title: Bacterial group I introns: mobile RNA catalysts.
abstract: Group I introns are intervening sequences that have invaded tRNA, rRNA and protein coding genes in bacteria and their phages. The ability of group I introns to self-splice from their host transcripts, by acting as ribozymes, potentially renders their insertion into genes phenotypically neutral. Some group I introns are mobile genetic elements due to encoded homing endonuclease genes that function in DNA-based mobility pathways to promote spread to intronless alleles. Group I introns have a limited distribution among bacteria and the current assumption is that they are benign selfish elements, although some introns and homing endonucleases are a source of genetic novelty as they have been co-opted by host genomes to provide regulatory functions. Questions regarding the origin and maintenance of group I introns among the bacteria and phages are also addressed.
authors.forename: Georg
authors.initials: G
authors.lastname: Hausner
authors.forename: Mohamed
authors.initials: M
authors.lastname: Hafez
authors.affiliation: Department of Biochemistry, Schulich School of Medicine and Dentistry, Western University, London, ON N6A 5C1, Canada. dedgell@uwo.ca.
authors.forename: David R
authors.initials: DR
authors.lastname: Edgell