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

---

Query: EC:2.5.1.18 (glutathione S-transferase)
22,582 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The nucleotide sequence of the vaccinia virus open reading frame B1 predicts a polypeptide with significant sequence similarity to the catalytic domain of known protein kinases. To determine whether the B1R polypeptide is a protein kinase, we have expressed it in bacteria as a fusion with glutathione S-transferase. Affinity-purified preparations of the fusion protein were found to undergo autophosphorylation and also phosphorylated the exogenous substrates casein and histone H1. Mutation of lysine 41 to glutamine within the conserved kinase catalytic domain II abrogated protein kinase activity on all three protein substrates, supporting the notion that the protein kinase activity is inherent to the B1R polypeptide. Casein and histone H1 were phosphorylated on serine and threonine residues. The B1R fusion protein was phosphorylated on a threonine residue(s) by an apparently intramolecular mechanism. The autophosphorylation reaction resulted in phosphorylation of the glutathione S-transferase portion of the fusion and not the protein kinase domain. The protein kinase activity of B1R was specific for ATP as the phosphate donor; GTP was not utilized to a detectable extent. Immunoblotting experiments with anti-B1R antiserum showed that the protein kinase is located in the virion particle. Chromatography of virion extracts resulted in separation of the B1R protein kinase from the bulk of the total protein kinase activity, indicating that multiple protein kinases are present in the virion particle and that B1R is distinct from the previously described vaccinia virus-associated protein kinase.
...
PMID:The vaccinia virus B1R gene product is a serine/threonine protein kinase. 156 May 22

Sequence analysis of the genomes of the Leporipoxviruses myxoma virus and Shope fibroma virus (SFV) led to the discovery of open reading frames homologous to the vaccinia H1L gene encoding a soluble protein phosphatase with dual tyrosine/serine specificity. These viral phosphatase genes were subsequently localized to the myxoma BamHI-I fragment and the SFV BamHI-M fragment, and the resulting encoded proteins were designated I1L and M1L, respectively. The localization and orientation of the myxoma I1L and SFV M1L open reading frames within the well conserved central core of the viral genomes closely mirror that of the Orthopoxviruses vaccinia virus and variola virus. The myxoma I1L and SFV M1L phosphatases each contain the conserved tyrosine phosphatase signature sequence motif, (I/V)HCXAGXXR(S/T)G, including the active site cysteine, found previously to be essential for phosphotyrosine dephosphorylation. The vaccinia H1L phosphatase was originally shown to have the ability to dephosphorylate phosphotyrosyl and phosphoseryl residues in vitro. To assess whether this is a common feature of poxvirus phosphatases, myxoma I1L was expressed as a GST-fusion protein, purified, and shown to dephosphorylate substrates containing tyrosine and serine phosphorylated residues, in a similar fashion to vaccinia H1L. A myxoma I1L variant, in which the active site cysteine 110 was mutated to serine, was expressed in a parallel fashion to the wild-type I1L protein and found to be completely deficient in its ability to dephosphorylate both phosphotyrosine and phosphoserine amino acids. In an attempt to ascertain the biological requirement for the myxoma I1L phosphatase, we constructed a recombinant myxoma virus containing a disrupted I1L open reading frame. This I1L mutant virus was able to successfully propagate in tissue culture only in the presence of a wild-type complementing gene, and pure virus clones containing only the disrupted allele were not viable. Thus, we conclude that the myxoma I1L dual specificity phosphatase is an essential factor for virus viability.
...
PMID:Myxoma virus and Shope fibroma virus encode dual-specificity tyrosine/serine phosphatases which are essential for virus viability. 783 13

The vaccinia virus-encoded protein VP39 is a poly(A) polymerase subunit that stimulates the formation of long poly(A) tails as well as a cap-specific mRNA (nucleoside-2'-O-)-methyltransferase. We have carried out mutagenesis studies aimed at locating regions of VP39 which are important for these activities. The open reading frame encoding VP39 was expressed in Escherichia coli as a glutathione S-transferase fusion protein. The affinity-purified protein had both mRNA modification activities, before and after removal of the glutathione S-transferase domain. Truncation, charge cluster-->Ala scanning, and Cys-->Ser substitution mutations of VP39 were made, and the proteins were synthesized, purified, and analyzed. Deletion of the RNA binding domain, experimentally localized within the carboxyl-terminal 112 amino acids, resulted in the loss of both mRNA modification activities. Eleven of the 21 charge cluster-->Ala mutated proteins had low to nondetectable methyltransferase activity. Four of those 11 also lacked adenylyl-transferase stimulatory function, whereas the remainder had amino acid substitutions that selectively affected methyltransferase activity. However, no mutated proteins lacking adenylyltransferase stimulatory function but possessing methyltransferase activity were isolated by the procedures used. Neither of the 2 cysteine residues in VP39 was necessary for either mRNA modification activity.
...
PMID:Mutational analysis of a multifunctional protein, with mRNA 5' cap-specific (nucleoside-2'-O-)-methyltransferase and 3'-adenylyltransferase stimulatory activities, encoded by vaccinia virus. 805 Nov 70

