Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P06889 (Mol)
 630,302 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

We have determined and compared the promoter, coding, and intronic sequences of the urate oxidase (Uox) gene of various primate species. Although we confirm the previous observation that the inactivation of the gene in the clade of the human and the great apes results from a single CGA to TGA nonsense mutation in exon 2, we find that the inactivation in the gibbon lineage results from an independent nonsense mutation at a different CGA codon in exon 2 or from either one-base deletion in exon 3 or one-base insertion in exon 5, contrary to the previous claim that the cause is a 13-bp deletion in exon 2. We also find that compared with other organisms, the primate functional Uox gene is exceptional in terms of usage of CGA codons which are prone to TGA nonsense mutations. Nevertheless, we demonstrate rather strong selective constraint against nonsynonymous sites of the functional Uox gene and argue that this observation is consistent with the fact that the Uox gene is unique in the genome and evolutionarily conserved not only among animals but also among eukaryotes. Another finding that there are a few substitutions in the cis-acting element or CAAT-box (or both) of primate functional Uox genes may explain the lowered transcriptional activity. We suggest that although the inactivation of the hominoid Uox gene was caused by independent nonsense or frameshift mutations, the gene has taken a two-step deterioration process, first in the promoter and second in the coding region during primate evolution. It is also argued that the high concentration of uric acid in the blood of humans and nonhuman primates has developed molecular coevolution with the xanthine oxidoreductase in purine metabolism. However, it remains to be answered whether loss of Uox activity in hominoids is related to protection from oxidative damage and the prolonged life span.
Mol Biol Evol 2002 May
PMID:Loss of urate oxidase activity in hominoids and its evolutionary implications. 1196 Oct 98

A silkworm mutant, oq, has translucent larval skin because it is deficient in xanthine dehydrogenase (XDH) activity and is unable to synthesize uric acid, which is normally accumulated in the larval epidermis and makes the skin white and opaque. Two XDH bands were found in zymograms of the silkworm fat body: an intense band (XDHalpha) and a faint one (XDHbeta). The oq mutant lacks only XDHalpha, which seemed to be the major source of XDH activity in the fat body. An 8-bp deletion found in BmXDH1, a silkworm XDH gene, generates a premature stop codon. The resulting truncated BmXDH1 protein lacks three molybdenum cofactor-binding domains necessary for enzyme activity. BmXDH2, the other XDH gene, does not show any apparent deficiencies. BmXDH1 expressed in yeast cells yielded an activity band with the same mobility as that of XDHalpha in zymograms. BmXDH1 of the oq mutant did not yield active XDH in yeast, while the activity was restored by filling in the deleted sequence. These results showed that BmXDH1 deletion in the oq mutant is responsible for the absence of significant XDH activity, resulting in the translucent larval skin of the mutant phenotype.
Insect Biochem Mol Biol 2002 Jun
PMID:A deleted portion of one of the two xanthine dehydrogenase genes causes translucent larval skin in the oq mutant of the silkworm (Bombyx mori). 1202 Aug 33

The iron chelator deferoxamine has been reported to inhibit both xanthine oxidase (XO) and xanthine dehydrogenase activity, but the relationship of this effect to the availability of iron in the cellular and tissue environment remains unexplored. XO and total xanthine oxidoreductase activity in cultured V79 cells was increased with exposure to ferric ammonium sulfate and inhibited by deferoxamine. Lung XO and total xanthine oxidoreductase activities were reduced in rats fed an iron-depleted diet and increased in rats supplemented with iron, without change in the ratio of XO to total oxidoreductase. Intratracheal injection of an iron salt or silica-iron, but not aluminum salts or silica-zinc, significantly increased rat lung XO and total xanthine oxidoreductase activities, immunoreactive xanthine oxidoreductase, and the concentration of urate in bronchoalveolar fluid. These results suggest the possibility that the production of uric acid, a major chelator of iron in extracellular fluid, is directly influenced by iron-mediated regulation of the expression and/or activity of its enzymatic source, xanthine oxidase.
Am J Physiol Lung Cell Mol Physiol 2002 Sep
PMID:Iron regulates xanthine oxidase activity in the lung. 1216 76

