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

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Query: EC:2.7.1.21 (thymidine kinase)
7,561 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

We have studied the in vitro translation, in nuclease-treated reticulocyte lysates, of mRNA from cells infected with several thymidine kinase-deficient mutants of herpes simplex virus type I. The addition of suppressor tRNAs from yeast resulted in suppression of the mutant property in the case of two mutants. Synthesis of enzymatically active viral thymidine kinase was restored by serine-inserting amber suppressor tRNA in the case of HSV TK4- and synthesis of the intact, but inactive, thymidine kinase protein was restored by serine- and leucine-inserting UGA suppressor tRNAs in the case of HSV TK43-. Read-through of the normal termination at the end of the thymidine kinase gene was promoted by UGA suppressor tRNAs. We conclude that HSV-TK4- is an amber (UAG) mutant and that HSV-TK43- is an opal (UGA) mutant.
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PMID:In vitro suppression of UAG and UGA mutants in the thymidine kinase gene of herpes simplex virus. 21 1

Experiments were designed to identify herpes simplex virus type 2 (HSV-2)-specific functions expressed during stimulation of human embryo fibroblast DNA synthesis. Cultures were partially arrested in DNA synthesis by pretreatment with 5-fluorouracil and maintenance in low-serum (0.2%) medium during virus infection. Results showed that continuous [methyl-(3)H]thymidine uptake into cellular DNA was ninefold greater in HSV-2-infected than in mock-infected cultures measured after 24 h of incubation at 42 degrees C. Shifting mock-infected cultures from low- to high-serum (10%) medium also caused some stimulation, but [methyl-(3)H]thymidine uptake was only twofold greater than in cells maintained with low serum. Plating efficiencies of both HSV-2-infected and mock-infected cells at 42 degrees C were essentially the same and ranged from 37 to 76% between zero time and 72 h of incubation. De novo RNA and protein syntheses were continuously required for HSV-2 stimulation of cellular DNA synthesis. HSV-2 infection markedly enhanced transport, phosphorylation, and rate of incorporation of [methyl-(3)H]thymidine into cellular DNA, starting at 3 h and reaching a maximum by 12 h; after 12 h, these processes gradually declined to low levels. In mock-infected cells these processes remained at low levels throughout the observation period. Pretreatment of cells with interferon or addition of arabinofuranosylthymine at the time of virus infection inhibited stimulation caused by HSV-2. 5-Bromodeoxyuridine density-labeled experiments revealed that HSV-2 stimulates predominantly semiconservative DNA replication and some DNA repair. Stimulation of [methyl-(3)H]thymidine into cellular DNA correlated with detection of virus-specific thymidine kinase activity. In conclusion, HSV-2 stimulation of cellular DNA synthesis appeared to involve at least four virus-specific functions: induction of thymidine transport, HSV-2 thymidine kinase activity, semiconservative replication, and repair of cellular DNA.
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PMID:Herpes simplex virus type 2 functions expressed during stimulation of human cell DNA synthesis. 21 36

We have made use of a novel filter hybridization approach in order to map the herpes simplex virus (HSV) DNA sequences which are present in three HSV thymidine kinase (TK)-transformed cell lines. The cell line 33A+ which was produced by infection of 3T3 TK- cells with UV-irradiated HSV-2 (333) was found to contain one contiguous stretch of viral DNA sequences which maps between 0.15 and 0.57 on the HSV-2 genome. The sequences mapping from 0.31 to 0.37 were present in 3--4-fold higher abundance than the rest of the viral DNA sequences in this cell line. Cell lines 5A and 8N were produced by transfection of mouse CL1D cells with sheared HSV-1 (1023) DNA. The cell line 5A was found to contain a contiguous set of viral DNA sequences mapping between 0.26 and 0.41 on the HSV-1 genome. The cell line 8N was found to contain three non-contiguous sets of viral DNA sequences, mapping between 0.09 and 0.41, 0.53 and 0.58, and 0.94 and 1.0 on the HSV-1 genome. These results seem to indicate that many different sets of viral DNA sequences can be incorporated into the cell during HSV-mediated biochemical transformation.
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PMID:Mapping of the herpes simplex virus DNA sequences in three herpes simplex virus thymidine kinase-transformed cell lines. 22 51

The incidence of trigeminal ganglion infection after corneal inoculation of guinea pigs with thymidine kinase-negative mutants of herpes simplex virus was markedly reduced compared to infection after inoculation of thymidine kinase-positive virus. Thymidine kinase-negative herpes simplex virus replicated well in ocular tissues in which dividing or potentially dividing cells were present, but not in trigeminal ganglion infection of nondividing neurons. Thymidine kinase-positive virus, however, replicated well in ocular tissues as well as in trigeminal ganglion. These results suggest that thymidine kinase expression of herpes simplex virus may be important in infections of sensory ganglia.
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PMID:Trigeminal ganglion infection by thymidine kinase-negative mutants of herpes simplex virus. 22 54

The drug 9-(2-hydroxyethoxymethyl)guanine effectively inhibits herpes simplex virus replication. It is selectively phosphorylated by the virus-induced thymidine kinase but not by normal cellular thymidine kinase.
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PMID:9-(2-hydroxyethoxymethyl)guanine as an inhibitor of herpes simplex virus replication. 22 35

