Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

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Query: EC:1.9.3.1 (cytochrome oxidase)
8,822 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

A gene encoding the 5 S rRNA-binding protein (YL3) in yeast (Saccharomyces cerevisiae) was further characterized with respect to its chromosomal localization, the controlling sequence regions, and the influence of 5 S rRNA gene expression. Sequence and chromosome blot analyses localized the gene on chromosome XVI immediately downstream of a cytochrome oxidase assembly gene, COXII. S1 nuclease protection studies identified two major initiation sites, 20 and 65 nucleotides upstream of the coding sequence, and a single polyadenylation site, 98 nucleotides downstream of the stop codon. Northern blot analyses and S1 nuclease protection indicated a normal pattern of gene regulation in media supporting alternate rates of growth, but significantly unbalanced regulation was observed in the presence of mutant 5 S rRNA genes which under-produce RNA and result in reduced growth rates. The results suggest a co-ordinating regulatory mechanism which maintains appropriate levels of 5 S rRNA-protein complex; an internal control region-like sequence in the upstream region of the YL3 gene is consistent with this feedback mechanism.
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PMID:Unbalanced regulation of the ribosomal 5 S RNA-binding protein in Saccharomyces cerevisiae expressing mutant 5 S rRNAs. 132 47

By use of restriction fragment length polymorphism analysis, we examined the liver mitochondrial DNA amplified by polymerase chain reaction from 60 Chinese subjects of 31 to 78 years of age. We found nine specific mtDNA polymorphisms that had never been reported before. Eleven subjects had an Alu I polymorphic site in the subunit 2 gene of NADH dehydrogenase, five had a Hae III polymorphic site in the cytochrome oxidase subunit 2 gene, and five had a Hinf I polymorphic site in the subunit 3 gene of cytochrome oxidase. No polymorphic site was found in the structural genes coding for subunits 1, 3, 4, 4L and 6 of NADH dehydrogenase, cytochrome b, and subunit 8 of ATP synthase. Detailed analysis of the RFLP data did not show age-dependent mtDNA polymorphisms. In addition, the analysis of the restriction patterns of all the mtDNAs revealed 12 mtDNA haplotypes in all the Chinese subjects examined. Among them, type 1 mtDNA was found to be the most predominant and comprised 63.3% of the total study subjects. The restriction patterns of type 1 mtDNA generated by all restriction enzymes were identical to those deduced from the Cambridge sequence of human mtDNA. About 8.3% of the subjects exhibited type 2 mtDNA, and 5% had types 3, 5 and 8 mtDNA, respectively. Each of the rest seven mtDNA types comprised about 2% of the samples. Moreover, type 1 mtDNA was found in the platelets of three white Americans. These findings suggest that type 2 to type 12 mtDNAs have come into existence through the generation or loss of specific polymorphic restriction sites in the mtDNA of the Chinese.
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PMID:Specific restriction fragment length polymorphism in liver mitochondrial DNA of the Chinese. 135 20

The gene (coxII) encoding subunit II of Rhodobacter sphaeroides cytochrome c oxidase (cytochrome aa3) has been isolated by screening a genomic DNA library in phage lambda with a probe derived from coxII of Paracoccus denitrificans. A 2-kb fragment containing coxII DNA was subcloned into the phage M13mp18 and the sequence determined. The 2-kb insert contains the entire coding region for coxII gene, including the ATG start codon and a TGA stop codon. The deduced amino acid (aa) sequence of subunit II of R. sphaeroides shows regions of substantial homology to the corresponding subunit of the bovine mitochondrial oxidase (63% overall) and P. denitrificans oxidase (68% overall). The postulated redox-active copper ion (CuA) binding site involving two Cys and two His residues (as well as an alternative Met residue) is conserved among these species, along with four invariant acidic aa residues (two Asp and two Glu) that may be involved in interactions with cytochrome c, and a region of aromatic residues (Tyr-Gln-Trp-Tyr-Trp-Gly-Tyr-Glu-Tyr) which is postulated to play a role in electron transfer. Hydropathy profile analysis suggests that while the bovine COXII secondary structure contains two transmembrane helices, the R. sphaeroides subunit II has a third such helix that may function as part of a signal sequence, as suggested for P. denitrificans.
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PMID:The gene encoding cytochrome c oxidase subunit II from Rhodobacter sphaeroides; comparison of the deduced amino acid sequence with sequences of corresponding peptides from other species. 164 8

