9IAN

Nitrogenase maturase NifEN in complex with the cofactor chaperone NifX

Summary for 9IAN

• Entry DOI: 10.2210/pdb9ian/pdb
• EMDB information: 52782
• Descriptor: Nitrogenase iron-molybdenum cofactor biosynthesis protein NifE, Nitrogenase iron-molybdenum cofactor biosynthesis protein NifN, Nitrogenase MoFe cofactor biosynthesis protein NifX, ... (7 entities in total)
• Functional Keywords: nitrogenase cofactor maturase, metal binding protein
• Biological source: Azotobacter vinelandii DJ; More
• Total number of polymer chains: 6
• Total formula weight: 234893.10

Authors

Schneider, F.F.,Martin del Campo, J.S.,Zhang, L.,Dean, D.R.,Einsle, O. (deposition date: 2025-02-11, release date: 2026-03-04, Last modification date: 2026-05-13)

Primary citation

Schneider, F.F.,Martin Del Campo, J.S.,Zhang, L.,Dean, D.R.,Einsle, O.
Trafficking of a nitrogenase FeMo-cofactor assembly intermediate.
Nat.Chem.Biol., 22:822-828, 2026

PubMed Abstract: The maturation of the unique FeMo-cofactor of molybdenum nitrogenase is a multistep process requiring the sequential action of a series of maturase complexes. As a final step, the NifEN complex forms FeMo-cofactor from the precursor NifB-co, also called L-cluster, through replacement of an apical iron ion by molybdenum and the attachment of an organic homocitrate ligand. NifB-co is delivered by a small cofactor chaperone, NifX, and initially bound near the surface of the maturase NifEN. Here, we report high-resolution cryo-electron microscopy structures of NifEN in complex with NifX, showing NifB-co binding to NifEN in full detail, capturing both interacting partners in the act of cluster transfer. In a dynamic transfer complex, the large metal cluster is coordinated by single residues from both NifEN and NifX. In silico studies concur with these structures but suggest a third, internal conversion site where cluster maturation likely takes place.

PubMed: 41872497
DOI: 10.1038/s41589-026-02179-0

Experimental method

ELECTRON MICROSCOPY (2.16 Å)