Effect of EPS1 gene deletion in Saccharomyces cerevisiae on the secretion of foreign proteins which have disulfide bridges

Both amyloid-prone cystatin and unstable mutant C94A lysozyme were secreted in wild-type and Delta eps1 Saccharomyces cerevisiae cells. Amyloid-prone cystatin secreted at much higher level in Delta eps1 cells than that in wild-type yeast. In parallel, the secretion amount of disulfide bond disrupted mutant C94A lysozyme greatly increased in Delta eps1 cells although that was apparently low in wild-type yeast cells compared with the secretion amount of wild-type lysozyme. It is interesting that neither the unstable mutant C94A lysozyme nor amyloid-prone cystatin secreted in Delta eps1 cells maintained their specific activities. These observations lead to the supposition that yeast cells deficient for the protein disulfide isomerase-family-member EPS1 locus secrete more of labile disulfide-containing model proteins. (c) 2005 Federation of European Biochemical Societies. Published by Elsevier B.V. All rights reserved.