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Nmd3 is a structural mimic of eIF 5A, and activates the cp GTP ase Lsg1 during 60S ribosome biogenesis
Author(s) -
Malyutin Andrey G,
Musalgaonkar Sharmishtha,
Patchett Stephanie,
Frank Joachim,
Johnson Arlen W
Publication year - 2017
Publication title -
the embo journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 7.484
H-Index - 392
eISSN - 1460-2075
pISSN - 0261-4189
DOI - 10.15252/embj.201696012
Subject(s) - columbia university , library science , computer science , sociology , media studies
During ribosome biogenesis in eukaryotes, nascent subunits are exported to the cytoplasm in a functionally inactive state. 60S subunits are activated through a series of cytoplasmic maturation events. The last known events in the cytoplasm are the release of Tif6 by Efl1 and Sdo1 and the release of the export adapter, Nmd3, by the GTP ase Lsg1. Here, we have used cryo‐electron microscopy to determine the structure of the 60S subunit bound by Nmd3, Lsg1, and Tif6. We find that a central domain of Nmd3 mimics the translation elongation factor eIF 5A, inserting into the E site of the ribosome and pulling the L1 stalk into a closed position. Additional domains occupy the P site and extend toward the sarcin–ricin loop to interact with Tif6. Nmd3 and Lsg1 together embrace helix 69 of the B2a intersubunit bridge, inducing base flipping that we suggest may activate the GTP ase activity of Lsg1.