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)

In R. capsulatus synthesis and activity of the molybdenum and the alternative nitrogenase is controlled at three levels by the environmental factors ammonium, molybdenum, light, and oxygen. At the first level, transcription of the nifA1, nifA2, and anfA genes--which encode the transcriptional activators of all other nif and anf genes, respectively--is controlled by the Ntr system in dependence on ammonium availability. Mutations in ginB (coding for the signal transduction protein PII) result in significant expression of nifA and anfA in the presence of ammonium. In contrast to GlnB, the PII-paralogue GlnK is not involved in the Ntr signal transduction mechanism. In addition to ammonium control, transcription of anfA is inhibited by traces of molybdenum via the molybdate-dependent repressor proteins MopA and MopB. At the second level of regulation, activity of NifA1, NifA2, and AnfA is inhibited by ammonium in an NtrC-independent manner. This post-translational ammonium control of NifA activity is partially released in the absence of GlnK, and completely abolished in a glnB/glnK double mutant. In contrast, AnfA activity is still inhibited by ammonium in the glnB/glnK mutant background. At the third level of regulation, both GlnB and GlnK as well as the (methyl)-ammonium transporter AmtB are involved in ammonium control of the DraT/DraG system, which mediates reversible ADP-ribosylation of both nitrogenase reductases (NifH and AnfH) in response to changes in ammonium availability or light intensity. Most remarkably, in a glnB/glnK double mutant ammonium control of the molybdenum (but not of the alternative) nitrogenase is completely relieved, leading to synthesis of active nitrogenase in the presence of high concentrations of ammonium.
J Mol Microbiol Biotechnol 2002 May
PMID:Regulation of nitrogen fixation in the phototrophic purple bacterium Rhodobacter capsulatus. 1193 54

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

Multifocal myocardial necrosis (MMN) is an unusual cardiomyopathy of childhood, characterized by multiple patchy areas of myocardial fiber necrosis/fibrosis involving mainly the middle part of the left ventricle, but also, to a lesser extent, the right ventricle and the atria. These necrotic lesions are isolated and are not accompanied by an inflammatory reaction or vascular alterations. They are responsible for acute cardiac failure. MMN lesions are observed in various pathologic conditions including cystic fibrosis of the pancreas, pancreatic lipomatous hypoplasia/atrophy, malnutrition due to extensive intestinal resection with subsequent total parenteral feeding, and in Keshan disease. MMN is the main and the most characteristic feature of Keshan disease, an endemic and idiopathic condition affecting Chinese rural children. The causes and mechanisms of MMN presently are unknown. However, the presence of similar cardiac lesions in such different pathological conditions suggests the role of a selective deficiency of a hypothetical extrinsic factor (selenium, molybdenum iodide, other), probably crucial for the metabolism of the myocardial fiber.
Pediatr Pathol Mol Med
PMID:Multifocal myocardial necrosis: a distinctive cardiac lesion in cystic fibrosis, lipomatous pancreatic atrophy, and Keshan disease. 1255

Dimethyl sulphide dehydrogenase catalyses the oxidation of dimethyl sulphide to dimethyl sulphoxide (DMSO) during photoautotrophic growth of Rhodovulum sulfidophilum. Dimethyl sulphide dehydrogenase was shown to contain bis(molybdopterin guanine dinucleotide)Mo, the form of the pterin molybdenum cofactor unique to enzymes of the DMSO reductase family. Sequence analysis of the ddh gene cluster showed that the ddhA gene encodes a polypeptide with highest sequence similarity to the molybdopterin-containing subunits of selenate reductase, ethylbenzene dehydrogenase. These polypeptides form a distinct clade within the DMSO reductase family. Further sequence analysis of the ddh gene cluster identified three genes, ddhB, ddhD and ddhC. DdhB showed sequence homology to NarH, suggesting that it contains multiple iron-sulphur clusters. Analysis of the N-terminal signal sequence of DdhA suggests that it is secreted via the Tat secretory system in complex with DdhB, whereas DdhC is probably secreted via a Sec-dependent mechanism. Analysis of a ddhA mutant showed that dimethyl sulphide dehydrogenase was essential for photolithotrophic growth of Rv. sulfidophilum on dimethyl sulphide but not for chemo-trophic growth on the same substrate. Mutational analysis showed that cytochrome c2 mediated photosynthetic electron transfer from dimethyl sulphide dehydrogenase to the photochemical reaction centre, although this cytochrome was not essential for photoheterotrophic growth of the bacterium.
Mol Microbiol 2002 Jun
PMID:Molecular analysis of dimethyl sulphide dehydrogenase from Rhodovulum sulfidophilum: its place in the dimethyl sulphoxide reductase family of microbial molybdopterin-containing enzymes. 1206 45

