The crucial amino acid residue related to inactivation of Vibrio vulnificus hemolysin.
Vibrio vulnificus, an opportunistic human pathogen causing fetal septicemia, produces a 50-kDa pore-forming toxin as a virulence factor. This toxin consists of 451 amino acid residues; however, there are two types of this toxin on the basis of the difference of some amino acid residues, type 1 (Leu(281), Ser(415), Asn(435)/Asp(435), Asn(438)) and type 2 (Ile(281), Asn(415), Asn(435), Thr(438)). In the present study, two characteristic properties of type 2 toxin that was elaborated by V. vulnificus cells or synthesized by the in vitro system were compared to those of type 1 toxin. Type 2 toxin was found to be more resistant to spontaneous inactivation at 37 degrees C and to specific inactivation by cholesterol. On the other hand, a variant of type 2 toxin (Asp(435), Asn(438)) showed the same properties as type 1 toxin. The replacement of the 438th Asn to Thr (N438T), but not the 435th Asp to Asn (D435N), resulted in reversion of the variant type 2 toxin to typical type 2 toxin. These findings indicate that a single amino acid residue, Thr(438), may be critical for higher stability of type 2 toxin.
Senoh
Mitsutoshi
M
Graduate School of Natural Science and Technology, Okayama University, Tsushima-Naka, Okayama, Japan.
Okita
Yuka
Y
Shinoda
Sumio
S
Miyoshi
Shin-ichi
S
D000596:Amino Acids / Q000502:physiology; D000818:Animals; D000907:Antibodies, Bacterial / Q000378:metabolism; D001426:Bacterial Proteins / Q000502:physiology*; D002784:Cholesterol / Q000494:pharmacology; D004912:Erythrocytes / Q000382:microbiology; D006460:Hemolysin Proteins / Q000187:drug effects / Q000235:genetics / Q000502:physiology*; D006461:Hemolysis / Q000502:physiology*; D008826:Microbial Sensitivity Tests / Q000379:methods; D012756:Sheep; D041261:Vibrio vulnificus / Q000235:genetics* / Q000472:pathogenicity*
D000596:Amino Acids; D000907:Antibodies, Bacterial; D001426:Bacterial Proteins; D006460:Hemolysin Proteins; D002784:Cholesterol