Maria Angelova
- Department of Mycology, The Stephan Angeloff Institute of Microbiology, Bulgarian Academy of Sciences, Academician G. Bonchev 26, 1113 Sofia, Bulgaria; (R.A.); (E.K.); (V.D.); (J.M.-S.); (B.S.)
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Li J, Pradhan A, McClane BA. NanJ Is the Major Sialidase for Clostridium perfringens Type F Food Poisoning Strain 01E809. Infect Immun 2023; 91:e0005323. [PMID: 37212696 PMCID: PMC10269042 DOI: 10.1128/iai.00053-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2023] [Accepted: 05/01/2023] [Indexed: 05/23/2023] Open
Abstract
Clostridium perfringens type F strains cause food poisoning (FP) when they sporulate and produce C. perfringens enterotoxin (CPE) in the intestines. Most type F FP strains carry a chromosomal cpe gene (c-cpe strains). C. perfringens produces up to three different sialidases, named NanH, NanI, and NanJ, but some c-cpe FP strains carry only nanJ and nanH genes. This study surveyed a collection of such strains and showed that they produce sialidase activity when cultured in Todd-Hewitt broth (TH) (vegetative cultures) or modified Duncan-Strong (MDS) medium (sporulating cultures). Sialidase null mutants were constructed in 01E809, a type F c-cpe FP strain carrying the nanJ and nanH genes. Characterization of those mutants identified NanJ as the major sialidase of 01E809 and showed that, in vegetative and sporulating cultures, nanH expression affects nanJ expression and vice versa; those regulatory effects may involve media-dependent changes in transcription of the codY or ccpA genes but not nanR. Additional characterization of these mutants demonstrated the following: (i) NanJ contributions to growth and vegetative cell survival are media dependent, with this sialidase increasing 01E809 growth in MDS but not TH; (ii) NanJ enhances 24-h vegetative cell viability in both TH and MDS cultures; and (iii) NanJ is important for 01E809 sporulation and, together with NanH, CPE production in MDS cultures. Lastly, NanJ was shown to increase CPE-induced cytotoxicity and CH-1 pore formation in Caco-2 cells. Collectively, these results suggest that NanJ may have a contributory role in FP caused by type F c-cpe strains that carry the nanH and nanJ genes.
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Affiliation(s)
- Jihong Li
- Department of Microbiology and Molecular Genetics, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, USA
| | - Arhat Pradhan
- Department of Microbiology and Molecular Genetics, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, USA
| | - Bruce A. McClane
- Department of Microbiology and Molecular Genetics, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, USA
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Characterization of NanR Regulation of Sialidase Production, Sporulation and Enterotoxin Production by Clostridium perfringens Type F Strains Carrying a Chromosomal Enterotoxin Gene. Toxins (Basel) 2022; 14:toxins14120872. [PMID: 36548769 PMCID: PMC9788507 DOI: 10.3390/toxins14120872] [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: 11/14/2022] [Revised: 12/08/2022] [Accepted: 12/10/2022] [Indexed: 12/15/2022] Open
Abstract
Clostridium perfringens type F food poisoning (FP) strains produce C. perfringens enterotoxin (CPE) to cause a common bacterial food-borne illness in the United States. During FP, CPE is synthesized in the intestines when C. perfringens sporulates. Besides CPE, FP strains also produce sialidases. Most FP strains carry their cpe gene on the chromosome and all surveyed chromosomal cpe (c-cpe) FP strains produce NanH sialidase or both NanJ and NanH sialidases. NanR has been shown previously to regulate sialidase activity in non-FP strains. The current study investigated whether NanR also regulates sialidase activity or influences sporulation and CPE production for c-cpe FP strains SM101 and 01E809. In sporulation medium, the SM101 nanR null mutant showed lower sialidase activity, sporulation, and CPE production than its wild-type parent, while the 01E809 nanR null mutant showed roughly similar sialidase activity, sporulation, and CPE production as its parent. In vegetative medium, the nanR null mutants of both strains produced more spores than their parents while NanR repressed sialidase activity in SM101 but positively regulated sialidase activity in 01E809. These results demonstrate that NanR regulates important virulence functions of c-cpe strains, with this control varying depending on strain and culture conditions.
