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Vogt VM, Eisenman R, Diggelmann H. Generation of avian myeloblastosis virus structural proteins by proteolytic cleavage of a precursor polypeptide. J Mol Biol 1975; 96:471-93. [PMID: 170408 DOI: 10.1016/0022-2836(75)90174-6] [Citation(s) in RCA: 252] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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Abrams HD, Rohrschneider LR, Eisenman RN. Nuclear location of the putative transforming protein of avian myelocytomatosis virus. Cell 1982; 29:427-39. [PMID: 6288259 DOI: 10.1016/0092-8674(82)90159-3] [Citation(s) in RCA: 206] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
The putative transforming protein of avian myelocytomatosis virus MC29 is a 110,000 dalton (P110gag-myc) polyprotein comprised of sequences derived from both the gag region and the MC29-specific myc region. Two approaches have been taken to determine the location of the MC29 gag-related proteins in transformed cells: subcellular fractionation and immunofluorescence. Analysis of subcellular fractions of MC29-transformed cells by immunoprecipitation indicates that the majority of the gag-myc polyprotein is found in the nuclear fractions of Q8 cells (a nonproducer line of MC29-transformed quail embryo fibroblasts) and nonproducer cells derived from a liver tumor of MC20-infected quail. This is in contrast to the distribution of gag-related helper virus proteins lacking myc, which are found only in nonnuclear fractions of superinfected Q8 cells. The purity of unlabeled nuclei was assessed by electron microscopy and enzyme assays, revealing little contaminating material from other subcellular fractions. Immunofluorescence experiments using monospecific anti-gag serum showed specific, intense immunofluorescence in the nuclei of fixed Q8 cells. In contrast, the majority of P75gag-erb, a candidate transforming protein produced by avian erythroblastosis virus (AEV), is absent from the nuclei of nonproducer AEV-transformed chick embryo fibroblasts. The nuclear association of the MC29 transforming protein may be related to some of the unique properties of MC29-transformed cells.
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Haseltine WA, Kleid DG, Panet A, Rothenberg E, Baltimore D. Ordered transcription of RNA tumor virus genomes. J Mol Biol 1976; 106:109-31. [PMID: 61277 DOI: 10.1016/0022-2836(76)90303-x] [Citation(s) in RCA: 139] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
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139 |
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Dittmar KJ, Moelling K. Biochemical properties of p15-associated protease in an avian RNA tumor virus. J Virol 1978; 28:106-18. [PMID: 212597 PMCID: PMC354252 DOI: 10.1128/jvi.28.1.106-118.1978] [Citation(s) in RCA: 104] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
It was observed that the viral structural protein p15 from avian myeloblastosis virus emerges from ion-exchange column chromatography along with a proteolytic activity. p15 is apparently pure, as judged by sodium dodecyl sulfate-polyacryl-amide gel electrophoresis and isoelectric focusing. Increase and decrease in proteolytic activity coincided exactly with increasing and decreasing amounts of p15 during ion-exchange chromatography and during size fractionation by gell filtration. The proteolytic activity cleaved various substrates such as bovine serum albumin, ovalbumin, concanavalin A, and casein after denaturation by sodium dodecyl sulfate and heat. Highest enzyme activity was observed around pH 5.7. As judged from its cleavage pattern and its response to proteolytic inhibitors, the proteolytic activity appears papain-like, and the protease responsible for it may be classified as a thiol protease. If added to immunoprecipitated viral polyprotein precursor Pr76, p15 resulted in cleavage of Pr76,which could be inhibited by antibodies against p15.
