Disease relevance of CYC1

• The nucleotide sequence coding for bovine leukemia virus (BLV) envelope glycoprotein gp51 was inserted into a yeast-Escherichia coli shuttle vector carrying the promoter and secretion signal sequence of PHO5 (the yeast gene coding for repressible acid phosphatase) and the CYC1 transcriptional terminator [1].
• The interaction domain for cytochrome c on the cytochrome bc(1) complex was studied using a series of Rhodobacter sphaeroides cytochrome bc(1) mutants in which acidic residues on the surface of cytochrome c(1) were substituted with neutral or basic residues [2].
• Exposure to DETA-NO resulted in a decrease in Psim and concomitant release of cytochrome c and caspase-9 activation, which were enhanced by hypoxia [3].
• Anabaena Fld residues Asp144 and Glu145 align closely with rat P450 reductase residue Asp208, which has been shown by mutagenesis to be important in electron transfer to P4502B1 but not to cytochrome c (Shen, A. L., and Kasper, C. B. (1995) J. Biol. Chem. 270, 27475-27480) [4].
• Rhizobium phaseoli cytochrome c-deficient mutant induces empty nodules on Phaseolus vulgaris L [5].

High impact information on CYC1

• The enzyme's catalytic cycle consists of a reductive phase, in which the oxidized enzyme receives electrons from cytochrome c, and an oxidative phase, in which the reduced enzyme is oxidized by O2 [6].
• On the basis of x-ray diffraction data to a resolution of 2.9 angstroms, atomic models of most protein components of the bovine cytochrome bc1 complex were built, including core 1, core 2, cytochrome b, subunit 6, subunit 7, a carboxyl-terminal fragment of cytochrome c1, and an amino-terminal fragment of the iron-sulfur protein [7].
• Lymphocyte specificity to protein antigens. II. Fine specificity of T-cell activation with cytochrome c and derived peptides as antigenic probes [8].
• The pattern of specificity observed appeared to be haplotype (BDF1) dependent although similar conclusions about the fine specificity of T cells in the response to cytochrome c have been obtained in other strains but associated with different residues [8].
• We show that all cytochrome c oxidase (complex IV) of Saccharomyces cerevisiae is bound to cytochrome c reductase (complex III), which exists in three forms: the free dimer, and two supercomplexes comprising an additional one or two complex IV monomers [9].

Chemical compound and disease context of CYC1

• Respiration during hypoxia was also inhibited when N,N,N',N'-tetramethyl-p-phenylenediamine (0.5 mM) and ascorbate (5 mM) were used to reduce cytochrome c, suggesting that cytochrome oxidase was partially inhibited [10].
• In addition, we describe the results of calculations of C(alpha), C(beta), C(gamma)1, C(gamma)2, and C(delta) shifts in the two isoleucine residues in bovine pancreatic trypsin inhibitor and the four isoleucines in a cytochrome c and demonstrate that the side chain chemical shifts are strongly influenced by chi(2) torsion angle effects [11].
• Photolabelling with 8-azido-ATP of the reconstituted Paracoccus enzyme also increases the Km for cytochrome c which is completely prevented if ATP but not if ADP is present during illumination as was found with reconstituted cytochrome c oxidase from bovine heart [12].
• Following incubation with increasing amounts of DCCD, proton ejection was recorded in response to reductant pulses with reduced cytochrome c. Concentrations of DCCD which greatly reduced proton pumping by bovine cytochrome c oxidase used as a control were found to exert only a minor effect on proton translocation by Paracoccus oxidase [13].
• All nitroalkane oxidations by these three flavoenzymes are inhibited by Cu and Zn-superoxide dismutase of bovine blood, Mn-superoxide dismutases of bacilli, Fe-superoxide dismutase of Serratia marcescens, and other O2-. scavengers such as cytochrome c and NADH, but are not affected by hydroxyl radical scavengers such as mannitol [14].

Biological context of CYC1

• Enough cytochrome c in the respiratory chain is needed for keeping O(2)(*) and H(2)O(2) at a lower physiological level [15].
• Recent studies on cell apoptosis reveal that cytochrome c is responsible for the programmed cell death when it is released from mitochondria to cytoplasm [15].
• Yeast cells were transformed by a yeast-E. coli shuttle vector carrying the PHO5 promoter, the p24 gene and the CYC1 transcription terminator [16].
• Definition of cytochrome c binding domains by chemical modification: kinetics of reaction with beef mitochondrial reductase and functional organization of the respiratory chain [17].
• In the fused membranes, 55-60% of the cytochrome c oxidase molecules are oriented with the cytochrome c binding site at the outer surface of the membrane [18].

Anatomical context of CYC1

• Effect of cytochrome c on the generation and elimination of O2*- and H2O2 in mitochondria [15].
• The presence of a hydrophobic cluster near the COOH-terminal region indicates that the COOH-terminal region of cytochrome C1 associates with, or is buried in, the phospholipid bilayer of the mitochondrial membrane [19].
• The O(2)(*) and H(2)O(2) generation in cytochrome c-depleted Keilin-Hartree heart muscle preparation (HMP) is 7-8 times higher than that in normal HMP [15].
• Cytochrome oxidase (ferrocytochrome c:oxygen oxidoreductase, EC 1.9.3.1) of beef heart mitochondria, prepared by a standard method and brought to the highest purity level, is essentially inactive when tested in the aerobic assay involving oxidation of reduced cytochrome c by molecular oxygen [20].
• Bovine aortic endothelial cells were treated with chloramphenicol, which resulted in a decreased ratio of mitochondrial complex IV to cytochrome c and increased oxidant production in the cell [21].

