Interaction between the first and last nucleotides of pre-mRNA introns is a determinant of 3' splice site selection in S. cerevisiae.
The splicing of group II and nuclear pre-mRNAs introns occurs via a similar splicing pathway and some of the RNA-RNA interactions involved in these splicing reactions show structural similarities. Recently, genetic analyses performed in a group II intron and the yeast nuclear actin gene suggested that non Watson-Crick interactions between intron boundaries are important for the second splicing step efficiency in both classes of introns. We here show that, in the yeast nuclear rp51A intron, a G to A mutation at the first position activates cryptic 3' splice sites with the sequences UAC/ or UAA/. Moreover, the natural 3' splice site could be reactivated by a G to C substitution of the last intron nucleotide. These results demonstrate that the interaction between the first and last intron nucleotides is a conserved feature of nuclear pre-mRNA splicing in yeast and is involved in the mechanism of 3' splice site selection.
Département de Biologie Moléculaire, Institut Pasteur, Paris, France.
G
G
Chanfreau
P
P
Legrain
B
B
Dujon
A
A
Jacquier
D001483:Base Sequence; D004271:DNA, Fungal; D007438:Introns; D008969:Molecular Sequence Data; D009154:Mutation; D012322:RNA Precursors / Q000235:genetics*; D012326:RNA Splicing; D012331:RNA, Fungal; D012441:Saccharomyces cerevisiae / Q000235:genetics*
D004271:DNA, Fungal; D012322:RNA Precursors; D012331:RNA, Fungal