Poster
Hee-Kyung Ahn
Royal Society University Research Fellow
University of Edinburgh
EDINBURGH, Scotland, United Kingdom
Guanghao Guo
State Key Laboratory of Plant Cell and Chromosome Engineering, Chinese Academy of Sciences
Beijing, Beijing, China (People's Republic)
Shania Keh
The Sainsbury Laboratory
Norwich, England, United Kingdom
Sung Un Huh
Kunsan National University
Gunsan, Cholla-bukto, Republic of Korea
Jan Sklenar
The Sainsbury Laboratory
Norwich, England, United Kingdom
Michelle T. Hulin
Michigan State University
East Lansing, Michigan, United States
Hayden Burdett
Wellcome Centre for Cell Biology, University of Edinburgh
Edinburgh, Scotland, United Kingdom
Lena Knorr
The Sainsbury Laboratory
Norwich, England, United Kingdom
He Zhao
The Sainsbury Laboratory
NORWICH, UNITED KINGDOM
Nitika Mukhi
Max Planck Institute for Plant Breeding Research
Cologne, Nordrhein-Westfalen, Germany
Maria Sindalovskaya
Postgraduate researcher
John Innes Centre
Norwich, England, United Kingdom
Mark J. Banfield
Group Leader
John Innes Centre
Norwich, England, United Kingdom
Frank L.H. Menke
The Sainsbury Laboratory
Norwich, England, United Kingdom
Wenbo Ma (she/her/hers)
The Sainsbury Laboratory
Norwich, UNITED KINGDOM
Jonathan D. G. Jones
Prof. Group leader
The Sainsbury Laboratory
Norwich, England, United Kingdom
The Arabidopsis paired TIR-NLR immune receptors RRS1 and RPS4 function together to enable recognition of bacterial effector proteins AvrRps4 and PopP2. Association of TIR domains activate NADase activity, and NAD+ is cleaved into small molecules such as ADPr-ATP, pRib-AMP (Li, Manik et al. Curr Opin Microbiol 74:102316). We show here that RRS1 and RPS4 form an oligomer that does not change in size upon effector provision, although NADase activity can be detected in the presence of its cognate effector PopP2. Oligomer formation involves interactions between the RRS1 and RPS4 TIR domains and requires the P-loop motif of RPS4. A cysteine residue in the LRR domain of RPS4 is also essential for oligomerization of the RRS1/RPS4 complex. Loss of oligomerization is correlated with loss of effector recognition revealed by lack of HR in N. tabacum infiltrations in these cases. However, RPS4 mutants that lose TIR domain NADase activity abrogate immune activation but retain oligomerization. Alphafold3 prediction of RRS1 and RPS4 TIR domains show a high probability of heterotetramer formation in the absence of activation, without NAD+. We propose that upon effector recognition, conformational changes in the complex relieve inhibition of RPS4 TIR domains by RRS1 TIR domains, enabling RPS4 TIR domains to create NADase activity.