Identification of a bacteriophage containing a silent staphylococcal variant enterotoxin gene (sezA+).
A variant enterotoxin gene, referred to as sezA+, has been identified. Staphylococcus aureus FRI1106, a staphylococcal enterotoxin type D producer (Sed+), contained HindIII fragments of 3.8 and 9.4 kilobase pairs (kbp) that hybridized in Southern blot analysis to a probe containing only staphylococcal enterotoxin type A structural gene sequences. Presumably, probe A-624 hybridized to the 9.4-kbp HindIII fragment because of the sequence homology between sea+ and sed+. This 9.4-kbp HindIII fragment, which was part of a staphylococcal plasmid, was isolated and ligated into an Escherichia coli plasmid vector; Sed+ E. coli recombinant clones were isolated. The 3.8-kbp HindIII fragment was shown to be part of a viable lysogenic bacteriophage, and it contained sezA+. This sezA(+)-containing fragment was cloned into E. coli, and its DNA sequence was determined. Examination of the nucleotide sequence revealed a 771-bp region that contained an open reading frame with 85 and 77% nucleotide and derived amino acid sequence identifies with sea+ and staphylococcal enterotoxin type A, respectively. This open reading frame has 83 to 50% nucleotide sequence identities with the other types of staphylococcal enterotoxin genes. sezA+ was shown to be transcribed into stable mRNA. However, the sezA+ mRNA was not translated into an enterotoxinlike protein because it lacks an appropriate translation initiation codon.
Soltis
M T
MT
Department of Bacteriology, University of Wisconsin-Madison 53706.
Mekalanos
J J
JJ
Betley
M J
MJ
D000595:Amino Acid Sequence; D001427:Bacterial Toxins / Q000235:genetics*; D001483:Base Sequence; D015152:Blotting, Northern; D015139:Blotting, Southern; D003001:Cloning, Molecular; D004768:Enterotoxins / Q000235:genetics*; D015870:Gene Expression; D005814:Genes, Viral; D008969:Molecular Sequence Data; D011401:Promoter Regions, Genetic; D012333:RNA, Messenger / Q000235:genetics; D013204:Staphylococcus Phages / Q000235:genetics*; D013211:Staphylococcus aureus / Q000235:genetics*; D015678:Viral Structural Proteins / Q000235:genetics
D001427:Bacterial Toxins; D004768:Enterotoxins; D012333:RNA, Messenger; D015678:Viral Structural Proteins