Secretion of Clostridium difficile Toxins A and B Requires the Holin-like Protein TcdE

Autor: Revathi Govind, Bruno Dupuy
Přispěvatelé: Pathogénèse des Bactéries Anaérobies / Pathogenesis of Bacterial Anaerobes (PBA (U-Pasteur_6)), Institut Pasteur [Paris]-Université Paris Diderot - Paris 7 (UPD7), Division of Biology [Kansas State University], Kansas State University, This study was supported by funds provided to BD by the Institut Pasteur and a grant (R01 AI057637, A.L. Sonenshein, PI) from the US National Institute of Allergy and Infectious Diseases and by funds provided to RG by Kansas State University and a grant (P20 RR016475) from the INBRE Program of the US National Center for Research Resources., Institut Pasteur [Paris] (IP)-Université Paris Diderot - Paris 7 (UPD7)
Jazyk: angličtina
Rok vydání: 2012
Předmět:
MESH: Enterotoxins/metabolism
MESH: Clostridium difficile/metabolism
[SDV]Life Sciences [q-bio]
Lysin
MESH: Flow Cytometry
Enterotoxin
MESH: Amino Acid Sequence
MESH: Base Sequence
medicine.disease_cause
MESH: Bacterial Proteins/metabolism
Bacteriophage
Enterotoxins
MESH: Chlorocebus aethiops
Chlorocebus aethiops
MESH: Animals
lcsh:QH301-705.5
0303 health sciences
Clostridium difficile
Flow Cytometry
3. Good health
Holin
Gene Knockdown Techniques
MESH: Bacterial Proteins/genetics
Research Article
lcsh:Immunologic diseases. Allergy
MESH: Clostridium difficile/genetics
Immunology
Bacterial Toxins
Blotting
Western
Molecular Sequence Data
MESH: Vero Cells
Biology
MESH: Clostridium Infections/genetics
Microbiology
MESH: Clostridium Infections/metabolism
MESH: Gene Expression Regulation
Bacterial/physiology
03 medical and health sciences
Bacterial Proteins
Virology
Genetics
medicine
Animals
MESH: Blotting
Western
Secretion
[SDV.BBM]Life Sciences [q-bio]/Biochemistry
Molecular Biology
Amino Acid Sequence
Molecular Biology
Escherichia coli
Vero Cells
030304 developmental biology
MESH: Molecular Sequence Data
Base Sequence
030306 microbiology
Clostridioides difficile
Gene Expression Regulation
Bacterial
biology.organism_classification
MESH: Gene Knockdown Techniques
lcsh:Biology (General)
Membrane protein
MESH: Bacterial Toxins
Clostridium Infections
Parasitology
lcsh:RC581-607
Zdroj: PLoS Pathogens
PLoS Pathogens, Public Library of Science, 2012, 8 (6), pp.e1002727. ⟨10.1371/journal.ppat.1002727⟩
PLoS Pathogens, 2012, 8 (6), pp.e1002727. ⟨10.1371/journal.ppat.1002727⟩
PLoS Pathogens, Vol 8, Iss 6, p e1002727 (2012)
ISSN: 1553-7366
1553-7374
DOI: 10.1371/journal.ppat.1002727⟩
Popis: The pathogenesis of Clostridium difficile, the major cause of antibiotic-associated diarrhea, is mainly associated with the production and activities of two major toxins. In many bacteria, toxins are released into the extracellular environment via the general secretion pathways. C. difficile toxins A and B have no export signature and their secretion is not explainable by cell lysis, suggesting that they might be secreted by an unusual mechanism. The TcdE protein encoded within the C. difficile pathogenicity locus (PaLoc) has predicted structural features similar to those of bacteriophage holin proteins. During many types of phage infection, host lysis is driven by an endolysin that crosses the cytoplasmic membrane through a pore formed by holin oligomerization. We demonstrated that TcdE has a holin-like activity by functionally complementing a λ phage deprived of its holin. Similar to λ holin, TcdE expressed in Escherichia coli and C. difficile formed oligomers in the cytoplamic membrane. A C. difficile tcdE mutant strain grew at the same rate as the wild-type strain, but accumulated a dramatically reduced amount of toxin proteins in the medium. However, the complemented tcdE mutant released the toxins efficiently. There was no difference in the abundance of tcdA and tcdB transcripts or of several cytoplasmic proteins in the mutant and the wild-type strains. In addition, TcdE did not overtly affect membrane integrity of C. difficile in the presence of TcdA/TcdB. Thus, TcdE acts as a holin-like protein to facilitate the release of C. difficile toxins to the extracellular environment, but, unlike the phage holins, does not cause the non-specific release of cytosolic contents. TcdE appears to be the first example of a bacterial protein that releases toxins into the environment by a phage-like system.
Author Summary Clostridium difficile is the causative agent of antibiotic associated diarrhea and has become the most prevalent cause of infectious nosocomial diarrhea in North America and in several countries in Europe. Most virulent strains of C. difficile produce two high molecular weight toxins that are regarded as the primary virulence factors. The mechanism by which these large toxins are secreted from bacterial cells is not known. Unlike most clostridial toxins, they have no export signature and must be secreted by an unusual system. This work investigated the role of a C. difficile membrane protein TcdE in the release of toxins from the bacterial cell. We showed that C. difficile tcdE mutants were defective in toxin release and present evidence that C. difficile TcdE protein activity is similar to that of bacteriophage holin proteins required for lysis of host cells after intracellular phage development. These results suggest that TcdE helps efficient secretion of toxins by a phage type system. However, unlike phages, TcdE does not induce cell lysis. A detailed, mechanistic understanding of the holin-dependent system that mediates toxin secretion may helpful for the development of strategies for preventing and treating C. difficile infections.
Databáze: OpenAIRE
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