J. Biol. Chem., Vol. 261, Issue 22, 10176-10181, 08, 1986
Determination of the signal peptidase cleavage site in the preprosubtilisin of Bacillus subtilis
SL Wong and RH Doi
Bacillus subtilis subtilisin is predicted to be synthesized as a
preproenzyme according to the sequence analysis of its gene. We have
synthesized the [35S] methionine-labeled preprosubtilisin in vitro and
processed the precursor to prosubtilisin by the addition of membrane
vesicles derived from vegetative cells of B. subtilis and Triton X-100.
Radiosequencing of the prosubtilisin allowed the precise determination of
the signal peptidase cleavage site. The preprosubtilisin was found to have
a 29-amino-acid-long signal peptide with the signal peptidase cleavage
sequence of AlaGln-AlaAla. Fusion of the signal peptide sequence to the
mature TEM beta-lactamase structural gene allowed the production of an
active and secreted form of beta-lactamase in vivo. An N-terminal sequence
analysis of this product indicated that the observed in vivo signal
peptidase cleavage site was exactly the same as that determined by in vitro
analysis. During the development of the in vitro processing system, we
demonstrated that the replacement of the subtilisin transcription
regulatory sequence by a vegetative promoter allowed the vegetative
expression and secretion of subtilisin. Thus, the late expression of the
native subtilisin gene is mainly controlled at the transcription level and
the secretion/processing systems are available for vegetative production of
subtilisin.