title: Expression of Clostridium difficile toxins A and B and their sigma factor TcdD is controlled by temperature.
abstract: Growth temperature was found to control the expression of toxins A and B in Clostridium difficile VPI 10463, with a maximum at 37 degrees C and low levels at 22 and 42 degrees C in both peptone yeast (PY) and defined media. The up-regulation of toxin A and B mRNA and protein levels upon temperature upshift from 22 to 37 degrees C followed the same kinetics, showing that temperature control occurred at the level of transcription. Experiments with Clostridium perfringens using gusA as a reporter gene demonstrated that both toxin gene promoters were temperature controlled and that their high activity at 37 degrees C was dependent on the alternative sigma factor TcdD. Furthermore, tcdD was found to be autoinduced at 37 degrees C. Glucose down-regulated all these responses in the C. perfringens constructs, similar to its impact on toxin production in C. difficile PY broth cultures. C. difficile proteins induced at 37 degrees C and thus coregulated with the toxins by temperature were demonstrated by two-dimensional sodium dodecyl sulfate-polyacrylamide gel electrophoresis and identified as enzymes involved in butyric acid production and as electron carriers in oxidation-reduction reactions. The regulation of toxin production in C. difficile by temperature is a novel finding apparently reflecting an adaptation of the expression of its virulence to mammalian hosts.
authors.affiliation: Department of Molecular Epidemiology and Biotechnology, Swedish Institute for Infectious Disease Control, S-171 82 Solna, Sweden.
authors.forename: Sture
authors.initials: S
authors.lastname: Karlsson
authors.forename: Bruno
authors.initials: B
authors.lastname: Dupuy
authors.forename: Kakoli
authors.initials: K
authors.lastname: Mukherjee
authors.forename: Elisabeth
authors.initials: E
authors.lastname: Norin
authors.forename: Lars G
authors.initials: LG
authors.lastname: Burman
authors.forename: Thomas
authors.initials: T
authors.lastname: Akerlund
mesh_terms: D001426:Bacterial Proteins; D001427:Bacterial Toxins / Q000235:genetics / Q000378:metabolism*; D020148:Butyric Acid / Q000378:metabolism; D016360:Clostridioides difficile / Q000254:growth & development / Q000378:metabolism*; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D004768:Enterotoxins / Q000235:genetics / Q000378:metabolism*; D015964:Gene Expression Regulation, Bacterial; D006801:Humans; D011401:Promoter Regions, Genetic; D013696:Temperature; D014158:Transcription, Genetic
chemical_list: D001426:Bacterial Proteins; D001427:Bacterial Toxins; D004268:DNA-Binding Proteins; D004768:Enterotoxins; C105616:TcdD protein, Clostridium difficile; C041348:tcdA protein, Clostridium difficile; C031815:toxB protein, Clostridium difficile; D020148:Butyric Acid