Journal Article

Isolation and Characterization of a Putative Transducer of Endoplasmic Reticulum Stress in <i>Oryza sativa</i>

Yoko Okushima, Nozomu Koizumi, Yube Yamaguchi, Yukio Kimata, Kenji Kohno and Hiroshi Sano

in Plant and Cell Physiology

Published on behalf of Japanese Society of Plant Physiologists

Volume 43, issue 5, pages 532-539
Published in print May 2002 | ISSN: 0032-0781
Published online May 2002 | e-ISSN: 1471-9053 | DOI: http://dx.doi.org/10.1093/pcp/pcf063
Isolation and Characterization of a Putative Transducer of Endoplasmic Reticulum Stress in Oryza sativa

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  • Biochemistry
  • Molecular and Cell Biology
  • Plant Sciences and Forestry

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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.

Keywords: Key words: Chaperone — Endoplasmic reticulum — Oryza sativa — Unfolded protein response.; Abbreviations: CBB, Coomassie brilliant blue; C-terminal, carboxyl-terminal; DTT, dithiothreitol; ER, endoplasmic reticulum; EST, expression sequence tag; GFP, green fluorescent protein; GST, glutathione S-transferase; N-linked, asparagine-linked; N-terminal, amino-terminal; SD, synthetic dextrose; UPR, unfolded protein response.

Journal Article.  5067 words.  Illustrated.

Subjects: Biochemistry ; Molecular and Cell Biology ; Plant Sciences and Forestry

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