Circularization of linear viroid RNA via 2'-phosphomonoester, 3', 5'-phosphodiester bonds by a novel type of RNA ligase from wheat germ and Chlamydomonas.
A novel type of RNA ligase activity in extracts of wheat germ or Chlamydomonas requires 2', 3'-cyclic phosphate and 5'-phosphate ends for ligation to form a 2'-phosphomonoester, 3',5'-phosphodiester bond. Using 5'-3 2P-labeled linear PSTV, we demonstrate that RNase T1-nicked viroid predominantly forms (formula; see text) U-bonds. Natural linear PSTV, however, forms mainly (formula; see text) A-bonds upon enzymatic circularization. We show that natural linear PSTV RNA has nicks between C181 and A182, or between C348 and A349, and that consequently C181 and C348 carry 2',3'-cyclophosphate termini.
D055598:Chemical Phenomena; D002621:Chemistry; D002696:Chlamydomonas / Q000201:enzymology*; D010761:Phosphorus Radioisotopes; D010944:Plants / Q000201:enzymology*; D011118:Polynucleotide Ligases / Q000378:metabolism*; D011130:RNA Ligase (ATP) / Q000378:metabolism*; D012367:RNA, Viral; D011865:Radioisotope Dilution Technique; D014908:Triticum / Q000201:enzymology; D014772:Viroids / Q000032:analysis*
D010761:Phosphorus Radioisotopes; D012367:RNA, Viral; D011118:Polynucleotide Ligases; D011130:RNA Ligase (ATP)