Search PubMed⌕ Search

Biomedical subjects

J B Lewis

Publications and source records attributed to J B Lewis.

At least 91 records · Page 5Linked to original sources
PubMed1979

Characterization of a fused protein specified by the adenovirus type 2-simian virus 40 hybrid Ad2+ND1 dp2.

The adenovirus type 2-simian virus 40 (SV40) hybrid virus Ad2+ND1 dp2 (E. Lukanidin, manuscript in preparation) specified two proteins (molecular weights, 24,000 and 23,000) that are, in part, products of an insertion of SV40 early DNA sequences. This was demonstrated by translation in vitro from viral mRNA that had been selected by hybridization to SV40 DNA. These two phosphorylated, nonvirion proteins were produced late in infection in amounts similar to adenovirus 2 structural proteins and were closely related to each other in tryptic peptide composition. The portion of SV40 DNA (map units 0.17 to 0.22 on the SV40 genome) coding for these proteins was joined to sequences coding for the amino-terminal part of the adenovirus type 2 structural protein IV (fiber). The Ad2+ND1 dp2 23,000- and 24,000-molecular-weight proteins were hybrid polypeptides, with about two-thirds of their tryptic peptides contributed by the fiber protein and the remainder contributed by SV40 T-antigen. They shared with T-antigen (molecular weight, 96,000) a carboxy-terminal proline-rich tryptic peptide. Together, the tryptic peptide composition of these proteins and the known SV40 DNA sequences suggested the reading frame for the translation of T-antigen. The carboxy terminus for T-anigen would then be located on the SV40 genome map next to the TAA terminator triplet at position 0.175, 910 bases away from the cleavage site of the restriction endonuclease EcoRI. Seven host range mutants from Ad2+ND1 dp2 were isolated that had lost the capacity to propagate on monkey cells. They did not induce detectable levels of the hybrid proteins. Three of these mutants had lost the SV40 DNA insertion that codes in part for these proteins. Thus, in analogy to the Ad2+ND1 30,000-molecular-weight protein, the presence of these proteins correlates with the presence of the helper function for adenovirus replication on monkey cells.

Adenoviruses, Human↗
PubMed1979

Adenovirus type 2 terminal protein: purification and comparison of tryptic peptides with known adenovirus-coded proteins.

The protein covalently bound to the 5' termini of adenovirus type 2 DNA has been purified from virus labeled with [35S]methionine, using exclusion chromatography of disrupted virions to isolate the DNA-protein complex, which is then digested with DNase. The terminal protein isolated from mature virus is most effectively labeled if the cells are exposed to [35S]methionine during the "intermediate" period of 13 to 21 h postinfection, suggesting that the protein is synthesized during this interval. The tryptic peptides of the terminal protein were compared with those of several known adenovirus-coded proteins and found to be unrelated. In particular, the terminal protein is not related to the 38-50K early proteins encoded by the leftmost 4.4% of the adenovirus genome, one region essential for the transforming activity of the virus. Neither is it related to the 72K single-strand-specific DNA binding protein, the minor virion component IVa2, or the major capsid component hexon.

Adenoviruses, Human↗
PubMed1978

Adenovirus type 2 early proteins synthesized in vitro and in vivo: identification in infected cells of the 38,000- to 50,000- molecular-weight protein encoded by the left end of the adenovirus type 2 genome.

Analysis by sodium dodecyl sulfate-polyacrylamide gel electrophoresis of protein synthesized early after injection of human cells with adenovirus type 2 (Ad2) showed that polypeptides of 11,000 (11K), 12K, 14K, 15K, 19K, 21K, 24K, and 72k molecular weight were present in infected but not in mock-infected cells. These polypeptides corresponded in electrophoretic mobility to the following polypeptides synthesized in vitro by using mRNA complementary to specific regions of the Ad2 genome: 11K, 19K, 21K (91.5 to 96.8 map units), 14K (78.2 to 83.4 map units), 72K (62.4 to 67.9 map units), and 15K (4.9 to 11.0 map units). Polypeptides of 25K, 17K, 15.5K, and 13K were also synthesized in vitro, but have not yet been detected in infected cells. In addition, six adeno-specific polypeptides of 38 to 50K molecular weight could be discerned in infected cells if two-dimensional isoelectric focusing-polyacrylamide gel electrophoresis was used to compare extracts from infected and mock-infected cells. Partial protease digestion showed these 38 to 50K polypeptides to be related in sequence to each other and to the 40 to 50K polypeptide made in vitro (1.3 to 4.0 map units).

