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Kuzminov A. Bacterial nucleoid is a riddle wrapped in a mystery inside an enigma. J Bacteriol 2024; 206:e0021123. [PMID: 38358278 PMCID: PMC10994824 DOI: 10.1128/jb.00211-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/16/2024] Open
Abstract
Bacterial chromosome, the nucleoid, is traditionally modeled as a rosette of DNA mega-loops, organized around proteinaceous central scaffold by nucleoid-associated proteins (NAPs), and mixed with the cytoplasm by transcription and translation. Electron microscopy of fixed cells confirms dispersal of the cloud-like nucleoid within the ribosome-filled cytoplasm. Here, I discuss evidence that the nucleoid in live cells forms DNA phase separate from riboprotein phase, the "riboid." I argue that the nucleoid-riboid interphase, where DNA interacts with NAPs, transcribing RNA polymerases, nascent transcripts, and ssRNA chaperones, forms the transcription zone. An active part of phase separation, transcription zone enforces segregation of the centrally positioned information phase (the nucleoid) from the surrounding action phase (the riboid), where translation happens, protein accumulates, and metabolism occurs. I speculate that HU NAP mostly tiles up the nucleoid periphery-facilitating DNA mobility but also supporting transcription in the interphase. Besides extruding plectonemically supercoiled DNA mega-loops, condensins could compact them into solenoids of uniform rings, while HU could support rigidity and rotation of these DNA rings. The two-phase cytoplasm arrangement allows the bacterial cell to organize the central dogma activities, where (from the cell center to its periphery) DNA replicates and segregates, DNA is transcribed, nascent mRNA is handed over to ribosomes, mRNA is translated into proteins, and finally, the used mRNA is recycled into nucleotides at the inner membrane. The resulting information-action conveyor, with one activity naturally leading to the next one, explains the efficiency of prokaryotic cell design-even though its main intracellular transportation mode is free diffusion.
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Affiliation(s)
- Andrei Kuzminov
- Department of Microbiology, University of Illinois Urbana-Champaign, Urbana, Illinois, USA
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2
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Choi H, Covert MW. Whole-cell modeling of E. coli confirms that in vitro tRNA aminoacylation measurements are insufficient to support cell growth and predicts a positive feedback mechanism regulating arginine biosynthesis. Nucleic Acids Res 2023; 51:5911-5930. [PMID: 37224536 PMCID: PMC10325894 DOI: 10.1093/nar/gkad435] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2023] [Revised: 05/04/2023] [Accepted: 05/09/2023] [Indexed: 05/26/2023] Open
Abstract
In Escherichia coli, inconsistencies between in vitro tRNA aminoacylation measurements and in vivo protein synthesis demands were postulated almost 40 years ago, but have proven difficult to confirm. Whole-cell modeling can test whether a cell behaves in a physiologically correct manner when parameterized with in vitro measurements by providing a holistic representation of cellular processes in vivo. Here, a mechanistic model of tRNA aminoacylation, codon-based polypeptide elongation, and N-terminal methionine cleavage was incorporated into a developing whole-cell model of E. coli. Subsequent analysis confirmed the insufficiency of aminoacyl-tRNA synthetase kinetic measurements for cellular proteome maintenance, and estimated aminoacyl-tRNA synthetase kcats that were on average 7.6-fold higher. Simulating cell growth with perturbed kcats demonstrated the global impact of these in vitro measurements on cellular phenotypes. For example, an insufficient kcat for HisRS caused protein synthesis to be less robust to the natural variability in aminoacyl-tRNA synthetase expression in single cells. More surprisingly, insufficient ArgRS activity led to catastrophic impacts on arginine biosynthesis due to underexpressed N-acetylglutamate synthase, where translation depends on repeated CGG codons. Overall, the expanded E. coli model deepens understanding of how translation operates in an in vivo context.
