201
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Ghosh A, Komar AA. Eukaryote-specific extensions in ribosomal proteins of the small subunit: Structure and function. ACTA ACUST UNITED AC 2015; 3:e999576. [PMID: 26779416 DOI: 10.1080/21690731.2014.999576] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2014] [Revised: 12/03/2014] [Accepted: 12/12/2014] [Indexed: 01/05/2023]
Abstract
High-resolution structures of yeast ribosomes have improved our understanding of the architecture and organization of eukaryotic rRNA and proteins, as well as eukaryote-specific extensions present in some conserved ribosomal proteins. Despite this progress, assignment of specific functions to individual proteins and/or eukaryote-specific protein extensions remains challenging. It has been suggested that eukaryote-specific extensions of conserved proteins from the small ribosomal subunit may facilitate eukaryote-specific reactions in the initiation phase of protein synthesis. This review summarizes emerging data describing the structural and functional significance of eukaryote-specific extensions of conserved small ribosomal subunit proteins, particularly their possible roles in recruitment and spatial organization of eukaryote-specific initiation factors.
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Affiliation(s)
- Arnab Ghosh
- Center for Gene Regulation in Health and Disease; Department of Biological, Geological and Environmental Sciences; Cleveland State University ; Cleveland, OH USA
| | - Anton A Komar
- Center for Gene Regulation in Health and Disease; Department of Biological, Geological and Environmental Sciences; Cleveland State University ; Cleveland, OH USA
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202
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Barbet-Massin E, Huang CT, Daebel V, Hsu STD, Reif B. Site-Specific Solid-State NMR Studies of “Trigger Factor” in Complex with the Large Ribosomal Subunit 50S. Angew Chem Int Ed Engl 2015; 54:4367-9. [DOI: 10.1002/anie.201409393] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2014] [Revised: 01/09/2015] [Indexed: 02/01/2023]
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203
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Graifer D, Karpova G. Roles of ribosomal proteins in the functioning of translational machinery of eukaryotes. Biochimie 2015; 109:1-17. [DOI: 10.1016/j.biochi.2014.11.016] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2014] [Accepted: 11/18/2014] [Indexed: 11/16/2022]
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204
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Skakauskas V, Katauskis P, Skvortsov A, Gray P. Toxin effect on protein biosynthesis in eukaryotic cells: a simple kinetic model. Math Biosci 2015; 261:83-90. [PMID: 25572165 DOI: 10.1016/j.mbs.2014.12.004] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2014] [Revised: 12/24/2014] [Accepted: 12/26/2014] [Indexed: 10/24/2022]
Abstract
A model for toxin inhibition of protein synthesis inside eukaryotic cells is presented. Mitigation of this effect by introduction of an antibody is also studied. Antibody and toxin (ricin) initially are delivered outside the cell. The model describes toxin internalization from the extracellular into the intracellular domain, its transport to the endoplasmic reticulum (ER) and the cleavage inside the ER into the RTA and RTB chains, the release of RTA into the cytosol, inactivation (depurination) of ribosomes, and the effect on translation. The model consists of a set of ODEs which are solved numerically. Numerical results are illustrated by figures and discussed.
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Affiliation(s)
- Vladas Skakauskas
- Faculty of Mathematics and Informatics, Vilnius University, Naugarduko 24, Vilnius 03225, Lithuania.
| | - Pranas Katauskis
- Faculty of Mathematics and Informatics, Vilnius University, Naugarduko 24, Vilnius 03225, Lithuania
| | - Alex Skvortsov
- Defence Science and Technology Organisation, 506 Lorimer st., Melbourne, VIC 3207, Australia
| | - Peter Gray
- Defence Science and Technology Organisation, 506 Lorimer st., Melbourne, VIC 3207, Australia
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205
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Kirchner S, Ignatova Z. Emerging roles of tRNA in adaptive translation, signalling dynamics and disease. Nat Rev Genet 2014; 16:98-112. [DOI: 10.1038/nrg3861] [Citation(s) in RCA: 355] [Impact Index Per Article: 35.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
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206
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Zur H, Tuller T. Exploiting hidden information interleaved in the redundancy of the genetic code without prior knowledge. ACTA ACUST UNITED AC 2014; 31:1161-8. [PMID: 25433697 DOI: 10.1093/bioinformatics/btu797] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2014] [Accepted: 11/25/2014] [Indexed: 11/13/2022]
Abstract
MOTIVATION Dozens of studies in recent years have demonstrated that codon usage encodes various aspects related to all stages of gene expression regulation. When relevant high-quality large-scale gene expression data are available, it is possible to statistically infer and model these signals, enabling analysing and engineering gene expression. However, when these data are not available, it is impossible to infer and validate such models. RESULTS In this current study, we suggest Chimera-an unsupervised computationally efficient approach for exploiting hidden high-dimensional information related to the way gene expression is encoded in the open reading frame (ORF), based solely on the genome of the analysed organism. One version of the approach, named Chimera Average Repetitive Substring (ChimeraARS), estimates the adaptability of an ORF to the intracellular gene expression machinery of a genome (host), by computing its tendency to include long substrings that appear in its coding sequences; the second version, named ChimeraMap, engineers the codons of a protein such that it will include long substrings of codons that appear in the host coding sequences, improving its adaptation to a new host's gene expression machinery. We demonstrate the applicability of the new approach for analysing and engineering heterologous genes and for analysing endogenous genes. Specifically, focusing on Escherichia coli, we show that it can exploit information that cannot be detected by conventional approaches (e.g. the CAI-Codon Adaptation Index), which only consider single codon distributions; for example, we report correlations of up to 0.67 for the ChimeraARS measure with heterologous gene expression, when the CAI yielded no correlation. AVAILABILITY AND IMPLEMENTATION For non-commercial purposes, the code of the Chimera approach can be downloaded from http://www.cs.tau.ac.il/∼tamirtul/Chimera/download.htm. CONTACT tamirtul@post.tau.ac.il SUPPLEMENTARY INFORMATION Supplementary data are available at Bioinformatics online.
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Affiliation(s)
- Hadas Zur
- Department of Biomedical Engineering, The Engineering Faculty, Blavatnik School of Computer Science, Faculty of Exact Sciences and Sagol School of Neuroscience, Tel Aviv University, Tel-Aviv 69978, Israel Department of Biomedical Engineering, The Engineering Faculty, Blavatnik School of Computer Science, Faculty of Exact Sciences and Sagol School of Neuroscience, Tel Aviv University, Tel-Aviv 69978, Israel
| | - Tamir Tuller
- Department of Biomedical Engineering, The Engineering Faculty, Blavatnik School of Computer Science, Faculty of Exact Sciences and Sagol School of Neuroscience, Tel Aviv University, Tel-Aviv 69978, Israel Department of Biomedical Engineering, The Engineering Faculty, Blavatnik School of Computer Science, Faculty of Exact Sciences and Sagol School of Neuroscience, Tel Aviv University, Tel-Aviv 69978, Israel
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207
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McPherson A, Cudney B. Optimization of crystallization conditions for biological macromolecules. Acta Crystallogr F Struct Biol Commun 2014; 70:1445-67. [PMID: 25372810 PMCID: PMC4231845 DOI: 10.1107/s2053230x14019670] [Citation(s) in RCA: 70] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2014] [Accepted: 08/31/2014] [Indexed: 11/11/2022] Open
Abstract
For the successful X-ray structure determination of macromolecules, it is first necessary to identify, usually by matrix screening, conditions that yield some sort of crystals. Initial crystals are frequently microcrystals or clusters, and often have unfavorable morphologies or yield poor diffraction intensities. It is therefore generally necessary to improve upon these initial conditions in order to obtain better crystals of sufficient quality for X-ray data collection. Even when the initial samples are suitable, often marginally, refinement of conditions is recommended in order to obtain the highest quality crystals that can be grown. The quality of an X-ray structure determination is directly correlated with the size and the perfection of the crystalline samples; thus, refinement of conditions should always be a primary component of crystal growth. The improvement process is referred to as optimization, and it entails sequential, incremental changes in the chemical parameters that influence crystallization, such as pH, ionic strength and precipitant concentration, as well as physical parameters such as temperature, sample volume and overall methodology. It also includes the application of some unique procedures and approaches, and the addition of novel components such as detergents, ligands or other small molecules that may enhance nucleation or crystal development. Here, an attempt is made to provide guidance on how optimization might best be applied to crystal-growth problems, and what parameters and factors might most profitably be explored to accelerate and achieve success.
