title: Evolution of group II introns.
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.
authors.affiliation: Department of Biological Sciences, University of Calgary, 2500 University Drive N.W., Calgary, Alberta T2N 1N4 Canada.
authors.forename: Steven
authors.initials: S
authors.lastname: Zimmerly
authors.affiliation: Department of Biological Sciences, University of Calgary, 2500 University Drive N.W., Calgary, Alberta T2N 1N4 Canada.
authors.forename: Cameron
authors.initials: C
authors.lastname: Semper
keywords: Mobile DNA; Molecular evolution; Retroelement; Ribozyme; Spliceosome