title: Mitochondrial DNA D-loop as a new target of Saporin 6 nuclease activity.
abstract: The single-chain ribosome-inactivating proteins (RIPs) from plant origin, including Saporin 6 from the seeds of Saponaria officinalis, are ribotoxins known to act as N-glycosidases which depurinate the conserved alpha sarcin loop of large rRNAs. As a consequence, the eukaryotic ribosomes become inactivated, thereby arresting the protein synthesis at the elongation step. RIPs are currently under study as antiviral and antiproliferative agents. Additional in vitro activities of RIPs against either RNA or DNA have been recently described. A specific nuclease activity on plasmidic DNA was demonstrated by either purified or bacterial-recombinant molecules. We report here that human mitochondrial DNA (mtDNA) is a new specific target of Saporin 6 nuclease activity. A unique site of cleavage has been identified and mapped within the most variable part of the D-loop region of the covalently closed circular mtDNA molecule.
authors.affiliation: Department of Experimental Pathology, University of Bologna, Via San Giacomo 14, 40126 Bologna, Italy. annagcp@alma.unibo.it
authors.forename: Anna
authors.initials: A
authors.lastname: Gasperi-Campani
authors.forename: Irene
authors.initials: I
authors.lastname: Brognara
authors.forename: Daniela
authors.initials: D
authors.lastname: Baiocchi
authors.forename: Laura
authors.initials: L
authors.lastname: Roncuzzi
mesh_terms: D015139:Blotting, Southern; D004262:DNA Restriction Enzymes / Q000378:metabolism; D004272:DNA, Mitochondrial / Q000187:drug effects* / Q000378:metabolism; D006801:Humans; D000922:Immunotoxins / Q000633:toxicity*; D009699:N-Glycosyl Hydrolases / Q000633:toxicity*; D010940:Plant Proteins / Q000633:toxicity*; D015183:Restriction Mapping; D054789:Ribosome Inactivating Proteins, Type 1; D000076985:Saporins
chemical_list: D004272:DNA, Mitochondrial; D000922:Immunotoxins; D010940:Plant Proteins; D054789:Ribosome Inactivating Proteins, Type 1; D004262:DNA Restriction Enzymes; D009699:N-Glycosyl Hydrolases; D000076985:Saporins