RRC ID 12617
Author Takemoto Y, Coughlan SJ, Okita TW, Satoh H, Ogawa M, Kumamaru T.
Title The rice mutant esp2 greatly accumulates the glutelin precursor and deletes the protein disulfide isomerase.
Journal Plant Physiol.
Abstract Rice (Oryza sativa) accumulates prolamins and glutelins as storage proteins. The latter storage protein is synthesized on the endoplasmic reticulum (ER) as a 57-kD proglutelin precursor, which is then processed into acidic and basic subunits in the protein storage vacuole. Three esp2 mutants, CM1787, EM44, and EM747, contain larger amounts of the 57-kD polypeptide and corresponding lower levels of acidic and basic glutelin subunits than normal. Electron microscopic observation revealed that esp2 contained normal-appearing glutelin-containing protein bodies (PB-II), but lacked the normal prolamin-containing PB (PB-I). Instead, numerous small ER-derived PBs of uniform size (0.5 microm in diameter) and low electron density were readily observed. Immunoblot analysis of purified subcellular fractions and immunocytochemistry at the electron microscopy level showed that these new PBs contained the 57-kD proglutelin precursor and prolamin polypeptides. The 57-kD proglutelin was extracted with 1% (v/v) lactic acid solution only after removal of cysteine-rich prolamin polypeptides, suggesting that these proteins form glutelin-prolamin aggregates via interchain disulfide bonds within the ER lumen. The endosperm of esp2 mutants contains the lumenal chaperones, binding protein and calnexin, but lacks protein disulfide isomerase (PDI) at the protein and RNA levels. The transcript of PDI was expressed in the seed only during the early stage of seed development in the wild type. These results suggest that PDI plays an essential role in the segregation of proglutelin and prolamin polypeptides within the ER lumen.
Volume 128(4)
Pages 1212-22
Published 2002-4
DOI 10.1104/pp.010624
PMID 11950970
PMC PMC154249
MeSH Blotting, Northern Blotting, Western Cysteine / metabolism Endoplasmic Reticulum / metabolism Gene Deletion Glutens / metabolism* Immunohistochemistry Microscopy, Electron Microscopy, Fluorescence Mutation Oryza / genetics Oryza / metabolism* Plant Proteins / metabolism Prolamins Protein Disulfide-Isomerases / genetics* Protein Disulfide-Isomerases / metabolism Protein Precursors / metabolism RNA, Plant / genetics RNA, Plant / metabolism Seeds / enzymology Seeds / growth & development Seeds / ultrastructure
IF 6.305
Times Cited 105
Rice Induced Mutation Lines