{"doi":"10.1107/s0907444999015334","title":"The molecular structure and structural transition of the α-helical capsid in filamentous bacteriophage Pf1","abstract":null,"journal":"Acta Crystallographica Section D Biological Crystallography","year":2000,"id":599914,"datarank":0.5495342469194471,"base_score":3.6635616461296463,"endowment":3.6635616461296463,"self_citation_contribution":0.5495342469194471,"citation_network_contribution":0.0,"self_endowment_contribution":0.5495342469194471,"citer_contribution":0.0,"corpus_percentile":null,"corpus_rank":null,"citation_count":38,"citer_count":0,"citers_with_citation_signal":0,"citers_with_endowment":0,"datacite_reuse_total":0,"is_dataset":false,"is_dataset_confidence":null,"is_data_producer":false,"deposit_databanks":null,"is_oa":false,"file_count":0,"downloads":0,"has_version_chain":false,"published_date":null,"fair_score":null,"fair_percentile":null,"algorithm_id":"datarank_citation_only_1hop_v6","ranking_scope":"data_only","authors":[{"id":74434,"name":"Martyn F. Symmons","orcid":null,"position":1,"is_corresponding":false},{"id":1537708,"name":"D. A. Marvin","orcid":null,"position":2,"is_corresponding":false},{"id":1537707,"name":"Liam C. Welsh","orcid":null,"position":0,"is_corresponding":false}],"reference_count":0,"raw_metadata":{"has_enrichment":true,"resolved":true,"title":"The molecular structure and structural transition of the α-helical capsid in filamentous bacteriophage Pf1","abstract":"The major coat protein in the capsid of Pf1 filamentous bacteriophage (Inovirus) forms a helical assembly of about 7000 identical protein subunits, each of which contains 46 amino-acid residues and can be closely approximated by a single gently curved alpha-helix. Since the viral DNA occupies the core of the tubular capsid and appears to make no significant specific interactions with the capsid proteins, the capsid is a simple model system for the study of the static and dynamic properties of alpha-helix assembly. The capsid undergoes a reversible temperature-induced structural transition at about 283 K between two slightly different helix forms. The two forms can coexist without an intermediate state, consistent with a first-order structural phase transition. The molecular model of the higher temperature form was refined using improved X-ray fibre diffraction data and new refinement and validation methods. The refinement indicates that the two forms are related by a change in the orientation of the capsid subunits within the virion, without a significant change in local conformation of the subunits. On the higher temperature diffraction pattern there is a region of observed intensity that is not consistent with a simple helix of identical subunits; it is proposed that the structure involves groups of three subunits which each have a slightly different orientation within the group. The grouping of subunits suggests that a change in subunit libration frequency could be the basis of the Pf1 structural transition; calculations from the model are used to explore this idea.","is_dataset_classified":null,"base_score":0.0,"endowment":0.0,"datacite_reuse_total":0,"file_count":0,"downloads":0,"views":0,"has_version_chain":false,"is_dataset":false,"is_oa":false,"pmid":"10666593","pmcid":null,"openalex_id":null,"authors":[],"funders":[],"total_grants":0,"fwci":null,"citation_percentile":null,"influential_citations":0,"citation_trend":[],"oa_status":"closed","license":"http://journals.iucr.org/services/copyrightpolicy.html","oa_locations":[{"url":"http://journals.iucr.org/d/issues/2000/02/00/ad0097/ad0097.pdf","host_type":"publisher"}],"fields_of_study":[],"mesh_terms":["Inovirus","Virion","Capsid","DNA, Viral","Crystallography, X-Ray","Temperature","Amino Acid Sequence","Protein Structure, Secondary","Thermodynamics","Models, Molecular","Molecular Sequence Data"],"keywords":[],"sdg_mappings":[],"linked_datasets":[],"clinical_trials":[],"software_tools":[],"database_accessions":[],"source":"live","citation_network_status":"fetched"},"created_at":"2026-07-29T11:40:59.618908Z","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":[]}