Journal articles: 'Iron sulphur proteins'

1

DING, Huangen, and Robert J. CLARK. "Characterization of iron binding in IscA, an ancient iron-sulphur cluster assembly protein." Biochemical Journal 379, no. 2 (April 15, 2004): 433–40. http://dx.doi.org/10.1042/bj20031702.

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Iron–sulphur clusters are one of the most common types of redox centre in biology. At least six proteins (IscS, IscU, IscA, HscB, HscA and ferredoxin) have been identified as being essential for the biogenesis of iron–sulphur proteins in bacteria. It has been shown that IscS is a cysteine desulphurase that provides sulphur for iron–sulphur clusters, and that IscU is a scaffold for the IscS-mediated assembly of iron–sulphur clusters. The iron donor for iron–sulphur clusters, however, remains elusive. Here we show that IscA is an iron binding protein with an apparent iron association constant of 3.0×1019 M−1, and that iron-loaded IscA can provide iron for the assembly of transient iron–sulphur clusters in IscU in the presence of IscS and l-cysteine in vitro. The results suggest that IscA is capable of recruiting intracellular iron and delivering iron for iron–sulphur clusters in proteins.

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2

Lill, Roland. "Function and biogenesis of iron–sulphur proteins." Nature 460, no. 7257 (August 2009): 831–38. http://dx.doi.org/10.1038/nature08301.

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3

Seidler, A., K. Jaschkowitz, and M. Wollenberg. "Incorporation of iron-sulphur clusters in membrane-bound proteins." Biochemical Society Transactions 29, no. 4 (August 1, 2001): 418–21. http://dx.doi.org/10.1042/bst0290418.

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The completely sequenced genome of the cyano-bacterium Synechocystis PCC 6803 contains several open reading frames, of which the deduced amino acid sequences show similarities to proteins known to be involved in FeS cluster synthesis of nitrogenase (Nif proteins) and other FeS proteins (Isc proteins). In this article, the results of our studies on these proteins are summarized and discussed with respect to their relevance in FeS cluster incorporation in chloroplasts. In cyanobacteria, there appears to exist several pathways for FeS cluster synthesis.

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Seidler, A., K. Jaschkowitz, and M. Wollenberg. "Incorporation of iron-sulphur clusters into membrane-bound proteins." Biochemical Society Transactions 29, no. 3 (June 1, 2001): A51. http://dx.doi.org/10.1042/bst029a051a.

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Goldberg, Alina V., Sabine Molik, Anastasios D. Tsaousis, Karina Neumann, Grit Kuhnke, Frederic Delbac, Christian P. Vivares, Robert P. Hirt, Roland Lill, and T. Martin Embley. "Localization and functionality of microsporidian iron–sulphur cluster assembly proteins." Nature 452, no. 7187 (March 2, 2008): 624–28. http://dx.doi.org/10.1038/nature06606.

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6

Rouault, Tracey A. "Mammalian iron–sulphur proteins: novel insights into biogenesis and function." Nature Reviews Molecular Cell Biology 16, no. 1 (November 26, 2014): 45–55. http://dx.doi.org/10.1038/nrm3909.

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7

Sundararajan, M., J. P. McNamara, M. Mohr, I. H. Hillier, and H. Wang. "A semi-empirical molecular orbital scheme to study electron transfer in iron–sulphur proteins." Biochemical Society Transactions 33, no. 1 (February 1, 2005): 20–21. http://dx.doi.org/10.1042/bst0330020.

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We describe the use of the semi-empirical molecular orbital method PM3 (parametric method 3) to study the electronic structure of iron–sulphur proteins. We first develop appropriate parameters to describe models of the redox site of rubredoxins, followed by some preliminary calculations of multinuclear iron systems of relevance to hydrogenases.

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Frazzon, J., J. R. Fick, and D. R. Dean. "Biosynthesis of iron-sulphur clusters is a complex and highly conserved process." Biochemical Society Transactions 30, no. 4 (August 1, 2002): 680–85. http://dx.doi.org/10.1042/bst0300680.

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Iron-sulphur ([Fe-S]) clusters are simple inorganic prosthetic groups that are contained in a variety of proteins having functions related to electron transfer, gene regulation, environmental sensing and substrate activation. In spite of their simple structures, biological [Fe-S] clusters are not formed spontaneously. Rather, a consortium of highly conserved proteins is required for both the formation of [Fe-S] clusters and their insertion into various protein partners. Among the [Fe-S] cluster biosynthetic proteins are included a pyridoxal phosphate-dependent enzyme (NifS) that is involved in the activation of sulphur from L-cysteine, and a molecular scaffold protein (NifU) upon which [Fe-S] cluster precursors are formed. The formation or transfer of [Fe-S] clusters appears to require an electron-transfer step. Another complexity is that molecular chaperones homologous to DnaJ and DnaK are involved in some aspect of the maturation of [Fe-S]-cluster-containing proteins. It appears that the basic biochemical features of [Fe-S] cluster formation are strongly conserved in Nature, since organisms from all three life Kingdoms contain the same consortium of homologous proteins required for [Fe-S] cluster formation that were discovered in the eubacteria.

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9

Armstrong, Fraser A. "Voltammetric studies of the reactions of iron-sulphur centers in proteins." Journal of Inorganic Biochemistry 43, no. 2-3 (August 1991): 238. http://dx.doi.org/10.1016/0162-0134(91)84228-2.

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10

Degli Esposti, M., F. Ballester, G. Solaini, and G. Lenaz. "The circular-dichroic properties of the ‘Rieske’ iron-sulphur protein in the mitochondrial ubiquinol: cytochrome c reductase." Biochemical Journal 241, no. 1 (January 1, 1987): 285–90. http://dx.doi.org/10.1042/bj2410285.

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We have studied the c.d. spectra of the ‘Rieske’ iron-sulphur protein isolated from the ubiquinol: cytochrome c reductase (bc1 complex) of bovine heart mitochondria. Both the oxidized and the reduced form of the ‘Rieske’ protein display a series of well-resolved c.d. features resembling those reported for the ‘Rieske’-type iron-sulphur protein purified from the bacterium Thermus thermophilus [Fee, Findling, Yoshida, Hille, Tarr, Hearshen, Dunham, Day, Kent & Münck (1984) J. Biol, Chem. 259, 124-133]. In particular, the difference spectra, reduced minus oxidized, of both proteins have a distinctive negative band at 497 nm. The c.d. features characteristic of the isolated ‘Rieske’ protein were found in the dichroic spectra of the whole bc1 complex in the region between 450 and 520 nm. The reduction of the enzyme by ascorbate or ubiquinol is accompanied by the formation of a negative band at about 500 nm that corresponds, in all its c.d. properties, to the specific dichroic absorption of the reduced ‘Rieske’ iron-sulphur protein.

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11

Armstrong, Fraser A., and Robert J. P. Williams. "Thermodynamic influences on the fidelity of iron-sulphur cluster formation in proteins." FEBS Letters 451, no. 2 (May 21, 1999): 91–94. http://dx.doi.org/10.1016/s0014-5793(99)00545-1.

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12

Vilella, Felipe, Rui Alves, María Teresa Rodríguez-Manzaneque, Gemma Bellí, Swarna Swaminathan, Per Sunnerhagen, and Enrique Herrero. "Evolution and Cellular Function of Monothiol Glutaredoxins: Involvement in Iron-Sulphur Cluster Assembly." Comparative and Functional Genomics 5, no. 4 (2004): 328–41. http://dx.doi.org/10.1002/cfg.406.

