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- Title
Comprehensive Mutational Analysis of the Arabidopsis Resistance Protein RPW8.2 Reveals Key Amino Acids for Defense Activation and Protein Targeting.
- Authors
Wang, Wenming; Zhang, Yi; Wen, Yingqiang; Berkey, Robert; Ma, Xianfeng; Pan, Zhiyong; Bendigeri, Dipti; King, Harlan; Zhang, Qiong; Xiao, Shunyuan
- Abstract
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-116) 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.
- Subjects
ARABIDOPSIS proteins; TRANSMEMBRANE domains; AMINO acid sequence; POWDERY mildew diseases; AMINO acid residues; AMINO acids
- Publication
Plant Cell, 2013, Vol 25, Issue 10, p4242
- ISSN
1040-4651
- Publication type
Article
- DOI
10.1105/tpc.113.117226