Proteases Produced by a Proteolytic Mutant of Clostridium botulinum Type E

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Abstract
A proteolytic mutant from C. botulinum type E produced extracellular proteases after the end of exponential growth coinciding with the period of sporulation. Proteases were separated into 4 fractions by chromatography on a DEAE-cellulose column. One was a SH-dependent protease that also apparently required a divalent cation for enzyme activity since it was inhibited by EDTA. This enzyme hydrolyzed synthetic amide and ester compounds containing an arginine residue, and showed some activity towards L-lysine methyl ester. Apparently, 2 of the other proteases were serine proteases and the 4th was a metal protease. These last 3 proteases did not require a thiol agent and did not hydrolyze any of the synthetic amides or esters examined. Only the SH-dependent protease could activate C. botulinum type B, E and F toxins. The ability of this enzyme to activate type B and E toxins was markedly lower than that of trypsin. The susceptibility of type B toxin to this protease was lower than that of type E toxin. C2 toxin was not activated by this enzyme. The SH-dependent protease in this proteolytic mutant of C. botulinum type E probably has properties similar to those of proteases from C. botulinum types B and F.