Dataset Information

A conserved motif is essential for the correct assembly of proglutelins and for their export from the endoplasmic reticulum in rice endosperm.

ABSTRACT: Rice glutelins are initially synthesized as 57-kDa precursors at the endoplasmic reticulum (ER) and are ultimately transported into protein storage vacuoles. However, the sequence motifs that affect proglutelin folding, assembly, and their export from the ER remain poorly defined. In this study, we characterized a mutant with nine amino acids deleted in the GluA2 protein, which resulted in specific accumulation of the GluA precursor. The deleted amino acids constitute a well-conserved sequence (LVYIIQGRG) in glutelins and all residues in this motif are necessary for ER export of GluA2. Immunoelectron microscopy and stable transgenic analyses indicated that proglutelins with deletion of this motif misassembled and aggregated through non-native intermolecular disulfide bonds, and were deposited in ER-derived protein bodies (PB-Is), resulting in conversion of PB-Is into a new type of PB. These results indicate that the conserved motif is essential for proper assembly of proglutelin. The correct assembly of proglutelins is critical for their segregation from prolamins in the ER lumen, which is essential for enabling the export of proglutelin from the ER and for the proper formation of PB-Is. We also found that the interchain disulfide bond between acidic and basic subunits is not necessary for their assembly, but it is required for proglutelin folding.

SUBMITTER: Tian L

PROVIDER: S-EPMC6184509 | biostudies-literature | 2018 Oct

REPOSITORIES: biostudies-literature

ACCESS DATA

Publications

A conserved motif is essential for the correct assembly of proglutelins and for their export from the endoplasmic reticulum in rice endosperm.

Tian Lihong L Xing Yanping Y Fukuda Masako M Li Rong R Kumamaru Toshihiro T Qian Dandan D Dong Xiangbai X Qu Le Qing LQ

Journal of experimental botany 20181001 21

Rice glutelins are initially synthesized as 57-kDa precursors at the endoplasmic reticulum (ER) and are ultimately transported into protein storage vacuoles. However, the sequence motifs that affect proglutelin folding, assembly, and their export from the ER remain poorly defined. In this study, we characterized a mutant with nine amino acids deleted in the GluA2 protein, which resulted in specific accumulation of the GluA precursor. The deleted amino acids constitute a well-conserved sequence ( ...[more]

PMID: 30107432

Similar Datasets

Project description:Glycosylphosphatidylinositol (GPI)-anchored proteins are cell surface-localized proteins that serve many important cellular functions. The pathway mediating synthesis and attachment of the GPI anchor to these proteins in eukaryotic cells is complex, highly conserved, and plays a critical role in the proper targeting, transport, and function of all GPI-anchored protein family members. In this article, we demonstrate that MCD4, an essential gene that was initially identified in a genetic screen to isolate Saccharomyces cerevisiae mutants defective for bud emergence, encodes a previously unidentified component of the GPI anchor synthesis pathway. Mcd4p is a multimembrane-spanning protein that localizes to the endoplasmic reticulum (ER) and contains a large NH2-terminal ER lumenal domain. We have also cloned the human MCD4 gene and found that Mcd4p is both highly conserved throughout eukaryotes and has two yeast homologues. Mcd4p's lumenal domain contains three conserved motifs found in mammalian phosphodiesterases and nucleotide pyrophosphases; notably, the temperature-conditional MCD4 allele used for our studies (mcd4-174) harbors a single amino acid change in motif 2. The mcd4-174 mutant (1) is defective in ER-to-Golgi transport of GPI-anchored proteins (i.e., Gas1p) while other proteins (i.e., CPY) are unaffected; (2) secretes and releases (potentially up-regulated cell wall) proteins into the medium, suggesting a defect in cell wall integrity; and (3) exhibits marked morphological defects, most notably the accumulation of distorted, ER- and vesicle-like membranes. mcd4-174 cells synthesize all classes of inositolphosphoceramides, indicating that the GPI protein transport block is not due to deficient ceramide synthesis. However, mcd4-174 cells have a severe defect in incorporation of [3H]inositol into proteins and accumulate several previously uncharacterized [3H]inositol-labeled lipids whose properties are consistent with their being GPI precursors. Together, these studies demonstrate that MCD4 encodes a new, conserved component of the GPI anchor synthesis pathway and highlight the intimate connections between GPI anchoring, bud emergence, cell wall function, and feedback mechanisms likely to be involved in regulating each of these essential processes. A putative role for Mcd4p as participating in the modification of GPI anchors with side chain phosphoethanolamine is also discussed.

Dataset Information

A conserved motif is essential for the correct assembly of proglutelins and for their export from the endoplasmic reticulum in rice endosperm.

Publications

A conserved motif is essential for the correct assembly of proglutelins and for their export from the endoplasmic reticulum in rice endosperm.

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure

Tweets