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Affiliation(s)
- Alexander McPherson
- Department of Molecular Biology and Biochemistry, University of California, Irvine, Irvine, CA 92697, USA
| | - Bob Cudney
- Hampton Research, 34 Journey, Aliso Viejo, CA 92656-3317, USA
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208
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Feng Y, Song X, Lin J, Xuan J, Cui Q, Wang J. Structure determination of archaea-specific ribosomal protein L46a reveals a novel protein fold. Biochem Biophys Res Commun 2014; 450:67-72. [PMID: 24875358 DOI: 10.1016/j.bbrc.2014.05.077] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2014] [Accepted: 05/16/2014] [Indexed: 01/21/2023]
Abstract
Three archaea-specific ribosomal proteins recently identified show no sequence homology with other known proteins. Here we determined the structure of L46a, the most conserved one among the three proteins, from Sulfolobus solfataricus P2 using NMR spectroscopy. The structure presents a twisted β-sheet formed by the N-terminal part and two helices at the C-terminus. The L46a structure has a positively charged surface which is conserved in the L46a protein family and is the potential rRNA-binding site. Searching homologous structures in Protein Data Bank revealed that the structure of L46a represents a novel protein fold. The backbone dynamics identified by NMR relaxation experiments reveal significant flexibility at the rRNA binding surface. The potential position of L46a on the ribosome was proposed by fitting the structure into a previous electron microscopy map of the ribosomal 50S subunit, which indicated that L46a contacts to domain I of 23S rRNA near a multifunctional ribosomal protein L7ae.
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Affiliation(s)
- Yingang Feng
- Shandong Provincial Key Laboratory of Energy Genetics, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao, Shandong 266101, China.
| | - Xiaxia Song
- Department of Biological Science and Engineering, School of Chemical and Biological Engineering, University of Science and Technology Beijing, Beijing 100083, China
| | - Jinzhong Lin
- National Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China
| | - Jinsong Xuan
- Department of Biological Science and Engineering, School of Chemical and Biological Engineering, University of Science and Technology Beijing, Beijing 100083, China
| | - Qiu Cui
- Shandong Provincial Key Laboratory of Energy Genetics, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao, Shandong 266101, China
| | - Jinfeng Wang
- National Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China
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209
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Hong M, Kim H, Kim I. Ribosomal protein L19 overexpression activates the unfolded protein response and sensitizes MCF7 breast cancer cells to endoplasmic reticulum stress-induced cell death. Biochem Biophys Res Commun 2014; 450:673-8. [PMID: 24950402 DOI: 10.1016/j.bbrc.2014.06.036] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2014] [Accepted: 06/07/2014] [Indexed: 02/02/2023]
Abstract
Although first identified for their roles in protein synthesis, certain ribosomal proteins exert pleiotropic physiological functions in the cell. Ribosomal protein L19 is overexpressed in breast cancer cells by amplification and copy number variation. In this study, we examined the novel pro-apoptotic role of ribosomal protein L19 in the breast cancer cell line MCF7. Overexpression of RPL19 sensitized MCF7 cells to endoplasmic reticulum stress-induced cell death. RPL19 overexpression itself was not cytotoxic; however, cell death induction was enhanced when RPL19 overexpressing cells were incubated with endoplasmic reticulum stress-inducing agents, and this sensitizing effect was specific to MCF7 cells. Examination of the cell signaling pathways that mediate the unfolded protein response (UPR) revealed that overexpression of RPL19 induced pre-activation of the UPR, including phosphorylation of pERK-like ER kinase (PERK), phosphorylation of eukaryotic translation initiation factor 2 alpha (eIF2α), and activation of p38 MAPK-associated stress signaling. Our findings suggest that upregulation of RPL19 induces ER stress, resulting in increased sensitivity to ER stress and enhanced cell death in MCF7 breast cancer cells.
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Affiliation(s)
- Mina Hong
- ASAN Institute for Life Sciences, ASAN Medical Center, Seoul, Republic of Korea
| | - HyungRyong Kim
- Department of Dental Pharmacology, School of Dentistry, Wonkwang University, Iksan, Chonbuk, Republic of Korea.
| | - Inki Kim
- ASAN Institute for Life Sciences, ASAN Medical Center, Seoul, Republic of Korea; Department of Medicine, University of Ulsan College of Medicine, Seoul, Republic of Korea.
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210
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Asano K. Why is start codon selection so precise in eukaryotes? ACTA ACUST UNITED AC 2014; 2:e28387. [PMID: 26779403 PMCID: PMC4705826 DOI: 10.4161/trla.28387] [Citation(s) in RCA: 51] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2013] [Revised: 02/14/2014] [Accepted: 02/27/2014] [Indexed: 12/22/2022]
Abstract
Translation generally initiates with the AUG codon. While initiation at GUG and UUG is permitted in prokaryotes (Archaea and Bacteria), cases of CUG initiation were recently reported in human cells. The varying stringency in translation initiation between eukaryotic and prokaryotic domains largely stems from a fundamental problem for the ribosome in recognizing a codon at the peptidyl-tRNA binding site. Initiation factors specific to each domain of life evolved to confer stringent initiation by the ribosome. The mechanistic basis for high accuracy in eukaryotic initiation is described based on recent findings concerning the role of the multifactor complex (MFC) in this process. Also discussed are whether non-AUG initiation plays any role in translational control and whether start codon accuracy is regulated in eukaryotes.
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Affiliation(s)
- Katsura Asano
- Molecular Cellular and Developmental Biology Program; Division of Biology; Kansas State University; Manhattan, KS USA
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211
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NMR contour maps as a new parameter of carboxyl’s OH groups in amino acids recognition: A reason of tRNA–amino acid conjugation. Chem Phys 2014. [DOI: 10.1016/j.chemphys.2014.01.017] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/07/2022]
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212
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Mao Y, Liu H, Liu Y, Tao S. Deciphering the rules by which dynamics of mRNA secondary structure affect translation efficiency in Saccharomyces cerevisiae. Nucleic Acids Res 2014; 42:4813-22. [PMID: 24561808 PMCID: PMC4005662 DOI: 10.1093/nar/gku159] [Citation(s) in RCA: 57] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
Messenger RNA (mRNA) secondary structure decreases the elongation rate, as ribosomes must unwind every structure they encounter during translation. Therefore, the strength of mRNA secondary structure is assumed to be reduced in highly translated mRNAs. However, previous studies in vitro reported a positive correlation between mRNA folding strength and protein abundance. The counterintuitive finding suggests that mRNA secondary structure affects translation efficiency in an undetermined manner. Here, we analyzed the folding behavior of mRNA during translation and its effect on translation efficiency. We simulated translation process based on a novel computational model, taking into account the interactions among ribosomes, codon usage and mRNA secondary structures. We showed that mRNA secondary structure shortens ribosomal distance through the dynamics of folding strength. Notably, when adjacent ribosomes are close, mRNA secondary structures between them disappear, and codon usage determines the elongation rate. More importantly, our results showed that the combined effect of mRNA secondary structure and codon usage in highly translated mRNAs causes a short ribosomal distance in structural regions, which in turn eliminates the structures during translation, leading to a high elongation rate. Together, these findings reveal how the dynamics of mRNA secondary structure coupling with codon usage affect translation efficiency.
