Isolation and characterization of a cDNA clone encoding the pokeweed antiviral protein II from Phytolacca americana and its expression in E. coli

Abstract

Three distinct ribosome-inactivating proteins (RIPS) were isolated from pokeweed (Phytolacca americana). We identified and sequenced for the first time a complete cDNA encoding the pokeweed antiviral protein II (PAP II), which is expressed in the late summer leaves of pokewecd. The cDNA of PAP II consists of 1,187 nucleotides and encodes a mature protein of 285 amino acids. Its predicted amino acid sequence is only 33% similar to PAP and PAP-S. The NH2 terminal extrapeptide (25 amino acid residues) was similar but not identical to that of PAP's extrapeptide. The cDNA of PAP II was expressed in E. coli. The growth of the transformants was strongly inhibited after induction of the gene. Furthermore, PAP II, which was produced in E. coli, inhibited protein synthesis in a rabbit reticulocyte translation system. Thus, recombinant PAP II would appear to be as functional as native PAP in inhibiting protein synthesis in both prokaryotes and eukaryotes.

Cloning and expression of antiviral/ribosome-inactivating protein from Bougainvillea xbuttiana

“…As discussed earlier (section 3.3), this might be due to the presence of a signal peptide. Similar results have been reported for MAP (Kataoka et al 1991), PAP II (Poyet et al 1994), bouganin (Hartog et al 2002 and…”

Insights into the Molecular Antiviral Mechanism of Pokeweed Protein from Phytolacca americana

“…It has been postulated that a direct interaction of PAP with viral RNA (or DNA) is an alternative antiviral mechanism in play. The pokeweed plant produces several isozymes of PAP, all exerting potent antiviral properties [11,13,[36][37][38][39][40][41][42]. PAP isozymes evoke depurination of genomic HIV-1 RNA [43][44][45], TMV RNA [46], poliovirus [47], herpes simplex virus (HSV) [48], influenza virus [49], and brome mosaic virus (BMV) [50], among many others, showing a broad spectrum of antiviral activity [13].…”

Expression of pokeweed antiviral proteins in creeping bentgrass

“…The amino acid sequence of PAPII is only 35% identical to that of PAP (Lin et al 1991;Poyet et al 1994). PAPII expression in transgenic tobacco also resulted in viral and fungal resistance and was less phytotoxic than expression of the native form of PAP (Wang et al 1998).…”