Carbonyl sulfide and carbon dioxide as new substrates, and carbon disulfide as a new inhibitor, of nitrogenase

Seefeldt, Lance C.; Rasche, Madeline E.; Ensign, Scott A.

doi:10.1021/bi00016a009

Cited by 105 publications

(116 citation statements)

References 43 publications

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“…The observation that ΔnifH MoFe protein is capable of reducing CO to hydrocarbons raises the question of whether this protein can generate hydrocarbons from CO 2 , particularly given the previous observation that the wild-type MoFe protein can reduce CO 2 to CO (21). Indeed, when a mixture of carbon dioxide/bicarbonate (CO 2 /HCO 3 − ) is used as a substrate, C 2 H 4 , C 2 H 6 , C 3 H 6 , and C 3 H 8 are detected as products in the Eu(II)-DTPA-driven, ΔnifH MoFe protein-based reaction (Fig.…”

Section: Resultsmentioning

confidence: 99%

ATP-independent substrate reduction by nitrogenase P-cluster variant

Lee

Ribbe

2012

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

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The P-cluster of nitrogenase is largely known for its function to mediate electron transfer to the active cofactor site during catalysis. Here, we show that a P-cluster variant (designated P*-cluster), which consists of paired [Fe 4 S 4 ]-like clusters, can catalyze ATP-independent substrate reduction in the presence of a strong reductant, europium (II) diethylenetriaminepentaacetate [Eu(II)-DTPA]. The observation of a decrease of activity in the rank ΔnifH, ΔnifBΔnifZ, and ΔnifB MoFe protein, which corresponds to a decrease of the amount of P*-clusters in these cofactor-deficient proteins, firmly establishes P*-cluster as a catalytically active metal center in Eu(II)-DTPA-driven reactions. More excitingly, the fact that P*-cluster is not only capable of catalyzing the two-electron reduction of proton, acetylene, ethylene, and hydrazine, but also capable of reducing cyanide, carbon monoxide, and carbon dioxide to alkanes and alkenes, points to a possibility of developing biomimetic catalysts for hydrocarbon production under ambient conditions.N itrogenases are a family of metalloenzymes that catalyze the nucleotide-dependent reduction of dinitrogen to ammonia under ambient conditions. The best-characterized member of this enzyme family is the molybdenum (Mo)-nitrogenase of Azotobacter vinelandii, which consists of two redox-active component proteins (1). One of the proteins, termed iron (Fe) protein (encoded by nifH), is a γ 2 -dimer that contains a [Fe 4 S 4 ] cluster between the two subunits and a MgATP binding site within each subunit; the other, termed molybdenum-iron (MoFe) protein (encoded by nifDK), is an α 2 β 2 -heterotetramer that houses two complex metal clusters per αβ-dimer: the P-cluster ([Fe 8 S 7 ]), which is located at each α/β-subunit interface; and the iron-molybdenum (FeMo) cofactor, or FeMoco ([MoFe 7 S 9 C-homocitrate]), which is buried within each α-subunit (2-4). Catalysis by nitrogenase presumably involves repeated association and dissociation between the two component proteins and ATP-dependent electron transfer from the [Fe 4 S 4 ] cluster of the Fe protein, through the P-cluster, to the FeMoco of MoFe protein, where substrate reduction occurs (5).The P-cluster has long been regarded as a "capacitor" that mediates the electron transfer between the [Fe 4 S 4 ] cluster of Fe protein and the cofactor site of MoFe protein during catalysis (1). Although the question of whether the P-cluster can directly reduce substrates was raised previously, it has remained a topic of debate because of the difficulty of distinguishing the contribution of the P-cluster from that of the cofactor to catalysis. As such, MoFe protein variants carrying the P-cluster species alone need to be generated to address the catalytic capacity of P-cluster. Recent studies of the biosynthesis of nitrogenase have led to the identification of three cofactor-deficient forms of MoFe protein (Fig. 1). One form, designated ΔnifB MoFe protein, contains two intact, [Fe 8 S 7 ] P-clusters (6); another, designated ΔnifH MoFe pro...

