The CC domain structure from the wheat stem rust resistance protein Sr33 challenges paradigms for dimerization in plant NLR proteins

Casey, Lachlan W., Lavrencic, Peter, Bentham, Adam R., Cesari, Stella, Ericsson, Daniel J., Croll, Tristan, Turk, Dušan, Anderson, Peter A., Mark, Alan E., Dodds, Peter N., Mobli, Mehdi, Kobe, Bostjan and Williams, Simon J. (2016) The CC domain structure from the wheat stem rust resistance protein Sr33 challenges paradigms for dimerization in plant NLR proteins. Proceedings of the National Academy of Sciences, 113 45: 12856-12861. doi:10.1073/pnas.1609922113


Author Casey, Lachlan W.
Lavrencic, Peter
Bentham, Adam R.
Cesari, Stella
Ericsson, Daniel J.
Croll, Tristan
Turk, Dušan
Anderson, Peter A.
Mark, Alan E.
Dodds, Peter N.
Mobli, Mehdi
Kobe, Bostjan
Williams, Simon J.
Title The CC domain structure from the wheat stem rust resistance protein Sr33 challenges paradigms for dimerization in plant NLR proteins
Journal name Proceedings of the National Academy of Sciences   Check publisher's open access policy
ISSN 1091-6490
0027-8424
Publication date 2016-11-08
Sub-type Article (original research)
DOI 10.1073/pnas.1609922113
Open Access Status Not yet assessed
Volume 113
Issue 45
Start page 12856
End page 12861
Total pages 6
Place of publication Washington, DC, United States
Publisher National Academy of Sciences
Language eng
Formatted abstract
Plants use intracellular immunity receptors, known as nucleotidebinding oligomerization domain-like receptors (NLRs), to recognize specific pathogen effector proteins and induce immune responses. These proteins provide resistance to many of the world’s most destructive plant pathogens, yet we have a limited understanding of the molecular mechanisms that lead to defense signaling. We examined the wheat NLR protein, Sr33, which is responsible for strainspecific resistance to the wheat stem rust pathogen, Puccinia graminis f. sp. tritici. We present the solution structure of a coiled-coil (CC) fragment from Sr33, which adopts a four-helix bundle conformation. Unexpectedly, this structure differs from the published dimeric crystal structure of the equivalent region from the orthologous barley powdery mildew resistance protein, MLA10, but is similar to the structure of the distantly related potato NLR protein, Rx. We demonstrate that these regions are, in fact, largely monomeric and adopt similar folds in solution in all three proteins, suggesting that the CC domains from plant NLRs adopt a conserved fold. However, larger C-terminal fragments of Sr33 and MLA10 can self-associate both in vitro and in planta, and this self-association correlates with their cell death signaling activity. The minimal region of the CC domain required for both cell death signaling and self-association extends to amino acid 142, thus including 22 residues absent from previous biochemical and structural protein studies. These data suggest that self-association of the minimal CC domain is necessary for signaling but is likely to involve a different structural basis than previously suggested by the MLA10 crystallographic dimer.
Keyword Plant innate immunity
Resistance protein
NLR proteins
Effector-triggered immunity
Nuclear magnetic resonance spectroscopy
Q-Index Code C1
Q-Index Status Provisional Code
Institutional Status UQ

 
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Created: Fri, 18 Nov 2016, 22:01:27 EST by Mrs Louise Nimwegen on behalf of School of Chemistry & Molecular Biosciences