title: N-terminal motifs in some plant disease resistance proteins function in membrane attachment and contribute to disease resistance.
abstract: To investigate the role of N-terminal domains of plant disease resistance proteins in membrane targeting, the N termini of a number of Arabidopsis and flax disease resistance proteins were fused to green fluorescent protein (GFP) and the fusion proteins localized in planta using confocal microscopy. The N termini of the Arabidopsis RPP1-WsB and RPS5 resistance proteins and the PBS1 protein, which is required for RPS5 resistance, targeted GFP to the plasma membrane, and mutation of predicted myristoylation and potential palmitoylation sites resulted in a shift to nucleocytosolic localization. The N-terminal domain of the membrane-attached Arabidopsis RPS2 resistance protein was targeted incompletely to the plasma membrane. In contrast, the N-terminal domains of the Arabidopsis RPP1-WsA and flax L6 and M resistance proteins, which carry predicted signal anchors, were targeted to the endomembrane system, RPP1-WsA to the endoplasmic reticulum and the Golgi apparatus, L6 to the Golgi apparatus, and M to the tonoplast. Full-length L6 was also targeted to the Golgi apparatus. Site-directed mutagenesis of six nonconserved amino acid residues in the signal anchor domains of L6 and M was used to change the localization of the L6 N-terminal fusion protein to that of M and vice versa, showing that these residues control the targeting specificity of the signal anchor. Replacement of the signal anchor domain of L6 by that of M did not affect L6 protein accumulation or resistance against flax rust expressing AvrL567 but removal of the signal anchor domain reduced L6 protein accumulation and L6 resistance, suggesting that membrane attachment is required to stabilize the L6 protein.
authors: Plant Science Division, Reearch School of Biology, The Australian National University, Canberra ACT 0200, Australia.
authors: Daigo
authors: D
authors: Takemoto
authors: Maryam
authors: M
authors: Rafiqi
authors: Ursula
authors: U
authors: Hurley
authors: Greg J
authors: GJ
authors: Lawrence
authors: Maud
authors: M
authors: Bernoux
authors: Adrienne R
authors: AR
authors: Hardham
authors: Jeffrey G
authors: JG
authors: Ellis
authors: Peter N
authors: PN
authors: Dodds
authors: David A
authors: DA
authors: Jones
mesh_terms: D020816:Amino Acid Motifs; D000595:Amino Acid Sequence; D019943:Amino Acid Substitution; D017360:Arabidopsis / Q000235:genetics / Q000378:metabolism*; D002462:Cell Membrane / Q000378:metabolism*; D060467:Disease Resistance; D004721:Endoplasmic Reticulum / Q000378:metabolism; D019597:Flax / Q000235:genetics / Q000378:metabolism*; D006056:Golgi Apparatus / Q000378:metabolism; D049452:Green Fluorescent Proteins; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D009154:Mutation; D010940:Plant Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D030821:Plants, Genetically Modified; D011993:Recombinant Fusion Proteins; D017386:Sequence Homology, Amino Acid
chemical_list: D010940:Plant Proteins; D011993:Recombinant Fusion Proteins; D049452:Green Fluorescent Proteins