Details

Autor(en) / Beteiligte

• Simpson, Larry
• Thiemann, Otavio H.
• Savill, Nicholas J.
• Alfonzo, Juan D.
• Maslov, D. A.

Titel

Evolution of RNA Editing in Trypanosome Mitochondria

Ist Teil von

• Proceedings of the National Academy of Sciences - PNAS, 2000-06, Vol.97 (13), p.6986-6993

Ort / Verlag

United States: National Academy of Sciences of the United States of America

Erscheinungsjahr

2000

Link zum Volltext

Quelle

Free E-Journal (出版社公開部分のみ）

Beschreibungen/Notizen

• Two different RNA editing systems have been described in the kinetoplast-mitochondrion of trypanosomatid protists. The first involves the precise insertion and deletion of U residues mostly within the coding regions of maxicircle-encoded mRNAs to produce open reading frames. This editing is mediated by short overlapping complementary guide RNAs encoded in both the maxicircle and the minicircle molecules and involves a series of enzymatic cleavage-ligation steps. The second editing system is a C34to U34modification in the anticodon of the imported tRNATrp, thereby permitting the decoding of the UGA stop codon as tryptophan. U-insertion editing editing probably originated in an ancestor of the kinetoplastid lineage and appears to have evolved in some cases by the replacement of the original pan-edited cryptogene with a partially edited cDNA. The driving force for the evolutionary fixation of these retroposition events was postulated to be the stochastic loss of entire minicircle sequence classes and their encoded guide RNAs upon segregation of the single kinetoplast DNA network into daughter cells at cell division. A large plasticity in the relative abundance of minicircle sequence classes has been observed during cell culture in the laboratory. Computer simulations provide theoretical evidence for this plasticity if a random distribution and segregation model of minicircles is assumed. The possible evolutionary relationship of the C to U and U-insertion editing systems is discussed.