Vol. 200, No. 1, July 5, 2004. Pages 35–46.

Due to an arithmetic error, an active site Serine residue at position 272 in the deduced amino acid sequence of the A subunit of the toxin described in this paper was incorrectly stated as being at position 271. This has resulted in incorrect terminology for the critical residue and for mutations introduced at this position, as listed below.

codon 271 should be codon 272 on page 37

S271 should be S272 on pages 37 and 40

Ser271-Ala should be Ser272-Ala on page 45

pK184subAA271B should be pK184subAA272B throughout

SubAA271B should be SubAA272B in Figure 8 B

The residue numbers of the terminal amino acids of the Ser catalytic domain (269 and 279) should be 270 and 280 in Figure 2.