Multiplication of Ribosomal P-Stalk Proteins Contributes to the Fidelity of Translation

ABSTRACT

The P-stalk represents a vital element within the ribosomal GTPase-associated center, which represents a landing platform for translational GTPases. The eukaryotic P-stalk exists as a uL10-(P1-P2)₂ pentameric complex, which contains five identical C-terminal domains, one within each protein, and the presence of only one such element is sufficient to stimulate factor-dependent GTP hydrolysis in vitro and to sustain cell viability. The functional contribution of the P-stalk to the performance of the translational machinery in vivo, especially the role of P-protein multiplication, has never been explored. Here, we show that ribosomes depleted of P1/P2 proteins exhibit reduced translation fidelity at elongation and termination steps. The elevated rate of the decoding error is inversely correlated with the number of the P-proteins present on the ribosome. Unexpectedly, the lack of P1/P2 has little effect in vivo on the efficiency of other translational GTPase (trGTPase)-dependent steps of protein synthesis, including translocation. We have shown that loss of accuracy of decoding caused by P1/P2 depletion is the major cause of translation slowdown, which in turn affects the metabolic fitness of the yeast cell. We postulate that the multiplication of P-proteins is functionally coupled with the qualitative aspect of ribosome action, i.e., the recoding phenomenon shaping the cellular proteome.

KEYWORDS:

• ribosomal proteins
• ribosomal stalk
• ribosome

SUPPLEMENTAL MATERIAL

Supplemental material for this article may be found at https://doi.org/10.1128/MCB.00060-17.

ACKNOWLEDGMENTS

We gratefully acknowledge the use of the facilities of the Ecotech-Complex in Lublin, under project number UDA-POIG.02.01.00-06-212/09-03. We are indebted to Marina Rodnina for critical reading of the manuscript.

This work was supported by a grant from the National Science Center in Poland (UMO-2014/13/B/NZ1/00953) to M.T.

We declare that they we have no conflicts of interest with the contents of this article.

L.W. designed, analyzed, and interpreted the data and wrote the manuscript, E.M. contributed to Fig. 1B, 2 through 7, and 9, M.S. contributed to Fig. 7 and 8, B.M.-W. contributed to Fig. 1D, M.M. contributed to Fig. 1C, P.G. contributed to Fig. 1A and 9A, A.B. contributed to Fig. 2, L.B. contributed to Fig. 7, and M.T. conceived the study, analyzed and interpreted the data, and wrote the manuscript.