Mutations in ribosomal protein L10e confer resistance to the fungal-specific eukaryotic elongation factor 2 inhibitor sordarin

• Published in: The Journal of biological chemistry 1999-02, Vol.274 (8), p.4869-4875
• Main Authors: Justice, M.C, Ku, T, Hsu, M.J, Carniol, K, Schmatz, D, Nielsen, J
• Format: Article
• Language: English
• Subjects: alleles; Amino Acid Sequence; amino acid sequences; Antifungal Agents - pharmacology; Base Sequence; binding proteins; Cloning, Molecular; deletions; diterpenoids; DNA, Fungal; Drug Resistance, Microbial - genetics; Eukaryotic Initiation Factor-2 - antagonists & inhibitors; glycosides; Indenes; inhibition; Molecular Sequence Data; Mutation; nucleotide sequences; Phosphoproteins - genetics; protein synthesis inhibitors; proteins; resistance; Ribosomal Proteins - genetics; ribosomes; Saccharomyces cerevisiae; Saccharomyces cerevisiae - drug effects; Saccharomyces cerevisiae - genetics; sordaria arenosa; Sordariales; translocation (plant physiology)
• ISSN: 0021-9258; 1083-351X
• DOI: 10.1074/jbc.274.8.4869

The natural product sordarin, a tetracyclic diterpene glycoside, selectively inhibits fungal protein synthesis by impairing the function of eukaryotic elongation factor 2 (eEF2). Sordarin and its derivatives bind to the eEF2-ribosome-nucleotide complex in sensitive fungi, stabilizing the post-translocational GDP form. We have previously described a class of Saccharomyces cerevisiae mutants that exhibit resistance to varying levels of sordarin and have identified amino acid substitutions in yeast eEF2 that confer sordarin resistance. We now report on a second class of sordarin-resistant mutants. Biochemical and molecular genetic analysis of these mutants demonstrates that sordarin resistance is dependent on the essential large ribosomal subunit protein L10e in S. cerevisiae . Five unique L10e alleles were characterized and sequenced, and several nucleotide changes that differ from the wild-type sequence were identified. Changes that result in the resistance phenotype map to 4 amino acid substitutions and 1 amino acid deletion clustered in a conserved 10-amino acid region of L10e. Like the previously identified eEF2 mutations, the mutant ribosomes show reduced sordarin-conferred stabilization of the eEF2-nucleotide-ribosome complex. To our knowledge, this report provides the first description of ribosomal protein mutations affecting translocation. These results and our previous observations with eEF2 suggest a functional linkage between L10e and eEF2.