5KOH

Nitrogenase MoFeP from Gluconacetobacter diazotrophicus in dithionite reduced state

Summary for 5KOH

• Entry DOI: 10.2210/pdb5koh/pdb
• Related: 1QGU 1QH1 2MIN 3MIN 3U7Q 4WES 5KOJ
• Descriptor: Nitrogenase protein alpha chain, Nitrogenase FeMo beta subunit protein NifK, 3-HYDROXY-3-CARBOXY-ADIPIC ACID, ... (9 entities in total)
• Functional Keywords: nitrogenase, electron transfer, oxidoreductase, p-cluster
• Biological source: Gluconacetobacter diazotrophicus (strain ATCC 49037 / DSM 5601 / PAl5); More
• Total number of polymer chains: 4
• Total formula weight: 230175.45

Authors

Owens, C.P.,Tezcan, F.A. (deposition date: 2016-06-30, release date: 2016-09-21, Last modification date: 2023-10-04)

Primary citation

Owens, C.P.,Katz, F.E.,Carter, C.H.,Oswald, V.F.,Tezcan, F.A.
Tyrosine-Coordinated P-Cluster in G. diazotrophicus Nitrogenase: Evidence for the Importance of O-Based Ligands in Conformationally Gated Electron Transfer.
J.Am.Chem.Soc., 138:10124-10127, 2016

PubMed Abstract: The P-cluster is a unique iron-sulfur center that likely functions as a dynamic electron (e(-)) relay site between the Fe-protein and the catalytic FeMo-cofactor in nitrogenase. The P-cluster has been shown to undergo large conformational changes upon 2-e(-) oxidation which entail the coordination of two of the Fe centers to a Ser side chain and a backbone amide N, respectively. Yet, how and if this 2-e(-) oxidized state (P(OX)) is involved in catalysis by nitrogenase is not well established. Here, we present the crystal structures of reduced and oxidized MoFe-protein (MoFeP) from Gluconacetobacter diazotrophicus (Gd), which natively possesses an Ala residue in the position of the Ser ligand to the P-cluster. While reduced Gd-MoFeP is structurally identical to previously characterized counterparts around the FeMo-cofactor, oxidized Gd-MoFeP features an unusual Tyr coordination to its P-cluster along with ligation by a backbone amide nitrogen. EPR analysis of the oxidized Gd-MoFeP P-cluster confirmed that it is a 2-e(-) oxidized, integer-spin species. Importantly, we have found that the sequence positions corresponding to the Ser and Tyr ligands are almost completely covariant among Group I nitrogenases. These findings strongly support the possibility that the P(OX) state is functionally relevant in nitrogenase catalysis and that a hard, O-based anionic ligand serves to stabilize this state in a switchable fashion.

PubMed: 27487256
DOI: 10.1021/jacs.6b06783

Experimental method

X-RAY DIFFRACTION (1.83 Å)