title: The catalytic mechanism of hairpin ribozyme studied by hydrostatic pressure.
abstract: The discovery of ribozymes strengthened the RNA world hypothesis, which assumes that these precursors of modern life both stored information and acted as catalysts. For the first time among extensive studies on ribozymes, we have investigated the influence of hydrostatic pressure on the hairpin ribozyme catalytic activity. High pressures are of interest when studying life under extreme conditions and may help to understand the behavior of macromolecules at the origins of life. Kinetic studies of the hairpin ribozyme self-cleavage were performed under high hydrostatic pressure. The activation volume of the reaction (34 +/- 5 ml/mol) calculated from these experiments is of the same order of magnitude as those of common protein enzymes, and reflects an important compaction of the RNA molecule during catalysis, associated to a water release. Kinetic studies were also carried out under osmotic pressure and confirmed this interpretation and the involvement of water movements (78 +/- 4 water molecules per RNA molecule). Taken together, these results are consistent with structural studies indicating that loops A and B of the ribozyme come into close contact during the formation of the transition state. While validating baro-biochemistry as an efficient tool for investigating dynamics at work during RNA catalysis, these results provide a complementary view of ribozyme catalytic mechanisms.
authors.affiliation: Institut Jacques-Monod, Laboratoire de Biochimie de l'Evolution et Adaptabilité Moléculaire Université Paris VI, Tour 43, 2 place Jussieu, 75251 Paris Cedex 05, France.
authors.forename: Sylvia
authors.initials: S
authors.lastname: Tobé
authors.forename: Thomas
authors.initials: T
authors.lastname: Heams
authors.forename: Jacques
authors.initials: J
authors.lastname: Vergne
authors.forename: Guy
authors.initials: G
authors.lastname: Hervé
authors.forename: Marie-Christine
authors.initials: MC
authors.lastname: Maurel
mesh_terms: D001483:Base Sequence; D002384:Catalysis; D006874:Hydrostatic Pressure; D007700:Kinetics; D008969:Molecular Sequence Data; D009997:Osmotic Pressure; D016337:RNA, Catalytic / Q000737:chemistry / Q000378:metabolism*; D012997:Solvents / Q000737:chemistry
chemical_list: D016337:RNA, Catalytic; D012997:Solvents; C418481:hairpin ribozyme