Abstract
Active beef heart aconitase contains an iron-sulfur cluster with an [Fe4S4]2+ core. This cluster can be converted into Fe3S4 with concomitant loss of enzymatic activity. We have reconstituted apo-aconitase with iron and selenide to obtain Fe4Se4 aconitase. The Se analog has higher catalytic activity than the native S-containing enzyme when isocitrate is the substrate. Oxidation of [Fe4Se4]2+ with ferricyanide yields the inactive [Fe3Se4]1+ form. The Se-containing 3-Fe cluster can be reduced to [Fe3Se4]0. We have studied the [Fe3S4]1+,0, [Fe3Se4]1+,0, and [Fe4Se4]2+ states with Mössbauer spectroscopy from 1.3 K to 200 K in magnetic fields up to 6.0 T. The spectra of the S- and Se-containing enzymes were found to be remarkably similar. The spectra of the 3-Fe clusters were analyzed and the salient features of the electronic structure are discussed.
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Selected References
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- Day E. P., Peterson J., Bonvoisin J. J., Moura I., Moura J. J. Magnetization of the oxidized and reduced three-iron cluster of Desulfovibrio gigas ferredoxin II. J Biol Chem. 1988 Mar 15;263(8):3684–3689. [PubMed] [Google Scholar]
- Emptage M. H., Kent T. A., Huynh B. H., Rawlings J., Orme-Johnson W. H., Münck E. On the nature of the iron-sulfur centers in a ferredoxin from Azotobacter vinelandii. Mössbauer studies and cluster displacement experiments. J Biol Chem. 1980 Mar 10;255(5):1793–1796. [PubMed] [Google Scholar]
- Emptage M. H., Kent T. A., Kennedy M. C., Beinert H., Münck E. Mössbauer and EPR studies of activated aconitase: development of a localized valence state at a subsite of the [4Fe-4S] cluster on binding of citrate. Proc Natl Acad Sci U S A. 1983 Aug;80(15):4674–4678. doi: 10.1073/pnas.80.15.4674. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Huynh B. H., Moura J. J., Moura I., Kent T. A., LeGall J., Xavier A. V., Münck E. Evidence for a three-iron center in a ferredoxin from Desulfovibrio gigas. Mössbauer and EPR studies. J Biol Chem. 1980 Apr 25;255(8):3242–3244. [PubMed] [Google Scholar]
- Kennedy M. C., Beinert H. The state of cluster SH and S2- of aconitase during cluster interconversions and removal. A convenient preparation of apoenzyme. J Biol Chem. 1988 Jun 15;263(17):8194–8198. [PubMed] [Google Scholar]
- Kennedy M. C., Emptage M. H., Dreyer J. L., Beinert H. The role of iron in the activation-inactivation of aconitase. J Biol Chem. 1983 Sep 25;258(18):11098–11105. [PubMed] [Google Scholar]
- Kennedy M. C., Kent T. A., Emptage M., Merkle H., Beinert H., Münck E. Evidence for the formation of a linear [3Fe-4S] cluster in partially unfolded aconitase. J Biol Chem. 1984 Dec 10;259(23):14463–14471. [PubMed] [Google Scholar]
- Kent T. A., Dreyer J. L., Kennedy M. C., Huynh B. H., Emptage M. H., Beinert H., Münck E. Mössbauer studies of beef heart aconitase: evidence for facile interconversions of iron-sulfur clusters. Proc Natl Acad Sci U S A. 1982 Feb;79(4):1096–1100. doi: 10.1073/pnas.79.4.1096. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Kent T. A., Emptage M. H., Merkle H., Kennedy M. C., Beinert H., Münck E. Mössbauer studies of aconitase. Substrate and inhibitor binding, reaction intermediates, and hyperfine interactions of reduced 3Fe and 4Fe clusters. J Biol Chem. 1985 Jun 10;260(11):6871–6881. [PubMed] [Google Scholar]
- Kent T. A., Huynh B. H., Münck E. Iron-sulfur proteins: spin-coupling model for three-iron clusters. Proc Natl Acad Sci U S A. 1980 Nov;77(11):6574–6576. doi: 10.1073/pnas.77.11.6574. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Moulis J. M., Auric P., Gaillard J., Meyer J. Unusual features in EPR and Mössbauer spectra of the 2[4Fe-4Se]+ ferredoxin from Clostridium pasteurianum. J Biol Chem. 1984 Sep 25;259(18):11396–11402. [PubMed] [Google Scholar]
- Moulis J. M., Meyer J. Characterization of the selenium-substituted 2 [4Fe-4Se] ferredoxin from Clostridium pasteurianum. Biochemistry. 1982 Sep 14;21(19):4762–4771. doi: 10.1021/bi00262a037. [DOI] [PubMed] [Google Scholar]
- Münck E., Debrunner P. G., Tsibris J. C., Gunsalus I. C. Mössbauer parameters of putidaredoxin and its selenium analog. Biochemistry. 1972 Feb 29;11(5):855–863. doi: 10.1021/bi00755a027. [DOI] [PubMed] [Google Scholar]
- Robbins A. H., Stout C. D. Structure of activated aconitase: formation of the [4Fe-4S] cluster in the crystal. Proc Natl Acad Sci U S A. 1989 May;86(10):3639–3643. doi: 10.1073/pnas.86.10.3639. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Wood J. L. Sulfane sulfur. Methods Enzymol. 1987;143:25–29. doi: 10.1016/0076-6879(87)43009-7. [DOI] [PubMed] [Google Scholar]
