Open AccessEvolution of trans-splicing plant mitochondrial introns in pre-Permian times
Author(s) -
Olaf Malek,
Axel Brennicke,
Volker Knoop
Publication year - 1997
Publication title -
proceedings of the national academy of sciences of the united states of america
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 5.011
H-Index - 771
eISSN - 1091-6490
pISSN - 0027-8424
DOI - 10.1073/pnas.94.2.553
Subject(s) - intron , group ii intron , biology , rna splicing , exon , genetics , mitochondrial dna , gene , trans splicing , group i catalytic intron , alternative splicing , rna
Trans-splicing in angiosperm plant mitochondria connects exons from independent RNA molecules by means of group II intron fragments. Homologues of trans-splicing introns in the angiosperm mitochondrialnad2 andnad5 genes are now identified as uninterrupted group II introns in the fernsAsplenium nidus andMarsilea drummondii. These fern introns are correctly spliced from the pre-mRNA at the sites predicted from their well-conserved secondary structures. The flanking exon sequences of thenad2 andnad5 genes in the ferns require RNA editing, including the removal of in-frame stop codons by U-to-C changes for correct expression of the genetic information. We conclude that cis-splicing introns like the ones now identified in ferns are the ancestors of trans-splicing introns in angiosperm mitochondria. Intron disruption is apparently due to a size increase of the structurally variable group II intron domain IV followed by DNA recombination in the plant mitochondrial genome.