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NanI sialidase contributes to toxin expression and host cell binding of Clostridium perfringens type G strain CP56 in vitro. Vet Microbiol 2022; 266:109371. [DOI: 10.1016/j.vetmic.2022.109371] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2021] [Revised: 02/08/2022] [Accepted: 02/10/2022] [Indexed: 11/20/2022]
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Li J, Navarro MA, Uzal FA, McClane BA. NanI Sialidase Contributes to the Growth and Adherence of Clostridium perfringens Type F Strain F4969 in the Presence of Adherent Mucus. Infect Immun 2021; 89:e0025621. [PMID: 34424746 PMCID: PMC8519267 DOI: 10.1128/iai.00256-21] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2021] [Accepted: 07/30/2021] [Indexed: 12/13/2022] Open
Abstract
Clostridium perfringens type F strains causing nonfoodborne human gastrointestinal diseases (NFD) typically produce NanI sialidase as their major secreted sialidase. Type F NFDs can persist for several weeks, indicating their pathogenesis involves intestinal colonization, including vegetative cell growth and adherence, with subsequent sporulation that fosters enterotoxin production and release. We previously reported that NanI contributes to type F NFD strain adherence and growth using Caco-2 cells. However, Caco-2 cells make minimal amounts of mucus, which is significant because the intestines are coated with adherent mucus. Therefore, it was important to assess if NanI contributes to the growth and adherence of type F NFD strains in the presence of adherent mucus. Consequently, the current study first demonstrated greater growth of nanI-carrying versus non-nanI-carrying type F strains in the presence of HT29-MTX-E12 cells, which produce an adherent mucus layer, versus their parental HT29 cells, which make minimal mucus. Demonstrating the specific importance of NanI for this effect, type F NFD strain F4969 or a complementing strain grew and adhered better than an isogenic nanI null mutant in the presence of HT29-MTX-E12 cells versus HT29 cells. Those effects involved mucus production by HT29-MTX-E12 cells since mucus reduction using N-acetyl cysteine reduced F4969 growth and adherence. Consistent with those in vitro results, NanI contributed to growth of F4969 in the mouse small intestine. By demonstrating a growth and adherence role for NanI in the presence of adherent mucus, these results further support NanI as a potential virulence factor during type F NFDs.
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Affiliation(s)
- Jihong Li
- Department of Microbiology and Molecular Genetics, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, USA
| | - Mauricio A. Navarro
- California Animal Health and Food Safety Laboratory, School of Veterinary Medicine, University of California Davis, San Bernardino, California, USA
| | - Francisco A. Uzal
- California Animal Health and Food Safety Laboratory, School of Veterinary Medicine, University of California Davis, San Bernardino, California, USA
| | - Bruce A. McClane
- Department of Microbiology and Molecular Genetics, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, USA
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Identifying the Basis for VirS/VirR Two-Component Regulatory System Control of Clostridium perfringens Beta-Toxin Production. J Bacteriol 2021; 203:e0027921. [PMID: 34228498 DOI: 10.1128/jb.00279-21] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Clostridium perfringens toxin production is often regulated by the Agr-like quorum sensing (QS) system signaling the VirS/VirR two-component regulatory system (TCRS), which consists of the VirS membrane sensor histidine kinase and the VirR response regulator. VirS/VirR is known to directly control expression of some genes by binding to a DNA binding motif consisting of two VirR boxes located within 500 bp of the target gene start codon. Alternatively, the VirS/VirR system can indirectly regulate production levels of other proteins by increasing expression of a small regulatory RNA, VR-RNA. Previous studies demonstrated that C. perfringens beta-toxin (CPB) production by C. perfringens type B and C strains is positively regulated by both the Agr-like QS and the VirS/VirR TCRS, but the mechanism has been unclear. The current study first inactivated the vrr gene encoding VR-RNA to show that VirS/VirR regulation of cpb expression does not involve VR-RNA. Subsequently, bioinformatic analyses identified a potential VirR binding motif, along with a predicted strong promoter, ∼1.4 kb upstream of the cpb open reading frame (ORF). Two insertion sequences were present between this VirR binding motif/promoter region and the cpb ORF. PCR screening of a collection of strains carrying cpb showed that the presence and sequence of this VirR binding motif/promoter is highly conserved among CPB-producing strains. Reverse transcription-PCR (RT-PCR) and a GusA reporter assay showed this VirR binding motif is important for regulating CPB production. These findings indicate that VirS/VirR directly regulates cpb expression via VirS binding to a VirR binding motif located unusually distant from the cpb start codon. IMPORTANCE Clostridium perfringens beta-toxin (CPB) is only produced by type B and C strains. Production of CPB is essential for the pathogenesis of type C-associated infections, which include hemorrhagic necrotizing enteritis and enterotoxemia in both humans and animals. In addition, CPB can synergize with other toxins during C. perfringens gastrointestinal diseases. CPB toxin production is cooperatively regulated by the Agr-like quorum sensing (QS) system and the VirS/VirR two-component regulatory system. This study now reports that the VirS/VirR regulatory cascade directly controls expression of the cpb gene via a process involving a VirR box binding motif located unusually far (∼1.4 kb) upstream of the cpb ORF. This study provides a better understanding of the regulatory mechanisms for CPB production by the VirS/VirR regulatory cascade.