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A number of bacterial species, mostly proteobacteria, possess monothiol glutaredoxins homologous to theSaccharomyces cerevisiaemitochondrial protein Grx5, which is involved in iron–sulphur cluster synthesis. Phylogenetic profiling is used to predict that bacterial monothiol glutaredoxins also participate in the iron–sulphur cluster (ISC) assembly machinery, because their phylogenetic profiles are similar to the profiles of the bacterial homologues of yeast ISC proteins. High evolutionary co-occurrence is observed between the Grx5 homologues and the homologues of the Yah1 ferredoxin, the scaffold proteins Isa1 and Isa2, the frataxin protein Yfh1 and the Nfu1 protein. This suggests that a specific functional interaction exists between these ISC machinery proteins. Physical interaction analyses using low-definition protein docking predict the formation of strong and specific complexes between Grx5 and several components of the yeast ISC machinery. Two-hybrid analysis has confirmed thein vivointeraction between Grx5 and Isa1. Sequence comparison techniques and cladistics indicate that the other two monothiol glutaredoxins ofS. cerevisiae, Grx3 and Grx4, have evolved from the fusion of a thioredoxin gene with a monothiol glutaredoxin gene early in the eukaryotic lineage, leading to differential functional specialization. While bacteria do not contain these chimaeric glutaredoxins, in many eukaryotic species Grx5 and Grx3/4-type monothiol glutaredoxins coexist in the cell.

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13

Butler, Anthony R., Christopher Glidewell, Andrew R. Hyde, and John C. Walton. "Nitrosylation of 2Fe-2S and 4Fe-4S models for iron-sulphur redox proteins." Inorganica Chimica Acta 106, no. 2 (February 1985): L7—L8. http://dx.doi.org/10.1016/s0020-1693(00)82246-x.

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14

ŠIMKOVIČ, Martin, Gregory D. DEGALA, Sandra S. EATON, and Frank E. FRERMAN. "Expression of human electron transfer flavoprotein-ubiquinone oxidoreductase from a baculovirus vector: kinetic and spectral characterization of the human protein." Biochemical Journal 364, no. 3 (June 15, 2002): 659–67. http://dx.doi.org/10.1042/bj20020042.

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Electron transfer flavoprotein-ubiquinone oxidoreductase (ETF-QO) is an iron—sulphur flavoprotein and a component of an electron-transfer system that links 10 different mitochondrial flavoprotein dehydrogenases to the mitochondrial bc1 complex via electron transfer flavoprotein (ETF) and ubiquinone. ETF-QO is an integral membrane protein, and the primary sequences of human and porcine ETF-QO were deduced from the sequences of the cloned cDNAs. We have expressed human ETF-QO in Sf9 insect cells using a baculovirus vector. The cDNA encoding the entire protein, including the mitochondrial targeting sequence, was present in the vector. We isolated a membrane-bound form of the enzyme that has a molecular mass identical with that of the mature porcine protein as determined by SDS/PAGE and has an N-terminal sequence that is identical with that predicted for the mature holoenzyme. These data suggest that the heterologously expressed ETF-QO is targeted to mitochondria and processed to the mature, catalytically active form. The detergent-solubilized protein was purified by ion-exchange and hydroxyapatite chromatography. Absorption and EPR spectroscopy and redox titrations are consistent with the presence of flavin and iron—sulphur centres that are very similar to those in the equivalent porcine and bovine proteins. Additionally, the redox potentials of the two prosthetic groups appear similar to those of the other eukaryotic ETF-QO proteins. The steady-state kinetic constants of human ETF-QO were determined with ubiquinone homologues, a ubiquinone analogue, and with human wild-type ETF and a Paracoccus—human chimaeric ETF as varied substrates. The results demonstrate that this expression system provides sufficient amounts of human ETF-QO to enable crystallization and mechanistic investigations of the iron—sulphur flavoprotein.

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15

LÉON, Sébastien, Brigitte TOURAINE, Cécile RIBOT, Jean-François BRIAT, and Stéphane LOBÉRAUX. "Iron-sulphur cluster assembly in plants: distinct NFU proteins in mitochondria and plastids from Arabidopsis thaliana." Biochemical Journal 371, no. 3 (May 1, 2003): 823–30. http://dx.doi.org/10.1042/bj20021946.

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Recent results are in favour of a role for NFU-like proteins in Fe–S cluster biogenesis. These polypeptides share a conserved CXXC motif in their NFU domain. In the present study, we have characterized Arabidopsis thalianaNFU1–5 genes. AtNFU proteins are separated into two classes. NFU4 and NFU5 are part of the mitochondrial type, presenting a structural organization similar to Saccharomyces cerevisiae Nfu1p. These proteins complement a Δisu1Δnfu1 yeast mutant and NFU4 mitochondrial localization was confirmed by green fluorescent protein fusion analysis. AtNFU1–3 represent a new class of NFU proteins, unique to plants. These polypeptides are made of two NFU domains, the second having lost its CXXC motif. AtNFU1–3 proteins are more related to Synechocystis PCC6803 NFU-like proteins and are localized to plastids when fused with the green fluorescent protein. NFU2 and/or NFU3 were detected in leaf chloroplasts by immunoblotting. NFU1 and NFU2 are functional NFU capable of restoring the growth of a Δisu1Δnfu1 yeast mutant, when addressed to yeast mitochondria. Furthermore, NFU2 recombinant protein is capable of binding a labile 2Fe–2S cluster in vitro. These results demonstrate the presence of distinct NFU proteins in Arabidopsis mitochondria and plastids. Such results suggest the existence of two different Fe–S assembly machineries in plant cells.

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16

TILLEY, Gareth J., Raul CAMBA, Barbara K. BURGESS, and Fraser A. ARMSTRONG. "Influence of electrochemical properties in determining the sensitivity of [4Fe-4S] clusters in proteins to oxidative damage." Biochemical Journal 360, no. 3 (December 10, 2001): 717–26. http://dx.doi.org/10.1042/bj3600717.

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Interconversion between [4Fe-4S] cubane and [3Fe-4S] cuboidal states represents one of the simplest structural changes an iron–sulphur cluster can undertake. This reaction is implicated in oxidative damage and in modulation of the activity and regulation of certain enzymes, and it is therefore important to understand the factors governing cluster stability and the processes that activate cluster conversion. In the present study, protein film voltammetry has been used to induce and monitor the oxidative conversion of [4Fe-4S] into [3Fe-4S] clusters in different variants of Azotobacter vinelandii ferredoxin I (AvFdI; the 8Fe form of the native protein), and ΔThr14/ΔAsp15, Thr14 → Cys (T14C) and C42D mutants. The electrochemical results have been correlated with the differing oxygen sensitivities of [4Fe-4S] clusters, and comparisons have been drawn with other ferredoxins (Desulfovibrio africanus FdIII, Clostridium pasteurianum Fd, Thauera aromatica Fd and Pyrococcus furiosus Fd). In contrast with high-potential iron–sulphur proteins (HiPIPs) for which the oxidized species [4Fe-4S]3+ is inert to degradation and can be isolated, the hypervalent state in these ferredoxins (most obviously the 3+ level) is very labile, and the reduction potential at which this is formed is a key factor in determining the cluster's resistance to oxidative damage.

