7ld0
From Proteopedia
Cryo-EM structure of ligand-free Human SARM1
Structural highlights
Function[SARM1_HUMAN] Negative regulator of MYD88- and TRIF-dependent toll-like receptor signaling pathway which plays a pivotal role in activating axonal degeneration following injury. Promotes Wallerian degeneration an injury-induced axonal death pathway which involves degeneration of an axon distal to the injury site. Can activate neuronal death in response to stress. Regulates dendritic arborization through the MAPK4-JNK pathway. Involved in innate immune response. Inhibits both TICAM1/TRIF- and MYD88-dependent activation of JUN/AP-1, TRIF-dependent activation of NF-kappa-B and IRF3, and the phosphorylation of MAPK14/p38.[1] [2] [3] [4] Publication Abstract from PubMedAxon degeneration is a central pathological feature of many neurodegenerative diseases. Sterile alpha and Toll/interleukin-1 receptor motif-containing 1 (SARM1) is a nicotinamide adenine dinucleotide (NAD(+))-cleaving enzyme whose activation triggers axon destruction. Loss of the biosynthetic enzyme NMNAT2, which converts nicotinamide mononucleotide (NMN) to NAD(+), activates SARM1 via an unknown mechanism. Using structural, biochemical, biophysical, and cellular assays, we demonstrate that SARM1 is activated by an increase in the ratio of NMN to NAD(+) and show that both metabolites compete for binding to the auto-inhibitory N-terminal armadillo repeat (ARM) domain of SARM1. We report structures of the SARM1 ARM domain bound to NMN and of the homo-octameric SARM1 complex in the absence of ligands. We show that NMN influences the structure of SARM1 and demonstrate via mutagenesis that NMN binding is required for injury-induced SARM1 activation and axon destruction. Hence, SARM1 is a metabolic sensor responding to an increased NMN/NAD(+) ratio by cleaving residual NAD(+), thereby inducing feedforward metabolic catastrophe and axonal demise. SARM1 is a metabolic sensor activated by an increased NMN/NAD(+) ratio to trigger axon degeneration.,Figley MD, Gu W, Nanson JD, Shi Y, Sasaki Y, Cunnea K, Malde AK, Jia X, Luo Z, Saikot FK, Mosaiab T, Masic V, Holt S, Hartley-Tassell L, McGuinness HY, Manik MK, Bosanac T, Landsberg MJ, Kerry PS, Mobli M, Hughes RO, Milbrandt J, Kobe B, DiAntonio A, Ve T Neuron. 2021 Mar 1. pii: S0896-6273(21)00083-0. doi:, 10.1016/j.neuron.2021.02.009. PMID:33657413[5] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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Categories: Human | Large Structures | Gu, W | Jia, X | Kobe, B | Landsberg, M J | Luo, Z | Nanson, J D | Ve, T | Allostery | Autoinhibition | Hydrolase | Nad | Nadase | Neurodegeneration | Signaling protein | Toxin
