Erv1p from Saccharomyces cerevisiae is a FAD-linked sulfhydryl oxidase

The yeast ERV1 gene encodes a small polypeptide of 189 amino acids that is essential for mitochondrial function and for the viability of the cell. In this study we report the enzymatic activity of this protein as a flavin-linked sulfhydryl oxidase catalyzing the formation of disulfide bridges. Deletion of the amino-terminal part of Erv1p shows that the enzyme activity is located in the 15 kDa carboxy-terminal domain of the protein. This fragment of Erv1p still binds FAD and catalyzes the formation of disulfide bonds but is no longer able to form dimers like the complete protein. The carboxy-terminal fragment contains a conserved CXXC motif that is present in all homologous proteins from yeast to human. Thus Erv1p represents the first FAD-linked sulfhydryl oxidase from yeast and the first of these enzymes that is involved in mitochondrial biogenesis.