Ribozyme cleavage of a 2,5-phosphodiester linkage: mechanism and a restricted divalent metal-ion requirement.

Journal Article

The natural substrate cleaved by the hepatitis delta virus (HDV) ribozyme contains a 3',5'-phosphodiester linkage at the cleavage site; however, a 2',5'-linked ribose-phosphate backbone can also be cleaved by both trans-acting and self-cleaving forms of the HDV ribozyme. With substrates containing either linkage, the HDV ribozyme generated 2',3'-cyclic phosphate and 5'-hydroxyl groups suggesting that the mechanisms of cleavage in both cases were by a nucleophilic attack on the phosphorus center by the adjacent hydroxyl group. Divalent metal ion was required for cleavage of either linkage. However, although the 3',5'-linkage was cleaved slightly faster in Ca2+ than in Mg2+, the 2',5'-linkage was cleaved in Mg2+ (or Mn2+) but not Ca2+. This dramatic difference in metal-ion specificity is strongly suggestive of a crucial metal-ion interaction at the active site. In contrast to the HDV ribozymes, cleavage at a 2',5'-phosphodiester bond was not efficiently catalyzed by the hammerhead ribozyme. The relaxed linkage specificity of the HDV ribozymes may be due in part to lack of a rigid binding site for sequences 5' to the cleavage site.

Full Text

Duke Authors

Cited Authors

  • Shih, IH; Been, MD

Published Date

  • September 1999

Published In

Volume / Issue

  • 5 / 9

Start / End Page

  • 1140 - 1148

PubMed ID

  • 10496215

International Standard Serial Number (ISSN)

  • 1355-8382

Language

  • eng

Conference Location

  • United States