Poly-γ-glutamylation of biomolecules

• Published in: Nature communications 2024-02, Vol.15 (1), p.1310-1310, Article 1310
• Main Authors: Bashiri, Ghader, Bulloch, Esther M. M., Bramley, William R., Davidson, Madison, Stuteley, Stephanie M., Young, Paul G., Harris, Paul W. R., Naqvi, Muhammad S. H., Middleditch, Martin J., Schmitz, Michael, Chang, Wei-Chen, Baker, Edward N., Squire, Christopher J.
• Format: Article
• Language: English
• Subjects: 631/45/173; 631/45/535/1266; 631/45/607; 82/16; 82/29; 82/58; 82/6; 82/80; 82/83; Archaea; Biomolecules; Cofactors; Enzymes; Folic acid; Folylpolyglutamate synthase; Glutamates; Glutamic acid; Humanities and Social Sciences; multidisciplinary; Science; Science (multidisciplinary); Species diversity; Substrate specificity; Substrates
• ISSN: 2041-1723; 2041-1723
• DOI: 10.1038/s41467-024-45632-1

Poly-γ-glutamate tails are a distinctive feature of archaeal, bacterial, and eukaryotic cofactors, including the folates and F 420 . Despite decades of research, key mechanistic questions remain as to how enzymes successively add glutamates to poly-γ-glutamate chains while maintaining cofactor specificity. Here, we show how poly-γ-glutamylation of folate and F 420 by folylpolyglutamate synthases and γ-glutamyl ligases, non-homologous enzymes, occurs via processive addition of L -glutamate onto growing γ-glutamyl chain termini. We further reveal structural snapshots of the archaeal γ-glutamyl ligase (CofE) in action, crucially including a bulged-chain product that shows how the cofactor is retained while successive glutamates are added to the chain terminus. This bulging substrate model of processive poly-γ-glutamylation by terminal extension is arguably ubiquitous in such biopolymerisation reactions, including addition to folates, and demonstrates convergent evolution in diverse species from archaea to humans. Poly-γ-glutamate tails are a distinctive feature of folate and F 420 cofactors, but it was unclear how these tails elongate while maintaining substrate specificity. Here, the authors discover that folylpolyglutamate synthase and γ-glutamyl ligase enzymes add successive L -glutamates to the termini of the growing γ-glutamyl chain in a processive mechanism.