title: Multiple roles of the ER stress sensor IRE1 demonstrated by gene targeting in rice.
abstract: The endoplasmic reticulum (ER) stress sensor, IRE1, contains a kinase domain and a ribonuclease domain. Ribonuclease mediates the unconventional splicing of mRNA encoding the transcription factor AtbZIP60 in Arabidopsis, or OsbZIP50 in rice, and thereby transduces signals from stressed ER. Here, we demonstrate the additional roles of plant IRE1 using genetically modified rice plants. Using a gene targeting system based on homologous recombination, genomic IRE1 was replaced with two types of missense alleles, leading to a defect in the kinase or ribonuclease activity of IRE1. Genetic analysis of these alleles demonstrated that the kinase activity of IRE1 plays a vital role independent of ribonuclease activity. Furthermore, the existence of ribonuclease substrates other than OsbZIP50 mRNA is demonstrated for the first time. This study provides new insights into higher plant signalling using a gene targeting approach.
authors.affiliation: Genetically Modified Organism Research Center, National Institute of Agrobiological Sciences , Kannondai 2-1-2, Tsukuba, Ibaraki 305-8602, Japan.
authors.forename: Yuhya
authors.initials: Y
authors.lastname: Wakasa
authors.forename: Shimpei
authors.initials: S
authors.lastname: Hayashi
authors.forename: Kenjirou
authors.initials: K
authors.lastname: Ozawa
authors.forename: Fumio
authors.initials: F
authors.lastname: Takaiwa
mesh_terms: D000483:Alleles; D000595:Amino Acid Sequence; D059865:Endoplasmic Reticulum Stress; D020125:Mutation, Missense; D012275:Oryza / Q000235:genetics / Q000378:metabolism*; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism*; D030821:Plants, Genetically Modified / Q000254:growth & development; D012333:RNA, Messenger / Q000378:metabolism
chemical_list: D010940:Plant Proteins; D012333:RNA, Messenger