Interactions between saporin, a ribosome-inactivating protein, and DNA: a study by atomic force microscopy.
Saporins are enzymes belonging to the PNAG class (polynucleotide: adenosine glycosidase), plant enzymes commonly known as ribosome-inactivating proteins (RIP), as a result of their property of irreversibly damaging eukaryotic ribosomes. Direct imaging with tapping-mode atomic force microscopy (AFM) has been used to study pGEM-4Z plasmid DNA binding to the saporin-SO6 (isoform from Saponaria officinalis seeds). Saporin wrapped the plasmidic DNA, and distribution of the enzyme molecules along the DNA chain was markedly variable; plasmid digested with saporin-SO6 appeared fragmented or topologically modified. The supercoiled DNA strands were cleaved, giving rise to a linearized form and to relaxed forms. Electrophoretic analysis of the effect of standard preparations of saporin-SO6 on pGEM-4S confirmed the presence of DNA strand-cleaving activity.
Poma
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Department of Basic and Applied Biology, University of L'Aquila, Via Vetoio, Coppito, L'Aquila, Italy.
Spanò
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Pittaluga
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E
Tucci
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Palladino
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L
Limongi
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T
D004247:DNA / Q000378:metabolism* / Q000648:ultrastructure*; D000922:Immunotoxins / Q000378:metabolism* / Q000648:ultrastructure*; D018625:Microscopy, Atomic Force; D009699:N-Glycosyl Hydrolases / Q000378:metabolism* / Q000648:ultrastructure*; D010940:Plant Proteins / Q000378:metabolism* / Q000648:ultrastructure*; D010957:Plasmids / Q000378:metabolism / Q000648:ultrastructure; D054789:Ribosome Inactivating Proteins, Type 1; D012270:Ribosomes / Q000502:physiology; D000076985:Saporins
D000922:Immunotoxins; D010940:Plant Proteins; D054789:Ribosome Inactivating Proteins, Type 1; D004247:DNA; D009699:N-Glycosyl Hydrolases; D000076985:Saporins