The ubiquitination-deubiquitination cycle on the ribosomal protein eS7A is crucial for efficient translation

Ubiquitination is a major post-translational modification of ribosomal proteins. The role of ubiquitination in the regulation of ribosome functions is still being elucidated. However, the importance of ribosome deubiquitination remains unclear. Here, we show that the cycle of ubiquitination and deubiquitination of the 40S ribosome subunit eS7 is important for efficient translation. eS7 ubiquitination at lysine 83 is required for efficient protein translation. We identified Otu2 and Ubp3 as the deubiquitinating enzymes for eS7. An otu2 Delta ubp3 Delta mutation caused a defect in protein synthesis. Ubp3 inhibited polyubiquitination of eS7 in polysomes to keep eS7 in a mono-ubiquitinated form, whereas Otu2 was specifically bound to the free 40S ribosome and promoted the dissociation of mRNAs from 40S ribosomes in the recycling step. Our results provide clues for understanding the molecular mechanism of the translation system via a ubiquitination-deubiquitination cycle.

Automated summary

Ubiquitination and deubiquitination cycle of ribosomal proteins play a crucial role in efficient protein translation. Ubiquitination at lysine 83 of eS7 is important for translation efficiency, with Otu2 and Ubp3 identified as the deubiquitinating enzymes. Ubp3 inhibits polyubiquitination to maintain eS7 in a mono-ubiquitinated form, while Otu2 promotes mRNA dissociation from 40S ribosomes in the recycling step.