The Sixteenth Iron in the Nitrogenase MoFe Protein

Zhang, Limei; Kaiser, Jens T.; Meloni, Gabriele; Yang, Kun Yun; Spatzal, Thomas; Andrade, Susana L. A.; Einsle, Oliver; Howard, James B.; Rees, Douglas C.

doi:10.1002/anie.201303877

Cited by 30 publications

(37 citation statements)

References 30 publications

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“…The site-specific Fe K-edge X-ray absorption near-edge spectrum of Fe16 in Cp1 matches those of both Av1 and ferrous sulfate well, but not that of ferric sulfate, indicating that Fe16 in Cp1 is also a ferrous Fe ( Fig. 5b; Zhang et al, 2013). The occupancy of Fe16 in Cp1 was quantified by electron density and by an Fe K absorption-edge jump as described previously using seven sets of MAD data collected from different Cp1 crystals (Zhang et al, 2013).…”

Section: The Fe16 Sitementioning

confidence: 90%

“…5b; Zhang et al, 2013). The occupancy of Fe16 in Cp1 was quantified by electron density and by an Fe K absorption-edge jump as described previously using seven sets of MAD data collected from different Cp1 crystals (Zhang et al, 2013). We found, using either method, that Fe16 in Cp1 is about half occupied with little variation between crystals (Supplementary Table S4).…”

Section: The Fe16 Sitementioning

confidence: 97%

“…Recently, we have reported a 16th Fe (designated Fe16) in the mononuclear metal-binding site (MMB site) of Av1 between the two -subunits (Zhang et al, 2013). Fe16 in Av1, a partially occupied ferrous Fe, exhibits an approximately octahedral geometry coordinated by the side-chain O atoms of three Glu/Asp residues, the backbone carbonyl O atom of Arg and two water molecules.…”

Section: The Fe16 Sitementioning

confidence: 99%

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Nitrogenase MoFe protein fromClostridium pasteurianumat 1.08 Å resolution: comparison with theAzotobacter vinelandiiMoFe protein

Zhang

Morrison

Kaiser

et al. 2015

Acta Cryst D Biol Crystallogr

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Section: The Fe16 Sitementioning

confidence: 90%

Section: The Fe16 Sitementioning

confidence: 97%

Section: The Fe16 Sitementioning

confidence: 99%

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Nitrogenase MoFe protein fromClostridium pasteurianumat 1.08 Å resolution: comparison with theAzotobacter vinelandiiMoFe protein

Zhang

Morrison

Kaiser

et al. 2015

Acta Cryst D Biol Crystallogr

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“…MAD has been utilized extensively in polycrystalline systems (14-18) but only scarcely in single-crystal experiments (19)(20)(21)(22)(23)(24)(25)(26). Given the dearth of literature surrounding single-molecule, single-crystal MAD applications, we were interested in applying the methodology to a family of well-defined clusters to examine how well this technique can resolve differences in atomic scattering factors and what molecular features affect the scattering factors themselves.…”

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confidence: 99%

Exposing the inadequacy of redox formalisms by resolving redox inequivalence within isovalent clusters

Bartholomew

Teesdale

Sánchez

et al. 2019

Proc. Natl. Acad. Sci. U.S.A.

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In this report we examine a family of trinuclear iron complexes by multiple-wavelength, anomalous diffraction (MAD) to explore the redox load distribution within cluster materials by the free refinement of atomic scattering factors. Several effects were explored that can impact atomic scattering factors within clusters, including 1) metal atom primary coordination sphere, 2) M−M bonding, and 3) redox delocalization in formally mixed-valent species. Complexes were investigated which vary from highly symmetric to fully asymmetric by 57Fe Mössbauer and X-ray diffraction to explore the relationship between MAD-derived data and the data available from these widely used characterization techniques. The compounds examined include the all-ferrous clusters [nBu4N][(tbsL)Fe3(μ3–Cl)] (1) ([tbsL]6– = [1,3,5-C6H9(NC6H4-o-NSitBuMe2)3]6–]), (tbsL)Fe3(py) (2), [K(C222)]2[(tbsL)Fe3(μ3–NPh)] (4) (C222 = 2,2,2-cryptand), and the mixed-valent (tbsL)Fe3(μ3–NPh) (3). Redox delocalization in mixed-valent 3 was explored with cyclic voltammetry (CV), zero-field 57Fe Mössbauer, near-infrared (NIR) spectroscopy, and X-ray crystallography techniques. We find that the MAD results show an excellent correspondence to 57Fe Mössbauer data; yet also can distinguish between subtle changes in local coordination geometries where Mössbauer cannot. Differences within aggregate oxidation levels are evident by systematic shifts of scattering factor envelopes to increasingly higher energies. However, distinguishing local oxidation levels in iso- or mixed-valent materials can be dramatically obscured by the degree of covalent intracore bonding. MAD-derived atomic scattering factor data emphasize in-edge features that are often difficult to analyze by X-ray absorption near edge spectroscopy (XANES). Thus, relative oxidation levels within the cluster were most reliably ascertained from comparing the entire envelope of the atomic scattering factor data.

