A trans-splicing model for the expression of the tripartite nad5 gene in wheat and maize mitochondria.
The mitochondrial single-copy gene nad5 of wheat and maize consists of 5 exons located on three widely separated regions of the genome that are independently transcribed. The first region contains exons I and II separated by an atypical group II intron; in the second region is exon III (only 22 bp long), which is flanked upstream by a maturase-related open reading frame (ORF) and exon e of the nad1 gene, and downstream by a previously unidentified ORF (ORF143); in the third region are exons IV and V separated by a group II intron. In maize, this last domain is flanked upstream by the genes rps12, nad3, and tRNA(Ser) and downstream by a chloroplast tRNA(Cys). RNA editing occurs in wheat exons IV and V as C-to-U changes. A detailed analysis of the transcription of the nad5 gene in wheat and maize reveals that the exons are assembled into a 2.4-kb mRNA after two cis-splicing (between exons I and II and exons IV and V) and two trans-splicing events. The trans-splicing process involves the sequences flanking exons II, III, and IV that feature group II introns. A model is proposed for the assembly and maturation of the nad5 transcripts.
Pereira de Souza
A
A
Laboratoire de Biologie Moléculaire Végétale associé au Centre National de la Recherche Scientifique, UA 1128, Université Paris XI, Orsay, France.
Jubier
M F
MF
Delcher
E
E
Lancelin
D
D
Lejeune
B
B
D000595:Amino Acid Sequence; D001483:Base Sequence; D003001:Cloning, Molecular; D004247:DNA; D005091:Exons; D017343:Genes, Plant; D008928:Mitochondria / Q000378:metabolism*; D024101:Mitochondrial Proteins; D008957:Models, Genetic; D008969:Molecular Sequence Data; D016660:NAD(P)H Dehydrogenase (Quinone) / Q000235:genetics* / Q000378:metabolism; D010940:Plant Proteins / Q000235:genetics* / Q000378:metabolism; D012313:RNA / Q000235:genetics / Q000378:metabolism; D017393:RNA Editing; D012326:RNA Splicing; D015183:Restriction Mapping; D017386:Sequence Homology, Amino Acid; D014908:Triticum / Q000235:genetics*; D003313:Zea mays / Q000235:genetics*
D024101:Mitochondrial Proteins; D010940:Plant Proteins; D012313:RNA; D004247:DNA; D016660:NAD(P)H Dehydrogenase (Quinone)