title: Structural study of an RNA aptamer for a Tat protein complexed with ligands.
abstract: An RNA aptamer for an HIV Tat protein has been isolated by the in vitro SELEX method. The RNA aptamer binds to the Tat protein 50-100 times more strongly than native TAR RNA does. Here, we have investigated the structure of the RNA aptamer complexed with ligands, partial peptide fragments of the Tat protein or argininamide, by multidimensional 1H/13C/15N NMR. It is strongly suggested that two U:A:U base triples are formed in the RNA aptamer upon binding of ligands. Specific hydrogen bonds between arginine side chains of ligands and guanine bases located adjacent to the base triples are identified. On the basis of many intramolecular and intermolecular NOEs, a structural model of the complex has been constructed.
authors.affiliation: Department of Chemistry and Biotechnology, Faculty of Engineering, Yokohama National University, Japan.
authors.forename: M
authors.initials: M
authors.lastname: Katahira
authors.forename: S
authors.initials: S
authors.lastname: Kobayashi
authors.forename: A
authors.initials: A
authors.lastname: Matsugami
authors.forename: K
authors.initials: K
authors.lastname: Ouhashi
authors.forename: S
authors.initials: S
authors.lastname: Uesugi
authors.forename: R
authors.initials: R
authors.lastname: Yamamoto
authors.forename: K
authors.initials: K
authors.lastname: Taira
authors.forename: S
authors.initials: S
authors.lastname: Nishikawa
authors.forename: P
authors.initials: P
authors.lastname: Kumar
mesh_terms: D001483:Base Sequence; D002247:Carbon Isotopes; D015696:Gene Products, tat / Q000737:chemistry* / Q000378:metabolism*; D008958:Models, Molecular; D009587:Nitrogen Isotopes; D019906:Nuclear Magnetic Resonance, Biomolecular; D009690:Nucleic Acid Conformation; D009843:Oligoribonucleotides / Q000138:chemical synthesis / Q000737:chemistry*; D012313:RNA / Q000737:chemistry* / Q000378:metabolism*
chemical_list: D002247:Carbon Isotopes; D015696:Gene Products, tat; D009587:Nitrogen Isotopes; D009843:Oligoribonucleotides; D012313:RNA