The phosphorylation of arabinofuranosylthymine (araThd) has been studied both in non-infected cells and in those infected with herpes simplex virus (HSV-1, Lennette; HSV-1, IES and HSV-2, D-316). In these experiments, HSV strains were used which either contain (Lennette, TK+ and D-316 TK+) or lack (IES, TK-) the capacity to induce pyrimidine deoxyribonucleoside kinase. It was found that extracellularly administered araThd is phosphorylated to ara TTP via araTMP and araTDP in both non-infected and in HSV-infected cells. The phosphorylating capacity is more than tenfold lower in non-infected cells than in infected cells. Interestingly, cells infected with the TK- strain have a tenfold higher phosphorylating capacity than normal, uninfected cells, a fact which might indicate that host cell deoxythymidine kinase is induced during HSV infection. AraTMP is incorporated into cellular DNA but not into HSV DNA. This finding is in contrast to observations with arabinofuranosyladenine, which is incorporated into both cellular and HSV DNA. In vitro experiments with HSV-induced DNA polymerase show that araTTP strongly inhibits the enzyme activity. Therefore we conclude that the inhibition of HSV DNA polymerase by araTTP (formed intracellularly from araThd) is the explanation for the observed antiviral activity of araThd.
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PMID:Phosphorylation of arabinofuranosylthymine in non-infected and herpesvirus (TK+ and TK-)-infected cells. 22 22

Pyrimidine deoxyribonucleoside kinase (thymidine kinase [TK]) was purified from two herpes simplex virus type 1 (HVS-1)-transformed TK-deficient mouse (LMTK-) cell lines and from LMTK- cells infected with HSV-1 mutant viruses coding for variant TK enzymes. These preparations exhibited normal or variant virus-induced thymidylate kinase activities correlating with their relative TK activities. Neither virus-induced activity was detected in LMTK- cells infected with an HSV-1 TK-deficient mutant. These results suggest that HSV-1 thymidylate kinase activity and TK activity are mediated by the same protein.
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PMID:Characterization of pyrimidine deoxyribonucleoside kinase (thymidine kinase) and thymidylate kinase as a multifunctional enzyme in cells transformed by herpes simplex virus type 1 and in cells infected with mutant strains of herpes simplex virus. 22 51

A technique for selecting herpes simplex viruses expressing the viral thymidine kinase (TK+) from a population of predominantly TK- viruses was developed. This was accomplished by infecting TK- cells and incubating the cultures under a liquid overlay medium containing methotrexate. Since the TK- cells survive in this medium for only a limited period of time, it was necessary to add fresh uninfected TK- cells 48 h after infection. The technique allowed the detection and quantitation of the TK+ virus fraction in mixtures of TK+ and TK- viruses where the TK+ fraction was present in frequencies as low as 10(-5). It was also used to estimate reversion frequencies and to obtain and analyze TK+ revertants from TK- mutant strains of herpes simplex virus type 1.
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PMID:Selective assay for herpes simplex viruses expressing thymidine kinase. 22 54

Thymidine kinase (TK)-deficient human cells were infected with ultraviolet light-inactivated Herpes simplex virus type 1, and "transformed" cells that expressed Herpes TK activity were isolated. Purified metaphase chromosomes were isolated from the transformed human line and incubated with TK-deficient mouse cells. TK+ cells were selected, and it was shown that these cells were gene transferents which expressed Herpes TK activity, identical to that found in the transformed human cells. The gene transferents contained no intact human chromosomes. When removed from selective pressure, the gene transferents rapidly lost the TK+ phenotype. However, upon continued growth in nonselective medium, a subpopulation in which the TK+ phenotype had become more stabilized appeared. These results suggest that the Herpes gene for thymidine kinase has integrated into the genome of the HSV-transformed human cells and that it can be transferred to other cells by means of purified metaphase chromosomes.
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PMID:Transfer of the herpes simplex thymidine kinase gene from human cells to mouse cells by means of metaphase chromosomes. 22 36

Herpes simplex virus type 1 (HSV-1) encoded thymidine kinase converts 5-iodo-5'-amino-2',5'-dideoxyuridine (AIdUrd), a highly specific anti-herpes agent, into the 5'-diphosphate (AIdUDP) derivative in vitro. AIdUDP was identified by its acid lability, sensitivity to alkaline phosphatase hydrolysis, chromatographic behavior, and ratio of double isotope (125I, 32P) labeling. ATP, but not AMP, is a phosphate donor, and the direct transfer of the beta and gamma phosphate of ATP as pyrophosphate to AIdUrd was ruled out. The presence of a phosphoramidate bond was supported by the acid lability of AIdUDP which has a half life (t1/2) of 320 min at pH 3.0. At neutral pH, the hydrolysis products are AIdUrd and orthophosphate, with AIdUrd monophosphate being the probable hydrolytic intermediate at these pH values. However, at acidic pH, some pyrophosphate was detected in addition to AIdUrd and orthophosphate. AIdUrd competitively inhibited the phosphorylation of thymidine and deoxycytidine. Escherichia coli thymidine kinase, even though 100-fold higher in activity, was unable to phosphorylate AId-Urd under similar incubation conditions.
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PMID:Phosphorylation of 5-iodo-5'-amino-2',5',dideoxyuridine by herpes simplex virus type 1 encoded thymidine kinase. 22 42


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