Ligand-triggered allosteric ADP release primes a plant NLR complex

The plant resistosome comes into focus Nucleotide-binding, leucine-rich repeat receptors (NLRs) initiate immune responses when they sense a pathogen-associated effector. In animals, oligomerization of NLRs upon binding their effectors is key to downstream activity, but plant systems differ in many ways and their activation mechanisms have been less clear. In two papers, Wang et al. studied the composition and structure of an NLR called ZAR1 in the small mustard plant Arabidopsis (see the Perspective by Dangl and Jones). They determined cryo–electron microscopy structures that illustrate differences between inactive and intermediate states. The active, intermediate state of ZAR1 forms a wheel-like pentamer, called the resistosome. In this activated complex, a set of helices come together to form a funnel-shaped structure required for immune responsiveness and association with the plasma membrane. Science , this issue p. eaav5868 , p. eaav5870 ; see also p. 31