Enhancement of Protein Secretion inSaccharomyces cerevisiae by Overproduction of Sso Protein, a Late-acting Component of the Secretory Machinery
✍ Scribed by RUOHONEN, LAURA; TOIKKANEN, JAANA; TIEAHO, VILLE; OUTOLA, MIKA; SODERLUND, HANS; KERANEN, SIRKKA
- Publisher
- John Wiley and Sons
- Year
- 1997
- Tongue
- English
- Weight
- 434 KB
- Volume
- 13
- Category
- Article
- ISSN
- 0749-503X
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✦ Synopsis
Increased production of secreted proteins in Saccharomyces cerevisiae was achieved by overexpressing the yeast syntaxins, Sso1 or Sso2 protein, the t-SNAREs functioning at the targeting/fusion of the Golgi-derived secretory vesicles to the plasma membrane. Up to four-or six-fold yields of a heterologous secreted protein, Bacillus -amylase, or an endogenous secreted protein, invertase, were obtained respectively when expressing either one of the SSO genes, SSO1 or SSO2, from the ADH1 promoter on a multicopy plasmid. Direct correlation between the Sso protein level and the amount of secreted -amylase was demonstrated by modulating the expression level of the SSO2 gene. Quantitation of the -amylase activity in the culture medium, periplasmic space and cytoplasm suggests that secretion into the periplasmic space is the primary stage at which the SSO genes exert the secretion-enhancing function. Pulse-chase data also support enhanced secretion efficiency obtained by SSO overexpression. Our data suggest that the Sso proteins may be rate-limiting components of the protein secretion machinery at the exocytosis step in yeast. ( 1997 by