title: The structural basis of ribozyme-catalyzed RNA assembly.
abstract: Life originated, according to the RNA World hypothesis, from self-replicating ribozymes that catalyzed ligation of RNA fragments. We have solved the 2.6 angstrom crystal structure of a ligase ribozyme that catalyzes regiospecific formation of a 5' to 3' phosphodiester bond between the 5'-triphosphate and the 3'-hydroxyl termini of two RNA fragments. Invariant residues form tertiary contacts that stabilize a flexible stem of the ribozyme at the ligation site, where an essential magnesium ion coordinates three phosphates. The structure of the active site permits us to suggest how transition-state stabilization and a general base may catalyze the ligation reaction required for prebiotic RNA assembly.
authors.affiliation: Center for the Molecular Biology of RNA and Department of Chemistry and Biochemistry, Robert L. Sinsheimer Laboratories, University of California, Santa Cruz, Santa Cruz, CA 95064, USA.
authors.forename: Michael P
authors.initials: MP
authors.lastname: Robertson
authors.forename: William G
authors.initials: WG
authors.lastname: Scott
mesh_terms: D020029:Base Pairing; D001665:Binding Sites; D002384:Catalysis; D020134:Catalytic Domain; D003460:Crystallization; D018360:Crystallography, X-Ray; D019020:Directed Molecular Evolution; D006860:Hydrogen Bonding; D008958:Models, Molecular; D008968:Molecular Conformation; D009690:Nucleic Acid Conformation; D009843:Oligoribonucleotides / Q000737:chemistry / Q000378:metabolism; D016337:RNA, Catalytic / Q000737:chemistry* / Q000378:metabolism; D012265:Ribonucleotides / Q000737:chemistry / Q000378:metabolism; D013698:Templates, Genetic
chemical_list: D009843:Oligoribonucleotides; D016337:RNA, Catalytic; D012265:Ribonucleotides