title: Molecular crowding effect on metal ion binding properties of the hammerhead ribozyme.
abstract: Although metal ion is essential for the DNA and RNA folding, there are a limited number of reports describing the influence of molecular environments on the metal ion binding. Here, we investigated the binding properties of Mg(2+) and Na(+) toward the hammerhead ribozyme in the presence of PEG [poly(ethylene glycol)] as a cosolute that changes the solvent property of the reaction. PEG8000 (PEG with the average molecular weight of 8000) increased the reaction rate at lower Mg(2+) concentrations but not at higher concentrations. We also found that PEG8000 unchanged the number of Mg(2+) bound while the binding cooperativity of Na(+) in the reaction without divalent metal ion was altered. The change of Na(+) condensation by cosolute has also been reported for diffusely bound Na(+) to Watson-Crick base pairs. It is thus supposed that diffusely bound Na(+) stabilizes the ribozyme active form in the absence of divalent metal ion. This study provides insights into the RNA-metal ion interaction and the hammerhead ribozyme activity under the molecular crowding condition occurred in a cell and on biosensor devices.
authors.affiliation: Frontier Institute for Biomolecular Engineering Research (FIBER), Konan University, Higashinada-ku, Kobe 658-8501, Japan.
authors.forename: Shu-ichi
authors.initials: S
authors.lastname: Nakano
authors.forename: Yuichi
authors.initials: Y
authors.lastname: Kitagawa
authors.forename: Hisae Tateishi
authors.initials: HT
authors.lastname: Karimata
authors.forename: Naoki
authors.initials: N
authors.lastname: Sugimoto
mesh_terms: D002412:Cations / Q000737:chemistry; D008274:Magnesium / Q000737:chemistry*; D011092:Polyethylene Glycols / Q000737:chemistry; D016337:RNA, Catalytic / Q000737:chemistry*; D012964:Sodium / Q000737:chemistry*; D012997:Solvents / Q000737:chemistry
chemical_list: D002412:Cations; D016337:RNA, Catalytic; D012997:Solvents; C427204:hammerhead ribozyme; D011092:Polyethylene Glycols; D012964:Sodium; D008274:Magnesium