Codous optimization and high-level expression of hepatitis B virus S gene in Pichia pastoris

Abstract

Objective To synthesize hepatitis B virus S gene which is suitable for yeast protein expression and express hepatitis B virus S protein in Pichia pastoris. Methods Synonymous codons preferred by yeast usage on protein expression were used to replace some native codons of wild-type HBV S gene.Synthetic S gene (synS-gene) was achieved by a recursive PCR (rPCR). The synS-gene was inserted into the yeast expression vector pPICZB. Recombinant plasmid was transformed into KM71H yeast by electroparation. The yeast transformant induced by methanol expressed the S protein. Results The restriction analysis and DNA sequencing confirmed that the synS-gene was inserted into yeast pPICZB in correct orientation. SDS-PAGE and ELISA indicated that the S protein was expressed by the yeast transformant. The expression level of S protein in the strain containing synS-gene was more higher than the strain containing wild-type S-gene. Conclusion Codons optimization can promote the yield of recombinant S protein in Pichia pastoris. Key words: Hepatitis B virus;  S protein;  Preferred codoas;  Pichia