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 characterized a chloroplast processing activity that catalyzes the conversion of the plastid cytochrome b6/f subunit IV (pet D) mRNA 3' end precursor to the mature RNA possessing a 3' inverted repeat (IR). In a chloroplast soluble protein extract, the activity requires Mg2+ or Mn2+, but not K+. In the absence of Mg2+, the pet D 3' IR-RNA product does not accumulate, and UV-cross-linking indicates that the 3' IR-RNA precursor binds several new proteins in addition to those previously characterized as part of the 3' IR-RNA: protein complex in vitro. In contrast, high concentrations of Zn2+ or Cu2+ suppress protein binding and inhibit the processing reaction. The purified exoribonuclease polynucleotide phosphorylase (E.C.2.7.7.8) is not efficient in processing the pet D 3' IR-RNA precursor, whereas Escherichia coli ribonuclease II rapidly processes the pet D IR-RNA precursor to a product of a size similar to that of the mature 3' IR-RNA, but also rapidly degrades the mature RNA in the absence of chloroplast extract. We therefore conclude that the maturation of the pet D mRNA in vitro requires specific chloroplast enzymes which process the mRNA 3' end precursor in the absence of efficient transcription termination. The chloroplast enzyme activities are biochemically distinct from their bacterial counterparts. We also note that specific chloroplast components may be required to stabilize the mature pet D mRNA 3' end against further exonucleolytic degradation.
Plant Mol Biol 1989 Dec
PMID:Chloroplast mRNA 3' end maturation is biochemically distinct from prokaryotic mRNA processing. 248 89

The gene encoding plastocyanin (petE1) from Anabaena sp. PCC 7937 was isolated using two sets of mixed oligonucleotide hybridization probes derived from conserved regions in the protein. Plastocyanin is encoded as a preprotein of 139 amino acids. The amino-terminal extension of 34 residues has all the characteristics of a signal peptide and is probably involved in translocation of preplastocyanin over the thylakoid membrane. The level of the petE1 mRNA, a single transcript of about 740 bases, was found to be severely reduced under conditions of Cu2+ deficiency. The petE1 gene was transferred to the genome of Synechococcus sp. PCC 7942, which did not appear to contain a structural gene for plastocyanin itself. The integrated gene becomes expressed at the transcriptional level, regardless of the amount of Cu2+ available.
Mol Microbiol 1989 Mar
PMID:The gene for the precursor of plastocyanin from the cyanobacterium Anabaena sp. PCC 7937: isolation, sequence and regulation. 250 29

Prostaglandin E2 (PGE2) is known to stimulate the release of luteinizing hormone releasing hormone (LHRH) from explants of the median eminence area (MEA). We have previously shown that a short preincubation of the MEA with copper markedly amplifies PGE2 stimulation of LHRH release and that the Ca2+-cAMP pathway is involved in this release process. In this study, we defined the kinetics of the onset of PGE2 action and examined the Ca2+ requirement for the onset and manifestation of PGE2 action. MEA explants from immature female rats were incubated with copper (150 microM copper-histidine complex); thereafter, explants were exposed to 10 microM PGE2 for periods of 2-7 min with or without Ca2+ (Ca2+-free buffer containing 1 mM EGTA). A 2 min PGE2 exposure was as effective as a 7 min PGE2 exposure in stimulating LHRH release; the latter was manifested during the period between 2-7 min. When MEA were exposed to PGE2 for 5 min, maximal rate of release was attained within this 5 min period. When MEA were exposed to PGE2 for 2 min and then to forskolin (100 microM) for 5 min, there was no further increase in the rate of LHRH release (although exposure to forskolin alone maximally stimulated LHRH release). In the presence of EGTA (no Ca2+), PGE2 stimulation of LHRH release was abolished and this effect of EGTA was totally reversed by the addition of Ca2+ 2 min after PGE2 exposure and partially reversed (40%) by the addition of Ca2+ 5 min after PGE2 exposure in the presence of EGTA.(ABSTRACT TRUNCATED AT 250 WORDS)
Mol Cell Endocrinol 1989 Aug
PMID:A rapid, Ca2+-independent, onset of prostaglandin E2 stimulation of the release of luteinizing hormone releasing hormone from copper-treated median eminence explants. 250 87

