title: Yeast ribosomal protein L24 affects the kinetics of protein synthesis and ribosomal protein L39 improves translational accuracy, while mutants lacking both remain viable.
abstract: 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.
authors.affiliation: Laboratory of Biochemistry, School of Medicine, University of Patras, Greece.
authors.forename: J
authors.initials: J
authors.lastname: Dresios
authors.forename: I L
authors.initials: IL
authors.lastname: Derkatch
authors.forename: S W
authors.initials: SW
authors.lastname: Liebman
authors.forename: D
authors.initials: D
authors.lastname: Synetos
mesh_terms: D002455:Cell Division / Q000187:drug effects; D003080:Cold Temperature; D005656:Fungal Proteins / Q000235:genetics / Q000378:metabolism*; D009154:Mutation; D010303:Paromomycin / Q000494:pharmacology; D010455:Peptides / Q000378:metabolism; D010641:Phenotype; D011072:Poly U / Q000378:metabolism; D011132:Polyribosomes / Q000737:chemistry; D014176:Protein Biosynthesis; D012269:Ribosomal Proteins / Q000235:genetics / Q000378:metabolism*; D012441:Saccharomyces cerevisiae / Q000235:genetics / Q000378:metabolism*
chemical_list: D005656:Fungal Proteins; D010455:Peptides; D012269:Ribosomal Proteins; C036298:ribosomal protein L24; C040223:ribosomal protein L39; D011072:Poly U; C012001:polyphenylalanine; D010303:Paromomycin