title: Enhancement of protein secretion in Saccharomyces cerevisiae by overproduction of Sso protein, a late-acting component of the secretory machinery.
abstract: 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 alpha-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 alpha-amylase was demonstrated by modulating the expression level of the SSO2 gene. Quantitation of the alpha-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 efficiently 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.
authors.affiliation: VTT Biotechnology and Food Research, Espoo, Finland.
authors.forename: L
authors.initials: L
authors.lastname: Ruohonen
authors.forename: J
authors.initials: J
authors.lastname: Toikkanen
authors.forename: V
authors.initials: V
authors.lastname: Tieaho
authors.forename: M
authors.initials: M
authors.lastname: Outola
authors.forename: H
authors.initials: H
authors.lastname: Soderlund
authors.forename: S
authors.initials: S
authors.lastname: Keranen
mesh_terms: D001407:Bacillus / Q000201:enzymology; D002480:Cellulase / Q000378:metabolism; D005656:Fungal Proteins / Q000096:biosynthesis* / Q000235:genetics; D015966:Gene Expression Regulation, Fungal / Q000502:physiology; D006026:Glycoside Hydrolases / Q000096:biosynthesis / Q000235:genetics / Q000378:metabolism*; D008565:Membrane Proteins / Q000096:biosynthesis* / Q000235:genetics; D050765:Qa-SNARE Proteins; D012331:RNA, Fungal / Q000032:analysis; D012333:RNA, Messenger / Q000032:analysis; D011993:Recombinant Fusion Proteins / Q000096:biosynthesis / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000201:enzymology / Q000235:genetics / Q000378:metabolism*; D029701:Saccharomyces cerevisiae Proteins; D000516:alpha-Amylases / Q000096:biosynthesis / Q000235:genetics / Q000378:metabolism*; D043324:beta-Fructofuranosidase
chemical_list: D005656:Fungal Proteins; D008565:Membrane Proteins; D050765:Qa-SNARE Proteins; D012331:RNA, Fungal; D012333:RNA, Messenger; D011993:Recombinant Fusion Proteins; C084006:SSO1 protein, S cerevisiae; C084007:SSO2 protein, S cerevisiae; D029701:Saccharomyces cerevisiae Proteins; D006026:Glycoside Hydrolases; D000516:alpha-Amylases; D043324:beta-Fructofuranosidase; D002480:Cellulase