A homing endonuclease with a switch: characterization of a twintron encoded homing endonuclease

Fungal Genet Biol. 2014 Apr:65:57-68. doi: 10.1016/j.fgb.2014.01.004. Epub 2014 Feb 5.

Abstract

The small ribosomal subunit gene residing in the mitochondrial DNA of the thermophilic fungus Chaetomium thermophilum var. thermophilum La Touche DSM 1495 is interrupted by a twintron at position mS1247. The mS1247 twintron represents the first mixed twintron found in fungal mtDNA, composed of an external group I intron encoding a LAGLIDADG open reading frame that is interrupted by an internal group II intron. Splicing of the internal group II intron reconstitutes the open reading frame and thus facilitates the expression of the encoded homing endonuclease. The cleavage assays suggest that the twintron encodes an active homing endonuclease that could potentially mobilize the twintron to rns genes that have not yet been invaded by this mobile composite element.

Keywords: Group I intron; Group II intron; Mitochondria; Mobile elements; rDNA.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Chaetomium / genetics*
  • Chaetomium / metabolism
  • DNA, Fungal / genetics
  • DNA, Mitochondrial / genetics
  • Endonucleases / genetics*
  • Endonucleases / metabolism
  • Genes, Fungal
  • Introns
  • Open Reading Frames
  • Phylogeny
  • RNA Splicing
  • Ribosome Subunits, Small / genetics*

Substances

  • DNA, Fungal
  • DNA, Mitochondrial
  • Endonucleases