title: The pepper E3 ubiquitin ligase RING1 gene, CaRING1, is required for cell death and the salicylic acid-dependent defense response.
abstract: Ubiquitination is essential for ubiquitin/proteasome-mediated protein degradation in plant development and defense. Here, we identified a novel E3 ubiquitin ligase RING1 gene, CaRING1, from pepper (Capsicum annuum). In pepper, CaRING1 expression is induced by avirulent Xanthomonas campestris pv vesicatoria infection. CaRING1 contains an amino-terminal transmembrane domain and a carboxyl-terminal RING domain. In addition, it displays in vitro E3 ubiquitin ligase activity, and the RING domain is essential for E3 ubiquitin ligase activity in CaRING1. CaRING1 also localizes to the plasma membrane. In pepper plants, virus-induced gene silencing of CaRING1 confers enhanced susceptibility to avirulent X. campestris pv vesicatoria infection, which is accompanied by compromised hypersensitive cell death, reduced expression of PATHOGENESIS-RELATED1, and lowered salicylic acid levels in leaves. Transient expression of CaRING1 in pepper leaves induces cell death and the defense response that requires the E3 ubiquitin ligase activity of CaRING1. By contrast, overexpression of CaRING1 in Arabidopsis (Arabidopsis thaliana) confers enhanced resistance to hemibiotrophic Pseudomonas syringae pv tomato and biotrophic Hyaloperonospora arabidopsidis infections. Taken together, these results suggest that CaRING1 is involved in the induction of cell death and the regulation of ubiquitination during the defense response to microbial pathogens.
authors.affiliation: Laboratory of Molecular Plant Pathology, School of Life Sciences and Biotechnology, Korea University, Seoul 136-713, Republic of Korea.
authors.forename: Dong Hyuk
authors.initials: DH
authors.lastname: Lee
authors.forename: Hyong Woo
authors.initials: HW
authors.lastname: Choi
authors.forename: Byung Kook
authors.initials: BK
authors.lastname: Hwang
mesh_terms: D000595:Amino Acid Sequence; D017360:Arabidopsis / Q000235:genetics / Q000276:immunology / Q000382:microbiology; D002212:Capsicum / Q000166:cytology* / Q000201:enzymology / Q000235:genetics / Q000276:immunology*; D016923:Cell Death / Q000187:drug effects / Q000235:genetics; D002462:Cell Membrane / Q000187:drug effects / Q000201:enzymology; D017124:Conserved Sequence / Q000235:genetics; D060467:Disease Resistance / Q000187:drug effects / Q000235:genetics; D018506:Gene Expression Regulation, Plant / Q000187:drug effects; D017343:Genes, Plant / Q000235:genetics*; D008969:Molecular Sequence Data; D010935:Plant Diseases / Q000235:genetics / Q000276:immunology / Q000382:microbiology; D018515:Plant Leaves / Q000187:drug effects / Q000235:genetics / Q000382:microbiology; D010940:Plant Proteins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D030821:Plants, Genetically Modified; D017434:Protein Structure, Tertiary; D021381:Protein Transport / Q000187:drug effects; D020156:Salicylic Acid / Q000494:pharmacology*; D013347:Subcellular Fractions / Q000187:drug effects / Q000201:enzymology; D044767:Ubiquitin-Protein Ligases / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D014774:Virulence / Q000187:drug effects / Q000235:genetics; D016959:Xanthomonas campestris / Q000187:drug effects / Q000472:pathogenicity
chemical_list: D010940:Plant Proteins; D044767:Ubiquitin-Protein Ligases; D020156:Salicylic Acid