Pokeweed antiviral protein cleaves double-stranded supercoiled DNA using the same active site required to depurinate rRNA.
Ribosome-inactivating proteins (RIPs) are N-glycosylases that remove a specific adenine from the sarcin/ricin loop of the large rRNA in a manner analogous to N-glycosylases that are involved in DNA repair. Some RIPs have been reported to remove adenines from single-stranded DNA and cleave double-stranded supercoiled DNA. The molecular basis for the activity of RIPs on double-stranded DNA is not known. Pokeweed antiviral protein (PAP), a single-chain RIP from Phytolacca americana, cleaves supercoiled DNA into relaxed and linear forms. Double-stranded DNA treated with PAP contains apurinic/apyrimidinic (AP) sites due to the removal of adenine. Using an active-site mutant of PAP (PAPx) which does not depurinate rRNA, we present evidence that double-stranded DNA treated with PAPx does not contain AP sites and is not cleaved. These results demonstrate for the first time that PAP cleaves supercoiled double-stranded DNA using the same active site that is required for depurination of rRNA.
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Biotechnology Center and the Department of Plant Pathology, Foran Hall, Room 208, Cook College,Rutgers University, Dudley Road, New Brunswick, NJ 08903, USA.
Tumer
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D000998:Antiviral Agents / Q000378:metabolism*; D019757:Carbon-Oxygen Lyases; D004247:DNA / Q000378:metabolism*; D004278:DNA, Superhelical / Q000378:metabolism*; D043603:DNA-(Apurinic or Apyrimidinic Site) Lyase; D043223:Deoxyribonuclease IV (Phage T4-Induced); D009699:N-Glycosyl Hydrolases; D010940:Plant Proteins / Q000378:metabolism*; D010957:Plasmids / Q000378:metabolism; D011687:Purines / Q000378:metabolism*; D012335:RNA, Ribosomal / Q000378:metabolism*; D054789:Ribosome Inactivating Proteins, Type 1
D000998:Antiviral Agents; D004278:DNA, Superhelical; D010940:Plant Proteins; D011687:Purines; D012335:RNA, Ribosomal; D054789:Ribosome Inactivating Proteins, Type 1; D004247:DNA; D043223:Deoxyribonuclease IV (Phage T4-Induced); D009699:N-Glycosyl Hydrolases; C024275:pokeweed antiviral protein; D019757:Carbon-Oxygen Lyases; D043603:DNA-(Apurinic or Apyrimidinic Site) Lyase