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Affiliation(s)
- Heejo Choi
- Department of Bioengineering, Stanford University, 443 Via Ortega, Stanford, CA 94305, USA
| | - Markus W Covert
- Department of Bioengineering, Stanford University, 443 Via Ortega, Stanford, CA 94305, USA
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Guo H, Wang N, Ding T, Zheng B, Guo L, Huang C, Zhang W, Sun L, Ma X, Huo YX. A tRNAModification-based strategy for Identifying amiNo acid Overproducers (AMINO). Metab Eng 2023; 78:11-25. [PMID: 37149082 DOI: 10.1016/j.ymben.2023.04.012] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2023] [Revised: 04/05/2023] [Accepted: 04/23/2023] [Indexed: 05/08/2023]
Abstract
Amino acids have a multi-billion-dollar market with rising demand, prompting the development of high-performance microbial factories. However, a general screening strategy applicable to all proteinogenic and non-proteinogenic amino acids is still lacking. Modification of the critical structure of tRNA could decrease the aminoacylation level of tRNA catalyzed by aminoacyl-tRNA synthetases. Involved in a two-substrate sequential reaction, amino acids with increased concentration could elevate the reduced aminoacylation rate caused by specific tRNA modification. Here, we developed a selection system for overproducers of specific amino acids using corresponding engineered tRNAs and marker genes. As a proof-of-concept, overproducers of five amino acids such as L-tryptophan were screened out by growth-based and/or fluorescence-activated cell sorting (FACS)-based screening from random mutation libraries of Escherichia coli and Corynebacterium glutamicum, respectively. This study provided a universal strategy that could be applied to screen overproducers of proteinogenic and non-proteinogenic amino acids in amber-stop-codon-recoded or non-recoded hosts.
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Affiliation(s)
- Hao Guo
- Key Laboratory of Molecular Medicine and Biotherapy, School of Life Science, Beijing Institute of Technology, No. 5 South Zhongguancun Street, Beijing, 100081, PR China; Beijing Institute of Technology (Tangshan) Translational Research Center, Tangshan Port Economic Development Zone, Tangshan, 063611, PR China
| | - Ning Wang
- Key Laboratory of Plant Resources, Institute of Botany, Chinese Academy of Sciences, Beijing, 100093, PR China
| | - Tingting Ding
- Key Laboratory of Molecular Medicine and Biotherapy, School of Life Science, Beijing Institute of Technology, No. 5 South Zhongguancun Street, Beijing, 100081, PR China
| | - Bo Zheng
- Key Laboratory of Molecular Medicine and Biotherapy, School of Life Science, Beijing Institute of Technology, No. 5 South Zhongguancun Street, Beijing, 100081, PR China
| | - Liwei Guo
- Key Laboratory of Molecular Medicine and Biotherapy, School of Life Science, Beijing Institute of Technology, No. 5 South Zhongguancun Street, Beijing, 100081, PR China
| | - Chaoyong Huang
- Key Laboratory of Molecular Medicine and Biotherapy, School of Life Science, Beijing Institute of Technology, No. 5 South Zhongguancun Street, Beijing, 100081, PR China
| | - Wuyuan Zhang
- Key Laboratory of Molecular Medicine and Biotherapy, School of Life Science, Beijing Institute of Technology, No. 5 South Zhongguancun Street, Beijing, 100081, PR China
| | - Lichao Sun
- Key Laboratory of Molecular Medicine and Biotherapy, School of Life Science, Beijing Institute of Technology, No. 5 South Zhongguancun Street, Beijing, 100081, PR China
| | - Xiaoyan Ma
- Key Laboratory of Molecular Medicine and Biotherapy, School of Life Science, Beijing Institute of Technology, No. 5 South Zhongguancun Street, Beijing, 100081, PR China; Beijing Institute of Technology (Tangshan) Translational Research Center, Tangshan Port Economic Development Zone, Tangshan, 063611, PR China.
| | - Yi-Xin Huo
- Key Laboratory of Molecular Medicine and Biotherapy, School of Life Science, Beijing Institute of Technology, No. 5 South Zhongguancun Street, Beijing, 100081, PR China; Beijing Institute of Technology (Tangshan) Translational Research Center, Tangshan Port Economic Development Zone, Tangshan, 063611, PR China.