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17

Waller, Jeffrey C., Kenneth W. Ellens, Sophie Alvarez, Karen Loizeau, Stéphane Ravanel, and Andrew D. Hanson. "Mitochondrial and plastidial COG0354 proteins have folate-dependent functions in iron–sulphur cluster metabolism." Journal of Experimental Botany 63, no. 1 (October 6, 2011): 403–11. http://dx.doi.org/10.1093/jxb/err286.

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18

Bastow, Emma L., Katrine Bych, Jason C. Crack, Nick E. Le Brun, and Janneke Balk. "NBP35 interacts with DRE2 in the maturation of cytosolic iron-sulphur proteins inArabidopsis thaliana." Plant Journal 89, no. 3 (February 2017): 590–600. http://dx.doi.org/10.1111/tpj.13409.

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19

Uhrigshardt, H., S. Zoske, and S. Anemüller. "Sulfolobus aconitase, a regulator of iron metabolism?" Biochemical Society Transactions 30, no. 4 (August 1, 2002): 685–87. http://dx.doi.org/10.1042/bst0300685.

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The aconitase of Sulfolobus solfataricus, a hyperthermophilic crenarchaeon, was cloned and heterologously expressed in Escherichia coli. Enzymic analyses and EPR measurements indicated clearly that the iron-sulphur cluster of the thermophilic aconitase was already inserted in the mesophilic host. The enzyme was purified to a specific activity of approx.44 units/mg and to 90% homogeneity. The enzymic parameters of the recombinant aconitase turned out to be in the same range as the respective values for the previously characterized native enzyme from the closely related S. acidocaldarius. Based on its primary sequence, the recombinant aconitase is closely related to bacterial A-like and to eukaryotic iron regulatory protein-like proteins. Specific aconitase activities in cytosolic extracts of S. acidocaldarius were found to be decreased markedly in iron-starved compared with iron-repleted cells. However, no differences in aconitase levels between iron-starved and iron-supplemented cells could be detected by immunostaining.

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20

Thomsen, C., J. Gurgel-Giannetti, Y. Sunnerhagen, A. Giannetti, F. Kok, M. Vainzof, and A. Oldfors. "P.54Defects in iron-sulphur cluster assembly proteins ISCU and FDX2 cause characteristic mitochondrial myopathy." Neuromuscular Disorders 29 (October 2019): S56—S57. http://dx.doi.org/10.1016/j.nmd.2019.06.083.

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21

Seemann, Myriam, and Michel Rohmer. "Isoprenoid biosynthesis via the methylerythritol phosphate pathway: GcpE and LytB, two novel iron–sulphur proteins." Comptes Rendus Chimie 10, no. 8 (August 2007): 748–55. http://dx.doi.org/10.1016/j.crci.2007.01.016.

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22

Balk, Janneke, Antonio J. Pierik, Daili J. Aguilar Netz, Ulrich Mühlenhoff, and Roland Lill. "The hydrogenase-like Nar1p is essential for maturation of cytosolic and nuclear iron–sulphur proteins." EMBO Journal 23, no. 10 (April 22, 2004): 2105–15. http://dx.doi.org/10.1038/sj.emboj.7600216.

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23

Kumar, Bijay, Sushma Chaubey, Priyanka Shah, Aiman Tanveer, Manish Charan, Mohammad Imran Siddiqi, and Saman Habib. "Interaction between sulphur mobilisation proteins SufB and SufC: Evidence for an iron–sulphur cluster biogenesis pathway in the apicoplast of Plasmodium falciparum." International Journal for Parasitology 41, no. 9 (August 2011): 991–99. http://dx.doi.org/10.1016/j.ijpara.2011.05.006.

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24

MOIR, James W. B., Josa-Marie WEHRFRITZ, Stephen SPIRO, and David J. RICHARDSON. "The biochemical characterization of a novel non-haem-iron hydroxylamine oxidase from Paracoccus denitrificans GB17." Biochemical Journal 319, no. 3 (November 1, 1996): 823–27. http://dx.doi.org/10.1042/bj3190823.

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The characterization of the hydroxylamine oxidase from the heterotrophic nitrifier Paracoccus denitrificans GB17 indicates the enzyme to be entirely distinct from the hydroxylamine oxidase from the autotrophic nitrifier Nitrosomonas europaea. Hydroxylamine oxidase from P. denitrificans contains three to five non-haem, non-iron-sulphur iron atoms as prosthetic groups, predominantly co-ordinated by carboxylate ligands. The interaction of the enzyme with the electron-accepting proteins cytochrome c550 and pseudoazurin is mainly hydrophobic. The catalytic mechanism of hydroxylamine oxidase from P. denitrificans is different from the enzyme from N. europaea because the production of nitrite by the former requires molecular oxygen. Under anaerobic conditions the enzyme makes nitrous oxide as a sole product.

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25

LÉON, Sébastien, Brigitte TOURAINE, Jean-François BRIAT, and Stéphane LOBRÉAUX. "The AtNFS2 gene from Arabidopsis thaliana encodes a NifS-like plastidial cysteine desulphurase." Biochemical Journal 366, no. 2 (September 1, 2002): 557–64. http://dx.doi.org/10.1042/bj20020322.

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NifS-like proteins are cysteine desulphurases required for the mobilization of sulphur from cysteine. They are present in all organisms, where they are involved in iron–sulphur (Fe–S) cluster biosynthesis. In eukaryotes, these enzymes are present in mitochondria, which are the major site for Fe–S cluster assembly. The genome of the model plant Arabidopsis thaliana contains two putative NifS-like proteins. A cDNA corresponding to one of them was cloned by reverse-transcription PCR, and named AtNFS2. The corresponding transcript is expressed in many plant tissues. It encodes a protein highly related (75% similarity) to the slr0077-gene product from Synechocystis PCC 6803, and is predicted to be targeted to plastids. Indeed, a chimaeric AtNFS2–GFP fusion protein, containing one-third of AtNFS2 from its N-terminal end, was addressed to chloroplasts. Overproduction in Escherichia coli and purification of recombinant AtNFS2 protein enabled one to demonstrate that it bears a pyridoxal 5′-phosphate-dependent cysteine desulphurase activity in vitro, thus being the first NifS homologue characterized to date in plants. The putative physiological functions of this gene are discussed, including the attractive hypothesis of a possible role in Fe–S cluster assembly in plastids.

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Osterode, Wolf, Gerald Falkenberg, and Fritz Wrba. "Copper and Trace Elements in Gallbladder form Patients with Wilson’s Disease Imaged and Determined by Synchrotron X-ray Fluorescence." Journal of Imaging 7, no. 12 (December 3, 2021): 261. http://dx.doi.org/10.3390/jimaging7120261.

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Investigations about suspected tissue alterations and the role of gallbladder in Wilson’s disease (WD)—an inherited genetic disease with impaired copper metabolism—are rare. Therefore, tissue from patients with genetically characterised WD was investigated by microscopic synchrotron X-ray fluorescence (µSRXRF). For two-dimensional imaging and quantification of elements, X-ray spectra were peak-fitted, and the net peak intensities were normalised to the intensity of the incoming monochromatic beam intensity. Concentrations were calculated by fundamental parameter-based program quant and external standardisation. Copper (Cu), zinc (Zn) and iron (Fe) along with sulphur (S) and phosphorus (P) mappings could be demonstrated in a near histological resolution. All these elements were increased compared to gallbladder tissue from controls. Cu and Zn and Fe in WD-GB were mostly found to be enhanced in the epithelium. We documented a significant linear relationship with Cu, Zn and sulphur. Concentrations of Cu/Zn were roughly 1:1 while S/Cu was about 100:1, depending on the selected areas for investigation. The significant linear relationship with Cu, Zn and sulphur let us assume that metallothioneins, which are sulphur-rich proteins, are increased too. Our data let us suggest that the WD gallbladder is the first in the gastrointestinal tract to reabsorb metals to prevent oxidative damage caused by metal toxicity.

