title: Mechanism for the disassembly of the posttermination complex inferred from cryo-EM studies.
abstract: Ribosome recycling, the disassembly of the posttermination complex after each round of protein synthesis, is an essential step in mRNA translation, but its mechanism has remained obscure. In eubacteria, recycling is catalyzed by RRF (ribosome recycling factor) and EF-G (elongation factor G). By using cryo-electron microscopy, we have obtained two density maps, one of the RRF bound posttermination complex and one of the 50S subunit bound with both EF-G and RRF. Comparing the two maps, we found domain I of RRF to be in the same orientation, while domain II in the EF-G-containing 50S subunit is extensively rotated (approximately 60 degrees) compared to its orientation in the 70S complex. Mapping the 50S conformation of RRF onto the 70S posttermination complex suggests that it can disrupt the intersubunit bridges B2a and B3, and thus effect a separation of the two subunits. These observations provide the structural basis for the mechanism by which the posttermination complex is split into subunits by the joint action of RRF and EF-G.
authors.affiliation: Wadsworth Center, State University of New York at Albany, Empire State Plaza, Albany, New York 12201, USA.
authors.forename: Ning
authors.initials: N
authors.lastname: Gao
authors.forename: Andrey V
authors.initials: AV
authors.lastname: Zavialov
authors.forename: Wen
authors.initials: W
authors.lastname: Li
authors.forename: Jayati
authors.initials: J
authors.lastname: Sengupta
authors.forename: Mikel
authors.initials: M
authors.lastname: Valle
authors.forename: Richard P
authors.initials: RP
authors.lastname: Gursky
authors.forename: Måns
authors.initials: M
authors.lastname: Ehrenberg
authors.forename: Joachim
authors.initials: J
authors.lastname: Frank
mesh_terms: D020285:Cryoelectron Microscopy / Q000379:methods; D007091:Image Processing, Computer-Assisted; D008958:Models, Molecular; D008968:Molecular Conformation; D010443:Peptide Chain Termination, Translational; D020653:Peptide Elongation Factor G / Q000378:metabolism; D011487:Protein Conformation; D017433:Protein Structure, Secondary; D012333:RNA, Messenger / Q000737:chemistry / Q000648:ultrastructure*; D012269:Ribosomal Proteins / Q000378:metabolism
chemical_list: D020653:Peptide Elongation Factor G; D012333:RNA, Messenger; D012269:Ribosomal Proteins; C087267:ribosome releasing factor