Cytotoxic activities of Leptospira interrogans hemolysin SphH as a pore-forming protein on mammalian cells.
Leptospirosis is a spirochetal zoonosis that causes an acute febrile systemic illness in humans. Leptospira sp. hemolysins have been shown to be virulence factors for the pathogenesis of leptospirosis. Previously, we cloned a hemolysin SphH of Leptospira interrogans serovar lai, a homologue of L. borgpetersenii sphingomyelinase (SphA), from a genomic library (S. H. Lee, K. A. Kim, Y. K. Kim, I. W. Seong, M. J. Kim, and Y. J. Lee, Gene 254:19-28, 2000). Escherichia coli lysate harboring the sphH showed high hemolytic activities on sheep erythrocytes. However, it neither showed sphingomyelinase nor phospholipase activities, in contrast to SphA which was known to have sphingomyelinase activity. Interestingly, the SphH-mediated hemolysis on erythrocytes was osmotically protected by PEG 5000, suggesting that the SphH might have caused pore formation on the erythrocyte membrane. In the present study, we have prepared the Leptospira hemolysin SphH and investigated its hemolytic and cytotoxic activities on mammalian cells. SphH was shown to be a pore-forming protein on several mammalian cells: When treated with the SphH, the sheep erythrocyte membranes formed pores, which were morphologically confirmed by transmission electron microscopy. Furthermore, the SphH-mediated cytotoxicities on mammalian cells were demonstrated by the release of LDH and by inverted microscopic examinations. Finally, the immune serum against the full-length hemolysin could effectively neutralize the SphH-mediated hemolytic and cytotoxic activities. In conclusion, these results suggest that the virulence of Leptospira SphH was due to the pore formation on mammalian cell membranes.
Lee
Seoung Hoon
SH
Division of Infectious Diseases, Department of Internal Medicine, Graduate School of Biomedical Sciences, College of Medicine, Korea University, Seoul 136-705, Republic of Korea.
Kim
Sangduk
S
Park
Seung Chul
SC
Kim
Min Ja
MJ
D000818:Animals; D000907:Antibodies, Bacterial / Q000096:biosynthesis; D001426:Bacterial Proteins; D002460:Cell Line; D002462:Cell Membrane / Q000473:pathology / Q000648:ultrastructure; D002522:Chlorocebus aethiops; D004912:Erythrocytes / Q000473:pathology / Q000648:ultrastructure; D006460:Hemolysin Proteins / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D006461:Hemolysis; D006801:Humans; D007921:Leptospira interrogans / Q000235:genetics / Q000378:metabolism*; D008322:Mammals; D008854:Microscopy, Electron / Q000379:methods; D009500:Neutralization Tests; D011817:Rabbits; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism; D012756:Sheep; D014407:Tumor Cells, Cultured; D014709:Vero Cells
D000907:Antibodies, Bacterial; D001426:Bacterial Proteins; D006460:Hemolysin Proteins; D011993:Recombinant Fusion Proteins; C443499:SphH protein, Leptospira interrogans