Linked Life Data

3032144

Source:http://linkedlifedata.com/resource/pubmed/id/3032144

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:dateCreated
1987-5-12
pubmed:abstractText
Introns of organelle genes share distinctive RNA secondary structures that allow their classification into two known families. These structures are believed to play an essential role in splicing, and members of both structural classes have recently been shown to perform self-splicing reactions in vitro. In lower eukaryotes, many structured introns also contain long internal open reading frames (ORFs), which are able to code for hydrophilic proteins. Several properties of self-splicing structured introns suggest that they resemble mobile genetic elements, even though no actual transposition event involving these introns has yet been found. We report here on the characterization of two intron-encoded proteins that strongly support this attractive idea. First, we show that the class I intron of the 21S ribosomal RNA (rRNA) gene of Saccharomyces cerevisiae omega+ strains (rl intron) encodes a specific transposase. This protein has been partially purified from Escherichia coli cells that overexpress it from an artificial universal code equivalent to the rl intronic ORF. The omega transposase shows a double-strand endonuclease activity in vitro. This activity creates a 4-bp staggered cut with 3' OH overhangs within a specific sequence of the 21S rRNA gene of omega- strains. It is precisely within this sequence that the rl intron inserts by a duplicative transposition. Second, we report on the synthesis, in E. coli, of a putative reverse transcriptase encoded by the class II intron of the cytochrome b gene of Schizosaccharomyces pombe. This synthesis was obtained from E. coli expression vectors, using the class II intronic ORF linked to an artificial initiator sequence. As further support of the idea that structured introns are mobile, we show, from a systematic screening of introns in various yeast species, that the rl intron has transposed into the ATPase subunit 9 gene of Kluyveromyces fragilis. Structural features observed at the new intron homing site may be relevant to the transposition event.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:issn
0090-5542
pubmed:author
pubmed:issnType
Print
pubmed:volume
40
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
5-27
pubmed:dateRevised
2006-11-15
pubmed:meshHeading
pubmed:year
1986
pubmed:articleTitle
Mitochondrial introns as mobile genetic elements: the role of intron-encoded proteins.
pubmed:publicationType
Journal Article, Research Support, Non-U.S. Gov't