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Panet A, Haseltine WA, Baltimore D, Peters G, Harada F, Dahlberg JE. Specific binding of tryptophan transfer RNA to avian myeloblastosis virus RNA-dependent DNA polymerase (reverse transcriptase). Proc Natl Acad Sci U S A 1975; 72:2535-9. [PMID: 52156 PMCID: PMC432803 DOI: 10.1073/pnas.72.7.2535] [Citation(s) in RCA: 102] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
The ability of tryptophan tRNA (tRNATrp) to initiate reverse transcription of the 70S RNA of avian RNA tumor viruses suggested that the reverse transcriptase (RNA-dependent DNA polymerase; deoxynucleosidetriphosphate: DNA deoxynucleotidyltransferase; EC 2.7.7.7) might have a specific binding site for the tRNA. A complex of tRNATrp and the avian myeloblastosis virus reverse transcriptase has been demonstrated using chromatography on Sephadex G-100 columns. Of all the chicken tRNAs, only tRNATrp and a tRNA4Met bind to the enzyme with high enough affinity to be selected from a mixture of the chicken cell tRNAs. The ability of tRNATrp to change the sedimentation rate of the enzyme indicates that tRNATrp is not binding to a contaminant in the enzyme preparation. Treatment of the enzyme with monospecific antibody to reverse transcriptase prevented binding of tRNA as well as inhibited the DNA polymerase activity of the enzyme. The ability of reverse transcriptase to utilize tRNATrp aa a primer for DNA synthesis, therefore, appears to involve a highly specific site on the enzyme.
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Schiff LA, Nibert ML, Fields BN. Characterization of a zinc blotting technique: evidence that a retroviral gag protein binds zinc. Proc Natl Acad Sci U S A 1988; 85:4195-9. [PMID: 3260031 PMCID: PMC280393 DOI: 10.1073/pnas.85.12.4195] [Citation(s) in RCA: 84] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
We have characterized a simple method that uses 65ZnCl2 to detect zinc-binding proteins that have been immobilized on nitrocellulose. Conditions have been identified that permit the detection of as little as 1 microgram of some zinc-binding proteins. The specificity of the binding is indicated by the ability of other divalent metal ions to compete with 65Zn(II) in this assay. We have used this technique to provide evidence that the nucleic acid-binding gag protein of retroviruses also binds zinc. This technique can be applied to biological mixtures of proteins and may be used in proteolytic mapping studies to identify protein fragments that have zinc-binding activity.
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Groudine M, Weintraub H. Activation of cellular genes by avian RNA tumor viruses. Proc Natl Acad Sci U S A 1980; 77:5351-4. [PMID: 6254077 PMCID: PMC350056 DOI: 10.1073/pnas.77.9.5351] [Citation(s) in RCA: 71] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
We demonstrated previously that chicken embryo fibroblasts accumulate approximately 100 copies of embryonic globin RNA after transformation by Rous sarcoma virus. Here we demonstrate that the globin gene in chicken embryo fibroblasts is activated by infection with two other oncogenic retroviruses, avian erythroblastosis virus and strain MC-29 of avian myeloblastosis virus, which contain transforming genes unrelated in nucleotide sequence content to each other or to the Rous sarcoma virus src gene. In addition, we have measured the genetic complexity of transformation by using established techniques for determining the number of different RNA sequences in specific populations of cells. Our results indicate that transformation of chicken embryo fibroblasts by Rous sarcoma virus results in the accumulation of RNA from approximately 1000 average-sized new transcription units.
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Eisenman R, Vogt VM, Diggelmann H. Synthesis of avian RNA tumor virus structural proteins. COLD SPRING HARBOR SYMPOSIA ON QUANTITATIVE BIOLOGY 1974; 39 Pt 2:1067-75. [PMID: 169008 DOI: 10.1101/sqb.1974.039.01.122] [Citation(s) in RCA: 69] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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Jacquet M, Groner Y, Monroy G, Hurwitz J. The in vitro synthesis of avian myeloblastosis viral RNA sequences. Proc Natl Acad Sci U S A 1974; 71:3045-9. [PMID: 4370472 PMCID: PMC388617 DOI: 10.1073/pnas.71.8.3045] [Citation(s) in RCA: 60] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Abstract
Isolated nuclei, prepared from myeloblasts of chicks infected with avian myeloblastosis virus, synthesize RNA sequences present in avian myeloblastosis viral RNA. These sequences are also formed during transcription of chromatin, isolated from myeloblasts, by DNA-dependent RNA polymerases purified from Escherichia coli or calfthymus. In the latter case, transcription is alpha-amanitin sensitive. Formation of hybrids between RNA and avian myeloblastosis virus DNA probes has been monitored by the combined use of ribonucleases A, T(1), and H, and ribonucleases specific for single strands.