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Sideri, Theodora C., Sylvia A. Willetts, and Simon V. Avery. "Methionine sulphoxide reductases protect iron–sulphur clusters from oxidative inactivation in yeast." Microbiology 155, no. 2 (February 1, 2009): 612–23. http://dx.doi.org/10.1099/mic.0.022665-0.

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Methionine residues and iron–sulphur (FeS) clusters are primary targets of reactive oxygen species in the proteins of micro-organisms. Here, we show that methionine redox modifications help to preserve essential FeS cluster activities in yeast. Mutants defective for the highly conserved methionine sulphoxide reductases (MSRs; which re-reduce oxidized methionines) are sensitive to many pro-oxidants, but here exhibited an unexpected copper resistance. This phenotype was mimicked by methionine sulphoxide supplementation. Microarray analyses highlighted several Cu and Fe homeostasis genes that were upregulated in the mxrΔ double mutant, which lacks both of the yeast MSRs. Of the upregulated genes, the Cu-binding Fe transporter Fet3p proved to be required for the Cu-resistance phenotype. FET3 is known to be regulated by the Aft1 transcription factor, which responds to low mitochondrial FeS-cluster status. Here, constitutive Aft1p expression in the wild-type reproduced the Cu-resistance phenotype, and FeS-cluster functions were found to be defective in the mxrΔ mutant. Genetic perturbation of FeS activity also mimicked FET3-dependent Cu resistance. 55Fe-labelling studies showed that FeS clusters are turned over more rapidly in the mxrΔ mutant than the wild-type, consistent with elevated oxidative targeting of the clusters in MSR-deficient cells. The potential underlying molecular mechanisms of this targeting are discussed. Moreover, the results indicate an important new role for cellular MSR enzymes in helping to protect the essential function of FeS clusters in aerobic settings.

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Senn, Hans, and Kurt Wüthrich. "Amino acid sequence, haem-iron co-ordination geometry and functional properties of mitochondrial and bacterial c-type cytochromes." Quarterly Reviews of Biophysics 18, no. 2 (May 1985): 111–34. http://dx.doi.org/10.1017/s0033583500005151.

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Cytochromes are found in all biological oxidation Systems which involve transport of reducing equivalents through organized chains of membrane bound intermediates, regardless of the ultimate oxidant (Keilin, 1966; Bartsch, 1978; Meyer & Kamen, 1982). Thus, cytochromes are present not only in the aerobic mitochondrial and bac-terial respiratory chain, but are also found in much more diversified procariotic Systems, including all varieties of facultative anaerobes (nitrate and nitrite reducers), obligate anaerobes (sulphate reducers and phototrophic sulphur bacteria), facultative photoheterotrophes (phototrophic non-sulphur purple bacteria), and the photoautotrophic cyanobacteria (blue-green algae). Among the different types of cytochromes occurring in the cell, the soluble c-type cytochromes (‘class I’, Meyer & Kamen, 1982) are the most abundant and best characterized group of proteins (Bartsch, 1978; Meyer & Kamen, 1982; Dickerson & Timkovitch, 1975; Lemberg & Barrett, 1973; Salemme, 1977; Ferguson-Miller, Brautigan & Margoliash, 1979). The amino acid sequences of more than 80 mitochrondrial and close to 40 bacterial cytochromes c are known (Meyer & Kamen, 1982; Dickerson & Timkovitch, 1975; Schwartz & Dayhoff, 1976; Dayhoff & Barker, 1978).

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Corbett, J. A., J. L. Wang, J. H. Hughes, B. A. Wolf, M. A. Sweetland, J. R. Lancaster, and M. L. McDaniel. "Nitric oxide and cyclic GMP formation induced by interleukin 1β in islets of Langerhans. Evidence for an effector role of nitric oxide in islet dysfunction." Biochemical Journal 287, no. 1 (October 1, 1992): 229–35. http://dx.doi.org/10.1042/bj2870229.

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Treatment of pancreatic islets with interleukin 1 (IL-1) results in a time-dependent inhibition of glucose-stimulated insulin secretion which has recently been demonstrated to be dependent on the metabolism of L-arginine to nitric oxide. In this report IL-1 beta is shown to induce the accumulation of cyclic GMP (cGMP) in a time-dependent fashion that mimics the time-dependent inhibition of insulin secretion by IL-1 beta. The accumulation of cGMP is dependent on nitric oxide synthase activity, since NG-monomethyl-L-arginine (a competitive inhibitor of nitric oxide synthase) prevents IL-1 beta-induced cGMP accumulation. cGMP formation and nitrite production induced by IL-1 beta pretreatment of islets are also blocked by the protein synthesis inhibitor, cycloheximide. The formation of cGMP does not appear to mediate the inhibitory effects of IL-1 beta on insulin secretion since a concentration of cycloheximide (1 microM) that blocks IL-1 beta-induced inhibition of glucose-stimulated insulin secretion and nitric oxide formation does not prevent cGMP accumulation, thus dissociating the two events. By using e.p.r. spectroscopy, IL-1 beta is shown to induce the formation of a g = 2.04 iron-nitrosyl feature in islets which is prevented by cycloheximide, demonstrating the requirement of protein synthesis for IL-1 beta-induced nitric oxide formation. Iron-nitrosyl complex-formation by islets confirms that IL-1 beta induces the generation of nitric oxide by islets, and provides evidence indicating that nitric oxide mediates destruction of iron-sulphur clusters of iron-containing enzymes. Consistent with the destruction of iron-sulphur centres is the finding that pretreatment of islets with IL-1 beta results in an approx. 60% inhibition of mitochondrial oxidation of D-glucose to CO2. Inhibition of islet glucose oxidation appears to be mediated by nitric oxide since both NMMA and cycloheximide prevent IL-1 beta-induced inhibition of glucose oxidation. These results show that IL-1 beta-induced nitric oxide formation parallels the ability of IL-1 beta to inhibit glucose-stimulated insulin secretion by islets, and that protein synthesis is required for IL-1 beta-induced nitric oxide formation. These results also suggest that nitric oxide mediates IL-1 beta-induced inhibitory effects on the pancreatic beta-cell by functioning as an effector molecule responsible for the destruction of iron-sulphur centres of iron-containing proteins, resulting in an impairment of mitochondrial function.

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Hutcheon, G. W., and A. Bolhuis. "The archaeal twin-arginine translocation pathway." Biochemical Society Transactions 31, no. 3 (June 1, 2003): 686–89. http://dx.doi.org/10.1042/bst0310686.

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The twin-arginine translocation (Tat) pathway is a system with the unique ability to export proteins in a fully folded conformation. Its main components are TatA, TatB and TatC, all of which are required for Tat-dependent export. The Tat pathway is found in several Archaea, and in most of them a moderate number of predicted Tat-dependent substrates are present. Putative substrates include those binding cofactors such as iron–sulphur clusters and molybdopterin. In these Archaea, the role of the Tat pathway seems to be similar to that of bacteria: the export of a small subset of proteins that fold before translocation across the cytoplasmic membrane. The exception to this is the Tat system of the halophilic archaeon Halobacterium sp. NRC-1. In this organism, the majority of extra-cytoplasmic proteins are predicted to use the Tat pathway, which is, most likely, a specific adaptation to its particular lifestyle in highly saline conditions.

