Protein disulfide isomerase is essential for viability in Saccharomyces cerevisiae.
Protein disulfide isomerase (PDI) is an enzyme involved in the catalysis of disulfide bond formation in secretory and cell-surface proteins. Using an oligodeoxyribonucleotide designed to detect the conserved 'thioredoxin-like' active site of vertebrate PDIs, we have isolated a gene encoding PDI from the lower eukaryote, Saccharomyces cerevisiae. The nucleotide sequence and deduced open reading frame of the cloned gene predict a 530-amino-acid (aa) protein of Mr 59,082 and a pI of 4.1, physical properties characteristic of mammalian PDIs. Furthermore, the aa sequence shows 30-32% identity with mammalian and avian PDI sequences and has a very similar overall organisation, namely the presence of two approx. 100-aa segments, each of which is repeated, with the most significant homologies to mammalian and avian PDIs being in the regions (a, a') that contain the conserved 'thioredoxin-like' active site. The N-terminal region has the characteristics of a cleavable secretory signal sequence and the C-terminal four aa (-His-Asp-Glu-Leu) are consistent with the protein being a component of the S. cerevisiae endoplasmic reticulum. Transformants carrying multiple copies of this gene (designated PDI1) have tenfold higher levels of PDI activity and overproduce a protein of the predicted Mr. The PDI1 gene is unique in the yeast genome and encodes a single 1.8-kb transcript that is not found in stationary phase cells. Disruption of the PDI1 gene is haplo-lethal indicating that the product of this gene is essential for viability.
Farquhar
R
R
Biological Laboratory, University of Kent, Canterbury, U.K.
Honey
N
N
Murant
S J
SJ
Bossier
P
P
Schultz
L
L
Montgomery
D
D
Ellis
R W
RW
Freedman
R B
RB
Tuite
M F
MF
D000595:Amino Acid Sequence; D001483:Base Sequence; D001665:Binding Sites / Q000235:genetics; D015152:Blotting, Northern; D003001:Cloning, Molecular; D004220:Disulfides / Q000378:metabolism; D015870:Gene Expression / Q000235:genetics; D007535:Isomerases / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D008969:Molecular Sequence Data; D019704:Protein Disulfide-Isomerases; D012441:Saccharomyces cerevisiae / Q000201:enzymology* / Q000235:genetics / Q000254:growth & development; D012689:Sequence Homology, Nucleic Acid; D013879:Thioredoxins / Q000737:chemistry / Q000235:genetics
D004220:Disulfides; D013879:Thioredoxins; D007535:Isomerases; D019704:Protein Disulfide-Isomerases