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Wang YH. Sialidases From Clostridium perfringens and Their Inhibitors. Front Cell Infect Microbiol 2020; 9:462. [PMID: 31998664 PMCID: PMC6966327 DOI: 10.3389/fcimb.2019.00462] [Citation(s) in RCA: 29] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2019] [Accepted: 12/16/2019] [Indexed: 12/27/2022] Open
Abstract
Clostridium perfringens is an important human and animal pathogen that is the primary causative agent of necrotizing enteritis and enterotoxemia in many types of animals; it causes traumatic gas gangrene in humans and animals and is associated with cases of food poisoning in humans. C. perfringens produces a variety of toxins as well as many enzymes, including three sialidases, NanH, NanI, and NanJ. Sialidases could be important virulence factors that promote the pathogenesis of C. perfringens. Among them, NanI promotes the colonization of C. perfringens in the intestinal tract and enhances the cytotoxic activity and association of several major C. perfringens toxins with host cells. In recent years, studies on the structure and functions of sialidases have yielded interesting results, and the functions of sialic acid and sialidases in bacterial pathogenesis have become a hot research topic. An in-depth understanding and additional studies of sialidases will further elucidate mechanisms of C. perfringens pathogenesis and could promote the development and clinical applications of sialidase inhibitors. This article reviews the structural characteristics, expression regulation, roles of sialidases in C. perfringens pathogenesis, and effects of their inhibitors.
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Affiliation(s)
- Yan-Hua Wang
- State Key Laboratory of Veterinary Etiological Biology, Lanzhou Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Lanzhou, China
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NanI Sialidase Is an Important Contributor to Clostridium perfringens Type F Strain F4969 Intestinal Colonization in Mice. Infect Immun 2018; 86:IAI.00462-18. [PMID: 30297524 DOI: 10.1128/iai.00462-18] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2018] [Accepted: 09/28/2018] [Indexed: 12/19/2022] Open
Abstract
Clostridium perfringens type F (formerly enterotoxigenic C. perfringens type A) strains produce an enterotoxin (CPE) to cause acute cases of food poisoning and chronic nonfoodborne human gastrointestinal diseases (NFD), e.g., antibiotic-associated diarrhea (AAD). NFD strains also produce NanI sialidase, an extracellular enzyme that releases sialic acids from sialyated host macromolecules. Recent in vitro studies suggested that NanI may contribute to NFD strain intestinal colonization by enhancing the adherence of such strains to intestinal cells and promoting their bacterial growth using generated sialic acid as an energy source. The current study tested this hypothesis by developing a mouse intestinal colonization model involving clindamycin pretreatment to produce conditions mimicking those during AAD. In this model, the type F NFD strain F4969 persisted for at least 4 days in the small intestine, cecum, and colon. When clindamycin-pretreated mice were challenged by oral gavage with equivalent numbers of F4969 bacteria or its isogenic nanI null mutant, significantly lower numbers of the nanI mutant were recovered from all intestinal segments, and it was completely cleared from the small intestine by day 4. Complementation of the mutant to restore NanI production also promoted colonization. When the same nanI null mutant strain was coinoculated into the mouse model together with a nanI-producing strain, the numbers of this mutant were restored to wild-type F4969 levels in all intestinal segments. This result suggests that sialidases produced by other bacteria might also provide some support for C. perfringens intestinal colonization. Collectively, these in vivo findings identify NanI to be the first known significant contributor to chronic intestinal colonization by NFD strains.