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Affiliation(s)
- Yuanhui Mao
- College of Life Sciences and State Key Laboratory of Crop Stress Biology in Arid Areas, Northwest A&F University, Yangling, Shaanxi 712100, China, Bioinformatics Center, Northwest A&F University, Yangling, Shaanxi 712100, China and College of Enology, Northwest A&F University, Yangling, Shaanxi 712100, China
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213
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An examination of the inhibitory effects of three antibiotics in combination on ribosome biosynthesis in Staphylococcus aureus. Arch Microbiol 2014; 196:249-60. [DOI: 10.1007/s00203-014-0963-5] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2014] [Revised: 01/30/2014] [Accepted: 02/05/2014] [Indexed: 10/25/2022]
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214
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Mavridis I, Kythreoti G, Koltsida K, Vourloumis D. Rigid spiroethers targeting the decoding center of the bacterial ribosome. Bioorg Med Chem 2014; 22:1329-41. [PMID: 24457095 DOI: 10.1016/j.bmc.2013.12.068] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2013] [Revised: 12/30/2013] [Accepted: 12/30/2013] [Indexed: 01/21/2023]
Abstract
Continuing our efforts towards understanding the principles governing ribosomal recognition and function, we have synthesized and evaluated a series of diversely functionalized 5,6-, 6,6- and 7,6-spiroethers. These compounds successfully mimic natural aminoglycosides regarding their binding to the decoding center of the bacterial ribosome. Their potential to inhibit prokaryotic protein production in vitro along with their antibacterial potencies have also been examined.
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Affiliation(s)
- Ioannis Mavridis
- Chemical Biology Laboratories, National Center for Scientific Research 'Demokritos', Agia Paraskevi Attikis, GR-15310, Greece
| | - Georgia Kythreoti
- Chemical Biology Laboratories, National Center for Scientific Research 'Demokritos', Agia Paraskevi Attikis, GR-15310, Greece
| | - Konstantina Koltsida
- Chemical Biology Laboratories, National Center for Scientific Research 'Demokritos', Agia Paraskevi Attikis, GR-15310, Greece
| | - Dionisios Vourloumis
- Chemical Biology Laboratories, National Center for Scientific Research 'Demokritos', Agia Paraskevi Attikis, GR-15310, Greece.
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215
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The Mitochondrial Aminoacyl tRNA Synthetases: Genes and Syndromes. Int J Cell Biol 2014; 2014:787956. [PMID: 24639874 PMCID: PMC3932222 DOI: 10.1155/2014/787956] [Citation(s) in RCA: 103] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2013] [Accepted: 12/01/2013] [Indexed: 02/05/2023] Open
Abstract
Mitochondrial respiratory chain (RC) disorders are a group of genetically and clinically heterogeneous diseases. This is because protein components of the RC are encoded by both mitochondrial and nuclear genomes and are essential in all cells. In addition, the biogenesis and maintenance of mitochondria, including mitochondrial DNA (mtDNA) replication, transcription, and translation, require nuclear-encoded genes. In the past decade, a growing number of syndromes associated with dysfunction of mtDNA translation have been reported. This paper reviews the current knowledge of mutations affecting mitochondrial aminoacyl tRNAs synthetases and their role in the pathogenic mechanisms underlying the different clinical presentations.
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216
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The ABC-F protein EttA gates ribosome entry into the translation elongation cycle. Nat Struct Mol Biol 2014; 21:143-51. [PMID: 24389466 PMCID: PMC4101993 DOI: 10.1038/nsmb.2740] [Citation(s) in RCA: 86] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2013] [Accepted: 11/21/2013] [Indexed: 12/15/2022]
Abstract
ABC-F proteins have evaded functional characterization even though they comprise one of the most widely distributed branches of the ATP-binding cassette (ABC) superfamily. Herein, we demonstrate that YjjK, the most prevalent eubacterial ABC-F protein, gates ribosome entry into the translation elongation cycle through a nucleotide-dependent interaction sensitive to ATP/ADP ratio. Accordingly, we rename this protein Energy-dependent Translational Throttle A (EttA). We determined the crystal structure of Escherichia coli EttA and used it to design mutants for biochemical studies, including enzymological assays of the initial steps of protein synthesis. These studies suggest that EttA may regulate protein synthesis in energy-depleted cells, which have a low ATP/ADP ratio. Consistent with this inference, ΔettA cells exhibit a severe fitness defect in long-term stationary phase. These studies demonstrate that an ABC-F protein regulates protein synthesis via a novel mechanism sensitive to cellular energy status.
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217
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Structure of the ribosome with elongation factor G trapped in the pretranslocation state. Proc Natl Acad Sci U S A 2013; 110:20994-9. [PMID: 24324137 DOI: 10.1073/pnas.1311423110] [Citation(s) in RCA: 112] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
During protein synthesis, tRNAs and their associated mRNA codons move sequentially on the ribosome from the A (aminoacyl) site to the P (peptidyl) site to the E (exit) site in a process catalyzed by a universally conserved ribosome-dependent GTPase [elongation factor G (EF-G) in prokaryotes and elongation factor 2 (EF-2) in eukaryotes]. Although the high-resolution structure of EF-G bound to the posttranslocation ribosome has been determined, the pretranslocation conformation of the ribosome bound with EF-G and A-site tRNA has evaded visualization owing to the transient nature of this state. Here we use electron cryomicroscopy to determine the structure of the 70S ribosome with EF-G, which is trapped in the pretranslocation state using antibiotic viomycin. Comparison with the posttranslocation ribosome shows that the small subunit of the pretranslocation ribosome is rotated by ∼12° relative to the large subunit. Domain IV of EF-G is positioned in the cleft between the body and head of the small subunit outwardly of the A site and contacts the A-site tRNA. Our findings suggest a model in which domain IV of EF-G promotes the translocation of tRNA from the A to the P site as the small ribosome subunit spontaneously rotates back from the hybrid, rotated state into the nonrotated posttranslocation state.
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218
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Tomar SK, Artsimovitch I. NusG-Spt5 proteins-Universal tools for transcription modification and communication. Chem Rev 2013; 113:8604-19. [PMID: 23638618 PMCID: PMC4259564 DOI: 10.1021/cr400064k] [Citation(s) in RCA: 47] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Sushil Kumar Tomar
- Department of Microbiology and The Center for RNA Biology, The Ohio State University , Columbus, Ohio 43210, United States
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219
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Peske F, Kuhlenkoetter S, Rodnina MV, Wintermeyer W. Timing of GTP binding and hydrolysis by translation termination factor RF3. Nucleic Acids Res 2013; 42:1812-20. [PMID: 24214994 PMCID: PMC3919579 DOI: 10.1093/nar/gkt1095] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Protein synthesis in bacteria is terminated by release factors 1 or 2 (RF1/2), which, on recognition of a stop codon in the decoding site on the ribosome, promote the hydrolytic release of the polypeptide from the transfer RNA (tRNA). Subsequently, the dissociation of RF1/2 is accelerated by RF3, a guanosine triphosphatase (GTPase) that hydrolyzes GTP during the process. Here we show that—in contrast to a previous report—RF3 binds GTP and guanosine diphosphate (GDP) with comparable affinities. Furthermore, we find that RF3–GTP binds to the ribosome and hydrolyzes GTP independent of whether the P site contains peptidyl-tRNA (pre-termination state) or deacylated tRNA (post-termination state). RF3–GDP in either pre- or post-termination complexes readily exchanges GDP for GTP, and the exchange is accelerated when RF2 is present on the ribosome. Peptide release results in the stabilization of the RF3–GTP–ribosome complex, presumably due to the formation of the hybrid/rotated state of the ribosome, thereby promoting the dissociation of RF1/2. GTP hydrolysis by RF3 is virtually independent of the functional state of the ribosome and the presence of RF2, suggesting that RF3 acts as an unregulated ribosome-activated switch governed by its internal GTPase clock.
