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| The Molecular Design, Cloning of Model Antimicrobial Peptide PGYa and its Secreted Expression in Pichia pastoris |
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Abstract Based on sequence analogy and amphipathicity analyse of α-helical antimicrobial peptides, a sequence template was extracted. The model Antimicrobial Peptide PGYa(peptide beginning with Gly and ending with Tyr-NH2) was designed by virtue of the template and computer-aided design subsequently. Using the optimal condon of Pichia pastoris, PGYa gene with 94bp length were achieved through a recursive PCR strategy. Especially a Kex2 signal cleavage site was fused in 5’end of the antibacterial peptide gene to make sure the expression protein with nature N-terminal. The modified antibacterial peptide gene was then cloned into the pPICZα-A vector to construct the recombinant expression vector pPICZα-A- PGYa, and transformed into yeast host strain X-33. Under the control of the promoter AOX1(alcohol oxidase 1), the PGYa protein with a molecular weight of 2.8 KD was expressed in supernatant and the amount of secreted pertein can reach 132 μg/mL. Preliminary antibacterial assays showed that PGYa has a potent antibacterial activity against E.coli DH5α.
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Received: 22 May 2007
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