| Title | A Comprehensive Mutational Analysis of the Arabidopsis Resistance Protein RPW8.2 Reveals Key Amino Acids for Defense Activation and Protein Targeting. |
| Publication Type | Journal Article |
| Year of Publication | 2013 |
| Authors | Wang, W, Zhang, Y, Wen, Y, Berkey, R, Ma, X, Pan, Z, Bendigeri, D, King, H, Zhang, Q, Xiao, S |
| Journal | Plant Cell |
| Date Published | 2013 Oct 22 |
| ISSN | 1532-298X |
| Abstract | <p>The Arabidopsis thaliana RESISTANCE TO POWDERY MILDEW8.2 (RPW8.2) protein is specifically targeted to the extrahaustorial membrane (EHM) encasing the haustorium, or fungal feeding structure, where RPW8.2 activates broad-spectrum resistance against powdery mildew pathogens. How RPW8.2 activates defenses at a precise subcellular locale is not known. Here, we report a comprehensive mutational analysis in which more than 100 RPW8.2 mutants were functionally evaluated for their defense and trafficking properties. We show that three amino acid residues (i.e., threonine-64, valine-68, and aspartic acid-112) are critical for RPW8.2-mediated cell death and resistance to powdery mildew (Golovinomyces cichoracearum UCSC1). Also, we reveal that two arginine (R)- or lysine (K)-enriched short motifs (i.e., R/K-R/K-x-R/K) make up the likely core EHM-targeting signals, which, together with the N-terminal transmembrane domain, define a minimal sequence of 60 amino acids that is necessary and sufficient for EHM localization. In addition, some RPW8.2 mutants localize to the nucleus and/or to a potentially novel membrane that wraps around plastids or plastid-derived stromules. Results from this study not only reveal critical amino acid elements in RPW8.2 that enable haustorium-targeted trafficking and defense, but also provide evidence for the existence of a specific, EHM-oriented membrane trafficking pathway in leaf epidermal cells invaded by powdery mildew.</p> |
| DOI | 10.1105/tpc.113.117226 |
| Alternate Journal | Plant Cell |
| PubMed ID | 24151293 |