The major protein kinase activity from vaccinia virus core particles was purified to near homogeneity. The protein kinase is a 50-kDa polypeptide that is shown here to phosphorylate primarily seryl residues in alpha-casein, a casein kinase I-specific peptide substrate, and itself through autophosphorylation. The sequence of four peptides derived from the protein kinase demonstrated that it is encoded by the vaccinia virus F10L gene. Expression of the F10L gene product in bacteria as a fusion with glutathione S-transferase confirmed that the vaccinia F10L gene encodes the protein kinase. We have termed this enzyme vaccinia protein kinase 2 (VPK2) to distinguish it from the protein kinase encoded by the vaccinia B1R gene. Targeted disruption of the VPK2 gene with a positive selectable marker demonstrated that all viruses with a disrupted gene also possessed a wild-type gene, suggesting that VPK2 is essential for viability. The discovery of a second essential protein kinase encoded by vaccinia virus, in addition to a protein phosphatase, underscores the importance of protein phosphorylation in poxvirus biogenesis.
...
PMID:Vaccinia protein kinase 2: a second essential serine/threonine protein kinase encoded by vaccinia virus. 805 37

We have characterized a growth factor-inducible gene, erp, and demonstrated that it encodes a 367-amino-acid nontransmembrane tyrosine phosphatase protein with significant similarity to the vaccinia virus H1 protein. Immunoprecipitation analyses show that the erp protein, ERP, is rapidly induced following serum stimulation of quiescent fibroblasts. ERP has been expressed as a fusion protein with glutathione S-transferase and shown to have tyrosine as well as serine protein phosphatase activity. The enzymatic activity of ERP depends on the presence of reducing agents such as dithiothreitol, and its tyrosine phosphatase activity is inhibited by sodium vanadate, a potent inhibitor of protein tyrosine phosphatases. The number of stable NIH 3T3 clones obtained after transfection with a vector expressing the complete ERP protein is reduced more than 90% compared with that after transfection with a vector expressing a mutated inactive ERP protein. The remaining ERP-expressing clones present a significant increase in the proportion of bi- and multinucleated cells and a decrease in proliferation rate. Studies on the genomic structure reveal that the erp transcription unit is 2.8 kbp long and split into four exons. The erp gene maps to the 17A2-17C region of the murine genome. Our results demonstrate that the protein product of the immediate-early gene erp has a negative effect on cell proliferation.
...
PMID:Structure, mapping, and expression of erp, a growth factor-inducible gene encoding a nontransmembrane protein tyrosine phosphatase, and effect of ERP on cell growth. 835 78

The sequence of the vaccinia virus open reading frame F2L predicts a polypeptide with significant similarity to cellular dUTPases. To determine whether the F2L gene product has this activity, it was expressed in bacteria as a fusion with glutathione S-transferase. Affinity purified fusion protein was shown to hydrolyze dUTP yielding dUMP as the product. While the dUTPase was not completely dependent on the addition of divalent cations, its activity was stimulated markedly by Zn2+, Mg2+, and Mn2+. The nucleotide substrate specificity of the enzyme was limited to dUTP. These results demonstrate that vaccinia virus encodes a functional dUTPase whose role in viral infection is suggested to be the augmentation of DNA nucleotide precursors and the minimization of cytoplasmic dUTP concentrations.
...
PMID:Vaccinia virus encodes a functional dUTPase. 839 52

The African swine fever virus (ASFV) open reading frame (ORF) that is named jl8L in the Malawi (LIL20/1) isolate and E199L in the Ba71V isolate encodes a cysteine rich protein of 195 amino acids with a predicted molecular mass of 21.7 kDa and a hydrophobic domain near the C terminus. There are several possible motifs for glycosylation, phosphorylation and myristoylation. Rabbit antisera and monoclonal antibodies raised against a recombinant ASFV j18L protein expressed as a fusion protein with glutathione S-transferase (GST) identified proteins of 19.0-20 kDa in cells infected with different ASFV strains and with a recombinant vaccinia virus expressing j18L. The monoclonal antibodies detected a protein of 20.0 kDa whereas rabbit antisera detected two proteins with relative molecular masses of 15.0 and 20.0 kDa in purified extracellular ASF virions. In ASFV-infected cells, the j18L protein was expressed late post-infection and was localized mainly in the viral factories.
...
PMID:Characterization of the African swine fever virion protein j18L. 860 90

