Immunobiologic and biochemical properties of mutants of toxic shock syndrome toxin-1.
Toxic shock syndrome (TSS) is a multisystem illness caused mainly by Staphylococcus aureus producing TSS toxin-1 (TSST-1). A variant of TSST-1 has been isolated from ovine mastitis S. aureus. This toxin, TSST-ovine (TSST-O) is only weakly T cell mitogenic, is nonpyrogenic, does not enhance endotoxin shock, and does not cause TSS in the miniosmotic pump model. The sequence of the ovine gene (tstO) differs from the TSST-1 gene (tstH) by 14 nucleotides that change seven amino acids in the mature protein of which two are in the C-terminal half. A gene fusion containing half of both tstH and tstO was made and cloned into S. aureus. The fusion protein contained the two C-terminal amino acid differences that are in TSST-O at residues 132 and 140. The fusion protein was not T cell mitogenic and did not elicit TSS in two rabbit models. Additional experiments used mutagenesis to change the lysine residue at position 132 of TSST-O to glutamate (TSST-OK132E), as exists in TSST-1, and to change the lysine residue of the human-ovine fusion at position 132 to glutamate (TSST-11140T). Both mutants were pyrogenic, enhanced endotoxin shock, and caused TSS in the miniosmotic pump model. However, the proteins were only partially T cell mitogenic. The restoration of lethality of TSST-O and the human-ovine fusion by changing the lysine to glutamate, as exists in TSST-1, indicates that residue 132 is important in lethality. The failure to regenerate complete T cell mitogenicity of the same mutants indicates that residues 132 and 140 are important for that activity.
Murray
D L
DL
Department of Microbiology, University of Minnesota Medical School, Minneapolis 55455.
Prasad
G S
GS
Earhart
C A
CA
Leonard
B A
BA
Kreiswirth
B N
BN
Novick
R P
RP
Ohlendorf
D H
DH
Schlievert
P M
PM
D000595:Amino Acid Sequence; D000818:Animals; D001427:Bacterial Toxins; D001483:Base Sequence; D004768:Enterotoxins / Q000235:genetics / Q000502:physiology* / Q000633:toxicity; D008934:Mitogens; D008969:Molecular Sequence Data; D009154:Mutation; D017433:Protein Structure, Secondary; D011817:Rabbits; D011993:Recombinant Fusion Proteins / Q000633:toxicity; D017386:Sequence Homology, Amino Acid; D012772:Shock, Septic / Q000209:etiology; D013211:Staphylococcus aureus / Q000235:genetics; D013329:Structure-Activity Relationship; D018089:Superantigens
D001427:Bacterial Toxins; D004768:Enterotoxins; D008934:Mitogens; D011993:Recombinant Fusion Proteins; D018089:Superantigens; C030107:enterotoxin F, Staphylococcal