Mutations dissociating the inhibitory activity of the pokeweed antiviral protein on eukaryote translation and Escherichia coli growth.

The pokeweed antiviral protein is a ribosome inactivating protein acting on eukaryotic as well as on prokaryotic ribosomes thus is toxic for both cell types. Using the PCR technique to clone the PAP open reading frame, we characterized two cDNAs coding for proteins inhibiting eukaryotic translation process and which are not toxic for Escherichia coli, unlike the wild type protein. The sequence of the two cDNAs showed that the proteins contain only one and two point mutations. This result suggest that the wild type amino acids in the mutated positions participate in the prokaryotic ribosome recognition. These mutants might be useful for the construction of immunotoxins containing the pokeweed antiviral protein as toxin.