THE ENTEROTOXIN-D PLASMID OF STAPHYLOCOCCUS-AUREUS ENCODES A 2ND ENTEROTOXIN DETERMINANT (SEJ)

Staphylococcus aureus enterotoxin D is one of the serotypes most commo nly associated with food poisoning. Further characterization of the en terotoxin D-encoding plasmid revealed the presence of an open reading frame which encodes a previously unidentified enterotoxin, designated staphylococcal enterotoxin J (SEJ). SEJ is a protein of 269 amino acid residues which has substantial sequence similarity to the staphylococ cal A, E, D family of enterotoxins. The enterotoxin D and J open readi ng frames are transcribed in opposite directions and are separated by an 895 nucleotide intergenic region which contains a perfect inverted repeat, with each arm of the repeat having a length of 21 nucleotides. Chloramphenicol acetyl transferase (cat) transcriptional fusions were used to quantify expression from the enterotoxin gene promoters. Both enterotoxin genes are expressed in S. aureus. However, only sed is re gulated by the agr virulence gene signal transduction pathway. Western blot analyses utilizing anti-enterotoxin antisera have confirmed the results obtained with the ccir reporter system. PCR amplification stud ies suggest that the sej determinant may be present on all sed-encodin g plasmids. (C) 1998 Federation of European Microbiological Societies. Published by Elsevier Science B.V. All rights reserved.