STREPTOMYCES-GRISEUS PROTEASE-B - SECRETION CORRELATES WITH THE LENGTH OF THE PROPEPTIDE

Streptomyces griseus protease B, a member of the chymotrypsin superfam ily, is encoded by a gene that expresses a pre-pro-mature protein. Dur ing secretion the precursor protein is processed into a mature, fully folded protease. In this study, we constructed a family of genes which encode deletions at the amino-terminal end of the propeptide. The sec retion of active protease B was seen to decrease in an exponential man ner according to the length of the deletion. The results underscore th e intimate relationship between folding and secretion in bacterial pro tease expression. They further suggest that the propeptide segment of the zymogen stabilizes the folding of the mature enzyme through many s mall binding interactions over the entire surface of the peptide rathe r than through a few specific contacts.