Perez-Gonzalez, AnaJimenez-Vicente, EmilioSalinero-Lanzarote, AlvaroHarris, Derek F.Seefeldt, Lance C.Dean, Dennis R.2022-07-132022-07-132022-050950-382Xhttp://hdl.handle.net/10919/111233Azotobacter 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 Mo-dependent 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.application/pdfenCreative Commons Attribution 4.0 InternationalAzotobacter vinelandiiFeFe proteinFeV-cofactormetalloproteinnitrogen fixationnitrogenaseArticle - Refereedhttps://doi.org/10.1111/mmi.148901175352206291365-2958