Trans-splicing of organelle introns--a detour to continuous RNAs

Bioessays. 2009 Sep;31(9):921-34. doi: 10.1002/bies.200900036.


In eukaryotes, RNA trans-splicing is an important RNA-processing form for the end-to-end ligation of primary transcripts that are derived from separately transcribed exons. So far, three different categories of RNA trans-splicing have been found in organisms as diverse as algae to man. Here, we review one of these categories: the trans-splicing of discontinuous group II introns, which occurs in chloroplasts and mitochondria of lower eukaryotes and plants. Trans-spliced exons can be predicted from DNA sequences derived from a large number of sequenced organelle genomes. Further molecular genetic analysis of mutants has unravelled proteins, some of which being part of high-molecular-weight complexes that promote the splicing process. Based on data derived from the alga Chlamydomonas reinhardtii, a model is provided which defines the composition of an organelle spliceosome. This will have a general relevance for understanding the function of RNA-processing machineries in eukaryotic organelles.

Publication types

  • Research Support, Non-U.S. Gov't
  • Review

MeSH terms

  • Animals
  • Chlamydomonas reinhardtii / genetics
  • Chlamydomonas reinhardtii / metabolism
  • Chloroplasts / genetics
  • Chloroplasts / metabolism*
  • Humans
  • Introns*
  • Mitochondria / genetics
  • Mitochondria / metabolism*
  • Nucleic Acid Conformation
  • RNA / chemistry
  • RNA / genetics*
  • Spliceosomes / genetics
  • Trans-Splicing*


  • RNA