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The ribosomal stalk complex plays a crucial role in delivering translation factors to the catalytic site of the ribosome. It has a very similar architecture in all cells, although the protein components in bacteria are unrelated to those in archaea and eukaryotes. Here we used mass spectrometry to investigate ribosomal stalk complexes from bacteria, eukaryotes, and archaea in situ on the ribosome. Specifically we targeted ribosomes with different optimal growth temperatures. Our results showed that for the mesophilic bacterial ribosomes we investigated the stalk complexes are exclusively pentameric or entirely heptameric in the case of thermophilic bacteria, whereas we observed only pentameric stalk complexes in eukaryotic species. We also found the surprising result that for mesophilic archaea, Methanococcus vannielii, Methanococcus maripaludis, and Methanosarcina barkeri, both pentameric and heptameric stoichiometries are present simultaneously within a population of ribosomes. Moreover the ratio of pentameric to heptameric stalk complexes changed during the course of cell growth. We consider these differences in stoichiometry within ribosomal stalk complexes in the context of convergent evolution.

Original publication

DOI

10.1074/mcp.M000072-MCP201

Type

Journal article

Journal

Mol Cell Proteomics

Publication Date

08/2010

Volume

9

Pages

1774 - 1783

Keywords

Animals, Archaea, Eukaryota, Molecular Weight, Phylogeny, Ribosomal Proteins, Ribosomes, Tandem Mass Spectrometry, Temperature, Thermus thermophilus