Adenoviruses, Human↗
PubMed1977

Further mapping of late adenovirus genes by cell-free translation of RNA selected by hybridization to specific DNA fragments.

RNA isolated from the cytoplasm of human cells at late times after infection by adenovirus type 2 (Ad2) has been fractionated by hybridization to fragments of Ad2 DNA which were produced by digestion with the restriction endonucleases Hpa I, Eco RI, Bam HI and Hind III. Cell-free translation of these partially purified mRNAs indicates that the genes for the late Ad2 proteins lie within the following intervals on the conventional Ad2 map: 15K (4.4-17.0 map units), IX and IVa2 (7.5-17.0), IIIa (29.1-40.9), III and V (29.1-57.0), pVIII (40.9-57.0), pVI and II (40.9-70.7), 100K (59.0-83.4), pVIII (70.7-83.4) and IV (85.0-100). In addition to the primary hybridization of the late Ad2 mRNAs to the regions indicated above, most late Ad2 mRNAs (except those for 15K, IX and IVa2) exhibited some hybridization to a secondary site between 17.0 and 29.1 map units.

Adenoviruses, Human↗
PubMed1977

Identification of amber and ochre mutants of the human virus Ad2+ND1.

Although human adenoviruses grow poorly in monkey cells, this defect can be overcome either by coinfection of cells with simian virus 40 (SV40) or by insertion of the relevant portion of the SV40 genome into the adenovirus genome to form an adenovirus-SV40 hybrid virus. The nondefective adenovirus-2-SV40 hybrid virus, Ad2+ND1, contains an insertion of 17% of the SV40 genome, which codes for at least part of a 30,000 dalton protein. A set of Ad2+ND1 host-range mutants that have lost the ability to grow in monkey cells and behave as point mutants fail to synthesize the 30,000 dalton ND1 protein. Translation in vitro of SV40-specific mRNA from mutant-infected cells produces unique short polypeptides instead of the 30,000 dalton protein. Here we show that this set of host-range mutants includes both ochre and amber nonsense mutations. When the SV40-specific mRNA from the host-range mutants is translated in vitro to produce the polypeptide fragments, yeast suppressor tRNA can partially restore synthesis of wild-type-size 30,000 dalton protein. By this assay, one mutant is ochre and two are amber.

Adenoviridae↗
PubMed1976

Location and identification of the genes for adenovirus type 2 early polypeptides.

Virus-specific RNA was prepared from cells early after adenovirus type 2 infection and fractionated by hybridization to specific fragments of viral DNA. The viral mRNA was used to program cell-free protein synthesis, and the products were analyzed by electrophoresis. The genes for the early polypeptides of apparent molecular weight 44,000, 15,000, 72,000, 15,500, 19,000, and 11,000 daltons were located, respectively, between positions 0-4.1, 4.1-16.7, 58.5-70.7, 75.9-83.4, 89.7-98.6, and 89.7-98.6 of the conventional adenovirus DNA map. The polypeptide of molecular weight 72,000 daltons was shown to be the single-stranded DNA-binding protein described by others. RNAs from three different adeno-transformed cell lines each program the synthesis in vitro of predominantly the 15K polypeptide, as well as variable amounts of the polypeptide of molecular weight 44,000 daltons. The genes for these two polypeptides are located in the portion of DNA known to be required for transformation of rodent cells by adenovirus.

Adenoviridae↗
PubMed1976

Simian virus 40-specific polypeptides in AD2+ ND1- and Ad2+ ND4-infected cells.

A comparison of the proteins synthesized in human cells at late times after infection with adenovirus (Ad2) and with the adeno-simian virus 40 (SV40) hybrid viruses revealed polypeptides of 30,000 and 92,000 molecular weight specific for the hybrid viruses Ad2+ND1 and Ad2+ND4, respectively. Cell-free translation of SV40-specific mRNA, prepared from these cells by hybridization of total cytoplasmic RNA to SV40 DNA, showed that the mRNA's specifying these two polypeptides were at least partially encoded by the SV40 portion of the hybrid viruses. Cell-free translation of SV40-specific mRNA prepared from monkey cells infected with SV40 produced polypeptides of 40,000, 43,000, 48,500, and 92,000 molecular weight. The SV40 and Ad2+ND4 92,000-molecular-weight polypeptides made in vitro were very similar in electrophoretic mobility in sodium dodecyl sulfate-polyacrylamide gels to the polypeptide precipitated by Tegtmeyer (1974) with SV40 anti-T serum.

