Initiation factor eIF2γ promotes eIF2-GTP-Met-tRNA i Met ternary complex binding to the 40S ribosome

Byung Sik Shin, Joo Ran Kim, Sarah E. Walker, Jinsheng Dong, Jon R. Lorsch, Thomas E. Dever

Research output: Contribution to journalArticlepeer-review

Abstract

In contrast to prokaryotic elongation factor EF-Tu, which delivers aminoacyl-tRNAs to the ribosomal A-site, eukaryotic initiation factor eIF2 binds methionyl initiator transfer RNA (Met-tRNA i Met) to the P-site of the 40S ribosomal subunit. The results of directed hydroxyl radical probing experiments to map binding of Saccharomyces cerevisiae eIF2 on the ribosome and on Met-tRNA i Met revealed that eIF2γ primarily contacts the acceptor stem of Met-tRNA i Met and identified a key binding interface between domain III of eIF2γ and 18S rRNA helix h44 on the 40S subunit. Whereas the analogous domain III of EF-Tu contacts the T stem of tRNAs, biochemical analyses demonstrated that eIF2γ domain III is important for ribosome, not Met-tRNA i Met. Thus, despite their structural similarity, eIF2 and EF-Tu bind tRNAs in substantially different manners, and we propose that the tRNA-binding domain III of EF-Tu has acquired a new ribosome-binding function in eIF2γ.

Original languageEnglish (US)
Pages (from-to)1227-1234
Number of pages8
JournalNature Structural and Molecular Biology
Volume18
Issue number11
DOIs
StatePublished - Nov 2011

ASJC Scopus subject areas

  • Structural Biology
  • Molecular Biology

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