title: ADP-ribosylating binary toxin genes of Clostridium difficile strain CCUG 20309.
abstract: The cdt genes that encode a binary ADP-ribosylating toxin in Clostridium difficile were first characterized from a toxigenic C. difficile strain CD196 in 1997. We report here C. difficile strain CCUG 20309 (ATCC 8864), a strain that produces toxin B but not toxin A, also carry a complete set of cdtA and cdtB genes. These genes were sequenced by cycle sequencing method. The 2 ORFs and the intergenic sequences of these 2 strains have a homology of 99.6%. Interestingly, 9 extra bases were found within the cdtA gene of strain CCUG 20309 which do not affect the downstream region of the ORF. Using the same homologous primers, the highly toxigenic reference strain VPI 10463 was found to carry only parts of the 2 ORFs while a nontoxigenic strain ATCC 8884 does not carry any of the cdt genes. Though it remains to be determined whether these genes are expressed, it is significant that strain CCUG 20309 contains the complete set of cdt genes. We speculate that the putative expressed proteins may contribute to pathogenesis, for example, enterotoxicity, of this unique strain of bacteria.
authors.affiliation: Department of Microbiology, Faculty of Medicine, National University of Singapore, 5 Science Drive 2, Singapore 117597, Republic of Singapore.
authors.forename: S Y
authors.initials: SY
authors.lastname: Chang
authors.forename: K P
authors.initials: KP
authors.lastname: Song
mesh_terms: D036002:ADP Ribose Transferases / Q000235:genetics*; D000595:Amino Acid Sequence; D019943:Amino Acid Substitution / Q000235:genetics; D001426:Bacterial Proteins; D001483:Base Sequence; D016360:Clostridioides difficile / Q000235:genetics*; D008969:Molecular Sequence Data
chemical_list: D001426:Bacterial Proteins; D036002:ADP Ribose Transferases; C410164:actin-specific ADP-ribosyltransferase, Clostridium