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4
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Colloidal Physics Modeling Reveals How Per-Ribosome Productivity Increases with Growth Rate in Escherichia coli. mBio 2023; 14:e0286522. [PMID: 36537810 PMCID: PMC9973364 DOI: 10.1128/mbio.02865-22] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023] Open
Abstract
Faster-growing cells must synthesize proteins more quickly. Increased ribosome abundance only partly accounts for increases in total protein synthesis rates. The productivity of individual ribosomes must increase too, almost doubling by an unknown mechanism. Prior models point to diffusive transport as a limiting factor but raise a paradox: faster-growing cells are more crowded, yet crowding slows diffusion. We suspected that physical crowding, transport, and stoichiometry, considered together, might reveal a more nuanced explanation. To investigate, we built a first-principles physics-based model of Escherichia coli cytoplasm in which Brownian motion and diffusion arise directly from physical interactions between individual molecules of finite size, density, and physiological abundance. Using our microscopically detailed model, we predicted that physical transport of individual ternary complexes accounts for ~80% of translation elongation latency. We also found that volumetric crowding increases during faster growth even as cytoplasmic mass density remains relatively constant. Despite slowed diffusion, we predicted that improved proximity between ternary complexes and ribosomes wins out, illustrating a simple physics-based mechanism for how individual elongating ribosomes become more productive. We speculate that crowding imposes a physical limit on growth rate and undergirds cellular behavior more broadly. Unfitted colloidal-scale modeling offers systems biology a complementary "physics engine" for exploring how cellular-scale behaviors arise from physical transport and reactions among individual molecules. IMPORTANCE Ribosomes are the factories in cells that synthesize proteins. When cells grow faster, there are not enough ribosomes to keep up with the demand for faster protein synthesis without individual ribosomes becoming more productive. Yet, faster-growing cells are more crowded, seemingly making it harder for each ribosome to do its work. Our computational model of the physics of translation elongation reveals the underlying mechanism for how individual ribosomes become more productive: proximity and stoichiometry of translation molecules overcome crowding. Our model also suggests a universal physical limitation of cell growth rates.
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5
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Leiva LE, Elgamal S, Leidel SA, Orellana O, Ibba M, Katz A. Oxidative stress strongly restricts the effect of codon choice on the efficiency of protein synthesis in Escherichia coli. Front Microbiol 2022; 13:1042675. [DOI: 10.3389/fmicb.2022.1042675] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2022] [Accepted: 11/04/2022] [Indexed: 11/30/2022] Open
Abstract
IntroductionThe response of enterobacteria to oxidative stress is usually considered to be regulated by transcription factors such as OxyR and SoxR. Nevertheless, several reports have shown that under oxidative stress the levels, modification and aminoacylation of tRNAs may be altered suggesting a role of codon bias in regulation of gene expression under this condition.MethodsIn order to characterize the effects of oxidative stress on translation elongation we constructed a library of 61 plasmids, each coding for the green fluorescent protein (GFP) translationally fused to a different set of four identical codons.ResultsUsing these reporters, we observed that GFP production levels vary widely (~15 fold) when Escherichia coli K-12 is cultured in minimal media as a consequence of codon choice variations. When bacteria are cultured under oxidative stress caused by paraquat the levels of GFP produced by most clones is reduced and, in contrast to control conditions, the range of GFP levels is restricted to a ~2 fold range. Restricting elongation of particular sequences does not increase the range of GFP production under oxidative stress, but altering translation initiation rates leads to an increase in this range.DiscussionAltogether, our results suggest that under normal conditions the speed of translation elongation is in the range of the speed of initiation and, consequently, codon choice impacts the speed of protein synthesis. In contrast, under oxidative stress translation initiation becomes much slower than elongation, limiting the speed of translation such that codon choice has at most only subtle effects on the overall output of translation.
