Cell-free translation of RNA synthesized in vitro by a transcribing nucleoprotein complex prepared from purified vesicular stomatitis virus

Inhibition of vesicular stomatitis virus protein synthesis and infection by sequence-specific oligodeoxyribonucleoside methylphosphonates

Oligodeoxyribonucleoside methylphosphonates which have sequences complementary to the initiation codon regions of N, NS, and G vesicular stomatitis virus (VSV) mRNAs were tested for their ability to inhibit translation of VSV mRNA in a cell-free system and in VSV-infected mouse L cells. In a rabbit reticulocyte lysate cell-free system, the oligomers complementary to N (oligomer I) and NS (oligomer II) mRNAs inhibited translation of VSV N and NS mRNAs whereas oligomer III had only a slight inhibitory effect on N protein synthesis. At 100 and 150 microM, oligomer I specifically inhibited N protein synthesis in the lysate. In contrast, at 150 microM, oligomer II inhibited both N and NS protein synthesis. This reduced specificity of inhibition may be due to the formation of partial duplexes between oligomer II and VSV N mRNA. The oligomers had little or no inhibitory effects on the synthesis of globin mRNA in the same lysate system. Oligomers I-III specifically inhibited the synthesis of all five viral proteins in VSV-infected cells in a concentration-dependent manner. The oligomers had no effects on cellular protein synthesis in uninfected cells nor on cell growth. An oligothymidylate which forms only weak duplexes with poly(rA) had just a slight effect on VSV protein synthesis and yield of virus. Oligomers I-III have extensive partial complementarity with the coding regions of L mRNA. The nonspecific inhibition of viral protein synthesis in infected cells may reflect the role of N, NS, and/or L proteins in the replication and transcription of viral RNA or result from duplex formation between the oligomers and complementary, plus-strand viral RNA.(ABSTRACT TRUNCATED AT 250 WORDS)

Possible involvement of poly(A) in protein synthesis

The experiments of this paper have re-evaluated the possibility that poly(A) is involved in protein synthesis by testing whether purified poly(A) might competitively inhibit in vitro protein synthesis in rabbit reticulocyte extracts. We have found that poly(A) inhibits the rate of translation of many different poly(A)+ mRNAs and that comparable inhibition is not observed with other ribopolymers. Inhibition by poly(A) preferentially affects the translation of adenylated mRNAs and can be overcome by increased mRNA concentrations or by translating mRNPs instead of mRNA. The extent of inhibition is dependent on the size of the competitor poly(A) as well as on the translation activity which a lysate has for poly(A)+ RNA. In light of our results and numerous experiments in the literature, we propose that poly(A) has a function in protein synthesis and that any role in the determination of mRNA stability is indirect.

Temperature-sensitive mutants of complementation group E of vesicular stomatitis virus New Jersey serotype possess altered NS polypeptides

In vesicular stomatitis virus New Jersey serotype polyacrylamide gel electrophoresis was unable to distinguish the polypeptides of the temperature-sensitive (ts) mutants of complementation groups A, B, C, and F from those of the wild-type virus. However, the NS polypeptide of the representative mutant of group E, ts E1, had a significantly greater electrophoretic mobility than that of the wild-type virus NS polypeptide. The electrophoretic mobilities of the NS polypeptides of the three mutants of complementation group E varied, being greatest in the case of ts E1, slightly less for ts E2, and only a little greater than that of wild-type virus NS polypeptide in the case of ts E3. Since the NS polypeptides of the revertant clones ts E1/R1 and ts E3/R1 have mobilities identical to that of wild-type NS polypeptide, the observed altered mobilities of the group E mutants are almost certainly the direct result of the ts mutations in the E locus. The electrophoretic mobilities of the intracellular NS polypeptides of the group E mutants were indistinguishable from those of their virion NS polypeptides. The electrophoretic mobilities of the NS polypeptides of the group E mutants synthesized in vitro using mRNA synthesized in vitro by TNP were identical to those of the NS polypeptides of their purified virions. The NS polypeptides of all three mutants were labeled with (32)P(i) to approximately the same extent as wild-type virus NS polypeptide, indicating that gross differences in phosphorylation of this polypeptide are unlikely to account for the altered mobilities. We propose a model in which the NS polypeptide consists of at least three loops held in this configuration by hydrophobic or ionic forces or both and stabilized by phosphodiester bridges. If a mutation affects one of the amino acids to which the phosphate is covalently linked, the phosphodiester bridge cannot be formed, and, as a result, in the presence of sodium dodecyl sulfate the affected loop opens and thus the NS polypeptide migrates further into the gel. Such a configuration may also explain the multifunctional nature of the NS polypeptide.

