Disease relevance of thioxoiron

• The spectroscopic properties of Fe-SoxR indicated that it contains a redox active iron-sulfur (FeS) cluster that is oxidized upon extraction from E. coli [1].
• Crystal structure of the cystine C-S lyase from Synechocystis: stabilization of cysteine persulfide for FeS cluster biosynthesis [2].
• Putative binding elements for the primary donor, P840 in Chlorobium and P700 in PS1, and for the acceptors A0, A1, and FeS center X are conserved [3].
• Previous studies on the enzyme from Vibrio alginolyticus have shown that the Na(+)-NQR has six subunits, and it is known to contain FAD and an FeS center as redox cofactors [4].
• A dimer of the FeS cluster biosynthesis protein IscA from cyanobacteria binds a [2Fe2S] cluster between two protomers and transfers it to [2Fe2S] and [4Fe4S] apo proteins [5].

Psychiatry related information on thioxoiron

• The steps of electron-transfer scheme, menaquinol --> Rieske FeS center --> cytochrom c-556 --> cytochrome cz --> P840, are estimated to have reaction times of 20 ms and 560, 150, and 40 microseconds, respectively [6].

High impact information on thioxoiron

• The variable redox state of the SoxR FeS cluster may thus be employed in vivo to modulate the transcriptional activity of this protein in response to specific types of oxidative stress [1].
• These results indicate that mitochondrial FeS cluster assembly is indispensable for completion of the T. brucei life cycle [7].
• However, nothing is known about FeS cluster biogenesis in trypanosomes, organisms that are evolutionarily distant from yeast and humans [7].
• The SAM-binding site of AtsB involves (83)GGE(85) and possibly also a juxtaposed FeS center coordinated by Cys(39) and Cys(42), as indicated by alanine scanning mutagenesis [8].
• Here, we report that the redox reaction of the FeS cluster N2 located on subunit NuoB of the Escherichia coli complex I induces a protonation/deprotonation of tyrosine side chains [9].

Chemical compound and disease context of thioxoiron

• FT-IR spectroscopic characterization of NADH:ubiquinone oxidoreductase (complex I) from Escherichia coli: oxidation of FeS cluster N2 is coupled with the protonation of an aspartate or glutamate side chain [10].
• A Thiobacillus denitrificans-like bacterium was present in an enrichment on thiosulfate and nitrate, derived from an iron-sulfide- and nitrate-rich freshwater environment [11].
• In sediments that contain iron monosulfide, cadmium, nickel, lead, zinc, and silver(I) form insoluble metal sulfides that lower the metal ion activity in the sediment-pore water system, thereby reducing toxicity [12].

Biological context of thioxoiron

• The terminal segment of the aerobic respiratory chain of the thermoacidophilic archaeon Sulfolobus sp. strain 7 is an unusual caldariellaquinol oxidase supercomplex, which contains at least one b-type and three spectroscopically distinguishable a-type cytochromes, one copper, and a Rieske-type FeS center [13].
• The phylogeny indicates the presence of a common mechanism for FeS cluster formation in mitochondriates as well as in amitochondriate eukaryotes [14].
• Although FeS proteins are particularly important for the energy metabolism of amitochondrial anaerobic eukaryotes, there is no information about FeS cluster formation in these organisms [14].
• The combined results strongly indicate that the FeS cluster of the CFeSP is necessary for reductive activation of Co(II) to Co(I) by physiological reductants but is not required for catalysis, e.g., demethylation of CH3-H4folate or methylation of CODH/ACS [15].
• Computer analysis showed that the MauG polypeptide contains two putative heme binding sites and that the MauM and MauN polypeptides have four and two FeS cluster signatures, respectively [16].

Anatomical context of thioxoiron

• Employing an assay that allowed us to monitor the conversion of the apoform of mitochondrial ferredoxin into its FeS-containing holoform, Ssq1 was demonstrated to be required for the FeS cluster assembly in mitochondria [17].

Associations of thioxoiron with other chemical compounds

• Mutant FeS4 (C451S, D442C) also contained an FeS cluster and was processed; the enzyme had about 50% of wild type-specific activity and reacted with O2 in vitro at the same rate as the wild type [18].
• Mössbauer spectroscopy further indicated that the FeS cluster was bound by four cysteine residues [5].
• The theoretical interpretation of this dependence suggests that the troilite oxidation involves several processes: Both experimental results and theoretical considerations illustrate the importance of temperature, pH, and [H(2)O(2)] for the kinetics and mechanisms of troilite oxidation [19].
• Isotope dilution mass spectrometry is an ideal analytical technique to measure the elemental abundance of Mo in C1 carbonaceous chondrites and the metallic and troilite phases of iron meteorites [20].

Gene context of thioxoiron

• No constitutive mutation was found within the region encoding the cysteines of the SoxR FeS center, in the soxR or soxS promoters, or in the soxS structural gene [21].
• By EPR spectroscopy, a signal of a single reduced FeS cluster was found in a crystal of reduced FDH, but not in a crystal of oxidized enzyme, whereas Mo(V) signal was not detected in either form of crystalline FDH [22].
• We propose that, during reductive activation, electrons flow from the reduced electron-transfer protein (e.g., CODH/ACS or reduced ferredoxin (Fd)) to the FeS cluster which then directs electrons to the cobalt center for catalysis [15].
• Additional signals in the spectra of complex I reflect contributions induced by the redox transition of the high-potential FeS cluster N2 which is not present in the NADH dehydrogenase fragment [10].
• Whether sulredoxin is derived from the archaeal membrane-bound respiratory Rieske-type FeS center (gy = 1.91) is the subject of further investigation [23].

Analytical, diagnostic and therapeutic context of thioxoiron

• Four mutants of amidotransferases that alter cysteinyl ligands to the FeS cluster or residues adjacent to them have been prepared by site-directed mutagenesis, expressed in Escherichia coli, and characterized (Makaroff, C. A., Paluh, J. L., and Zalkin, H. (1986) J. Biol. Chem. 261, 11416-11423) [18].
• We describe an in vitro assay system that allows for real-time monitoring of [FeS] cluster formation using circular dichroism spectroscopy and use this to investigate de novo [FeS] cluster formation and transfer from Escherichia coli IscU and IscA to apo-ferredoxin [24].

References