biostudies-literatureUnknown32(7)Markus LMDEidgenössische Technische Hochschule ZürichFonds de recherche du Québec – Nature et technologiesMcGill UniversityCanadian Institutes of Health ResearchCyanophycin is a natural polymer composed of a poly-aspartate backbone with arginine attached to each of the aspartate sidechains. Produced by a wide range of bacteria, which mainly use it as a store of fixed nitrogen, it has many promising industrial applications. Cyanophycin can be synthesized from the amino acids Asp and Arg by the widespread cyanophycin synthetase 1 (CphA1), or from the dipeptide β-Asp-Arg by the cyanobacterial enzyme cyanophycin synthetase 2 (CphA2). CphA2 enzymes display a range of oligomeric states, from dimers to dodecamers. Recently, the crystal structure of a CphA2 dimer was solved but could not be obtained in complex with substrate. Here, we report cryo-EM structures of the hexameric CphA2 from Stanieria sp. at ~2.8 Å resolution, both with and without ATP analogProtein science : a publication of the Protein Societye4685https://www.ebi.ac.uk/biostudies/studies/S-EPMC10273328biostudies-literatureStructure and function of a hexameric cyanophycin synthetase 2.PMC10273328Sharon IMunro KStrauss MHilvert DGrogg MSchmeing TMMarkus LMDfalseStructure and function of a hexameric cyanophycin synthetase 2.Cyanophycin is a natural polymer composed of a poly-aspartate backbone with arginine attached to each of the aspartate sidechains. Produced by a wide range of bacteria, which mainly use it as a store of fixed nitrogen, it has many promising industrial applications. Cyanophycin can be synthesized from the amino acids Asp and Arg by the widespread cyanophycin synthetase 1 (CphA1), or from the dipeptide β-Asp-Arg by the cyanobacterial enzyme cyanophycin synthetase 2 (CphA2). CphA2 enzymes display a range of oligomeric states, from dimers to dodecamers. Recently, the crystal structure of a CphA2 dimer was solved but could not be obtained in complex with substrate. Here, we report cryo-EM structures of the hexameric CphA2 from Stanieria sp. at ~2.8 Å resolution, both with and without ATP analog2023-01-01T00:00:00Z2023 Jul2025-07-10T03:08:12.279Z2025-04-06T12:22:59.303ZS-EPMC102733283722249010.1002/pro.4685