Bottom-up reconstruction of functional death fold signalosomes reveals a requirement for polymer stability and avidity

Protein polymer scaffolds composed of death fold (DF) proteins are critical to the formation of signalosomes in immune signaling. The biophysical properties that these polymeric scaffolds require for signal transduction are not clearly defined. Here, we engineered single-component DF signalosomes. We found that functionality depends on the stability provided by the DF polymer, which could also be achieved with a bacterial DF domain, a synthetic filament-forming domain, and amyloid-like sequences. This demonstrates the importance of polymer stability and inducibility irrespective of the motif's origin. By varying the number of included TRAF6 interaction motifs, we demonstrate that avidity is a tunable property that can control the amplitude of signaling outputs. This work lays out a reductionist framework to elucidate the required signaling properties through polymeric scaffolds by adjusting their assembly kinetics, stability, and avidity.