Role for the nitrogenase MoFe protein α-subunit in FeMo-cofactor binding and catalysis
- 1 January 1990
- journal article
- research article
- Published by Springer Nature in Nature
- Vol. 343 (6254) , 188-190
- https://doi.org/10.1038/343188a0
Abstract
TWO components constitute Mo-dependent nitrogenase (EC 1.18.6.1)— the Fe protein (a homodimer encoded by nifH) and the MoFe protein (an α2β2 tetramer encoded by nifDK). The MoFe protein provides the substrate-binding site1–3 and probably coná-tains six prosthetic groups of two types—four Fe-S centres and two Fe- and Mo-containing cofactors4,5. To determine the distribution and catalytic function of these metalloclusters, we6,7 and others8 are attempting to change the catalytic and spectroscopic features of nitrogenase by substituting specific amino acids targeted as potential metallocluster ligands, particularly those to the FeMo-cofactor, which is responsible for the biologically unique electron paramagnetic resonance signal (S =3/2) of nitrogenase9,10, and is believed to be the N2-reducing site11. Here we describe mutant strains of Azotobacter vinelandii that have single a mi no-acid substitutions within the MoFe protein α-subunit. These substitutions alter both substrate-reduction properties and the unique electron paramagnetic resonance signal, indicating that the FeMo-cofactor is associated with both the α-subunit and the substrate-reducing site.Keywords
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