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Tsukamoto Y, Nakamura Y, Hirata M, Sakate R, Kimura T. i-tRAP (individual tRNA acylation PCR): A convenient method for selective quantification of tRNA charging. RNA (NEW YORK, N.Y.) 2022; 29:rna.079323.122. [PMID: 36283829 PMCID: PMC9808569 DOI: 10.1261/rna.079323.122] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/21/2022] [Accepted: 10/13/2022] [Indexed: 06/16/2023]
Abstract
Each transfer RNA (tRNA) is aminoacylated (charged) with a genetic codon-specific amino acid at its 3' end. Charged tRNAs are primarily used for translation, whereas fluctuations in charged tRNA fractions are known to reflect cellular response to stress. Here we report the development of individual tRNA-acylation using PCR (i-tRAP), a convenient PCR-based method that can specifically quantify individual tRNA charging ratio. In this i-tRAP method, demethylases remove base methylations which are problematic for reverse transcription reaction, and β-elimination reaction specifically removes the 3' end of adenine residue in uncharged tRNA. Subsequent TaqMan MGB qRT-PCR can distinguish between cDNA of charged tRNA and uncharged tRNA. By using this method, we revealed that the charging ratio of tRNAGln(CUG) was changed in response to amino acid starvation and also the charging ratio of tRNAGln(CUG) in senescent cells was lower than in young cells under starvation conditions. i-tRAP can be applicable to the quantification of charging ratio of various tRNAs, and provides a simple and convenient method for analyzing tRNA charging.
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Affiliation(s)
- Yusuke Tsukamoto
- National Institutes of Biomedical Innovation, Health and Nutrition (NIBIOHN)
| | - Yumi Nakamura
- National Institutes of Biomedical Innovation, Health and Nutrition (NIBIOHN)
| | - Makoto Hirata
- National Institutes of Biomedical Innovation, Health and Nutrition (NIBIOHN)
| | - Ryuichi Sakate
- National Institutes of Biomedical Innovation, Health and Nutrition (NIBIOHN)
| | - Tomonori Kimura
- National Institutes of Biomedical Innovation, Health and Nutrition (NIBIOHN)
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7
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Qi Q, Angermayr SA, Bollenbach T. Uncovering Key Metabolic Determinants of the Drug Interactions Between Trimethoprim and Erythromycin in Escherichia coli. Front Microbiol 2021; 12:760017. [PMID: 34745067 PMCID: PMC8564399 DOI: 10.3389/fmicb.2021.760017] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2021] [Accepted: 09/30/2021] [Indexed: 11/16/2022] Open
Abstract
Understanding interactions between antibiotics used in combination is an important theme in microbiology. Using the interactions between the antifolate drug trimethoprim and the ribosome-targeting antibiotic erythromycin in Escherichia coli as a model, we applied a transcriptomic approach for dissecting interactions between two antibiotics with different modes of action. When trimethoprim and erythromycin were combined, the transcriptional response of genes from the sulfate reduction pathway deviated from the dominant effect of trimethoprim on the transcriptome. We successfully altered the drug interaction from additivity to suppression by increasing the sulfate level in the growth environment and identified sulfate reduction as an important metabolic determinant that shapes the interaction between the two drugs. Our work highlights the potential of using prioritization of gene expression patterns as a tool for identifying key metabolic determinants that shape drug-drug interactions. We further demonstrated that the sigma factor-binding protein gene crl shapes the interactions between the two antibiotics, which provides a rare example of how naturally occurring variations between strains of the same bacterial species can sometimes generate very different drug interactions.
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Affiliation(s)
- Qin Qi
- Institute of Science and Technology Austria, Klosterneuburg, Austria.,Institute for Biological Physics, University of Cologne, Cologne, Germany
| | | | - Tobias Bollenbach
- Institute for Biological Physics, University of Cologne, Cologne, Germany.,Center for Data and Simulation Science, University of Cologne, Cologne, Germany
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8
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Pavlov MY, Ullman G, Ignatova Z, Ehrenberg M. Estimation of peptide elongation times from ribosome profiling spectra. Nucleic Acids Res 2021; 49:5124-5142. [PMID: 33885812 PMCID: PMC8136808 DOI: 10.1093/nar/gkab260] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2021] [Revised: 03/25/2021] [Accepted: 04/15/2021] [Indexed: 11/13/2022] Open
Abstract
Ribosome profiling spectra bear rich information on translation control and dynamics. Yet, due to technical biases in library generation, extracting quantitative measures of discrete translation events has remained elusive. Using maximum likelihood statistics and data set from Escherichia coli we develop a robust method for neutralizing technical biases (e.g. base specific RNase preferences in ribosome-protected mRNA fragments (RPF) generation), which allows for correct estimation of translation times at single codon resolution. Furthermore, we validated the method with available datasets from E. coli treated with antibiotic to inhibit isoleucyl-tRNA synthetase, and two datasets from Saccharomyces cerevisiae treated with two RNases with distinct cleavage signatures. We demonstrate that our approach accounts for RNase cleavage preferences and provides bias-corrected translation times estimates. Our approach provides a solution to the long-standing problem of extracting reliable information about peptide elongation times from highly noisy and technically biased ribosome profiling spectra.
