Mobile introns in yeast mitochondria
Schäfer, B. and Wolf, K.
Institut für Biologie IV (Mikrobiologie), Rheinisch Westfälische Technische Hochschule Aachen, Worringer Weg, D-52056 Aachen, Germany
The mitochondrial genome of the fission yeast Schizosaccharomyces pombe contains the genes for the two ribosomal RNAs (rnl, rns), a set of tRNAs, three subunits of cytochrome c oxidase (cox1, 2, 3), three subunits of ATPase (atp6, 8, 9), apocytochrome b (cob) and urf a, which presumably codes for a ribosomal protein. Depending on the strain, cox1, cox2 and cob are interrupted by introns. There are 2 group I introns with and 2 without open reading frames in the cox1 gene. Group II introns are found in cox1, cox2 and cob.
We could demonstrate that the group I introns containing open reading frames are mobile genetic elements and that they encode a maturase and an endonuclease. The group II intron in the cob gene is also mobile in crosses. The group II intron in the cox2 gene is remarkable, since there is no example of a group II intron in a mitochondrial cox2 gene in fungi so far. However, group II introns are present in the mitochondrial cox2 genes of monokotyledonous and dikotyledonous plants. It is remarkable that they are inserted at the identical position in fission yeast and in plants. Another outstanding feature is that there are clustered nucleotide changes in the exon regions flanking the mobile group II introns. These changes often lead to rare codons indicating that the intron movement was a recent event.
| LOCATION |
DATE |
TIME |
| Lecture Hall I |
Thursday, April 9 |
05:50 pm |