An activated wheat CC_G10-NLR immune receptor forms an octameric resistosome

Area of Science:

• Plant immunity
• Molecular biology
• Structural biology

Background:

• Nucleotide-binding, leucine-rich repeat (NLR) receptors are crucial intracellular immune sensors.
• Plant G10-type coiled-coil (CCG10)-NLRs represent a distinct, poorly understood subgroup.
• Wheat autoimmunity 3 (WAI3) is a CCG10-NLR involved in plant defense.

Purpose of the Study:

• To characterize the structure and function of the wheat CCG10-NLR, WAI3.
• To investigate the oligomeric state and assembly of activated CCG10-NLRs.
• To explore the conserved structural properties of CCG10-NLRs in plants.

Main Methods:

• Identification and characterization of a gain-of-function mutant (WAI3GOF).
• Cryo-electron microscopy (cryo-EM) to determine the structure of activated WAI3.
• Analysis of cytosolic calcium levels in response to WAI3 activation.

Main Results:

• Activated WAI3 forms a distinct octameric resistosome structure.
• Arabidopsis RPS2, another CCG10-NLR, also forms an octamer, indicating conservation.
• The WAI3 resistosome induces sustained cytosolic calcium increase, suggesting a novel ion channel function.
• Divergent CC domain configuration in WAI3 may relate to NLRs lacking the EDVID motif.

Conclusions:

• A conserved octameric resistosome structure is characteristic of plant CCG10-NLRs.
• WAI3's structure provides insights into plant immune receptor plasticity and function.
• The findings reveal a previously uncharacterized NLR resistosome assembly and its role in calcium signaling.