Comparative analysis of the flax immune receptors L6 and L7 suggests an equilibrium-based switch activation model

Bernoux, Maud, Burdett, Hayden, Williams, Simon J., Zhang, Xiaoxiao, Chen, Chunhong, Newell, Kim, Lawrence, Gregory J., Kobe, Bostjan, Ellis, Jeffrey G., Anderson, Peter A. and Dodds, Peter N. (2016) Comparative analysis of the flax immune receptors L6 and L7 suggests an equilibrium-based switch activation model. Plant Cell, 28 1: 146-159. doi:10.1105/tpc.15.00303


Author Bernoux, Maud
Burdett, Hayden
Williams, Simon J.
Zhang, Xiaoxiao
Chen, Chunhong
Newell, Kim
Lawrence, Gregory J.
Kobe, Bostjan
Ellis, Jeffrey G.
Anderson, Peter A.
Dodds, Peter N.
Title Comparative analysis of the flax immune receptors L6 and L7 suggests an equilibrium-based switch activation model
Journal name Plant Cell   Check publisher's open access policy
ISSN 1532-298X
1040-4651
Publication date 2016-01-01
Year available 2016
Sub-type Article (original research)
DOI 10.1105/tpc.15.00303
Open Access Status Not Open Access
Volume 28
Issue 1
Start page 146
End page 159
Total pages 14
Place of publication Rockville, MD United States
Publisher American Society of Plant Biologists
Collection year 2016
Language eng
Formatted abstract
NOD-like receptors (NLRs) are central components of the plant immune system. L6 is a Toll/interleukin-1 receptor (TIR) domain-containing NLR from flax (Linum usitatissimum) conferring immunity to the flax rust fungus. Comparison of L6 to the weaker allele L7 identified two polymorphic regions in the TIR and the nucleotide binding (NB) domains that regulate both effector ligand-dependent and -independent cell death signaling as well as nucleotide binding to the receptor. This suggests that a negative functional interaction between the TIR and NB domains holds L7 in an inactive/ADP-bound state more tightly than L6, hence decreasing its capacity to adopt the active/ATP-bound state and explaining its weaker activity in planta. L6 and L7 variants with a more stable ADP-bound state failed to bind to AvrL567 in yeast two-hybrid assays, while binding was detected to the signaling active variants. This contrasts with current models predicting that effectors bind to inactive receptors to trigger activation. Based on the correlation between nucleotide binding, effector interaction, and immune signaling properties of L6/L7 variants, we propose that NLRs exist in an equilibrium between ON and OFF states and that effector binding to the ON state stabilizes this conformation, thereby shifting the equilibrium toward the active form of the receptor to trigger defense signaling.
Q-Index Code C1
Q-Index Status Provisional Code
Institutional Status UQ

Document type: Journal Article
Sub-type: Article (original research)
Collections: HERDC Pre-Audit
School of Chemistry and Molecular Biosciences
Institute for Molecular Bioscience - Publications
 
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Created: Fri, 26 Feb 2016, 21:12:34 EST by Mrs Louise Nimwegen on behalf of School of Chemistry & Molecular Biosciences