Do DEAD-box proteins promote group II intron splicing without unwinding RNA?

Mol Cell. 2007 Oct 12;28(1):159-66. doi: 10.1016/j.molcel.2007.07.028.


The DEAD-box protein Mss116p promotes group II intron splicing in vivo and in vitro. Here we explore two hypotheses for how Mss116p promotes group II intron splicing: by using its RNA unwinding activity to act as an RNA chaperone or by stabilizing RNA folding intermediates. We show that an Mss116p mutant in helicase motif III (SAT/AAA), which was reported to stimulate splicing without unwinding RNA, retains ATP-dependent unwinding activity and promotes unfolding of a structured RNA. Its unwinding activity increases sharply with decreasing duplex length and correlates with group II intron splicing activity in quantitative assays. Additionally, we show that Mss116p can promote ATP-independent RNA unwinding, presumably via single-strand capture, also potentially contributing to DEAD-box protein RNA chaperone activity. Our findings favor the hypothesis that DEAD-box proteins function in group II intron splicing as in other processes by using their unwinding activity to act as RNA chaperones.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • DEAD-box RNA Helicases / genetics
  • DEAD-box RNA Helicases / metabolism*
  • Introns*
  • Mutation
  • Nucleic Acid Conformation*
  • Nucleic Acid Denaturation
  • RNA / chemistry*
  • RNA / genetics
  • RNA / metabolism*
  • RNA Splicing*
  • Recombinant Fusion Proteins / genetics
  • Recombinant Fusion Proteins / metabolism
  • Saccharomyces cerevisiae Proteins / genetics
  • Saccharomyces cerevisiae Proteins / metabolism*


  • Recombinant Fusion Proteins
  • Saccharomyces cerevisiae Proteins
  • RNA
  • MSS116 protein, S cerevisiae
  • DEAD-box RNA Helicases