Structural requirement for Mg2+ binding in the group I intron core

Prashanth Rangan, Sarah A. Woodson

Research output: Contribution to journalArticlepeer-review


Divalent metal ions are required for splicing of group I introns, but their role in maintaining the structure of the active site is still under investigation. Ribonuclease and hydroxyl radical footprinting of a small group I intron from Azoarcus pre-tRNAIle showed that tertiary interactions between helical domains are stable in a variety of cations. Only Mg2+, however, induced a conformational change in the intron core that correlates with self-splicing activity. Three metal ion binding sites in the catalytic core were identified by Tb(III)-dependent cleavage. Two of these are near bound substrates in a three-dimensional model of the ribozyme. A third metal ion site is near an A minor motif in P3. In the pre-tRNA, Tb3+ cleavage was redirected to the 5′ and 3′ splice sites, consistent with metal-dependent activation of splice site phosphodiesters. The results show that many counterions induce global folding, but organization of the group I active site is specifically linked to Mg2+ binding at a few sites.

Original languageEnglish (US)
Pages (from-to)229-238
Number of pages10
JournalJournal of molecular biology
Issue number2
StatePublished - May 30 2003
Externally publishedYes


  • Equilibrium phase diagram
  • Group I ribozyme
  • Metal ions
  • RNA folding
  • RNA stability

ASJC Scopus subject areas

  • Structural Biology
  • Molecular Biology


Dive into the research topics of 'Structural requirement for Mg<sup>2+</sup> binding in the group I intron core'. Together they form a unique fingerprint.

Cite this