The simian virus 40 (SV40) enhancer consists of multiple DNA sequence motifs that represent the binding sites for a large number of trans-acting factors. We have purified one such factor, EBP1, which binds to a region encompassing the "core" of the SV40 enhancer, and appears to be involved in transcriptional activation. The interaction of EBP1 with its recognition site has been analysed by nuclease protection and by a variety of chemical probes. Enhancer sequences protected from cleavage with DNase I in the presence of EBP1 extend from position 232 to 250 on one strand and from 233 to 251 on the other strand. Methylation protection and alkylation interference studies have identified purine bases and backbone phosphate groups that participate in the formation of a specific EBP1-DNA complex. Within a ten base-pair region, every purine base interferes with binding when methylated and six phosphate groups on each strand interfere with binding when the attached oxygen groups are ethylated. "Footprinting" with hydroxyl radicals, generated by the 1,10-orthophenanthroline-copper ion, revealed sugar residues in the binding site that were protected from cleavage in the presence of EBP1. Computer graphics analyses of the contact point data indicate that EBP1 makes base and backbone contacts with the DNA over one complete turn of the DNA double helix, and suggest a model in which EBP1 makes sequence-specific contacts in the major groove, although binding may be influenced by interactions in the minor groove. Comparison of the EBP1 contact points with that of other known DNA-binding proteins indicates that EBP1 employs a unique mechanism to recognize a specific DNA sequence.
J Mol Biol 1989 Apr 20
PMID:Enhancer binding protein (EBP1) makes base and backbone contacts over one complete turn of the DNA double helix. 254 31

During the initial 4 h of treatment, copper and zinc similarly activated the rates of transcription and mRNA accumulation from the two human metallothionein (MT) genes, viz., MTI-G and MTII-A, in the hepatoblastoma cell line HepG2. The levels of copper-induced MT mRNAs remained at a plateau for up to 15 h. In contrast, the levels of zinc-induced MT mRNAs gradually declined after about 4 h, despite substantial transcription. The decrease in the zinc-induced MT mRNA half-life is probably due to a posttranscriptional event(s).
Mol Cell Biol 1989 Dec
PMID:Metal-specific posttranscriptional control of human metallothionein genes. 255 5

The use of non-crystallographic symmetry restraints in the refinement of the haemocyanin hexamer from Panulirus interruptus at 3.2 A resolution has resulted in a final model with a very reasonable geometry and a crystallographic R-factor of 20.1%, using 59,193 observed structure factor amplitudes between 8.0 and 3.2 A. The mean co-ordinate error is approximately 0.35 A. The six subunits appear to be related by symmetry operations that differ slightly from 32 point group symmetry. The six subunits have essentially maintained the same structure. The hexamer, with point group 32, is best described as a trimer of "tight dimers". The contacts between the subunits in such a dimer are more numerous, and better conserved during evolution than contacts in a trimer. The interface of a tight dimer is separated by an internal cavity into two "contact areas". The contact area nearest to the centre of the hexamer is most extensive and consists mainly of residues that are quite conserved among arthropodan haemocyanins. All these residues are provided by the second domain of each subunit. Hence, this second domain may play a crucial role in the allosteric functioning of this oxygen transport protein. The dinuclear copper oxygen-binding site resides in the centre of domain 2. This oxygen-binding centre is not fully accessible from the solvent. Three large cavities occur, however, within each subunit at the interfaces of the three domains. All three cavities contain ordered water molecules, and two of them are accessible from the surrounding solvent. These cavities may play a role in facilitating fast movement of dioxygen towards the binding site, which is situated in a highly conserved, rather hydrophobic core. A detailed definition of the geometry of the copper site is, of course, not possible at the limited resolution of 3.2 A. Nevertheless, it is possible to conclude that each copper is co-ordinated by two, more or less tightly bound, histidine ligands and one more distant histidine residue. The six histidine residues utilize their N epsilon atoms for copper co-ordination, while their N delta atoms are engaged in hydrogen bonds with conserved residues or water molecules. The two distant histidine ligands are located in apical positions and are on opposite sides with respect to the plane approximately defined by the four more tightly bound histidine ligands and the two copper ions. The copper-to-copper distance is 3.5 to 3.6 A in four of the subunits, but this distance deviates considerably in two others.(ABSTRACT TRUNCATED AT 400 WORDS)
J Mol Biol 1989 Sep 20
PMID:Crystal structure of hexameric haemocyanin from Panulirus interruptus refined at 3.2 A resolution. 258 84

The interaction of DNA with divalent metal ions: Ba2+, Mg2+, Mn2+, Ni2+, Cu2+ in solutions at different ionic strengths mu was investigated. The combination of following methods: flow birefringence, viscometry, UV-spectroscopy and circular dichroism made possible to follow the state of the secondary and tertiary structure of the DNA molecule during its interaction with ions. The presence of divalent ions in solution affects the hydrodynamic properties of DNA only at low mu. At high mu the difference in the action of mono- and divalent ions disappears. The persistence length of DNA does not change during the experiment. It is shown that the Mg2+ and Ba2+ ions interact only with phosphate groups of DNA but Mn2+, Ni2+, Cu2+ ions interact also with the nitrogen bases of the macromolecule.
Mol Biol (Mosk)
PMID:[A study of the molecular mechanism of DNA interaction with divalent metal ions]. 258 10

