Journal Article

Structure of a group II intron in complex with its reverse transcriptase

Kaushal, Prem Singh, Qu, Guosheng, Agrawal, Rajendra Kumar, Belfort, Marlene, Wang, Jia, Shigematsu, Hideki, Piazza, Carol Lyn, Wang, Hong-Wei

2016

Overview

A 3.8-Å cryo-EM structure of a bacterial group IIA intron in complex with its intron-encoded protein reveals how the reverse transcriptase domain interacts with the mobile intron RNA as well as structural similarities with eukaryotic telomerase and spliceosomal components. Bacterial group II introns are large catalytic RNAs related to nuclear spliceosomal introns and eukaryotic retrotransposons. They self-splice, yielding mature RNA, and integrate into DNA as retroelements. A fully active group II intron forms a ribonucleoprotein complex comprising the intron ribozyme and an intron-encoded protein that performs multiple activities including reverse transcription, in which intron RNA is copied into the DNA target. Here we report cryo-EM structures of an endogenously spliced Lactococcus lactis group IIA intron in its ribonucleoprotein complex form at 3.8-Å resolution and in its protein-depleted form at 4.5-Å resolution, revealing functional coordination of the intron RNA with the protein. Remarkably, the protein structure reveals a close relationship between the reverse transcriptase catalytic domain and telomerase, whereas the active splicing center resembles the spliceosomal Prp8 protein. These extraordinary similarities hint at intricate ancestral relationships and provide new insights into splicing and retromobility.

• Publisher: Nature Publishing Group US,Nature Publishing Group
• Subject: 101/28 / 631/337/1645/1792 / 631/535/1258/1259 / 82/83 / Bacterial Proteins - chemistry / Bacterial Proteins - metabolism / Biochemistry / Biological Microscopy / Catalysts / Catalytic Domain / Cryoelectron Microscopy / Deoxyribonucleic acid / DNA / Genetic aspects / Introns / Lactococcus / Lactococcus lactis / Lactococcus lactis - chemistry / Lactococcus lactis - metabolism / Lactococcus lactis - ultrastructure / Life Sciences / Membrane Biology / Microscopy / Models, Molecular / Molecular structure / Nucleic Acid Conformation / Observations / Properties / Protein Conformation / Protein Structure / Proteins / Reverse transcriptase / Ribonucleic acid / Ribonucleoproteins / Ribonucleoproteins - chemistry / Ribonucleoproteins - metabolism / Ribonucleoproteins - ultrastructure / RNA / RNA splicing / RNA, Bacterial - chemistry / RNA, Bacterial - metabolism / RNA, Bacterial - ultrastructure / RNA, Catalytic - chemistry / RNA, Catalytic - metabolism / RNA, Catalytic - ultrastructure / RNA-Directed DNA Polymerase - chemistry / RNA-Directed DNA Polymerase - metabolism / Structure