Open AccessA nonsense mutation abrogates production of a functional enterotoxin A in Clostridium difficile toxinotype VIII strains of serogroups F and X
Author(s) -
EichelStreiber Christoph,
ZecPirnat Ines,
Grabnar Miklavz,
Rupnik Maja
Publication year - 1999
Publication title -
fems microbiology letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.899
H-Index - 151
eISSN - 1574-6968
pISSN - 0378-1097
DOI - 10.1111/j.1574-6968.1999.tb13773.x
Subject(s) - recombinant dna , nonsense mutation , ligand (biochemistry) , toxin , clostridium difficile toxin a , microbiology and biotechnology , enterotoxin , biology , mutation , clostridium difficile , amino acid , strain (injury) , chemistry , gene , genetics , escherichia coli , receptor , anatomy , missense mutation , antibiotics
Clostridium difficile strains of toxinotype VIII from serogroups F and X are described as toxin B‐positive, toxin A‐negative (TcdB + A − ), although they harbour almost the entire tcdA gene. To identify the reason for the lack of TcdA detection, we analyzed catalytic and ligand domains of TcdA‐1470 of the type strain of serogroup F, strain 1470. Using recombinant fragments, the C‐terminal immunodominant ligand domain TcdA 3 ‐1470, spanning amino acid residues 1694–2711 (corresponding to VPI 10463 sequence), was detected in Western blots. Similar experiments using the recombinant N‐terminal catalytic fragment TcdA c1‐2 ‐1470 (amino acid positions 1–544) failed. In addition, this fragment showed no glucosylation activity. We determined the size and the position of alterations in the ligand domain tcdA 3 ‐1470 by DNA sequencing. Within the N‐terminal fragment tcdA c1‐2 ‐1470, a nonsense mutation was identified introducing a stop codon at amino acid position 47. Identical mutations were found in the two serogroup X strains 17663 and 10355. The mutation might explain the lack of TcdA production observed in strains of serotypes F and X.