Learn More
Group II introns are novel genetic elements that have properties of both catalytic RNAs and retroelements. Initially identified in organellar genomes of plants and lower eukaryotes, group II introns are now being discovered in increasing numbers in bacterial genomes. Few of the newly sequenced bacterial introns are correctly identified or annotated by those(More)
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(More)
Mobile group II introns encode reverse transcriptases and insert site specifically into intronless alleles (homing). Here, in vitro experiments show that homing of the yeast mtDNA group II intron aI2 occurs by reverse transcription at a double-strand break in the recipient DNA. A site-specific endonuclease cleaves the antisense strand of recipient DNA at(More)
Group II introns are widely believed to have been ancestors of spliceosomal introns, yet little is known about their own evolutionary history. In order to address the evolution of mobile group II introns, we have compiled 71 open reading frames (ORFs) related to group II intron reverse transcriptases and subjected their derived amino acid sequences to(More)
Group II introns are self-splicing RNAs and retroelements found in bacteria and lower eukaryotic organelles. During the past several years, they have been uncovered in surprising numbers in bacteria due to the genome sequencing projects; however, most of the newly sequenced introns are not correctly identified. We have initiated an ongoing web site database(More)
The trnK intron of plants encodes the matK open reading frame (ORF), which has been used extensively as a phylogenetic marker for classification of plants. Here we examined the evolution of the trnK intron itself as a model for group II intron evolution in plants. Representative trnK intron sequences were compiled from species spanning algae to angiosperms,(More)
Bacterial IIC introns are a newly recognized subclass of group II introns whose ribozyme properties have not been characterized in detail. IIC introns are typically located downstream of transcriptional terminator motifs (inverted repeat followed by T's) or other inverted repeats in bacterial genomes. Here we have characterized the self-splicing activity of(More)
The mobility (homing) of the yeast mitochondrial DNA group II intron al2 occurs via target DNA-primed reverse transcription at a double-strand break in the recipient DNA. Here, we show that the site-specific DNA endonuclease that makes the double-strand break is a ribonucleoprotein complex containing the al2-encoded reverse transcriptase protein and excised(More)
Some group II introns are mobile elements as well as catalytic RNAs. Introns aI1 and aI2 found in the gene COX1 in yeast mitochondria encode reverse transcriptases which promote site-specific insertion of the intron into intronless alleles ('homing'). For aI2 this predominantly occurs by reverse transcription of unspliced precursor RNA at a break in(More)
Bordetella bacteriophages generate diversity in a gene that specifies host tropism. This microevolutionary adaptation is produced by a genetic element that combines the basic retroelement life cycle of transcription, reverse transcription and integration with site-directed, adenine-specific mutagenesis. Central to this process is a reverse(More)