title: Structure model and physicochemical properties of the C-U mismatch pair in the double stranded RNA in solution.
abstract: Structure of the C-U mismatch pair was reported only in crystal but none in solution. Here we have studied the structure and physicochemical properties of the C-U mismatch pair in a double stranded RNA in solution. RNA oligomers r(CGACUCAGG) and r(CCUGCGUCG) form a double stranded structure with the C-U pair. The arrangement of the C-U pair derived from the model building based on nOe gives a similar structural feature to that in crystal. The modeling reveals that the amino-proton of cytidine and the keto-oxygen of uridine are located within hydrogen bonding distance, and the imino proton of uridine is exposed to bulk water. From the melting experiment which monitors chemical shifts of non-exchangeable protons, the melting of all the base-pairs including the C-U pair occurs simultaneously. This suggests the possibility where the C-U mismatch pair is stacked on the neighboring base-pairs in the double helix until the duplex is denatured to single strands.
authors.affiliation: Institute for Protein Research, Osaka University, Japan.
authors.forename: Y
authors.initials: Y
authors.lastname: Tanaka
authors.forename: C
authors.initials: C
authors.lastname: Kojima
authors.forename: T
authors.initials: T
authors.lastname: Yamazaki
authors.forename: Y
authors.initials: Y
authors.lastname: Kyogoku
authors.forename: S
authors.initials: S
authors.lastname: Miyashita
authors.forename: A
authors.initials: A
authors.lastname: Ono
authors.forename: M
authors.initials: M
authors.lastname: Kainosho
mesh_terms: D001482:Base Composition; D001483:Base Sequence; D003596:Cytosine; D019906:Nuclear Magnetic Resonance, Biomolecular; D009690:Nucleic Acid Conformation; D009691:Nucleic Acid Denaturation; D009843:Oligoribonucleotides / Q000737:chemistry*; D012330:RNA, Double-Stranded / Q000737:chemistry*; D012996:Solutions; D014498:Uracil
chemical_list: D009843:Oligoribonucleotides; D012330:RNA, Double-Stranded; D012996:Solutions; D014498:Uracil; D003596:Cytosine