Download MendeleyStructure-function analysis of ceTIR-1/hSARM1 explains the lack of Wallerian axonal degeneration in C. elegans.
Khazma, T., Grossman, A., Guez-Haddad, J., Feng, C., Dabas, H., Sain, R., Weitman, M., Zalk, R., Isupov, M.N., Hammarlund, M., Hons, M., Opatowsky, Y.(2023) Cell Rep 42: 113026-113026
- PubMed: 37635352
- DOI: https://doi.org/10.1016/j.celrep.2023.113026
- Primary Citation of Related Structures:
8P2L, 8P2M - PubMed Abstract:
Wallerian axonal degeneration (WD) does not occur in the nematode C. elegans, in contrast to other model animals. However, WD depends on the NADase activity of SARM1, a protein that is also expressed in C. elegans (ceSARM/ceTIR-1). We hypothesized that differences in SARM between species might exist and account for the divergence in WD. We first show that expression of the human (h)SARM1, but not ceTIR-1, in C. elegans neurons is sufficient to confer axon degeneration after nerve injury. Next, we determined the cryoelectron microscopy structure of ceTIR-1 and found that, unlike hSARM1, which exists as an auto-inhibited ring octamer, ceTIR-1 forms a readily active 9-mer. Enzymatically, the NADase activity of ceTIR-1 is substantially weaker (10-fold higher Km) than that of hSARM1, and even when fully active, it falls short of consuming all cellular NAD + . Our experiments provide insight into the molecular mechanisms and evolution of SARM orthologs and WD across species.
Organizational Affiliation:
The Mina & Everard Goodman Faculty of Life Sciences, Bar-Ilan University, Ramat-Gan, Israel.
