Crucial Roles of Two Hydrated Mg²⁺ Ions in Reaction Catalysis of the Pistol Ribozyme.

ABSTRACT: Pistol ribozymes constitute a new class of small self-cleaving RNAs. Crystal structures have been solved, providing three-dimensional snapshots along the reaction coordinate of pistol phosphodiester cleavage, corresponding to the pre-catalytic state, a vanadate mimic of the transition state, and the product. The results led to the proposed underlying chemical mechanism. Importantly, a hydrated Mg²⁺ ion remains innersphere-coordinated to N7 of G33 in all three states, and is consistent with its likely role as acid in general acid base catalysis (δ and β catalysis). Strikingly, the new structures shed light on a second hydrated Mg²⁺ ion that approaches the scissile phosphate from its binding site in the pre-cleavage state to reach out for water-mediated hydrogen bonding

SUBMITTER: Teplova M 

PROVIDER: S-EPMC7027511 | biostudies-literature | 2020 Feb

REPOSITORIES: biostudies-literature