Fig. 4: MAR cryo-EM structure and nitrogenase superfamily architecture.

a, Cryo-EM electron density map contoured at 7 sigma and corresponding structural model for MarDK in the oxidized state with locations of MAR metallocofactors (mar1, mar2) indicated (Figs. 5 and 6). b–d, Structural comparisons of Fe N2ase (Anf; 8OIE)26 (b), Mo N2ase (Nif; 8CRS)71 (c) and DPOR (Chl; 2XDQ)72 (d). Relevant metallocofactors are indicated.