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Bading H. Determination of the molecular weight of DNA-bound protein(s) responsible for gel electrophoretic mobility shift of linear DNA fragments examplified with purified viral myb protein. Nucleic Acids Res 1988; 16:5241-8. [PMID: 2968540 PMCID: PMC336764 DOI: 10.1093/nar/16.12.5241] [Citation(s) in RCA: 46] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
A protein-DNA complex has less gel electrophoretic mobility than the free DNA fragment. One parameter for the degree of retardation of a linear DNA fragment in a protein-DNA complex is the molecular weight of the bound protein(s). The quotient of the migration distances of free DNA (m) and protein-DNA complex (m') is a function of the molecular weight (MW) of the bound protein(s). Based on the evaluation of the lac repressor induced mobility shift of a 203 bp DNA fragment containing the lac operator in a 5% non-denaturating polyacrylamide gel a direct proportionality could be shown between (m/m'-1) and MW with the proportionality factor K = 215 kDa. The factor K depends on the acrylamide concentration in the gel, getting lower values with increasing acrylamide concentrations. A calculation is given to determine the molecular weight of DNA-binding factors responsible for the decreased electrophoretic mobility of a linear DNA fragment. As an example this calculation was used in order to analyse DNA-binding of the isolated viral myb protein. It could be demonstrated that the viral myb protein binds to DNA as a monomer and as a dimer.
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Durban EM, Boettiger D. Replicating, differentiated macrophages can serve as in vitro targets for transformation by avian myeloblastosis virus. J Virol 1981; 37:488-92. [PMID: 6260997 PMCID: PMC171026 DOI: 10.1128/jvi.37.1.488-492.1981] [Citation(s) in RCA: 44] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
Pure cultures of chicken macrophages were characterized functionally and transformed by avian myeloblastosis virus. Transformed cells exhibited an altered function. The efficiency of transformation was limited by the mitotic activity of the macrophages.
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Staskus KA, Collett MS, Faras AJ. Initiation of DNA synthesis by the avian oncornavirus RNA-directed DNA polymerase: structural and functional localization of the major species of primer RNA on the oncornavirus genome. Virology 1976; 71:162-8. [PMID: 58468 DOI: 10.1016/0042-6822(76)90102-1] [Citation(s) in RCA: 41] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
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41 |
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Collett MS, Faras AJ. Evidence for circularization of the avian oncornavirus RNA genome during proviral DNA synthesis from studies of reverse transcription in vitro. Proc Natl Acad Sci U S A 1976; 73:1329-32. [PMID: 57620 PMCID: PMC430265 DOI: 10.1073/pnas.73.4.1329] [Citation(s) in RCA: 40] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
The RNA-directed DNA polymerase (deoxynucleosidetriphosphate:DNA deoxynucleotidyltransferase EC 2.7.7.7) of avian oncornavirus requires a tryptophan tRNA (tRNATrp) primer molecule located close to the 5' end of the viral RNA genome for the initiation of DNA synthesis in vitro. In this communication we demonstrate that the DNA product, transcribed from avian myeloblastosis virus (AMV) 35S RNA containing only tRNATrp as primer, is located also at the 5' end of the RNA genome. More importantly, we demonstrate that these 5' terminal DNA transcripts contain nucleotide sequences complementary to the 3' end of the genome. We have interpreted these results to mean that the genome. We have interpreted these results to mean that the 3' and 5' termini of the AMV 35S RNA genome become juxtaposed with each other either before or immediately after DNA synthesis has begun. These results are discussed in regard to the mechanism for synthesis of the circular forms of oncornavirus proviral DNA.
