Reactions with Molecular Hydrogen in Microorganisms:  Evidence for a Purely Organic Hydrogenation Catalyst

Thauer, Rudolf K.; Klein, Andreas R.; Hartmann, Gudrun C.

doi:10.1021/cr9500601

Cited by 254 publications

(253 citation statements)

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“…In contrast, the genes for the F 420 -associated proteins, including Mtd, which functions in the same step with Hmd, were not significantly affected by growth rate. These results suggest that Hmd, which is an unusual iron-sulfur clusterfree hydrogenase (20) with low affinity for hydrogen (21), takes on increasing importance as growth rate increases. Genes for two steps in methanogenesis, formylmethanofuran:tetrahydromethanopterin formyltransferase (Mmp1609) and methenyltetrahydromethanopterin cyclohydrolase (Mmp1191), had Ϸ2-fold increased mRNA levels with increased growth rate ( Fig.…”

Section: Distinct Effect Of H2 Limitation On Genes Encoding F420-depementioning

confidence: 89%

Functionally distinct genes regulated by hydrogen limitation and growth rate in methanogenic Archaea

Hendrickson

Haydock

Moore

et al. 2007

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

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The use of molecular hydrogen as electron donor for energy generation is a defining characteristic of the hydrogenotrophic methanogens, an ancient group that dominates the phylum Euryarchaeota. We present here a global study of changes in mRNA abundance in response to hydrogen availability for a hydrogenotrophic methanogen. Cells of Methanococcus maripaludis were grown by using continuous culture to deconvolute the effects of hydrogen limitation and growth rate, and microarray analyses were conducted. Hydrogen limitation markedly increased mRNA levels for genes encoding enzymes of the methanogenic pathway that reduce or oxidize the electron-carrying deazaflavin, coenzyme F420. F420-dependent redox functions in energy-generating metabolism are characteristic of the methanogenic Archaea, and the results show that their regulation is distinct from other redox processes in the cell. Rapid growth increased mRNA levels of the gene for an unusual hydrogenase, the hydrogen-dependent methylenetetrahydromethanopterin dehydrogenase.coenzyme F420 ͉ microarrays ͉ Methanococcus maripaludis

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Section: Distinct Effect Of H2 Limitation On Genes Encoding F420-depementioning

confidence: 89%

Functionally distinct genes regulated by hydrogen limitation and growth rate in methanogenic Archaea

Hendrickson

Haydock

Moore

et al. 2007

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

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“…H ydrogenases catalyze the reversible oxidation of molecular hydrogen and play a vital role in anaerobic metabolisms of a wide variety of microorganisms (1,2). [NiFe]hydrogenases are particularly interesting because of their heterobinuclear active site and have been studied extensively (3)(4)(5)(6)(7)(8)(9)(10)(11)(12).…”

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confidence: 99%

Modulation of the electronic structure and the Ni–Fe distance in heterobimetallic models for the active site in [NiFe]hydrogenase

