Phenotypic switching in cells transformed with the herpes simplex virus thymidine kinase gene
Biochemical transformation of Ltk/sup -/ cells with the herpes simplex virus thymidine kinase (tk) gene resulted in numerous TK/sup +/ colonies that survived selection in hypoxanthine-aminopterin-thymidine medium. Many of these TK/sup +/ cell lines switched phenotypes and reverted to the TK/sup -/ state. In this report, the authors describe the biological and biochemical characteristics of three TK/sup -/ revertant lines. One (K/sub 1/B/sub 5/) transiently expressed TK in the presence of bromodeoxyuridine, which selects for the TK/sup -/ phenotype. Another TK/sup -/ sibling (K/sub 1/B/sub 6//sup n/) expressed TK only after removal from bromodeoxyuridine-containing medium. The last variant (K/sub 1/B/sub 6//sup me/) lost the ability to switch to the TK/sup +/ phenotype, although it maintained the herpes simplex virus sequences coding for TK. Loss of the ability of K/sub 1/B/sub 6//sup me/ cells to express TK was correlated with extensive methylation of the sequence recognized by the restriction endonuclease HpaII (pCpCpGpG). After these cells were treated with 5-azacytidine, they regained the ability to clone in hypoxanthine-aminopterin-thymidine medium and reexpressed virus tk mRNA and enzyme. In addition, the HpaII sites that were previously shown to be refractile to enzyme digestion were converted to a sensitive state, demonstrating that they were no longer methylated.
- Research Organization:
- Dept. of Microbiology and The Cancer Research Center, College of Physicians and Surgeons, Columbia Univ., New York, NY 10032
- OSTI ID:
- 5809822
- Journal Information:
- Mol. Cell. Biol.; (United States), Vol. 2:6
- Country of Publication:
- United States
- Language:
- English
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BUDR
TOXICITY
ENDONUCLEASES
ENZYME INHIBITORS
HERPES SIMPLEX
DNA SEQUENCING
PHOSPHOTRANSFERASES
BIOLOGICAL FUNCTIONS
GENES
REVERTANTS
BIOCHEMICAL REACTION KINETICS
CELL CULTURES
CELL TRANSFORMATIONS
COLONY FORMATION
CULTURE MEDIA
HYPOXANTHINE
MESSENGER-RNA
METHYLATION
MUTAGENESIS
PHENOTYPE
THYMIDINE
ANTIMETABOLITES
AROMATICS
AZAARENES
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BROMOURACILS
CHEMICAL REACTIONS
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DNA-ASE
DRUGS
ENZYMES
ESTERASES
FUNCTIONS
HETEROCYCLIC COMPOUNDS
HYDROLASES
HYDROXY COMPOUNDS
INFECTIOUS DISEASES
KINETICS
MUTANTS
NUCLEIC ACIDS
NUCLEOSIDES
NUCLEOTIDES
ORGANIC BROMINE COMPOUNDS
ORGANIC COMPOUNDS
ORGANIC HALOGEN COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
PHOSPHODIESTERASES
PHOSPHORUS-GROUP TRANSFERASES
PURINES
PYRIMIDINES
REACTION KINETICS
RIBOSIDES
RNA
SKIN DISEASES
STRUCTURAL CHEMICAL ANALYSIS
TRANSFERASES
URACILS
VIRAL DISEASES
550400* - Genetics
550700 - Microbiology