The maternally inherited [exn-5] mutant of Neurospora crassa is characterized by its slow-growth rate and deficiency of cytochrome aa3 relative to wild-type strains. We have determined the DNA sequence of the COXI and COXII genes of the mutant, which encode subunits 1 and 2 of cytochrome c oxidase, respectively. No changes in the DNA sequence of the COXI gene relative to the corresponding wild-type gene were found. In the region of the COXII gene we found two alterations, one a C to T transition eight base pairs upstream of the coding sequence and the second within the coding sequence for subunit 2 affecting amino acid 27 of the precursor polypeptide (amino acid 15 of the mature polypeptide). The altered codon in [exn-5] specifies an isoleucine residue rather than the wild-type threonine residue. The corresponding position in subunit 2 sequences of all other organisms examined is conserved either as a threonine or a serine residue. Thus, we consider it likely that the mutation directly affecting the coding sequence of the polypeptide is responsible for the [exn-5] phenotype. Analysis of serially passaged heterokaryons constructed between wild-type and [exn-5] shows that both mutations segregate with the [exn-5] phenotype. Examination of mitochondrial translation products in [exn-5] revealed a deficiency of subunit 2, as well as the presence of a polypeptide that corresponds to a previously described precursor of subunit 1 that accumulates in a COXI mutant of N. crassa, [mi-3]. We propose possible relationships between [exn-5], [mi-3], and the nuclear su-1[mi-3] allele, which suppresses both mutations.
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PMID:Alteration of the cytochrome c oxidase subunit 2 gene in the [exn-5] mutant of Neurospora crassa. 165 11

Determination of sequences from the nine regions separating the large genes in the 19-kbp mitochondrial DNA from Torulopsis glabrata has led to the identification of 23 tRNA genes and to the recognition of two types of short repeated sequence implicated in mitochondrial genome expression. The two short repeated sequences are a nonanucleotide motif, 5'-TATAAGTAA-3' and a dodecanucleotide motif, 5'-TATAATATTCTT-3'. By RNA sequence determination it has been found that primary transcripts of the small and large rRNAs commence at the 3' penultimate adenine of the nonanucleotide sequence. This motif has also been found in the DNA sequence upstream from f-methionine, phenylalanine, leucine, tyrosine and glycine tRNAs, cytochrome oxidase subunit 2 and ATPase subunit 9. The dodecanucleotide sequence is found at least once in each of the nine regions between the large genes. Determination of the 3' ends of the small and large rRNAs has shown their location to be 8 and 23 nucleotides downstream from the dodecanucleotide sequence. This motif is thought to be involved in signalling processing of polycistronic transcripts. Such transcripts are invoked to account for the production of mRNAs for cytochrome b, cytochrome oxidase subunits 1 and 3, and the joint mRNA for ATPase subunits 8 and 6 genes that lack an adjacent upstream nonanucleotide transcription initiation signal sequence. Processing of polycistronic transcripts at tRNA sequences is also implicated in the formation of mature mRNAs. From the position of tRNA genes relative to the nonanucleotide motif it appears that clusters of these genes are co-transcribed with downstream sequences for cytochrome oxidase subunits 1 and 3.
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PMID:Location of transcriptional control signals and transfer RNA sequences in Torulopsis glabrata mitochondrial DNA. 404 Apr 62

The nucleotide sequence of the cytochrome oxidase subunit 2 (COX2) gene has been obtained from cloned mitochondrial DNA segments of Neurospora crassa. The coding sequences have been identified on the basis of protein sequence homology with the subunit 2 of cytochrome oxidase from yeast and man. The postulated precursor of the N. crassa subunit 2 protein is 250 amino acids long, with a molecular weight of 28,700. As in the tRNA and rRNA genes, the subunit 2 gene is flanked by G + C-rich palindromic sequences, which are highly conserved in N. crassa mitochondria. Three major transcripts have been detected by Northern blot hybridization. A transcript of 1100 bases is tentatively considered the fully processed mRNA. Furthermore, S1 nuclease protection experiments have revealed that the putative subunit 2 mRNA has a 330 nucleotide long 5' leader sequence.
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PMID:Cytochrome oxidase subunit 2 gene in Neurospora crassa mitochondria. 631 89

The maize NCS6 mitochondrial mutation is a partial deletion of the cytochrome oxidase subunit 2 gene (cox2) that survives heteroplasmically in the plant. Mutant mitochondria segregate from normal mitochondria during somatic development giving rise to defective sectors on the plants, including areas of kernel abortion on the ears. Embryos from NCS6 kernels can be rescued by tissue culture. Slowly growing Type II callus derived from one of these embryos has been shown by PCR analysis to be homoplasmic for the mutation, carrying only the defective mitochondrial cox2 gene. Most of the rescued embryos were heteroplasmic for normal and mutant genes and heteroplasmy was maintained in the callus cultures. However, when suspension cultures were initiated from heteroplasmic calli, normal cells were shown to have a selective advantage. When the homoplasmic cox2 mutant callus cultures were placed on regeneration medium, plantlets did not regenerate. Heteroplasmic calli were capable of regeneration under the same conditions. These studies suggest that the functioning of mitochondrial cytochrome oxidase is not essential for growth as callus, but is required for the differentiation and development of plants.
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PMID:Rescue of a maize mitochondrial cytochrome oxidase mutant by tissue culture. 784 53

