{"doi":"10.1016/j.jbc.2022.102019","title":"Analysis of functional surfaces on the actin nucleation promoting factor Dip1 required for Arp2/3 complex activation and endocytic actin network assembly","abstract":"Arp2/3 complex nucleates branched actin filaments that drive processes like endocytosis and lamellipodial protrusion. WISH/DIP/SPIN90 (WDS) proteins form a class of Arp2/3 complex activators or nucleation promoting factors (NPFs) that, unlike WASP family NPFs, activate Arp2/3 complex without requiring preformed actin filaments. Therefore, activation of Arp2/3 complex by WDS proteins is thought to produce the initial actin filaments that seed branching nucleation by WASP-bound Arp2/3 complexes. However, whether activation of Arp2/3 complex by WDS proteins is important for the initiation of branched actin assembly in cells has not been directly tested. Here, we used structure-based point mutations of the Schizosaccharomyces pombe WDS protein Dip1 to test the importance of its Arp2/3-activating activity in cells. Six of thirteen Dip1 mutants caused severe defects in Arp2/3 complex activation in vitro, and we found a strong correlation between the ability of mutants to activate Arp2/3 complex and to rescue endocytic actin assembly defects caused by deleting Dip1. These data support a model in which Dip1 activates Arp2/3 complex to produce actin filaments that initiate branched actin assembly at endocytic sites. Dip1 mutants that synergized with WASP in activating Arp2/3 complex in vitro showed milder defects in cells compared to those that did not, suggesting that in cells the two NPFs may coactivate Arp2/3 complex to initiate actin assembly. Finally, the mutational data reveal important complementary electrostatic contacts at the Dip1-Arp2/3 complex interface and corroborate the previously proposed wedge model, which describes how Dip1 binding triggers structural changes that activate Arp2/3 complex.","journal":"Journal of Biological Chemistry","year":2022,"id":277712,"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":7,"citer_count":0,"citers_with_citation_signal":0,"citers_with_endowment":0,"datacite_reuse_total":0,"is_dataset":false,"is_dataset_confidence":0.9595,"is_data_producer":false,"deposit_databanks":null,"is_oa":true,"file_count":0,"downloads":0,"has_version_chain":false,"published_date":"2022-01-01","fair_score":null,"fair_percentile":null,"algorithm_id":"datarank_citation_only_1hop_v6","ranking_scope":"data_only","authors":[{"id":856463,"name":"Heidy Y. Narvaez‐Ortiz","orcid":"0000-0002-6434-6292","position":1,"is_corresponding":false},{"id":949775,"name":"Matt Miner","orcid":null,"position":2,"is_corresponding":false},{"id":949776,"name":"Jack Kiemel","orcid":null,"position":3,"is_corresponding":false},{"id":949777,"name":"Nicholas J. Oberhelman","orcid":null,"position":4,"is_corresponding":false},{"id":949325,"name":"April C. Watt","orcid":"0000-0002-5145-5334","position":5,"is_corresponding":false},{"id":688197,"name":"Andrew R. Wagner","orcid":"0000-0002-1833-766X","position":6,"is_corresponding":false},{"id":949326,"name":"Qing Luan","orcid":"0009-0002-2437-4499","position":7,"is_corresponding":false},{"id":493983,"name":"Luke A. Helgeson","orcid":"0000-0001-5112-2751","position":8,"is_corresponding":false},{"id":314360,"name":"Brad J. Nolen","orcid":"0000-0002-0224-9980","position":9,"is_corresponding":false},{"id":949324,"name":"Suling Liu","orcid":"0000-0002-0475-0242","position":0,"is_corresponding":true}],"reference_count":53,"raw_metadata":null,"created_at":"2026-07-19T00:28:39.226969Z","pmid":"35533728","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":[]}