scholarly journals Elongation Factor G Bound to the Ribosome in an Intermediate State of Translocation

Science ◽  
2013 ◽  
Vol 340 (6140) ◽  
pp. 1235490 ◽  
Author(s):  
David S. Tourigny ◽  
Israel S. Fernández ◽  
Ann C. Kelley ◽  
V. Ramakrishnan
Keyword(s):  
Intermediate State ◽  
Messenger Rna ◽  
Structural Changes ◽  
Thermus Thermophilus ◽  
Elongation Factor ◽  
Chain Elongation ◽  
Protein Chain ◽  
Elongation Factor G ◽  
Guanosine Triphosphatase ◽  
Factor G

A key step of translation by the ribosome is translocation, which involves the movement of messenger RNA (mRNA) and transfer RNA (tRNA) with respect to the ribosome. This allows a new round of protein chain elongation by placing the next mRNA codon in the A site of the 30S subunit. Translocation proceeds through an intermediate state in which the acceptor ends of the tRNAs have moved with respect to the 50S subunit but not the 30S subunit, to form hybrid states. The guanosine triphosphatase (GTPase) elongation factor G (EF-G) catalyzes the subsequent movement of mRNA and tRNA with respect to the 30S subunit. Here, we present a crystal structure at 3 angstrom resolution of the Thermus thermophilus ribosome with a tRNA in the hybrid P/E state bound to EF-G with a GTP analog. The structure provides insights into structural changes that facilitate translocation and suggests a common GTPase mechanism for EF-G and elongation factor Tu.

scholarly journals Elongation factor G initiates translocation through a power stroke

2016 ◽  
Vol 113 (27) ◽  
pp. 7515-7520 ◽  
Author(s):  
Chunlai Chen ◽  
Xiaonan Cui ◽  
John F. Beausang ◽  
Haibo Zhang ◽  
Ian Farrell ◽  
...  
Keyword(s):  
Single Molecule ◽  
Messenger Rna ◽  
Elongation Factor ◽  
Power Stroke ◽  
Elongation Factor G ◽  
Gtp Hydrolysis ◽  
Guanosine Triphosphatase ◽  
Prokaryotic Protein ◽  
Domain Iii ◽  
Factor G

During the translocation step of prokaryotic protein synthesis, elongation factor G (EF-G), a guanosine triphosphatase (GTPase), binds to the ribosomal PRE-translocation (PRE) complex and facilitates movement of transfer RNAs (tRNAs) and messenger RNA (mRNA) by one codon. Energy liberated by EF-G’s GTPase activity is necessary for EF-G to catalyze rapid and precise translocation. Whether this energy is used mainly to drive movements of the tRNAs and mRNA or to foster EF-G dissociation from the ribosome after translocation has been a long-lasting debate. Free EF-G, not bound to the ribosome, adopts quite different structures in its GTP and GDP forms. Structures of EF-G on the ribosome have been visualized at various intermediate steps along the translocation pathway, using antibiotics and nonhydolyzable GTP analogs to block translocation and to prolong the dwell time of EF-G on the ribosome. However, the structural dynamics of EF-G bound to the ribosome have not yet been described during normal, uninhibited translocation. Here, we report the rotational motions of EF-G domains during normal translocation detected by single-molecule polarized total internal reflection fluorescence (polTIRF) microscopy. Our study shows that EF-G has a small (∼10°) global rotational motion relative to the ribosome after GTP hydrolysis that exerts a force to unlock the ribosome. This is followed by a larger rotation within domain III of EF-G before its dissociation from the ribosome.

scholarly journals Control of Ribosomal Subunit Rotation by Elongation Factor G

Science ◽  
2013 ◽  
Vol 340 (6140) ◽  
pp. 1235970 ◽  
Author(s):  
Arto Pulk ◽  
Jamie H. D. Cate
Keyword(s):  
Messenger Rna ◽  
Ribosomal Subunit ◽  
Elongation Factor ◽  
Peptide Bond ◽  
Elongation Factor G ◽  
Before And After ◽  
Switch Regions ◽  
Subunit Rotation ◽  
Guanosine Triphosphatase ◽  
Factor G

Protein synthesis by the ribosome requires the translocation of transfer RNAs and messenger RNA by one codon after each peptide bond is formed, a reaction that requires ribosomal subunit rotation and is catalyzed by the guanosine triphosphatase (GTPase) elongation factor G (EF-G). We determined 3 angstrom resolution x-ray crystal structures of EF-G complexed with a nonhydrolyzable guanosine 5′-triphosphate (GTP) analog and bound to the Escherichia coli ribosome in different states of ribosomal subunit rotation. The structures reveal that EF-G binding to the ribosome stabilizes switch regions in the GTPase active site, resulting in a compact EF-G conformation that favors an intermediate state of ribosomal subunit rotation. These structures suggest that EF-G controls the translocation reaction by cycles of conformational rigidity and relaxation before and after GTP hydrolysis.

scholarly journals Activation of GTP hydrolysis in mRNA-tRNA translocation by elongation factor G

