The structure of a nucleolytic ribozyme that employs a catalytic metal ion.

ABSTRACT: 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 pK_a, consistent with proton transfer in the transiti

SUBMITTER: Liu Y 

PROVIDER: S-EPMC5392355 | biostudies-literature | 2017 May

REPOSITORIES: biostudies-literature