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Balk, J., A. J. Pierik, D. J. Aguilar Netz, U. Mühlenhoff, and R. Lill. "Nar1p, a conserved eukaryotic protein with similarity to Fe-only hydrogenases, functions in cytosolic iron-sulphur protein biogenesis." Biochemical Society Transactions 33, no. 1 (February 1, 2005): 86–89. http://dx.doi.org/10.1042/bst0330086.

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The genome of the yeast Saccharomyces cerevisiae encodes the essential protein Nar1p that is conserved in virtually all eukaryotes and exhibits striking sequence similarity to bacterial iron-only hydrogenases. Previously, we have shown that Nar1p is an Fe-S protein and that assembly of its co-factors depends on the mitochondrial Fe-S cluster biosynthesis apparatus. Using functional studies in vivo, we demonstrated that Nar1p has an essential role in the maturation of cytosolic and nuclear, but not of mitochondrial, Fe-S proteins [Balk, Pierik, Aguilar Netz, Mühlenhoff and Lill (2004) EMBO J. 23, 2105–2115]. Here we provide further spectroscopic evidence that Nar1p possesses two Fe-S clusters. We also show that Nar1p is required for Fe-S cluster assembly on the P-loop NTPase Nbp35p, another newly identified component of the cytosolic Fe-S protein assembly machinery. These data suggest a complex biochemical pathway of extra-mitochondrial Fe-S protein biogenesis involving unique eukaryotic proteins.

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Chebon-Bore, Lorna, Taremekedzwa Allan Sanyanga, Colleen Varaidzo Manyumwa, Afrah Khairallah, and Özlem Tastan Bishop. "Decoding the Molecular Effects of Atovaquone Linked Resistant Mutations on Plasmodium falciparum Cytb-ISP Complex in the Phospholipid Bilayer Membrane." International Journal of Molecular Sciences 22, no. 4 (February 21, 2021): 2138. http://dx.doi.org/10.3390/ijms22042138.

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Atovaquone (ATQ) is a drug used to prevent and treat malaria that functions by targeting the Plasmodium falciparum cytochrome b (PfCytb) protein. PfCytb catalyzes the transmembrane electron transfer (ET) pathway which maintains the mitochondrial membrane potential. The ubiquinol substrate binding site of the protein has heme bL, heme bH and iron-sulphur [2FE-2S] cluster cofactors that act as redox centers to aid in ET. Recent studies investigating ATQ resistance mechanisms have shown that point mutations of PfCytb confer resistance. Thus, understanding the resistance mechanisms at the molecular level via computational approaches incorporating phospholipid bilayer would help in the design of new efficacious drugs that are also capable of bypassing parasite resistance. With this knowledge gap, this article seeks to explore the effect of three drug resistant mutations Y268C, Y268N and Y268S on the PfCytb structure and function in the presence and absence of ATQ. To draw reliable conclusions, 350 ns all-atom membrane (POPC:POPE phospholipid bilayer) molecular dynamics (MD) simulations with derived metal parameters for the holo and ATQ-bound -proteins were performed. Thereafter, simulation outputs were analyzed using dynamic residue network (DRN) analysis. Across the triplicate MD runs, hydrophobic interactions, reported to be crucial in protein function were assessed. In both, the presence and absence of ATQ and a loss of key active site residue interactions were observed as a result of mutations. These active site residues included: Met 133, Trp136, Val140, Thr142, Ile258, Val259, Pro260 and Phe264. These changes to residue interactions are likely to destabilize the overall intra-protein residue communication network where the proteins’ function could be implicated. Protein dynamics of the ATQ-bound mutant complexes showed that they assumed a different pose to the wild-type, resulting in diminished residue interactions in the mutant proteins. In summary, this study presents insights on the possible effect of the mutations on ATQ drug activity causing resistance and describes accurate MD simulations in the presence of the lipid bilayer prior to conducting inhibitory drug discovery for the PfCytb-iron sulphur protein (Cytb-ISP) complex.

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Tamuhla, Tsaone, Lydia Joubert, Danicke Willemse, and Monique J. Williams. "SufT is required for growth of Mycobacterium smegmatis under iron limiting conditions." Microbiology 166, no. 3 (March 1, 2020): 296–305. http://dx.doi.org/10.1099/mic.0.000881.

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Iron-sulphur (FeS) clusters are versatile cofactors required for a range of biological processes within cells. Due to the reactive nature of the constituent molecules, assembly and delivery of these cofactors requires a multi-protein machinery in vivo. In prokaryotes, SufT homologues are proposed to function in the maturation and transfer of FeS clusters to apo-proteins. This study used targeted gene deletion to investigate the role of SufT in the physiology of mycobacteria, using Mycobacterium smegmatis as a model organism. Deletion of the sufT gene in M. smegmatis had no impact on growth under standard culture conditions and did not significantly alter activity of the FeS cluster dependent enzymes succinate dehydrogenase (SDH) and aconitase (ACN). Furthermore, the ΔsufT mutant was no more sensitive than the wild-type strain to the redox cycler 2,3-dimethoxy-1,4-naphthoquinone (DMNQ), or the anti-tuberculosis drugs isoniazid, clofazimine or rifampicin. In contrast, the ΔsufT mutant displayed a growth defect under iron limiting conditions, and an increased requirement for iron during biofilm formation. This data suggests that SufT is an accessory factor in FeS cluster biogenesis in mycobacteria which is required under conditions of iron limitation.

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Nakamoto, Masami, Koji Tanaka, and Toshio Tanaka. "A 4Fe–4S cluster with 1-adamantanethiolate ligand as a synthetic analogue of high potential iron–sulphur proteins." J. Chem. Soc., Chem. Commun., no. 21 (1988): 1422–23. http://dx.doi.org/10.1039/c39880001422.

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Homma, Takujiro, Sho Kobayashi, and Junichi Fujii. "Cysteine preservation confers resistance to glutathione-depleted cells against ferroptosis via CDGSH iron sulphur domain-containing proteins (CISDs)." Free Radical Research 54, no. 6 (June 2, 2020): 397–407. http://dx.doi.org/10.1080/10715762.2020.1780229.

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36

Høyer-Hansen, Gunilla, Lisbeth Skou Hønberg, and David J. Simpson. "Monoclonal antibodies used for the characterization of the two putative iron-sulphur centre proteins associated with photosystem I." Carlsberg Research Communications 50, no. 1 (January 1985): 23–35. http://dx.doi.org/10.1007/bf02910535.

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37

Nilavongse, Arjaree, T. Harma C. Brondijk, Tim W. Overton, David J. Richardson, Emily R. Leach, and Jeffrey A. Cole. "The NapF protein of the Escherichia coli periplasmic nitrate reductase system: demonstration of a cytoplasmic location and interaction with the catalytic subunit, NapA." Microbiology 152, no. 11 (November 1, 2006): 3227–37. http://dx.doi.org/10.1099/mic.0.29157-0.

