Deoxyribonucleic Acid Polymerase Associated with Rous Sarcoma Virus and Avian Myeloblastosis Virus: Properties of the Enzyme and Its Product
TL;DR: The results of both zonal and equilibrium centrifugation indicate that nascent chains of DNA are associated with the 70S viral RNA, and it is concluded that at least two enzymatic activities are under study: transcription of DNA from viral RNA and subsequent, additional synthesis of DNA.
Abstract: Deoxyribonucleic acid (DNA) polymerase activity can be elicited in purified preparations of avian myeloblastosis virus and Rous sarcoma virus (Schmidt-Ruppin strain) by treatment with nonionic detergent. The enzyme(s) and its synthetic products appear to be virion-associated. Enzymatic activity can be inhibited by pretreatment with either ribonuclease (8- to 10-fold inhibition) or actinomycin D (twofold inhibition). By contrast, rifampin has little, if any effect. The enzyme(s) synthesizes two primary products, a ribonucleic acid (RNA):DNA hybrid and DNA which is free of RNA. The results of both zonal and equilibrium centrifugation indicate that nascent chains of DNA are associated with the 70S viral RNA. It is concluded that at least two enzymatic activities are under study: transcription of DNA from viral RNA, and subsequent, additional synthesis of DNA, utilizing product of the initial reaction as template.
Citations
More filters
TL;DR: The DNAase digestion end-product of calf thymus DNA contains oligonucleotides that will function as primers for the efficient transcription into DNA of many naturally-occurring RNA's by purified avian sarcoma virus RNA-directed DNA polymerase.
643 citations
TL;DR: It is hypothesized that the leukovirus RNA-directed DNA polymerase activity is an integral part of the ribonucleoprotein core of the virions, which suggests that the virion enzyme activity is related to normal cellular DNA polymerases, and that there are homologies between the amino acid sequences of the viral enzyme and normal cellular enzymes.
Abstract: Publisher Summary The discovery of RNA-directed DNA synthesis in disrupted virions of RNA tumor viruses added strong support to the hypothesis that information transfer from RNA to DNA exists in biological system. The chapter discusses the properties of the endogenous reaction carried out by the virion DNA polymerase. To study the endogenous reaction disrupted, virions are incubated with substrates in the absence of any added template and synthesis of DNA is observed using the RNA present in the virions as template. The chapter also discusses the general implications of RNA-directed DNA synthesis in relation to tumor viruses, neoplastic cells, and normal cells. It is hypothesized that the leukovirus RNA-directed DNA polymerase activity is an integral part of the ribonucleoprotein core of the virions. The cores are synthesized in cells as precursor particles and then are incorporated into complete virions when the virions are assembled by budding at the cell surface. This core enzyme system contains not only the template-primer RNA, a DNA polymerase that can transfer information from RNA to double-stranded DNA, but ancillary enzymes, such as polynucleotide ligase and nucleases, which may aid in integrating the viral information with cellular DNA. This suggests that the virion enzyme activity is related to normal cellular DNA polymerases, and that there are homologies between the amino acid sequences of the viral enzyme and normal cellular enzymes. The relationship of RNA-directed DNA synthesis to neoplasia depends upon the relationship of RNA tumor viruses to neoplasia, which is supported by three general hypotheses: the provirus model, the oncogene model, and the protovirus model.
400 citations
TL;DR: DNA polymerase from avian myeloblastosis virus has been purified by a combination of column chromatography and gel filtration methods and possesses the RNA-, DNA-, and hybrid-directed polymerase activities found in the virion.
276 citations
TL;DR: Cells producing Rous sarcoma virus contain virus-specific ribonucleic acid (RNA) which can be identified by hybridization to single-stranded deoxyribonucleics acid (DNA) synthesized with RNA-directed DNA polymerase, and the hybrids formed have a high order of thermal stability.
