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)

The complete nucleotide sequence of the Escherichia coli nik locus, which has been suggested to encode the specific transport system for nickel, has been determined. It was found to contain five overlapping open reading frames that form a single transcription unit. Deduced amino acid sequence of the nik operon shows that its five gene products, NikA to NikE, are highly homologous to components of oligopeptide- and dipeptide-binding protein-dependent transport systems from several Gram-negative and Gram-positive species. NikA represents the periplasmic binding protein, NikB and NikC are similar to integral membrane components of periplasmic permeases, and NikD and NikE possess typical ATP-binding domains that suggest their energy coupling role to the transport process. Insertion mutations in nik genes totally abolished the nickel-containing hydrogenase activity under nickel limitation and markedly altered the rate of nickel transport. Taken together, these data support the notion that the nik operon encodes a typical periplasmic binding-protein-dependent transport system for nickel.
Mol Microbiol 1993 Sep
PMID:The nik operon of Escherichia coli encodes a periplasmic binding-protein-dependent transport system for nickel. 793 31

We have used chemical modification analysis to probe the solution structure of the hairpin ribozyme. The modifying reagents dimethylsulfate, 1-cyclohexyl-N'-[2-(N-methylmorpholino) ethyl-carbodiimide-p-toluenesulfonate, kethoxal, diethylpyrocarbonate and (2,12-dimethyl-3,7,11,17- tetraazabicyclo [11.3.1]heptadeca-1(17),2,11,13,15-pentaenato) nickel(II) perchlorate were used to probe functional groups that participate in Watson-Crick and non-canonical base-pairs. Our results confirm the existence of four short helices (3 to 6 bp) within the ribozyme-substrate complex, and demonstrate that one intramolecular helix (helix 4) is comprised of three base-pairs rather than the previously suggested five. In the absence of magnesium, the ribozyme is observed to fold into its secondary structure. Upon addition of magnesium, a striking difference in chemical modification is observed, particularly at sites within the ribozyme's large internal loop (loop B) that are essential for catalytic function (bases 21 to 26). Moreover, magnesium-dependent folding clearly destabilizes an A-U base-pair in a region where a proposed bend is required to juxtapose the catalytically essential loops A and B. Upon addition of substrate, no changes are observed in the structure of helix 3, loop B or helix 4. However, strong protection of bases in the substrate-binding domain is observed, including those located across internal loop A. The modification data are consistent with the formation of a previously proposed tertiary structure motif within loop B that includes non-canonical G-A, A-U and A-A base-pairs, and that is identical with those identified by NMR analysis of loop E of 5 S rRNA and the sarcin/ricin loop of 28 S rRNA. Our results indicate that the hairpin ribozyme adopts a stable magnesium-dependent tertiary structure to which the substrate binds without inducing major conformational changes, and that substrate recognition is likely to involve non-canonical base-pairs between the ribozyme and substrate sequences adjacent to the cleavage site.
J Mol Biol 1994 Nov 18
PMID:Structure-mapping of the hairpin ribozyme. Magnesium-dependent folding and evidence for tertiary interactions within the ribozyme-substrate complex. 796 21

The data are reviewed on plasmid determinants controlling resistance of gram-negative bacteria to heavy metals. The structural and functional arrangement of operons determining resistance to copper, zinc, cadmium, cobalt, nickel, tellurites, and chromates is emphasized. The fields of use of the genetic potential of the bacteria resistant to metals in the modern biotechnological processes are envisaged.
Mol Gen Mikrobiol Virusol
PMID:[Resistance to metals determined by plasmids of gram-negative bacteria]. 806 83

