UV‐A/blue‐light inactivation of the ‘metal‐free’ hydrogenase (Hmd) from methanogenic archaea

Lyon, Erica J.; Shima, Seigo; Buurman, Gerrit; Chowdhuri, Shantanu; Batschauer, Alfred; Steinbach, K; Thauer, Rudolf K.

doi:10.1046/j.1432-1033.2003.03920.x

Cited by 200 publications

(222 citation statements)

References 43 publications

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“…Moreover, all other known hydrogenases contain either Fe or Ni, or both, in their active sites (40). This observation includes the so-called ''metal-free'' H 2 -forming methylene tetrahydromethanopterin dehydrogenase of methanogenic archaea, which is now known to contain Fe as well (41). In contrast, BAP contains no redox active metals, although both Zn and Mg are required for hydrolytic activity (27).…”

Section: Pt Oxidation Is Not a Common Feature Of All Alkaline Phosphamentioning

confidence: 99%

A new activity for an old enzyme: Escherichia coli bacterial alkaline phosphatase is a phosphite-dependent hydrogenase

Yang

Metcalf

2004

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

130

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Genetic analysis indicates that Escherichia coli possesses two independent pathways for oxidation of phosphite (Pt) to phosphate. One pathway depends on the 14-gene phn operon, which encodes the enzyme C-P lyase. The other pathway depends on the phoA locus, which encodes bacterial alkaline phosphatase (BAP). Transposon mutagenesis studies strongly suggest that BAP is the only enzyme involved in the phoA-dependent pathway. This conclusion is supported by purification and biochemical characterization of the Pt-oxidizing enzyme, which was proven to be BAP by N terminus protein sequencing. Highly purified BAP catalyzed Pt oxidation with specific activities of 62-242 milliunits͞mg and phosphate ester hydrolysis with specific activities of 41-61 units͞ mg. Surprisingly, BAP catalyzes the oxidation of Pt to phosphate and molecular H 2. Thus, BAP is a unique Pt-dependent, H2-evolving hydrogenase. This reaction is unprecedented in both P and H biochemistry, and it is likely to involve direct transfer of hydride from the substrate to water-derived protons.U nlike the other major elements in living organisms, P is commonly considered to be a redox conservative element. Accordingly, the P centers found in the vast majority of biological intermediates, including inorganic phosphate (P i ), organic phosphate esters, and phosphoanhydrides, are fully oxidized (ϩ5 valence state). Nevertheless, it is now clear, although not widely appreciated, that many organisms are capable of metabolizing reduced P compounds, indicating that P redox reactions are biochemically possible. A wide array of prokaryotic (and some eukaryotic) organisms can synthesize or degrade reduced P compounds (1, 2). Moreover, the widespread occurrence of this trait strongly suggests that a selective advantage is conferred on organisms with the ability to metabolize reduced P compounds. Examination of reduced P metabolism has revealed a wealth of unusual biology and biochemistry. The bacterium Desulfotignum phosphitoxidans gains energy for growth by oxidation of phosphite (Pt) coupled to either sulfate reduction or acetogenesis while fixing CO 2 as its sole C source (3, 4). Many other organisms can use reduced P compounds as sole P sources (5-8). For example, Pseudomonas stutzeri is capable of oxidizing hypophosphite (P valence, ϩ1) to phosphate by means of a Pt (P valence, ϩ3) intermediate (9). The following two enzymes catalyze these reactions: 2-oxoglutarate͞hypophosphite dioxygenase catalyzes the oxidation of hypo-Pt to Pt (10), and Pt͞NAD oxidoreductase catalyzes the oxidation of Pt to phosphate (11). The latter reaction is the most thermodynamically favorable reduction of NAD that is known, and this trait makes this enzyme particularly useful as a cofactor-regenerating catalyst for enzyme-based synthetic strategies (12). P biochemistry can be found also in more familiar organisms, such as Escherichia coli. As shown below, E. coli has two pathways for the oxidation of Pt. Our examination of these pathways demonstrates that thoroughly characterized biochemist...