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Steeg CM, Vogt VM. RNA-binding properties of the matrix protein (p19gag) of avian sarcoma and leukemia viruses. J Virol 1990; 64:847-55. [PMID: 2153248 PMCID: PMC249180 DOI: 10.1128/jvi.64.2.847-855.1990] [Citation(s) in RCA: 39] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
We have reinvestigated the ability of the matrix protein (MA) (p19gag) of avian sarcoma and leukemia viruses to interact with RNA. Previous reports claimed on the one hand that MA can bind tightly and with a high degree of specificity to avian sarcoma and leukemia virus RNA in vitro and on the other that it cannot bind to RNA at all. We found that MA purified by any of several methods does bind to RNA, as measured by its ability to cause retention of radioactive RNA on nitrocellulose membranes in a filtration assay. However, this interaction is weak and lacks specificity. The interaction of MA with RNA was barely detectable by classical sedimentation analysis, and from this observation we estimate that the intrinsic MA-RNA association constant is ca. 10(3) M-1, at least 3 orders of magnitude smaller than the constant describing the interaction of the viral nucleocapsid protein (NC) (p12gag) with RNA, ca. 10(6) M-1. Separately purified phosphorylated and nonphosphorylated MA species bound RNA equally. We also found that MA can bind to DNA with an affinity similar to that for RNA. The large quantitative discrepancy between our results and earlier published reports can be traced in part to methods of data analysis.
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Verma IM. Genome organization of RNA tumor viruses. I. In vitro synthesis of full-genome-length single-stranded and double-stranded viral DNA transcripts. J Virol 1978; 26:615-29. [PMID: 209213 PMCID: PMC525887 DOI: 10.1128/jvi.26.3.615-629.1978] [Citation(s) in RCA: 37] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Genome-length complementary DNA (cDNA) transcripts were synthesized in vitro by using purified virions of avian myeloblastosis virus. Moloney murine leukemia virus, and clone 124 mouse sarcoma virus. The size of the genomelenth cDNA transcripts was measured on either alkaline sucrose gradients or alkaline agarose gels. The longest cDNA transcripts synthesized by using avian myeloblastosis virus, Moloney murine leukemia virus, and clone 124 mouse sarcoma virus were 7, 9 and 6 kilobases (kb), respectively. The in vitro system used was capable of synthesizing double-stranded DNA, but the plus strands (same polarity as the viral RNA) were only 0.5 to 1.5 kb long. Lone Moloney murine leukemia virus cDNA transcripts were used as templates to synthesize the second plus strand. Essentially two strategies were employed as follows. (i) The 3' ends of the cDNA transcripts were extended by addition of 50 to 100 dAMP residues by terminal deoxynucleotidyl transferase. The (dA)n-tailed cDNA transcripts were used as templates along with an oligomer of dT as primer and Escherichia coli DNA polymerase to synthesize the plus strands. (ii) DNase-digested calf thymus DNA was used to prime the synthesis of plus strands on long cDNA with E. coli DNA polymerase I. In both cases, the synthesis of the plus strands was monitored by increased resistance of the cDNA templates to single-strand-specific S1 nuclease. The double-stranded DNA was fractionated on neutral sucrose gradients. Analysis of the double-stranded DNA synthesized by using oligo(dT) primer showed the plus strands to be about 5 to 6 kb long, whereas the plus strands synthesized by using DNase-digested calf thymus DNA primers were only 0.3 to 0.5 kb long. Double-stranded DNA synthesized by either method has an average size of 6 x 10(6) daltons. Double-stranded DNA was also synthesized by using cDNA transcripts as templates without the addition of any primers. In this case, the plus strands were covalently linked to the template strand and were not representative of the whole parent strand.