From a library of 3000 Escherichia coli clones, each containing a single, chromosomally located luxAB transcriptional gene fusion, one clone was found in which luminescence increased in the presence of 1 to 50 ppm of NiSO4. A molecular analysis revealed that the insertion occurred within the celF gene of E. coli. This gene encodes the phospho-beta-glucosidase involved in cleavage of the sugars cellobiose, salicin and arbutin. Cloning and sequencing of DNA downstream of the celF gene revealed three open reading frames (potentially encoding polypeptides of 9.9, 14.1 and 28.5 kDa) that could be co-expressed with the celF gene and that may underlie the observed induction of the celF gene by nickel. A polypeptide of 26 kDa was produced when this region was placed under the control of the Ptac promoter. Moreover, this region was found to be directly adjacent to, and transcribed in the opposite orientation from, the katE gene of E. coli.
Mol Gen Genet 1994 Feb
PMID:A luxAB transcriptional fusion to the cryptic celF gene of Escherichia coli displays increased luminescence in the presence of nickel. 812 1

This report describes a Mn(2+)-enhanced, RGD-dependent adhesion technique for isolation of adult rat type II cells for immediate functional studies. Lung cells were dissociated by 30 U/ml porcine pancreatic elastase and 50 micrograms/ml trypsin instilled in the airways. Macrophages were selectively removed by adhesion on purified normal goat IgG-coated petri dishes. Type II cells were isolated by adhesion for 45 min, on ProNectin-F-coated dishes in the presence of 0.5 mM Mn2+. The adherent type II cells were then detached with 0.025% trypsin, 2 mM EDTA in Hepes-buffered saline, pH 7.4. The technique yielded 1.5 to 1.7 x 10(7) (n = 8) cells from a 150- to 200-g rat. Greater than 90% of the cells were pure type II cells as judged by tannic acid staining and immunostaining with monoclonal antibody 4AmAb, which recognizes pneumocin, a type II cell marker. The technique reduced the time required for cell isolation from the current 16 to 24 h to 2 to 2.5 h, using commonly available laboratory equipment and reagents. Cells isolated by the procedure were used to study cell adhesion and spreading on purified extracellular matrix components in the presence of different divalent cations. Mn2+, Co2+, Ni2+, and Mg2+ enhanced adhesion of freshly isolated type II cells to fibronectin and ProNectin-F, while Ca2+ did not promote type II cell adhesion on these substrata. RGDS peptide at 1 mg/ml concentration inhibited the divalent cation-enhanced cell adhesion.
Am J Respir Cell Mol Biol 1994 Apr
PMID:A Mn(2+)-enhanced, RGD-dependent adhesion technique for isolation of adult rat type II alveolar epithelial cells for immediate functional studies. 813 51

When Chinese hamster ovary cells were treated with ultraviolet (UV) light or methyl methanesulfonate (MMS), a large number of DNA strand breaks could be detected by alkaline elution. These strand breaks gradually disappeared if the treated cells were allowed to recover in a drug-free medium. The presence of nickel or arsenite during the recovery incubation retarded the disappearance of UV-induced strand breaks, whereas the disappearance of MMS-induced strand breaks was retarded by the presence of arsenite or of luminol, a new inhibitor for poly(ADP-ribose) synthetase. Luminol, however, had no apparent effect on the repair of UV-induced DNA strand breaks, and nickel had no effect on the repair of MMS-induced DNA strand breaks. When UV- or MMS-treated cells were incubated in cytosine arabinofuranoside (AraC) plus hydroxyurea (HU), a large amount of low molecular weight DNA was detected by alkaline sucrose sedimentation. The molecular weight of these DNAs increased if the cells were further incubated in a drug-free medium. This rejoining of breaks in cells pretreated with UV plus AraC and HU was inhibited by nickel and by arsenite, but not by luminol. The rejoining of breaks in cells pretreated with MMS plus AraC and HU was inhibited by luminol and by arsenite, but not by nickel. These results suggest that different enzymes may be used in DNA resynthesis and/or ligation during the repairing of UV- and MMS-induced DNA strand breaks, and that nickel, luminol, and arsenite may have differential inhibitory effects on these enzymes.
Environ Mol Mutagen 1994
PMID:Differential effects of luminol, nickel, and arsenite on the rejoining of ultraviolet light and alkylation-induced DNA breaks. 814 98

