Group II introns : evolution, structure and function

Group II introns are mobile, self-splicing ribozymes found in bacteria, archaea and eukaryotic organelles. They are widely believed to be the progenitors of the eukaryotic spliceosomal introns and retroelements. Yet many structural and evolutionary aspects of group II introns remain elusive. Indeed, while group II introns are the putative forerunners of spliceosomal introns in eukaryotes, they are notably absent in the nuclear genomes and a large portion of prokaryotes. Furthermore, although the architecture of a post-catalytic group II intron holoenzyme containing both the RNA and the bound intron encoded protein (IEP) has been solved by cryo-electron microscopy (cryo-EM), the interactions among the RNA and protein components that define the functionality of the RNP stays largely unelucidated, mainly because the structure of the pre-catalytic RNP was unsolved. In this work, efforts were made to address such questions, with a focus on the evolution, structure and function of group II introns.