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bioRxiv · 10.1101/2021.12.06.471366

Azotobacter vinelandii scaffold protein NifU transfers iron to NifQ as part of the iron-molybdenum cofactor biosynthesis pathway for nitrogenase

Barahona, E.·Jiang, X.·Jimenez-Vicente, E.·Rubio, L. M.·Gonzalez-Guerrero, M.
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Abstract

Azotobacter vinelandii molybdenum-dependent nitrogenase obtains molybdenum from NifQ, a monomeric iron-sulfur molybdoprotein. This protein requires of a preexisting [Fe-S] cluster to form a [MoFe3S4] group to serve as specific donor during nitrogenase cofactor biosynthesis. Here, we show biochemical evidence for NifU being the donor of the [Fe-S] cluster. Protein-protein interaction studies using apo-NifQ and as-isolated NifU demonstrated the interaction between both proteins which is only effective when NifQ is unoccupied by its [Fe-S] cluster. The apo-NifQ iron content increased after the incubation with as-isolated NifU, reaching similar levels to holo-NifQ after the interaction between apo-NifQ and NifU with reconstituted transient [Fe4-S4] groups. These results also indicate the necessity of co-expressing NifU together with NifQ in the pathway to provide molybdenum for the biosynthesis of nitrogenase in engineered nitrogen-fixing plants.

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Barahona, E., Jiang, X., Jimenez-Vicente, E., Rubio, L. M., Gonzalez-Guerrero, M.. 2021-12-06. Azotobacter vinelandii scaffold protein NifU transfers iron to NifQ as part of the iron-molybdenum cofactor biosynthesis pathway for nitrogenase. https://doi.org/10.1101/2021.12.06.471366

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