Evolution of group II introns.

Steven Zimmerly,Cameron Semper

doi:10.1186/s13100-015-0037-5

Abstract

Present in the genomes of bacteria and eukaryotic organelles, group II introns are an ancient class of ribozymes and retroelements that are believed to have been the ancestors of nuclear pre-mRNA introns. Despite long-standing speculation, there is limited understanding about the actual pathway by which group II introns evolved into eukaryotic introns. In this review, we focus on the evolution of group II introns themselves. We describe the different forms of group II introns known to exist in nature and then address how these forms may have evolved to give rise to spliceosomal introns and other genetic elements. Finally, we summarize the structural and biochemical parallels between group II introns and the spliceosome, including recent data that strongly support their hypothesized evolutionary relationship.

Highlights

Investigating the evolution of mobile DNAs involves unique challenges compared to other evolutionary studies
Current data are consistent with the model that the retroelement form was the ancestor of extant group II introns and was the driver for their spread and survival
The evolutionary success of group II introns may be linked to the multifunctionality of their splicing and mobility reactions, which allowed them to spread as selfish DNAs, and derivatize into adaptable forms that shed either splicing or mobility properties

Summary

Introduction

Investigating the evolution of mobile DNAs involves unique challenges compared to other evolutionary studies. Many mobile elements themselves consist of multiple components that may have different evolutionary histories. All of these complicating factors apply to group II introns and must be considered when trying to understand their evolutionary history. Group II intron retroelements consist of an RNA and a protein component. In addition to the 2- to 3-kb retroelement form, group II introns have evolved into many variant forms and spread throughout all domains of life. They are present in bacteria, archaebacteria, mitochondria, and

Objectives

Conclusion