The alternative nitrogenase of Azotobacter chroococcum is a vanadium enzyme

Robson, Richard M.; Eady, Robert R.; Richardson, Toby H.; Miller, Richard W.; Hawkins, Marie; Postgate, J. R.

doi:10.1038/322388a0

Cited by 473 publications

(249 citation statements)

References 18 publications

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“…At that time, the detection of a vanadium-containing nitrogenase was also reported [24,25]. In 1986, the vanadate cofactor was finally confirmed for the vanadiumdependent haloperoxidase from A. nodosum [26] and for the alternative nitrogenase in Azotobacter chroococcum [27]. In parallel, several reports indicated that vanadium was indeed an essential trace element for animals [28], Chlorella [29][30][31][32], Enteromorpha and Fucus [33].…”

Section: Ascophylum Nodosumsupporting

confidence: 48%

Vanadium haloperoxidases: From the discovery 30 years ago to X-ray crystallographic and V K-edge absorption spectroscopic studies

Leblanc

Vilter

Fournier

et al. 2015

Coordination Chemistry Reviews

128

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In the environment, vanadium-dependent haloperoxidases (VHPO) are likely to play a key role in the production of biogenic organo-halogens. These enzymes contain vanadate as a prosthetic group, and catalyze, in the presence of hydrogen peroxide, the oxidation of halide ions (Cl -, Br -or I -). They are classified according to the most electronegative halide that they can oxidize. Since the first discovery of a vanadium bromoperoxidase in the brown alga Ascophyllum nodosum thirty years ago, structural and mechanistic studies have been mainly conducted on two types of VHPO, chloro-and bromoperoxidases, and more recently on a vanadium-dependent iodoperoxidase. In this review, we highlight the main progress obtained on the structure-function relation of these proteins, based on biochemistry, crystallography and X-ray absorption spectroscopy (XAS). The comparison of 3D protein structures of the different VHPO helped identify the residues that govern the molecular mechanisms of catalysis and specificity of VHPO. Vanadium K-edge XAS gave further important insight to understand the fine changes around the vanadium cofactor during the catalytic cycle. The combination of different structural approaches, at different scales of resolution, shed new light on biological vanadium coordination in the active site, and its importance for the catalytic cycle and halide specificity of vanadium haloperoxidases. Keywords (max 6)Vanadium-dependent haloperoxidase, vanadium coordination, crystallographic structure, structural evolution, oligomeric state, X-ray absorption spectroscopy on biological vanadium

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Section: Ascophylum Nodosumsupporting

confidence: 48%

Vanadium haloperoxidases: From the discovery 30 years ago to X-ray crystallographic and V K-edge absorption spectroscopic studies

Leblanc

Vilter

Fournier

et al. 2015

Coordination Chemistry Reviews

128

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“…[10,15] V is also known to be incorporated into enzymes of nitrogenfixing bacteria. [32,33] Bacterial cultures isolated from crude oilcontaminated land have been shown to bioaccumulate vanadium from agar medium at high V concentration. [34] Microorganisms capable of reducing vanadium have been isolated and the possibility of microbial reduction causing precipitation of V in anoxic environments has been recognised.…”

Section: In Situ Profilesmentioning

confidence: 99%

High-resolution two-dimensional quantitative analysis of phosphorus, vanadium and arsenic, and qualitative analysis of sulfide, in a freshwater sediment

2008

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Environmental context. Chemical characterisation of sediment microniches can reveal diagenetic processes that may not be detected by larger-scale analysis. With the development of a new preparation method for a binding phase gel, the technique of diffusive gradients in thin films has been used to demonstrate links between the diagenesis of sulfide, phosphorus, vanadium and arsenic at microniches. Knowledge of these processes may improve predictions of past deposition climates where trace elements are considered as paleoredox proxies. Abstract.Recently introduced techniques that can provide two-dimensional images of solution concentrations in sediments for multiple analytes have revealed discrete sites of geochemical behaviour different from the average for that depth (microniches). We have developed a new preparation method for a binding phase, incorporated in a hydrogel, for the diffusive gradients in thin films (DGT) technique. It allows co-analysis of sulfide and the reactive forms of phosphorus, vanadium and arsenic in the porewaters at the surface of the device. This gel, when dried and analysed using laser ablation mass spectrometry, allows the acquisition of high-resolution sub-millimetre-scale data. The binding phase was deployed within a DGT device in a sediment core collected from a productive lake, Esthwaite Water (UK). Localised removal of phosphate and vanadium from the porewaters has been demonstrated at a microniche of local sulfide production. The possible removal processes, including bacterial uptake and reduction of vanadate to insoluble V III by sulfide, are discussed. Understanding processes occurring at this scale may allow improved prediction of pollutant fate and better prediction of past climates where trace metals are used as paleoredox proxies.