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Affiliation(s)
- Frank Peske
- Department of Physical Biochemistry, Max Planck Institute for Biophysical Chemistry, Am Fassberg 11, 37077 Göttingen, Germany
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220
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Liu X, Zheng M, Wang R, Wang R, An L, Rodermel SR, Yu F. Genetic interactions reveal that specific defects of chloroplast translation are associated with the suppression of var2-mediated leaf variegation. JOURNAL OF INTEGRATIVE PLANT BIOLOGY 2013; 55:979-93. [PMID: 23721655 DOI: 10.1111/jipb.12078] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/15/2013] [Accepted: 05/21/2013] [Indexed: 05/09/2023]
Abstract
Arabidopsis thaliana L. yellow variegated (var2) mutant is defective in a chloroplast FtsH family metalloprotease, AtFtsH2/VAR2, and displays an intriguing green and white leaf variegation. This unique var2-mediated leaf variegation offers a simple yet powerful tool for dissecting the genetic regulation of chloroplast development. Here, we report the isolation and characterization of a new var2 suppressor gene, SUPPRESSOR OF VARIEGATION8 (SVR8), which encodes a putative chloroplast ribosomal large subunit protein, L24. Mutations in SVR8 suppress var2 leaf variegation at ambient temperature and partially suppress the cold-induced chlorosis phenotype of var2. Loss of SVR8 causes unique chloroplast rRNA processing defects, particularly the 23S-4.5S dicistronic precursor. The recovery of the major abnormal processing site in svr8 23S-4.5S precursor indicate that it does not lie in the same position where SVR8/L24 binds on the ribosome. Surprisingly, we found that the loss of a chloroplast ribosomal small subunit protein, S21, results in aberrant chloroplast rRNA processing but not suppression of var2 variegation. These findings suggest that the disruption of specific aspects of chloroplast translation, rather than a general impairment in chloroplast translation, suppress var2 variegation and the existence of complex genetic interactions in chloroplast development.
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Affiliation(s)
- Xiayan Liu
- State Key Laboratory of Crop Stress Biology for Arid Areas and College of Life Sciences, Northwest A&F University, Yangling, 712100, China
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221
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Flores SC. Fast fitting to low resolution density maps: elucidating large-scale motions of the ribosome. Nucleic Acids Res 2013; 42:e9. [PMID: 24081579 PMCID: PMC3902909 DOI: 10.1093/nar/gkt906] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023] Open
Abstract
Determining the conformational rearrangements of large macromolecules is challenging experimentally and computationally. Case in point is the ribosome; it has been observed by high-resolution crystallography in several states, but many others are known only from low-resolution methods including cryo-electron microscopy. Combining these data into dynamical trajectories that may aid understanding of its largest-scale conformational changes has so far remained out of reach of computational methods. Most existing methods either model all atoms explicitly, resulting in often prohibitive cost, or use approximations that lose interesting structural and dynamical detail. In this work, I introduce Internal Coordinate Flexible Fitting, which uses full atomic forces and flexibility in limited regions of a model, capturing extensive conformational rearrangements at low cost. I use it to turn multiple low-resolution density maps, crystallographic structures and biochemical information into unified all-atoms trajectories of ribosomal translocation. Internal Coordinate Flexible Fitting is three orders of magnitude faster than the most comparable existing method.
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Affiliation(s)
- Samuel Coulbourn Flores
- Computational and Systems Biology Program, Department of Cell and Molecular Biology, Uppsala University, BMC Box 596, 75321 Uppsala, Sweden
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Förster F, Unverdorben P, Śledź P, Baumeister W. Unveiling the Long-Held Secrets of the 26S Proteasome. Structure 2013; 21:1551-62. [DOI: 10.1016/j.str.2013.08.010] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2013] [Revised: 08/15/2013] [Accepted: 08/16/2013] [Indexed: 01/23/2023]
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223
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Abstract
Nearly two decades after Westhof and Michel first proposed that RNA tetraloops may interact with distal helices, tetraloop–receptor interactions have been recognized as ubiquitous elements of RNA tertiary structure. The unique architecture of GNRA tetraloops (N=any nucleotide, R=purine) enables interaction with a variety of receptors, e.g., helical minor grooves and asymmetric internal loops. The most common example of the latter is the GAAA tetraloop–11 nt tetraloop receptor motif. Biophysical characterization of this motif provided evidence for the modularity of RNA structure, with applications spanning improved crystallization methods to RNA tectonics. In this review, we identify and compare types of GNRA tetraloop–receptor interactions. Then we explore the abundance of structural, kinetic, and thermodynamic information on the frequently occurring and most widely studied GAAA tetraloop–11 nt receptor motif. Studies of this interaction have revealed powerful paradigms for structural assembly of RNA, as well as providing new insights into the roles of cations, transition states and protein chaperones in RNA folding pathways. However, further research will clearly be necessary to characterize other tetraloop–receptor and long-range tertiary binding interactions in detail – an important milestone in the quantitative prediction of free energy landscapes for RNA folding.
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224
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Singh SB, Young K, Miesel L. Screening strategies for discovery of antibacterial natural products. Expert Rev Anti Infect Ther 2013; 9:589-613. [PMID: 21819327 DOI: 10.1586/eri.11.81] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Microbial-derived natural products have been a traditional source of antibiotics and antibiotic leads and continue to be effective sources of antibiotics today. The most important of these discoveries were made about 50 years ago. Chemical modifications of natural products discovered during those years continue to produce new clinical agents but their value is now, unfortunately, fading away owing to the exhaustion of opportunities of chemical modifications. The discovery of new natural antibiotics is directly linked to new screening technologies, particularly technologies that can help to eliminate the rediscovery of known antibiotics. In this article, we have reviewed the screening technologies from recent literature as well as originating from authors laboratories that were used for the screening of natural products. The article covers the entire spectrum of screening strategies, including classical empiric whole-cell assays to more sophisticated antisense based hypersensitive Staphylococcus aureus Fitness Test assays designed to screen all targets simultaneously. These technologies have led to the discovery of a series of natural product antibiotics, which have been summarized, including the discovery of platensimycin, platencin, nocathiacins, philipimycin, cyclothialidine and muryamycins. It is quite clear that natural products provide a tremendous opportunity to discover new antibiotics when combined with new hyper-sensitive whole-cell technologies.
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Affiliation(s)
- Sheo B Singh
- Merck Research Laboratories, Rahway, NJ 07065, USA.
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225
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Jiang J, Sakakibara Y, Chow CS. Helix 69: A Multitasking RNA Motif as a Novel Drug Target. Isr J Chem 2013. [DOI: 10.1002/ijch.201300012] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
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226
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Wang L, Wasserman MR, Feldman MB, Altman RB, Blanchard SC. Mechanistic insights into antibiotic action on the ribosome through single-molecule fluorescence imaging. Ann N Y Acad Sci 2013; 1241:E1-16. [PMID: 23419024 DOI: 10.1111/j.1749-6632.2012.06839.x] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Single-molecule fluorescence imaging has provided unprecedented access to the dynamics of ribosome function, revealing transient intermediate states that are critical to ribosome activity. Imaging platforms have now been developed that are capable of probing many hundreds of molecules simultaneously at temporal and spatial resolutions approaching the sub-millisecond time and the sub-nanometer scales. These advances enable both steady- and pre-steady state measurements of individual steps in the translation process as well as processive reactions. The data generated using these methods have yielded new, quantitative structural and kinetic insights into ribosomal activity. They have also shed light on the mechanisms of antibiotic targeting the translation apparatus, revealing features of the structure-function relationship that would be difficult to obtain by other means. This review provides an overview of the types of information that can be obtained using such imaging platforms and a blueprint for using the technique to assess how small-molecule antibiotics alter macromolecular functions.
