Open AccessIntracellular proteases in sporulated Bacillus thuringiensis subsp. kurstaki and their role in protoxin activation
Author(s) -
Kumar N.Suresh,
Venkateswerlu G.
Publication year - 1998
Publication title -
fems microbiology letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.899
H-Index - 151
eISSN - 1574-6968
pISSN - 0378-1097
DOI - 10.1111/j.1574-6968.1998.tb13915.x
Subject(s) - proteases , protease , biochemistry , bacillus thuringiensis , biology , bacillales , pmsf , enzyme , microbiology and biotechnology , chemistry , bacteria , bacillus subtilis , genetics
The intracellular proteases in sporulated Bacillus thuringiensis subsp. kurstaki were studied to identify the endogenous proteases involved in the activation of protoxin. The proteases obtained with 30% ammonium sulfate saturation were analysed by both gelatin zymography and azocasein hydrolysis. Three proteases with molecular mass 92 kDa, 78 kDa and 69 kDa were identified on gelatin gel and their gelatinolytic activity was inhibited by ethylenediamine tetraacetic acid. Significantly, 1,10‐phenanthroline caused an inhibition of the azocasein hydrolytic activity by 98% and ethylenediamine tetraacetic acid by 28%. The three proteases were heat‐stable at 65 °C, while the 69‐kDa protease was active up to 75 °C. Intracellular protease‐deficient mutants (ethyl methanesulfonate mutagenesis) could not generate the active toxin suggesting the existence of a specific enzyme affecting the conversion of protoxin to toxin.