5t5a

Publication Abstract from PubMed

The TS ribozyme (originally called "twister sister") is a catalytic RNA. We present a crystal structure of the ribozyme in a pre-reactive conformation. Two co-axial helical stacks are organized by a three-way junction and two tertiary contacts. Five divalent metal ions are directly coordinated to RNA ligands, making important contributions to the RNA architecture. The scissile phosphate lies in a quasihelical loop region that is organized by a network of hydrogen bonding. A divalent metal ion is directly bound to the nucleobase 5' to the scissile phosphate, with an inner-sphere water molecule positioned to interact with the O2' nucleophile. The rate of ribozyme cleavage correlated in a log-linear manner with divalent metal ion pKa, consistent with proton transfer in the transition state, and we propose that the bound metal ion is a likely general base for the cleavage reaction. Our data indicate that the TS ribozyme functions predominantly as a metalloenzyme.

The structure of a nucleolytic ribozyme that employs a catalytic metal ion.,Liu Y, Wilson TJ, Lilley DM Nat Chem Biol. 2017 Mar 6. doi: 10.1038/nchembio.2333. PMID:28263963^[1]

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.