Overproduction of Mpd2p suppresses the lethality of protein disulfide isomerase depletion in a CXXC sequence dependent manner.
Tachikawa H., Funahashi W., Takeuchi Y., Nakanishi H., Nishihara R., Katoh S., Gao X.D., Mizunaga T., Fujimoto D.
The third multicopy suppressor gene of the PDI1 deletion from Saccharomyces cerevisiae, MPD2, was isolated and characterized. The MPD2 gene encodes a protein with a putative signal sequence, ER retention signal, and a disulfide isomerase active site like sequence. The amino acid sequence around the active site like sequence is similar to the thioredoxin-like domains of PDI and PDI related proteins, although the similarity is comparatively low. A delta-pdi1 strain over-producing Mpd2p showed slow growth and was sensitive to 1 mM dithiothreitol. Mpd2p can be detected in wild type cells and is a glycoprotein. Although the MPD2 gene was not essential for growth, overexpression of the gene partially restored the maturation defect of carboxypeptidase Y caused by the PDI1 deletion. Mutagenesis analysis revealed that Mpd2p can compensate for the loss of PDI with its CXXC sequence.
Biochem. Biophys. Res. Commun. 239:710-714(1997) [ PubMed | SRS | CiteXplore ]