Zhu

Marr

Wang

et al. 2005

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

155

154

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Reaction of the mononuclear Ni(II) thiolate complexes [Ni(L)]hydrogenase ͉ iron ͉ nickel ͉ thiolates ͉ density functional theory calculations H ydrogenases catalyze the reversible oxidation of molecular hydrogen and play a vital role in anaerobic metabolisms of a wide variety of microorganisms (1, 2).[NiFe]hydrogenases are particularly interesting because of their heterobinuclear active site and have been studied extensively (3-12). Thiolate-bridged heterobimetallic Ni-Fe complexes, therefore, have also received considerable attention because of their importance as structural, spectroscopic, and functional models for the active site of the enzyme (13-15). The structure of the oxidized inactive form of [NiFe]hydrogenase in Desulfovibrio gigas has been determined by x-ray crystallography (4, 5) and confirms an unusual heterobimetallic Ni-Fe core incorporating two terminal thiolates and two bridging thiolates at the Ni ion, with the bridging thiolates binding to a Fe(CN) 2 (CO) fragment with a Ni-Fe separation of 2.9 Å (Fig. 1). The vast majority of low-molecular-weight mimics have sought to model these structural patterns and this Ni-Fe separation (13-15).Of particular interest to us was the reported x-ray absorption study of [NiFe]hydrogenase from Chromatium vinosum that estimated the Ni-Fe separation as 2.5-2.6 Å in the reduced and active Ni-SI form of the enzyme (16). This finding was further supported by theoretical (17) and mechanistic (18, 19) studies that suggest a shorter Ni-Fe separation (2.5 Å) in the active form of the enzyme compared with that observed in the structure of its oxidized, inactive form (2.9 Å) (4). Furthermore, recent crystal structure determinations of [NiFe]hydrogenases from Desulfovibrio vulgaris Miyazaki F (8) and D. gigas (11) also exhibit shorter Ni-Fe separations (2.55 and 2.53 Å, respectively), while Cramer and coworkers (20) have identified spin-state changes brought about by stereochemical distortion and͞or addition of further ligands at the active site. We therefore were challenged to synthesize low-molecular-weight heterobinuclear Ni-Fe complexes that would mimic not only the short Ni-Fe distance of the Ni-SI, Ni-C, and related reduced centers, but also to model the proposed stereochemical distortions and spin-state changes at the Ni center on binding to Fe fragment(s). Materials and MethodsAll operations were carried out at room temperature under a pure argon atmosphere by using standard Schlenk techniques. [Ni(pdt) (dppe)] (21, 22) and [Fe(CO) 3 (BDA)] (23) (pdt, propanedithiolate; dppe, 1,2-diphenylphosphinoethane; BDA, benzylidene acetone) were prepared by methods described in the literature. Fe 2 (CO) 9 and Fe 3 (CO) 12 were purchased from Aldrich and used as received. All solvents were dried and distilled before use. CH 2 Cl 2 was distilled from CaH 2 and benzene from Na͞benzophenone ketyl under argon. All calculations on complex 3 were carried out with the program ORCA (24). The functional for the geometry optimization was BP86 (25,26), and the basis set was TZVP on lig...

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“…Many methanogenic archaea growing on H 2 and CO 2 contain an unusual hydrogenase without nickel or iron^sulfur clusters [1,2], which was designated metal-free hydrogenase in order to distinguish it from all other hydrogenases that are Fe/S or Ni/Fe/S proteins [3,4]. The metal-free hydrogenase, abbreviated Hmd, catalyzes the reversible reduction of methenyltetrahydromethanopterin with H 2 to methylenetetrahydromethanopterin (vG³P = 35.5 kJ/mol) which is an intermediate reaction in the pathway of methane formation from CO 2 and H 2 [5,6].…”

Section: Introductionmentioning

confidence: 99%

“…The metal-free hydrogenase, abbreviated Hmd, catalyzes the reversible reduction of methenyltetrahydromethanopterin with H 2 to methylenetetrahydromethanopterin (vG³P = 35.5 kJ/mol) which is an intermediate reaction in the pathway of methane formation from CO 2 and H 2 [5,6]. Hmd is composed of only one type of subunit with an apparent molecular mass of approximately 40 kDa and has a speci¢c activity of above 1000 U/mg [7].…”

Section: Introductionmentioning

confidence: 99%

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The metal‐free hydrogenase from methanogenic archaea: evidence for a bound cofactor

2000

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The hmd gene, which encodes the metal-free hydrogenase in methanogenic archaea, was heterologously expressed in Escherichia coli. The overproduced enzyme was completely inactive. High activity could, however, be induced by the addition of ultrafiltrate from active enzyme denatured in 8 M urea. The active fraction in the ultrafiltrate was heat-labile and migrated on gel filtration columns with an apparent molecular mass well below 1000 Da. ß 2000 Federation of European Biochemical Societies. Published by Elsevier Science B.V. All rights reserved.

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Reactions with Molecular Hydrogen in Microorganisms: Evidence for a Purely Organic Hydrogenation Catalyst

Cited by 254 publications

References 50 publications

Functionally distinct genes regulated by hydrogen limitation and growth rate in methanogenic Archaea

Functionally distinct genes regulated by hydrogen limitation and growth rate in methanogenic Archaea

Modulation of the electronic structure and the Ni–Fe distance in heterobimetallic models for the active site in [NiFe]hydrogenase

The metal‐free hydrogenase from methanogenic archaea: evidence for a bound cofactor

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