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Affiliation(s)
- Michael Y Pavlov
- Department of Cell and Molecular Biology, Biomedical Center, University of Uppsala, 75237 Uppsala, Sweden
| | - Gustaf Ullman
- Department of Cell and Molecular Biology, Biomedical Center, University of Uppsala, 75237 Uppsala, Sweden
| | - Zoya Ignatova
- Institute for Biochemistry & Molecular Biology, University of Hamburg, 20146 Hamburg, Germany
| | - Måns Ehrenberg
- Department of Cell and Molecular Biology, Biomedical Center, University of Uppsala, 75237 Uppsala, Sweden
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9
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Román-Camacho JJ, Mauricio JC, Santos-Dueñas IM, García-Martínez T, García-García I. Functional metaproteomic analysis of alcohol vinegar microbiota during an acetification process: A quantitative proteomic approach. Food Microbiol 2021; 98:103799. [PMID: 33875225 DOI: 10.1016/j.fm.2021.103799] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2021] [Revised: 03/20/2021] [Accepted: 03/30/2021] [Indexed: 11/16/2022]
Abstract
Vinegar is elaborated using a semi-continuous submerged culture of a complex microbiota of acetic acid bacteria. The genus Komagataeibacter provides much of the proteins of the metaproteome, being K. europaeus the main species working in this environment. In this work, the protein profile of the vinegar microbiota, obtained by means of liquid chromatography-tandem mass spectrometry (LC-MS/MS) in samples from different cycle times of an acetification process using an alcohol medium, has been used to describe the functional metaproteome throughout the process. The analysis was focused on Komagataeibacter species which supplied about 90% of the metaproteome and particularly K. europaeus which accounts for more than 70%. According to these results, the natural behaviour of a microbial community in vinegar has been predicted at a quantitative proteomic level. The results revealed that most of the identified proteins involved in the metabolism of amino acids, biosynthesis of proteins, and energy production related-metabolic pathways increased their expression throughout the cycle loading phase and afterwards experimented a decrease coming into play other proteins acting against acetic acid stress. These findings may facilitate a better understanding of the microbiota's role and contributing to obtain a quality product.
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Affiliation(s)
- Juan J Román-Camacho
- Department of Agricultural Chemistry, Edaphology and Microbiology, Microbiology Area, Severo Ochoa Building (C6), Agrifood Campus of International Excellence ceiA3, University of Cordoba, Ctra. N-IV-A, Km 396, 14014, Córdoba, Spain.
| | - Juan C Mauricio
- Department of Agricultural Chemistry, Edaphology and Microbiology, Microbiology Area, Severo Ochoa Building (C6), Agrifood Campus of International Excellence ceiA3, University of Cordoba, Ctra. N-IV-A, Km 396, 14014, Córdoba, Spain.
| | - Inés M Santos-Dueñas
- Department of Inorganic Chemistry and Chemical Engineering, Chemical Engineering Area, Marie Curie Building (C3), Agrifood Campus of International Excellence ceiA3, University of Cordoba, Ctra. N-IV-A, Km 396, 14014, Córdoba, Spain.
| | - Teresa García-Martínez
- Department of Agricultural Chemistry, Edaphology and Microbiology, Microbiology Area, Severo Ochoa Building (C6), Agrifood Campus of International Excellence ceiA3, University of Cordoba, Ctra. N-IV-A, Km 396, 14014, Córdoba, Spain.
| | - Isidoro García-García
- Department of Inorganic Chemistry and Chemical Engineering, Chemical Engineering Area, Marie Curie Building (C3), Agrifood Campus of International Excellence ceiA3, University of Cordoba, Ctra. N-IV-A, Km 396, 14014, Córdoba, Spain.
