Drop-off-reinitiation triggered by EF-G-driven mistranslocation and its alleviation by EF-P.

Kenya Tajima, Takayuki Katoh, Hiroaki Suga

Nucleic acids research 2022 Mar 21

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In ribosomal translation, peptidyl transfer occurs between P-site peptidyl-tRNA and A-site aminoacyl-tRNA, followed by translocation of the resulting P-site deacylated-tRNA and A-site peptidyl-tRNA to E and P site, respectively, mediated by EF-G. Here, we report that mistranslocation of P-site peptidyl-tRNA and A-site aminoacyl-tRNA toward E and A site occurs when high concentration of EF-G triggers the migration of two tRNAs prior to completion of peptidyl transfer. Consecutive incorporation of less reactive amino acids, such as Pro and d-Ala, makes peptidyl transfer inefficient and thus induces the mistranslocation event. Consequently, the E-site peptidyl-tRNA drops off from ribosome to give a truncated peptide lacking the C-terminal region. The P-site aminoacyl-tRNA allows for reinitiation of translation upon accommodation of a new aminoacyl-tRNA at A site, leading to synthesis of a truncated peptide lacking the N-terminal region, which we call the 'reinitiated peptide'. We also revealed that such a drop-off-reinitiation event can be alleviated by EF-P that promotes peptidyl transfer of Pro. Moreover, this event takes place both in vitro and in cell, showing that reinitiated peptides during protein synthesis could be accumulated in this pathway in cells. © The Author(s) 2022. Published by Oxford University Press on behalf of Nucleic Acids Research.

Citation

Kenya Tajima, Takayuki Katoh, Hiroaki Suga. Drop-off-reinitiation triggered by EF-G-driven mistranslocation and its alleviation by EF-P. Nucleic acids research. 2022 Mar 21;50(5):2736-2753