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Affiliation(s)
- Leyi Wang
- Department of Physiology and Biophysics, Weill Cornell Medical College, New York, NY 10065, USA
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227
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Han B, Zhang L, Feng M, Fang Y, Li J. An Integrated Proteomics Reveals Pathological Mechanism of Honeybee (Apis cerena) Sacbrood Disease. J Proteome Res 2013; 12:1881-97. [DOI: 10.1021/pr301226d] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Bin Han
- Institute of Apicultural Research/Key Laboratory of
Pollinating Insect Biology, Ministry of Agriculture, Chinese Academy of Agricultural Science, Beijing, China
| | - Lan Zhang
- Institute of Apicultural Research/Key Laboratory of
Pollinating Insect Biology, Ministry of Agriculture, Chinese Academy of Agricultural Science, Beijing, China
| | - Mao Feng
- Institute of Apicultural Research/Key Laboratory of
Pollinating Insect Biology, Ministry of Agriculture, Chinese Academy of Agricultural Science, Beijing, China
| | - Yu Fang
- Institute of Apicultural Research/Key Laboratory of
Pollinating Insect Biology, Ministry of Agriculture, Chinese Academy of Agricultural Science, Beijing, China
| | - Jianke Li
- Institute of Apicultural Research/Key Laboratory of
Pollinating Insect Biology, Ministry of Agriculture, Chinese Academy of Agricultural Science, Beijing, China
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228
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Iost I, Bizebard T, Dreyfus M. Functions of DEAD-box proteins in bacteria: current knowledge and pending questions. BIOCHIMICA ET BIOPHYSICA ACTA-GENE REGULATORY MECHANISMS 2013; 1829:866-77. [PMID: 23415794 DOI: 10.1016/j.bbagrm.2013.01.012] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/28/2012] [Revised: 01/30/2013] [Accepted: 01/31/2013] [Indexed: 11/18/2022]
Abstract
DEAD-box proteins are RNA-dependent ATPases that are widespread in all three kingdoms of life. They are thought to rearrange the structures of RNA or ribonucleoprotein complexes but their exact mechanism of action is rarely known. Whereas in yeast most DEAD-box proteins are essential, no example of an essential bacterial DEAD-box protein has been reported so far; at most, their absence results in cold-sensitive growth. Moreover, whereas yeast DEAD-box proteins are implicated in virtually all reactions involving RNA, in E. coli (the bacterium where DEAD-box proteins have been mostly studied) their role is limited to ribosome biogenesis, mRNA degradation, and possibly translation initiation. Plausible reasons for these differences are discussed here. In spite of their dispensability, E. coli DEAD-box proteins are valuable models for the mechanism of action of DEAD-box proteins in general because the reactions in which they participate can be reproduced in vitro. Here we review our present understanding of this mechanism of action. Using selected examples for which information is available: (i) we describe how, by interacting directly with a particular RNA motif or by binding to proteins that themselves recognize such a motif, DEAD-box proteins are brought to their specific RNA substrate(s); (ii) we discuss the nature of the structural transitions that DEAD-box proteins induce on their substrates; and (iii) we analyze the reasons why these proteins are mostly important at low temperatures. This article is part of a Special Issue entitled: The Biology of RNA helicases-Modulation for life.
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Affiliation(s)
- Isabelle Iost
- Univ. Bordeaux, ARNA Laboratory, F-33000 Bordeaux, France.
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229
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SHARMA AJEETK, CHOWDHURY DEBASHISH. TEMPLATE-DIRECTED BIOPOLYMERIZATION: TAPE-COPYING TURING MACHINES. ACTA ACUST UNITED AC 2013. [DOI: 10.1142/s1793048012300083] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
DNA, RNA and proteins are among the most important macromolecules in a living cell. These molecules are polymerized by molecular machines. These natural nano-machines polymerize such macromolecules, adding one monomer at a time, using another linear polymer as the corresponding template. The machine utilizes input chemical energy to move along the template which also serves as a track for the movements of the machine. In the Alan Turing year 2012, it is worth pointing out that these machines are "tape-copying Turing machines". We review the operational mechanisms of the polymerizer machines and their collective behavior from the perspective of statistical physics, emphasizing their common features in spite of the crucial differences in their biological functions. We also draw the attention of the physics community to another class of modular machines that carry out a different type of template-directed polymerization. We hope this review will inspire new kinetic models for these modular machines.
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Affiliation(s)
- AJEET K. SHARMA
- Department of Physics, Indian Institute of Technology, Kanpur 208016, India
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230
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Graifer D, Karpova G. Photoactivatable RNA derivatives as tools for studying the structural and functional organization of complex cellular ribonucleoprotein machineries. RSC Adv 2013. [DOI: 10.1039/c2ra22095d] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
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231
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Seo SW, Yang JS, Kim I, Yang J, Min BE, Kim S, Jung GY. Predictive design of mRNA translation initiation region to control prokaryotic translation efficiency. Metab Eng 2013; 15:67-74. [DOI: 10.1016/j.ymben.2012.10.006] [Citation(s) in RCA: 166] [Impact Index Per Article: 15.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2012] [Revised: 05/23/2012] [Accepted: 10/12/2012] [Indexed: 12/22/2022]
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232
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Abstract
Legionella is a gram-negative bacterium and the causative pathogen of legionellosis-a severe pneumonia in humans. A large number of Legionella effectors interfere with numerous host cell functions, including intracellular vacuole trafficking and maturation, phospholipid metabolism, protein ubiquitination, pro-/anti-apoptotic balances or inflammatory responses. Moreover, eukaryotic protein synthesis is affected by L. pneumophila glucosyltransferases Lgt1, Lgt2, and Lgt3. Structurally, these enzymes are similar to large clostridial cytotoxins, use UDP-glucose as a co-substrate and modify a conserved serine residue (Ser-53) in elongation factor 1A (eEF1A). The ternary complex consisting of eEF1A, GTP, and aminoacylated-tRNA seems to be the substrate for Lgts. Studies with Saccharomyces cerevisiae corroborated that eEF1A is the major target responsible for Lgt-induced cytotoxic activity. In addition to Lgt proteins, Legionella produces other effector glycosyltransferase, including the modularly composed protein SetA, which displays tropism for early endosomal compartments, subverts host cell vesicle trafficking and demonstrates toxic activities toward yeast and mammalian cells. Here, our current knowledge about both groups of L. pneumophila glycosylating effectors is reviewed.
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233
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Li CD, Liu CL, Xia YY, Ge M, Chen DJ. SiRNA-mediated RPL31 gene silencing inhibits the growth of xenograft tumors derived from human pancreatic cancer BxPC-3 cells in nude mice. Shijie Huaren Xiaohua Zazhi 2012; 20:2782-2788. [DOI: 10.11569/wcjd.v20.i29.2782] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
AIM: To investigate the effect of siRNA-mediated RPL31 gene silencing on the growth of xenograft tumors derived from human pancreatic cancer cell line BxPC-3 in nude mice, and to explore the potential role of the RPL31 gene in pancreatic cancer.
METHODS: The siRNA sequence targeting to human RPL31 gene was designed. Human pancreatic cancer BxPC-3 cells were subcutaneously inoculated into Balb/c nude mice to develop a transplantation tumor model of human pancreatic cancer. According to the tumor volume, nude mice were randomly divided into three groups: vehicle control group, negative control group and RPL31-siRNA injection group. Mice of the RPL31-siRNA injection group were intratumorally injected with RPL31-siRNA using RNAi-Mate. Tumor volumes were calculated daily. On the 16th day after the first intratumoral injection, all the mice were sacrificed and the tumors were taken out to undergo real-time quantitative PCR (qRT-PCR) and Western blot analyses to detect RPL31 expression. The expression of Ki-67 and CD31 proteins in xenograft tissue was detected by immunohistochemistry. Cell apoptosis in xenograft tumors was detected by TUNEL assay.
RESULTS: Compared with the vehicle control group and negative control group, mice in the RPL31-siRNA injection group exhibited slower tumor growth, significantly smaller tumor volume (P < 0.05), and lower RPL31 expression level (P < 0.05). Immunohistochemistry results showed that the proportions of Ki-67- and CD31-positive cells decreased in xenograft tissue injected with RPL31-siRNA (55.78% ± 4.63%, 51.37% ± 5.05% vs 11.08% ± 1.31%; 56.53% ± 6.03%, 44.84% ± 5.24% vs9.67% ± 1.39%). TUNEL results showed that apoptosis increased in xenograft tissue injected with RPL31-siRNA (2.92% ± 0.54%, 3.85% ± 0.87% vs 39.58% ± 4.02%).
CONCLUSION: Silencing of RPL31 expression could inhibit the growth of subcutaneous xenograft tumors derived from BxPC-3 cell line in nude mice, down-regulate the expression of Ki-67 and CD31, and induce cell apoptosis in the transplantation tumors. The RPL31 gene is a potential target for gene therapy of pancreatic cancer.
