Ribonucleotide reductase of <i>Brevibacterium ammoniagenes</i> is a manganese enzyme

Willing, A.; Follmann, Hartmut; Auling, Georg

doi:10.1111/j.1432-1033.1988.tb13740.x

Cited by 175 publications

(146 citation statements)

References 36 publications

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“…Only three such examples of redox-active polynuclear Mn enzymes are known: Mn-catalase that disproportionates hydrogen peroxide [23][24][25][26]; a Mn form of ribonucleotide reductase (Mn-RNR) [27,28]; and, arguably the most recognized Mn-dependent enzyme, the photosynthetic core of green plants, algae, and certain cyanobacteria termed photosystem II (PSII) [29,30]. Through a series of photoinitiated electron transfer events, oxidizing equivalents are stored on the tetranuclear Mn core of PSII -the oxygen-evolving complex (OEC) -which then extracts four electrons (and four protons) from two substrate water molecules to yield molecular oxygen.…”

Section: Nih-pa Author Manuscriptmentioning

confidence: 99%

Multifrequency pulsed EPR studies of biologically relevant manganese(II) complexes

et al. 2007

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Electron paramagnetic resonance studies at multiple frequencies (MF EPR) can provide detailed electronic structure descriptions of unpaired electrons in organic radicals, inorganic complexes, and metalloenzymes. Analysis of these properties aids in the assignment of the chemical environment surrounding the paramagnet and provides mechanistic insight into the chemical reactions in which these systems take part. Herein, we present results from pulsed EPR studies performed at three different frequencies (9, 31, and 130 GHz) on [Mn(II)(H 2 O) 6 ] 2+ , Mn(II) adducts with the nucleotides ATP and GMP, and the Mn(II)-bound form of the hammerhead ribozyme (MnHH). Through line shape analysis and interpretation of the zero-field splitting values derived from successful simulations of the corresponding continuous-wave and field-swept echodetected spectra, these data are used to exemplify the ability of the MF EPR approach in distinguishing the nature of the first ligand sphere. A survey of recent results from pulsed EPR, as well as pulsed electron-nuclear double resonance and electron spin echo envelope modulation spectroscopic studies applied to Mn(II)-dependent systems, is also presented. Mn-Containing Biological SystemsManganese operates as a cofactor in numerous proteins, serving both catalytic and structural roles [1][2][3][4]. Many Mn-dependent enzymes take advantage o f the rich redox chemistry available to the metal, accessing the +2, +3, +4, and perhaps even the +5 oxidation states during their turnover. For example, Mn-superoxide dismutase (MnSOD), which detoxifies the cell of the superoxide radical , cycles between the Mn(II) and Mn(III) oxidation states via the ping-pong type mechanism shown below [5][6][7][8][9].(1a) (1b) Other examples of such mononuclear redox-active enzymes include the manganese peroxidase responsible for lignin degradation by white-rot fungus [10][11][12]; a unique Mndependent form of lipoxygenase [13][14][15][16]; oxalate decarboxylase [17,18]; as well as an extradiol catechol dioxygenase [19][20][21]. NIH-PA Author ManuscriptNIH-PA Author Manuscript NIH-PA Author ManuscriptIn order to help minimize kinetic and thermodynamic penalties associated with electron transfer events and the execution of chemical reactions, two or more metal centers can be coupled together to provide active sites capable of conducting multiple electrons while still operating within a physiologically accessible range of reduction potentials [22]. Only three such examples of redox-active polynuclear Mn enzymes are known: Mn-catalase that disproportionates hydrogen peroxide [23][24][25][26]; a Mn form of ribonucleotide reductase (Mn-RNR) [27,28]; and, arguably the most recognized Mn-dependent enzyme, the photosynthetic core of green plants, algae, and certain cyanobacteria termed photosystem II (PSII) [29,30]. Through a series of photoinitiated electron transfer events, oxidizing equivalents are stored on the tetranuclear Mn core of PSII -the oxygen-evolving complex (OEC) -which then extracts four electr...

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Section: Nih-pa Author Manuscriptmentioning

confidence: 99%

Multifrequency pulsed EPR studies of biologically relevant manganese(II) complexes

et al. 2007

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“…The reaction was started by adding T. brucei ribonucleotide reductase, and the assay mixture was incubated 20 min at 37°C. After dephosphorylation educts and products were separated by high performance liquid chromatography (19).…”

Section: Methodsmentioning

confidence: 99%

Identification and Functional Characterization of Thioredoxin from Trypanosoma brucei brucei

Reckenfelderbäumer

Lüdemann

Schmidt

et al. 2000

Journal of Biological Chemistry

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Trypanosomes and Leishmania, the causative agents of several tropical diseases, lack the glutathione/glutathione reductase system but have trypanothione/ trypanothione reductase instead. The uniqueness of this thiol metabolism and the failure to detect thioredoxin reductases in these parasites have led to the suggestion that these protozoa lack a thioredoxin system. As presented here, this is not the case. A gene encoding thioredoxin has been cloned from Trypanosoma brucei, the causative agent of African sleeping sickness. The single copy gene, which encodes a protein of 107 amino acid residues, is expressed in all developmental stages of the parasite. The deduced protein sequence is 56% identical with a putative thioredoxin revealed by the genome project of Leishmania major. The relationship to other thioredoxins is low. T. brucei thioredoxin is unusual in having a calculated pI value of 8.5. The gene has been overexpressed in Escherichia coli. The recombinant protein is a substrate of human thioredoxin reductase with a K m value of 6 M but is not reduced by trypanothione reductase. T. brucei thioredoxin catalyzes the reduction of insulin by dithioerythritol, and functions as an electron donor for T. brucei ribonucleotide reductase. The parasite protein is the first classical thioredoxin of the order Kinetoplastida characterized so far.

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“…This type of reductase has also been demonstrated in E. coil infected with bacteriophage T4, in green algae and in mammalian cells. Recently a manganese-containing ribonucleotide reductase has been isolated from Brevibacterium ammoniagenes and other coryneform bacteria and this enzyme probably also contains an organic radical [4]. Both these types of ribonucleotide reductases are inactivated by hydroxyurea or other hydroxylamine derivatives which reduce the organic radical.…”

Section: Introductionmentioning

confidence: 99%

Ribonucleotide reductase in cell extracts of Methanobacterium thermoautotrophicum

Hogenkamp¹,

Follmann²,

Thauer³

1987

FEBS Letters

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Cell free extracts of Methanobacterium thermoautrophicum were found to catalyze the reduction of CDP and GDP provided that the cells were harvested, disrupted and the extracts assayed under strictly anaerobic conditions. Ribonucleotide reduction is not affected by adenosylcobalamin and cell extracts do not catalyze the tritium exchange reaction between [5-3Hz]adenosylcobalamin and water. The reduction of CDP requires ATP and that of GDP requires dTTP as positive allosteric effectors. In contrast, dATP at low concentration stimulates CDP reduction while at higher concentrations it inhibits the reductase reaction.

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Ribonucleotide reductase of Brevibacterium ammoniagenes is a manganese enzyme

Cited by 175 publications

References 36 publications

Multifrequency pulsed EPR studies of biologically relevant manganese(II) complexes

Multifrequency pulsed EPR studies of biologically relevant manganese(II) complexes

Identification and Functional Characterization of Thioredoxin from Trypanosoma brucei brucei

Ribonucleotide reductase in cell extracts of Methanobacterium thermoautotrophicum

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