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Pepinsky RB, Papayannopoulos IA, Chow EP, Krishna NK, Craven RC, Vogt VM. Differential proteolytic processing leads to multiple forms of the CA protein in avian sarcoma and leukemia viruses. J Virol 1995; 69:6430-8. [PMID: 7666544 PMCID: PMC189543 DOI: 10.1128/jvi.69.10.6430-6438.1995] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
The CA (capsid) protein of avian sarcoma and leukemia viruses occurs in multiple species. Only one form has been previously characterized biochemically. We have now determined that the mature CA protein of avian sarcoma and leukemia viruses exists as three species with different C termini, ending in amino acid residues A-476, A-478, and M-479 of the Gag precursor, respectively. These structures were deduced from a combination of cyanogen bromide peptide mapping, sequence analysis of tryptic peptides, and electrospray mass spectrometry. The three forms of CA were detected in the same ratios in Rous sarcoma virus and avian myeloblastosis virus and therefore are likely to represent a common feature of members of this genus of avian retroviruses. The only previously reported CA species, CAM-479, accounts for only about 36% of the total CA protein, while CAA-476 and CAA-478 account for 55 and 9%, respectively. From the analysis of peptides cleaved in vitro by PR, the viral protease, we infer that the cleavage site between A-476 and A-477 not only is recognized by PR but is the preferred site. We were unable to determine if A-478/A-479 is a cleavage site for PR or alternatively if CAA-478 results from further processing of CAM-479 by a carboxypeptidase. To study the biological significance of residues A-477 to M-479, we constructed genetically altered viruses in which deletions removed either residues 477 to 479 or 477 to 488. The resulting virus particles appeared to assembly with normal efficiencies, but the latter mutant showed slowed proteolytic processing. Neither of the mutants was infectious.
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Smith BJ, Bailey JM. The binding of an avian myeloblastosis virus basic 12,000 dalton protein to nucleic acids. Nucleic Acids Res 1979; 7:2055-72. [PMID: 231768 PMCID: PMC342366 DOI: 10.1093/nar/7.7.2055] [Citation(s) in RCA: 33] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
The binding of a basic 12,000 dalton protein (p12) from avian myeloblastosis virus to viral RNA and heterologous DNA has been investigated. The binding stoichiometries and constants were determined by an extrinsic fluorescence assay. In both cases each bound p12 molecule occupies four nucleotides and the apparent binding constant is approximately 1 x 10(6) M-1. Binding is non-cooperative and there is no apparent difference in the interaction of p12 with viral RNA or heterologous single-strand DNA. The relative binding constant at various ionic strengths was assayed by the nitrocellulose filter procedure. Analysis of the data revealed that each bound p12 molecule forms three ion pairs with the nucleic acid.
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Abstract
The nuclear protein v-Myb, encoded by the avian myeloblastosis virus (AMV), can induce acute monoblastic leukemia in vivo and transform chicken myelomonocytic cells in culture. The N terminus of v-Myb functions as the DNA-binding domain, and multiple central and C-terminal regions of this protein have been reported to function in transcriptional activation of model reporter genes. We showed previously that a C-terminal domain (amino acids 296 to 371) is required for transcriptional activation and transformation of primary chicken myelomonocytic cells. In this study, we have now analyzed a series of C-terminal mutants of v-Myb to further investigate this domain. A strong correlation was observed between transcriptional activation and leukemic transformation by this series of mutants. Furthermore, deletion analyses demonstrate that the C-terminal 41 amino acids of v=MybAMV (amino acids 331 to 371 of the Myb portion) are nonessential whereas further deletion of amino acids 321 to 330 (EFAETLQLID) results in a nonfunctional protein. Hence, we defined a 10-amino-acid subregion (the "FAETL" motif) required for transcriptional activation and oncogenic transformation by v-Myb Amv. The FAETL region is part of a putative leucine zipper structure and lies near a cluster of phosphorylation sites. Our analysis of mutants with substitutions of the zipper leucines or multiple adjacent phosphorylation sites demonstrates that the function of the FAETL motif is not dependent on an intact leucine zipper structure or adjacent phosphorylation sites. The study of GAL4-Myb fusions suggests that this region is important in maintaining a fully functional conformation of v-Myb. The putative leucine zipper structure has previously been proposed to exert inhibitory effects on c-Myb because its mutation caused increased transcriptional transactivation and transformation. Interestingly, our results show that this region is essential for the functions of v-Myb without requiring a heptad leucine repeat.