Abstract: Cells producing Rous sarcoma virus contain virus-specific ribonucleic acid (RNA) which can be identified by hybridization to single-stranded deoxyribonucleic acid (DNA) synthesized with RNA-directed DNA polymerase. Hybridization was detected by either fractionation on hydroxyapatite or hydrolysis with single strand-specific nucleases. Similar results were obtained with both procedures. The hybrids formed between enzymatically synthesized DNA and viral RNA have a high order of thermal stability, with only minor evidence of mismatched nucleotide sequences. Virus-specific RNA is present in both nuclei and cytoplasm of infected cells. This RNA is remarkably heterogeneous in size, including molecules which are probably restricted to the nucleus and which sediment in their native state more rapidly than the viral genome. The nature of the RNA found in cytoplasmic fractions varies from preparation to preparation, but heterogeneous RNA (ca. 4-50S), smaller than the viral genome, is always present in substantial amounts.
267 citations
TL;DR: In this article, the authors investigated the mechanisms by which dexamethasone (a synthetic glucocorticoid) stimulates the production of mouse mammary tumor virus (MMTV) by cell cultures derived from mammary carcinomas of GR mice.
252 citations
References
More filters
Journal Article•
TL;DR: Procedures are described for measuring protein in solution or after precipitation with acids or other agents, and for the determination of as little as 0.2 gamma of protein.
289,852 citations
TL;DR: Two independent groups of investigators have found evidence of an enzyme in virions of RNA tumour viruses which synthesizes DNA from an RNA template, apparently the classical process of information transfer from DNA to RNA can be inverted.
Abstract: Two independent groups of investigators have found evidence of an enzyme in virions of RNA tumour viruses which synthesizes DNA from an RNA template. This discovery, if upheld, will have important implications not only for carcinogenesis by RNA viruses but also for the general understanding of genetic transcription: apparently the classical process of information transfer from DNA to RNA can be inverted.
1,872 citations
"Deoxyribonucleic Acid Polymerase As..." refers background in this paper
...It has been reported previously that the native, early product of the enzyme reaction is relatively shielded from degradative enzymes unless first diluted into low concentrations of electrolytes (3)....
[...]
...Substantial support for this hypothesis has been provided by the discovery of a novel DNA polymerase which is associated with the virions of RNA tumor viruses, and which apparently transcribes DNA from an RNA template (3, 14)....
[...]
...The hypothesis that the DNA product serves as an intermediate in viral RNA replication and that it is integrated into host DNA to provide for stable transformation (3, 13, 14) is logically persuasive VOL....
[...]
TL;DR: Viral RNA-dependent DNA Polymerase: RNA- dependent DNA polymerase in Virions of Rous Sarcoma Virus and its role in cell reprograming is studied.
Abstract: Viral RNA-dependent DNA Polymerase: RNA-dependent DNA Polymerase in Virions of Rous Sarcoma Virus
1,833 citations
590 citations
"Deoxyribonucleic Acid Polymerase As..." refers background in this paper
...Substantial support for this hypothesis has been provided by the discovery of a novel DNA polymerase which is associated with the virions of RNA tumor viruses, and which apparently transcribes DNA from an RNA template (3, 14)....
[...]
...The hypothesis that the DNA product serves as an intermediate in viral RNA replication and that it is integrated into host DNA to provide for stable transformation (3, 13, 14) is logically persuasive VOL....
[...]
TL;DR: Several RNA tumour viruses contain an enzyme that synthesizes a DNA–RNA hybrid using the single stranded viral RNA as template, and hybridization experiments confirm that the DNA strand is complementary to the viral RNA.
Abstract: Several RNA tumour viruses contain an enzyme that synthesizes a DNA–RNA hybrid using the single stranded viral RNA as template. Hybridization experiments confirm that the DNA strand is complementary to the viral RNA.
261 citations
"Deoxyribonucleic Acid Polymerase As..." refers methods in this paper
...Results of experiments utilizing denaturation with formamide (11) and dimethyl sulfoxide (in preparation) substantiate this conception....
[...]