Amino acids in pneumolysin important for hemolytic activity identified by random mutagenesis

The structural gene of pneumolysin was randomly mutagenized. A screen, developed to identify mutants with reduced hemolytic activity, identified substitutions within the cysteine-containing region and also at residues toward the N terminus of the toxin. These are the first reported changes within the N-terminal region of the toxin that affect cytolytic activity.