Human molybdenum cofactor deficiency is a rare and devastating autosomal-recessive disease for which no therapy is known. The absence of active sulfite oxidase-a molybdenum cofactor-dependent enzyme-results in neonatal seizures and early childhood death. Most patients harbor mutations in the MOCS1 gene, whose murine homolog was disrupted by homologous recombination with a targeting vector. As in humans, heterozygous mice display no symptoms, but homozygous animals die between days 1 and 11 after birth. Biochemical analyis of these animals shows that molydopterin and active cofactor are undetectable. They do not possess any sulfite oxidase or xanthine dehydrogenase activity. No organ abnormalities were observed and the synaptic localization of inhibitory receptors, which was found to be disturbed in molybdenum cofactor deficient-mice with a Gephyrin mutation, appears normal. MOCS1(-/-) mice could be a suitable animal model for biochemical and/or genetic therapy approaches.
Hum Mol Genet 2002 Dec 15
PMID:Molybdenum cofactor-deficient mice resemble the phenotype of human patients. 1247 Oct 57

Normal silkworms (Bombyx mori) have opaque larval skin due to uric acid accumulation in the epidermis while a mutant, og, is translucent owing to a deficiency in xanthine dehydrogenase (XDH), which synthesizes uric acid. Molybdenum cofactor (MoCo) sulfurase is responsible for XDH activation in various organisms. A silkworm MoCo sulfurase gene was cloned and found to be on the og locus, whose mutant alleles, og(k) and og(t), show premature stop codons, proving that og is the MoCo sulfurase gene. It was observed that a miniature inverted-repeat transposable element (MITE), named Organdy, when inserted in an og(t) mutant allele exon, causes unstable splicing of a downstream intron leading to incomplete open reading frames.
Insect Biochem Mol Biol 2003 Apr
PMID:Mutations of the silkworm molybdenum cofactor sulfurase gene, og, cause translucent larval skin. 1265 Jun 90

Acute lung injury (ALI) is characterized by increased alveolar cytokines, inflammatory cell infiltration, oxidative stress, and alveolar cell apoptosis. Previous work suggested that xanthine oxidoreductase (XOR) may contribute to oxidative stress in ALI as a product of the vascular endothelial cell. We present evidence that cytokine induced lung inflammation and injury involves activation of XOR in the newly recruited mononuclear phagocytes (MNP). We found that XOR was increased predominantly in the MNP that increase rapidly in the lungs of rats that develop ALI following intratracheal cytokine insufflation. XOR was recovered from the MNP largely converted to its oxygen radical generating, reversible O-form, and alveolar MNP exhibited increased oxidative stress as evidenced by increased nitrotyrosine staining. Cytokine insufflation also increased alveolar cell apoptosis. A functional role for XOR in cytokine-induced inflammation was demonstrated when feeding rats two different XOR inhibitors, tungsten and allopurinol, decreased MNP XOR induction, nitrotyrosine staining, inflammatory cell infiltration, and alveolar cell apoptosis. Transfer of control or allopurinol treated MNP into rat lungs confirmed a specific role for MNP XOR in promoting lung inflammation. These data indicate that XOR can contribute to lung inflammation by its expression and conversion in a highly mobile inflammatory cell population.
Am J Respir Cell Mol Biol 2004 Apr
PMID:Mononuclear phagocyte xanthine oxidoreductase contributes to cytokine-induced acute lung injury. 1451 76

Substitution therapies for orphan genetic diseases, including enzyme replacement methods, are frequently hampered by the limited availability of the required therapeutic substance. We describe the isolation of a pterin intermediate from bacteria that was successfully used for the therapy of a hitherto incurable and lethal disease. Molybdenum cofactor (Moco) deficiency is a pleiotropic genetic disorder characterized by the loss of the molybdenum-dependent enzymes sulphite oxidase, xanthine oxidoreductase and aldehyde oxidase due to mutations in Moco biosynthesis genes. An intermediate of this pathway-'precursor Z'-is more stable than the cofactor itself and has an identical structure in all phyla. Thus, it was overproduced in the bacterium Escherichia coli, purified and used to inject precursor Z-deficient knockout mice that display a phenotype which resembles that of the human deficiency state. Precursor Z-substituted mice reach adulthood and fertility. Biochemical analyses further suggest that the described treatment can lead to the alleviation of most symptoms associated with human Moco deficiency.
Hum Mol Genet 2004 Jun 15
PMID:Rescue of lethal molybdenum cofactor deficiency by a biosynthetic precursor from Escherichia coli. 1511 59

