{"doi":"10.1016/j.jbc.2025.110362","title":"Low-mass zinc pools in Escherichia coli: Micromolar concentrations, diverse compositions, and Zn-glutathione dominating under Zn-replete conditions","abstract":"Most zinc in cells is bound to proteins, but a tiny portion is bound to non-proteinaceous Zn complexes coordinated by unidentified metabolites. Such low-mass pools likely play a central role in Zn homeostasis in cells, yet their chemical compositions and concentrations are unestablished. Previous investigations suggest that the collective Zn concentration of so-called \"free\" or \"labile\" pools is femtomolar to picomolar. Here the low-mass Zn pool in E. coli was investigated by isolating cytoplasm from cells grown in media supplemented with increasing concentrations of Zn(acetate) 2 . Gentle cell lysis was demonstrated using Mössbauer spectroscopy. Corresponding isolated cytoplasm contained increasing concentrations of Zn. Equivalent samples were subjected to liquid chromatography with inline ICP-MS detection. Many Zn and S peaks were detected, due to both proteins and the low-mass pool. Zn complexes were largely stable over several days. Cytoplasm had a large binding capacity for aqueous Zn, implying that cells are essentially devoid of aqueous Zn. Other samples were treated with the chelator N,N,N'N'-tetrakis(2-pyridylmethyl) ethylenediamine (TPEN) to evaluate the lability of detected species. TPEN removed Zn from both proteins and pool complexes with about equal propensity. Low-mass zinc complexes were present at μM collective concentrations, orders-of-magnitude higher than previous reports for \"free\" or \"labile\" pools. Two Zn-glutathione (GSH) complexes were identified by electrospray ionization mass spectrometry (ESI-MS) as dominant members of the pool under Zn-replete conditions. Cells do not significantly increase GSH concentrations when exposed to high levels of media Zn; rather, excess imported Zn is sequestered by available GSH.","journal":"Journal of Biological Chemistry","year":2025,"id":541476,"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":2,"citer_count":0,"citers_with_citation_signal":0,"citers_with_endowment":0,"datacite_reuse_total":0,"is_dataset":false,"is_dataset_confidence":0.9443,"is_data_producer":false,"deposit_databanks":null,"is_oa":true,"file_count":0,"downloads":0,"has_version_chain":false,"published_date":"2025-01-01","fair_score":null,"fair_percentile":null,"algorithm_id":"datarank_citation_only_1hop_v6","ranking_scope":"data_only","authors":[{"id":1429797,"name":"Nicholas Romano","orcid":"0000-0003-2765-4912","position":1,"is_corresponding":false},{"id":1056806,"name":"Justin D. Hierholzer","orcid":null,"position":2,"is_corresponding":false},{"id":434341,"name":"Paul A. Lindahl","orcid":"0000-0001-8307-9647","position":3,"is_corresponding":false},{"id":1056386,"name":"Alexia C. Kreinbrink","orcid":"0000-0003-3978-8846","position":0,"is_corresponding":true}],"reference_count":29,"raw_metadata":null,"created_at":"2026-07-19T02:52:47.161928Z","pmid":"40513946","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":[]}