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10
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Tian T, Li S, Lang P, Zhao D, Zeng J. Full-length ribosome density prediction by a multi-input and multi-output model. PLoS Comput Biol 2021; 17:e1008842. [PMID: 33770074 PMCID: PMC8026034 DOI: 10.1371/journal.pcbi.1008842] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2020] [Revised: 04/07/2021] [Accepted: 03/01/2021] [Indexed: 11/29/2022] Open
Abstract
Translation elongation is regulated by a series of complicated mechanisms in both prokaryotes and eukaryotes. Although recent advance in ribosome profiling techniques has enabled one to capture the genome-wide ribosome footprints along transcripts at codon resolution, the regulatory codes of elongation dynamics are still not fully understood. Most of the existing computational approaches for modeling translation elongation from ribosome profiling data mainly focus on local contextual patterns, while ignoring the continuity of the elongation process and relations between ribosome densities of remote codons. Modeling the translation elongation process in full-length coding sequence (CDS) level has not been studied to the best of our knowledge. In this paper, we developed a deep learning based approach with a multi-input and multi-output framework, named RiboMIMO, for modeling the ribosome density distributions of full-length mRNA CDS regions. Through considering the underlying correlations in translation efficiency among neighboring and remote codons and extracting hidden features from the input full-length coding sequence, RiboMIMO can greatly outperform the state-of-the-art baseline approaches and accurately predict the ribosome density distributions along the whole mRNA CDS regions. In addition, RiboMIMO explores the contributions of individual input codons to the predictions of output ribosome densities, which thus can help reveal important biological factors influencing the translation elongation process. The analyses, based on our interpretable metric named codon impact score, not only identified several patterns consistent with the previously-published literatures, but also for the first time (to the best of our knowledge) revealed that the codons located at a long distance from the ribosomal A site may also have an association on the translation elongation rate. This finding of long-range impact on translation elongation velocity may shed new light on the regulatory mechanisms of protein synthesis. Overall, these results indicated that RiboMIMO can provide a useful tool for studying the regulation of translation elongation in the range of full-length CDS. Translation elongation is a process in which amino acids are linked into proteins by ribosomes in cells. Translation elongation rates along the mRNAs are not constant, and are regulated by a series of mechanisms, such as codon rarity and mRNA stability. In this study, we modeled the translation elongation process at a full-length coding sequence level and developed a deep learning based approach to predict the translation elongation rates from mRNA sequences, through extracting the regulatory codes of elongation rates from the contextual sequences. The analyses, based on our interpretable metric named codon impact score, for the first time (to the best of our knowledge), revealed that in addition to the neighboring codons of the ribosomal A sites, the remote codons may also have an important impact on the translation elongation rates. This new finding may stimulate additional experiments and shed light on the regulatory mechanisms of protein synthesis.
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Affiliation(s)
- Tingzhong Tian
- Institute for Interdisciplinary Information Sciences, Tsinghua University, Beijing, China
| | - Shuya Li
- Institute for Interdisciplinary Information Sciences, Tsinghua University, Beijing, China
| | - Peng Lang
- Institute for Interdisciplinary Information Sciences, Tsinghua University, Beijing, China
| | - Dan Zhao
- Institute for Interdisciplinary Information Sciences, Tsinghua University, Beijing, China
- * E-mail: (DZ); (JZ)
| | - Jianyang Zeng
- Institute for Interdisciplinary Information Sciences, Tsinghua University, Beijing, China
- MOE Key Laboratory of Bioinformatics, Tsinghua University, Beijing, China
- * E-mail: (DZ); (JZ)
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11
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Kubyshkin V, Davis R, Budisa N. Biochemistry of fluoroprolines: the prospect of making fluorine a bioelement. Beilstein J Org Chem 2021; 17:439-460. [PMID: 33727970 PMCID: PMC7934785 DOI: 10.3762/bjoc.17.40] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2020] [Accepted: 01/22/2021] [Indexed: 12/12/2022] Open
Abstract
Due to the heterocyclic structure and distinct conformational profile, proline is unique in the repertoire of the 20 amino acids coded into proteins. Here, we summarize the biochemical work on the replacement of proline with (4R)- and (4S)-fluoroproline as well as 4,4-difluoroproline in proteins done mainly in the last two decades. We first recapitulate the complex position and biochemical fate of proline in the biochemistry of a cell, discuss the physicochemical properties of fluoroprolines, and overview the attempts to use these amino acids as proline replacements in studies of protein production and folding. Fluorinated proline replacements are able to elevate the protein expression speed and yields and improve the thermodynamic and kinetic folding profiles of individual proteins. In this context, fluoroprolines can be viewed as useful tools in the biotechnological toolbox. As a prospect, we envision that proteome-wide proline-to-fluoroproline substitutions could be possible. We suggest a hypothetical scenario for the use of laboratory evolutionary methods with fluoroprolines as a suitable vehicle to introduce fluorine into living cells. This approach may enable creation of synthetic cells endowed with artificial biodiversity, containing fluorine as a bioelement.