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“…One of the two components of the vnf-encoded complex is an iron (Fe) protein (dinitrogenase reductase 2, encoded by vnfH) that is essentially identical in sequence to the product of nifH, and is cross-functional with it as an electron donor in Anabaena variabilis (Pratte et al, 2006). The other component is a vanadium-iron (V-Fe) protein (dinitrogenase 2, for which vnfDG encodes the fused α-/δ-subunit and vnfK encodes the β-subunit) (Robson et al, 1986(Robson et al, , 1989Joerger et al, 1990;Zehr et al, 2003;Raymond et al, 2004;Boison et al, 2006). In A. variabilis, the vnfEN genes are also essential for N 2 fixation (functioning as a scaffold for catalytic cluster formation), although these genes are apparently absent in many strains of bacteria that utilize this system (e.g.…”

Section: Introductionmentioning

confidence: 99%

“…The three major enzyme complexes for N 2 fixation can be viewed in terms of a cascade of efficiency, with the Mo-dependent (nif-encoded) complex being most efficient, followed by the V-dependent (vnf-encoded) complex, and finally the Fe-dependent (anf-encoded) complex (Robson et al, 1986(Robson et al, , 1989Hales et al, 1986aHales et al, , 1986bChisnell et al, 1988;Eady, 1989Eady, , 2003Eady et al, 1988;Joerger et al, 1990;Walmsley & Kennedy, 1991;Raina et al, 1993;Bellenger et al, 2011). Paradoxically, Mo is the least abundant of the three crucial biometals in the continent crust, whereas V is approximately two orders of magnitude more abundant, and Fe is by far the most abundant of the three (Erickson, 1973;Wedepohl, 1995).…”

Section: Introductionmentioning

confidence: 99%

Lichen-symbiotic cyanobacteria associated withPeltigerahave an alternative vanadium-dependent nitrogen fixation system

Hodkinson

Allen

Forrest

et al. 2014

European Journal of Phycology

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In past decades, environmental nitrogen fixation has been attributed almost exclusively to the action of enzymes in the wellstudied molybdenum-dependent nitrogen fixation system. However, recent evidence has shown that nitrogen fixation by alternative pathways may be more frequent than previously suspected. In this study, the nitrogen fixation systems employed by lichen-symbiotic cyanobacteria were examined to determine whether their diazotrophy can be attributed, in part, to an alternative pathway. The mining of metagenomic data (generated through pyrosequencing) and PCR assays were used to determine which nitrogen-fixation systems are present in cyanobacteria from the genus Nostoc associated with four samples from different geographical regions, representing different lichen-forming fungal species in the genus Peltigera. A metatranscriptomic sequence library from an additional specimen was examined to determine which genes associated with N 2 fixation are transcriptionally expressed. Results indicated that both the standard molybdenum-dependent system and an alternative vanadium-dependent system are present and actively transcribed in the lichen symbiosis. This study shows for the first time that an alternative system is utilized by cyanobacteria associated with fungi. The ability of lichen-associated cyanobacteria to switch between pathways could allow them to colonize a wider array of environments, including habitats characterized by low temperature and trace metal (e.g. molybdenum) availability. We discuss the implications of these findings for environmental studies that incorporate acetylenereduction assay data.

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The alternative nitrogenase of Azotobacter chroococcum is a vanadium enzyme

Cited by 473 publications

References 18 publications

Vanadium haloperoxidases: From the discovery 30 years ago to X-ray crystallographic and V K-edge absorption spectroscopic studies

Vanadium haloperoxidases: From the discovery 30 years ago to X-ray crystallographic and V K-edge absorption spectroscopic studies

High-resolution two-dimensional quantitative analysis of phosphorus, vanadium and arsenic, and qualitative analysis of sulfide, in a freshwater sediment

Lichen-symbiotic cyanobacteria associated withPeltigerahave an alternative vanadium-dependent nitrogen fixation system

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