title: K(+)-Responsive off-to-on switching of hammerhead ribozyme through dual G-quadruplex formation requiring no heating and cooling treatment.
abstract: 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'.
authors.affiliation: Institute of Advanced Energy, Kyoto University, Gokasho, Uji, Kyoto 611-0011, Japan; Graduate School of Energy Science, Kyoto University, Gokasho, Uji, Kyoto 611-0011, Japan.
authors.forename: Yudai
authors.initials: Y
authors.lastname: Yamaoki
authors.affiliation: Institute of Advanced Energy, Kyoto University, Gokasho, Uji, Kyoto 611-0011, Japan; Graduate School of Energy Science, Kyoto University, Gokasho, Uji, Kyoto 611-0011, Japan.
authors.forename: Takashi
authors.initials: T
authors.lastname: Nagata
authors.affiliation: Institute of Advanced Energy, Kyoto University, Gokasho, Uji, Kyoto 611-0011, Japan; Graduate School of Energy Science, Kyoto University, Gokasho, Uji, Kyoto 611-0011, Japan.
authors.forename: Tsukasa
authors.initials: T
authors.lastname: Mashima
authors.affiliation: Institute of Advanced Energy, Kyoto University, Gokasho, Uji, Kyoto 611-0011, Japan; Graduate School of Energy Science, Kyoto University, Gokasho, Uji, Kyoto 611-0011, Japan. Electronic address: katahira@iae.kyoto-u.ac.jp.
authors.forename: Masato
authors.initials: M
authors.lastname: Katahira
mesh_terms: D001483:Base Sequence; D002414:Cations, Monovalent / Q000378:metabolism; D003080:Cold Temperature; D054856:G-Quadruplexes; D006361:Heating; D008969:Molecular Sequence Data; D009690:Nucleic Acid Conformation; D011188:Potassium / Q000378:metabolism*; D016337:RNA, Catalytic / Q000737:chemistry / Q000378:metabolism*
chemical_list: D002414:Cations, Monovalent; D016337:RNA, Catalytic; C427204:hammerhead ribozyme; D011188:Potassium
keywords: G-quadruplex; Potassium; RNA structure; Ribozyme; Structural transition; Switching of activity