Phosphorylation of the N-terminal domain of ribosomal P-stalk protein uL10 governs its association with the ribosome

The uL10 protein is the main constituent of the ribosomal P-stalk, anchoring the whole stalk to the ribosome through interactions with rRNA. The P-stalk is the core of the GTPase-associated center (GAC), a critical element for ribosome biogenesis and ribosome translational activity. All P-stalk proteins (uL10, P1, and P2) undergo phosphorylation within their C termini. Here, we show that uL10 has multiple phosphorylation sites, mapped also within the N-terminal rRNA-binding domain. Our results reveal that the introduction of a negative charge within the N terminus of uL10 impairs its association with the ribosome. These findings demonstrate that uL10 N-terminal phosphorylation has regulatory potential governing the uL10 interaction with the ribosome and may control the activity of GAC.