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Affiliation(s)
- Vladimir Kubyshkin
- Department of Chemistry, University of Manitoba, 144 Dysart Rd., Winnipeg, R3T 2N2, Canada
| | - Rebecca Davis
- Department of Chemistry, University of Manitoba, 144 Dysart Rd., Winnipeg, R3T 2N2, Canada
| | - Nediljko Budisa
- Department of Chemistry, University of Manitoba, 144 Dysart Rd., Winnipeg, R3T 2N2, Canada.,Institute of Chemistry, Technical University of Berlin, Müller-Breslau-Str. 10, 10623 Berlin, Germany
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12
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Schwark DG, Schmitt MA, Fisk JD. Directed Evolution of the Methanosarcina barkeri Pyrrolysyl tRNA/aminoacyl tRNA Synthetase Pair for Rapid Evaluation of Sense Codon Reassignment Potential. Int J Mol Sci 2021; 22:E895. [PMID: 33477414 PMCID: PMC7830368 DOI: 10.3390/ijms22020895] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2020] [Revised: 01/10/2021] [Accepted: 01/12/2021] [Indexed: 12/20/2022] Open
Abstract
Genetic code expansion has largely focused on the reassignment of amber stop codons to insert single copies of non-canonical amino acids (ncAAs) into proteins. Increasing effort has been directed at employing the set of aminoacyl tRNA synthetase (aaRS) variants previously evolved for amber suppression to incorporate multiple copies of ncAAs in response to sense codons in Escherichia coli. Predicting which sense codons are most amenable to reassignment and which orthogonal translation machinery is best suited to each codon is challenging. This manuscript describes the directed evolution of a new, highly efficient variant of the Methanosarcina barkeri pyrrolysyl orthogonal tRNA/aaRS pair that activates and incorporates tyrosine. The evolved M. barkeri tRNA/aaRS pair reprograms the amber stop codon with 98.1 ± 3.6% efficiency in E. coli DH10B, rivaling the efficiency of the wild-type tyrosine-incorporating Methanocaldococcus jannaschii orthogonal pair. The new orthogonal pair is deployed for the rapid evaluation of sense codon reassignment potential using our previously developed fluorescence-based screen. Measurements of sense codon reassignment efficiencies with the evolved M. barkeri machinery are compared with related measurements employing the M. jannaschii orthogonal pair system. Importantly, we observe different patterns of sense codon reassignment efficiency for the M. jannaschii tyrosyl and M. barkeri pyrrolysyl systems, suggesting that particular codons will be better suited to reassignment by different orthogonal pairs. A broad evaluation of sense codon reassignment efficiencies to tyrosine with the M. barkeri system will highlight the most promising positions at which the M. barkeri orthogonal pair may infiltrate the E. coli genetic code.
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Affiliation(s)
| | | | - John D. Fisk
- Department of Chemistry, University of Colorado Denver, Campus Box 194, P.O. Box 173364, Denver, CO 80217-3364, USA; (D.G.S.); (M.A.S.)