Rabbit histidine-rich glycoprotein (HRG) binds low-spin heme and metals tightly at several sites that contain histidine. As part of an on-going effort to define and locate the binding sites for these and the other ligands of HRG, the sequence: NH2-Gly-His-Phe-Pro-Phe-His-Trp-... was found in a 16 kDa heme-binding peptide isolated from HRG. The spacing of the histidyl residues in this peptide, which contains the C-terminal 79 residues of HRG, together with molecular modeling suggested that this sequence might constitute one heme binding site of HRG by accommodating heme in a bis-histidyl linkage. Three peptides based on this sequence (I, HFPFHW; II, WHFPFH; and III, HFGFHW) were synthesized, and their ability to bind heme and metals examined. All three peptides bind heme as demonstrated by the changes produced in the absorbance of heme when mixed with the peptides. Substituting glycine for proline in the central position or moving the location of the tryptophan did not affect heme binding. The apparent Kd's of the mesoheme/peptide I, II and III complexes are 75 +/- 25 microM, indicative of heme binding approximately 100 times less avid than the mesoheme/HRG complex (Kd ca. 1 microM), but nearly 1000 times tighter than that of the mesoheme/histidine complex (Kd ca. 60 mM). The absorbance spectra of the mesoheme/peptide complexes, the loss of binding caused by modification of histidine residues, and the pH dependence of heme binding, all indicate that heme forms a low spin, bis-histidyl type of complex with these peptides, like that formed with HRG itself. Copper, but not cadmium or nickel, was an effective inhibitor of heme binding by the peptides. The sequence of HRG congruent with the sequence of peptide I is proposed to be one heme- and metal-binding site of rabbit HRG.
J Mol Recognit 1989 Nov
PMID:A heme- and metal-binding hexapeptide from the sequence of rabbit plasma histidine-rich glycoprotein. 263 1

The ACE1 gene of the yeast Saccharomyces cerevisiae is required for copper-inducible transcription of the metallothionein gene (CUP1). The sequence of the cloned ACE1 gene predicted an open reading frame for translation of a 225-amino-acid polypeptide. This polypeptide was characterized by an amino-terminal half rich in cysteine residues and positively charged amino acids. The arrangement of many of the 12 cysteines in the configuration Cys-X-Cys or Cys-X-X-Cys suggested that the ACE1 protein may bind metal ions. The carboxyl-terminal half of the ACE1 protein was devoid of cysteines but was highly acidic in nature. The ability of a bifunctional ACE1-beta-galactosidase fusion protein to accumulate in yeast cell nuclei was consistent with the possibility that ACE1 plays a direct role in the regulation of copper-inducible transcription of the yeast metallothionein gene.
Mol Cell Biol 1989 Feb
PMID:A cysteine-rich nuclear protein activates yeast metallothionein gene transcription. 265 99

FNR, the transcriptional regulator of gene expression of anaerobic respiration in Escherichia coli, contains a cluster of cysteine residues at the amino terminus which resembles the metal-binding domains of metal-binding proteins. It is possible, therefore, (i) that FNR binds metals with the cysteines as ligands and (ii) that this property is related to the regulatory function of FNR. These questions were investigated, with the following results. Approximately 2.4 of the 4 cysteine residues of FNR can be alkylated with iodoacetate in permeabilized aerobic or anaerobic bacteria without the addition of reducing agents. The time required for half-maximal labelling of the cysteines was 50 min in anaerobic bacteria and 6 min in aerobic bacteria. The difference in the reactivity was specific for the cysteines of FNR. These cysteine residues were also highly reactive in anaerobically grown bacteria, when the growth medium contained chelating agents such as 1,10-phenanthroline (15 microM). The effect of the chelating agents was reversed by an excess of divalent metal ions such as Fe(II) or Cu(II) in the medium. The presence of 1,10-phenanthroline (10 microM) also inhibits the expression of fumarate reductase, an FNR-dependent enzyme. These results suggest that FNR exists in two different forms which differ in terms of the reactivity of their cysteine residues to iodoacetate. The interconversion of both forms appears to be regulated by the availability of O2 and by the binding of metal ions. The two forms of FNR may be involved in the regulation of O2-dependent gene expression.
Mol Microbiol 1989 May
PMID:Role of cysteine residues and of metal ions in the regulatory functioning of FNR, the transcriptional regulator of anaerobic respiration in Escherichia coli. 266 93


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