{"doi":"10.1101/2024.05.08.593111","title":"Structure of the human CTF18–RFC clamp loader bound to PCNA","abstract":"Sliding clamps like PCNA are crucial processivity factors for replicative polymerases, requiring specific clamp loaders for loading onto DNA. The human alternative clamp loader CTF18-RFC interacts with the leading strand polymerase Pol ε and loads PCNA onto primer/template DNA using its RFC pentameric module. Here, we provide a structural characterization of the human CTF18-RFC complex and its interaction with PCNA. Our cryo-EM data support that the Ctf8 and Dcc1 subunits of CTF18-RFC, which form the regulatory module interacting with Pol ε, are flexibly tethered to the RFC module. A 2.9 Å cryo-EM structure shows the RFC module bound to PCNA in an autoinhibited conformation similar to the canonical RFC loader, marking the initial step of the clamp-loading reaction. The unique RFC1 (Ctf18) large subunit of CTF18-RFC, which based on the cryo-EM map shows high relative flexibility, is anchored to PCNA through an atypical low-affinity PIP box in the AAA+ domain and engages the RFC5 subunit using a novel β-hairpin at the disordered N-terminus. We show that deletion of this β-hairpin impairs the CTF18-RFC-PCNA complex stability, slows down clamp loading, and decreases the rate of primer synthesis by Pol ε. Our research identifies distinctive structural characteristics of the human CTF18-RFC complex, providing insights into its role in PCNA loading and the stimulation of leading strand synthesis by Pol ε.","journal":"bioRxiv (Cold Spring Harbor Laboratory)","year":2024,"id":490901,"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":1,"citer_count":0,"citers_with_citation_signal":0,"citers_with_endowment":0,"datacite_reuse_total":0,"is_dataset":false,"is_dataset_confidence":0.9529,"is_data_producer":false,"deposit_databanks":null,"is_oa":true,"file_count":0,"downloads":0,"has_version_chain":false,"published_date":"2024-01-01","fair_score":null,"fair_percentile":null,"algorithm_id":"datarank_citation_only_1hop_v6","ranking_scope":"data_only","authors":[{"id":901567,"name":"Muhammad Tehseen","orcid":"0000-0001-9834-2372","position":1,"is_corresponding":false},{"id":1336672,"name":"Amani Al-Amodi","orcid":null,"position":2,"is_corresponding":false},{"id":545713,"name":"Grace Young","orcid":"0000-0002-5210-1183","position":3,"is_corresponding":false},{"id":913455,"name":"Ammar Usman Danazumi","orcid":"0000-0003-3763-056X","position":4,"is_corresponding":false},{"id":1336673,"name":"Phong Quoc Nguyen","orcid":null,"position":5,"is_corresponding":false},{"id":262069,"name":"Christos G. Savva","orcid":"0000-0003-3354-6483","position":6,"is_corresponding":false},{"id":415429,"name":"Mark Hedglin","orcid":"0000-0003-2599-1691","position":7,"is_corresponding":false},{"id":736231,"name":"Samir M. Hamdan","orcid":"0000-0001-5192-1852","position":8,"is_corresponding":false},{"id":1336371,"name":"Alfredo De Biasio","orcid":"0000-0003-2139-2958","position":9,"is_corresponding":false},{"id":1336370,"name":"Giuseppina R. Briola","orcid":"0009-0001-8771-6743","position":0,"is_corresponding":true}],"reference_count":68,"raw_metadata":null,"created_at":"2026-07-19T02:08:41.211111Z","pmid":"40777363","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":[]}