title: Nuclear suppressors of the (poky) cytoplasmic mutant in Neurospora crassa. II. Mitochondrial cytochrome systems.
abstract: The mitochondrial cytochrome aa3 and b deficiencies of the [poky] cytoplasmic mutant of Neurospora crassa are partially suppressed by mutant alleles of any one of six nuclear genes, namely sup-1, sup-3, sup-4, sup-5, sup-10 and sup-14. The suppressor-induced increases in the concentration of both cytochromes are detected in the mitochondria from exponentially growing [poky] cultures, and, thus, are clearly distinguishable from the age-dependent changes in the cytochrome system that occur in cultures that approach, or have reached, the stationary phase of growth. The relative amounts of mitochondrial cytochromes aa3 and b show a direct correlation with the relative efficiency of the various sup genes as suppressors of the slow-growth phenotype of [poky]. Since [poky] is defective in mitochondrial protein synthesis due to a lack of 30 S mitochondrial ribosomal subunits, it is proposed that the six suppressors promote the assembly of functional mitochondrial ribosomes.
mesh_terms: D000483:Alleles; D003580:Cytochromes / Q000378:metabolism*; D008928:Mitochondria / Q000378:metabolism*; D009154:Mutation; D009491:Neurospora / Q000254:growth & development*; D009492:Neurospora crassa / Q000254:growth & development*; D012270:Ribosomes / Q000378:metabolism; D013489:Suppression, Genetic
chemical_list: D003580:Cytochromes