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Query: UNIPROT:P06889 (Mol)
 630,302 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The SCO1 gene of Saccharomyces cerevisiae encodes a 30 kDa protein which is specifically required for a post-translational step in the accumulation of subunits 1 and 2 of cytochrome c oxidase (COXI and COX-II). Antibodies directed against a beta-Gal::SCO1 fusion protein detect SCO1 in the mitochondrial fraction of yeast cells. The SCO1 protein is an integral membrane protein as shown by its resistance to alkaline extraction and by its solubilization properties upon treatment with detergents. Based on the results obtained by isopycnic sucrose gradient centrifugation and by digitonin treatment of mitochondria, SCO1 is a component of the inner mitochondrial membrane. Membrane localization is mediated by a stretch of 17 hydrophobic amino acids in the amino-terminal region of the protein. A truncated SCO1 derivative lacking this segment, is no longer bound to the membrane and simultaneously loses its biological function. The observation that membrane localization of SCO1 is affected in mitochondria of a rho0 strain, hints at the possible involvement of mitochondrially coded components in ensuring proper membrane insertion.
Mol Gen Genet 1991 Oct
PMID:Immunological identification of yeast SCO1 protein as a component of the inner mitochondrial membrane. 194 30

Further genetic evidence is provided here that Bradyrhizobium japonicum possesses a mitochondria-like electron-transport pathway: 2[H]----UQ----bc1----c----aa3----O2. Two Tn5-induced mutants, COX122 and COX132, having cytochrome c oxidase-negative phenotypes, were obtained and characterized. Mutant COX122 was defective in a novel gene, named cycM, which was responsible for the synthesis of a c-type cytochrome with an Mr of 20,000 (20K). This 20K cytochrome c appeared to catalyse electron transport from the cytochrome bc1 complex to the aa3-type terminal oxidase and, unlike mitochondrial cytochrome c, was membrane-bound in B. japonicum. The Tn5 insertion of mutant COX132 was localized in coxA, the structural gene for subunit I of cytochrome aa3. This finding also led to the cloning and sequencing of the corresponding wild-type coxA gene that encoded a 541-amino-acid protein with a predicted Mr of 59,247. The CoxA protein shared about 60% sequence identity with the cytochrome aa3 subunit I of mitochondria. The B. japonicum cycM and coxA mutants were able to fix nitrogen in symbiosis with soybean (Fix+). In contrast, mutants described previously which lacked the bc1 complex did not develop into endosymbiotic bacteroids and were thus Fix-. The data suggest that a symbiosis-specific respiratory chain exists in B. japonicum in which the electrons branch off at the bc1 complex.
Mol Microbiol 1990 Dec
PMID:Genetic analysis of the cytochrome c-aa3 branch of the Bradyrhizobium japonicum respiratory chain. 196 17

We show here that SNF1 and SSN6 are required for derepression of the glucose-repressible yeast genes COX6 and CYC1, which encode the mitochondrial proteins cytochrome c oxidase subunit VI and iso-1-cytochrome c, respectively. In an snf1 mutant genetic background, the transcription of both COX6 and CYC1 continued to be repressed after cells were shifted into derepressing media. In an ssn6 mutant genetic background, both COX6 and CYC1 were expressed constitutively at high levels in repressing media. SSN6 acted epistatically to SNF1 in the regulation of both cytochrome genes. These findings are similar to previous findings on the effects of SNF1 and SSN6 on SUC2 expression in Saccharomyces cerevisiae and are consistent with a model proposing that SNF1 exerts its effect through SSN6 on COX6 and CYC1.
Mol Cell Biol 1990 Mar
PMID:Release of two Saccharomyces cerevisiae cytochrome genes, COX6 and CYC1, from glucose repression requires the SNF1 and SSN6 gene products. 215 83

