Requirements and functions of vesicular stomatitis virus L and NS proteins in the transcription process in vitro

The L and NS proteins of vesicular stomatitis virus were purified from transcribing ribonucleoprotein complex and were used to study their requirements and functions during reconstitution of RNA synthesis in vitro. The requirements for L and NS proteins for optimal RNA synthesis were found to be catalytic and stoichiometric, respectively. Addition of increasing amounts of NS protein to N-RNA template and saturating L protein, the ratio of N-mRNA to leader RNA synthesis increased linearly. In contrast, when the concentration of L protein was increased the corresponding ratio remained constant. These results, coupled with the observation that the L protein is involved in the initiation of RNA synthesis, suggest that the NS protein is involved in the RNA chain elongation step. The NS protein possibly interacts with both the L protein and the template N-RNA and unwinds the latter to facilitate the movement of L protein on the template RNA.