title: Insertion of group II intron retroelements after intrinsic transcriptional terminators.
abstract: Mobile DNAs use many mechanisms to minimize damage to their hosts. Here we show that a subclass of group II introns avoids host damage by inserting directly after transcriptional terminator motifs in bacterial genomes (stem-loops followed by Ts). This property contrasts with the site-specific behavior of most group II introns, which insert into homing site sequences. Reconstituted ribonucleo protein particles of the Bacillus halodurans intron B.h.I1 are shown to reverse-splice into DNA targets in vitro but require the DNA to be single-stranded and fold into a stem-loop analogous to the RNA structure that forms during transcription termination. Recognition of this DNA stem-loop motif accounts for in vivo target specificity. Insertion after terminators is a previously unrecognized strategy for a selfish DNA because it prevents interruption of coding sequences and restricts expression of the mobile DNA after integration.
authors.affiliation: Department of Biological Sciences, University of Calgary, 2500 University Drive NW, Calgary, AB, Canada T2N 1N4.
authors.forename: Aaron R
authors.initials: AR
authors.lastname: Robart
authors.forename: Wooseok
authors.initials: W
authors.lastname: Seo
authors.forename: Steven
authors.initials: S
authors.lastname: Zimmerly
mesh_terms: D001407:Bacillus / Q000235:genetics; D004269:DNA, Bacterial / Q000235:genetics / Q000502:physiology; D007438:Introns / Q000235:genetics* / Q000502:physiology; D018626:Retroelements / Q000235:genetics* / Q000502:physiology; D013728:Terminator Regions, Genetic / Q000502:physiology; D014158:Transcription, Genetic
chemical_list: D004269:DNA, Bacterial; D018626:Retroelements