Cloning of Clostridium difficile toxin B gene and demonstration of high N-terminal homology between toxin A and B

Med Microbiol Immunol. 1990;179(5):271-9. doi: 10.1007/BF00192465.


High titered Clostridium sordellii lethal toxin antiserum, cross-reactive with C. difficile cytotoxin B (ToxB), was used to isolate toxB fragments from a C. difficile expression library. Recombinant clones containing toxB fragments of the 5' and 3' end were isolate. A 2.5-kb HincII fragment of chromosomal DNA overlaps both groups of clones. A partial restriction map of the total toxB gene is presented. The gene is positioned upstream of utxA and toxA, toxB has a size of 6.9 kb, corresponding to a 250-kDa polypeptide. A partial sequence of the 5' end of toxB was determined. The sequence contains 398 bp upstream of toxB with a putative Shine-Dalgarno box (AGGAGA) and 609 bp of the toxB open reading frame. The N-terminal 203 amino acids of ToxB were compared with the N-terminal amino acids of the enterotoxin A (ToxA). A homology of 64% of the residues was detected, which proves the relatedness of ToxA and ToxB of C. difficile.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Sequence
  • Antibodies, Bacterial
  • Bacterial Proteins*
  • Bacterial Toxins / genetics*
  • Bacterial Toxins / immunology
  • Base Sequence
  • Cloning, Molecular
  • Clostridioides difficile / genetics*
  • Clostridioides difficile / immunology
  • Cross Reactions
  • DNA Probes
  • DNA, Bacterial / genetics
  • Genes, Bacterial*
  • Molecular Sequence Data
  • Restriction Mapping
  • Sequence Homology, Nucleic Acid


  • Antibodies, Bacterial
  • Bacterial Proteins
  • Bacterial Toxins
  • DNA Probes
  • DNA, Bacterial
  • toxB protein, Clostridium difficile