Ribosome-inactivating proteins in edible plants and purification and characterization of a new ribosome-inactivating protein from Cucurbita moschata

• Published in: Biochimica et biophysica acta Vol. 1760; no. 5; pp. 783 - 792
• Main Authors: Barbieri, Luigi, Polito, Letizia, Bolognesi, Andrea, Ciani, Marialibera, Pelosi, Emanuele, Farini, Valentina, Jha, Ajay K., Sharma, Neelam, Vivanco, Jorge M., Chambery, Angela, Parente, Augusto, Stirpe, Fiorenzo
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier B.V 01.05.2006
• Subjects: Amino Acid Sequence; Animals; Anti-Bacterial Agents - immunology; Anti-Bacterial Agents - isolation & purification; Anti-Bacterial Agents - pharmacology; Antifungal Agents - immunology; Antifungal Agents - isolation & purification; Antifungal Agents - pharmacology; Cell Extracts - chemistry; Cell Extracts - pharmacology; Cross Reactions; Cucurbita - metabolism; Cucurbita moschata; DNA - drug effects; DNA glycosylase; Glycoproteins - immunology; Glycoproteins - isolation & purification; Glycoproteins - pharmacology; Humans; Inhibitory Concentration 50; Lycopersicon esculentum - metabolism; Molecular Sequence Data; Plant defence; Plant Proteins - immunology; Plant Proteins - isolation & purification; Plant Proteins - pharmacology; Protein Biosynthesis - drug effects; Pumpkin; Rabbits; Ribosome Inactivating Proteins, Type 1; Ribosome-inactivating protein; Ribosomes - drug effects; RNA, Ribosomal - drug effects; Tomato; DNA glycosylase; Ribosome-inactivating protein; Plant defence; Tomato; Pumpkin; Cucurbita moschata
• ISSN: 0304-4165; 0006-3002; 1872-8006
• DOI: 10.1016/j.bbagen.2006.01.002

The basic protein fraction of tissue extracts from 40 edible plants inhibited cell-free protein synthesis and released adenine from herring sperm DNA, thus having adenine glycosylase activity. This suggested the presence of ribosome-inactivating proteins (RIPs) in the plant extracts. This indication was further strengthened by the presence of the two activities after a partial chromatographic purification of three extracts, including that from Lycopersicon esculentum (tomato), which had very low activity. From the extract of Cucurbita moschata (pumpkin), the most active one, a glycoprotein of 30,665 Da was purified which had the properties of a RIP, in that (i) it inhibited protein synthesis by a rabbit reticulocyte lysate with IC 50 (concentration giving 50% inhibition) 0.035 nM (1.08 ng ml −1) and by HeLa, HT29 and JM cells with IC 50 in the 100 nM range, (ii) deadenylated hsDNA and other polynucleotidic substrates, and (iii) depurinated yeast rRNA at a concentration of 0.1 ng ml −1, all values being comparable to those of other RIPs. The C. moschata RIP gave a weak cross-reaction only with an antiserum against dianthin 32, but not with antisera against other RIPs, and had superoxide dismutase, antifungal and antibacterial activities.