Table 1 Cytolytic activity of PLY derivatives with mutations in the monomer-monomer interface.

From: Crystal structure of Streptococcus pneumoniae pneumolysin provides key insights into early steps of pore formation

Toxin

EC 50 (nM)

% Native PLY activity

PLY

0.013 ± 0.004

100.00

PLYK18A

ND

ND

PLYR208A

0.52 ± 0.07

2.50

PLYN66W

0.026 ± 0.01

50.00

PLYS68W

0.013 ± 0.005

100.00

PLYN66W∙S68W

2.03 ± 0.47

<1.00

PLYN66W∙S68W∙R208A

2.98 ± 0.66

<1.00

  1. The mean effective concentration (EC50; the concentration of toxin required to lyse 50% of RBCs) and the standard error of the mean from a minimum of three experiments are shown for each toxin. The percentage cytolytic activity of each mutant relative to native PLY activity [(EC50 native PLY/EC50 mutant) × 100] is also shown. ND, not determined because an EC50 could not be calculated as the highest concentration of toxin did not achieve 100% hemolysis.
Back to article page