title: Locking and unlocking of ribosomal motions.
abstract: During the ribosomal translocation, the binding of elongation factor G (EF-G) to the pretranslocational ribosome leads to a ratchet-like rotation of the 30S subunit relative to the 50S subunit in the direction of the mRNA movement. By means of cryo-electron microscopy we observe that this rotation is accompanied by a 20 A movement of the L1 stalk of the 50S subunit, implying that this region is involved in the translocation of deacylated tRNAs from the P to the E site. These ribosomal motions can occur only when the P-site tRNA is deacylated. Prior to peptidyl-transfer to the A-site tRNA or peptide removal, the presence of the charged P-site tRNA locks the ribosome and prohibits both of these motions.
authors.affiliation: Howard Hughes Medical Institute, and Health Research Incororated at the Wadswoth Center, State University of New York, Albany, 12201, USA.
authors.forename: Mikel
authors.initials: M
authors.lastname: Valle
authors.forename: Andrey
authors.initials: A
authors.lastname: Zavialov
authors.forename: Jayati
authors.initials: J
authors.lastname: Sengupta
authors.forename: Urmila
authors.initials: U
authors.lastname: Rawat
authors.forename: Måns
authors.initials: M
authors.lastname: Ehrenberg
authors.forename: Joachim
authors.initials: J
authors.lastname: Frank
mesh_terms: D001665:Binding Sites / Q000235:genetics; D020285:Cryoelectron Microscopy; D005057:Eukaryotic Cells / Q000378:metabolism* / Q000648:ultrastructure; D008958:Models, Molecular; D008968:Molecular Conformation; D020653:Peptide Elongation Factor G / Q000235:genetics / Q000378:metabolism*; D010455:Peptides / Q000235:genetics / Q000378:metabolism; D014176:Protein Biosynthesis / Q000235:genetics*; D017434:Protein Structure, Tertiary / Q000235:genetics; D021122:Protein Subunits / Q000235:genetics / Q000378:metabolism; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism* / Q000648:ultrastructure; D012343:RNA, Transfer / Q000235:genetics / Q000378:metabolism* / Q000648:ultrastructure; D012270:Ribosomes / Q000235:genetics / Q000378:metabolism* / Q000648:ultrastructure; D012399:Rotation
chemical_list: D020653:Peptide Elongation Factor G; D010455:Peptides; D021122:Protein Subunits; D012333:RNA, Messenger; D012343:RNA, Transfer