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Section: Pt Oxidation Is Not a Common Feature Of All Alkaline Phosphamentioning

confidence: 99%

A new activity for an old enzyme: Escherichia coli bacterial alkaline phosphatase is a phosphite-dependent hydrogenase

Yang

Metcalf

2004

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

130

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“…Three classes of hydrogenases can be distinguished according to the metal content of the H 2 (1)(2)(3)(4). 1 Sequence comparisons, structural data, and spectroscopic properties indicate that although these hydrogenases are phylogenetically unrelated, they possess some remarkable similarities in the molecular architecture of the active site, namely the presence of cyanide and/or carbon monoxide as ligands to the metals.…”

Section: Hydrogenases (Reaction H 2 7 Hmentioning

confidence: 99%

“…Most [NiFe]-hydrogenases are reversibly inactivated by oxygen, whereas the [Fe]-hydrogenases are not affected by oxygen (3). Most hydrogenases are inhibited by carbon monoxide.…”

Section: Hydrogenases (Reaction H 2 7 Hmentioning

confidence: 99%

“…Hence, it has been proposed that one or more of the conserved Cys thiols in the HoxH subunit may not be directly coordinated to nickel (27,28). 3 Biosynthesis of the unique Ni-Fe active site is a proteinassisted process. Although we are far from understanding the molecular details of the maturation, advanced studies on hydrogenase-3 of Escherichia coli provided the following model (29,30).…”

Section: Hydrogenases (Reaction H 2 7 Hmentioning

confidence: 99%

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The Auxiliary Protein HypX Provides Oxygen Tolerance to the Soluble [NiFe]-Hydrogenase of Ralstonia eutropha H16 by Way of a Cyanide Ligand to Nickel

Bleijlevens

Buhrke

Linden

et al. 2004

Journal of Biological Chemistry

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The hypX gene of the facultative lithoautotrophic bacterium Ralstonia eutropha is part of a cassette of accessory genes (the hyp cluster) required for the proper assembly of the active site of the [NiFe]-hydrogenases in the bacterium. A deletion of the hypX gene led to a severe growth retardation under lithoautotrophic conditions with 5 or 15% oxygen, when the growth was dependent on the activity of the soluble NAD ؉ -reducing hydrogenase. The enzymatic and infrared spectral properties of the soluble hydrogenase purified from a HypXnegative strain were compared with those from an enzyme purified from a HypX-positive strain. In activity assays under anaerobic conditions both enzyme preparations behaved the same. Under aerobic conditions, however, the mutant enzyme became irreversibly inactivated during H 2 oxidation with NAD ؉ or benzyl viologen as the electron acceptor. Infrared spectra and chemical determination of cyanide showed that one of the four cyanide groups in the wild-type enzyme was missing in the mutant enzyme. The data are consistent with the proposal that the HypX protein is specifically involved in the biosynthetic pathway that delivers the nickel-bound cyanide. The data support the proposal that this cyanide is crucial for the enzyme to function under aerobic conditions. 2 from the ␤-proteobacterium Ralstonia eutropha H16. This is a heterotetrameric enzyme with subunits HoxF (67 kDa), HoxH (55 kDa), HoxU (26 kDa), and HoxY (23 kDa) (9, 10). The enzyme comprises two functionally different heterodimeric complexes, which have been separated and characterized (9, 11). The HoxFU dimer constitutes an enzyme module, termed NADH dehydrogenase or diaphorase, involved in the reduction of NAD Fig. 1A. The bridging oxygen ligand is removed upon reduction, whereby these enzymes become activated (17,24).The SH of R. eutropha belongs to a subclass of [NiFe]-hydrogenases where the polypeptide of the small hydrogenase subunit (HoxY) ends shortly after the position of the fourth Cys residue coordinating the proximal cluster. The large hydrogenase subunit (HoxH) of the SH contains the four Cys residues, conserved in all [NiFe]-hydrogenases, for the binding of the