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Ghysdael J, Hubert E, Trávnícek M, Bolognesi DP, Burny A, Cleuter Y, Huez G, Kettmann R, Marbaix G, Portetelle D, Chantrenne H. Frog oocytes synthesize and completely process the precursor polypeptide to virion structural proteins after microinjection of avian myeloblastosis virus RNA. Proc Natl Acad Sci U S A 1977; 74:3230-4. [PMID: 198776 PMCID: PMC431509 DOI: 10.1073/pnas.74.8.3230] [Citation(s) in RCA: 27] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
After microinjection of Xenopus laevis oocytes with RNA from avian myeloblastosis virus, viral structural proteins p27, p19, p15, and p12 are formed by a sequence of posttranslational cleavages of a high-molecular-weight precursor polypeptide. The 60-70S RNA aggregate or its 30-40S RNA subunits obtained by heat or formamide treatment possess the same ability to serve as template in X. laevis oocytes. The processing pattern of virus-specific precursor polypeptides is the same in X. laevis oocytes as in chick embryo fibroblasts infected with avian myeloblastosis virus, but the processing takes place at a much slower rate.
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Loeb LA, Sirover MA, Weymouth LA, Dube DK, Seal G, Agarwal SS, Katz E. Infidelity of DNA synthesis as related to mutagenesis and carcinogenesis. JOURNAL OF TOXICOLOGY AND ENVIRONMENTAL HEALTH 1977; 2:1297-304. [PMID: 886629 DOI: 10.1080/15287397709529531] [Citation(s) in RCA: 27] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
An assay system has been developed for measuring the fidelity of DNA synthesis in vitro by using synthetic polynucleotide templates and purified DNA polymerases. Nearest-neighbor analysis of the synthesized product indicates that noncomplementary nucleotides are incorporated as single base substitutions. The accuracy of DNA synthesis can be decreased by (1) prior alkylation of the template, (2) increasing the relative concentration of incorrect nucleotides, and (3) addition of specific metal salts to the reaction mixture. As an initial evaluation of the utility of this system, the effects of 31 metal salts on the fidelity of DNA synthesis have been determined. The results indicate that potential metal mutagens and/or carcinogens may be detected by measuring alterations in the fidelity of DNA synthesis.
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Groner Y, Monroy G, Jacquet M, Hurwitz J. Chromatin as a template for RNA synthesis in vitro. Proc Natl Acad Sci U S A 1975; 72:194-9. [PMID: 1090933 PMCID: PMC432269 DOI: 10.1073/pnas.72.1.194] [Citation(s) in RCA: 27] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
RNA transcribed in vitro from myeloblast chromatin by exogenously added RNA polymerase B predominantly consists of short chains that remain in hybrid structure with the template; the remainder of the product is free RNA of heterogeneous size. Addition of polyanions during synthesis caused an increase in the size and amount of free RNA with a concomitant decrease in the proportion of small RNA. The large molecular weight RNA is derived from the short RNA chains, which are synthesized de novo during the reaction in vitro. The effect of polyanions on the size and nature of the product may be related to structural changes induced in the template rather than to an inhibition of nuclease activity.
