EXAFS studies of binuclear iron proteins: hemerythrin and ribonucleotide reductase

Scarrow, Robert C.; Maroney, Michael J.; Palmer, Sharon M.; Que, Lawrence; Roe, A. L.; Salowe, Scott P.; Stubbe, Jo Anne

doi:10.1021/ja00259a039

Cited by 100 publications

(108 citation statements)

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“…This 3.44-Å distance is close to the FeϪFe distances found in the iron(II)iron(III) sites of photoreduced MMOH (35), uteroferrin (38), and semimetHrN 3 (39). EXAFS analysis thus further corroborates the diiron nature of the active site of hDOHH phr .…”

Section: Table 1 Properties Of Diiron(iii)-peroxo Units In Enzymes Asupporting

confidence: 73%

Human deoxyhypusine hydroxylase, an enzyme involved in regulating cell growth, activates O ₂ with a nonheme diiron center

Emerson

Martinho

et al. 2009

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

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Deoxyhypusine hydroxylase is the key enzyme in the biosynthesis of hypusine containing eukaryotic translation initiation factor 5A (eIF5A), which plays an essential role in the regulation of cell proliferation. Recombinant human deoxyhypusine hydroxylase (hDOHH) has been reported to have oxygen-and iron-dependent activity, an estimated iron/holoprotein stoichiometry of 2, and a visible band at 630 nm responsible for the blue color of the as-isolated protein. EPR, Mö ssbauer, and XAS spectroscopic results presented herein provide direct spectroscopic evidence that hDOHH has an antiferromagnetically coupled diiron center with histidines and carboxylates as likely ligands, as suggested by mutagenesis experiments. Resonance Raman experiments show that its blue chromophore arises from a ( -1,2-peroxo)diiron(III) center that forms in the reaction of the reduced enzyme with O 2, so the peroxo form of hDOHH is unusually stable. Nevertheless we demonstrate that it can carry out the hydroxylation of the deoxyhypusine residue present in the elF5A substrate. Despite a lack of sequence similarity, hDOHH has a nonheme diiron active site that resembles both in structure and function those found in methane and toluene monooxygenases, bacterial and mammalian ribonucleotide reductases, and stearoyl acyl carrier protein ⌬ 9 -desaturase from plants, suggesting that the oxygen-activating diiron motif is a solution arrived at by convergent evolution. Notably, hDOHH is the only example thus far of a human hydroxylase with such a diiron active site.H ypusine is an unusual, but highly conserved, amino acid that is found only in the eukaryotic translational initiation factor 5A (eIF5A), a protein that regulates cell proliferation (1, 2). The biosynthesis of eIF5A involves a posttranslational modification of the eIF5A precursor, where a lysine residue is first modified to deoxyhypusine (Dhp) by deoxyhypusine synthase (DHS) and then the nascent Dhp is hydroxylated by deoxyhypusine hydroxylase (DOHH) to form hypusine (Hpu) (Scheme 1) (1, 2). The importance of hypusine and these 2 enzymes has been shown by several studies where depletion of spermidine (3) or inhibition of either DHS or DOHH (4, 5) leads to a decrease of hypusinecontaining eIF5A [eIF5A(Hpu)] and inhibition of eukaryotic cell growth. Consequently, these results suggest that eIF5A and DOHH could be promising targets for antitumor (6) and anti-HIV-1 therapies (7).The hydroxylase activity of recombinant human DOHH (hDOHH) has been shown to depend on Fe(II) and not on any other physiologically relevant divalent metal ion. An estimated iron-to-holoprotein stoichiometry of 2 is observed (8). Sequence examination, homology modeling, and mutagenesis experiments suggest 2 possible iron binding sites consisting of histidine and carboxylate ligands (8,9). Thus at first glance, hDOHH appears to resemble members of the superfamily of bacterial diiron multicomponent monooxygenases, like methane or toluene monooxygenase, that use nonheme diiron centers to activate dioxygen for the hydroxylat...

