{"doi":"10.1111/tpj.14273","title":"Hetero‐oligomeric CPN60 resembles highly symmetric group‐I chaperonin structure revealed by Cryo‐EM","abstract":"<jats:title>Summary</jats:title>\n                  <jats:p>\n                    The chloroplast chaperonin system is indispensable for the biogenesis of Rubisco, the key enzyme in photosynthesis. Using\n                    <jats:italic>Chlamydomonas reinhardtii</jats:italic>\n                    as a model system, we found that\n                    <jats:italic>in vivo</jats:italic>\n                    the chloroplast chaperonin consists of CPN60α, CPN60β1 and CPN60β2 and the co‐chaperonin of the three subunits CPN20, CPN11 and CPN23. In\n                    <jats:italic>Escherichia coli,</jats:italic>\n                    CPN20 homo‐oligomers and all possible other chloroplast co‐chaperonin hetero‐oligomers are functional, but only that consisting of CPN11/20/23‐CPN60αβ1β2 can fully replace GroES/GroEL under stringent stress conditions. Endogenous CPN60 was purified and its stoichiometry was determined to be 6:2:6 for CPN60α:CPN60β1:CPN60β2. The cryo‐EM structures of endogenous CPN60αβ1β2/ADP and CPN60αβ1β2/co‐chaperonin/ADP were solved at resolutions of 4.06 and 3.82 Å, respectively. In both hetero‐oligomeric complexes the chaperonin subunits within each ring are highly symmetric. Through hetero‐oligomerization, the chloroplast co‐chaperonin CPN11/20/23 forms seven GroES‐like domains, which symmetrically interact with CPN60αβ1β2. Our structure also reveals an uneven distribution of roof‐forming domains in the dome‐shaped CPN11/20/23 co‐chaperonin and potentially diversified surface properties in the folding cavity of the CPN60αβ1β2 chaperonin that might enable the chloroplast chaperonin system to assist in the folding of specific substrates.\n                  </jats:p>","journal":"The Plant Journal","year":2019,"id":641787,"datarank":0.4636563680037475,"base_score":3.091042453358316,"endowment":3.091042453358316,"self_citation_contribution":0.4636563680037475,"citation_network_contribution":0.0,"self_endowment_contribution":0.4636563680037475,"citer_contribution":0.0,"corpus_percentile":null,"corpus_rank":null,"citation_count":21,"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":327184,"name":"Xiang Zhang","orcid":"0000-0003-1003-9892","position":1,"is_corresponding":false},{"id":1668892,"name":"Frederik Sommer","orcid":null,"position":2,"is_corresponding":false},{"id":1512707,"name":"Na Ta","orcid":null,"position":3,"is_corresponding":false},{"id":854220,"name":"Ning Wang","orcid":"0000-0003-1745-1425","position":4,"is_corresponding":false},{"id":280604,"name":"Michael Schroda","orcid":"0000-0001-6872-0483","position":5,"is_corresponding":false},{"id":38157,"name":"Yao Cong","orcid":"0000-0001-5602-2207","position":6,"is_corresponding":false},{"id":1668896,"name":"Cuimin Liu","orcid":null,"position":7,"is_corresponding":false},{"id":947179,"name":"Qian Zhao","orcid":"0000-0003-0304-8854","position":0,"is_corresponding":false}],"reference_count":0,"raw_metadata":{"has_enrichment":true,"resolved":true,"title":"Hetero‐oligomeric CPN60 resembles highly symmetric group‐I chaperonin structure revealed by Cryo‐EM","abstract":"<jats:title>Summary</jats:title>\n                  <jats:p>\n                    The chloroplast chaperonin system is indispensable for the biogenesis of Rubisco, the key enzyme in photosynthesis. Using\n                    <jats:italic>Chlamydomonas reinhardtii</jats:italic>\n                    as a model system, we found that\n                    <jats:italic>in vivo</jats:italic>\n                    the chloroplast chaperonin consists of CPN60α, CPN60β1 and CPN60β2 and the co‐chaperonin of the three subunits CPN20, CPN11 and CPN23. In\n                    <jats:italic>Escherichia coli,</jats:italic>\n                    CPN20 homo‐oligomers and all possible other chloroplast co‐chaperonin hetero‐oligomers are functional, but only that consisting of CPN11/20/23‐CPN60αβ1β2 can fully replace GroES/GroEL under stringent stress conditions. Endogenous CPN60 was purified and its stoichiometry was