Oligomerisation of a plant helper NLR requires cell-surface and intracellular immune receptor activation

Abstract

Plant disease resistance involves both detection of microbial molecular patterns by cell-surface pattern recognition receptors and detection of pathogen effectors by intracellular NLR immune receptors. NLRs are classified as sensor NLRs, involved in effector detection, or helper NLRs required for sensor NLR signalling. TIR-domain-containing sensor NLRs (TNLs) require helper NLRs NRG1 and ADR1 for resistance, and their activation of defense also requires the lipase-domain proteins EDS1, SAG101 and PAD4. We investigated how the helper NLR NRG1 supports TNL-initiated immunity with EDS1 and SAG101. We find that NRG1 associates with EDS1 and SAG101 at the plasma membrane and in the nucleus, but only self-associates at the plasma membrane. Activation of TNLs is sufficient to trigger NRG1-EDS1-SAG101 interaction, but cell-surface receptor-initiated defense is also required to form an oligomeric Resistosome. The data point to formation of NRG1-EDS1-SAG101 heterotrimers in the nucleus upon intracellular receptor activation alone and indicate formation of NRG1-EDS1-SAG101 Resistosomes at the plasma membrane upon co-activation of intracellular and cell surface-receptor pathways.

Effector‐dependent activation and oligomerization of plant NRC class helper NLRs by sensor NLR immune receptors Rpi‐amr3 and Rpi‐amr1

“…This method was used to identify composition of mitochondrial membrane protein complexes and photosynthetic protein complexes in plants (Eubel et al , 2005 ). Recently, this method has been widely used to reveal oligomeric changes of NLRs in plants (Li et al , 2019 ; Hu et al , 2020 ; Na Ayutthaya et al , 2020 ; Jacob et al , 2021 ; preprint: Feehan et al , 2022 ). We used the blue native‐PAGE method to investigate not only protein–protein interactions, but also the approximate size of protein complexes in vivo .…”

“…The oligomerization of ZAR1 and Sr35 into a pentamer upon effector detection induces assembly of oligomers of the N‐terminal α‐helix in the CC domain to form a cation channel in the plasma membrane that is required for signaling (Wang et al , 2019a ; Bi et al , 2021 ; Förderer et al , 2022 ; Zhao et al , 2022 ). The CC R ‐NLR NRG1.1 and ADR1 also oligomerize and localize to the plasma membrane and can mediate calcium ion influx (Jacob et al , 2021 , preprint: Feehan et al , 2022 ). However, whether all NLRs form resistosomes upon activation is unclear.…”

EDS1 complexes are not required for PRR responses and execute TNL‐ETI from the nucleus in Nicotiana benthamiana

“…In the case of At ADR1, counteracting plasma membrane localization by depletion of phosphatidylinositol‐4‐phosphate impaired ADR1‐mediated cell death induction, further supporting membrane‐associated functions of ADR1 in immunity (Saile et al ., 2021). Recently, also nuclear localization and functions of Arabidopsis NRG1 were proposed (Feehan et al ., 2022), and appear not to be linked to NRG1 resistosome formation (Feehan et al ., 2022). It is of major interest for future analyses to determine how and in which compartment EDS1‐RNL interactions (Qi et al ., 2018; Sun et al ., 2021; Wu et al ., 2021) mediate RNL activation and TNL immunity.…”

Plasma membrane association and resistosome formation of plant helper immune receptors

“…We present data that ETI activated via the effector XopQ and the TNL Roq1 induces the RNL AtNRG1.1 oligomerization and puncta formation at the PM (Figure 4). A recent study showed that oligomerization of AtNRG1.2 requires not only effector-mediated activation of a TNL but also activation of PTI (51). Our data show that the cytoplasmic pool of AtEDS1/AtSAG101 mediates the cell death response, but are not present in the oligomerized AtNRG1.1 resistosome (Figure 5A and 5B).…”