The self-splicing intron in the Neurospora apocytochrome b gene contains a long reading frame in frame with the upstream exon.
We have determined the DNA sequence of intron 1 and flanking exons in the mitochondrial apocytochrome b gene of the Neurospora laboratory strain 74A and the natural isolate North Africa. In contrast to a previous report, we find that this intron contains an open reading frame (ORF) of 951 bases in frame with the upstream exon. The putative intron-encoded protein resembles those of other intron ORFs with respect to length, calculated isoelectric point, and proportion of basic, acidic, polar, and non-polar amino acids; however, no amino acid sequences resembling the "decapeptides" characteristic of maturase-like ORFs were found. Coupled with the previous finding that this intron is capable of self-splicing in vitro in the absence of proteins, the observations discussed here raise the possibility that other introns with long, in-frame ORFs may also be capable of RNA-catalyzed splicing in vitro.
D000595:Amino Acid Sequence; D001059:Apoproteins / Q000235:genetics*; D001483:Base Sequence; D003573:Cytochrome b Group / Q000235:genetics*; D045303:Cytochromes b; D004271:DNA, Fungal / Q000235:genetics; D004272:DNA, Mitochondrial / Q000235:genetics; D005091:Exons; D005656:Fungal Proteins / Q000235:genetics*; D005800:Genes, Fungal; D007438:Introns; D008969:Molecular Sequence Data; D009491:Neurospora / Q000235:genetics*; D009492:Neurospora crassa / Q000201:enzymology / Q000235:genetics*; D012326:RNA Splicing; D012331:RNA, Fungal / Q000235:genetics; D012333:RNA, Messenger / Q000235:genetics
D001059:Apoproteins; D003573:Cytochrome b Group; D004271:DNA, Fungal; D004272:DNA, Mitochondrial; D005656:Fungal Proteins; D012331:RNA, Fungal; D012333:RNA, Messenger; D045303:Cytochromes b