Extensive mis-splicing of a bi-partite plant mitochondrial group II intron.
Expression of the seed plant mitochondrial nad5 gene involves two trans-splicing events that remove fragmented group II introns and join the small, central exon c to exons b and d. We show that in both monocot and eudicot plants, extensive mis-splicing of the bi-partite intron 2 takes place, resulting in the formation of aberrantly spliced products in which exon c is joined to various sites within exon b. These mis-spliced products accumulate to levels comparable to or greater than that of the correctly spliced mRNA. We suggest that mis-splicing may result from folding constraints imposed on intron 2 by base-pairing between exon a and a portion of the bi-partite intron 3 downstream of exon c. Consistent with this hypothesis, we find that mis-splicing does not occur in Oenothera mitochondria, where intron 3 is further fragmented such that the predicted base-pairing region is not covalently linked to exon c. Our findings suggest that intron fragmentation may lead to mis-splicing, which may be corrected by further intron fragmentation.
Elina
Helen
H
Department of Biology, McGill University, Montreal, Quebec H3A 1B1, Canada.
Brown
Gregory G
GG
D001483:Base Sequence; D042967:Electron Transport Complex I / Q000235:genetics; D007438:Introns; D008969:Molecular Sequence Data; D009690:Nucleic Acid Conformation; D012313:RNA / Q000737:chemistry* / Q000378:metabolism*; D012333:RNA, Messenger / Q000737:chemistry; D000077278:RNA, Mitochondrial; D018749:RNA, Plant / Q000737:chemistry* / Q000378:metabolism*; D020040:Trans-Splicing
D012333:RNA, Messenger; D000077278:RNA, Mitochondrial; D018749:RNA, Plant; D012313:RNA; D042967:Electron Transport Complex I