Tissues of kuruma shrimp Marsupenaeus japonicus Bate (5.7+/-1.1 g) reared in salinities of 18, 26, 34 and 42 were examined for levels of nucleotide-related compounds, ammonia, urea and uric acid, and activities of xanthine dehydrogenase (XDH), xanthine oxidase (XOD) and uricase. Levels of total nucleotide-related compounds, including xanthine and hypoxanthine, in gill increased directly with salinity, whereas these same levels in hepatopancreas were inversely related with salinity. Hemolymph ammonia, urea and uric acid levels, and epidermal ammonia, urea and uric acid levels increased directly with salinity, whereas hepatopancreas ammonia and uric acid and gill uric acid levels were inversely related to salinity. Activities of XDH and XOD in hepatopancreas increased directly with salinity level, whereas no significant difference of uricase activity in hepatopancreas was observed among the four salinities. It is concluded M. japonicus exhibited uricogenesis and uricolysis, and an increase of uricogenesis occurred for the shrimp under hyper-osmotic conditions (salinity of 42). Uric acid produced in the hepatopancreas was transported and accumulated in the epidermis, and removed along with the spongy connective tissue at the time of molting.
Comp Biochem Physiol B Biochem Mol Biol 2004 Jul
PMID:Increase of uricogenesis in the kuruma shrimp Marsupenaeus japonicus reared under hyper-osmotic conditions. 1525 73

The isc and suf operons in Escherichia coli represent alternative genetic systems optimized to mediate the essential metabolic process of iron-sulfur cluster (Fe-S) assembly under basal or oxidative-stress conditions, respectively. Some of the proteins in these two operons share strong sequence homology, e.g. the cysteine desulfurases IscS and SufS, and presumably play the same role in the oxygen-sensitive assembly process. However, other proteins in these operons share no significant homology and occur in a mutually exclusive manner in Fe-S assembly operons in other organisms (e.g. IscU and SufE). These latter proteins presumably play distinct roles adapted to the different assembly mechanisms used by the two systems. IscU has three invariant cysteine residues that function as a template for Fe-S assembly while accepting a sulfur atom from IscS. SufE, in contrast, does not function as an Fe-S assembly template but has been suggested to function as a shuttle protein that uses a persulfide linkage to a single invariant cysteine residue to transfer a sulfur atom from SufS to an alternative Fe-S assembly template. Here, we present and analyze the 2.0A crystal structure of E.coli SufE. The structure shows that the persulfide-forming cysteine occurs at the tip of a loop with elevated B-factors, where its side-chain is buried from solvent exposure in a hydrophobic cavity located beneath a highly conserved surface. Despite the lack of sequence homology, the core of SufE shows strong structural similarity to IscU, and the sulfur-acceptor site in SufE coincides with the location of the cysteine residues mediating Fe-S cluster assembly in IscU. Thus, a conserved core structure is implicated in mediating the interactions of both SufE and IscU with the mutually homologous cysteine desulfurase enzymes present in their respective operons. A similar core structure is observed in a domain found in a variety of Fe-S cluster containing flavoenzymes including xanthine dehydrogenase, where it also mediates interdomain interactions. Therefore, the core fold of SufE/IscU has been adapted to mediate interdomain interactions in diverse redox protein systems in the course of evolution.
J Mol Biol 2004 Nov 19
PMID:The SufE sulfur-acceptor protein contains a conserved core structure that mediates interdomain interactions in a variety of redox protein complexes. 1552 4

The xanthine oxidases and dehydrogenases are among the most conserved enzymes in all living kingdoms. They contain the molybdopterin cofactor Moco. We show here that in the fungi, in addition to xanthine dehydrogenase, a completely different enzyme is able to catalyse the oxidation of xanthine to uric acid. In Aspergillus nidulans this enzyme is coded by the xanA gene. We have cloned the xanA gene and determined its sequence. A deletion of the gene has the same phenotype as the previously known xanA1 miss-sense mutation. Homologues of xanA exist only in the fungal kingdom. We have inactivated the cognate gene of Schizosaccharomyces pombe and this results in strongly impaired xanthine utilization as a nitrogen source. We have shown that the Neurospora crassa homologue is functionally equivalent to xanA. The enzyme coded by xanA is an alpha-ketoglutarate- and Fe(II)-dependent dioxygenase which shares a number of properties with other enzymes of this group. This work shows that only in the fungal kingdom, an alternative mechanism of xanthine oxidation, not involving Moco, has evolved using the dioxygenase scaffold.
Mol Microbiol 2005 Jul
PMID:Convergent evolution of hydroxylation mechanisms in the fungal kingdom: molybdenum cofactor-independent hydroxylation of xanthine via alpha-ketoglutarate-dependent dioxygenases. 1594 66


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