Expression and activity of a recombinant chimeric protein composed of pokeweed antiviral protein and of human interleukin-2

Abstract

The pokeweed antiviral protein (PAP) has already been used to chemically construct immunotoxins. Here we tested the recombinant approach for the production of PAP-containing cytotoxic fusion-proteins. A cDNA encoding a mutated PAP (PAP9), which is expressed at high levels in bacteria, was fused to human interleukin-2 (IL-2) cDNA. The resulting PAP9–IL-2 protein was as active as the free PAP9 in inhibiting an eukaryotic cell-free translation system. Only the chimeric protein desaminated the 28S rRNA and inhibited translation of the CTLL-2 cell line which expresses the IL-2 receptor. These results show that PAP is a suitable toxin for the production of recombinant immunotoxins.