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234
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Impact of vitamin B12 on formation of the tetrachloroethene reductive dehalogenase in Desulfitobacterium hafniense strain Y51. Appl Environ Microbiol 2012; 78:8025-32. [PMID: 22961902 DOI: 10.1128/aem.02173-12] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Corrinoids are essential cofactors of reductive dehalogenases in anaerobic bacteria. Microorganisms mediating reductive dechlorination as part of their energy metabolism are either capable of de novo corrinoid biosynthesis (e.g., Desulfitobacterium spp.) or dependent on exogenous vitamin B(12) (e.g., Dehalococcoides spp.). In this study, the impact of exogenous vitamin B(12) (cyanocobalamin) and of tetrachloroethene (PCE) on the synthesis and the subcellular localization of the reductive PCE dehalogenase was investigated in the gram-positive Desulfitobacterium hafniense strain Y51, a bacterium able to synthesize corrinoids de novo. PCE-depleted cells grown for several subcultivation steps on fumarate as an alternative electron acceptor lost the tetrachloroethene-reductive dehalogenase (PceA) activity by the transposition of the pce gene cluster. In the absence of vitamin B(12), a gradual decrease of the PceA activity and protein amount was observed; after 5 subcultivation steps with 10% inoculum, more than 90% of the enzyme activity and of the PceA protein was lost. In the presence of vitamin B(12), a significant delay in the decrease of the PceA activity with an ∼90% loss after 20 subcultivation steps was observed. This corresponded to the decrease in the pceA gene level, indicating that exogenous vitamin B(12) hampered the transposition of the pce gene cluster. In the absence or presence of exogenous vitamin B(12), the intracellular corrinoid level decreased in fumarate-grown cells and the PceA precursor formed catalytically inactive, corrinoid-free multiprotein aggregates. The data indicate that exogenous vitamin B(12) is not incorporated into the PceA precursor, even though it affects the transposition of the pce gene cluster.
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235
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Jo JJ, Kim JH, Shin JS. Probing translation initiation through ligand binding to the 5' mRNA coding region. Chembiochem 2012; 13:2048-51. [PMID: 22927129 DOI: 10.1002/cbic.201200432] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2012] [Indexed: 11/08/2022]
Abstract
Secondary structure matters: We have constructed artificial intragenic riboswitches to probe ribosome accessibility to the 5' mRNA coding region at three-base resolution in Escherichia coli. We show that only mRNA folding stability in the +1 to +15 nt region affects the translation process.
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Affiliation(s)
- Joon-Jung Jo
- Department of Biotechnology, Yonsei University, Shinchon-Dong 134, Seoul 120-749, South Korea
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236
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Behnen P, Davis E, Delaney E, Frohm B, Bauer M, Cedervall T, O'Connell D, Åkerfeldt KS, Linse S. Calcium-dependent interaction of calmodulin with human 80S ribosomes and polyribosomes. Biochemistry 2012; 51:6718-27. [PMID: 22856685 DOI: 10.1021/bi3005939] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Ribosomes are the protein factories of every living cell. The process of protein translation is highly complex and tightly regulated by a large number of diverse RNAs and proteins. Earlier studies indicate that Ca(2+) plays a role in protein translation. Calmodulin (CaM), a ubiquitous Ca(2+)-binding protein, regulates a large number of proteins participating in many signaling pathways. Several 40S and 60S ribosomal proteins have been identified to interact with CaM, and here, we report that CaM binds with high affinity to 80S ribosomes and polyribosomes in a Ca(2+)-dependent manner. No binding is observed in buffer with 6 mM Mg(2+) and 1 mM EGTA that chelates Ca(2+), suggesting high specificity of the CaM-ribosome interaction dependent on the Ca(2+) induced conformational change of CaM. The interactions between CaM and ribosomes are inhibited by synthetic peptides comprising putative CaM-binding sites in ribosomal proteins S2 and L14. Using a cell-free in vitro translation system, we further found that these synthetic peptides are potent inhibitors of protein synthesis. Our results identify an involvement of CaM in the translational activity of ribosomes.
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Affiliation(s)
- Petra Behnen
- Biophysical Chemistry and Biochemistry, Lund University, Chemical Centre, P.O. Box 124, SE-221 00 Lund, Sweden.
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237
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Diphthamide modification on eukaryotic elongation factor 2 is needed to assure fidelity of mRNA translation and mouse development. Proc Natl Acad Sci U S A 2012; 109:13817-22. [PMID: 22869748 DOI: 10.1073/pnas.1206933109] [Citation(s) in RCA: 74] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
To study the role of the diphthamide modification on eukaryotic elongation factor 2 (eEF2), we generated an eEF2 Gly(717)Arg mutant mouse, in which the first step of diphthamide biosynthesis is prevented. Interestingly, the Gly(717)-to-Arg mutation partially compensates the eEF2 functional loss resulting from diphthamide deficiency, possibly because the added +1 charge compensates for the loss of the +1 charge on diphthamide. Therefore, in contrast to mouse embryonic fibroblasts (MEFs) from OVCA1(-/-) mice, eEF2(G717R/G717R) MEFs retain full activity in polypeptide elongation and have normal growth rates. Furthermore, eEF2(G717R/G717R) mice showed milder phenotypes than OVCA1(-/-) mice (which are 100% embryonic lethal) and a small fraction survived to adulthood without obvious abnormalities. Moreover, eEF2(G717R/G717R)/OVCA1(-/-) double mutant mice displayed the milder phenotypes of the eEF2(G717R/G717R) mice, suggesting that the embryonic lethality of OVCA1(-/-) mice is due to diphthamide deficiency. We confirmed that the diphthamide modification is essential for eEF2 to prevent -1 frameshifting during translation and show that the Gly(717)-to-Arg mutation cannot rescue this defect.
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238
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Nagano T, Kojima K, Hisabori T, Hayashi H, Morita EH, Kanamori T, Miyagi T, Ueda T, Nishiyama Y. Elongation factor G is a critical target during oxidative damage to the translation system of Escherichia coli. J Biol Chem 2012; 287:28697-704. [PMID: 22773838 DOI: 10.1074/jbc.m112.378067] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
Elongation factor G (EF-G), a key protein in translational elongation, is known to be particularly susceptible to oxidation in Escherichia coli. However, neither the mechanism of the oxidation of EF-G nor the influence of its oxidation on translation is fully understood. In the present study, we investigated the effects of oxidants on the chemical properties and function of EF-G using a translation system in vitro derived from E. coli. Treatment of EF-G with 0.5 mM H(2)O(2) resulted in the complete loss of translational activity. The inactivation of EF-G by H(2)O(2) was attributable to the oxidation of two specific cysteine residues, namely, Cys(114) and Cys(266), and subsequent formation of an intramolecular disulfide bond. Replacement of Cys(114) by serine rendered EF-G insensitive to oxidation and inactivation by H(2)O(2). Furthermore, generation of the translation system in vitro with the mutated EF-G protected the entire translation system from oxidation, suggesting that EF-G might be a primary target of oxidation within the translation system. Oxidized EF-G was reactivated via reduction of the disulfide bond by thioredoxin, a ubiquitous protein that mediates dithiol-disulfide exchange. Our observations indicate that the translational machinery in E. coli is regulated, in part, by the redox state of EF-G, which might depend on the balance between the supply of reducing power and the degree of oxidative stress.
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Affiliation(s)
- Takanori Nagano
- Department of Biochemistry and Molecular Biology, Graduate School of Science and Engineering, Saitama University, 255 Shimo-Okubo, Sakura-ku, Saitama 338-8570, Japan
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239
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Belyi Y, Tartakovskaya D, Tais A, Fitzke E, Tzivelekidis T, Jank T, Rospert S, Aktories K. Elongation factor 1A is the target of growth inhibition in yeast caused by Legionella pneumophila glucosyltransferase Lgt1. J Biol Chem 2012; 287:26029-37. [PMID: 22685293 DOI: 10.1074/jbc.m112.372672] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Legionella is a pathogenic Gram-negative bacterium that can multiply inside of eukaryotic cells. It translocates numerous bacterial effector proteins into target cells to transform host phagocytes into a niche for replication. One effector of Legionella pneumophila is the glucosyltransferase Lgt1, which modifies serine 53 in mammalian elongation factor 1A (eEF1A), resulting in inhibition of protein synthesis and cell death. Here, we demonstrate that similar to mammalian cells, Lgt1 was severely toxic when produced in yeast and effectively inhibited in vitro protein synthesis. Saccharomyces cerevisiae strains, which were deleted of endogenous eEF1A but harbored a mutant eEF1A not glucosylated by Lgt1, were resistant toward the bacterial effector. In contrast, deletion of Hbs1, which is also an in vitro substrate of the glucosyltransferase, did not influence the toxic effects of Lgt1. Serial mutagenesis in yeast showed that Phe(54), Tyr(56) and Trp(58), located immediately downstream of serine 53 of eEF1A, are essential for the function of the elongation factor. Replacement of serine 53 by glutamic acid, mimicking phosphorylation, produced a non-functional eEF1A, which failed to support growth of S. cerevisiae. Our data indicate that Lgt1-induced lethal effect in yeast depends solely on eEF1A. The region of eEF1A encompassing serine 53 plays a critical role in functioning of the elongation factor.