Subunit Va of Saccharomyces cerevisiae cytochrome c oxidase is a nucleus-encoded mitochondrial protein that is derived from a precursor with a 20-residue leader peptide. We previously reported that this leader peptide is required for import of subunit Va into mitochondria in vivo (S. M. Glaser, C. E. Trueblood, L. K. Dircks, R. O. Poyton, and M. G. Cumsky, J. Cell. Biochem. 36:275-278, 1988). Here we show that overproduction of a leaderless form of subunit Va circumvents the leader peptide requirement for import into mitochondria in vivo.
Mol Cell Biol 1990 Sep
PMID:Overexpression of a leaderless form of yeast cytochrome c oxidase subunit Va circumvents the requirement for a leader peptide in mitochondrial import. 216 43

The controversial subject of the subcellular location of myocardial adenosine production was studied employing density gradient fractionation of heart muscle combined with a novel method for analyzing distribution profiles based on multiple regression (correlation) analysis. Bungarotoxin binding, N-acetyl-beta-D-glucosaminidase, cytochrome c oxidase, NADPH-dependent cytochrome c reductase and lactate dehydrogenase were used as markers for the plasma membrane, lysosomes, mitochondria, sarcoplasmic reticulum and cytosol, respectively. The normalized distribution frequencies (fraction of total) of 5'-nucleotidase in mitochondria, lysosomes, plasma membranes, sarcoplasmic reticulum and cytosol in the 50 x g supernatant of total homogenate of heart muscle were found to be 0, 0.25, 0.44, 0.08 and 0.23, respectively. To increase the resolution power of this approach with respect to mitochondria, a crude mitochondrial fraction was also studied, in which the normalized distribution of 5'-nucleotidase in the homogenate was 0, 0.16 and 0.84 in mitochondria, plasma membranes and lysosomes, respectively. This mainly lysosomal 5'-nucleotidase activity was 61% inhibited by the alpha,beta-methylene analog of ADP, indicating that although the latter has been considered specific to the plasma membrane enzyme, it also inhibits the lysosomal enzyme. The intercellular distribution of 5'-nucleotidase was not studied, but the lack of this enzyme in the mitochondria indicate that the adenosine production observed during mitochondrial AMP production, e.g. during acetate oxidation in intact heart muscle, must involve AMP transport out from the mitochondria.
J Mol Cell Cardiol 1990 Jul
PMID:Subcellular distribution of myocardial 5'-nucleotidase. 223 47

The product of the Saccharomyces cerevisiae nuclear gene PET494 is required to promote the translation of the mitochondrial mRNA encoding cytochrome c oxidase subunit III (coxIII). The level of cytochrome c oxidase activity is affected by several different environmental conditions, which also influence coxIII expression. We have studied the regulation of PET494 to test whether the level of its expression might modulate coxIII translation in response to these conditions. A pet494::lacZ fusion was constructed and used to monitor PET494 expression. PET494 was regulated by oxygen availability: expression in a respiration-competent diploid strain grown anaerobically was one-fifth the level of expression in aerobically grown cells. However, since PET494 mRNA levels did not vary in response to oxygen deprivation, regulation by oxygen appears to occur at the translational level. This oxygen regulation was not mediated by heme, and PET494 expression was independent of the heme activator protein HAP2. The regulation of PET494 expression by carbon source was also examined. In cells grown on glucose-containing medium, PET494 was expressed at levels four- to sixfold lower than in cells grown on ethanol and glycerol. However, addition of ethanol to glucose-containing medium induced PET494 expression approximately twofold. PET494 transcript levels varied over a fourfold range in response to different carbon sources. The effects on PET494 expression of mutations in the SNF1, SNF2, SSN6, and HXK2 genes were also determined and found to be minimal.
Mol Cell Biol 1989 Feb
PMID:Control of the Saccharomyces cerevisiae regulatory gene PET494: transcriptional repression by glucose and translational induction by oxygen. 254 Apr 20

The yeast nuclear SCO1 gene is required for accumulation of the mitochondrially synthesized cytochrome c oxidase subunits I and II (COXI and COXII). We cloned and characterized the SCO1 gene. It codes for a 0.9 kb transcript. DNA sequence analysis predicts a 33 kDa protein. As shown by in vitro transcription and translation experiments in combination with import studies on isolated mitochondria, this protein is matured into a 30 kDa polypeptide which is tightly associated with a mitochondrial membrane. The possible function of the SCO1 gene product in the assembly of cytochrome c oxidase is discussed.
Mol Gen Genet 1989 Mar
PMID:Accumulation of the cytochrome c oxidase subunits I and II in yeast requires a mitochondrial membrane-associated protein, encoded by the nuclear SCO1 gene. 254 7

