SIGNAL PEPTIDASE CLEAVAGE SITE IN THE PROCESSING OF PSEUDOMONAS-AERUGINOSA PREPROELASTASE

The extracellular elastase (33 kDa) of Pseudomonas aeruginosa is synth esized as a 53.6-kDa preproenzyme containing a long N-terminal propept ide, which is processed to the mature form via a 51-kDa proelastase. A 51-kDa protein isolated from Escherichia coli transformant carrying t he Glu(141)-->Gln mutant elastase gene was subjected to N-terminal ami no acid sequence analysis. No autoproteolytic processing of proelastas e was expected to occur in these cells. The data indicated that the N- terminal sequence corresponds to the position between -174 and -164 of the preproelastase (numbers are in reference to the first amino acid residue of mature elastase). This confirms that the 51-kDa protein is proelastase and that the signal peptidase cleaves between Ala(-175) an d Ala(-174).