title: Splicing of a group II intron involved in the conjugative transfer of pRS01 in lactococci.
abstract: Analysis of a region involved in the conjugative transfer of the lactococcal conjugative element pRS01 has revealed a bacteria] group II intron. Splicing of this lactococcal intron (designated Ll.ltrB) in vivo resulted in the ligation of two exon messages (ltrBE1 and ltrBE2) which encoded a putative conjugative relaxase essential for the transfer of pRS01. Like many group II introns, the Ll.ltrB intron possessed an open reading frame (ltrA) with homology to reverse transcriptases. Remarkably, sequence analysis of ltrA suggested a greater similarity to open reading frames encoded by eukaryotic mitochondrial group II introns than to those identified to date from other bacteria. Several insertional mutations within ltrA resulted in plasmids exhibiting a conjugative transfer-deficient phenotype. These results provide the first direct evidence for splicing of a prokaryotic group II intron in vivo and suggest that conjugative transfer is a mechanism for group II intron dissemination in bacteria.
authors.affiliation: Department of Microbiology and Institute for Advanced Studies in Biological Process Technology, University of Minnesota, Minneapolis 55455-0312, USA.
authors.forename: D A
authors.initials: DA
authors.lastname: Mills
authors.forename: L L
authors.initials: LL
authors.lastname: McKay
authors.forename: G M
authors.initials: GM
authors.lastname: Dunny
mesh_terms: D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000235:genetics*; D001483:Base Sequence; D003227:Conjugation, Genetic; D004251:DNA Transposable Elements; D004269:DNA, Bacterial / Q000235:genetics*; D004706:Endodeoxyribonucleases / Q000235:genetics; D007438:Introns; D013294:Lactococcus lactis / Q000235:genetics*; D008969:Molecular Sequence Data; D009690:Nucleic Acid Conformation; D010802:Phylogeny; D010957:Plasmids; D012326:RNA Splicing; D012329:RNA, Bacterial / Q000235:genetics*; D012194:RNA-Directed DNA Polymerase; D012441:Saccharomyces cerevisiae / Q000235:genetics; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid
chemical_list: D001426:Bacterial Proteins; D004251:DNA Transposable Elements; D004269:DNA, Bacterial; C099786:LtrB protein, Lactococcus lactis; D012329:RNA, Bacterial; C099785:LtrA protein, Lactococcus lactis; D012194:RNA-Directed DNA Polymerase; D004706:Endodeoxyribonucleases