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Section: Table 1 Properties Of Diiron(iii)-peroxo Units In Enzymes Asupporting

confidence: 73%

Human deoxyhypusine hydroxylase, an enzyme involved in regulating cell growth, activates O ₂ with a nonheme diiron center

Emerson

Martinho

et al. 2009

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

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107

141

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“…X-ray absorption spectra at the iron K-edge were collected between 6.9 and 8.0 keV, and the monochromator was calibrated by using the edge energy of iron foil at 7,112.0 eV. The data were obtained in fluorescence mode [A exp (C f ͞C 0 )] at 13(1) K. Our XAS data analysis protocol has been described (26). (24).…”

Section: Methodsmentioning

confidence: 99%

An Fe ^IV O complex of a tetradentate tripodal nonheme ligand

Lim

Rohde

Stubna

et al. 2003

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

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“…43,44 A modification of the EXAPLT program was employed to extract from A exp by using a cubic spline function, including preliminary baseline correction and correction of fluorescence data for thickness effects and detector response. 41 The refinements reported were on k 3 data, and the function minimized was R ) {∑k 6 ( c -) 2 /N} 1/2 , where the sum is over N data points within the selected k space. The fitting results indicate the average metal-ligand distances, the type and the number of scatterers, and the Debye-Waller factors which can be used to evaluate the distribution of Fe-ligand bond lengths in each shell.…”

Section: N-methyl-nn′n′-tris(2-mentioning

confidence: 99%

End-On and Side-On Peroxo Derivatives of Non-Heme Iron Complexes with Pentadentate Ligands: Models for Putative Intermediates in Biological Iron/Dioxygen Chemistry

et al. 2003

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Mononuclear iron(III) species with end-on and side-on peroxide have been proposed or identified in the catalytic cycles of the antitumor drug bleomycin and a variety of enzymes, such as cytochrome P450 and Rieske dioxygenases. Only recently have biomimetic analogues of such reactive species been generated and characterized at low temperatures. We report the synthesis and characterization of a series of iron(II) complexes with pentadentate N5 ligands that react with H 2 O 2 to generate transient low-spin Fe III −OOH intermediates. These intermediates have low-spin iron(III) centers exhibiting hydroperoxo-to-iron(III) charge-transfer bands in the 500−600-nm region. Their resonance Raman frequencies, ν O-O , near 800 cm -1 are significantly lower than those observed for high-spin counterparts. The hydroperoxo-to-iron(III) charge-transfer transition blue-shifts and the ν O-O of the Fe−OOH unit decreases as the N5 ligand becomes more electron donating. Thus, increasing electron density at the low-spin Mononuclear iron(III) peroxide species are implicated as intermediates in the mechanisms of oxygen activating biomolecules such as cytochrome P450, 1 heme oxygenase, 2 the antitumor drug bleomycin, 3 and Rieske dioxygenases, 4,5 as well as superoxide reductases from anaerobic bacteria. [6][7][8][9] Experimental evidence for some of these intermediates has

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EXAFS studies of binuclear iron proteins: hemerythrin and ribonucleotide reductase

Cited by 100 publications

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Human deoxyhypusine hydroxylase, an enzyme involved in regulating cell growth, activates O ₂ with a nonheme diiron center

Human deoxyhypusine hydroxylase, an enzyme involved in regulating cell growth, activates O ₂ with a nonheme diiron center

An Fe ^IV O complex of a tetradentate tripodal nonheme ligand

End-On and Side-On Peroxo Derivatives of Non-Heme Iron Complexes with Pentadentate Ligands: Models for Putative Intermediates in Biological Iron/Dioxygen Chemistry

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EXAFS studies of binuclear iron proteins: hemerythrin and ribonucleotide reductase

Cited by 100 publications

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Human deoxyhypusine hydroxylase, an enzyme involved in regulating cell growth, activates O 2 with a nonheme diiron center

Human deoxyhypusine hydroxylase, an enzyme involved in regulating cell growth, activates O 2 with a nonheme diiron center

An Fe IV O complex of a tetradentate tripodal nonheme ligand

End-On and Side-On Peroxo Derivatives of Non-Heme Iron Complexes with Pentadentate Ligands: Models for Putative Intermediates in Biological Iron/Dioxygen Chemistry

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Human deoxyhypusine hydroxylase, an enzyme involved in regulating cell growth, activates O ₂ with a nonheme diiron center

Human deoxyhypusine hydroxylase, an enzyme involved in regulating cell growth, activates O ₂ with a nonheme diiron center

An Fe ^IV O complex of a tetradentate tripodal nonheme ligand