6N4K

Dithionite-reduced nucleotide-free form of the nitrogenase Fe-protein from A. vinelandii

Summary for 6N4K

• Entry DOI: 10.2210/pdb6n4k/pdb
• Descriptor: Nitrogenase iron protein 1, IRON/SULFUR CLUSTER (3 entities in total)
• Functional Keywords: nitrogenase, iron sulfur cluster, oxidoreductase
• Biological source: Azotobacter vinelandii
• Total number of polymer chains: 2
• Total formula weight: 63185.73

Authors

Wenke, B.B.,Spatzal, T.,Rees, D.C. (deposition date: 2018-11-19, release date: 2019-02-13, Last modification date: 2023-10-11)

Primary citation

Wenke, B.B.,Spatzal, T.,Rees, D.C.
Site-Specific Oxidation State Assignments of the Iron Atoms in the [4Fe:4S]2+/1+/0States of the Nitrogenase Fe-Protein.
Angew. Chem. Int. Ed. Engl., 58:3894-3897, 2019

PubMed Abstract: The nitrogenase iron protein (Fe-protein) contains an unusual [4Fe:4S] iron-sulphur cluster that is stable in three oxidation states: 2+, 1+, and 0. Here, we use spatially resolved anomalous dispersion (SpReAD) refinement to determine oxidation assignments for the individual irons for each state. Additionally, we report the 1.13-Å resolution structure for the ADP bound Fe-protein, the highest resolution Fe-protein structure presently determined. In the dithionite-reduced [4Fe:4S] state, our analysis identifies a solvent exposed, delocalized Fe pair and a buried Fe pair. We propose that ATP binding by the Fe-protein promotes an internal redox rearrangement such that the solvent-exposed Fe pair becomes reduced, thereby facilitating electron transfer to the nitrogenase molybdenum iron-protein. In the [4Fe:4S] and [4Fe:4S] states, the SpReAD analysis supports oxidation states assignments for all irons in these clusters of Fe and valence delocalized Fe , respectively.

PubMed: 30698901
DOI: 10.1002/anie.201813966

Experimental method

X-RAY DIFFRACTION (1.756 Å)