Associations of CYC1 with chemical compounds

• The complete primary structure of bovine heart cytochrome c1 was established by analyses of peptide fragments prepared by digestion using trypsin, staphylococcal protease, and chymotrypsin and by cyanogen bromide cleavage of cytochrome c1 and its derivatives [19].
• With the electron-donor system ascorbate/N,N,N',N'-tetramethyl-p-phenylenediamine/cytochrome c, a high proton-motive force (greater than 130 mV), inside negative and alkaline, can be generated in the fused membrane, and this proton-motive force can drive secondary transport of several amino acids [18].
• By washing the complex with detergent on the hydrophobic interaction column, phospholipids were effectively depleted; 7 mol of cardiolipin per mol of cytochrome c1 was retained in the final sample [22].
• The particle first was mixed with an excess of cytochrome c in 1.5% cholate (wt/vol); slow removal of the detergent from the mixture was achieved by dialysis [23].
• Furthermore, enhancement can occur in the absence of cytochrome c binding and internalization, since B cells that were fixed with paraformaldehyde after treatment with F(ab')2 anti-Ig were more effective in presenting the carboxyl-terminal peptide than were untreated fixed cells [24].

Physical interactions of CYC1

• Deletion of residues 115-128 or 109-128 did not essentially affect adrenodoxin reductase binding as shown by nearly unchanged cytochrome c reduction activity [25].
• 13C NMR spectroscopic and X-ray crystallographic study of the role played by mitochondrial cytochrome b5 heme propionates in the electrostatic binding to cytochrome c [26].

Enzymatic interactions of CYC1

• Attempts to rationalize the kinetics of cytochrome c oxidation catalyzed by solubilized mitochondrial cytochrome c oxidase (ferrocytochrome c:oxygen oxidoreductase, EC 1.9.3.1) have been based on assumptions of productive complex formation (Michaelis-Menten approach) [27].
• No effect of 3-methoxybenzidine was observed on the adrenodoxin reductase and adrenodoxin-catalyzed reduction of cytochrome c by NADPH, and it is concluded that 3-methoxybenzidine acts on cytochrome P-450scc in inhibiting cholesterol side chain cleavage [28].

Regulatory relationships of CYC1

• Pre-treatment of cytochrome b561 with diethylpyrocarbonate suppressed the reduction of extravesicular cytochrome c significantly, confirming that the reduction was not due to leakage of ascorbate from the vesicles [29].
• The spin relaxation of the Rieske iron-sulfur cluster was enhanced by the paramagnetic cytochrome c1 and b566 hemes but not by cytochrome b562 [30].
• Binding to cytochrome c oxidase induces a conformational change in the cytochrome c molecule [31].
• Mechanistically, TNF-alpha-induced cell death was preceded by an efflux of mitochondrial cytochrome c into the cytosol and, subsequently, by a marked increase in the proapoptotic protein Bak and a decrease in the anti-apoptotic Bcl-xL protein content [32].
• Cocaine significantly increased caspase-3 activity that was blocked by the inhibitors of cytochrome c release (cyclosporin A), caspase-3 (Ac-DEVD-CHO), and caspase-9 (Z-LEHD-FMK), respectively [33].

Other interactions of CYC1

• No clear homology was found between cytochrome c1 and other membranous proteins such as cytochrome b5 or the subunits of cytochrome oxidase for which sequences have been reported [19].
• While the reduction of cytochrome c, reflecting the interaction between adrenodoxin and its reductase, and the interaction with CYP11B1 have not been significantly affected by the presence of the presequence, the binding affinity of preadrenodoxin to CYP11A1 is 5.5-fold lower than that of the mature form [34].
• We verified that purified cytochrome b561 can donate electron equivalents directly to cytochrome c. The purified cytochrome b561 was successfully reconstituted into cholesterol-phosphatidylcholine-phosphatidylglycerol vesicles by a detergent-dialysis and extrusion method [29].
• Treatment of adrenodoxin reductase with a highly purified preparation of neuraminidase demonstrates that neither the adrenodoxin-independent ferricyanide reductase activity nor the adrenodoxin-dependent cytochrome c reductase activity of the enzyme is affected by neuraminidase treatment [35].
• Our results suggest that FABP scavenges O2-, OH. and OCl. as indicated by the FABP inhibition of O2- -dependent reduction of cytochrome c, OH.-dependent hydroxybenzoic acid formation and OCl.-mediated chemiluminescence response [36].

Analytical, diagnostic and therapeutic context of CYC1

• Affinity chromatography purification of cytochrome c binding enzymes [37].
• Crystallization of part of the mitochondrial electron transfer chain: cytochrome c oxidase--cytochrome c complex [38].
• The generation of prostacyclin and leukotriene B4 were measured by radioimmunoassay, superoxide anion was measured by reduction of cytochrome c, and PAF was measured by bioassay [39].
• The stoichiometry of reducing equivalents per protomer for the complex molybdoflavoprotein xanthine oxidase has been re-examined by reductive titrations with sodium dithionite and anaerobic reoxidation with cytochrome c and phenazine methosulfate of dithionite- or photo-reduced enzyme [40].
• Gel filtration of bovine liver extract on a Sephadex G-200 column resolved three macromolecular fractions with dihydropteridine reductase-dependent cytochrome c reducing activity [41].

References