[Secreted expression of the combinant antimicrobial peptide PL in Pichia pastoris and its antibacterial activity in vitro].

In order to obtain a high activity antibacterial peptide, An expression vector pPICZalphaA-pl is constructed with a tandem of four antimicrobial peptides in the same direction,which includes Protegrin-1 (PG-1), Scorpion Defensin (SD), Metalnikowin-2A and Sheep Myeloid Antibacterial Peptide (SMAP-29) (serial number in GenBank are AAB27599, AAAB27538, P80409 and P49928 respectively). At the same time the expression vector pPICZalphaA-sd which express Scorpion Defensin was contructed. The expression vectors of pPICZalphaA-pl and pPICZalphaA-sd were linearized and transformed into the yeast host strain X-33 respectively. Under the control of the promoter AOX1 (alcohol oxidase1), the peptides PL and SD were secreted expressed. Their heat-stable property, acid-stable property and MIC were detected in vitro. The results suggest the peptides PL and SD have good heat-stable and acid-stable properties, and the combinant PL peptide showes higher antibacterial activity against several Gram-positive bacteria (G+) and Gram-negative bacteria (G-) than the peptide SD, especially against Escherichia coli. The antibacterial activity of combinant antimicrobial peptide PL shows its far exploiting perspective.