Molecular and spatial constraints on NB-LRR receptor signaling

In plants, a large polymorphic family of intracellular NB-LRR receptors lies at the heart of robust resistance to diverse pathogens and mechanisms by which these versatile molecular switches operate in effector-triggered immunity are beginning to emerge. We outline recent advances in our understanding of NB-LRR receptor signaling leading to disease resistance. Themes covered are (i) NB-LRR molecular constraining forces and their intimate relationship with receptor activation in different parts of the cell, (ii) cooperativity between NB-LRR proteins and the formation of higher order NB-LRR signaling complexes, and (iii) the spatial separation of different resistance branches within cells. Finally, we examine evidence for dynamic signaling across cell compartments in coordinating diverse immune outputs.

► NB-LRRs become activated via co-factors releasing them from an auto-inhibited state.
► Receptor self-association is emerging as an important feature of NB-LRR resistance function.
► There are many different sites of NB-LRR activation and some NB-LRRs signal inside nuclei.
► Certain NB-LRR types signal downstream of effector recognition.
► There is coordination of qualitatively different immune outputs across cell compartments.