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

Yamaoki, Yudai  ,  Nagata, Takashi  ,  Mashima, Tsukasa  ,  Katahira, Masato

468 ( 1-2 )  , pp.27 - 31 , 2015-12-04 , Elsevier Inc.
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'.

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