Effect of temperature-sensitive mutation on activity of the RNA transcriptase of vesicular stomatitis virus New Jersey

The virion-associated RNA transcriptase activity of vesicular stomatitis virus New Jersey temperature-sensitive (ts) mutants was assayed in vitro at the permissive (31 degrees C) and restrictive (39 degrees C) temperatures. RNA synthesis at 39 degrees C by the RNA-negative ts A1 and the RNA-positive ts C1 and ts D1 mutants was similar to that of wild-type virus. The RNA-negative ts B1 synthesized only small amounts of RNA in vitro at 39 degrees C. The three mutants of complementation group E were dissimilar in the amounts of RNA they synthesized at 39 degrees C: ts E1 synthesized very little RNA, ts E2 synthesized moderate amounts, and RNA synthesis by ts E3 was not inhibited. The two mutants of group F were also dissimilar, since ts F1 synthesized very little RNA at 39 degrees C, whereas ts F2 synthesized as much RNA as wild-type virus. The revertant clones ts B1/R1, ts E1/R1, and ts F1/R1 synthesized RNA at 39 degrees C in amounts comparable to wild-type virus, indicating that the heat sensitivity of the transcriptase activity of the mutants ts B1, ts E1, and ts F1 was associated with temperature sensitivity. Similar heat sensitivities were observed when transcribing nucleoprotein complexes were used in the assays, showing that the mutated polypeptides were part of the viral core. The heat stability of the mutant ts B1 was similar to that of wild-type virus, and in vitro RNA synthesis was fully restored when the temperature was lowered to 31 degrees C after 30 min of preincubation at 39 degrees C, showing that the inhibition was due to reversible configurational change of the mutated polypeptide. When virions of the mutant ts E1 were heated for 5 h at 39 degrees C, their infectivity and transcriptase activity were as stable as those of the wild-type virus, whereas transcriptase activity became very heat labile after disruption of the viral coat with a neutral detergent. This suggests an interaction between the mutated polypeptide and a coat polypeptide which stabilizes the activity of the transcriptase. The RNA transcriptase activity of the mutant ts F1 was also heat labile, although to a lesser extent than that of ts E1. Thus, the defects in transcriptase activity of groups B, E, and F suggest that all three polypeptides of the virus core, polypeptides L, N, and NS, are involved in the transcription. In addition, we postulate that the mutated gene products of groups E and F are multifunctional, being required both in transcription and replication, and that the gene product of group E may also be involved in some late stage of virus development.

Analysis of the 3'-terminal nucleotide sequence of vesicular stomatitis virus N protein mRNA

The sequence of 205 nucleotides adjacent to the poly(A) tract at the 3'-terminus of the mRNA encoding the N polypeptide of vesicular stomatitis virus has been determined by copying with reverse transcriptase and using 2', 3'-dideoxynucleoside triphosphates as specific chain terminators. The method appears highly suitable for sequence determination in any purified mRNA. An examination of the sequence did not locate without ambiguity the limit of polypeptide coding RNA. The hexanucleotide AAUAAA, previously found in all poly(A)-containing eukaryote mRNAs, is not present, although the sequence immediately adjacent to the 3'-terminal poly(A) has a high content of A+U.

Peptide mapping characterization of viral proteins generated in a cell-free coupled system for the transcription and translation of influenza virus mRNA

In a coupled cell-free system for the transcription and translation of the influenza mRNA's, containing detergent-disrupted purified NWS influenza virion and a micrococcal nuclease-preincubated rabbit reticulocyte lysate, five unglycosylated viral proteins (NS1, M, NP, P1, and P3) were easily produced and isolated. Their identification was based on the electrophoretic separation of peptide fragments resulting from their partial digestion with proteases of restricted specificity (D.W. Cleveland, S. G. Fisher, N. W. Kirschner, and U. K. Laemmli, J. Biol. Chem. 252:1102-1106, 1977).

Cell-free synthesis of herpes simplex virus-coded pyrimidine deoxyribonucleoside kinase enzyme

The incubation of a cell-free protein-synthesizing system prepared from rabbit reticulocytes with cytoplasmic RNA from herpes simplex virus (HSV)-infected cells resulted in increased thymidine kinase activity. This enzyme activity was specifically inhibited by anti-HSV antiserum and was relatively unaffected by TTP, an inhibitor of cellular thymidine kinases. Induction of the new activity was prevented by addition of inhibitors of eucaryotic protein synthesis, and no new activity was detected when RNA from cells infected with pyrimidine deoxyribonucleoside kinase-deficient mutants, instead of wild-type HSV, was added. An increased deoxycytidine kinase activity with similar properties to the HSV-specified enzyme activity was also present in cell-free systems incubated with RNA from HSV-infected cells. Phosphorylation of thymidine and deoxycytidine at 30 degrees C continued for longer than 11 h. The findings are consistent with the accurate synthesis in vitro of enzymically active HSV-specified pyrimidine deoxyribonucleoside kinase.