scholarly journals Relationship between elongation factor 1- and elongation factor 2-dependent guanosine triphosphatase activities of ribosomes. Inhibition of both activities by ricin

1975 ◽  
Vol 148 (3) ◽  
pp. 447-451 ◽  
Author(s):  
S Sperti ◽  
L Montanaro ◽  
A Mattioli ◽  
G Testoni
Keyword(s):  
Ribosomal Subunit ◽  
Elongation Factor ◽  
Elongation Factors ◽  
Toxic Protein ◽  
Elongation Factor 2 ◽  
Guanosine Triphosphatase ◽  
Elongation Factor 1 ◽  
Ricin A

The elongation factor 1- and elongation factor 2-dependent GTPase (guanosine triphosphatase) activities of ribosomes are inhibited by ricin, a toxic protein known to inactivate the 60S ribosomal subunit. It is suggested that also in eukaryotic ribosomes a “GTPase site’, located on the larger subunit, is common to the two elongation factors.

scholarly journals Peptide elongation in rat kidney after cadmium administration

1980 ◽  
Vol 190 (3) ◽  
pp. 791-797 ◽  
Author(s):  
M J Kuliszewski ◽  
D M Nicholls
Keyword(s):  
Rat Kidney ◽  
Gel Filtration ◽  
Elongation Factor ◽  
Peptide Bond ◽  
Renal Tissue ◽  
Elongation Factors ◽  
Elongation Factor 2 ◽  
Peptide Elongation ◽  
Elongation Factor 1 ◽  
Trna Binding

Rats received two injections (each 2.6 mg/kg body wt.) of CdCl2, and the kidneys were removed 24 h later. Postmicrosomal supernatant fractions of the homogenized kidneys were used as a source of elongation factors 1 and 2 in assays for [14C]phenylalanyl-tRNA binding to ribosomes and for peptide-bond synthesis. After purification of these preparations by precipitation with (NH4)2SO4 and gel filtration on Sephadex G-200 and G-100, elongation factor 1 activity was significantly increased. A significant increase in the activity of purified elongation factor 2 was also found. The results are discussed in relation to the reported effects of CdCl2 and of HgCl2 on renal tissue.

scholarly journals The mode of action of Shiga toxin on peptide elongation of eukaryotic protein synthesis

1987 ◽  
Vol 244 (2) ◽  
pp. 287-294 ◽  
Author(s):  
T G Obrig ◽  
T P Moran ◽  
J E Brown
Keyword(s):  
Protein Synthesis ◽  
Complex Formation ◽  
Shiga Toxin ◽  
Mode Of Action ◽  
Elongation Factor ◽  
Shigella Dysenteriae ◽  
Gtpase Activity ◽  
Elongation Factor 2 ◽  
Peptide Elongation ◽  
Elongation Factor 1

The effect of Shiga toxin, from Shigella dysenteriae 1, on the component reactions of peptide elongation were investigated. Enzymic binding of [3H]phenylalanine-tRNA to reticulocyte ribosomes was inhibited by 50% at 7 nM toxin. Elongation factor 1 (eEF-1)-dependent GTPase activity was also inhibited. Both reactions were not restored by addition of excess eEF-1 protein. In contrast, toxin concentrations of 200 nM were required to inhibit by 50% the elongation factor 2 (eEF-2)-dependent translocation of aminoacyl-tRNA on ribosomes. Addition of excess eEF-2 restored translocation activity. The eEF-2-dependent GTPase activity was unaffected at toxin concentrations below 100 nM, and Shiga-toxin concentrations of up to 1,000 nM did not affect either GTP.eEF-2.ribosome complex-formation or peptidyltransferase activity. Thus Shiga toxin closely resembles alpha-sarcin in action, both being primary inhibitors of eEF-1-dependent reactions. In contrast, the 60 S ribosome inactivators ricin and phytolaccin are primary inhibitors of eEF-2-dependent reactions of peptide elongation.

scholarly journals Integrity of the P-site is probed during maturation of the 60S ribosomal subunit