Ascaridoid nematodes parasitize the gastrointestinal tract of vertebrate definitive hosts and are represented by more than 50 described genera. We used 582 nucleotides (83% of the coding sequence) of the mitochondrial gene cytochrome oxidase subunit 2, in combination with published small- and large-subunit nuclear rDNA sequences (2,557 characters) and morphological data (20 characters), to produce a phylogenetic hypothesis for representatives of this superfamily. This combined evidence phylogeny strongly supported clades that, with 1 exception, were consistent with Fagerholm's 1991 classification. Parsimony mapping of character states on the combined evidence tree was used to develop hypotheses for the evolution of morphological, life history, and amino acid characters. This analysis of character evolution revealed that certain key features that have been used by previous workers for developing taxonomic and evolutionary hypotheses represent plesiomorphic states. Cytochrome oxidase subunit 2 nucleotides show a strong compositional bias to A+T and a substitution bias to thymine. These biases are most apparent at third positions of codons and 4-fold degenerate sites, which is consistent with the nonrandom substitution pattern of A+T pressure. Despite nucleotide bias, cytochrome oxidase amino acid sequences show conservation and retention of critical functional residues, as inferred from comparisons to other organisms.
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PMID:Phylogeny of the Ascaridoidea (Nematoda: Ascaridida) based on three genes and morphology: hypotheses of structural and sequence evolution. 1078 May 61

Traumatic brain injury (TBI) is documented to have detrimental effects on CNS metabolism, including alterations in glucose utilization and the depression of mitochondrial oxidative phosphorylation. Studies on mitochondrial metabolism have also provided evidence for reduced activity of the cytochrome oxidase complex of the electron transport chain (complex IV) after TBI and an immediate (lhr) reduction in mitochondrial state 3 respiratory rate, which can persist for up to 14 days postinjury. Using differential display methods to screen for differences in gene expression, we have found that cytochrome c oxidase II (COII), a mitochondrial encoded subunit of complex IV, is upregulated following TBI. Since COII carries a binding site for cytochrome c in the respiratory chain, and since it is required for the passage of chain electrons to molecular oxygen, driving the production of ATP, we hypothesized that metabolic dysfunction resulting from TBI alters COII gene expression directly, perhaps influencing the synaptic plasticity that occurs during postinjury recovery processes. To test this hypothesis, we documented COII mRNA expression and complex IV (cytochrome c oxidase) functional activity at 7 days postinjury, focusing on the long-term postinjury period most closely associated with synaptic reorganization. Both central fluid percussion TBI and combined TBI and bilateral entorhinal cortical lesion were examined. At 7 days survival, differential display, RT-PCR, and Northern blot analysis of hippocampal RNA from both TBI and combined insult models showed a significant induction of COII mRNA. This long-term elevation in COII gene expression was supported by increases in COII immunobinding. By contrast, cytochrome oxidase histochemical activity within tissue sections from injured brains suggested a reduction of complex IV activity within the TBI cases, but not within animals subjected to the combined insult. These differences in cytochrome c oxidase activity were supported by in vitro assay of complex IV using cerebral cortical and hippocampal tissues. Our present results support the hypothesis that COII is selectively vulnerable to TBI and that COII differences may indicate the degree of metabolic dysfunction induced by different pathologies. Taken together, such data will better define the role of metabolic function in long-term recovery after TBI.
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PMID:Traumatic brain injury-induced changes in gene expression and functional activity of mitochondrial cytochrome C oxidase. 1168 99

Although the physiological role of plant mitochondria is thought to vary in different tissues at progressive stages of development, there has been little documentation that the complement of mitochondrial proteins is altered in different plant organs. Because the phenomenon of cytoplasmic male sterility suggests an unusual function for mitochondria in floral buds, we examined the tissue-specific expression of mitochondrial proteins in petunia buds at several stages of development, using both fertile and cytoplasmic male sterile plants. On tissue prints of cryostat-sectioned buds, antibodies recognizing subunit A of the mitochondrial ATPase (ATPA) localized very differently from antibodies recognizing subunit II of the cytochrome oxidase (COXII), which indicated that mitochondria in the same tissue could differentially express mitochondrially encoded proteins. The petunia cytoplasmic male sterility-associated fused (pcf) gene encodes a protein that colocalized with ATPA and the nuclear-encoded mitochondrial alternative oxidase (AOA) in sporogenous tissues, where little COXII protein was found. These overlapping and differential localization patterns may provide clues to the molecular mechanism of cytoplasmic male sterility.
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PMID:Tissue-Specific Protein Expression in Plant Mitochondria. 1224 22


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