The amino acids that comprise the ligand binding sites of adenosine receptors have not been identified. Adenosine and its agonist analogues differ from ligands for the well studied biogenic amine receptors and rhodopsin in that the adenosine receptor agonists are larger, contain a ribose moiety, and are uncharged at physiological pH. Thus, the locations of the ligand binding pockets of the adenosine receptors could differ significantly from those of the biogenic amine receptors. This report describes the characterization of a purification-amenable truncated mutant of the canine A2a adenosine receptor and demonstrates that neither the long carboxyl-terminal tail nor the glycosidic moiety appears to be required for ligand binding. The dog thyroid A2a adenosine receptor cDNA (RDC8) was subcloned into the mammalian expression vector pCMV4. A mutant A2a construct, in which six histidines replaced residues 310-412 as the carboxyl terminus of the protein, also was prepared. When overexpressed transiently in COS M6 cells, the wild-type and mutant A2a receptors exhibited similar 2-[p-(2-[3H]carboxyethyl)phenylethylamino]-5'-N- ethylcarboxamidoadenosine saturation binding and competition curve profiles. The following biochemical techniques confirmed that the COS M6 cells were transcribing and translating A2a receptors of the expected molecular masses: (a) immunoblotting with an antipeptide antibody directed against the putative carboxyl-terminal side of the second extracellular loop (Tyr155-Val172) of the canine A2a adenosine receptor, (b) photoaffinity labeling with the A2a-selective agonist 125I-2-[4-[2-[2-[(4-azidophenyl)methylcarbonylamino] ethylaminocarbonyl]ethyl]phenyl]ethylamino-5'-N-ethylcarboxamidoad enosine (125I-azido-PAPA-APEC), and (c) partial purification of the hexahistidine-tagged receptor on Ni2+.nitrilotriacetic acid resin. A presumed A2a receptor (44 kDa) from rabbit striatal membranes also was detected with the antisera against amino acids Tyr155-Val172 of the RDC8 receptor. Not only could the mutant A2a receptor be photolabeled specifically with 125I-azido-PAPA-APEC but so too could unglycosylated A2a receptors (i.e., from tunicamycin-treated COS M6 cells), either full length or truncated. In all of these cases, photolabeling was attenuated by both agonist and antagonist competitors.
Mol Pharmacol 1994 May
PMID:A carboxyl-terminally truncated mutant and nonglycosylated A2a adenosine receptors retain ligand binding. 819 Jan 3

The effect of various metals and regucalcin, a calcium-binding protein isolated from rat liver cytosol, on (Ca(2+)-Mg2+)-ATPase activity in the plasma membranes of rat liver was investigated. Of various metals (Zn2+, Cu2+, Ni2+, Mn2+, Co2+ and Al3+; 100 microM as a final concentration), Mn2+ and Co2+ increased markedly (Ca(2+)-Mg2+)-ATPase activity, while other metals had no effect. When Ca2+ was not added into enzyme reaction mixture, Mn2+ and Co2+ (25-100 microM) did not significantly increase the enzyme activity, indicating that heavy metals act on Ca(2+)-stimulated phosphorylation of the enzyme. Meanwhile, regucalcin (0.25-1.0 microM) caused a remarkable elevation of (Ca(2+)-Mg2+)-ATPase activity. This increase was not inhibited by the presence of 100 microM vanadate, although the effects of Mn2+ and Co2+ (100 microM) were inhibited by vanadate. Also, the inhibition of the Mn2+ and Co2+ effects by vanadate was not seen in the presence of regucalcin. Moreover, regucalcin (0.5 microM) increased significantly the enzyme activity in the absence of Ca2+. This effect of regulcalcin was not altered by increasing concentrations of Ca2+ added, indicating that the regucalcin effect does not depend on Ca2+. The present results suggest that regucalcin activates directly (Ca(2+)-Mg2+)-ATPase in liver plasma membranes, and that the activation is not involved in the Ca(2+)-dependent phosphorylation of the enzyme.
Mol Cell Biochem 1993 Jul 21
PMID:Regulatory effect of regucalcin on (Ca(2+)-Mg2+)-ATPase in rat liver plasma membranes: comparison with the activation by Mn2+ and Co2+. 823 87

