STREPTOKINASE SECRETION BY SERRATIA-MARCESCENS SIGNALED BY THE C-TERMINAL-41 AMINO-ACID SEGMENT OF METALLOPROTEASE

In order to investigate the secretion signal of Serratia marcescens me talloprotease (SMP) and examine the ability of the secretion signal to secrete foreign proteins, hybrid genes encoding the passenger-SMP C-t erminal segments were constructed. As a passenger protein, streptokina se (SK) deprived of its signal peptide was used. Three kinds of SMP C- terminal segments containing 41, 80, or 220 amino acid residues were f used to the C-terminus of SK as secretion signals. The SK-SMP chimeric proteins containing 41 or 220 amino acid segments of the SMP C-termin us were secreted into the culture medium by the SMP transporter of S. marcescens. This result suggests that cytoplasmic SK is secreted into the external medium by the C-terminal segments of SMP and also shows t hat the smallest, 41 amino acid segment of the SMP C-terminus function s as a secretion signal of foreign proteins as well as SMP. Key words: streptokinase, chimeric proteins, secretion signal, metalloprotease, Serratia marcescens.