Essential role of domain 4 of pneumolysin from Streptococcus pneumoniae in cytolytic activity as determined by truncated proteins.
Pneumolysin (PLY), an important virulence factor of Streptococcus pneumoniae, is one of the members of thiol-activated cytolysins (TACYs) consisting of four domains. TACYs commonly bind to membrane cholesterol and oligomerize to form transmembrane pore. We have constructed full-length and various truncated PLYs to study the role of domains of PLY in the cytolytic activity. Full-length PLY had binding ability to both cell membrane and immobilized cholesterol. A truncated PLY which comprised only domain 4 molecule, the C-terminal domain of PLY, sustained the binding ability to cell membrane and cholesterol, whereas domain 1-3 molecule had no binding ability to them. Furthermore, the domain 4 molecule inhibited both the membrane binding and the hemolytic activity of full-length PLY. Accordingly, the present results provided the direct evidence that domain 4 was essential for the initial binding to membrane cholesterol and the interaction led to the subsequent membrane damage process.
Baba
H
H
Department of Microbiology, Kyoto University Graduate School of Medicine, Sakyo-ku, Kyoto, 606-8501, Japan.
Kawamura
I
I
Kohda
C
C
Nomura
T
T
Ito
Y
Y
Kimoto
T
T
Watanabe
I
I
Ichiyama
S
S
Mitsuyama
M
M
D000818:Animals; D001426:Bacterial Proteins; D002462:Cell Membrane / Q000378:metabolism; D002784:Cholesterol / Q000378:metabolism; D002855:Chromatography, Thin Layer; D004305:Dose-Response Relationship, Drug; D004912:Erythrocytes / Q000378:metabolism; D006461:Hemolysis; D008024:Ligands; D010957:Plasmids / Q000378:metabolism; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D011994:Recombinant Proteins / Q000378:metabolism; D012756:Sheep; D013296:Streptococcus pneumoniae / Q000737:chemistry*; D013301:Streptolysins / Q000737:chemistry*
D001426:Bacterial Proteins; D008024:Ligands; D011994:Recombinant Proteins; D013301:Streptolysins; C032290:plY protein, Streptococcus pneumoniae; D002784:Cholesterol