{"doi":"10.1073/pnas.2410995121","title":"Capturing a methanogenic carbon monoxide dehydrogenase/acetyl-CoA synthase complex via cryogenic electron microscopy","abstract":"Approximately two-thirds of the estimated one-billion metric tons of methane produced annually by methanogens is derived from the cleavage of acetate. Acetate is broken down by a Ni-Fe-S-containing A-cluster within the enzyme acetyl-CoA synthase (ACS) to carbon monoxide (CO) and a methyl group (CH 3 + ). The methyl group ultimately forms the greenhouse gas methane, whereas CO is converted to the greenhouse gas carbon dioxide (CO 2 ) by a Ni-Fe-S-containing C-cluster within the enzyme carbon monoxide dehydrogenase (CODH). Although structures have been solved of CODH/ACS from acetogens, which use these enzymes to make acetate from CO 2 , no structure of a CODH/ACS from a methanogen has been reported. In this work, we use cryo-electron microscopy to reveal the structure of a methanogenic CODH and CODH/ACS from Methanosarcina thermophila ( Met CODH/ACS). We find that the N-terminal domain of acetogenic ACS, which is missing in all methanogens, is replaced by a domain of CODH. This CODH domain provides a channel for CO to travel between the two catalytic Ni-Fe-S clusters. It generates the binding surface for ACS and creates a remarkably similar CO alcove above the A-cluster using residues from CODH rather than ACS. Comparison of our Met CODH/ACS structure with our Met CODH structure reveals a molecular mechanism to restrict gas flow from the CO channel when ACS departs, preventing CO escape into the cell. Overall, these long-awaited structures of a methanogenic CODH/ACS reveal striking functional similarities to their acetogenic counterparts despite a substantial difference in domain organization.","journal":"Proceedings of the National Academy of Sciences","year":2024,"id":425243,"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":0.9488,"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":948415,"name":"David A. Grahame","orcid":"0000-0002-8292-4690","position":1,"is_corresponding":false},{"id":241330,"name":"Catherine L. Drennan","orcid":"0000-0001-5486-2755","position":2,"is_corresponding":false},{"id":820698,"name":"Alison Biester","orcid":"0000-0003-4129-1871","position":0,"is_corresponding":true}],"reference_count":81,"raw_metadata":{"citation_network_status":"fetched"},"created_at":"2026-07-19T01:58:26.927596Z","pmid":"39361653","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":[]}