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Regulated transcription of Clostridium difficile toxin genes (1998)

Dupuy, Bruno ; Sonenshein, Abraham L.

Oxford BSL : Blackwell Publishing Ltd

Molecular microbiology 27 (1998), S. 0

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ISSN: 1365-2958

Source: Blackwell Publishing Journal Backfiles 1879-2005

Topics: Biology , Medicine

Notes: The Clostridium difficile toxA and toxB genes, encoding cytotoxic and enterotoxic proteins responsible for antibiotic-associated colitis and pseudomembranous colitis, were shown to be transcribed both from gene-specific promoters and from promoters of upstream genes. However, the gene-specific transcripts represented the majority of tox gene mRNAs. The 5′ ends of these mRNAs were shown to correspond to DNA sequences that had promoter activity when fused to the Escherichia coliβ-glucuronidase (gusA) gene and introduced into C. perfringens. The appearance of tox mRNA in C. difficile was repressed during exponential growth phase but increased substantially as cells entered stationary phase. When glucose or other rapidly metabolizable sugars were present in the medium, the stationary phase-associated induction was inhibited, indicating that the toxin genes are subject to a form of catabolite repression. This glucose effect was general to many toxinogenic strains having varying levels of toxin production.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1046/j.1365-2958.1998.00663.x

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Genome mapping of Clostridium perfringens strains with I-CeuI shows many virulence genes to be plasmid-borne (1996)

Katayama, Seiichi ; Dupuy, Bruno ; Daube, Georges ; [et al.]

Springer

Molecular genetics and genomics 251 (1996), S. 720-726

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ISSN: 1617-4623

Keywords: Key words Gangrene ; Toxins ; Enterotoxin ; Plasmids ; Genome mapping

Source: Springer Online Journal Archives 1860-2000

Topics: Biology

Notes: Abstract The intron-encoded endonuclease I-CeuI from Chlamydomonas eugametos was shown to cleave the circular chromosomes of all Clostridium perfringens strains examined at single sites in the rRNA operons, thereby generating ten fragments suitable for the rapid mapping of virulence genes by pulsed-field gel electrophoresis (PFGE). This method easily distinguishes between plasmid and chromosomal localisations, as I-CeuI only cuts chromosomal DNA. Using this approach, the genes for three of the four typing toxins, β, ɛ, and ι, in addition to the enterotoxin and λ-toxin genes, were shown to be plasmid-borne. In a minority of strains, associated with food poisoning, where the enterotoxin toxin gene was located on the chromosome, genes for two of the minor toxins, θ and μ, were missing.