Characterization of a Saccharomyces cerevisiae mutant with oversecretion phenotype

Area of Science:

• Biotechnology
• Molecular Biology
• Yeast Genetics

Background:

• Saccharomyces cerevisiae is a widely used host for recombinant protein production.
• Optimizing secretion pathways is crucial for efficient heterologous protein expression.
• Glycosylation can impact protein activity and immunogenicity.

Purpose of the Study:

• To isolate and characterize an oversecreting mutant of Saccharomyces cerevisiae.
• To evaluate the potential of this mutant for enhanced foreign protein secretion.
• To investigate the genetic basis of the oversecretion and altered glycosylation phenotypes.

Main Methods:

• Meiotic segregation analysis of yeast strains.
• Transformation with mouse alpha-amylase cDNA.
• Quantification of alpha-amylase secretion and activity.
• Genetic analysis of mutant phenotypes.

Main Results:

• A novel Saccharomyces cerevisiae mutant (NI-C-D4) was isolated, exhibiting up to 13-fold increased secretion of mouse alpha-amylase.
• The secreted alpha-amylase showed higher activity and a higher proportion of the non-glycosylated form.
• A single chromosomal mutation was identified as responsible for both oversecretion and low-glycosylation phenotypes.
• The mutation is partially dominant and may involve a defect in ER-resident chaperone synthesis.

Conclusions:

• The identified Saccharomyces cerevisiae mutant (NI-C-D4) is a promising host for high-yield foreign protein production.
• The low-glycosylation phenotype is linked to oversecretion, suggesting a common regulatory mechanism.
• Further research into the specific chaperone defect could elucidate the underlying molecular mechanisms.