Oxidative Activity of Yeast Ero1p on Protein Disulfide Isomerase and Related Oxidoreductases of the Endoplasmic Reticulum

• Published in: The Journal of biological chemistry Vol. 285; no. 24; pp. 18155 - 18165
• Main Authors: Vitu, Elvira, Kim, Sunghwan, Sevier, Carolyn S., Lutzky, Omer, Heldman, Nimrod, Bentzur, Moran, Unger, Tamar, Yona, Meital, Kaiser, Chris A., Fass, Deborah
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 11-06-2010; American Society for Biochemistry and Molecular Biology
• Subjects: Catalysis; Catalytic Domain; Cell Biology; Disulfides - chemistry; Electron Transfer; Endoplasmic Reticulum - enzymology; Enzymes/Flavin; Enzymes/Oxidase; Enzymology; Flavins - chemistry; Genetic Variation; Glutathione; Glutathione - metabolism; Glycoproteins - metabolism; Mutation; Organisms/Yeast; Oxidoreductases Acting on Sulfur Group Donors - metabolism; Oxygen - chemistry; Oxygen - metabolism; Protein Disulfide-Isomerases - metabolism; Protein Folding; Protein Structure, Tertiary; Saccharomyces cerevisiae - genetics; Saccharomyces cerevisiae Proteins - metabolism; Subcellular Organelles/Endoplasmic Reticulum; Sulfhydryls/Disulfide; Temperature; Organisms/Yeast; Subcellular Organelles/Endoplasmic Reticulum; Electron Transfer; Enzymes/Flavin; Enzymes/Oxidase; Sulfhydryls/Disulfide; Glutathione
• ISSN: 0021-9258; 1083-351X
• DOI: 10.1074/jbc.M109.064931

The sulfhydryl oxidase Ero1 oxidizes protein disulfide isomerase (PDI), which in turn catalyzes disulfide formation in proteins folding in the endoplasmic reticulum (ER). The extent to which other members of the PDI family are oxidized by Ero1 and thus contribute to net disulfide formation in the ER has been an open question. The yeast ER contains four PDI family proteins with at least one potential redox-active cysteine pair. We monitored the direct oxidation of each redox-active site in these proteins by yeast Ero1p in vitro. In this study, we found that the Pdi1p amino-terminal domain was oxidized most rapidly compared with the other oxidoreductase active sites tested, including the Pdi1p carboxyl-terminal domain. This observation is consistent with experiments conducted in yeast cells. In particular, the amino-terminal domain of Pdi1p preferentially formed mixed disulfides with Ero1p in vivo, and we observed synthetic lethality between a temperature-sensitive Ero1p variant and mutant Pdi1p lacking the amino-terminal active-site disulfide. Thus, the amino-terminal domain of yeast Pdi1p is on a preferred pathway for oxidizing the ER thiol pool. Overall, our results provide a rank order for the tendency of yeast ER oxidoreductases to acquire disulfides from Ero1p.