Poxviral DNA topoisomerases are sequence-specific enzymes whose activities are thought to influence such diverse processes as transcription, DNA replication, and genetic recombination. To obtain further insights into the relatedness of these enzymes, and their influence on virus-mediated recombination, we have determined the target-specificity and other catalytic properties of the Shope fibroma virus (SFV) topoisomerase. SFV topoisomerase was expressed in Escherichia coli and purified as a glutathione S-transferase (GST) or (his)6-tagged fusion protein. The recombinant Leporipox-virus (SFV) enzyme displayed catalytic properties very similar to vaccinia topoisomerase. In particular SFV topoisomerase recognizes the same pentanucleotide motif [5'-(C/T)CCTT-3'] and promotes the same DNA relaxation, strand transfer, and strand cleavage reactions catalyzed by the Orthopoxviral (vaccinia) enzyme. The SFV enzyme can also efficiently cleave DNA 3' of the variant site 5'-CCCTG-3' in certain sequence contexts. These studies identified several sites where SFV topoisomerases interact with a recombinational substrate and permitted a comparison of recombination frequencies across intervals which did, or did not, span these sites. We failed to detect any effect of topoisomerase-recognition sites on recombination frequencies, except for a small (< 2-fold) stimulation seen when the substrates encoded a nearby poxviral promoter. This and other work shows that poxviral topoisomerases from several genera share common target specificities, but other enzymatic systems probably catalyze the high-frequency recombination seen in poxvirus-infected cells.
...
PMID:SFV topoisomerase: sequence specificity in a genetically mapped interval. 866 46

Flaviviruses generate their structural and nonstructural proteins by proteolytic processing of a single large polyprotein precursor. These proteolytic events are brought about both by host cell signalase and a virally encoded protease. The virally encoded proteolytic activity has been shown to reside within the nonstructural protein 3 (NS3) and requires the product of the nonstructural 2b (NS2b) gene. In order to obtain sufficient quantities of pure NS2b and NS3 proteins for kinetic analysis, we have expressed both these proteins in recombinant systems as fusions to glutathione S-transferase (GST). The fusion constructs were driven by the strong bacteriophage T7 promoter. Transfection of these constructs into the African green monkey kidney cell line CV-1 previously infected with a recombinant vaccinia virus expressing the T7 RNA polymerase resulted in synthesis of the fusion proteins. Both the fusion proteins could be purified to homogeneity in a single step using a glutathione agarose affinity matrix.
...
PMID:Expression of the Japanese encephalitis virus NS3 and NS2b proteins as glutathione S-transferase fusions. 871 4

VP39 is a bifunctional vaccinia virus protein that acts as both a cap- dependent 2'-O-Methyltransferase and a poly(A) polymerase processivity factor. An analysis of C-terminal truncation mutants of a GST-VP39 fusion protein indicated the presence of a protease-sensitive C-terminal "tail" 36-43 amino acids in length that is non-essential for VP39 function. Fourteen new VP39 pointmutants, containing either single or multiple-clustered amino acid substitutions, were expressed in Escherichia coli. Of the eight that retained either one or both of the activities of VP39, seven were specifically methyltransferase-defective. None was specifically defective in adenylyltransferase stimulation. The nature of the methyltransferase defects in 10 of the methyltransferase-specific defectives, identified both herein and in a previous study (Schnierle BS, Gershon PD, Moss B, 1994, J biol Chem 269:20700-20706), was investigated using two novel substrate-binding assays. Three of the mutants (and possible a fourth), whose lesions were juxtaposed and centrally located within VP39, exhibited anomalous S-adenosyl-(L)-methionine (AdoMet) binding behavior, identifying residues important for AdoMet binding and possible also for catalysis. A surface plasmon resonance-based assay measured the interaction of VP39 with uncapped and 5'-cap 0-terminated oligo(A). A cap 0- dependent association-rate enhancement was observed for wild-type VP39 and 4 of the 10 mutant proteins. Two others were identified as defective in cap binding, and a third as partially defective. The lesions within the latter three mutants were closely apposed, and located toward the N-terminus of VP39. We have thus identified regions of VP39 important for interaction with its two substrates for cap-dependent methyltransferase activity: AdoMet and cap 0.
...
PMID:Methyltransferase-specific domains within VP-39, a bifunctional protein that participates in the modification of both mRNA ends. 884


1 2 3 4 Next >>

---