Nuclear control of the expression of the cytochrome b gene in yeast mitochondrial DNA : (apocytochrome b gene, Saccharomyces cerevisiae, CBP1 gene)

Abstract

The mitochondrial gene encoding apocytochrome b is mosaic, containing two intervening sequences in the Saccharomyces cerevisiae strain D273-10B. Five nuclear genes and one mitochondrial gene have been identified that are necessary for the correct processing of the mitochondrial apocytochrome b pre-messenger RNA. The apocytochrome b mRNA from the wild-type strain has been characterized by Northern blot analyses, S1 mapping of the 5' and 3' ends and reverse transcription of the exon/intron boundaries. Apocytochrome b pre-messenger RNA processing has been investigated by Northern blot analyses of RNA from the wild-type strain, mitochondrial mit[superscript -] and p[superscript -] mutant strains and nuclear respiratory deficient pet mutants. CBP1, a nuclear gene complementing one set of pet mutants defective in apocytochrome b mRNA processing, has been cloned and sequenced, revealing an open reading frame that could code for a basic protein of 76,000 daltons.