title: Intron mobility in the T-even phages: high frequency inheritance of group I introns promoted by intron open reading frames.
abstract: Intron mobility in the T-even phages has been demonstrated. Efficient nonreciprocal conversion of intron minus (In-) alleles to intron plus (In+) occurred for the td and sunY genes, but not for nrdB. Conversion to In+ was absolutely dependent on expression of the respective intron open reading frame (ORF). Introns were inserted at their cognate sites in an intronless phage genome via an RNA-independent, DNA-based, duplicative recombination event that was stimulated by exon homology. The td intron ORF product directs the endonucleolytic cleavage of DNA, targeting the site of intron integration. A 21 nucleotide deletion of the integration site abolished high frequency intron inheritance. These experiments provide a novel example of gene conversion in prokaryotes, while suggesting a molecular rationale for the inconsistent distribution of introns within highly conserved exon contexts of the T-even phage genomes.
authors.affiliation: Wadsworth Center for Laboratories and Research, New York State Department of Health, Albany 12201-0509.
authors.forename: S M
authors.initials: SM
authors.lastname: Quirk
authors.forename: D
authors.initials: D
authors.lastname: Bell-Pedersen
authors.forename: M
authors.initials: M
authors.lastname: Belfort
mesh_terms: D003001:Cloning, Molecular; D004926:Escherichia coli / Q000235:genetics*; D005091:Exons; D014644:Genetic Variation; D007438:Introns; D015345:Oligonucleotide Probes; D010957:Plasmids; D011401:Promoter Regions, Genetic; D012326:RNA Splicing; D011995:Recombination, Genetic; D013604:T-Phages / Q000235:genetics*
chemical_list: D015345:Oligonucleotide Probes