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Affiliation(s)
- Yury Belyi
- Gamaleya Research Institute, Moscow 123098, Russia
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240
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Yutin N, Puigbò P, Koonin EV, Wolf YI. Phylogenomics of prokaryotic ribosomal proteins. PLoS One 2012; 7:e36972. [PMID: 22615861 PMCID: PMC3353972 DOI: 10.1371/journal.pone.0036972] [Citation(s) in RCA: 189] [Impact Index Per Article: 15.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2011] [Accepted: 04/16/2012] [Indexed: 11/29/2022] Open
Abstract
Archaeal and bacterial ribosomes contain more than 50 proteins, including 34 that are universally conserved in the three domains of cellular life (bacteria, archaea, and eukaryotes). Despite the high sequence conservation, annotation of ribosomal (r-) protein genes is often difficult because of their short lengths and biased sequence composition. We developed an automated computational pipeline for identification of r-protein genes and applied it to 995 completely sequenced bacterial and 87 archaeal genomes available in the RefSeq database. The pipeline employs curated seed alignments of r-proteins to run position-specific scoring matrix (PSSM)-based BLAST searches against six-frame genome translations, mitigating possible gene annotation errors. As a result of this analysis, we performed a census of prokaryotic r-protein complements, enumerated missing and paralogous r-proteins, and analyzed the distributions of ribosomal protein genes among chromosomal partitions. Phyletic patterns of bacterial and archaeal r-protein genes were mapped to phylogenetic trees reconstructed from concatenated alignments of r-proteins to reveal the history of likely multiple independent gains and losses. These alignments, available for download, can be used as search profiles to improve genome annotation of r-proteins and for further comparative genomics studies.
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Affiliation(s)
- Natalya Yutin
- National Center for Biotechnology Information, National Library of Medicine, National Institutes of Health, Bethesda, Maryland, United States of America
| | - Pere Puigbò
- National Center for Biotechnology Information, National Library of Medicine, National Institutes of Health, Bethesda, Maryland, United States of America
| | - Eugene V. Koonin
- National Center for Biotechnology Information, National Library of Medicine, National Institutes of Health, Bethesda, Maryland, United States of America
| | - Yuri I. Wolf
- National Center for Biotechnology Information, National Library of Medicine, National Institutes of Health, Bethesda, Maryland, United States of America
- * E-mail:
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241
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Sudhamalla B, Yadaiah M, Ramakrishna D, Bhuyan AK. Cysteine protease attribute of eukaryotic ribosomal protein S4. Biochim Biophys Acta Gen Subj 2012; 1820:1535-42. [PMID: 22579920 DOI: 10.1016/j.bbagen.2012.05.001] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2012] [Revised: 04/25/2012] [Accepted: 05/03/2012] [Indexed: 12/29/2022]
Abstract
BACKGROUND Ribosomal proteins often carry out extraribosomal functions. The protein S4 from the smaller subunit of Escherichia coli, for instance, regulates self synthesis and acts as a transcription factor. In humans, S4 might be involved in Turner syndrome. Recent studies also associate many ribosomal proteins with malignancy, and cell death and survival. The list of extraribosomal functions of ribosomal proteins thus continues to grow. METHODS Enzymatic action of recombinant wheat S4 on fluorogenic peptide substrates Ac-XEXD↓-AFC (N-acetyl-residue-Glu-residue-Asp-7-amino-4-trifluoromethylcoumarin) and Z-FR↓-AMC (N-CBZ-Phe-Arg-aminomethylcoumarin) as well as proteins has been examined under a variety of solution conditions. RESULTS Eukaryotic ribosomal protein S4 is an endoprotease exhibiting all characteristics of cysteine proteases. The K(m) value for the cleavage of Z-FR↓-AMC by a cysteine mutant (C41F) is about 70-fold higher relative to that for the wild-type protein under identical conditions, implying that S4 is indeed a cysteine protease. Interestingly, activity responses of the S4 protein and caspases toward environmental parameters, including pH, temperature, ionic strength, and Mg(2+) and Zn(2+) concentrations, are quite similar. Respective kinetic constants for their cleavage action on Ac-LEHD↓-AFC are also similar. However, S4 cannot be a caspase, because unlike the latter it also hydrolyzes the cathepsin substrate Z-FR↓-AMC. GENERAL SIGNIFICANCE The eukaryotic S4 is a generic cysteine protease capable of hydrolyzing a broad spectrum of synthetic substrates and proteins. The enzyme attribute of eukaryotic ribosomal protein S4 is a new phenomenon. Its possible involvement in cell growth and proliferations are presented in the light of known extraribosomal roles of ribosomal proteins.
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Affiliation(s)
- Babu Sudhamalla
- School of Chemistry, University of Hyderabad, Hyderabad 500 046, India
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242
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Klinge S, Voigts-Hoffmann F, Leibundgut M, Ban N. Atomic structures of the eukaryotic ribosome. Trends Biochem Sci 2012; 37:189-98. [DOI: 10.1016/j.tibs.2012.02.007] [Citation(s) in RCA: 130] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2011] [Revised: 02/10/2012] [Accepted: 02/16/2012] [Indexed: 12/20/2022]
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243
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Graifer D, Karpova G. Structural and functional topography of the human ribosome. Acta Biochim Biophys Sin (Shanghai) 2012; 44:281-99. [PMID: 22257731 DOI: 10.1093/abbs/gmr118] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
This review covers data on the structural organization of functional sites in the human ribosome, namely, the messenger RNA binding center, the binding site of the hepatitis C virus RNA internal ribosome entry site, and the peptidyl transferase center. The data summarized here have been obtained primarily by means of a site-directed cross-linking approach with application of the analogs of the respective ribosomal ligands bearing cross-linkers at the designed positions. These data are discussed taking into consideration available structural data on ribosomes from various kingdoms obtained with the use of cryo-electron microscopy, X-ray crystallography, and other approaches.
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Affiliation(s)
- Dmitri Graifer
- Laboratory of Ribosome Structure and Functions, Institute of Chemical Biology and Fundamental Medicine, Siberian Branch of the Russian Academy of Sciences, Novosibirsk, Russia
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244
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Shasmal M, Sengupta J. Structural diversity in bacterial ribosomes: mycobacterial 70S ribosome structure reveals novel features. PLoS One 2012; 7:e31742. [PMID: 22384065 PMCID: PMC3286452 DOI: 10.1371/journal.pone.0031742] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2011] [Accepted: 01/12/2012] [Indexed: 12/25/2022] Open
Abstract
Here we present analysis of a 3D cryo-EM map of the 70S ribosome from Mycobacterium smegmatis, a saprophytic cousin of the etiological agent of tuberculosis in humans, Mycobacterium tuberculosis. In comparison with the 3D structures of other prokaryotic ribosomes, the density map of the M. smegmatis 70S ribosome reveals unique structural features and their relative orientations in the ribosome. Dramatic changes in the periphery due to additional rRNA segments and extra domains of some of the peripheral ribosomal proteins like S3, S5, S16, L17, L25, are evident. One of the most notable features appears in the large subunit near L1 stalk as a long helical structure next to helix 54 of the 23S rRNA. The sharp upper end of this structure is located in the vicinity of the mRNA exit channel. Although the M. smegmatis 70S ribosome possesses conserved core structure of bacterial ribosome, the new structural features, unveiled in this study, demonstrates diversity in the 3D architecture of bacterial ribosomes. We postulate that the prominent helical structure related to the 23S rRNA actively participates in the mechanisms of translation in mycobacteria.
