Genetic and biochemical characterization of Cu,Zn superoxide dismutase mutants in Saccharomyces cerevisiae

J Biol Chem. 1991 Mar 5;266(7):4417-24.


The allele scd 1 is a recessive chromosomal mutation in Saccharomyces cerevisiae that eliminates Cu,Zn superoxide dismutase (SOD-1) activity. SOD-1- strains are unable to grow in 100% O2 in rich medium and are methionine and lysine auxotrophic when grown in air (Bilinski, T., Krawiec, Z., Liczmanski, A., and Litwinska, J. (1985) Biochem. Biophys. Res. Commun. 130, 533-539). In this report, scd1 was genetically mapped to the right arm of chromosome X, 11 centimorgans proximal to cdc11. The gene for SOD-1 (SOD1) was physically mapped by Southern blot to restriction fragments containing CDC11. scd1 failed to complement a complete deletion of SOD1. Thus, scd1 maps to the SOD1 locus and is designated sod1-1. The molecular basis for the lack of SOD-1 activity in sodl-1 carrying strains has also been established. The size and amount of SOD-1 mRNA in the mutant were essentially the same as in wild type cells. Western blot analysis showed that the SOD-1 dimer and 16-kilodalton subunit that co-migrated electrophoretically with wild type yeast SOD-1 were abundant in mutant cell extracts. However, two additional SOD-1 immunoreactive polypeptides were detected in these extracts in both denaturing and nondenaturing gels. None of the SOD-1 immunoreactive species in the mutant extracts exhibited superoxide dismutase activity. Transformants of the mutant strain carrying episomal, wild type SOD1 expressed wild type, active SOD-1 protein, indicating that the mutant allele had no discernible effect on the correct synthesis and activation of apoSOD-1. Size exclusion chromatography of soluble cell extracts derived from wild type and SOD1 deletion strains identified a copper binding peak that corresponded to SOD-1. This copper-binding fraction was absent in cell extracts from the sod1-1-containing strain although Western blot analysis of the corresponding chromatographic fractions showed that SOD-1 polypeptide was present in these fractions. Sequence data derived from the cloned genes showed that sod1-1 differed from SOD1 only in the adjacent 5'-noncoding region. The biochemical data indicate that this genetic alteration results in the synthesis of a collection of SOD-1 polypeptides that fail to bind copper and may also fail to completely self-associate. Both phenotypes could be due to the inability of these polypeptides to adopt the native SOD-1 conformation.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Alleles
  • Base Sequence
  • Blotting, Northern
  • Blotting, Western
  • Catalase / metabolism
  • Chromosome Mapping
  • Copper / metabolism
  • Genetic Complementation Test
  • Molecular Sequence Data
  • Mutation
  • RNA, Fungal / genetics
  • RNA, Messenger / genetics
  • Saccharomyces cerevisiae / enzymology
  • Saccharomyces cerevisiae / genetics*
  • Superoxide Dismutase / chemistry
  • Superoxide Dismutase / genetics*
  • Superoxide Dismutase / metabolism
  • Transcription, Genetic


  • RNA, Fungal
  • RNA, Messenger
  • Copper
  • Catalase
  • Superoxide Dismutase

Associated data

  • GENBANK/M61694
  • GENBANK/M61695
  • GENBANK/M61696
  • GENBANK/M61697
  • GENBANK/M61698
  • GENBANK/M64233
  • GENBANK/M64234
  • GENBANK/M64235
  • GENBANK/M64236
  • GENBANK/M64394