title: GLYCINE-RICH RNA-BINDING PROTEIN1 interacts with RECEPTOR-LIKE CYTOPLASMIC PROTEIN KINASE1 and suppresses cell death and defense responses in pepper (Capsicum annuum).
abstract: Plants use a variety of innate immune regulators to trigger cell death and defense responses against pathogen attack. We identified pepper (Capsicum annuum) GLYCINE-RICH RNA-BINDING PROTEIN1 (CaGRP1) as a RECEPTOR-LIKE CYTOPLASMIC PROTEIN KINASE1 (CaPIK1)-interacting partner, based on bimolecular fluorescence complementation and coimmunoprecipitation analyses as well as gene silencing and transient expression analysis. CaGRP1 contains an N-terminal RNA recognition motif and a glycine-rich region at the C-terminus. The CaGRP1 protein had DNA- and RNA-binding activity in vitro. CaGRP1 interacted with CaPIK1 in planta. CaGRP1 and CaGRP1-CaPIK1 complexes were localized to the nucleus in plant cells. CaPIK1 phosphorylated CaGRP1 in vitro and in planta. Transient coexpression of CaGRP1 with CaPIK1 suppressed the CaPIK1-triggered cell death response, accompanied by a reduced CaPIK1-triggered reactive oxygen species (ROS) burst. The RNA recognition motif region of CaGRP1 was responsible for the nuclear localization of CaGRP1 as well as the suppression of the CaPIK1-triggered cell death response. CaGRP1 silencing in pepper conferred enhanced resistance to Xanthomonas campestris pv vesicatoria (Xcv) infection; however, CaPIK1-silenced plants were more susceptible to Xcv. CaGRP1 interacts with CaPIK1 and negatively regulates CaPIK1-triggered cell death and defense responses by suppressing ROS accumulation.
authors.affiliation: Laboratory of Molecular Plant Pathology, College of Life Sciences and Biotechnology, Korea University, Anam-dong, Sungbuk-ku, Seoul, 136-713, Korea.
authors.forename: Dae Sung
authors.initials: DS
authors.lastname: Kim
authors.forename: Nak Hyun
authors.initials: NH
authors.lastname: Kim
authors.forename: Byung Kook
authors.initials: BK
authors.lastname: Hwang
mesh_terms: D002212:Capsicum / Q000166:cytology / Q000378:metabolism* / Q000382:microbiology; D016923:Cell Death / Q000235:genetics; D018506:Gene Expression Regulation, Plant; D020868:Gene Silencing; D054884:Host-Pathogen Interactions; D010766:Phosphorylation; D010935:Plant Diseases / Q000382:microbiology; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism*; D030821:Plants, Genetically Modified; D016601:RNA-Binding Proteins / Q000235:genetics / Q000378:metabolism; D017382:Reactive Oxygen Species / Q000378:metabolism; D016959:Xanthomonas campestris / Q000472:pathogenicity
chemical_list: D010940:Plant Proteins; D016601:RNA-Binding Proteins; D017382:Reactive Oxygen Species; C100791:glycine-rich RNA-binding protein, plant
keywords: DNA and RNA binding; Xanthomonas campestris pv vesicatoria (Xcv); cell death; glycine-rich RNA-binding protein; pepper (Capsicum annuum); plant defense; receptor-like cytoplasmic protein kinase