AnfO controls fidelity of nitrogenase FeFe protein maturation by preventing misincorporation of FeV‐cofactor

Abstract

Azotobacter vinelandii produces three genetically distinct, but structurally and mechanistically similar nitrogenase isozymes designated as Mo-dependent, V-dependent, or Fe-only based on the heterometal contained within their associated active site cofactors. These catalytic cofactors, which provide the site for N 2 binding and reduction, are, respectively, designated as FeMo-cofactor, FeV-cofactor, and FeFe-cofactor.Fe-only nitrogenase is a poor catalyst for N 2 fixation, when compared to the Modependent and V-dependent nitrogenases and is only produced when neither Mo nor V is available. Under conditions favoring the production of Fe-only nitrogenase a gene product designated AnfO preserves the fidelity of Fe-only nitrogenase by preventing the misincorporation of FeV-cofactor, which results in the accumulation of a hybrid enzyme that cannot reduce N 2 . These results are interpreted to indicate that AnfO controls the fidelity of Fe-only nitrogenase maturation during the physiological transition from conditions that favor V-dependent nitrogenase utilization to Fe-only nitrogenase utilization to support diazotrophic growth.

Engineering of a photosynthetic diazotroph as biofertilizer for efficient nitrogen fixation powered by sunlight

“…5a). The anf123 genes is supposed to be responsible for the delity of Fe-only nitrogenase maturation [32]. All of the three mutants produced H 2 and CH 4 , and exhibited acetylene reduction activity in the presence of ammonium (Fig.…”