PMID: 25038788
Liu Y, Wilson TJ, McPhee SA, Lilley DM
Crystal structure and mechanistic investigation of the twister ribozyme.
Nat Chem Biol. 2014 Sep;10(9):739-44. doi: 10.1038/nchembio.1587. Epub 2014 Jul, 20.
We present a crystal structure at 2.3-A resolution of the recently described nucleolytic ribozyme twister. The RNA adopts a previously uncharacterized compact fold based on a double-pseudoknot structure, with the active site at its center. Eight highly conserved nucleobases stabilize the core of the ribozyme through the formation of one Watson-Crick and three noncanonical base pairs, and the highly conserved adenine 3' of the scissile phosphate is bound in the major groove of an adjacent pseudoknot. A strongly conserved guanine nucleobase directs its Watson-Crick edge toward the scissile phosphate in the crystal structure, and mechanistic evidence supports a role for this guanine as either a general base or acid in a concerted, general acid-base-catalyzed cleavage reaction.