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Pepinsky RB, Mattaliano RJ, Vogt VM. Structure and processing of the p2 region of avian sarcoma and leukemia virus gag precursor polyproteins. J Virol 1986; 58:50-8. [PMID: 3005658 PMCID: PMC252875 DOI: 10.1128/jvi.58.1.50-58.1986] [Citation(s) in RCA: 26] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
We have purified two low-molecular-weight polypeptides from the Prague C strain of Rous sarcoma virus and have identified these as products of the gag precursor Pr76 by protein sequencing and by amino acid analysis. Both polypeptides are derived from a stretch of 22 amino acids within Pr76 that separates p19 and p10. We refer to this region as p2. Together the two cleavage products form the entire p2 region. The junctions of p19 with the amino-terminal fragment of p2 and of p10 with the carboxy-terminal fragment of p2 define two new processing sites within the gag precursor, Tyr-155-His-156 and Gly-177-Ser-178. Both polypeptides are major cleavage products of Pr76 that occur in Prague C Rous sarcoma virus at an estimated 1,000 copies per virion. They also are prominent components of avian myeloblastosis virus. The combination of gel filtration and reverse-phase high-pressure liquid chromatography, which was used for the isolation of the two fragments of p2, resolved over a dozen other low-molecular-weight polypeptides from avian sarcoma and leukemia viruses that previously were undetected. This technique thus should serve as a useful procedure for further characterization of viral components.
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Olsen JC, Watson KF. Reverse transcription of avian myeloblastosis virus 35S RNA. Early synthesis of plus strand DNA of discrete size in reconstructed reactions. Nucleic Acids Res 1982; 10:1009-27. [PMID: 6174940 PMCID: PMC326217 DOI: 10.1093/nar/10.3.1009] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023] Open
Abstract
The early DNa products of reverse transcription have been analyzed from reconstructed reactions containing avian myeloblastosis virus 35S RNA . tRNAtrp complex and highly purified reverse transcriptase. We describe conditions for the synthesis of genome-length complementary DNA and two discrete species of plus strand DNA (the same chemical polarity as the viral RNA genome) about 300 and 400 nucleotides in length. Plus DNA400 and plus DNA300 were detected by molecular hybridization with DNA probes complementary to sequences from both the 3'- and 5'-ends of the viral RNA. Both species appear to be copied from the 5'-end of minus strand DNA by their hybridization properties and their early synthesis when only the 5'-end of minus strand DNA is available as template. Restriction endonuclease mapping of plus DNA400 and plus DNA300 rules out a precursor-product relationship between the two. Rather the results suggest a unique initiation site for both species, with plus DNA400 containing internal sequences not present in plus DNA300. Plus DNA400 and plus DNA300 appear to be analogous to early plus DNA species detected in cells early after retrovirus infection. Thus, purified reverse transcriptase appears to be enzymatically sufficient for synthesis of genome-length complementary DNA and initiation and synthesis of early plus strand DNA as observed in infected cells.
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Rapaport E, Svihovec SK, Zamecnik PC. Relationship of the first step in protein synthesis to ppGpp: formation of A(5')ppp(5')Gpp. Proc Natl Acad Sci U S A 1975; 72:2653-7. [PMID: 170611 PMCID: PMC432828 DOI: 10.1073/pnas.72.7.2653] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
In the presence of purified Escherichia coli lysyl-tRNA synthetase [L-lysine:tRNALys ligase (AMP-forming) EC 6.1.1.6], L-lysine, and ATP, addition of the nucleotide ppGpp results in formation of a unique product-A(5')ppp(5') Gpp. The same compound is also formed very rapidly in a cell-free protein-synthesizing system when ppGpp is added. The possible significance of this reaction in the rapid turnover of ppGpp and as a more general mechanism by which an AMP residue is activated and introduced onto a 5'-diphosphorylated species, including the 5'-end of an RNA, is further discussed.
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Salden M, Asselbergs F, Bloemendal H. Translation of oncogenic virus RNA in Xenopus laevis oocytes. Nature 1976; 259:696-99. [PMID: 175294 DOI: 10.1038/259696a0] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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