title: Conformational change of single-stranded RNAs induced by liposome binding.
abstract: The interaction between single-stranded RNAs and liposomes was studied using UV, Fourier Transform Infrared spectroscopy (FTIR) and Circular Dichroism spectroscopy (CD). The effect of the surface characteristics of liposomes, which were composed of 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC) and modified with cholesterol (Ch) or 1,2-dioleoyl-3-trimethylammonium propane (DOTAP), on the liposome-RNA interaction was investigated. The fluorescence of 6-(p-toluidino)naphthalene-2-sulfonate (TNS) embedded in the liposome surface (ε = 30-40) was decreased in the presence of tRNA, suggesting that single-stranded tRNA could bind onto the liposome. The dehydration of -PO₂⁻-, guanine (G) and cytosine (C) of tRNA molecules in the presence of liposomes suggested both an electrostatic interaction (phosphate backbone of tRNA and trimethylammonium group of POPC, DOTAP) and a hydrophobic interaction (guanine or cytosine of tRNA and aliphatic tail of lipid). The tRNA conformation on the liposome was determined by CD spectroscopy. POPC/Ch (70/30) maintained tRNA conformation without any denaturation, while POPC/DOTAP(70/30) drastically denatured it. The mRNA translation was evaluated in an Escherichia coli cell-free translation system. POPC/Ch(70/30) enhanced expression of green fluorescent protein (GFP) (116%) while POPC/DOTAP(70/30) inhibited (37%), suggesting that the conformation of RNAs was closely related to the translation efficiency. Therefore, single-stranded RNAs could bind to liposomal membranes through electrostatic and hydrophobic attraction, after which conformational changes were induced depending on the liposome characteristics.
authors.affiliation: Division of Chemical Engineering, Graduate School of Engineering Science, Osaka University, Toyonaka, Osaka 560-8531, Japan.
authors.forename: Keishi
authors.initials: K
authors.lastname: Suga
authors.forename: Tomoyuki
authors.initials: T
authors.lastname: Tanabe
authors.forename: Hibiki
authors.initials: H
authors.lastname: Tomita
authors.forename: Toshinori
authors.initials: T
authors.lastname: Shimanouchi
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Umakoshi
mesh_terms: D002942:Circular Dichroism; D057927:Hydrophobic and Hydrophilic Interactions; D008081:Liposomes / Q000737:chemistry*; D009690:Nucleic Acid Conformation; D014176:Protein Biosynthesis; D012333:RNA, Messenger / Q000737:chemistry*; D012343:RNA, Transfer / Q000737:chemistry*; D017550:Spectroscopy, Fourier Transform Infrared; D055672:Static Electricity
chemical_list: D008081:Liposomes; D012333:RNA, Messenger; D012343:RNA, Transfer