title: Conformation and the sodium ion condensation on DNA and RNA structures in the presence of a neutral cosolute as a mimic of the intracellular media.
abstract: Water-soluble neutral cosolutes can be used to quantify biomolecular properties in the particular molecular environment occurring in a cell. We studied the conformation and the thermal stability of DNA and RNA structures in the presence of PEG [poly(ethylene glycol)] and smaller cosolutes of glycerol, ethylene glycol, 1,3-propanediol, 2-methoxyethanol, and 1,2-dimethoxyethane. Although the neutral cosolutes destabilized the oligonucleotide duplex and the hairpin structures, the left-handed Z-form duplex was more energetically favored in the cosolute-containing solutions. These observations were due to the contribution of water molecule on the nucleotide structure formations because the cosolutes act as an osmolyte to reduce the water activity of a solution. Moreover, the sodium ion condensation for the duplex and the hairpin formations was reduced in the presence of PEG, while that for the transition from the B-form to the Z-form was unaltered. The CD (circular dichroism) and EPR (electron paramagnetic resonance) spectra demonstrated that the cosolutes changed the helical conformation of the unstructured oligonucleotides, but not those of the ordered structures. The results of the favorable formation of the noncanonical nucleotide structures, and minimized conformational and thermal perturbations of the ordered nucleotide structures in the cosolute-containing solutions implicate the significance of the intracellular environment on DNA and RNA structures in a cell.
authors.affiliation: Frontier Institute for Biomolecular Engineering Research (FIBER), Konan University, 8-9-1 Okamoto, Higashinada-Ku, Kobe 658-8501, Japan. shuichi@center.konan-u.ac.jp
authors.forename: Shu-Ichi
authors.initials: S
authors.lastname: Nakano
authors.forename: Lei
authors.initials: L
authors.lastname: Wu
authors.forename: Hirohito
authors.initials: H
authors.lastname: Oka
authors.forename: Hisae Tateishi
authors.initials: HT
authors.lastname: Karimata
authors.forename: Toshimasa
authors.initials: T
authors.lastname: Kirihata
authors.forename: Yuichi
authors.initials: Y
authors.lastname: Sato
authors.forename: Satoshi
authors.initials: S
authors.lastname: Fujii
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Sakai
authors.forename: Masayasu
authors.initials: M
authors.lastname: Kuwahara
authors.forename: Masayuki
authors.initials: M
authors.lastname: Kuwahara
authors.forename: Hiroaki
authors.initials: H
authors.lastname: Sawai
authors.forename: Naoki
authors.initials: N
authors.lastname: Sugimoto
mesh_terms: D004247:DNA / Q000737:chemistry*; D004578:Electron Spin Resonance Spectroscopy / Q000379:methods; D005019:Ethyl Ethers / Q000737:chemistry; D019855:Ethylene Glycol / Q000737:chemistry; D005026:Ethylene Glycols / Q000737:chemistry; D005990:Glycerol / Q000737:chemistry; D042541:Intracellular Space / Q000737:chemistry*; D007477:Ions / Q000737:chemistry; D009690:Nucleic Acid Conformation; D009841:Oligonucleotides / Q000737:chemistry; D011092:Polyethylene Glycols / Q000737:chemistry*; D011409:Propylene Glycols / Q000737:chemistry; D012313:RNA / Q000737:chemistry*; D012964:Sodium / Q000737:chemistry*; D012996:Solutions / Q000737:chemistry; D013696:Temperature
chemical_list: D005019:Ethyl Ethers; D005026:Ethylene Glycols; D007477:Ions; D009841:Oligonucleotides; D011409:Propylene Glycols; D012996:Solutions; D011092:Polyethylene Glycols; C041787:1,3-propanediol; D012313:RNA; D004247:DNA; D012964:Sodium; C005219:methyl cellosolve; D019855:Ethylene Glycol; C024683:1,2-dimethoxyethane; D005990:Glycerol