Nuclear and mitochondrial suppression of a mitochondrially inherited cold-sensitive mutation in Aspergillus nidulans.
Partial suppressors of a mitochondrially inherited mutation, [cs-67], conferring cold-sensitivity at 20 degrees C were identified. These mapped at one mitochondrial and four unlinked nuclear loci. Most suppressors partially restored the cytochrome aa3 deficiency of the cold-sensitive strain at 20 degrees C. Strains carrying two or more suppressors and [cs-67] showed considerably impaired growth. This effect was temperature-dependent, being more severe at 37 degrees C, and was not expressed in the presence of the [cs-67+] allele. The cytochrome oxidase activity of one of these strains was no more heat-sensitive than that of the wild-type implying that these mutations did not directly modify cytochrome oxidase. The wild-type strain grown in the presence of chloramphenicol and the cold-sensitive strain grown at 20 degrees C had similar cytochrome spectra and mitochondrial membrane protein profiles on sodium dodecyl sulphate gradient acrylamide gels. [cs-67] conferred pleiotropically a low level of resistance to paramomycin at 37 degrees C. It is suggested that [cs-67] and the suppressors act at the level of the mitochondrial ribosome.
D001233:Aspergillus nidulans / Q000032:analysis / Q000201:enzymology / Q000235:genetics*; D002467:Cell Nucleus; D003080:Cold Temperature; D003580:Cytochromes / Q000032:analysis; D003576:Electron Transport Complex IV / Q000032:analysis; D006358:Hot Temperature; D007425:Intracellular Membranes / Q000032:analysis; D008565:Membrane Proteins / Q000032:analysis; D008928:Mitochondria / Q000032:analysis; D009154:Mutation; D010641:Phenotype; D013489:Suppression, Genetic
D003580:Cytochromes; D008565:Membrane Proteins; D003576:Electron Transport Complex IV