10ZN

CryoEM structure of Heterologous nitrogenase complex (2:1 A. vinelandii-FeP:G. diazotrophicus-MoFeP) inhibited by BeFx (C2 symmetry)

Summary for 10ZN

• Entry DOI: 10.2210/pdb10zn/pdb
• EMDB information: 75569
• Descriptor: Nitrogenase MoFe protein alpha subunit NifD, BERYLLIUM, IRON/SULFUR CLUSTER, ... (11 entities in total)
• Functional Keywords: nitrogenase, nitrogenase complex, heterologous nitrogenase complex, gluconacetobacter diazotrophicus, azotobacter vinelandii, molybdenum-iron protein, iron protein, mofep, fep, fep-mofep, oxidoreductase
• Biological source: Gluconacetobacter diazotrophicus PA1 5; More
• Total number of polymer chains: 8
• Total formula weight: 358559.24

Authors

Li, Y.,Narehood, S.M.,Cook, B.D.,McGuire, K.L.,Tezcan, F.A.,Herzik Jr., M.A. (deposition date: 2026-02-12, release date: 2026-07-15)

Primary citation

Li, Y.,Narehood, S.M.,Cook, B.D.,McGuire, K.L.,Herzik Jr., M.A.,Tezcan, F.A.
Structural and Functional Characterization of Heterologous Nitrogenase Complexes.
Biochemistry, 2026

PubMed Abstract: Nitrogenase is the only known enzyme that catalyzes the reduction of dinitrogen to ammonia. The most prevalent isozyme, molybdenum nitrogenase, comprises the catalytic molybdenum-iron protein (MoFeP) and the ATP-dependent reductase iron protein (FeP). Although Mo-nitrogenases are widespread across bacteria and archaea and appear to share conserved mechanistic and structural features, FeP and MoFeP show considerable sequence variability across diazotrophs. This raises questions about the conservation of chemomechanical mechanisms coupling FeP-dependent ATP hydrolysis and electron transfer to MoFeP, and about the functional compatibility of nitrogenase components from divergent species. Previous studies showed that some heterologous FeP-MoFeP pairs can functionally complement each other, whereas other pairs lack catalytic activity, but the absence of structural information on such heterologous pairs has limited mechanistic understanding. To this end, we investigated the functional and structural compatibility of FeP and MoFeP from () and (), two phylogenetically and ecologically distinct species. Building on our prior work with -nitrogenase and recently developed cryogenic electron microscopy (cryoEM) protocols, we determined the ADP·BeF-trapped structure of the homologous FeP-MoFeP complex and showed that it adopted the same geometry as its counterpart. Activity measurements showed that heterologous combinations retained 60-80% of homologous catalytic activities despite 30-50% sequence divergence in FeP and MoFeP. High-resolution cryoEM structures of FeP-MoFeP and FeP-MoFeP corroborated these activities and revealed that functional complementation tolerates substantial sequence variation when the core structural elements supporting ATP binding/hydrolysis, protein-protein interaction, electron transfer, and substrate reduction are conserved.

PubMed: 42390130
DOI: 10.1021/acs.biochem.6c00360

Experimental method

ELECTRON MICROSCOPY (2.92 Å)