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영어
Hepatitis B virus causes the acute and chronic liver diseases. The gene coding for the S domain of hepatitis B virus surface antigen (sHBsAg) fused with the mating factor α (MFα) signal sequence was introduced by the chromosomal δ-integration to make S. cerevisiae 2805/pδMFα_sHBsAg strain. The sHBsAg gene was expressed under the control of the galactoseinducible GAL1 promoter. In this study, protein folding accessory proteins such as PDI1, SEC23, TRX2 and SCJ1 were coexpressed individually in recombinant S. cerevisiae 2805/pδMFα_sHBsAg to enhance the production of sHBsAg. Their coexpression led to a 2-fold increase each in the expression level of sHBsAg, compared to that of the control strain. The combinatorial expression of PDI1 and SEC23 gave a synergistic effect on the sHBsAg titer
and productivity. Also KEX2 protease was coexpressed to obtain intact sHBsAg. In a glucose-limited fed-batch fermentation with YPDG medium, 15.2 g/L of dry cell mass and 5.81 mg/g cell of specific sHBsAg content were obtained in recombinant S. cerevisiae 2805/ pδMFα_sHBsAg +pPDI1+ pSEC23+pKEX2, which were approximately 11 and 12 times higher than those of the control strain, respectively.