In Saccharomyces cerevisiae, we synthesized and secreted L-HBVsAg (named as pre-S(Met1 to Asn174)::S(Met175 to Ile400)) and three mutants, i.e., pre-S ○○::S (Asn15Gln and Asn123Gln), pre-S○○:: S○ (Asn15Gln, Asn123Gln, and Asn320Gln), and pre-S ○○::S○○ (Asn15Gln, Asn123Gln, Asn233Gln, and Asn320Gln). All of the secreted pre-S::S was N-glycosylated, i.e., hyper-mannosylated. In the secretion of pre-S○○::S and pre-S○○::S○, besides the hyper-mannosylated form, another immunoreactive protein with much lower molecular mass was observed, which seems to be unglycosylated form of pre-S○○::S and pre-S○○::S○. Only a part of the secreted pre-S○○::S or pre-S○○::S○ molecules was N-glycosylated, and the site for the partial N-glycosylation seems to be Asn233 in S-antigen region. Compared to the N-glycosylated pre-S ○○::S and pre-S○○::S○, pre-S○○::S○○ (non-N-glycosylated mutant) was secreted with lower secretion efficiency but showed apparent immunoreactivity to anti-S antigen monoclonal Ab. Interestingly, unlike pre-S○○::S○○ with authentic C-terminus, the recombinant pre-S○○::S○○ with C-terminal myc or poly-histidine tag (pre-S○○::S ○○::tag) was almost all aggregated into insoluble proteins in the intracellular region. Conclusively, the C-terminal sequence and glycosylation in S-antigen region seem to be of crucial importance in determining the secretion efficiency of L-HBVsAg in S. cerevisiae.
- C-terminus of S antigen
- Secretion efficiency
ASJC Scopus subject areas
- Applied Microbiology and Biotechnology