Yeast ribosomal protein L24 affects the kinetics of protein synthesis and ribosomal protein L39 improves translational accuracy, while mutants lacking both remain viable

Biochemistry. 2000 Jun 20;39(24):7236-44. doi: 10.1021/bi9925266.


Four mutant strains from Saccharomyces cerevisiae were used to study ribosome structure and function. They included a strain carrying deletions of the two genes encoding ribosomal protein L24, a strain carrying a mutation spb2 in the gene for ribosomal protein L39, a strain carrying a deletion of the gene for L39, and a mutant lacking both L24 and L39. The mutant lacking only L24 showed just 25% of the normal polyphenylalanine-synthesizing activity followed by a decrease in P-site binding, suggesting the possibility that protein L24 is involved in the kinetics of translation. Each of the two L39 mutants displayed a 4-fold increase of their error frequencies over the wild type. This was accompanied by a substantial increase in A-site binding, typical of error-prone mutants. The absence of L39 also increased sensitivity to paromomycin, decreased the ribosomal subunit ratio, and caused a cold-sensitive phenotype. Mutant cells lacking both ribosomal proteins remained viable. Their ribosomes showed reduced initial rates caused by the absence of L24 but a normal extent of polyphenylalanine synthesis and a substantial in vivo reduction in the amount of 80S ribosomes compared to wild type. Moreover, this mutant displayed decreased translational accuracy, hypersensitivity to the antibiotic paromomycin, and a cold-sensitive phenotype, all caused mainly by the deletion of L39. Protein L39 is the first protein of the 60S ribosomal subunit implicated in translational accuracy.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Cell Division / drug effects
  • Cold Temperature
  • Fungal Proteins / genetics
  • Fungal Proteins / metabolism*
  • Mutation
  • Paromomycin / pharmacology
  • Peptides / metabolism
  • Phenotype
  • Poly U / metabolism
  • Polyribosomes / chemistry
  • Protein Biosynthesis
  • Ribosomal Proteins / genetics
  • Ribosomal Proteins / metabolism*
  • Saccharomyces cerevisiae / genetics
  • Saccharomyces cerevisiae / metabolism*


  • Fungal Proteins
  • Peptides
  • Ribosomal Proteins
  • ribosomal protein L24
  • ribosomal protein L39
  • Poly U
  • polyphenylalanine
  • Paromomycin