Single-molecule analysis of Mss116-mediated group II intron folding

Nature. 2010 Oct 21;467(7318):935-9. doi: 10.1038/nature09422. Epub 2010 Oct 13.


DEAD-box helicases are conserved enzymes involved in nearly all aspects of RNA metabolism, but their mechanisms of action remain unclear. Here, we investigated the mechanism of the DEAD-box protein Mss116 on its natural substrate, the group II intron ai5γ. Group II introns are structurally complex catalytic RNAs considered evolutionarily related to the eukaryotic spliceosome, and an interesting paradigm for large RNA folding. We used single-molecule fluorescence to monitor the effect of Mss116 on folding dynamics of a minimal active construct, ai5γ-D135. The data show that Mss116 stimulates dynamic sampling between states along the folding pathway, an effect previously observed only with high Mg(2+) concentrations. Furthermore, the data indicate that Mss116 promotes folding through discrete ATP-independent and ATP-dependent steps. We propose that Mss116 stimulates group II intron folding through a multi-step process that involves electrostatic stabilization of early intermediates and ATP hydrolysis during the final stages of native state assembly.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Adenosine Triphosphate / metabolism
  • DEAD-box RNA Helicases / metabolism*
  • Fluorescence
  • Fluorescence Resonance Energy Transfer
  • Hydrolysis
  • Introns / genetics*
  • Nucleic Acid Conformation*
  • RNA, Catalytic / chemistry
  • RNA, Catalytic / metabolism
  • Saccharomyces cerevisiae / enzymology
  • Saccharomyces cerevisiae / genetics
  • Saccharomyces cerevisiae Proteins / metabolism*
  • Salinity
  • Static Electricity
  • Thermodynamics


  • RNA, Catalytic
  • Saccharomyces cerevisiae Proteins
  • Adenosine Triphosphate
  • MSS116 protein, S cerevisiae
  • DEAD-box RNA Helicases