Multiple Domain Associations within the Arabidopsis Immune Receptor RPP1 Regulate the Activation of Programmed Cell Death
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Date
2016
Authors
Schreiber, K
Bentham, Adam
Williams, S
Kobe, B
Staskawicz, B
Journal Title
Journal ISSN
Volume Title
Publisher
Public Library of Science
Rights
Copyright © 2016 Schreiber et al
Rights Holder
The Authors
Abstract
Upon recognition of pathogen virulence effectors, plant nucleotide-binding leucine-rich
repeat (NLR) proteins induce defense responses including localized host cell death. In an
effort to understand the molecular mechanisms leading to this response, we examined the
Arabidopsis thaliana NLR protein RECOGNITION OF PERONOSPORA PARASITICA1
(RPP1), which recognizes the Hyaloperonospora arabidopsidis effector ARABIDOPSIS
THALIANA RECOGNIZED1 (ATR1). Expression of the N-terminus of RPP1, including the
Toll/interleukin-1 receptor (TIR) domain (“N-TIR”), elicited an effector-independent cell
death response, and we used allelic variation in TIR domain sequences to define the key
residues that contribute to this phenotype. Further biochemical characterization indicated
that cell death induction was correlated with N-TIR domain self-association. In addition,
we demonstrated that the nucleotide-binding (NB)-ARC1 region of RPP1 self-associates
and plays a critical role in cell death activation, likely by facilitating TIR:TIR interactions.
Structural homology modeling of the NB subdomain allowed us to identify a putative oligomerization
interface that was shown to influence NB-ARC1 self-association. Significantly,
full-length RPP1 exhibited effector-dependent oligomerization and, although mutations at
the NB-ARC1 oligomerization interface eliminated cell death induction, RPP1 self-association
was unaffected, suggesting that additional regions contribute to oligomerization.
Indeed, the leucine-rich repeat domain of RPP1 also self-associates, indicating that multiple
interaction interfaces exist within activated RPP1 oligomers. Finally, we observed numerous
intramolecular interactions that likely function to negatively regulate RPP1, and present
a model describing the transition to an active NLR protein.
Description
This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
Keywords
Citation
Schreiber KJ, Bentham A, Williams SJ, Kobe B, Staskawicz BJ. Multiple Domain Associations within the Arabidopsis Immune Receptor RPP1 Regulate the Activation of Programmed Cell Death. Dangl JL, ed. PLoS Pathogens. 2016;12(7):e1005769. doi:10.1371/journal.ppat.1005769.