Abstract
The roles of the L and NS polypeptides in transcription by vesicular stomatitis virus New Jersey were studied using a mutant, tsE1, which contains a temperature-sensitive transcriptase and an altered NS polypeptide, both phenotypic changes being the consequence of the ts mutation. Mutant tsE1, its revertant (tsE1/R1) and the wild-type virus were dissociated into sub-viral fractions and, after reconstitution of these fractions in all combinations, the transcriptase was assayed in vitro at the permissive (31 °C) and restrictive (39 °C) temperatures. Reconstitution of the pellet fractions (containing polypeptide N complexed with the virion RNA) and the supernatant fractions (containing polypeptides L and NS) restored transcriptase activity at 31 °C in all combinations, but at 39 °C transcription was observed only in the presence of the supernatant fractions of wild-type and revertant viruses but not in the presence of the supernatant fractions of tsE1. When the pellet fractions and the L fractions were reconstituted, the transcriptase activity was restored in all combinations both at 31 °C and 39 °C. However, in vitro transcription at 39 °C by reconstituted pellet and L fractions was strongly inhibited when the NS fraction of tsE1 was also added, while addition of the NS fractions of wild-type and revertant viruses had no effect. Since only traces of polypeptide NS were present in the L fractions and none in the pellet fractions, the results strongly suggest that polypeptide L is the transcriptase itself while polypeptide NS exerts some control over transcription.