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Characterization of the 26S rRNA‐binding domain in Saccharomyces cerevisiae ribosomal stalk phosphoprotein P0
Author(s) -
Santos Cruz,
Ballesta Juan P. G.
Publication year - 2005
Publication title -
molecular microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.857
H-Index - 247
eISSN - 1365-2958
pISSN - 0950-382X
DOI - 10.1111/j.1365-2958.2005.04816.x
Subject(s) - biology , ribosome , ribosomal rna , saccharomyces cerevisiae , rna , eukaryotic ribosome , ribosomal protein , stalk , transfer rna , 5.8s ribosomal rna , rna binding protein , biochemistry , genetics , microbiology and biotechnology , yeast , gene , horticulture
Summary The stalk is a universal structure of the large ribosomal subunit involved in the function of translation factors. The bacterial stalk is highly stable but its stability is notably reduced in eukaryotes, favouring a translation regulatory activity of this ribosomal domain, which has not been reported in prokaryotes. The RNA‐binding protein P0 plays a key role in determining the eukaryotic stalk activities, and characterization of the P0/RNA interaction is essential to understand the evolutionary process. Using a series of Saccharomyces cerevisiae ‐truncated proteins, a direct involvement of two N‐terminal regions, I 3 ‐M 58 and K 81 ‐V 121 , in the interaction of P0 with the ribosome has been shown. Two other conserved regions, R 122 ‐T 149 and G 162 ‐T 182 , affect P0 interaction with other stalk components and the sensitivity to sordarin anti‐fungals but are not essential for RNA binding. Moreover, P0 and a P0 fragment comprising only the first 121 amino acids show a similar in vitro affinity for the highly conserved 26S rRNA binding site. A protein chimera containing the first 165 amino acids of L10, the P0 bacterial counterpart, is able to complement the absence of P0 and also shows the same P0 RNA binding characteristics. Altogether, the results indicate that the affinity of the stalk RNA‐binding protein for its substrate has been highly conserved, and changes in the stability of the interaction of P0 with the ribosome, which are essential for the new eukaryotic functions, result from the evolution of the overall stalk structure.