Isolation and characterization of a putative transducer of endoplasmic reticulum stress in Oryza sativa.
Following endoplasmic reticulum (ER) stress that prevents correct folding or assembly of ER proteins, at least three responses occur to maintain cell homeostasis: induction of chaperones, attenuation of protein synthesis, and enhancement of lipid synthesis. Transducers that transmit ER stress to the nucleus have already been identified in yeast and mammals. We report here isolation of a cDNA, OsIre1, from rice encoding a putative homolog of Ire1p, a yeast transducer of ER stress. OsIre1 encodes a polypeptide consisting of 893 amino acids, in which two hydrophobic stretches are present in the amino-terminal (N-terminal) and middle regions, possibly serving as a signal peptide and a transmembrane domain, respectively. The carboxyl-terminal (C-terminal) domain was found to possess serine/threonine protein kinase and ribonuclease-like domains showing high similarities with regions in Ire1 homologs from other organisms. A fusion protein of OsIre1 and green fluorescent protein (GFP) expressed in tobacco BY2 cells could be demonstrated to localize to the ER and the N-terminal domain of OsIre1 could substitute for yeast Ire1p in yeast cells. When produced in bacteria as a fusion protein, the C-terminal region of OsIre1 showed autophosphorylation activity. These results thus indicate that OsIre1 encodes a putative plant transducer of ER stress.
Okushima
Yoko
Y
Research and Education Center for Genetic Information, Nara Institute of Science and Technology, Ikoma 630-0101 Japan.
Koizumi
Nozomu
N
Yamaguchi
Yube
Y
Kimata
Yukio
Y
Kohno
Kenji
K
Sano
Hiroshi
H
D000595:Amino Acid Sequence; D002460:Cell Line; D018076:DNA, Complementary / Q000737:chemistry / Q000235:genetics / Q000302:isolation & purification; D004721:Endoplasmic Reticulum / Q000378:metabolism*; D018506:Gene Expression Regulation, Plant; D005982:Glutathione Transferase / Q000235:genetics / Q000378:metabolism; D049452:Green Fluorescent Proteins; D008055:Lipids / Q000096:biosynthesis; D008164:Luminescent Proteins / Q000235:genetics / Q000378:metabolism; D018832:Molecular Chaperones / Q000378:metabolism; D008969:Molecular Sequence Data; D012275:Oryza / Q000235:genetics* / Q000378:metabolism; D010455:Peptides / Q000235:genetics* / Q000378:metabolism; D010766:Phosphorylation; D010770:Phosphotransferases / Q000378:metabolism; D010940:Plant Proteins / Q000235:genetics* / Q000378:metabolism; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000235:genetics; D016415:Sequence Alignment; D017422:Sequence Analysis, DNA; D017386:Sequence Homology, Amino Acid; D015398:Signal Transduction; D014026:Nicotiana / Q000166:cytology
D018076:DNA, Complementary; D008055:Lipids; D008164:Luminescent Proteins; D018832:Molecular Chaperones; D010455:Peptides; D010940:Plant Proteins; D011993:Recombinant Fusion Proteins; D049452:Green Fluorescent Proteins; D005982:Glutathione Transferase; D010770:Phosphotransferases