title: Functional differences between human and yeast protein disulfide isomerase family proteins.
abstract: Previously, it has been reported that a mammalian protein disulfide isomerase (PDI), when expressed on a single copy number plasmid, can rescue growth of a PDI1-disrupted yeast. However, here, for the first time we demonstrated by tetrad analysis that human PDI (hPDI) is unable to replace yeast PDI (yPDI) when hPDI cDNA is integrated into the yeast chromosome. This observation indicates that hPDI is not functionally equivalent to yPDI. Estimation of the actual copy number of the plasmid, as well as comparison of isomerase and chaperone activities between human and yeast PDI homologues, indicates that one copy of hPDI cDNA is not sufficient to rescue the PDI1-disrupted strain. Notably, the isomerase activities of yPDI family proteins, Mpd1p, Mpd2p, and Eug1p, were extremely low, although yPDI itself exhibited twice as much isomerase activity as hPDI in vitro. Moreover, with the exception of Mpd1p, all hPDI and yPDI family proteins had chaperone activity, this being particularly strong in the case of yPDI and Mpd2p. These observations indicate that the growth of Saccharomyces cerevisiae is completely dependent on the isomerase activity of yPDI.
authors.affiliation: Department of Bioscience and Technology, Faculty of Science and Engineering, Ritsumeikan University, 1-1-1 Noji-higashi, Kusatsu, Shiga 525-8577, Japan.
authors.forename: Taiji
authors.initials: T
authors.lastname: Kimura
authors.forename: Yasuhiro
authors.initials: Y
authors.lastname: Hosoda
authors.forename: Yukiko
authors.initials: Y
authors.lastname: Kitamura
authors.forename: Hideshi
authors.initials: H
authors.lastname: Nakamura
authors.forename: Tomohisa
authors.initials: T
authors.lastname: Horibe
authors.forename: Masakazu
authors.initials: M
authors.lastname: Kikuchi
mesh_terms: D001483:Base Sequence; D017931:DNA Primers; D018076:DNA, Complementary; D006801:Humans; D019704:Protein Disulfide-Isomerases / Q000235:genetics / Q000378:metabolism*; D012441:Saccharomyces cerevisiae / Q000201:enzymology*; D013045:Species Specificity
chemical_list: D017931:DNA Primers; D018076:DNA, Complementary; D019704:Protein Disulfide-Isomerases