2015 ◽  
Vol 1 (4) ◽  
pp. e1500169 ◽  
Author(s):  
Wen Li ◽  
Zheng Liu ◽  
Ravi Kiran Koripella ◽  
Robert Langlois ◽  
Suparna Sanyal ◽  
...  
Keyword(s):  
Elongation Factor ◽  
Elongation Factor G ◽  
Direct Role ◽  
Gtp Hydrolysis ◽  
Ribosomal Subunits ◽  
Trna Translocation ◽  
Gtpase Activation ◽  
Guanosine Triphosphatase ◽  
Factor G

During protein synthesis, elongation of the polypeptide chain by each amino acid is followed by a translocation step in which mRNA and transfer RNA (tRNA) are advanced by one codon. This crucial step is catalyzed by elongation factor G (EF-G), a guanosine triphosphatase (GTPase), and accompanied by a rotation between the two ribosomal subunits. A mutant of EF-G, H91A, renders the factor impaired in guanosine triphosphate (GTP) hydrolysis and thereby stabilizes it on the ribosome. We use cryogenic electron microscopy (cryo-EM) at near-atomic resolution to investigate two complexes formed by EF-G H91A in its GTP state with the ribosome, distinguished by the presence or absence of the intersubunit rotation. Comparison of these two structures argues in favor of a direct role of the conserved histidine in the switch II loop of EF-G in GTPase activation, and explains why GTP hydrolysis cannot proceed with EF-G bound to the unrotated form of the ribosome.

scholarly journals Effect of propan-2-ol on enzymic and structural properties of elongation factor G

1989 ◽  
Vol 261 (3) ◽  
pp. 725-731 ◽  
Author(s):  
M Masullo ◽  
G Parlato ◽  
E De Vendittis ◽  
V Bocchini
Keyword(s):  
Conformational Changes ◽  
Structural Changes ◽  
Elongation Factor ◽  
Elongation Factor G ◽  
Fluorescence Measurements ◽  
Different Temperatures ◽  
Number Of Binding Sites ◽  
Kinetics Of ◽  
Factor G

Elongation factor G (EF-G) can support a GTPase activity in vitro even in the absence of ribosomes when propan-2-ol is present [GTPasep; De Vendittis, Masullo & Bocchini (1986) J. Biol. Chem. 261, 4445-4450]. In the present work the GTPasep activity of EF-G was further studied by investigating (i) the effect of ionic environment on GTPasep and (ii) the influence of propan-2-ol on the molecular structure of EF-G as determined by fluorescence and c.d. measurements. In the presence of 1-300 mM univalent cations (M+) alone, no detectable GTPasep activity was measured; however, in the presence of 1 mM-Mg2+ a considerable stimulation was observed at 40 mM-Li+ or 75 mM-NH4+. Among bivalent cations (M2+), 1 mM-Sr2+, 2-5 mM-Ca2+ and 1 mM-Ba2+ were the most effective, but, in the presence of 75 mM-NH4+, Mg2+ and Mn2+ became the most efficient, whereas the stimulation by other M2+ species was considerably decreased. C.d. measurements showed that the alcohol increased the mean molar residue ellipticity of EF-G at 285 nm, but not at 220 nm. As estimated from fluorescence measurements, in the presence of 20% (v/v) propan-2-ol the value of the dissociation constant of the complex formed between EF-G and 8-anilino-1-naphthalene-sulphonate decreased from 8 to 5 microM; similarly, the number of binding sites on EF-G for the fluorescent probe decreased from 13 to 6. Finally, the alcohol enhanced the quenching of the intrinsic fluorescence of EF-G caused by either acrylamide or KI. The data support the hypothesis that propan-2-ol induces moderate conformational changes of EF-G that make the catalytic centre accessible to the substrate even in the absence of ribosomes. Kinetics of GTPasep studied at different temperatures did not reveal additional structural changes of EF-G occurring with time or temperature.

Crystallographic study of elongation factor G from Thermus thermophilus HB8

1983 ◽  
Vol 168 (2) ◽  
pp. 449-450 ◽  
Author(s):  
Yu.N. Chirgadze ◽  
S.V. Nikonov ◽  
E.V. Brazhnikov ◽  
M.B. Garber ◽  
L.S. Reshetnikova
Keyword(s):  
Thermus Thermophilus ◽  
Elongation Factor ◽  
Elongation Factor G ◽  
Thermus Thermophilus Hb8 ◽  
Crystallographic Study ◽  
Factor G

scholarly journals Three-dimensional structure of the ribosomal translocase: elongation factor G from Thermus thermophilus.

1994 ◽  
Vol 13 (16) ◽  
pp. 3669-3677 ◽  
Author(s):  
A. AEvarsson ◽  
E. Brazhnikov ◽  
M. Garber ◽  
J. Zheltonosova ◽  
Y. Chirgadze ◽  
...  
Keyword(s):  
Thermus Thermophilus ◽  
Three Dimensional ◽  
Elongation Factor ◽  
Dimensional Structure ◽  
Elongation Factor G ◽  
Three Dimensional Structure ◽  
Factor G
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