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NanR Regulates Sporulation and Enterotoxin Production by Clostridium perfringens Type F Strain F4969. Infect Immun 2018; 86:IAI.00416-18. [PMID: 30082481 DOI: 10.1128/iai.00416-18] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2018] [Accepted: 08/01/2018] [Indexed: 12/20/2022] Open
Abstract
Clostridium perfringens type F strains, which produce C. perfringens enterotoxin (CPE), are a major cause of gastrointestinal infections, including the second most prevalent bacterial foodborne illness and 5 to 10% cases of antibiotic-associated diarrhea. Virulence of type F strains is primarily ascribable to CPE, which is synthesized only during sporulation. Many type F strains also produce NanI sialidase and carry a nan operon that likely facilitates uptake and metabolism of sialic acid liberated from glycoconjugates by NanI. During vegetative growth of type F strain F4969, NanR can regulate expression of nanI Given their importance for type F disease, the current study investigated whether NanR can also influence sporulation and CPE production when F4969 or isogenic derivatives are cultured in modified Duncan-Strong sporulation (MDS) medium. An isogenic F4969 nanR null mutant displayed much less sporulation and CPE production but more NanI production than wild-type F4969, indicating that NanR positively regulates sporulation and CPE production but represses NanI production in MDS. Results for the nanR mutant also demonstrated that NanR regulates expression of the nan operon. A nanI nanR double null mutant mirrored the outcome of the nanR null mutant strain but with a stronger inhibition of sporulation and CPE production, even after overnight incubation. Coupled with results using a nanI null mutant, which had no impairment of sporulation or CPE production, NanR appears to carefully modulate the availability of NanI, nan operon-encoded proteins and sialic acid to provide sufficient nutrients to sustain sporulation and CPE production when F4969 is cultured in MDS medium.
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NanI Sialidase Can Support the Growth and Survival of Clostridium perfringens Strain F4969 in the Presence of Sialyated Host Macromolecules (Mucin) or Caco-2 Cells. Infect Immun 2018; 86:IAI.00547-17. [PMID: 29203541 DOI: 10.1128/iai.00547-17] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2017] [Accepted: 11/22/2017] [Indexed: 12/27/2022] Open
Abstract
Enterotoxin-producing Clostridium perfringens type A strains cause human gastrointestinal (GI) infections, including a very common food poisoning and 5 to 10% of all cases of antibiotic-associated diarrhea. This bacterium can utilize free sialic acid for growth, but most sialic acids in the GI tract are sequestered on macromolecules, such as the mucin proteins of mucus or glycoconjugates in host cells. However, many C. perfringens strains produce sialidases that might promote growth and survival by generating free sialic acid from those sialyated host macromolecules or by exposing underlying carbohydrates or proteins for digestion by other enzymes. The current study tested that possibility and found that the C. perfringens nonfoodborne human GI disease strain F4969 can use either a mucin preparation or Caco-2 cells, which are human enterocyte-like cells, to support its growth and survival. An isogenic nanI null mutant and complemented strain were used to show that this enhanced growth and survival using mucin or Caco-2 cells involved NanI, which is the major exosialidase of F4969 and many other C. perfringens strains. Experiments also suggested that, at least in part, this growth promotion involves utilization of NanI-generated sialic acid. In addition, a sialidase inhibitor named siastatin B reduced the growth and survival of F4969 growing with either the mucin preparation or Caco-2 cells. These findings suggest that, when produced, NanI may be a significant contributor to C. perfringens human GI infections by promoting the intestinal growth and survival of this bacterium. They also suggest the possibility that sialidase inhibitors might inhibit C. perfringens infections.
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