Role of Elongation Factors in Steering the Ribosomal Elongation Cycle

Nierhaus, Knud H.; Triana, Francisco

doi:10.1007/978-1-4615-2894-4_3

Cited by 2 publications

(3 citation statements)

References 30 publications

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“…This suggests that the binding of a signal-transducing molecule (such as a protein) may be restricted to a certain stage of the ribosomal cycle and that the binding of this transducing component may be abolished in arrested ribosomes. Examples of proteins that bind to the S/R loop in a ribosomal cycle-dependent manner are the elongation factors EF-Tu/EF-1 and EF-G/EF-2 (31,32,53). ADPribosylation of EF-2 inhibited the activation of SAPK/JNK1 by ricin A chain or ␣-sarcin (Fig.…”

Section: Discussionmentioning

confidence: 99%

“…The immunoprecipitates were washed once with lysis buffer, once with a solution consisting of 100 mM Tris-HCl (pH 7.6), 500 mM LiCl, 1 mM DTT, and 0.1% Triton X-100, and once with a buffer containing 20 mM morpholinepropanesulfonic acid (MOPS; pH 7.2), 10 mM MgCl 2 , 2 mM EGTA, 1 mM DTT, and 0.1% Triton X-100. For the kinase reaction, the immunoprecipitates were incubated with 1 g of either glutathione S-transferase (GST)-Elk1 (38) or GST-cJun (24) fusion proteins in the presence of 10 mM MOPS (pH 7.2), 20 mM MgCl 2 , 1 mM EGTA, 0.5 mM DTT, 0.05% Triton X-100 and 1 Ci [␥- 32 P]ATP for 20 min at 30°C. After the reactions were stopped by adding 10 l of 4ϫ sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) loading buffer, the samples were resolved by SDS-13% PAGE.…”

Section: Methodsmentioning

confidence: 99%

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Ribotoxic Stress Response: Activation of the Stress-Activated Protein Kinase JNK1 by Inhibitors of the Peptidyl Transferase Reaction and by Sequence-Specific RNA Damage to the α-Sarcin/Ricin Loop in the 28S rRNA

Iordanov

Pribnow

Magun

et al. 1997

Molecular and Cellular Biology

441

500

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Inhibition of protein synthesis per se does not potentiate the stress-activated protein kinases (SAPKs; also known as cJun NH 2 -terminal kinases [JNKs]). The protein synthesis inhibitor anisomycin, however, is a potent activator of SAPKs/JNKs. The mechanism of this activation is unknown. We provide evidence that in order to activate SAPK/JNK1, anisomycin requires ribosomes that are translationally active at the time of contact with the drug, suggesting a ribosomal origin of the anisomycin-induced signaling to SAPK/JNK1. In support of this notion, we have found that aminohexose pyrimidine nucleoside antibiotics, which bind to the same region in the 28S rRNA that is the target site for anisomycin, are also potent activators of SAPK/JNK1. Binding of an antibiotic to the 28S rRNA interferes with the functioning of the molecule by altering the structural interactions of critical regions. We hypothesized, therefore, that such alterations in the 28S rRNA may act as recognition signals to activate SAPK/JNK1. To test this hypothesis, we made use of two ribotoxic enzymes, ricin A chain and ␣-sarcin, both of which catalyze sequence-specific RNA damage in the 28S rRNA. Consistent with our hypothesis, ricin A chain and ␣-sarcin were strong agonists of SAPK/JNK1 and of its activator SEK1/MKK4 and induced the expression of the immediate-early genes c-fos and c-jun. As in the case of anisomycin, ribosomes that were active at the time of exposure to ricin A chain or ␣-sarcin were able to initiate signal transduction from the damaged 28S rRNA to SAPK/JNK1 while inactive ribosomes were not.The activity of the stress-activated protein kinases (SAPKs; also known as cJun NH 2 -terminal kinases [JNKs]) is stimulated in response to certain kinds of cellular stress, including exposure of cells to short-wavelength UV radiation (11, 19), alkylating DNA-damaging agents (27), the tumor promoters As 3ϩ (7) and palytoxin (23), hyperosmotic shock (16), proinflammatory cytokines (24), or withdrawal of a trophic factor (54). SAPKs/JNKs are members of the mitogen-activated protein kinase (MAPK) family of proline-directed serine/threonine protein kinases, which also includes the extracellular signalregulated kinases (ERKs) and the p38/RK/HOG1 kinase (for a review, see reference 51). Upon activation, SAPKs/ JNKs phosphorylate and activate transcription factors such as cJun (11), ATF-2 (17, 49), and Elk-1 (6, 52, 56), leading ultimately to the transcriptional activation of the immediate-early genes c-fos and c-jun (49, 56). The signal transduction cascades that lead to activation of SAPKs/JNKs and to subsequent gene induction are thought to be associated with stress responses that promote either cell recovery and survival after cellular damage (13,18,41) or, in some instances, apoptotic death (8, 54). The activity of SAPKs/JNKs is regulated through their phosphorylation on both threonine and tyrosine residues in the motif T‫ء‬PY‫ء‬ by the dual-specificity protein kinase SEK1/MKK4 (12,26,40). The protein kinase MEKK1 (25), in turn, activates SEK1/MK...

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Section: Discussionmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Ribotoxic Stress Response: Activation of the Stress-Activated Protein Kinase JNK1 by Inhibitors of the Peptidyl Transferase Reaction and by Sequence-Specific RNA Damage to the α-Sarcin/Ricin Loop in the 28S rRNA

Iordanov

Pribnow

Magun

et al. 1997

Molecular and Cellular Biology

441

500

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“…If the elongation factors trigger the allosteric transition via melting of the stem of the a-sarcin stem-loop structure, the stem structure should not be very stable, thus facilitating a melting and rejoining process. A systematic survey of the corresponding stem of ribosomes from all kingdoms has indeed shown that the structural lability of the stem is a second universally conserved feature of the a-sarcin stem-loop structure (Nierhaus and Triana, 1993).…”

Section: Outlook: Mechanism Of Action Of the Elongation Factorsmentioning

confidence: 99%

Solution of the ribosome riddle: how the ribosome selects the correct aminoacyl‐tRNA out of 41 similar contestants

Nierhaus

1993

Molecular Microbiology

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Three tRNA binding sites, the A, P and E sites, have been demonstrated on ribosomes of bacterial, archaebacterial and eukaryotic origin. In all these cases the first and the third site, the A and the E site, are allosterically coupled in the sense of a negative co-operativity. Therefore, the allosteric three-site model seems to be a generally valid description of the ribosomal elongation phase, where in a cycle of reactions the nascent peptide chain is prolonged by one amino acid. The molecular concept of the allosteric three-site model explains the astonishing ability of the ribosome to select the correct substrate out of a large number of very similar substrates, and it provides a framework within which the mechanisms of the elongation factors could be understood.

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Role of Elongation Factors in Steering the Ribosomal Elongation Cycle

Cited by 2 publications

References 30 publications

Ribotoxic Stress Response: Activation of the Stress-Activated Protein Kinase JNK1 by Inhibitors of the Peptidyl Transferase Reaction and by Sequence-Specific RNA Damage to the α-Sarcin/Ricin Loop in the 28S rRNA

Ribotoxic Stress Response: Activation of the Stress-Activated Protein Kinase JNK1 by Inhibitors of the Peptidyl Transferase Reaction and by Sequence-Specific RNA Damage to the α-Sarcin/Ricin Loop in the 28S rRNA

Solution of the ribosome riddle: how the ribosome selects the correct aminoacyl‐tRNA out of 41 similar contestants

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