Characterization of a gene encoding a Pichia pastoris protein disulfide isomerase

Protein disulphide isomerases belong to the thioredoxin superfamily of prot ein-thiol oxidoreductases that have two double-cysteine redox-active sites and take part in protein folding in the endoplasmic reticulum (ER). We repo rt here the cloning of a Pichia pastoris genomic DNA fragment (2919 bp) tha t encodes the full length of a protein disulphide isomerase (PpPDI). The de duced amino acid sequence of PDI consists of 517 residues and carries the t wo characteristic PDI-type redox-active domains -CGHC-, separated by 338 re sidues, and two potential N-glycosylation sites. The N-terminal end forms a putative signal sequence, and an acidic C-terminal region represents a pos sible calcium-binding domain. Together with the -HDEL ER retrieval sequence at the C-terminus, these features indicate that the gene encodes a redox-a ctive ER-resident protein disulphide isomerase. The nucleotide sequence, wh ich also contains two other open reading frames, has been submitted to the EMBL Nucleotide Sequence Database, Accession No. AJ302014. (C) 2001 Academi c Press.