{"doi":"10.1101/2021.06.20.449175","title":"A hemifused complex is the hub in a network of pathways to membrane fusion","abstract":"Abstract Membrane fusion is a critical step for many essential processes, from neurotransmission to fertilization. For over 40 years protein-free fusion driven by calcium or other cationic species has provided a simplified model of biological fusion, but the mechanisms remain poorly understood. Cation-mediated membrane fusion and permeation are essential in their own right to drug delivery strategies based on cell-penetrating peptides or cation-bearing lipid nanoparticles. Experimental studies suggest calcium drives anionic membranes to a hemifused intermediate which constitutes a hub in a network of pathways, but the pathway selection mechanism is unknown. Here we develop a mathematical model that identifies the network hub as a highly dynamical hemifusion complex. Multivalent cations drive expansion of this high tension hemifusion interface between interacting vesicles during a brief transient. The fate of this interface determines the outcome, either fusion, dead-end hemifusion or vesicle lysis. The model reproduces the unexplained finding that calcium-driven fusion of vesicles with planar membranes typically stalls at hemifusion, and we show the equilibrated hemifused state is a novel lens-shaped complex. Thus, membrane fusion kinetics follow a stochastic trajectory within a network of pathways, with outcome weightings set by a hemifused complex intermediate. Significance Cells use multicomponent machineries to fuse membranes for neurotransmitter and hormone release and other fundamental processes. Protein-free fusion using calcium or other multivalent cationic fusogens has long been studied as a simplifying model. Cation-mediated membrane fusion or permeation are key events for a number of current drug delivery strategies. However, the mechanisms determining outcomes are unknown. Here we develop a mathematical model that identifies a dynamic hemifusion complex as the decision hub that stochastically sets the outcome in a network of pathways. Cations transiently grow a high tension hemifusion interface between membrane-enclosed compartments, whose fate governs whether fusion, dead-end hemifusion or vesicle lysis occurs. The model provides a systematic framework to predict outcomes of cationic fusogen-mediated interactions between membrane-enclosed compartments.","journal":"bioRxiv (Cold Spring Harbor Laboratory)","year":2021,"id":225548,"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":0.9541,"is_data_producer":false,"deposit_databanks":null,"is_oa":true,"file_count":0,"downloads":0,"has_version_chain":false,"published_date":"2021-01-01","fair_score":null,"fair_percentile":null,"algorithm_id":"datarank_citation_only_1hop_v6","ranking_scope":"data_only","authors":[{"id":582633,"name":"Dong An","orcid":"0000-0002-2506-0486","position":1,"is_corresponding":false},{"id":828317,"name":"Benjamin S. Stratton","orcid":null,"position":2,"is_corresponding":false},{"id":344699,"name":"Ben O’Shaughnessy","orcid":"0000-0003-4223-3489","position":3,"is_corresponding":false},{"id":827975,"name":"Jason Warner","orcid":"0000-0003-4675-3385","position":0,"is_corresponding":true}],"reference_count":63,"raw_metadata":{"citation_network_status":"fetched"},"created_at":"2026-07-18T23:54:26.581453Z","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":[]}