Yeast Protein Expression Case Studies | Pichia pastoris & S. cerevisiae | AtaGenix

Pichia pastoris | Enzyme Production

High-Yield Secreted Enzyme for Industrial Biocatalysis

Biotech Client (NDA) | Industrial Enzyme Program

Challenge: The client required gram-per-liter yields of a thermostable hydrolase with native disulfide bonds intact. E. coli expression produced insoluble inclusion bodies with no detectable activity.

Solution: AtaGenix performed codon optimization for P. pastoris, constructed an AOX1-driven secretion vector with alpha-factor signal peptide, and screened 96 transformants in deep-well plates to identify high-secreting clones. Fed-batch fermentation was optimized at 5 L scale.

Results: Lead clone achieved secreted expression at 1.2 g/L in fed-batch culture. Purified enzyme retained full catalytic activity (>95% of native control) with correct disulfide bond formation confirmed by non-reducing SDS-PAGE. Endotoxin < 0.1 EU/ug.

Pichia pastoris | Diagnostic Antigen

Glycosylated Viral Antigen for Serological Assay Development

Diagnostics Company (NDA) | Infectious Disease Panel

Challenge: A viral envelope glycoprotein was needed as a capture antigen for ELISA-based serological screening. The protein required partial glycosylation for proper epitope presentation, but mammalian-derived glycoforms led to non-specific binding in human serum samples.

Solution: AtaGenix expressed the target in P. pastoris using a GAP constitutive promoter for consistent yield, combined with alpha-factor-mediated secretion. High-mannose glycosylation from yeast reduced the cross-reactivity observed with mammalian-expressed protein. Multi-step chromatography (IMAC + SEC) delivered high-purity antigen.

Results: Purified antigen at 450 mg/L with >98% monomer content (analytical SEC). In paired ELISA testing, the yeast-derived antigen showed 40% lower background signal versus the mammalian counterpart, improving assay specificity without sacrificing sensitivity.

S. cerevisiae | VLP Display

Yeast Surface Display for Antibody Screening Antigen

Academic Research Institute (NDA) | Immunology Program

Challenge: A research group needed a conformationally intact multi-pass transmembrane receptor as an immunization antigen. Soluble ectodomains expressed in E. coli failed to elicit antibodies recognizing the native receptor on cell surfaces.

Solution: AtaGenix utilized S. cerevisiae surface display (Aga2p fusion) to present the receptor extracellular domain in a membrane-anchored, conformationally native context. Displayed yeast particles were used directly as immunogens for subsequent antibody generation campaigns.

Results: Flow cytometry confirmed high-level surface display (>60% positive cells). Immunized animals produced serum antibodies that recognized native receptor on mammalian cell lines by flow cytometry and immunofluorescence — a significant improvement over the soluble antigen approach.

Start Your Yeast Expression Project

Share your target sequence, desired yield, and application requirements. Our PhD project managers will evaluate feasibility and recommend the optimal yeast host, promoter, and purification strategy — typically within 48 hours.

AtaGenix supports both Pichia pastoris (AOX1 and GAP promoters) and Saccharomyces cerevisiae expression, with end-to-end service from codon optimization through QC-released purified protein.