Structural basis for interaction of the ribosome with the switch regions of GTP-bound elongation factors.
Elongation factor G (EF-G) catalyzes tRNA translocation on the ribosome. Here a cryo-EM reconstruction of the 70S*EF-G ribosomal complex at 7.3 A resolution and the crystal structure of EF-G-2*GTP, an EF-G homolog, at 2.2 A resolution are presented. EF-G-2*GTP is structurally distinct from previous EF-G structures, and in the context of the cryo-EM structure, the conformational changes are associated with ribosome binding and activation of the GTP binding pocket. The P loop and switch II approach A2660-A2662 in helix 95 of the 23S rRNA, indicating an important role for these conserved bases. Furthermore, the ordering of the functionally important switch I and II regions, which interact with the bound GTP, is dependent on interactions with the ribosome in the ratcheted conformation. Therefore, a network of interaction with the ribosome establishes the active GTP conformation of EF-G and thus facilitates GTP hydrolysis and tRNA translocation.
Connell
Sean R
SR
Institut für Medizinische Physik und Biophysik, Charite-Universitätsmedizin Berlin, Ziegelstrasse 5-9, 10117 Berlin, Germany.
Takemoto
Chie
C
Wilson
Daniel N
DN
Wang
Hongfei
H
Murayama
Kazutaka
K
Terada
Takaho
T
Shirouzu
Mikako
M
Rost
Maximilian
M
Schüler
Martin
M
Giesebrecht
Jan
J
Dabrowski
Marylena
M
Mielke
Thorsten
T
Fucini
Paola
P
Yokoyama
Shigeyuki
S
Spahn
Christian M T
CM
D001665:Binding Sites; D020285:Cryoelectron Microscopy; D018360:Crystallography, X-Ray; D006160:Guanosine Triphosphate / Q000378:metabolism*; D006165:Guanylyl Imidodiphosphate / Q000378:metabolism; D008958:Models, Molecular; D020653:Peptide Elongation Factor G / Q000737:chemistry* / Q000378:metabolism* / Q000648:ultrastructure; D017433:Protein Structure, Secondary; D017434:Protein Structure, Tertiary; D012270:Ribosomes / Q000737:chemistry* / Q000378:metabolism* / Q000648:ultrastructure; D013329:Structure-Activity Relationship; D016963:Thermus thermophilus / Q000378:metabolism*
D020653:Peptide Elongation Factor G; D006165:Guanylyl Imidodiphosphate; D006160:Guanosine Triphosphate