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Histidine methylation of yeast ribosomal protein Rpl3p is required for proper 60S subunit assembly (LB185)
Author(s) -
AlHadid Qais,
Roy Kevin,
Chanfreau Guillaume,
Clarke Steven
Publication year - 2014
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.28.1_supplement.lb185
Subject(s) - ribosome , ribosome biogenesis , ribosomal protein , ribosomal rna , biochemistry , biology , eukaryotic large ribosomal subunit , eukaryotic ribosome , methylation , eukaryotic small ribosomal subunit , methyltransferase , protein subunit , microbiology and biotechnology , rna , gene
Histidine protein methylation is an unusual posttranslational modification. In the yeast Saccharomyces cerevisiae, the large ribosomal subunit protein Rpl3p is methylated at histidine‐243, a residue that contacts the 25S rRNA near the P‐site. Rpl3p methylation is dependent upon Hpm1p, a candidate seven beta strand methyltransferase. In this study, we characterized Hpm1p activity in vitro and in vivo. Amino acid analysis of cell lysates and subcellular fractions reveals that Hpm1p is responsible for all detectable histidine protein methylation. The modification is found in a polypeptide corresponding to the size of Rpl3p in ribosomes and in a nuclei‐containing organelle fraction, but was not detected in proteins of the ribosome‐free cytosol fraction. In vitro assays demonstrate that Hpm1p is a methyltransferase that catalyzes the modification of ribosome‐associated but not free Rpl3p, suggesting that its activity depends on interactions of Rpl3p with other ribosomal components. hpm1 null mutant cells are defective in early rRNA processing resulting in a deficiency of 60S subunits and decreased translational activity in minimal media. Finally, cells lacking Hpm1p are resistant to cycloheximide, indicative of ribosome structure abnormalities. We propose that Hpm1p plays a role in orchestrating the assembly of biogenesis factors during early ribosome assembly. Grant Funding Source : NIH