Axon degeneration is an active program of self-destruction mediated by the protein SARM1. In healthy neurons, SARM1 is autoinhibited and, upon injury autoinhibition is relieved, activating the SARM1 enzyme to deplete NAD+ and induce axon degeneration. SARM1 forms a homomultimeric octamer with each monomer composed of an N-terminal autoinhibitory ARM domain, tandem SAM domains that mediate multimerization, and a C-terminal TIR domain encoding the NADase enzyme. Here we discovered multiple intramolecular and intermolecular domain interfaces required for SARM1 autoinhibition using peptide mapping and cryo-electron microscopy (cryo-EM). We identified a candidate autoinhibitory region by screening a panel of peptides derived from the SARM1 ARM domain, identifying a peptide mediating high-affinity inhibition of the SARM1 NADase. Mutation of residues in full-length SARM1 within the region encompassed by the peptide led to loss of autoinhibition, rendering SARM1 constitutively active and inducing spontaneous NAD+ and axon loss. The cryo-EM structure of SARM1 revealed 1) a compact autoinhibited SARM1 octamer in which the TIR domains are isolated and prevented from oligomerization and enzymatic activation and 2) multiple candidate autoinhibitory interfaces among the domains. Mutational analysis demonstrated that five distinct interfaces are required for autoinhibition, including intramolecular and intermolecular ARM-SAM interfaces, an intermolecular ARM-ARM interface, and two ARM-TIR interfaces formed between a single TIR and two distinct ARM domains. These autoinhibitory regions are not redundant, as point mutants in each led to constitutively active SARM1. These studies define the structural basis for SARM1 autoinhibition and may enable the development of SARM1 inhibitors that stabilize the autoinhibited state.Glucose-6-phosphate dehydrogenase (G6PD) deficiency is the most common blood disorder, presenting multiple symptoms, including hemolytic anemia. It affects 400 million people worldwide, with more than 160 single mutations reported in G6PD. The most severe mutations (about 70) are classified as class I, leading to more than 90% loss of activity of the wild-type G6PD. The crystal structure of G6PD reveals these mutations are located away from the active site, concentrating around the noncatalytic NADP+-binding site and the dimer interface. However, the molecular mechanisms of class I mutant dysfunction have remained elusive, hindering the development of efficient therapies. To resolve this, we performed integral structural characterization of five G6PD mutants, including four class I mutants, associated with the noncatalytic NADP+ and dimerization, using crystallography, small-angle X-ray scattering (SAXS), cryogenic electron microscopy (cryo-EM), and biophysical analyses. Comparisons with the structure and properties of the wild-type enzyme, together with molecular dynamics simulations, bring forward a universal mechanism for this severe G6PD deficiency due to the class I mutations. We highlight the role of the noncatalytic NADP+-binding site that is crucial for stabilization and ordering two β-strands in the dimer interface, which together communicate these distant structural aberrations to the active site through a network of additional interactions. This understanding elucidates potential paths for drug development targeting G6PD deficiency.Recent technological advances have expanded the annotated protein coding content of mammalian genomes, as hundreds of previously unidentified, short open reading frame (ORF)-encoded peptides (SEPs) have now been found to be translated. Although several studies have identified important physiological roles for this emerging protein class, a general method to define their interactomes is lacking. Here, we demonstrate that genetic incorporation of the photo-crosslinking noncanonical amino acid AbK into SEP transgenes allows for the facile identification of SEP cellular interaction partners using affinity-based methods. From a survey of seven SEPs, we report the discovery of short ORF-encoded histone binding protein (SEHBP), a conserved microprotein that interacts with chromatin-associated proteins, localizes to discrete genomic loci, and induces a robust transcriptional program when overexpressed in human cells. This work affords a straightforward method to help define the physiological roles of SEPs and demonstrates its utility by identifying SEHBP as a short ORF-encoded transcription factor.DNA damage repair genes are modifiers of disease onset in Huntington's disease (HD), but how this process intersects with associated disease pathways remains unclear. selleck inhibitor Here we evaluated the mechanistic contributions of protein inhibitor of activated STAT-1 (PIAS1) in HD mice and HD patient-derived induced pluripotent stem cells (iPSCs) and find a link between PIAS1 and DNA damage repair pathways. We show that PIAS1 is a component of the transcription-coupled repair complex, that includes the DNA damage end processing enzyme polynucleotide kinase-phosphatase (PNKP), and that PIAS1 is a SUMO E3 ligase for PNKP. Pias1 knockdown (KD) in HD mice had a normalizing effect on HD transcriptional dysregulation associated with synaptic function and disease-associated transcriptional coexpression modules enriched for DNA damage repair mechanisms as did reduction of PIAS1 in HD iPSC-derived neurons. KD also restored mutant HTT-perturbed enzymatic activity of PNKP and modulated genomic integrity of several transcriptionally normalized genes. The findings here now link SUMO modifying machinery to DNA damage repair responses and transcriptional modulation in neurodegenerative disease.The ability to cast a mail ballot can safeguard the franchise. However, because there are often additional procedural protections to ensure that a ballot cast in person counts, voting by mail can also jeopardize people's ability to cast a recorded vote. An experiment carried out during the COVID-19 pandemic illustrates both forces. Philadelphia officials randomly sent 46,960 Philadelphia registrants postcards encouraging them to apply to vote by mail in the lead-up to the June 2020 primary election. While the intervention increased the likelihood a registrant cast a mail ballot by 0.4 percentage points (P = 0.017)-or 3%-many of these additional mail ballots counted only because a last-minute policy intervention allowed most mail ballots postmarked by Election Day to count.selleck inhibitor