FIGURE 4.

Schematic representation of the proposed role of AnfO. Under normal conditions, AnfO blocks the incorporation of FeV‐cofactor into apo‐FeFe protein thereby ensuring the fidelity of FeFe‐cofactor incorporation (rightward arrow). In the absence of AnfO incorporation of FeV‐cofactor is favored leading to the accumulation of a hybrid species (leftward arrow) that cannot reduce N₂. Attachment of the δ subunit requires either FeFe‐cofactor (Pérez‐González et al., 2021) or FeV‐cofactor (Yang et al., 2021)