AnfO Controls Fidelity of Nitrogenase FeFe Protein Maturation by Preventing Misincorporation Of FeV-Cofactor

Document Type

Article

Journal/Book Title

Molecular Microbiology

Publication Date

2-27-2022

Publisher

Wiley-Blackwell Publishing Ltd.

Volume

117

Issue

5

First Page

1080

Last Page

1088

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 N2 binding and reduction, are, respectively, designated as FeMo-cofactor, FeV-cofactor, and FeFe-cofactor. Fe-only nitrogenase is a poor catalyst for N2 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 N2. 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.

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