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Affiliation(s)
| | - Jayati Sengupta
- Structural Biology and Bio-Informatics Division, Indian Institute of Chemical Biology (Council of Scientific and Industrial Research), Jadavpur, Kolkata, West Bengal, India
- * E-mail:
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245
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Wang K, Schmied WH, Chin JW. Reprogramming the genetic code: from triplet to quadruplet codes. Angew Chem Int Ed Engl 2012; 51:2288-97. [PMID: 22262408 DOI: 10.1002/anie.201105016] [Citation(s) in RCA: 74] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2011] [Indexed: 11/10/2022]
Abstract
The genetic code of cells is near-universally triplet, and since many ribosomal mutations are lethal, changing the cellular ribosome to read nontriplet codes is challenging. Herein we review work on the incorporation of unnatural amino acids into proteins in response to quadruplet codons, and the creation of an orthogonal translation system in the cell that uses an evolved orthogonal ribosome to efficiently direct the incorporation of unnatural amino acids in response to quadruplet codons. Using this system multiple distinct unnatural amino acids have been incorporated and used to genetically program emergent properties into recombinant proteins. Extension of approaches to incorporate multiple unnatural amino acids may allow the combinatorial biosynthesis of materials and therapeutics, and drive investigations into whether life with additional genetically encoded polymers can evolve to perform functions that natural biological systems cannot.
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Affiliation(s)
- Kaihang Wang
- Medical Research Council Laboratory of Molecular Biology, Hills Rd, Cambridge, CB2 0QH UK
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246
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Wang K, Schmied WH, Chin JW. Die Umprogrammierung des genetischen Codes: vom Triplett- zum Quadruplettcode. Angew Chem Int Ed Engl 2012. [DOI: 10.1002/ange.201105016] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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247
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Affiliation(s)
- Ofer I. Wilner
- Institute of Chemistry, Center for Nanoscience and Nanotechnology, The Hebrew University of Jerusalem, Jerusalem 91904, Israel
| | - Itamar Willner
- Institute of Chemistry, Center for Nanoscience and Nanotechnology, The Hebrew University of Jerusalem, Jerusalem 91904, Israel
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248
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Structure and dynamics of the mammalian ribosomal pretranslocation complex. Mol Cell 2011; 44:214-24. [PMID: 22017870 DOI: 10.1016/j.molcel.2011.07.040] [Citation(s) in RCA: 85] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2011] [Revised: 06/06/2011] [Accepted: 07/24/2011] [Indexed: 11/20/2022]
Abstract
Although the structural core of the ribosome is conserved in all kingdoms of life, eukaryotic ribosomes are significantly larger and more complex than their bacterial counterparts. The extent to which these differences influence the molecular mechanism of translation remains elusive. Multiparticle cryo-electron microscopy and single-molecule FRET investigations of the mammalian pretranslocation complex reveal spontaneous, large-scale conformational changes, including an intersubunit rotation of the ribosomal subunits. Through structurally related processes, tRNA substrates oscillate between classical and at least two distinct hybrid configurations facilitated by localized changes in their L-shaped fold. Hybrid states are favored within the mammalian complex. However, classical tRNA positions can be restored by tRNA binding to the E site or by the eukaryotic-specific antibiotic and translocation inhibitor cycloheximide. These findings reveal critical distinctions in the structural and energetic features of bacterial and mammalian ribosomes, providing a mechanistic basis for divergent translation regulation strategies and species-specific antibiotic action.
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249
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Abstract
Many RNAs do not directly code proteins but are nonetheless indispensable to cellular function. These strands fold into intricate three-dimensional shapes that are essential structures in protein synthesis, splicing, and many other processes of gene regulation and expression. A variety of biophysical and biochemical methods are now showing, in real time, how ribosomal subunits and other ribonucleoprotein complexes assemble from their molecular components. Footprinting methods are particularly useful for studying the folding of long RNAs: they provide quantitative information about the conformational state of each residue and require little material. Data from footprinting complement the global information available from small-angle X-ray scattering or cryo-electron microscopy, as well as the dynamic information derived from single-molecule Förster resonance energy transfer (FRET) and NMR methods. In this Account, I discuss how we have used hydroxyl radical footprinting and other experimental methods to study pathways of RNA folding and 30S ribosome assembly. Hydroxyl radical footprinting probes the solvent accessibility of the RNA backbone at each residue in as little as 10 ms, providing detailed views of RNA folding pathways in real time. In conjunction with other methods such as solution scattering and single-molecule FRET, time-resolved footprinting of ribozymes showed that stable domains of RNA tertiary structure fold in less than 1 s. However, the free energy landscapes for RNA folding are rugged, and individual molecules kinetically partition into folding pathways that lead through metastable intermediates, stalling the folding or assembly process. Time-resolved footprinting was used to follow the formation of tertiary structure and protein interactions in the 16S ribosomal RNA (rRNA) during the assembly of 30S ribosomes. As previously observed in much simpler ribozymes, assembly occurs in stages, with individual molecules taking different routes to the final complex. Interactions occur concurrently in all domains of the 16S rRNA, and multistage protection of binding sites of individual proteins suggests that initial encounter complexes between the rRNA and ribosomal proteins are remodeled during assembly. Equilibrium footprinting experiments showed that one primary binding protein was sufficient to stabilize the tertiary structure of the entire 16S 5'-domain. The rich detail available from the footprinting data showed that the secondary assembly protein S16 suppresses non-native structures in the 16S 5'-domain. In doing so, S16 enables a conformational switch distant from its own binding site, which may play a role in establishing interactions with other domains of the 30S subunit. Together, the footprinting results show how protein-induced changes in RNA structure are communicated over long distances, ensuring cooperative assembly of even very large RNA-protein complexes such as the ribosome.
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Affiliation(s)
- Sarah A. Woodson
- T. C. Jenkins Department of Biophysics, Johns Hopkins University, 3400 North Charles Street, Baltimore, Maryland 21218, United States
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250
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Sharifulin D, Khairulina Y, Ivanov A, Meschaninova M, Ven'yaminova A, Graifer D, Karpova G. A central fragment of ribosomal protein S26 containing the eukaryote-specific motif YxxPKxYxK is a key component of the ribosomal binding site of mRNA region 5' of the E site codon. Nucleic Acids Res 2011; 40:3056-65. [PMID: 22167470 PMCID: PMC3326325 DOI: 10.1093/nar/gkr1212] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
The eukaryotic ribosomal protein S26e (rpS26e) lacking eubacterial counterparts is a key component of the ribosomal binding site of mRNA region 5′ of the codon positioned at the exit site. Here, we determined the rpS26e oligopeptide neighboring mRNA on the human 80S ribosome using mRNA analogues bearing perfluorophenyl azide-derivatized nucleotides at designed locations. The protein was cross-linked to mRNA analogues in specific ribosomal complexes, in which the derivatized nucleotide was located at positions −3 to −9. Digestion of cross-linked rpS26e with various specific proteolytic agents followed by identification of the resulting modified oligopeptides made it possible to map the cross-links to fragment 60–71. This fragment contains the motif YxxPKxYxK conserved in eukaryotic but not in archaeal rpS26e. Analysis of X-ray structure of the Tetrahymena thermophila 40S subunit showed that this motif is not implicated in the intraribosomal interactions, implying its involvement in translation process in a eukaryote-specific manner. Comparison of the results obtained with data on positioning of ribosomal ligands on the 40S subunit lead us to suggest that this motif is involved in interaction with both the 5′-untranslated region of mRNA and the initiation factor eIF3 specific for eukaryotes, providing new insights into molecular mechanisms of translation in eukaryotes.
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Affiliation(s)
- Dmitri Sharifulin
- Institute of Chemical Biology and Fundamental Medicine, Siberian Branch of Russian Academy of Sciences, Novosibirsk 630090, Russia
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