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“…[26] TheS pReAD method has previously been used to identify the reduced Fe site in the [2Fe:2S] 1+ cluster of aferredoxin [22] from Aquifex aeolicus,aswell as Fe oxidation states in the resting form of FeMoco [23] and amononuclear Fe site in the Azotobacter vinelandii MoFe-protein. [27] Herein, we present ac omprehensive redox description of the A. vinelandii Fe-protein [4Fe:4S] cluster in its three possible oxidation states.…”

Section: Biologicalnitrogenfixationisamulti-electronredoxprocessmentioning

confidence: 99%

Site‐Specific Oxidation State Assignments of the Iron Atoms in the [4Fe:4S]^2+/1+/0 States of the Nitrogenase Fe‐Protein

2019

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The nitrogenase iron protein (Fe-protein) contains an unusual [4Fe:4S] iron-sulphur cluster that is stable in three oxidation states:2 + ,1 + ,a nd 0. Here,w eu se spatially resolved anomalous dispersion (SpReAD) refinement to determine oxidation assignments for the individual irons for each state.A dditionally,w er eport the 1.13-resolution structure for the ADP bound Fe-protein, the highest resolution Fe-protein structure presently determined. In the dithionitereduced [4Fe:4S] 1+ state,o ur analysis identifies as olvent exposed, delocalized Fe 2.5+ pair and ab uried Fe 2+ pair.W e propose that ATPb inding by the Fe-protein promotes an internal redoxrearrangement such that the solvent-exposed Fe pair becomes reduced, therebyf acilitating electron transfer to the nitrogenase molybdenum iron-protein. In the [4Fe:4S] 0 and [4Fe:4S] 2+ states,t he SpReAD analysis supports oxidation states assignments for all irons in these clusters of Fe 2+ and valence delocalized Fe 2.5+ ,respectively.

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The Sixteenth Iron in the Nitrogenase MoFe Protein

Cited by 30 publications

References 30 publications

Nitrogenase MoFe protein fromClostridium pasteurianumat 1.08 Å resolution: comparison with theAzotobacter vinelandiiMoFe protein

Nitrogenase MoFe protein fromClostridium pasteurianumat 1.08 Å resolution: comparison with theAzotobacter vinelandiiMoFe protein

Exposing the inadequacy of redox formalisms by resolving redox inequivalence within isovalent clusters

Site‐Specific Oxidation State Assignments of the Iron Atoms in the [4Fe:4S]^2+/1+/0 States of the Nitrogenase Fe‐Protein

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The Sixteenth Iron in the Nitrogenase MoFe Protein

Cited by 30 publications

References 30 publications

Nitrogenase MoFe protein fromClostridium pasteurianumat 1.08 Å resolution: comparison with theAzotobacter vinelandiiMoFe protein

Nitrogenase MoFe protein fromClostridium pasteurianumat 1.08 Å resolution: comparison with theAzotobacter vinelandiiMoFe protein

Exposing the inadequacy of redox formalisms by resolving redox inequivalence within isovalent clusters

Site‐Specific Oxidation State Assignments of the Iron Atoms in the [4Fe:4S]2+/1+/0 States of the Nitrogenase Fe‐Protein

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Product

Resources

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Site‐Specific Oxidation State Assignments of the Iron Atoms in the [4Fe:4S]^2+/1+/0 States of the Nitrogenase Fe‐Protein