title: Identification of an essential component of the elicitation active site of the EIX protein elicitor.
abstract: Defense mechanisms of plants against pathogens often entail cell wall strengthening, ethylene biosynthesis, expression of pathogen-related proteins and hypersensitive responses (HR). Pathogen-derived elicitors trigger these defense responses. The Elicitor Ethylene-inducing Xylanase (EIX) elicits HR and other plant defense responses in some tobacco and tomato cultivars independently of its xylan degradation activity. The elicitation epitope on the EIX protein responsible for inducing the HR response has been elucidated. Through the generation of EIX-specific polyclonal antibodies and screening of combinatorial phage display peptide libraries an essential sequence of the EIX elicitation activity has been identified. This sequence consists of the pentapeptide TKLGE mapped to an exposed beta-strand of the EIX protein. Substitution of the pentapeptide TKLGE to VKGT inhibited the elicitation activity but not the beta-1-4-endoxylanase activity of the EIX protein further demonstrating that elicitation and enzyme activity are independent properties. Elucidation of a peptide sequence that is essential for elicitation of HR creates the opportunity to understand the control and signaling of plant defense.
authors.affiliation: Department of Plant Sciences, Faculty of Life Sciences Tel Aviv University, Ramat Aviv, Tel Aviv 69978, Israel.
authors.forename: Barak
authors.initials: B
authors.lastname: Rotblat
authors.forename: David
authors.initials: D
authors.lastname: Enshell-Seijffers
authors.forename: Jonathan M
authors.initials: JM
authors.lastname: Gershoni
authors.forename: Silvia
authors.initials: S
authors.lastname: Schuster
authors.forename: Adi
authors.initials: A
authors.lastname: Avni
mesh_terms: D000595:Amino Acid Sequence; D000906:Antibodies / Q000276:immunology / Q000378:metabolism; D001435:Bacteriophages / Q000235:genetics / Q000276:immunology; D001665:Binding Sites / Q000235:genetics; D001667:Binding, Competitive; D043364:Endo-1,4-beta Xylanases; D004790:Enzyme Induction; D018604:Epitope Mapping; D018506:Gene Expression Regulation, Plant; D007113:Immunity, Innate / Q000235:genetics; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D009154:Mutation; D010935:Plant Diseases / Q000235:genetics* / Q000821:virology; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism; D017386:Sequence Homology, Amino Acid; D015398:Signal Transduction / Q000235:genetics; D014026:Nicotiana / Q000235:genetics* / Q000821:virology; D014995:Xylosidases / Q000096:biosynthesis* / Q000235:genetics / Q000378:metabolism
chemical_list: D000906:Antibodies; D010940:Plant Proteins; D014995:Xylosidases; D043364:Endo-1,4-beta Xylanases