determined to be 6:2:6 for CPN60α:CPN60β1:CPN60β2. The cryo‐EM structures of endogenous CPN60αβ1β2/ADP and CPN60αβ1β2/co‐chaperonin/ADP were solved at resolutions of 4.06 and 3.82 Å, respectively. In both hetero‐oligomeric complexes the chaperonin subunits within each ring are highly symmetric. Through hetero‐oligomerization, the chloroplast co‐chaperonin CPN11/20/23 forms seven GroES‐like domains, which symmetrically interact with CPN60αβ1β2. Our structure also reveals an uneven distribution of roof‐forming domains in the dome‐shaped CPN11/20/23 co‐chaperonin and potentially diversified surface properties in the folding cavity of the CPN60αβ1β2 chaperonin that might enable the chloroplast chaperonin system to assist in the folding of specific substrates.\n                  </jats:p>","is_dataset_classified":null,"base_score":3.091042453358316,"endowment":3.091042453358316,"datacite_reuse_total":0,"file_count":0,"downloads":0,"views":0,"has_version_chain":false,"is_dataset":false,"is_oa":false,"pmid":"30735603","pmcid":null,"openalex_id":"https://openalex.org/W2949362552","authors":[],"funders":[{"funder_name":"National Natural Science Foundation of China","grant_id":"31671262","title":null},{"funder_name":"National Natural Science Foundation of China","grant_id":"31670754","title":null},{"funder_name":"Deutsche Forschungsgemeinschaft","grant_id":"TRR175","title":null},{"funder_name":"Deutsche Forschungsgemeinschaft","grant_id":"unidentified","title":"unidentified"}],"total_grants":4,"fwci":0.8351,"citation_percentile":0.71140577,"influential_citations":0,"citation_trend":[{"year":2020,"count":5},{"year":2021,"count":5},{"year":2022,"count":1},{"year":2023,"count":5},{"year":2024,"count":2},{"year":2025,"count":1},{"year":2026,"count":2}],"oa_status":"bronze","license":"Wiley Online Library User Agreement","oa_locations":[{"url":"https://onlinelibrary.wiley.com/doi/pdfdirect/10.1111/tpj.14273","host_type":"journal"},{"url":"https://onlinelibrary.wiley.com/doi/pdfdirect/10.1111/tpj.14273","host_type":"publisher"},{"url":"https://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1111%2Ftpj.14273","host_type":"publisher"},{"url":"https://onlinelibrary.wiley.com/doi/pdf/10.1111/tpj.14273","host_type":"publisher"},{"url":"https://onlinelibrary.wiley.com/doi/full-xml/10.1111/tpj.14273","host_type":"publisher"},{"url":"https://doi.org/10.1111/tpj.14273","host_type":"journal"},{"url":"https://pubmed.ncbi.nlm.nih.gov/30735603","host_type":"repository"},{"url":"https://doi.org/10.1101/432013","host_type":""},{"url":"https://dx.doi.org/10.1101/432013","host_type":""},{"url":"https://dx.doi.org/10.1111/tpj.14273","host_type":""},{"url":"http://dx.doi.org/10.1101/432013","host_type":""}],"fields_of_study":["Heat shock proteins research","Enzyme Structure and Function","Protein Structure and Dynamics","0301 basic medicine","0303 health sciences","03 medical and health sciences","Chaperonin 60","Chlamydomonas reinhardtii","Chloroplast Proteins","Chloroplasts","Cryoelectron Microscopy","Group I Chaperonins","Photosynthesis","Protein Folding","Protein Multimerization","Protein Subunits","Ribulose-Bisphosphate Carboxylase"],"mesh_terms":["Chloroplasts","Photosynthesis","Ribulose-Bisphosphate Carboxylase","Chlamydomonas reinhardtii","Protein Folding","Chaperonin 60","Cryoelectron Microscopy","Protein Subunits","Protein Multimerization","Group I Chaperonins","Chloroplast Proteins"],"keywords":["Chaperonin","GroEL","GroES","RuBisCO","Chlamydomonas reinhardtii","Biology","Protein folding","Biogenesis","Chloroplast","Biophysics","Chaperone (clinical)","Escherichia coli","Biochemistry","Photosynthesis","Mutant","Chloroplasts","Ribulose-Bisphosphate Carboxylase","Cryoelectron Microscopy","Chaperonin 60","Group I Chaperonins","Chloroplast Proteins","Protein Subunits","Protein Multimerization","CPN60"],"sdg_mappings":[{"sdg_number":0,"sdg_label":"Life in Land"}],"linked_datasets":[],"clinical_trials":[],"software_tools":[],"database_accessions":[],"source":"live","citation_network_status":"fetched"},"created_at":"2026-08-07T20:20:14.981733Z","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":[]}