{"doi":"10.1101/2020.07.01.181321","title":"The Sec1/Munc18 protein Vps45 holds the Qa-SNARE Tlg2 in an open conformation","abstract":"ABSTRACT Fusion of intracellular trafficking vesicles is mediated by the assembly of soluble N -ethylmaleimide-sensitive fusion protein receptors (SNAREs) to form membrane-bridging complexes. Also required for SNARE-mediated membrane fusion are Sec1/Munc18-family (SM) proteins, SNARE chaperones that can function as templates to catalyze SNARE complex assembly. In the paradigmatic structure of an SM–SNARE complex, Munc18-1 bound to the Qa-SNARE syntaxin 1, the SNARE protein is trapped in an autoinhibited closed conformation that prevents it from entering into SNARE complexes. Here, we present the structure of a second SM–Qa-SNARE complex, Vps45–Tlg2. Strikingly, Vps45 holds Tlg2 in an open conformation, with its SNARE motif disengaged from its three-helical Habc domain and its linker region unfolded. The domain 3a helical hairpin of Vps45 is unfurled, exposing the presumptive R-SNARE binding site to allow template complex formation. Tlg2 has a pronounced tendency to self-associate via its SNARE motif, and we demonstrate that Vps45 can rescue Tlg2 oligomers into stoichiometric Vps45–Tlg2 complexes. Our findings demonstrate that SM proteins can engage Qa-SNAREs using at least two different modes, one in which the SNARE is closed and one in which it is open.","journal":"bioRxiv (Cold Spring Harbor Laboratory)","year":2020,"id":130298,"datarank":0.0,"base_score":0.0,"endowment":0.0,"self_citation_contribution":0.0,"citation_network_contribution":0.0,"self_endowment_contribution":0.0,"citer_contribution":0.0,"corpus_percentile":null,"corpus_rank":null,"citation_count":0,"citer_count":0,"citers_with_citation_signal":0,"citers_with_endowment":0,"datacite_reuse_total":0,"is_dataset":false,"is_dataset_confidence":0.9581,"is_data_producer":false,"deposit_databanks":null,"is_oa":true,"file_count":0,"downloads":0,"has_version_chain":false,"published_date":"2020-01-01","fair_score":null,"fair_percentile":null,"algorithm_id":"datarank_citation_only_1hop_v6","ranking_scope":"data_only","authors":[{"id":472043,"name":"Frederick M. Allen","orcid":"0000-0002-2969-8137","position":1,"is_corresponding":false},{"id":472591,"name":"Kelly Lau","orcid":null,"position":2,"is_corresponding":false},{"id":472044,"name":"Gregory R. Shimamura","orcid":"0000-0003-2104-5518","position":3,"is_corresponding":false},{"id":259851,"name":"Philip D. Jeffrey","orcid":"0000-0002-4351-5341","position":4,"is_corresponding":false},{"id":259854,"name":"Frederick M. Hughson","orcid":"0000-0002-4057-0281","position":5,"is_corresponding":false},{"id":376058,"name":"Travis Eisemann","orcid":"0000-0003-3602-2677","position":0,"is_corresponding":true}],"reference_count":52,"raw_metadata":null,"created_at":"2026-07-18T23:15:53.196774Z","pmid":null,"pmcid":null,"fwci":null,"citation_percentile":null,"influential_citations":0,"oa_status":null,"license":null,"views":0,"total_file_size_bytes":0,"version_count":0,"fair_f":null,"fair_a":null,"fair_i":null,"fair_r":null,"fair_zscore":null,"fair_rationale":null,"fair_model":null,"fair_agent_version":null,"fair_fulltext_source":null,"fair_has_llm":null,"fair_computed_at":null,"clinical_trials":[],"software_tools":[],"db_accessions":[],"linked_datasets":[],"topics":[]}