title: Vacuolar processing enzyme plays an essential role in the crystalline structure of glutelin in rice seed.
abstract: To identify the function of genes that regulate the processing of proglutelin, we performed an analysis of glup3 mutants, which accumulates excess amounts of proglutelin and lack the vacuolar processing enzyme (VPE). VPE activity in developing seeds from glup3 lines was reduced remarkably compared with the wild type. DNA sequencing of the VPE gene in glup3 mutants revealed either amino acid substitutions or the appearance of a stop codon within the coding region. Microscopic observations showed that alpha-globulin and proglutelin were distributed homogeneously within glup3 protein storage vacuoles (PSVs), and that glup3 PSVs lacked the crystalline lattice structure typical of wild-type PSVs. This suggests that the processing of proglutelin by VPE in rice is essential for proper PSV structure and compartmentalization of storage proteins. Growth retardation in glup3 seedlings was also observed, indicating that the processing of proglutelin influences early seedling development. These findings indicate that storage of glutelin in its mature form as a crystalline structure in PSVs is required for the rapid use of glutelin as a source of amino acids during early seedling development. In conclusion, VPE plays an important role in the formation of protein crystalline structures in PSVs.
authors.affiliation: Faculty of Agriculture, Kyushu University, Fukuoka, Japan. kumamaru@agr.kyushu-u.ac.jp
authors.forename: Toshihiro
authors.initials: T
authors.lastname: Kumamaru
authors.forename: Yuji
authors.initials: Y
authors.lastname: Uemura
authors.forename: Yoshimi
authors.initials: Y
authors.lastname: Inoue
authors.forename: Yoko
authors.initials: Y
authors.lastname: Takemoto
authors.forename: Sadar Uddin
authors.initials: SU
authors.lastname: Siddiqui
authors.forename: Masahiro
authors.initials: M
authors.lastname: Ogawa
authors.forename: Ikuko
authors.initials: I
authors.lastname: Hara-Nishimura
authors.forename: Hikaru
authors.initials: H
authors.lastname: Satoh
mesh_terms: D000596:Amino Acids / Q000378:metabolism; D001483:Base Sequence; D018388:Codon, Terminator / Q000235:genetics; D003460:Crystallization; D018360:Crystallography, X-Ray; D003546:Cysteine Endopeptidases / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D005455:Fluorescent Antibody Technique; D018506:Gene Expression Regulation, Plant / Q000235:genetics; D017343:Genes, Plant / Q000235:genetics; D005983:Glutens / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D046529:Microscopy, Electron, Transmission; D008969:Molecular Sequence Data; D009154:Mutation / Q000235:genetics; D012275:Oryza / Q000201:enzymology* / Q000254:growth & development / Q000648:ultrastructure; D017433:Protein Structure, Secondary / Q000235:genetics; D012639:Seeds / Q000201:enzymology* / Q000254:growth & development / Q000648:ultrastructure; D014617:Vacuoles / Q000201:enzymology* / Q000648:ultrastructure
chemical_list: D000596:Amino Acids; D018388:Codon, Terminator; D005983:Glutens; D003546:Cysteine Endopeptidases; C089278:vacuolar processing enzyme