The COX5a and COX5b genes encode divergent forms of yeast cytochrome c oxidase subunit V. Although the polypeptide products of the two genes are functionally interchangeable, it is the Va subunit that is normally found in preparations of yeast mitochondria and cytochrome c oxidase. We show here that the predominance of subunit Va stems in part from the differential response of the two genes to the presence of molecular oxygen. Our results indicate that during aerobic growth, COX5a levels were high, while COX5b levels were low. Anaerobically, the pattern was reversed; COX5a levels dropped sevenfold, while those of COX5b were elevated sevenfold. Oxygen appeared to act at the level of transcription through heme, since the addition of heme restored an aerobic pattern of transcription to anaerobically grown cells and the effect of anaerobiosis on COX5 transcription was reproduced in strains containing a mutation in the heme-biosynthetic pathway (hem1). In conjunction with the oxygen-heme response, we determined that the product of the ROX1 gene, a trans-acting regulator of several yeast genes controlled by oxygen, is also involved in COX5 expression. These results, as well as our observation that COX5b expression varied significantly in certain yeast strains, indicate that the COX5 genes undergo a complex pattern of regulation. This regulation, especially the increase in COX5b levels anaerobically, may reflect an attempt to modulate the activity of a key respiratory enzyme in response to varying environmental conditions. The results presented here, as well as those from other laboratories, suggest that the induction or derepression of certain metabolic enzymes during anaerobiosis may be a common and important physiological response in yeast cells.
Mol Cell Biol 1989 May
PMID:Inverse regulation of the yeast COX5 genes by oxygen and heme. 254 55

Transcription of Saccharomyces cerevisiae COX6, the nuclear gene for subunit VI of cytochrome c oxidase, is activated in heme-proficient cells, requires the HAP2 gene, and is subject to glucose repression. In this study, by deletion mutagenesis of the COX6 promoter, we identified two regions that are important for transcription. The first was an upstream activation site, UAS6. It was found to be contained within an 84-base-pair (bp) sequence, between bp -256 and -340 of the COX6 translational initiation codon, and to contain sequences required for activation by heme and HAP2 and for release from glucose repression. When located upstream of a CYC1-lacZ fusion gene, deleted for both of its UASs, this segment functioned as a UAS element. Although UAS6 could promote expression in either orientation, it showed a marked orientation dependence in its response to HAP2 and the carbon source. The second region lay between bp -255 and -91. It contained two of the three major 5' termini of COX6 mRNAs and a putative TATA box. Deletion analysis of this region demonstrated that the putative TATA box is not required for transcription and that this region is separable into two redundant domains.
Mol Cell Biol 1989 Dec
PMID:Identification of an upstream activation sequence and other cis-acting elements required for transcription of COX6 from Saccharomyces cerevisiae. 255 97

The sequence of a region of honeybee (Apis mellifera ligustica) mitochondrial DNA, which contains the genes for cytochrome c oxidase subunits I and II (CO-I and CO-II) and inferred genes for tRNA(Asp), tRNA(Leu)UUR, tRNA(Lys), and tRNA(Trp), is presented. The region includes the segment previously identified as incurring a length increase in some other bee strains, including Africanized bees. The sequence information of this study and of that by Vlasak et al. shows that several shifts of tRNA genes have occurred between Apis and Drosophila, but shifts of other kinds of genes have yet to be demonstrated. The CO-I and CO-II gene sequences are both more A+T rich than are the corresponding Drosophila genes. Parsimony analyses using the mouse and Xenopus sequences as outgroups show significantly more amino acid substitutions on the branch to Apis (120) than on that to Drosophila (44), indicating a difference in the long-term evolutionary rates of hymenopteran and dipteran mtDNA.
Mol Biol Evol 1989 Jul
PMID:The CO-I and CO-II region of honeybee mitochondrial DNA: evidence for variation in insect mitochondrial evolutionary rates. 255 93


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