The bicistronic MOCS1 gene encodes two enzymatic activities that are necessary for the biosynthesis of the molybdenum cofactor (MoCo). Mutations in either of the two consecutive open reading frames are responsible for the majority of MoCo deficiency cases and result in a complementation group A phenotype. Two cDNA sequences have been described, which differ in the 5' sequence and encode for two forms of the protein MOCS1A with variable N-terminal sequences. We have reinvestigated the corresponding region by means of cDNA analysis and databank searches. This revealed three different splice variants, including two mutually exclusive first exons and a facultative intron. All three forms can be found in eight different human tissues in a constant ratio, which excludes tissue specificity of the different isoforms.
Mol Genet Metab 2002 Aug
PMID:The bicistronic MOCS1 gene has alternative start codons on two mutually exclusive exons. 1220 40

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

Optical absorption studies of phthalocyanines (Pc-s) in borate glass matrix have been reported for the first time. Measurements have been done corresponding to photon energies between 1.1 and 6.2 eV for free base, manganese, iron, nickel, molybdenum, cobalt and copper phthalocyanines. Several new discrete transitions are observed in the UV-vis region of the spectra in addition to a strong continuum component of absorption in the IR region. Values of some of the important optical constants viz. absorption coefficient (alpha), molar extinction coefficient (epsilon), absorption cross-section (sigma(a)), band width (delta lambda), electric dipole strength (q2) and oscillator strength (f) for the relevant electronic transitions are also presented. All the data reported for Pc-s in the new matrix have been compared with those corresponding to solution, vapor and thin film media.
Spectrochim Acta A Mol Biomol Spectrosc 2003 Jan 01
PMID:NIR to UV absorption spectra and the optical constants of phthalocyanines in glassy medium. 1250 41

ModE is a bacterial transcriptional regulator that orchestrates many aspects of molybdenum metabolism by binding to specific DNA sequences in a molybdate-dependent fashion. We present the crystal structure of Escherichia coli ModE in complex with molybdate, which was determined at 2.75A from a merohedrally twinned crystal (twin fraction approximately 0.30) with space group P4(3). We now have structures of ModE in both its "switched on" (ligand-bound) and "switched off" (apo) states. Comparison with the apo structure shows that ligand binding leads to extensive conformational changes not only in the molybdate-binding domain, but also in the DNA-binding domain. The most obvious difference is the loss of the pronounced asymmetry between the two chains of the ModE dimer, which had been a characteristic property of the apo structure. Another major change concerns the relative orientation of the two DNA-interacting winged helix-turn-helix motifs. Manual docking of an idealized DNA structure suggests that this conformational change should improve DNA binding of the activated molybdate-bound ModE.
J Mol Biol 2003 Feb 21
PMID:Crystal structure of activated ModE reveals conformational changes involving both oxyanion and DNA-binding domains. 1258 38

1D and 2D 1H and 13C NMR spectra of the assumed [MoO(4)(TEA)](2-) complex recorded in DMSO at variable temperatures clearly indicate one free and two bound hydroxyethyl arms. The free arm of the ligand readily exchanges with the two metal-bound arms. Under such conditions the triethanolamine (TEA) acts as a bidentate ligand. The presence of water accelerates the exchange, which at higher water content involves the free ligand too. In organic solvents the binding strength of the hydroxo groups to the molybdenum is weaker than that of the water molecules. A plausible structure is confirmed by 14N, 17O and 95Mo measurements and an exchange mechanism based on the existence of an eight-membered relatively rigid chelate ring is suggested.
Spectrochim Acta A Mol Biomol Spectrosc 2003 Jul
PMID:Equilibria of mononuclear oxomolybdenum(VI) complexes of triethanolamine. A multinuclear dynamic magnetic resonance study of structure and exchange mechanisms. 1278 53

The structure of the yeast DNA-dependent RNA polymerase I (RNA Pol I), prepared by cryo-negative staining, was studied by electron microscopy. A structural model of the enzyme at a resolution of 1.8 nm was determined from the analysis of isolated molecules and showed an excellent fit with the atomic structure of the RNA Pol II Delta4/7. The high signal-to-noise ratio (SNR) of the stained molecular images revealed a conformational flexibility within the image data set that could be recovered in three-dimensions after implementation of a novel strategy to sort the "open" and "closed" conformations in our heterogeneous data set. This conformational change mapped in the "wall/flap" domain of the second largest subunit (beta-like) and allows a better accessibility of the DNA-binding groove. This displacement of the wall/flap domain could play an important role in the transition between initiation and elongation state of the enzyme. Moreover, a protrusion was apparent in the cryo-negatively stained model, which was absent in the atomic structure and was not detected in previous 3D models of RNA Pol I. This structure could, however, be detected in unstained views of the enzyme obtained from frozen hydrated 2D crystals, indicating that this novel feature is not induced by the staining process. Unexpectedly, negatively charged molybdenum compounds were found to accumulate within the DNA-binding groove, which is best explained by the highly positive electrostatic potential of this region of the molecule, thus, suggesting that the stain distribution reflects the overall surface charge of the molecule.
J Mol Biol 2003 Jun 20
PMID:Cryo-negative staining reveals conformational flexibility within yeast RNA polymerase I. 1279 80


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