Isolation and partial characterization of a new ribosome-inactivating protein from Petrocoptis glaucifolia (Lag.) Boiss

• Published in: Planta Vol. 186; no. 4; pp. 532 - 540
• Main Authors: Arias, F.J, Rojo, M.A, Ferreras, J.M, Iglesias, R, Munoz, R, Rocher, A, Mendez, E, Barbieri, L, Girbes, T
• Format: Journal Article
• Language: English
• Published: Germany 01.03.1992
• Subjects: amino acid sequences; Caryophyllaceae; Cucumis sativus; enzyme activity; inhibitors; molecular sequence data; petrocoptis glaucifolia subsp. viscosa; petroglaucin; protein composition; protein content; protein synthesis; purification; ribosomes; saporins; translation; Triticum aestivum; Vicia; vicia lens; Vicia sativa; Spain
• ISSN: 0032-0935; 1432-2048
• DOI: 10.1007/BF00198033

Petrocoptis glaucifolia, a paleoendemic member of the Caryophyllaceae from the North of Spain, was found to contain at least five proteins that inhibit protein synthesis in a rabbit reticulocyte lysate. One of them, for which the name petroglaucin is proposed, was purified to apparent electrophoretic homogeneity by chromatography through S-Sepharose Fast Flow, Sephadex G-75 and CM-Sepharose Fast Flow. The apparent Mr of the preparation was 27 500. This protein does not contain appreciable glycan chains and displays 45.8% of NH2-terminal amino-acid sequence homology with some ribosome-inactivating proteins from Saponaria officinalis, another member of the Caryophyllaceae. Petroglaucin shows the following functional properties: (i) it strongly inhibits the rabbit-reticulocyte-lysate system and Vicia sativa cell-free extracts, both coded by endogenous messengers, and also inhibits poly(U)-directed polyphenylalanine synthesis by Vicia saliva cell-free extracts and purified rat-liver ribosomes; (ii) it shows much less inhibitory capacity in wheat-germ. Cucumis sativus and rat-liver cell-free systems coded by endogenous messengers; (iii) the inhibitory effects on purified rat-liver ribosomes were irreversible; (vi) it promotes the release of adenine from purified rat-liver ribosomes. The total activity of this translational inhibitor has been found to increase up to 11-fold during its purification, indicating that some regulatory factor that normally blocks the translational inhibitory activity of the ribosome-inactivating protein in crude extracts of the plant is removed during purification.