Ribosomal protein L30 of Saccharomyces
cerevisiae binds to a distinct RNA structure to inhibit the
splicing and the translation of its own transcript. Remarkably, the
orthologue of L30 from the archaeon Sulfolobus acidocaldarius
binds specifically to the same RNA fragment and inhibits splicing both
in vitro and in vivo. Indeed, expression of
Sulfolobus L30 in yeast severely reduces growth by limiting
production of the endogenous L30. This conservation of binding
specificity implies that the target of regulation in the RPL30
transcript mimics a site in the rRNA that has been conserved for two
billion years. We identify this site, the first for a ribosomal
protein without a eubacterial orthologue, and suggest that L30 is
responsible for establishing the orientation of a key bridge between
the large and small ribosomal subunits.
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