title: Ribosome-induced changes in elongation factor Tu conformation control GTP hydrolysis.
abstract: In translation, elongation factor Tu (EF-Tu) molecules deliver aminoacyl-tRNAs to the mRNA-programmed ribosome. The GTPase activity of EF-Tu is triggered by ribosome-induced conformational changes of the factor that play a pivotal role in the selection of the cognate aminoacyl-tRNAs. We present a 6.7-A cryo-electron microscopy map of the aminoacyl-tRNA x EF-Tu x GDP x kirromycin-bound Escherichia coli ribosome, together with an atomic model of the complex obtained through molecular dynamics flexible fitting. The model reveals the conformational changes in the conserved GTPase switch regions of EF-Tu that trigger hydrolysis of GTP, along with key interactions, including those between the sarcin-ricin loop and the P loop of EF-Tu, and between the effector loop of EF-Tu and a conserved region of the 16S rRNA. Our data suggest that GTP hydrolysis on EF-Tu is controlled through a hydrophobic gate mechanism.
authors.affiliation: Beckman Institute, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA.
authors.forename: Elizabeth
authors.initials: E
authors.lastname: Villa
authors.forename: Jayati
authors.initials: J
authors.lastname: Sengupta
authors.forename: Leonardo G
authors.initials: LG
authors.lastname: Trabuco
authors.forename: Jamie
authors.initials: J
authors.lastname: LeBarron
authors.forename: William T
authors.initials: WT
authors.lastname: Baxter
authors.forename: Tanvir R
authors.initials: TR
authors.lastname: Shaikh
authors.forename: Robert A
authors.initials: RA
authors.lastname: Grassucci
authors.forename: Poul
authors.initials: P
authors.lastname: Nissen
authors.forename: Måns
authors.initials: M
authors.lastname: Ehrenberg
authors.forename: Klaus
authors.initials: K
authors.lastname: Schulten
authors.forename: Joachim
authors.initials: J
authors.lastname: Frank
mesh_terms: D020285:Cryoelectron Microscopy; D004789:Enzyme Activation; D004926:Escherichia coli / Q000201:enzymology / Q000378:metabolism*; D029968:Escherichia coli Proteins / Q000378:metabolism; D006160:Guanosine Triphosphate / Q000378:metabolism*; D006639:Histidine / Q000378:metabolism; D006868:Hydrolysis; D057927:Hydrophobic and Hydrophilic Interactions; D008958:Models, Molecular; D010444:Peptide Elongation Factor Tu / Q000737:chemistry* / Q000648:ultrastructure; D017433:Protein Structure, Secondary; D012343:RNA, Transfer / Q000378:metabolism; D012269:Ribosomal Proteins / Q000378:metabolism; D012270:Ribosomes / Q000737:chemistry / Q000378:metabolism* / Q000648:ultrastructure; D015398:Signal Transduction
chemical_list: D029968:Escherichia coli Proteins; D012269:Ribosomal Proteins; C512844:rplL protein, E coli; D006639:Histidine; D006160:Guanosine Triphosphate; D012343:RNA, Transfer; D010444:Peptide Elongation Factor Tu