Title Active Site Aspartic Acid and Propeptide are Not Critical for the Activity and secretion of Serratia marcescens Serine Protease in Escherichia coli
Author Lee, Seung Whan · Kwon, Yong Tae · Rho, Hyune Mo *
Address Department of Molecular Biology and Research Center for Molecular Microbiology, Seoul National University
Bibliography Korean Journal of Microbiology, 32(6),552-557, 1994
Key Words Serratia marcescens, serine protease, secretion, OmpT signal peptide, aspartic acid, propeptide, toxicity
Abstract A serine protease (SMS) from Serratia marcescens RH1, which is produced as a 112kDa precursor composed of a typical NH_2-terminal signal peptide, a mature protease and a large COOH-terminal propeptide, was expressed by its own promoter and secreted extracellularly in Escherichia coli. Replacement of the SMS promoter and sifnal sequence by the φ10 promoter of bacteriophage T7 and OmpT signal sequence resulted in the secretion of active SMS in E, coli BL21(DE3). Deletion of the NH_2-terminal 54 amino acids containing Asp residue of the active site did not critically affect the activity and secretion of the protease. Furthermore, the deleted gene product lacking the entire propeptide was secreted as an active enzyme. Co-expressed mature protein and propeptide without covalent linkage were toxic to E, coli BL21(DE3) but not to E. coli HB101.
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