2012 ◽  
Vol 197 (6) ◽  
pp. 747-759 ◽  
Author(s):  
Cyril Bussiere ◽  
Yaser Hashem ◽  
Sucheta Arora ◽  
Joachim Frank ◽  
Arlen W. Johnson
Keyword(s):  
Molecular Dynamics ◽  
Molecular Dynamics Simulations ◽  
Ribonucleic Acid ◽  
Ribosomal Subunit ◽  
Elongation Factor ◽  
Molecular Signaling ◽  
Conformation Change ◽  
Guanosine Triphosphatase ◽  
Dynamics Simulations ◽  
Late Maturation

Eukaryotic ribosomes are preassembled in the nucleus and mature in the cytoplasm. Release of the antiassociation factor Tif6 by the translocase-like guanosine triphosphatase Efl1 is a critical late maturation step. In this paper, we show that a loop of Rpl10 that embraces the P-site transfer ribonucleic acid was required for release of Tif6, 90 Å away. Mutations in this P-site loop blocked 60S maturation but were suppressed by mutations in Tif6 or Efl1. Molecular dynamics simulations of the mutant Efl1 proteins suggest that they promote a conformation change in Efl1 equivalent to changes that elongation factor G and eEF2 undergo during translocation. These results identify molecular signaling from the P-site to Tif6 via Efl1, suggesting that the integrity of the P-site is interrogated during maturation. We propose that Efl1 promotes a functional check of the integrity of the 60S subunit before its first round of translation.

scholarly journals Molecular characterization and phylogenetic analyses of Lophodermella needle pathogens (Rhytismataceae) on Pinus species in the USA and Europe

PeerJ ◽  
2021 ◽  
Vol 9 ◽  
pp. e11435
Author(s):  
Jessa P. Ata ◽  
Kelly S. Burns ◽  
Suzanne Marchetti ◽  
Isabel A. Munck ◽  
Ludwig Beenken ◽  
...  
Keyword(s):  
Phylogenetic Analyses ◽  
Ribosomal Subunit ◽  
Elongation Factor ◽  
Translation Elongation ◽  
Phenotypic Characters ◽  
Elongation Factor 1 Alpha ◽  
The Usa ◽  
Phylogenetic Resolution ◽  
Elongation Factor 1

Increasing prevalence of conifer needle pathogens globally have prompted further studies on pathogen identification and a better understanding of phylogenetic relationships among needle pathogens. Several Lophodermella species can be aggressive pathogens causing needle cast in natural pine forests in the USA and Europe. However, their relationships with other Rhytismataceae species have historically been based on similarities of only limited phenotypic characters. Currently, no molecular studies have been completed to elucidate their relationships with other Lophodermella needle pathogens. This study collected and sequenced three gene loci, namely: internal transcribed spacer, large ribosomal subunit, and translation elongation factor 1-alpha, from five Lophodermella needle pathogens from North America (L. arcuata, L. concolor, L. montivaga) and Europe (L. conjuncta and L. sulcigena) to distinguish phylogeny within Rhytismatacaeae, including Lophophacidium dooksii. Phylogenetic analyses of the three loci revealed that all but L. conjuncta that were sampled in this study consistently clustered in a well-supported clade within Rhytismataceae. The multi-gene phylogeny also confirmed consistent nesting of L. dooksii, a needle pathogen of Pinus strobus, within the clade. Potential synapomorphic characters such as ascomata position and ascospore shape for the distinct clade were also explored. Further, a rhytismataceous species on P. flexilis that was morphologically identified as L. arcuata was found to be unique based on the sequences at the three loci. This study suggests a potential wider range of host species within the genus and the need for genetic characterization of other Lophodermella and Lophophacidium species to provide a higher phylogenetic resolution.

scholarly journals Effect of α-sarcin and ribosome-inactivating proteins on the interaction of elongation factors with ribosomes

