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1.
Biochim Biophys Acta ; 1857(12): 1935-1942, 2016 12.
Artigo em Inglês | MEDLINE | ID: mdl-27693469

RESUMO

Mitochondrial complex I is a 1MDa membrane protein complex with a central role in aerobic energy metabolism. The bioenergetic core functions are executed by 14 central subunits that are conserved from bacteria to man. Despite recent progress in structure determination, our understanding of the function of the ~30 accessory subunits associated with the mitochondrial complex is still limited. We have investigated the structure of complex I from the aerobic yeast Yarrowia lipolytica by cryo-electron microscopy. Our density map at 7.9Å resolution closely matches the 3.6-3.9Å X-ray structure of the Yarrowia lipolytica complex. However, the cryo-EM map indicated an additional subunit on the side of the matrix arm above the membrane surface, pointing away from the membrane arm. The density, which is not present in any previously described complex I structure and occurs in about 20 % of the particles, was identified as the accessory sulfur transferase subunit ST1. The Yarrowia lipolytica complex I preparation is active in generating H2S from the cysteine derivative 3-mercaptopyruvate, catalyzed by ST1. We thus provide evidence for a link between respiratory complex I and mitochondrial sulfur metabolism.


Assuntos
Microscopia Crioeletrônica , Complexo I de Transporte de Elétrons/metabolismo , Metabolismo Energético , Proteínas Fúngicas/metabolismo , Mitocôndrias/enzimologia , Transferases de Grupos de Enxofre/metabolismo , Enxofre/metabolismo , Yarrowia/enzimologia , Catálise , Cisteína/análogos & derivados , Cisteína/metabolismo , Complexo I de Transporte de Elétrons/química , Complexo I de Transporte de Elétrons/genética , Complexo I de Transporte de Elétrons/ultraestrutura , Escherichia coli/enzimologia , Escherichia coli/genética , Proteínas Fúngicas/química , Proteínas Fúngicas/genética , Proteínas Fúngicas/ultraestrutura , Sulfeto de Hidrogênio/metabolismo , Mitocôndrias/ultraestrutura , Modelos Moleculares , Conformação Proteica , Relação Estrutura-Atividade , Transferases de Grupos de Enxofre/química , Transferases de Grupos de Enxofre/genética , Transferases de Grupos de Enxofre/ultraestrutura , Yarrowia/genética , Yarrowia/ultraestrutura
2.
Biochemistry ; 46(38): 10990-8, 2007 Sep 25.
Artigo em Inglês | MEDLINE | ID: mdl-17760419

RESUMO

The central protein of the four component sulfur oxidizing (Sox) enzyme system of Paracoccus pantotrophus, SoxYZ, carries at the SoxY subunit the covalently bound sulfur substrate which the other three proteins bind, oxidize, and release as sulfate. SoxYZ of different preparations resulted in different specific thiosulfate-oxidizing activities of the reconstituted Sox enzyme system. From these preparations SoxYZ was activated up to 24-fold by different reductants with disodium sulfide being the most effective and yielded a uniform specific activity of the Sox system. The activation comprised the activities with hydrogen sulfide, thiosulfate, and sulfite. Sulfide-activation decreased the predominant beta-sheet character of SoxYZ by 4%, which caused a change in its conformation as determined by infrared spectroscopy. Activation of SoxYZ by sulfide exposed the thiol of the C-terminal Cys-138 of SoxY as evident from alkylation by 4-acetamido-4'-maleimidylstilbene-2,2'-disulfonic acid. Also, SoxYZ activation enhanced the formation of the Sox(YZ)2 heterotetramer as evident from density gradient gel electrophoresis. The tetramer was formed due to an interprotein disulfide between SoxY to yield a SoxY-Y dimer as determined by combined high pressure liquid chromatography and mass spectrometry. The significance of the conformational change of SoxYZ and the interprotein disulfide between SoxY-Y is discussed.