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The periplasmic nitrate reductase of Escherichia coli is important during anaerobic growth in low-nitrate environments. The nap operon encoding this nitrate reductase comprises seven genes including a gene, napF, that encodes a putative cytoplasmic iron–sulphur protein of uncertain subcellular location and function. In this study, N-terminal sequence analysis, cell fractionation coupled with immunoblotting and construction of LacZ and PhoA fusion proteins were used together to establish that NapF is located in the E. coli cytoplasm. A bacterial two-hybrid protein–protein interaction system was used to demonstrate that NapF interacted in the cytoplasm with the terminal oxidoreductase NapA, but that it did not self-associate or interact with other electron-transport components of the Nap system, NapC, NapG or NapH, or with another cytoplasmic component, NapD. NapF, purified as a His6-tagged protein, exhibited spectral properties characteristic of an iron–sulphur protein. This protein was able to pull down NapA from soluble extracts of E. coli. A growth-based assay for NapF function in intact cell cultures was developed and applied to assess the effect of mutation of a number of conserved amino acids. It emerged that neither a highly conserved N-terminal double-arginine motif, nor a conserved proline motif, is essential for NapF-dependent growth. The combined data indicate that NapF plays one or more currently unidentified roles in the post-translational modification of NapA prior to the export of folded NapA via the twin-arginine translocation pathway into the periplasm.

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Popovic, Rebeka, Ivana Celardo, Yizhou Yu, Ana C. Costa, Samantha H. Y. Loh, and L. Miguel Martins. "Combined Transcriptomic and Proteomic Analysis of Perk Toxicity Pathways." International Journal of Molecular Sciences 22, no. 9 (April 27, 2021): 4598. http://dx.doi.org/10.3390/ijms22094598.

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In Drosophila, endoplasmic reticulum (ER) stress activates the protein kinase R-like endoplasmic reticulum kinase (dPerk). dPerk can also be activated by defective mitochondria in fly models of Parkinson’s disease caused by mutations in pink1 or parkin. The Perk branch of the unfolded protein response (UPR) has emerged as a major toxic process in neurodegenerative disorders causing a chronic reduction in vital proteins and neuronal death. In this study, we combined microarray analysis and quantitative proteomics analysis in adult flies overexpressing dPerk to investigate the relationship between the transcriptional and translational response to dPerk activation. We identified tribbles and Heat shock protein 22 as two novel Drosophila activating transcription factor 4 (dAtf4) regulated transcripts. Using a combined bioinformatics tool kit, we demonstrated that the activation of dPerk leads to translational repression of mitochondrial proteins associated with glutathione and nucleotide metabolism, calcium signalling and iron-sulphur cluster biosynthesis. Further efforts to enhance these translationally repressed dPerk targets might offer protection against Perk toxicity.

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Avenot, H. F., A. Sellam, G. Karaoglanidis, and T. J. Michailides. "Characterization of Mutations in the Iron-Sulphur Subunit of Succinate Dehydrogenase Correlating with Boscalid Resistance in Alternaria alternata from California Pistachio." Phytopathology® 98, no. 6 (June 2008): 736–42. http://dx.doi.org/10.1094/phyto-98-6-0736.

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Thirty-eight isolates of Alternaria alternata from pistachio orchards with a history of Pristine (pyraclostrobin + boscalid) applications and displaying high levels of resistance to boscalid fungicide (mean EC50 values >500 μg/ml) were identified following mycelial growth tests. A cross-resistance study revealed that the same isolates were also resistant to carboxin, a known inhibitor of succinate dehydrogenase (Sdh). To determine the genetic basis of boscalid resistance in A. alternata the entire iron sulphur gene (AaSdhB) was isolated from a fungicide-sensitive isolate. The deduced amino-acid sequence showed high similarity with iron sulphur proteins (Ip) from other organisms. Comparison of AaSdhB full sequences from sensitive and resistant isolates revealed that a highly conserved histidine residue (codon CAC in sensitive isolates) was converted to either tyrosine (codon TAC, type I mutants) or arginine (codon CGC, type II mutants) at position 277. In other fungal species this residue is involved in carboxamide resistance. In this study, 10 and 5 mutants were of type I and type II respectively, while 23 other resistant isolates (type III mutants) had no mutation in the histidine codon. The point mutation detected in type I mutants was used to design a pair of allele-specific polymerase chain reaction (PCR) primers to facilitate rapid detection. A PCR-restriction fragment length polymorphism (RFLP) assay in which amplified gene fragments were digested with AciI was successfully employed for the diagnosis of type II mutants. The relevance of these modifications in A. alternata AaSdhB sequence in conferring boscalid resistance is discussed.

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Panahi, Yunes, Ahad Shahbazi, Mostafa Naderi, Khosrow Jadidi, and Amirhossein Sahebkar. "Sulfur Mustard-related Ocular Complications: A Review of Proteomic Alterations and Pathways Involved." Current Pharmaceutical Design 24, no. 24 (November 8, 2018): 2849–54. http://dx.doi.org/10.2174/1381612824666180903112218.

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Sulphur mustard (SM; (2, 2'-dichloroethylsulfide)) was used for the first time in 1917, during the World War I. SM mainly induces DNA damage, oxidative stress, and inflammation. This compound injures the respiratory system, eyes, skin and the endocrine, gastrointestinal, and hematopoietic systems. However, due to the high lipophilicity of the SM and the lipophilic nature of the tear film, and also due to the direct contact of the eyes with the environment, the eyes are the most vulnerable part of the body to SM. SM causes several proteomic alterations in the eye. It increases the production and activity of inflammatory proteins, reduces the concentration of antioxidant proteins and activates the proteins involved in the onset of apoptosis. In this study, we reviewed SM-related proteomic alterations and the association of the found proteins with other eye disorders and diseases. Furthermore, using pathway enrichment analysis, we found the most central biological processes involved in the emergence of complications caused by SM. Our results revealed that deficient cellular homeostasis, especially in terms of iron-dependent regulations, as well as pathological changes in vascular endothelial growth factor (VEGF) expression, is the most central biological process involved in eye injuries caused by SM.

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Cleeter, M. W., and C. I. Ragan. "The polypeptide composition of the mitochondrial NADH: ubiquinone reductase complex from several mammalian species." Biochemical Journal 230, no. 3 (September 15, 1985): 739–46. http://dx.doi.org/10.1042/bj2300739.

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The polypeptide composition of isolated mitochondrial NADH:ubiquinone reductase (NADH dehydrogenase) is very similar to that of material immunoprecipitated from detergent-solubilized bovine heart submitochondrial particles by antisera to the holoenzyme. The specificity of the antisera for dehydrogenase polypeptides was determined by immunoblotting, which showed that antisera reacting with only a few proteins were able to immunoprecipitate all others in parallel. The polypeptide compositions of rat, rabbit and human NADH dehydrogenase were determined by immunoprecipitation of the enzyme from solubilized submitochondrial particles and proved to be very similar to that of the bovine heart enzyme, particularly in the high-Mr region. Further homologies in these and other species were explored by immunoblotting with antisera to the holoenzyme and monospecific antisera raised against iron-sulphur-protein subunits of the enzyme.

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42

Metzendorf, Christoph, Wenlin Wu, and Maria I. Lind. "Overexpression of Drosophila mitoferrin in l(2)mbn cells results in dysregulation of Fer1HCH expression." Biochemical Journal 421, no. 3 (July 15, 2009): 463–71. http://dx.doi.org/10.1042/bj20082231.

