Fig. 3: NifEN interaction with NifX and transfer of NifB-co.
From: Trafficking of a nitrogenase FeMo-cofactor assembly intermediate
a, Map of the 3D class with NifX present. The map indicates a degree of flexibility of NifX, whose globular domain is only resolved on one side of the C2-symmetric NifEN. b, Density for bound NifB-co on NifX, contacted directly by NifE. c, Structural model of the handover complex for NifB-co, with NifX as ligand to one apical Fe of the cofactor precursor and the N terminus of NifE to the other. d, Electrostatic surface potential for NifX, contoured from −5 kBT (red) to +5 kBT (blue). NifB-co is bound to a distinctly positively charged binding pocket. e, Coordination of NifB-co in the handover complex. The N terminus of NifE is disordered up to residue C25, which serves as an apical cluster ligand. In NifX, H35 coordinates the other apex of NifB-co.
