Abstract
Purine nucleotides are ubiquitous molecules essential for all life. The de novo biosynthesis of purines is a metabolic dependency that is frequently reprogrammed in cancers and is a well-established target for chemotherapies, immune modulation and antivirals. Here, we report cryo-electron microscopy structures of the multi-domain human phosphoribosylformylglycinamidine synthase, a central purine biosynthetic enzyme and foundational feature of the purinosome metabolon. These data capture, the proposed iminophosphate intermediate and provide the structural elucidation of an ammonia channel connecting the active sites of the glutaminase and synthase domains. Analysis of this series of structures and the accompanying biochemical data also reveal the molecular features and transient conformational changes that underlie allosteric regulation and catalytic coupling of the domains. This data resolves several longstanding mechanistic questions about this enzyme class and provides a strong foundation for therapeutic development.
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Data availability
The image files and processed data for the reported macromolecular structures are available in the RSCB PDB and EMDB under the accession codes: 9N9W and EMD-49179; 9NAL and EMD-49198; 9NB3 and EMD-49207. PDB codes of previously published structures used in this study are 3UGJ, 1T3T, 2HS4 and 3UMM. All data needed to evaluate the conclusions in the paper are present in the manuscript, Supplementary Information file, and/or the accompanying source data file. Additional data related to this paper may be requested from the authors. Source Data is provided as a Source Data file. Source data are provided with this paper.
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Acknowledgements
The authors would like to thank the staff at The Hormel Institute Cryo-EM core facility, particularly Janarjan Bhandari, for their help with sample preparation and data collection, as well as all members of the J.B.F. lab for helpful discussions. This work was supported by the National Institute for General Medical Sciences and the National Cancer Institute, of the National Institutes of Health, under grant numbers R35GM124898 and R01CA299056. Partial support for N.S. was provided by an Eagles Fellowship and Paint the Town Pink grant from The Hormel Institute. The funding agencies played no role in the design or execution of this work.
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N.S. Methodology, investigation, formal analysis, validation, writing —preliminary draft, review and editing. W.Z. Methodology, investigation. J.B.F. Conceptualization and design, methodology, supervision, investigation, writing—original draft, review and editing, resources, project leadership, funding acquisition.
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Sharma, N., Zhou, W. & French, J.B. Structural and molecular basis for allosteric regulation and catalytic coupling of human phosphoribosylformylglycinamidine synthase. Nat Commun (2026). https://doi.org/10.1038/s41467-026-69423-y
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DOI: https://doi.org/10.1038/s41467-026-69423-y
