The final steps of [FeFe]-hydrogenase maturation

Significance The maturation of each hydrogenase class describes the process that converts an apo-hydrogenase into an active holoenzyme involving a machinery of maturases. For [FeFe]-hydrogenases, the synthesis and insertion of the catalytic dinuclear [2FeH ]-cofactor is executed by the 3 maturases (HydE, HydF, and HydG) that have already been studied extensively. However, the final steps of maturation occurring within apo-hydrogenase (cofactor recognition and integration) have not been elucidated yet. Herein, we postulate a molecular mechanism, exemplifying how a synthetic cofactor mimic is directed to its binding cavity, which precisely locks the cofactor to unlock its catalytic potential. Given the striking similarities to the maturation processes of other redox enzymes, these findings illuminate common mechanistic principles that govern cofactor insertion into metalloproteins.