Interferon-induced translation defects in a cell-free protein-synthesizing system from mouse erythroleukemia cells

The mechanism of the interferon-induced translation inhibition was studied in vitro using a fractionated cell-free protein-synthesizing system prepared from Friend virus-transformed mouse erythroleukemia cells and L cells. The soluble fraction of the system was prepared from nonpreincubated S30 lysates. To lower endogenous protein synthesis, the ribosomes were prepared from extracts treated with micrococcal nuclease at 20°. If the components were prepared from interferon-treated cells, viral and cellular mRNA translation was inhibited. In the cell-free system prepared from interferon-treated mouse erythroleukemia cells, the translation defect could be localized in the high-speed supernatant, while ribosomes from interferon-treated and control cells were of comparable activity. In contrast, ribosomes from interferon-treated L cells prepared by the same method were unable to support translation of exogenous mRNAs. The interferon-induced translational defect in either cell-free system could not be overcome by adding tRNA. Aminoacylation and stability of endogenous leucine-specific tRNAs was not impaired in the high-speed supernatant of both of the cell-free systems from interferon-treated cells.