RESUMO
Cell-free translation in Krebs-2 extracts was optimized for RNAs of two plant viruses; potato virus X (PVX, potexvirus), and tobacco mosaic virus (TMV, tobamovirus). PVX and TMV RNAs programmed synthesis of similar sets of polypeptides in both the Krebs-2 extracts and the rabbit reticulocyte lysates, major virus-specific products being the same in molecular weight in both in vitro systems. PVX structural protein (p29) was absent among polypeptides synthesized in the Krebs-2 system but was readily identified by immuno-precipitation among the ones synthesized in the reticulocyte lysate system. The "cap" analog, m7Gpp, inhibited the synthesis of all the polypeptides programmed by PVX RNA in the Krebs-2 system. The synthesis of only a few of the most high molecular weight products in the reticulocyte lysate system was inhibited, the synthesis of a number of low molecular weight products (and among them p29) was even stimulated. Thus, the PVX capped messengers derived from PVX genomic RNA due to its fragmentation with endogenous nuclease activities. The use of the Krebs-2 system allows to avoid activation of internal PVX genes.
Assuntos
Carcinoma Krebs 2/genética , Vírus de Plantas/genética , Biossíntese de Proteínas , RNA Viral/genética , Animais , Carcinoma Krebs 2/metabolismo , Sistema Livre de Células , Eletroforese em Gel de Ágar , Peso Molecular , Coelhos , Reticulócitos/metabolismo , Células Tumorais CultivadasRESUMO
The diversity of primary structures of cellular and virus mRNAs was considered from the standpoint of their functioning at the initial stops of translation. The number and reciprocal localization of the open translational frames along the mRNAs, and also the number, localization and nucleotides surroundings the initiation codons were analysed. The structural organizations of the polycistronic and other non-canonical forms of native mRNAs, translated in eukaryotic cells, were considered and classified. The possible mechanisms of translation initiation by different forms of mRNAs are discussed.
Assuntos
Biossíntese de Proteínas , RNA Mensageiro/genética , Sequência de Bases , Códon , Células EucarióticasRESUMO
Inhibition of the synthesis of virus-specific proteins of influenza A/WSN/33 virus in the cells of chick embryo fibroblasts and in continuous cells of dog embryonal kidney was discovered as was a negligible inhibition of the synthesis of cell proteins in the presence of an original synthetic antivirus drug bonaphthon. Experiments were made to attain selective inhibition of individual virus-specific proteins of influenza virus in these cultures. In model experiments in vitro in a cell-free protein-synthesizing system, bonaphthon was demonstrated to inhibit translation of RNA-virus of encephalomyocarditis on the virus template without affecting translation on the cell template of hemoglobin mRNA.
Assuntos
Vírus da Encefalomiocardite/metabolismo , Vírus da Influenza A/metabolismo , Naftoquinonas/farmacologia , Proteínas Virais/biossíntese , Animais , Embrião de Galinha , Meios de Cultura , Cães , Embrião de Mamíferos , Feminino , Fibroblastos , Técnicas In Vitro , Rim , GravidezAssuntos
Carcinoma Krebs 2/genética , Infecções por Enterovirus/genética , Biossíntese de Proteínas/efeitos dos fármacos , Animais , Carcinoma Krebs 2/metabolismo , Carcinoma Krebs 2/microbiologia , Vírus da Encefalomiocardite/genética , Infecções por Enterovirus/metabolismo , Infecções por Enterovirus/microbiologia , Técnicas In Vitro , Camundongos , Proteínas de Neoplasias/biossíntese , RNA Mensageiro/genética , RNA Neoplásico/genética , RNA Viral/genéticaRESUMO
A single injection of N-methyl-N-nitrosourea results in simultaneous long-term inhibition of tumor growth and protein synthesis in mouse hepatoma 22a cells. These effects are tightly connected: onset of tumor regrowth starts only after a full recovery of the activity of the protein synthetic machinery of tumor cells.