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Section: Resultsmentioning

confidence: 99%

ATP-independent substrate reduction by nitrogenase P-cluster variant

Lee

Ribbe

2012

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

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“…A number of enzymes besides CA have affinity to OCS as a substrate, such as RuBisCO (Lorimer & Pierce, 1989), carbon monoxide dehydrogenase (Ensign, 1995), nitrogenase (Seefeldt et al, 1995), OCS 15 hydrolase (Ogawa et al, 2013), and CS 2 hydrolase (Smeulders et al, 2011), but their impact on total soil OCS consumption has not been assessed. A few studies have linked specific microbial groups, including T. thioparus (Ogawa et al, 2013), Actinobacteria (Kato et al, 2008;Ogawa et al, 2016), and Ascomycota (fungi) (Masaki et al, 2016), to the degradation of atmospheric OCS.…”

Section: Ocs To Probe Variables Other Than Gppmentioning

confidence: 99%

Reviews and Syntheses: Carbonyl Sulfide as a Multi-scale Tracer for Carbon and Water Cycles

Whelan¹,

Lennartz²,

Gimeno³

et al. 2017

Preprint

113

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Abstract. For the past decade, observations of carbonyl sulfide (OCS or COS) have been investigated as a proxy for carbon uptake by plants. OCS is destroyed by enzymes that interact with CO 2 during 25 photosynthesis, namely carbonic anhydrase (CA) and RuBisCO, where CA is the more important. The majority of sources of OCS to the atmosphere are geographically separated from this large plant sink, whereas the sources and sinks of CO 2 are co-located in ecosystems. The drawdown of OCS can therefore be related to the uptake of CO 2 without the added complication of co-located emissions comparable in magnitude. Here we review the state of our understanding of the global OCS cycle and 30 its applications to ecosystem carbon cycle science. OCS uptake is correlated well to plant carbon uptake, especially at the regional scale. OCS can be used in conjunction with other independent measures of ecosystem function, like solar-induced fluorescence and carbon and water isotope studies.More work needs to be done to generate global coverage for OCS observations and to link this powerful Biogeosciences Discuss., https://doi

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“…Seefeldt and co-workers have shown that CO 2 is slowly reduced to CO by the nitrogenase enzyme. 58 Complexes 1a and 1b each react with 2 equiv of carbon dioxide at room temperature, generating yellow solids that are formulated as formate-bridging diiron complexes (10a, 10b) based on X-ray crystallography (Figure 10). Only a few crystallographically characterized η 2 -formato bridging iron complexes have been reported in the literature.…”

Section: Ironmentioning

confidence: 99%

The Reactivity Patterns of Low-Coordinate Iron−Hydride Complexes

Sadique²,

Smith³

et al. 2008

J. Am. Chem. Soc.

183

177

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Abstract:We report a survey of the reactivity of the first isolable iron-hydride complexes with a coordination number less than 5. The high-spin iron(II) complexes [( -diketiminate)Fe(µ-H)] 2 react rapidly with representative cyanide, isocyanide, alkyne, N 2, alkene, diazene, azide, CO2, carbodiimide, and Brønsted acid containing substrates. The reaction outcomes fall into three categories: (1) addition of Fe-H across a multiple bond of the substrate, (2) reductive elimination of H 2 to form iron(I) products, and (3) protonation of the hydride to form iron(II) products. The products include imide, isocyanide, vinyl, alkyl, azide, triazenido, benzo[c]cinnoline, amidinate, formate, and hydroxo complexes. These results expand the range of known bond transformations at iron complexes. Additionally, they give insight into the elementary transformations that may be possible at the iron-molybdenum cofactor of nitrogenases, which may have hydride ligands on high-spin, low-coordinate metal atoms.

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Carbonyl sulfide and carbon dioxide as new substrates, and carbon disulfide as a new inhibitor, of nitrogenase

Cited by 105 publications

References 43 publications

ATP-independent substrate reduction by nitrogenase P-cluster variant

ATP-independent substrate reduction by nitrogenase P-cluster variant

Reviews and Syntheses: Carbonyl Sulfide as a Multi-scale Tracer for Carbon and Water Cycles

The Reactivity Patterns of Low-Coordinate Iron−Hydride Complexes

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