Elongation factor 4 remodels the A-site tRNA on the ribosome.
During translation, a plethora of protein factors bind to the ribosome and regulate protein synthesis. Many of those factors are guanosine triphosphatases (GTPases), proteins that catalyze the hydrolysis of guanosine 5'-triphosphate (GTP) to promote conformational changes. Despite numerous studies, the function of elongation factor 4 (EF-4/LepA), a highly conserved translational GTPase, has remained elusive. Here, we present the crystal structure at 2.6-Å resolution of the Thermus thermophilus 70S ribosome bound to EF-4 with a nonhydrolyzable GTP analog and A-, P-, and E-site tRNAs. The structure reveals the interactions of EF-4 with the A-site tRNA, including contacts between the C-terminal domain (CTD) of EF-4 and the acceptor helical stem of the tRNA. Remarkably, EF-4 induces a distortion of the A-site tRNA, allowing it to interact simultaneously with EF-4 and the decoding center of the ribosome. The structure provides insights into the tRNA-remodeling function of EF-4 on the ribosome and suggests that the displacement of the CCA-end of the A-site tRNA away from the peptidyl transferase center (PTC) is functionally significant.
Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, CT 06520-8114; Howard Hughes Medical Institute, Yale University, New Haven, CT 06520-8114;
Matthieu G
MG
Gagnon
Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, CT 06520-8114; Howard Hughes Medical Institute, Yale University, New Haven, CT 06520-8114;
Jinzhong
J
Lin
Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, CT 06520-8114; Howard Hughes Medical Institute, Yale University, New Haven, CT 06520-8114; Department of Chemistry, Yale University, New Haven, CT 06520-8107 thomas.steitz@yale.edu.
Thomas A
TA
Steitz
D001665:Binding Sites; D003198:Computer Simulation; D029968:Escherichia coli Proteins / Q000737:chemistry* / Q000648:ultrastructure*; D062105:Molecular Docking Simulation; D009690:Nucleic Acid Conformation; D010448:Peptide Initiation Factors / Q000737:chemistry* / Q000648:ultrastructure*; D011485:Protein Binding; D011487:Protein Conformation; D012329:RNA, Bacterial / Q000737:chemistry* / Q000648:ultrastructure*; D012343:RNA, Transfer / Q000737:chemistry* / Q000648:ultrastructure*; D000071376:RNA-Binding Motifs; D016601:RNA-Binding Proteins / Q000737:chemistry / Q000648:ultrastructure; D012270:Ribosomes
D029968:Escherichia coli Proteins; C515651:LepA protein, E coli; D010448:Peptide Initiation Factors; D012329:RNA, Bacterial; D016601:RNA-Binding Proteins; D012343:RNA, Transfer
elongation factor 4; protein–RNA interactions; remodeling; ribosome; tRNA