Adenoviridae↗
PubMed1976

Conditional lethal mutants of adenovirus type 2-simian virus 40 hybrids. II. Ad2+ND1 host-range mutants that synthesize fragments of the Ad2+ND1 30K protein.

Adenovirus type 2 (Ad2) grows 1,000 times less well in monkey cells than in human cells. This defect can be overcome, not only upon co-infection of cells with simian virus 40 (SV40), but also when the relevant part of the SV40 genome is integrated into the adenovirus genome to form an adenovirus-SV40 hybrid virus. We have used the nondefective Ad2-SV40 hybrid virus Ad2+ND1, which contains an insertion of 17% of the SV40 genome, to isolate host-range mutants which are defective in growth on monkey cells although they grow normally on human cells. Like Ad2, these mutants are defective in the synthesis of late proteins in monkey cells. A 30,000-molecular-weight protein (30K), unique to Ad2+ND1-infected cells, can be synthesized in vitro, using Ad2+ND1 mRNA that contains SV40 sequences. 30K is not seen in cells infected with those host-range mutants that are most defective in growth on monkey cells, and translation in vitro of SV40-specific mRNA from these cells produces new unique polypeptides, instead of 30K. Genetic and biochemical analyses indicate that these mutants carry point mutations rather than deletions.

Adenoviridae↗
PubMed1975

Enhanced differential synthesis of proteins in a mammalian cell-free system by addition of polyamines.

Addition of the polyamines spermidine, spermine, or putrescine to a fractionated mammalian cell-free protein-synthesis system programmed by a variety of mRNAs results in a 3- to 5-fold stimulation of amino acid incorporation over that found in the absence of added polyamine. The mRNAs used as template were adenovirus mRNA, globin 9s mRNA, and RNA from the bacteriophages R17, Qbeta, and MS2. The relative amounts of 10 adenovirus polypeptides synthesized in vitro are altered by the addition of polyamines to the translation system to reflect more closely the relative amounts of these polypeptides synthesized in vivo. This qualititive improvement in translation products on addition of polyamines allow the analysis of a number of products which are at best only marginally synthesized in the absence of added polyamines. The low level of synthesis due to endogenous mRNA is stimulated by spermidine and spermine but a lesser extent by putrescine.

Animals↗
PubMed1975

A comparison of the binding to polynucleotides of complementary and noncomplementary oligonucleotides.

The binding of oligonucleotides to synthetic polynucleotides has been studied as a control for investigations of the binding of oligonucleotides to natural RNA molecules. Only combinations that involved A-U, G-C, and G-G pairs were found to be significantly stable under the experimental conditions used here. The stability of the oligomerpolymer pairing increased with the length of the region paired and with its G + C content. Further, some different sequence isomers of the same G + C content exhibited quite different binding constants. This variability is consistent with certain sequence differences in the double-strand stacking interactions stabilizing the oligomer-polymer association. Oligomer binding was also shown to depend upon the identity of the polymer residues neighboring the binding site, indicating the effect upon oligomer binding of small changes in the single-strand conformation of the binding site. These observations validate the criteria that allow one to decide if an observed association constant of an oligomer to an RNA molecule reflects a complete complementarity between the two or not. This improves the basis for using oligonucleotide binding constants to RNA of known sequences to map secondary structure.

Adenine Nucleotides↗
PubMed1975

Mapping of late adenovirus genes by cell-free translation of RNA selected by hybridization to specific DNA fragments.

Cytoplasmic RNA, isolated from cells late after infection by adenovirus type 2 and fractionated by hybridization to specific fragments of adenovirus DNA produced by cleavage with the endonuclease R-EcoRI, was used as template for protein synthesis in cell-free mammalian extracts. Each of the R-EcoRI fragments of DNA selects RNA that encodes specific subsets of the viral polypeptides. From the known order of the R-EcoRI fragments, the following partial map is deduced: (III, IIIa, IVa2, V, P-VII, IX), (II, P-VI), 100K, IV-where the relative order of the components enclosed in parentheses has not yet been determined.

Adenoviridae↗