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Mrs3p and Mrs4p (Mrs3/4p) are yeast mitochondrial iron carrier proteins that play important roles in ISC (iron-sulphur cluster) and haem biosynthesis. At low iron conditions, mitochondrial and cytoplasmic ISC protein maturation is correlated with MRS3/4 expression. Zebrafish mitoferrin1 (mfrn1), one of two MRS3/4 orthologues, is essential for erythropoiesis, but little is known about the ubiquitously expressed paralogue mfrn2. In the present study we identified a single mitoferrin gene (dmfrn) in the genome of Drosophila melanogaster, which is probably an orthologue of mfrn2. Overexpression of dmfrn in the Drosophila l(2)mbn cell line (mbn-dmfrn) resulted in decreased binding between IRP-1A (iron regulatory protein 1A) and stem-loop RNA structures referred to as IREs (iron responsive elements). mbn-dmfrn cell lines also had increased cytoplasmic aconitase activity and slightly decreased iron content. In contrast, iron loading results in decreased IRP-1A–IRE binding, but increased cellular iron content, in experimental mbn-dmfrn and control cell lines. Iron loading also increases cytoplasmic aconitase activity in all cell lines, but with slightly higher activity observed in mbn-dmfrn cells. From this we concluded that dmfrn overexpression stimulates cytoplasmic ISC protein maturation, as has been reported for MRS3/4 overexpression. Compared with control cell lines, mbn-dmfrn cells had higher Fer1HCH (ferritin 1 heavy chain homologue) transcript and protein levels. RNA interference of the putative Drosophila orthologue of human ABCB7, a mitochondrial transporter involved in cytoplasmic ISC protein maturation, restored Fer1HCH transcript levels of iron-treated mbn-dmfrn cells to those of control cells grown in normal medium. These results suggest that dmfrn overexpression in l(2)mbn cells causes an ‘overestimation’ of the cellular iron content, and that regulation of Fer1HCH transcript abundance probably depends on cytoplasmic ISC protein maturation.

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Aldridge, Cassie, Edward Spence, Markus A. Kirkilionis, Lorenzo Frigerio, and Colin Robinson. "Tat-dependent targeting of Rieske iron-sulphur proteins to both the plasma and thylakoid membranes in the cyanobacterium Synechocystis PCC6803." Molecular Microbiology 70, no. 1 (August 11, 2008): 140–50. http://dx.doi.org/10.1111/j.1365-2958.2008.06401.x.

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44

Chen, Wen, Liangtao Li, Nathaniel B. Langer, Prasad N. Paradkar, Iman J. Schultz, Brigham B. Hyde, Orian S. Shirihai, Jerry Kaplan, and Barry H. Paw. "Abcb10 Physically Interacts with Mitoferrin1 to Enhance Its Stability for Heme Synthesis in the Erythroid Mitochondria." Blood 112, no. 11 (November 16, 2008): 530. http://dx.doi.org/10.1182/blood.v112.11.530.530.

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Abstract We previously described a zebrafish mutant, frascati (frs), with hypochromic anemia and erythroid maturation arrest. Using positional cloning, we identified mitoferrin1 (mfrn1, slc25a37) as the gene disrupted in frs mutants (Shaw GC, et al. 2006 Nature 440:96–100). Mfrn1, the principle iron-importer in the mitochondria, is essential for heme and iron-sulphur (Fe/S) cluster syntheses in erythroblasts, and is required for primitive and definitive erythropoiesis. The biochemistry for Mfrn1-mediated iron acquisition into the mitochondria of developing erythroblasts, however, is poorly understood. In order to identify Mfrn1-associated proteins involved in mitochondrial iron homeostasis, we employed the strategy of in vivo epitope-tagged affinity purification and mass spectrometry (MS). A “bait protein,” Biotag-mouse Mfrn1 (BT-Mfrn1), was engineered to affinity-purify the associated proteins. A series of control experiments were first conducted to demonstrate that the BT-Mfrn1 protein properly targeted to the mitochondria and functionally complemented the anemia in frs embryos. A two-dimensional Blue Native gel followed by SDS-PAGE and western blot showed Mfrn1 forms higher-order protein complexes with interacting proteins in the mitochondrial fraction. A stable mouse erythroleukemia (MEL) clone expressing BT-Mfrn1 protein was derived as a source for protein purification. Affinity-purified BT-Mfrn1 protein complexes were analyzed by MS in triplicate runs in comparison to control MEL cells. Abcb10, a GATA-1 induced ATP-binding cassette transporter highly expressed in hematopoietic tissues and involved in heme biosynthesis (Shirihai OS, et al. 2000EMBO J.19:2492–2502), was found as one of the proteins which physically associated with Mfrn1 during MEL differentiation. The Abcb10:Mfrn1 interaction was confirmed by immunoprecipitation (IP) and western analysis with endogenously expressed proteins in MEL cells and proteins expressed by transient transfection in heterologous cells. Mfrn1 was previously shown to have longer protein half-life in differentiated MEL cells compared to undifferentiated cells (Paradkar PN, et al. submitted). To test our hypothesis that the Abcb10:Mfrn1 interaction may enhance Mfrn1 protein stability, a pulse-chase assay using 35S-methionine labeled cells was performed, followed by IP. Abcb10 was found to stabilize Mfrn1 protein in COS7 cells co-transfected with Abcb10 and Mfrn1 compared to control cells transfected with Mfrn1 alone. Similar results were obtained when total steady-state Mfrn1 protein was evaluated by western analysis comparing lysates from Abcb10:Mfrn1 cotransfected and Mfrn1 transfected cells. Our data suggest that Abcb10 physically interacts with Mfrn1 to enhance its stability and promote Mfrn1-dependent mitochondrial heme biogenesis.

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45

Schejter, A., T. I. Koshy, T. L. Luntz, R. Sanishvili, I. Vig, and E. Margoliash. "Effects of mutating Asn-52 to isoleucine on the haem-linked properties of cytochrome c." Biochemical Journal 302, no. 1 (August 15, 1994): 95–101. http://dx.doi.org/10.1042/bj3020095.

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Asn-52 of rat cytochrome c and baker's yeast iso-1-cytochrome c was changed to isoleucine by site-directed mutagenesis and the mutated proteins expressed in and purified from cultures of transformed yeast. This mutation affected the affinity of the haem iron for the Met-80 sulphur in the ferric state and the reduction potential of the molecule. The yeast protein, in which the sulphur-iron bond is distinctly weaker than in vertebrate cytochromes c, became very similar to the latter: the pKa of the alkaline ionization rose from 8.3 to 9.4 and that of the acidic ionization decreased from 3.4 to 2.8. The rates of binding and dissociation of cyanide became markedly lower, and the affinity was lowered by half an order of magnitude. In the ferrous state the dissociation of cyanide from the variant yeast cytochrome c was three times slower than in the wild-type. The same mutation had analogous but less pronounced effects on rat cytochrome c: it did not alter the alkaline ionization pKa nor its affinity for cyanide, but it lowered its acidic ionization pKa from 2.8 to 2.2. These results indicate that the mutation of Asn-52 to isoleucine increases the stability of the cytochrome c closed-haem crevice as observed earlier for the mutation of Tyr-67 to phenylalanine [Luntz, Schejter, Garber and Margoliash (1989) Proc. Natl. Acad. Sci. U.S.A. 86, 3524-3528], because of either its effects on the hydrogen-bonding of an interior water molecule or a general increase in the hydrophobicity of the protein in the domain occupied by the mutated residues. The reduction potentials were affected in different ways; the Eo of rat cytochrome c rose by 14 mV whereas that of the yeast iso-1 cychrome c was 30 mV lower as a result of the change of Asn-52 to isoleucine.

