The NAD + -mediated self-inhibition mechanism of pro-neurodegenerative SARM1.
Jiang, Y., Liu, T., Lee, C.H., Chang, Q., Yang, J., Zhang, Z.(2020) Nature 588: 658-663
- PubMed: 33053563 
- DOI: https://doi.org/10.1038/s41586-020-2862-z
- Primary Citation of Related Structures:  
7CM5, 7CM6, 7CM7 - PubMed Abstract: 
Pathological degeneration of axons disrupts neural circuits and represents one of the hallmarks of neurodegeneration 1-4 . Sterile alpha and Toll/interleukin-1 receptor motif-containing protein 1 (SARM1) is a central regulator of this neurodegenerative process 5-8 , and its Toll/interleukin-1 receptor (TIR) domain exerts its pro-neurodegenerative action through NADase activity 9,10 . However, the mechanisms by which the activation of SARM1 is stringently controlled are unclear. Here we report the cryo-electron microscopy structures of full-length SARM1 proteins. We show that NAD + is an unexpected ligand of the armadillo/heat repeat motifs (ARM) domain of SARM1. This binding of NAD + to the ARM domain facilitated the inhibition of the TIR-domain NADase through the domain interface. Disruption of the NAD + -binding site or the ARM-TIR interaction caused constitutive activation of SARM1 and thereby led to axonal degeneration. These findings suggest that NAD + mediates self-inhibition of this central pro-neurodegenerative protein.
Organizational Affiliation: 
State Key Laboratory of Membrane Biology, Center for Life Sciences, School of Life Sciences, Peking University, Beijing, China.