Assuntos
Proteínas de Bactérias/metabolismo , Proteínas de Transporte/química , Dissulfetos/metabolismo , Oxirredutases atuantes sobre Doadores de Grupo Enxofre/química , Oxirredutases atuantes sobre Doadores de Grupo Enxofre/metabolismo , Transferases de Grupos de Enxofre/química , Transferases de Grupos de Enxofre/metabolismo , Proteínas de Bactérias/química , Cisteína/metabolismo , Dimerização , Ativação Enzimática , Modelos Biológicos , Conformação Molecular , Complexos Multienzimáticos , Oxirredução , Paracoccus pantotrophus/enzimologia , Conformação Proteica , Isomerases de Dissulfetos de Proteínas , Estrutura Terciária de Proteína , Subunidades Proteicas , Espectroscopia de Infravermelho com Transformada de Fourier , Estilbenos , Ácidos Sulfônicos , Enxofre/metabolismo , Tiossulfatos/metabolismo
3.
Steroids ; 70(14): 960-9, 2005 Dec 15.
Artigo em Inglês | MEDLINE | ID: mdl-16157357

RESUMO

Dehydroepiandrosterone and its sulfated form are commonly known as modulators of gamma-aminobutyrate A and N-methyl-D-aspartate receptors. In spite of poor permeability of the blood-brain barrier for sulfated steroids, high concentrations of dehydroepiandrosterone and also its sulfate have been found in brain tissue. Physiological concentrations of these neuromodulators are maintained by two enzymes present in the blood and many peripheral tissues, including the brain, namely, steroid sulfatase and neurosteroid sulfuryl transferase (NSST). This prompted us to investigate activities of these enzymes in primate brain tissue. Rather low neurosteroid sulfuryl transferase activity was detectable in in vitro incubations of cytosol fractions from male and female Macaca mulatta brains, dissected to cerebral cortex, subcortex, and cerebellum. In male monkeys, the highest activity was found in the cerebellum followed by cortex and subcortex. On the other hand, in female monkeys, the highest activity was determined in the cortex followed by subcortex and cerebellum. Steroid sulfatase activity was determined in in vitro microsomal samples from each of the above-mentioned brain regions. Specific activities in female cerebral regions declined in the order: cerebellum, cortex, and subcortex. In male monkeys, no significant difference among the studied regions was observed. Using dehydroepiandrosterone sulfate as a substrate, the apparent kinetic characteristics of steroid sulfatase were determined as follows: K(M) 36.10 +/- 8.33 microM, V(max) 8.38 +/- 1.68 nmol/h/mg protein. These results will serve as a basis for further studies concerning the pathophysiology of human brain tumors.


Assuntos
Encéfalo/enzimologia , Macaca mulatta , Esteril-Sulfatase/metabolismo , Transferases de Grupos de Enxofre/metabolismo , Animais , Bioensaio , Química Encefálica , Feminino , Concentração de Íons de Hidrogênio , Masculino , Espectrometria de Massas , Temperatura , Fatores de Tempo
4.
Pol J Pharmacol ; 53(3): 215-25, 2001.
Artigo em Inglês | MEDLINE | ID: mdl-11785922

RESUMO

The covalent modifications of sulfhydryl groups (-SH) may occur through oxidation to mixed disulfides (S-thiolation), S-nitrosylation, as well as persulfide and trisulfide formation. The latter possibilities of -SH group modification connected with compounds containing sulfur called sulfane sulfur are described in this paper. Sulfane sulfur compounds contain a labile, highly reactive sulfur atom at a reduced oxidation state with a valence of 0 or -1, covalently bound to another sulfur atom. These compounds include persulfides, polysulfides, polythionates, thiosulfate, elemental sulfur and disulfides, which enable tautomerization to thiosulfoxides. Sulfane sulfur compounds are formed in the anaerobic cysteine sulfur metabolism with the participation of such enzymes as cystathionase (CST), 3-mercaptopyruvate sulfurtransferase (MpST) and rhodanese (thiosulfate: cyanide sulfurtransferase). Compounds containing sulfane sulfur participate in cell regulation processes through activation or inactivation of some enzymes. Other important roles of sulfane sulfur compounds are their antioxidative properties, significance in the processes of carcinogenesis, participation in the tRNA sulfuration as well as an influence on the activity of immune cells. To recognize completely the biological role of compounds with sulfane sulfur it is necessary to have sensitive methods of quantitative determination, so a review of these methods is presented in this paper. Moreover, biosynthetic pathways and biological properties of these compounds have been discussed.


Assuntos
Compostos de Enxofre/metabolismo , Animais , Transformação Celular Neoplásica/metabolismo , Cisteína/metabolismo , Ativação Enzimática , Humanos , Metionina/metabolismo , Estresse Oxidativo/fisiologia , Processamento Pós-Transcricional do RNA/fisiologia , Compostos de Enxofre/análise , Transferases de Grupos de Enxofre/metabolismo
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