title: An OsCEBiP/OsCERK1-OsRacGEF1-OsRac1 module is an essential early component of chitin-induced rice immunity.
abstract: OsCEBiP, a chitin-binding protein, and OsCERK1, a receptor-like kinase, are plasma membrane (PM) proteins that form a receptor complex essential for fungal chitin-driven immune responses in rice. The signaling events immediately following chitin perception are unclear. Investigating the spatiotemporal regulation of the rice small GTPase OsRac1, we find that chitin induces rapid activation of OsRac1 at the PM. Searching for OsRac1 interactors, we identified OsRacGEF1 as a guanine nucleotide exchange factor for OsRac1. OsRacGEF1 interacts with OsCERK1 and is activated when its C-terminal S549 is phosphorylated by the cytoplasmic domain of OsCERK1 in response to chitin. Activated OsRacGEF1 is required for chitin-driven immune responses and resistance to rice blast fungus infection. Further, a protein complex including OsCERK1 and OsRacGEF1 is transported from the endoplasmic reticulum to the PM. Collectively, our results suggest that OsCEBiP, OsCERK1, OsRacGEF1, and OsRac1 function as key components of a "defensome" critically engaged early during chitin-induced immunity.
authors.affiliation: Laboratory of Plant Molecular Genetics, Graduate School of Biological Sciences, Nara Institute of Science and Technology, 8916-5 Takayama, Ikoma, Nara 630-0192, Japan.
authors.forename: Akira
authors.initials: A
authors.lastname: Akamatsu
authors.forename: Hann Lin
authors.initials: HL
authors.lastname: Wong
authors.forename: Masayuki
authors.initials: M
authors.lastname: Fujiwara
authors.forename: Jun
authors.initials: J
authors.lastname: Okuda
authors.forename: Keita
authors.initials: K
authors.lastname: Nishide
authors.forename: Kazumi
authors.initials: K
authors.lastname: Uno
authors.forename: Keiko
authors.initials: K
authors.lastname: Imai
authors.forename: Kenji
authors.initials: K
authors.lastname: Umemura
authors.forename: Tsutomu
authors.initials: T
authors.lastname: Kawasaki
authors.forename: Yoji
authors.initials: Y
authors.lastname: Kawano
authors.forename: Ko
authors.initials: K
authors.lastname: Shimamoto
mesh_terms: D000595:Amino Acid Sequence; D002686:Chitin / Q000276:immunology* / Q000378:metabolism*; D003593:Cytoplasm / Q000276:immunology / Q000378:metabolism / Q000382:microbiology; D004721:Endoplasmic Reticulum / Q000276:immunology / Q000378:metabolism / Q000382:microbiology; D005658:Fungi / Q000276:immunology; D020662:Guanine Nucleotide Exchange Factors / Q000276:immunology / Q000378:metabolism; D008565:Membrane Proteins / Q000276:immunology / Q000378:metabolism; D008969:Molecular Sequence Data; D020559:Monomeric GTP-Binding Proteins / Q000276:immunology / Q000378:metabolism; D012275:Oryza / Q000276:immunology* / Q000378:metabolism / Q000382:microbiology*; D010766:Phosphorylation; D010935:Plant Diseases / Q000276:immunology* / Q000382:microbiology; D010940:Plant Proteins / Q000276:immunology* / Q000378:metabolism*; D051192:Receptors, Pattern Recognition / Q000276:immunology / Q000378:metabolism; D015398:Signal Transduction
chemical_list: D020662:Guanine Nucleotide Exchange Factors; D008565:Membrane Proteins; D010940:Plant Proteins; D051192:Receptors, Pattern Recognition; D002686:Chitin; D020559:Monomeric GTP-Binding Proteins