Previous studies have shown renal mesenchymal tumors (RMTs) induced in rats by a single intrarenal injection of nickel subsulfide and iron are more pleomorphic and metastatically aggressive than RMTs induced by a single ip injection of methyl(methoxymethyl)nitrosamine (DMN-OMe). While both RMT types contain high levels of K-ras activation, the specific mutational spectra within codon 12 of K-ras are quite different. Nickel subsulfide and iron-induced tumors exhibited codon 12 GGT-->GTT transversions exclusively, while DMN-OMe RMTs showed a wide array of codon 12 mutations, as well as mutations within codons 61 and 63 [K. G. Higinbotham, J. M. Rice, B. A. Diwan, K. S. Kasprzak, C. D. Reed, and A. O. Perantoni, Cancer Res., 52: 4747-4751, 1992; K. G. Higinbotham, J. M. Rice, and A. O. Perantoni, Mol. Carcinog., 5: 136-139, 1992]. In an effort to further correlate carcinogen-specific molecular events in renal tumors, we investigated the p53 tumor suppressor gene in RMTs induced by these two carcinogens for the presence of point mutations. The evolutionarily conserved portion of the coding region of the gene, including part of exon 4 through exon 10, was surveyed for point mutations utilizing single-strand conformation polymorphism and chemical cleavage of mismatches analyses. None (0 of 10) of the nickel subsulfide and iron-induced RMTs and only 1 of 10 DMN-OMe-induced tumors that were evaluated contained point mutations within this portion of the p53 gene. Direct sequencing of the one single-strand conformation polymorphism and chemical cleavage of mismatches-"positive" DMN-OMe-induced RMT revealed a GCC-->GTC (Ala-->Val) transition in codon 345 within exon 10. These results suggest that the different tumorigenic phenotypes exhibited by these two RMTs are not the result of specific mutations or patterns of mutations within the portion of the p53 gene examined and that the mutated p53 tumorigenic pathway, whereby p53 plays a major role in many human neoplasms, does not function in RMTs induced by either agent.
 ...
PMID:Low incidence of point mutations detected in the p53 tumor suppressor gene from chemically induced rat renal mesenchymal tumors. 826 41

mRNA from normal Chinese hamster embryo (CHE) cells was transcribed to cDNA and subtracted with an excess of mRNA from Chinese hamster embryo cells transformed by nickel compounds. Here we report the recovery of a sequence found to be highly homologous to the mouse thrombospondin 1 gene that was obtained by this subtraction procedure. Since thrombospondin is antiangiogenic, cancer cells expressing high levels of thrombospondin cannot grow in vivo because capillaries will not proliferate to cells secreting thrombospondin. To examine expression of thrombospondin, normal CHE cells were stained with monoclonal antibodies to human thrombospondin. The protein was present abundantly in the cytoplasm of normal cells but at greatly reduced levels in Ni-transformed cells. Analysis of mRNA by Northern (RNA) blot revealed transcripts in normal cells but little thrombospondin mRNA in Ni-transformed cells. Loss of thrombospondin mRNA expression was related to Ni treatment rather than transformation, since Ni-resistant cells also exhibited fewer thrombospondin transcripts than did wild-type cells. Digestion of genomic DNA with various combinations of restriction enzymes revealed thrombospondin gene patterns that were identical in both cell types, suggesting that there were no major deletions or rearrangements of the gene in the nickel-transformed cells. The inactivation of the thrombospondin gene was further investigated by analyzing the promoter activity of this gene linked to a chloramphenicol acetyltransferase (CAT) reporter plasmid that was transfected into normal and Ni-transformed cells. The CAT activity in normal cells was significantly higher than in Ni-transformed cells, suggesting that the promoter region of thrombospondin was less efficiently transcribed in Ni-transformed cells. We studied the consequences of enhanced expression of the retinoblastoma (Rb) gene, a known tumor suppressor gene, on CAT transcription driven by the human thrombospondin promoter. Cotransfection of an expression vector containing the mouse Rb gene greatly enhanced the transcription from the thrombospondin promoter such that the expression was higher in normal cells than in transformed cells.
Mol Cell Biol 1994 Jan
PMID:Loss of thrombospondin transcriptional activity in nickel-transformed cells. 826 52


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