The enzymatic conversion of 3'-phosphate terminated RNA chains to 2',3'-cyclic phosphate derivatives

J Biol Chem. 1985 May 25;260(10):6088-97.


The enzyme, RNA cyclase, has been purified from cell-free extracts of HeLa cells approximately 6000-fold. The enzyme catalyzes the conversion of 3'-phosphate ends of RNA chains to the 2',3'-cyclic phosphate derivative in the presence of ATP or adenosine 5'-(gamma-thio)triphosphate (ATP gamma S) and Mg2+. The formation of 1 mol of 2',3'-cyclic phosphate ends is associated with the disappearance of 1 mol of 3'-phosphate termini and the hydrolysis of 1 mol of ATP gamma S to AMP and thiopyrophosphate. No other nucleotides could substitute for ATP or ATP gamma S in the reaction. The reaction catalyzed by RNA cyclase was not reversible and exchange reactions between [32P]pyrophosphate and ATP were not detected. However, an enzyme-AMP intermediate could be identified that was hydrolyzed by the addition of inorganic pyrophosphate or 3'-phosphate terminated RNA chains but not by 3'-OH terminated chains or inorganic phosphate. 3'-[32P](Up)10Gp* could be converted to a form that yielded, (Formula: see text) after degradation with nuclease P1, by the addition of wheat germ RNA ligase, 5'-hydroxylpolynucleotide kinase, RNA cyclase, and ATP. This indicates that the RNA cyclase had catalyzed the formation of the 2',3'-cyclic phosphate derivative, the kinase had phosphorylated the 5'-hydroxyl end of the RNA, and the wheat germ RNA ligase had catalyzed the formation of a 3',5'-phosphodiester linkage concomitant with the conversion of the 2',3'-cyclic end to a 2'-phosphate terminated residue.

Publication types

  • Comparative Study
  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Adenosine Triphosphate / pharmacology
  • HeLa Cells / metabolism
  • Humans
  • Ligases / isolation & purification
  • Ligases / metabolism*
  • Nucleic Acid Precursors / metabolism
  • RNA / biosynthesis*
  • RNA / metabolism
  • RNA Ligase (ATP) / metabolism
  • RNA Splicing*
  • RNA, Circular
  • Triticum / metabolism


  • Nucleic Acid Precursors
  • RNA, Circular
  • RNA
  • Adenosine Triphosphate
  • Ligases
  • RNA 3'-terminal phosphate cyclase
  • RNA Ligase (ATP)