1989 ◽  
Vol 257 (3) ◽  
pp. 723-727 ◽  
Author(s):  
M Brigotti ◽  
F Rambelli ◽  
M Zamboni ◽  
L Montanaro ◽  
S Sperti
Keyword(s):  
Higher Plants ◽  
Ricinus Communis ◽  
Ribosomal Subunit ◽  
Elongation Factor ◽  
Artemia Salina ◽  
Elongation Factors ◽  
Ribosome Inactivating Proteins ◽  
Rabbit Reticulocyte Lysate System ◽  
Reticulocyte Lysate ◽  
Comparable Activity

alpha-Sarcin from Aspergillus giganteus and the ribosome-inactivating proteins (RIPs) from higher plants inactivate the 60 S ribosomal subunit. The former is an RNAase, whereas RIPs are N-glycosidases. The site of cleavage of RNA and that of N-glycosidic depurinization are at one nucleotide distance in 28 S rRNA [Endo & Tsurugi (1987) J. Biol. Chem. 262, 8128-8130]. The effect of alpha-sarcin and that of RIPs on the interaction of elongation factors with Artemia salina (brine shrimp) ribosomes have been investigated. alpha-Sarcin inhibits both the EF1 (elongation factor 1)-dependent binding of aminoacyl-tRNA and the GTP-dependent binding of EF2 (elongation factor 2) to ribosomes, whereas two of the RIPs tested, ricin from Ricinus communis (castor bean) and volkensin from Adenia volkensii (kilyambiti), inhibit only the latter reaction. EF2 protects ribosomes from inactivation by both alpha-sarcin and ricin. The EF1-binding site is affected only by alpha-sarcin. The sensitivity of this site to alpha-sarcin is increased by pretreatment of ribosomes with ricin. A. salina ribosomes were highly resistant to the third RIP tested, namely gelonin from Gelonium multiflorum. All four proteins tested have, however, a comparable activity on the rabbit reticulocyte-lysate system.

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 The Archaeal Elongation Factor EF-2 Induces the Release of aIF6 From 50S Ribosomal Subunit

2021 ◽  
Vol 12 ◽  
Author(s):  
Giada Lo Gullo ◽  
Maria Luisa De Santis ◽  
Alessandro Paiardini ◽  
Serena Rosignoli ◽  
Alice Romagnoli ◽  
...  
Keyword(s):  
Large Subunit ◽  
Ribosomal Subunit ◽  
Elongation Factor ◽  
Structural Data ◽  
Small Subunit ◽  
Large Ribosomal Subunit ◽  
Homologous Proteins ◽  
Gtp Hydrolysis ◽  
Elongation Factor 2 ◽  
Docking Protein

The translation factor IF6 is a protein of about 25 kDa shared by the Archaea and the Eukarya but absent in Bacteria. It acts as a ribosome anti-association factor that binds to the large subunit preventing the joining to the small subunit. It must be released from the large ribosomal subunit to permit its entry to the translation cycle. In Eukarya, this process occurs by the coordinated action of the GTPase Efl1 and the docking protein SBDS. Archaea do not possess a homolog of the former factor while they have a homolog of SBDS. In the past, we have determined the function and ribosomal localization of the archaeal (Sulfolobus solfataricus) IF6 homolog (aIF6) highlighting its similarity to the eukaryotic counterpart. Here, we analyzed the mechanism of aIF6 release from the large ribosomal subunit. We found that, similarly to the Eukarya, the detachment of aIF6 from the 50S subunit requires a GTPase activity which involves the archaeal elongation factor 2 (aEF-2). However, the release of aIF6 from the 50S subunits does not require the archaeal homolog of SBDS, being on the contrary inhibited by its presence. Molecular modeling, using published structural data of closely related homologous proteins, elucidated the mechanistic interplay between the aIF6, aSBDS, and aEF2 on the ribosome surface. The results suggest that a conformational rearrangement of aEF2, upon GTP hydrolysis, promotes aIF6 ejection. On the other hand, aSBDS and aEF2 share the same binding site, whose occupation by SBDS prevents aEF2 binding, thereby inhibiting aIF6 release.

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