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46

Okuno, Yohmei, Kouichi Uoto, Osamu Yonemitsu, and Takenori Tomohiro. "Stabilising effects on the 4Fe–4S core analogues for high-potential iron–sulphur proteins with a hydrophobic environment provided by macrocycles." J. Chem. Soc., Chem. Commun., no. 13 (1987): 1018–20. http://dx.doi.org/10.1039/c39870001018.

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47

Shergill, J. K., R. Cammack, J. H. Chen, M. J. Fisher, S. Madden, and H. H. Rees. "EPR spectroscopic characterization of the iron-sulphur proteins and cytochrome P-450 in mitochondria from the insect Spodoptera littoralis (cotton leafworm)." Biochemical Journal 307, no. 3 (May 1, 1995): 719–28. http://dx.doi.org/10.1042/bj3070719.

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EPR spectroscopy was used to investigate the cytochrome P-450-dependent steroid hydroxylase ecdysone 20-mono-oxygenase of the cotton leafworm (Spodoptera littoralis) and the redox centres associated with membranes from the fat-body mitochondrial fraction. Intense features at g = 2.42, 2.25 and 1.92 from oxidized mitochondrial membranes have been assigned to the low-spin haem form of ferricytochrome P-450, probably of ecdysone 20-mono-oxygenase. High-spin cytochrome P-450 (substrate-bound) was tentatively assigned to a signal at g = 8.0, which was detectable from membranes as prepared. An EPR signal characteristic of a [2Fe-2S] cluster detected from the soluble mitochondrial matrix fraction has been shown to be distinct from the signals associated with mitochondrial NADH dehydrogenase and succinate dehydrogenase, and has therefore been attributed to a ferredoxin. We conclude that the S. littoralis fat-body mitochondrial electron-transport system involved in steroid 20-hydroxylation comprises both ferredoxin and cytochrome P-450 components, and thus resembles the enzyme systems of adrenocortical mitochondria. EPR signals characteristic of the respiratory chain were also observed from fat-body mitochondria and assigned to the iron-sulphur clusters associated with Complex I (Centres N1, N2), Complex II (Centres S1, S3), Complex III (the Rieske centre), and the copper centre of Complex IV, demonstrating similarities to mammalian mitochondria. The reduced membrane fraction also yielded a major resonance at g = 2.09 and 1.88 characteristic of the [4Fe-4S] cluster of electron-transferring flavoprotein: ubiquinone oxidoreductase. As the fat-body is the major metabolic organ of insects, this protein is presumably required for the beta-oxidation of fatty acids in mitochondria. High-spin haem signals in the low-field region of spectra also demonstrated that the mitochondrial fraction contains relatively high concentrations of catalase.

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POTTER, Laura C., and Jeffrey A. COLE. "Essential roles for the products of the napABCD genes, but not napFGH, in periplasmic nitrate reduction by Escherichia coli K-12." Biochemical Journal 344, no. 1 (November 8, 1999): 69–76. http://dx.doi.org/10.1042/bj3440069.

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The seven nap genes at minute 47 on the Escherichia coli K-12 chromosome encode a functional nitrate reductase located in the periplasm. The molybdoprotein, NapA, is known to be essential for nitrate reduction. We now demonstrate that the two c-type cytochromes, the periplasmic NapB and the membrane-associated NapC, as well as a fourth polypeptide, NapD, are also essential for nitrate reduction in the periplasm by physiological substrates such as glycerol, formate and glucose. None of the three iron-sulphur proteins, NapF, NapG or NapH, are essential, irrespective of whether the bacteria are grown anaerobically in the presence of nitrate or fumarate as a terminal electron acceptor, or by glucose fermentation. Mutation of napD resulted in the total loss of Methyl Viologen-dependent nitrate reductase activity of the molybdoprotein, NapA, consistent with an earlier suggestion by others that NapD might be required for post-translational modification of NapA.

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Brandt, U., A. Abdrakhmanova, V. Zickermann, A. Galkin, S. Dröse, K. Zwicker, and S. Kerscher. "Structure–function relationships in mitochondrial complex I of the strictly aerobic yeast Yarrowia lipolytica." Biochemical Society Transactions 33, no. 4 (August 1, 2005): 840–44. http://dx.doi.org/10.1042/bst0330840.

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The obligate aerobic yeast Yarrowia lipolytica has been established as a powerful model system for the analysis of mitochondrial complex I. Using a combination of genomic and proteomic approaches, a total of 37 subunits was identified. Several of the accessory subunits are predicted to be STMD (single transmembrane domain) proteins. Site-directed mutagenesis of Y. lipolytica complex I has provided strong evidence that a significant part of the ubiquinone reducing catalytic core resides in the 49 kDa and PSST subunits and can be modelled using X-ray structures of distantly related enzymes, i.e. water-soluble [NiFe] hydrogenases from Desulfovibrio spp. Iron–sulphur cluster N2, which is related to the hydrogenase proximal cluster, is directly involved in quinone reduction. Mutagenesis of His226 and Arg141 of the 49 kDa subunit provided detailed insight into the structure–function relationships around cluster N2. Overall, our findings suggest that proton pumping by complex I employs long-range conformational interactions and ubiquinone intermediates play a critical role in this mechanism.

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Bergeron, Janique, Darakhshan Ahmad, Diane Barriault, Angèle Larose, Michel Sylvestre, and Justin Powlowski. "Identification and mapping of the gene translation products involved in the first steps of the Comamonas testosteroni B-356 biphenyl/chlorobiphenyl biodegradation pathway." Canadian Journal of Microbiology 40, no. 9 (September 1, 1994): 743–53. http://dx.doi.org/10.1139/m94-118.

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In this study, we have mapped Comamonas testosteroni B-356 genes encoding enzymes for the conversion of biphenyl and 4-chlorobiphenyl into the corresponding meta-cleavage compounds onto a 6.3-kb DNA fragment, and we have determined the subunit composition of the enzymes involved in this pathway. The various proteins encoded by this 6.3-kb DNA fragment and by subclones derived from it were overexpressed and selectively labelled using the T7 polymerase promoter system in Escherichia coli. They were then analyzed using SDS-PAGE, which allowed the encoding locus of each polypeptide to be mapped. Despite apparent dissimilarity in the congener selectivity patterns of the initial oxygenase of strain B-356 with those of Pseudomonas sp. strain LB400, the number and sizes of the polypeptides involved in the enzymatic conversion of biphenyl or 4-chlorobiphenyl into the meta-cleavage product appear to be similar in the two strains. In both strains, the bph operon encodes the following: the large (51-kDa polypeptide encoded by bphA) and the small (22-kDa polypeptide encoded by bphE) subunits of the iron sulphur protein, which is thought to interact directly with the substrate to introduce the oxygen molecule; the ferredoxin (12-kDa polypeptide encoded by bphF) involved in electron transfer from the reduced ferredoxin reductase to the oxidized iron sulphur protein; the 29-kDa polypeptide of the 2,3-dihydro-2,3-dihydroxybiphenyl dehydrogenase encoded by bphB; and the 32-kDa polypeptide of the 2,3-dihydroxybiphenyl-1,2-dioxygenase encoded by bphC, which catalyzes meta-1,2 fission of the aromatic ring. A major difference between strain B-356 and strain LB400 is that the bphG gene encoding biphenyl dioxygenase ferredoxin reductase is located outside the bph gene cluster in strain B-356. Several lines of evidence indicate that bphG is absent in clones carrying the bph operon from strain B-356.Key words: PCB, gene expression, biphenyl oxygenase, bph.

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Journal articles on the topic 'Iron sulphur proteins'

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