REVISION OF THE NUCLEOTIDE-SEQUENCE AND RNA SPLICING PATHWAY OF THE NEUROSPORA MITOCHONDRIAL GENE ENCODING ATPASE SUBUNIT-6

Previous sequence analysis of the Neurospora oli2 (ATP6) mitochondrial gene suggested that, in addition to a typical Group-I intron, it cont ained an unusual, mostly-palindromic, 93-nucleotide intron. We report hen revisions of the nucleotide sequence and analysis of the size and sequence of reverse-transcriptase PCR products that show: (1) the Grou p-I intron splice sites are located as predicted by previous DNA seque nce analysis; (2) the putative 93-nt intron is not excised from the ma ture mRNA, and most of this sequence is actually in the 5' untranslate d region. We conclude that the Neurospora ATP6 gene contains only one intron. Analysis of the cDNA sequence also confirms the non-universal nature of the Neurospora mitochondrial genetic code: a TGA codon infer red from the DNA sequence is present as UGA in the mRNA. This provides direct evidence that this codon is not altered, for example by RNA ed iting, to conform to the universal code.