Transitions Between the Steps of Forward and Reverse Splicing of Group IIC introns.

Transitions Between the Steps of Forward and Reverse Splicing of Group IIC introns.
RNA. 2020 Mar 03;:
Authors: Smathers CM, Robart AR
Abstract
Group II introns are mobile genetic elements that perform both self-splicing and intron mobility reactions. These ribozymes are comprised of a catalytic RNA core that binds to an intron-encoded protein (IEP) to form a ribonucleoprotein (RNP) complex. Splicing proceeds through two competing reactions: hydrolysis or branching. Group IIC intron ribozymes have a minimal RNA architecture, and splice almost exclusively through hydrolysis in ribozyme reactions. Addition of the IEP allows the splicing reaction to form branched lariat RNPs capable of intron mobility. Here we examine ribozyme splicing, IEP-dependent splicing, and mobility reactions of a group IIC intron from the thermophilic bacterium Thermoanerobacter italicus (Ta.it.I1). We show that Ta.it.I1 is highly active for ribozyme activity, forming linear hydrolytic intron products. Addition of purified IEP switches activity to the canonical lariat forming splicing reaction. We demonstrate that the Ta.it.I1 group IIC intron coordinates the progression of the forward splicing reaction through a π-π' interaction between intron domains II and VI. We further show that branched splicing is supported in the absence of the IEP when the π-π' interaction is mutated. We also investigated the regulation of the two steps of reverse splicing during in...

Source: RNA - March 2, 2020 Category: Genetics & Stem Cells Authors: Smathers CM, Robart AR Tags: RNA Source Type: research