K(+)-Responsive off-to-on switching of hammerhead ribozyme through dual G-quadruplex formation requiring no heating and cooling treatment

Biochem Biophys Res Commun. 2015 Dec 4-11;468(1-2):27-31. doi: 10.1016/j.bbrc.2015.10.173. Epub 2015 Nov 10.


Functional RNAs that switch their activities in response to K(+) may sense the intracellular (100 mM) and extracellular (5 mM) K(+) concentrations and regulate their functions accordingly. Previously, we developed a quadruplex hammerhead ribozyme (QHR) whose conformational change, from a duplex to a G-quadruplex, triggered by K(+) results in expression of the activity. However, this QHR required heating and cooling treatment (annealing) to induce the K(+)-responsive conformational change and activity. Here, we developed a new quadruplex hammerhead ribozyme (QHR) system that does not require annealing to induce the K(+)-responsive conformational change and activity. This system is composed of QHR and a G-quadruplex-forming complementary DNA strand (QCS). In the absence of K(+), QCS formed a duplex with QHR, which suppressed the residual activity. Upon elevation of the K(+) concentration, QCS dissociated from QHR was trapped in a G-quadruplex, and then QHR could form a G-quadruplex and exerted the activity. The 11.6-fold higher activity was induced by K(+) with an EC50 value of 23 mM, but not by Na(+), which is desirable when the activity switching between the intra-/extracellular environment is aimed at. This is the first report of the activation of functional RNA through a 'dual G-quadruplex formation system'.

Keywords: G-quadruplex; Potassium; RNA structure; Ribozyme; Structural transition; Switching of activity.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Base Sequence
  • Cations, Monovalent / metabolism
  • Cold Temperature
  • G-Quadruplexes*
  • Heating
  • Molecular Sequence Data
  • Nucleic Acid Conformation
  • Potassium / metabolism*
  • RNA, Catalytic / chemistry
  • RNA, Catalytic / metabolism*


  • Cations, Monovalent
  • RNA, Catalytic
  • hammerhead ribozyme
  • Potassium