title: Distinct roles of protein disulfide isomerase and P5 sulfhydryl oxidoreductases in multiple pathways for oxidation of structurally diverse storage proteins in rice.
abstract: In the rice (Oryza sativa) endosperm, storage proteins are synthesized on the rough endoplasmic reticulum (ER), in which prolamins are sorted to protein bodies (PBs) called type-I PB (PB-I). Protein disulfide isomerase (PDI) family oxidoreductase PDIL2;3, an ortholog of human P5, contains a conserved structural disulfide in the redox-inactive thioredoxin-like (TRX) domain and was efficiently targeted to the surface of PB-I in a redox active site-dependent manner, whereas PDIL1;1, an ortholog of human PDI, was localized in the ER lumen. Complementation analyses using PDIL1;1 knockout esp2 mutant indicated that the a and a' TRX domains of PDIL1;1 exhibited similar redox activities and that PDIL2;3 was unable to perform the PDIL1;1 functions. PDIL2;3 knockdown inhibited the accumulation of Cys-rich 10-kD prolamin (crP10) in the core of PB-I. Conversely, crP10 knockdown dispersed PDIL2;3 into the ER lumen. Glutathione S-transferase-PDIL2;3 formed a stable tetramer when it was expressed in Escherichia coli, and the recombinant PDIL2;3 tetramer facilitated α-globulin(C79F) mutant protein to form nonnative intermolecular disulfide bonds in vitro. These results indicate that PDIL2;3 and PDIL1;1 are not functionally redundant in sulfhydryl oxidations of structurally diverse storage proteins and play distinct roles in PB development. We discuss PDIL2;3-dependent and PDIL2;3-independent oxidation pathways that sustain disulfide bonds of crP10 in PB-I.
authors.affiliation: Division of Plant Sciences, National Institute of Agrobiological Sciences, Tsukuba, Ibaraki 305-8602, Japan.
authors.forename: Yayoi
authors.initials: Y
authors.lastname: Onda
authors.forename: Ai
authors.initials: A
authors.lastname: Nagamine
authors.forename: Mutsumi
authors.initials: M
authors.lastname: Sakurai
authors.forename: Toshihiro
authors.initials: T
authors.lastname: Kumamaru
authors.forename: Masahiro
authors.initials: M
authors.lastname: Ogawa
authors.forename: Yasushi
authors.initials: Y
authors.lastname: Kawagoe
mesh_terms: D004721:Endoplasmic Reticulum / Q000378:metabolism; D056625:Endosperm / Q000378:metabolism; D055785:Gene Knockdown Techniques; D055786:Gene Knockout Techniques; D005816:Genetic Complementation Test; D009154:Mutation; D012275:Oryza / Q000201:enzymology* / Q000235:genetics; D010084:Oxidation-Reduction; D010088:Oxidoreductases / Q000378:metabolism*; D019704:Protein Disulfide-Isomerases / Q000378:metabolism*; D017510:Protein Folding; D055314:Seed Storage Proteins / Q000378:metabolism*
chemical_list: D055314:Seed Storage Proteins; D010088:Oxidoreductases; D019704:Protein Disulfide-Isomerases