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“…Furthermore, the turnover number of [Fe] hydrogenases is 10 -100 times higher than that of [NiFe] hydrogenases (9), making the former one of the most efficient H 2 production catalysts known. Hydrogenases containing NiFeSe (10) and a unique class of hydrogenases containing a single Fe atom bound to a co-factor have also been reported (11).…”

mentioning

confidence: 99%

Discovery of Two Novel Radical S-Adenosylmethionine Proteins Required for the Assembly of an Active [Fe] Hydrogenase

Posewitz

King

Smolinski

et al. 2004

Journal of Biological Chemistry

378

385

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To identify genes necessary for the photoproduction of H 2 in Chlamydomonas reinhardtii, random insertional mutants were screened for clones unable to produce H 2 . One of the identified mutants, denoted hydEF-1, is incapable of assembling an active [Fe] hydrogenase. Although the hydEF-1 mutant transcribes both hydrogenase genes and accumulates full-length hydrogenase protein, H 2 production activity is not observed. The HydEF protein contains two unique domains that are homologous to two distinct prokaryotic proteins, HydE and HydF, which are found exclusively in organisms containing [Fe] hydrogenase. In the C. reinhardtii genome, the HydEF gene is adjacent to another hydrogenase-related gene, HydG. Hydrogen has enormous potential to serve as a non-polluting fuel, alleviating the environmental and political concerns associated with fossil energy utilization. Among the most efficient H 2 -generating catalysts known are the [Fe] hydrogenase enzymes, which are found in numerous microorganisms, including the photosynthetic green alga Chlamydomonas reinhardtii (1, 2). Our research, aimed at identifying accessory proteins required for H 2 production in C. reinhardtii, has resulted in the discovery of two [Fe] hydrogenase assembly genes. These genes are essential for the formation of an active [Fe] hydrogenase and are conserved among sequenced organisms containing [Fe] hydrogenase enzymes.Algal H 2 production was first reported by Hans Gaffron and co-workers in seminal experiments performed over 60 years ago (3). Photosynthetic green algae are unique in that H 2 production by [Fe] hydrogenases is coupled directly to water oxidation through photosystem II and the photosynthetic electron transport chain, providing the means to generate H 2 using sunlight. In the past 5 years, great strides have been made in sustaining H 2 photoproduction activity in C. reinhardtii (4, 5), and intensive research continues to probe novel ways to use this and other photosynthetic organisms to generate renewable H 2 .Hydrogenases containing metallo-catalytic clusters occur as [NiFe] or [Fe]-only enzymes (2, 6, 7). These two forms are phylogenetically distinct (8), which suggests that hydrogenase function is the result of convergent evolution (2). Although [NiFe] and [Fe] hydrogenases are genetically unrelated, similarities between the proteins do exist. First, the active sites of both enzymes contain CO and CN ligands, and, second, each active site contains a binuclear metal center. In general, [NiFe] hydrogenases catalyze H 2 uptake, whereas [Fe] hydrogenases tend to catalyze H 2 evolution (9). Furthermore, the turnover number of [Fe] hydrogenases is 10 -100 times higher than that of [NiFe] hydrogenases (9), making the former one of the most efficient H 2 production catalysts known. Hydrogenases containing NiFeSe (10) and a unique class of hydrogenases containing a single Fe atom bound to a co-factor have also been reported (11).The [NiFe] hydrogenases are found in a variety of anaerobic and facultative archaea, eubacteria, a...

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UV‐A/blue‐light inactivation of the ‘metal‐free’ hydrogenase (Hmd) from methanogenic archaea

Cited by 200 publications

References 43 publications

A new activity for an old enzyme: Escherichia coli bacterial alkaline phosphatase is a phosphite-dependent hydrogenase

A new activity for an old enzyme: Escherichia coli bacterial alkaline phosphatase is a phosphite-dependent hydrogenase

The Auxiliary Protein HypX Provides Oxygen Tolerance to the Soluble [NiFe]-Hydrogenase of Ralstonia eutropha H16 by Way of a Cyanide Ligand to Nickel

Discovery of Two Novel Radical S-Adenosylmethionine Proteins Required for the Assembly of an Active [Fe] Hydrogenase

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