A conformation-specific nanobody targeting the nicotinamide mononucleotide-activated state of SARM1.
basic_science · Level V
Where this comes from
- Record sourced from PubMed, PMID 36550129.
- Also identified by DOI 10.1038/s41467-022-35581-y and PMC identifier 9780360.
- Licence recorded as CC BY.
- The licence permits redistribution, so the abstract is shown in full and the full text is available from the publisher.
Abstract
Sterile alpha (SAM) and Toll/interleukin-1 receptor (TIR) motif containing 1 (SARM1) is an autoinhibitory NAD-consuming enzyme that is activated by the accumulation of nicotinamide mononucleotide (NMN) during axonal injury. Its activation mechanism is not fully understood. Here, we generate a nanobody, Nb-C6, that specifically recognizes NMN-activated SARM1. Nb-C6 stains only the activated SARM1 in cells stimulated with CZ-48, a permeant mimetic of NMN, and partially activates SARM1 in vitro and in cells. Cryo-EM of NMN/SARM1/Nb-C6 complex shows an octameric structure with ARM domains bending significantly inward and swinging out together with TIR domains. Nb-C6 binds to SAM domain of the activated SARM1 and stabilized its ARM domain. Mass spectrometry analyses indicate that the activated SARM1 in solution is highly dynamic and that the neighboring TIRs form transient dimers via the surface close to one BB loop. We show that Nb-C6 is a valuable tool for studies of SARM1 activation.
Medical subject headings
- Nicotinamide Mononucleotide
- Axons