title: Initiation factor eIF2γ promotes eIF2-GTP-Met-tRNAi(Met) ternary complex binding to the 40S ribosome.
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.
authors: Laboratory of Gene Regulation and Development, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland, USA.
authors: Byung-Sik
authors: BS
authors: Shin
authors: Joo-Ran
authors: JR
authors: Kim
authors: Sarah E
authors: SE
authors: Walker
authors: Jinsheng
authors: J
authors: Dong
authors: Jon R
authors: JR
authors: Lorsch
authors: Thomas E
authors: TE
authors: Dever
mesh_terms: D019843:Archaeal Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D003545:Cysteine / Q000235:genetics; D015852:Eukaryotic Initiation Factor-2 / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D006160:Guanosine Triphosphate / Q000737:chemistry / Q000378:metabolism*; D017665:Hydroxyl Radical / Q000378:metabolism; D008958:Models, Molecular; D008969:Molecular Sequence Data; D009690:Nucleic Acid Conformation; D010444:Peptide Elongation Factor Tu / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D012337:RNA, Ribosomal, 18S / Q000737:chemistry / Q000378:metabolism; D012358:RNA, Transfer, Met / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D054682:Ribosome Subunits, Small, Eukaryotic / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D029701:Saccharomyces cerevisiae Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism
chemical_list: D019843:Archaeal Proteins; D015852:Eukaryotic Initiation Factor-2; C112736:Met-tRNA(i)(Met); D012337:RNA, Ribosomal, 18S; D012358:RNA, Transfer, Met; D029701:Saccharomyces cerevisiae Proteins; D017665:Hydroxyl Radical; D006160:Guanosine Triphosphate; D010444:Peptide Elongation Factor Tu; D003545:Cysteine