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13
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Sun X, Li Q, Wang Y, Zhou W, Guo Y, Chen J, Zheng P, Sun J, Ma Y. Isoleucyl-tRNA synthetase mutant based whole-cell biosensor for high-throughput selection of isoleucine overproducers. Biosens Bioelectron 2021; 172:112783. [PMID: 33157411 DOI: 10.1016/j.bios.2020.112783] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2020] [Revised: 10/29/2020] [Accepted: 10/30/2020] [Indexed: 02/02/2023]
Abstract
Whole-cell amino acid biosensors can sense the concentrations of certain amino acids and output easily detectable signals, which are important for construction of microbial producers. However, many reported biosensors have poor specificity because they also sense non-target amino acids. Besides, biosensors for many amino acids are still unavailable. In this study, we proposed a new strategy for constructing whole-cell biosensors based on aminoacyl-tRNA synthetases (aaRSs), which take the advantage of their universality and intrinsically specific binding ability to corresponding amino acids. Taking isoleucine biosensor as an example, we first mutated the isoleucyl-tRNA synthetase in Escherichia coli to dramatically decrease its affinity to isoleucine. The engineered cells specifically sensed isoleucine and output isoleucine dose-dependent cell growth as an easily detectable signal. To further expand the sensing range, an isoleucine exporter was overexpressed to enhance excretion of intracellular isoleucine. Since cells equipped with the optimized whole-cell biosensor showed accelerated growth when cells produced higher concentrations of isoleucine, the biosensor was successfully applied in high-throughput selection of isoleucine overproducers from random mutation libraries. This work demonstrates the feasibility of engineering aaRSs to construct a new kind of whole-cell biosensors for amino acids. Considering all twenty proteinogenic and many non-canonical amino acids have their specific aaRSs, this strategy should be useful for developing biosensors for various amino acids.
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Affiliation(s)
- Xue Sun
- Tianjin Institute of Industrial Biotechnology, Key Laboratory of Systems Microbial Biotechnology, Chinese Academy of Sciences, Tianjin 300308, China; National Technology Innovation Center of Synthetic Biology, Tianjin 300308, China; University of Chinese Academy of Sciences, Beijing 100049, China
| | - Qinggang Li
- Tianjin Institute of Industrial Biotechnology, Key Laboratory of Systems Microbial Biotechnology, Chinese Academy of Sciences, Tianjin 300308, China; National Technology Innovation Center of Synthetic Biology, Tianjin 300308, China
| | - Yu Wang
- Tianjin Institute of Industrial Biotechnology, Key Laboratory of Systems Microbial Biotechnology, Chinese Academy of Sciences, Tianjin 300308, China; National Technology Innovation Center of Synthetic Biology, Tianjin 300308, China
| | - Wenjuan Zhou
- Tianjin Institute of Industrial Biotechnology, Key Laboratory of Systems Microbial Biotechnology, Chinese Academy of Sciences, Tianjin 300308, China; National Technology Innovation Center of Synthetic Biology, Tianjin 300308, China
| | - Yanmei Guo
- Tianjin Institute of Industrial Biotechnology, Key Laboratory of Systems Microbial Biotechnology, Chinese Academy of Sciences, Tianjin 300308, China; National Technology Innovation Center of Synthetic Biology, Tianjin 300308, China
| | - Jiuzhou Chen
- Tianjin Institute of Industrial Biotechnology, Key Laboratory of Systems Microbial Biotechnology, Chinese Academy of Sciences, Tianjin 300308, China; National Technology Innovation Center of Synthetic Biology, Tianjin 300308, China
| | - Ping Zheng
- Tianjin Institute of Industrial Biotechnology, Key Laboratory of Systems Microbial Biotechnology, Chinese Academy of Sciences, Tianjin 300308, China; National Technology Innovation Center of Synthetic Biology, Tianjin 300308, China.
| | - Jibin Sun
- Tianjin Institute of Industrial Biotechnology, Key Laboratory of Systems Microbial Biotechnology, Chinese Academy of Sciences, Tianjin 300308, China; National Technology Innovation Center of Synthetic Biology, Tianjin 300308, China.
| | - Yanhe Ma
- Tianjin Institute of Industrial Biotechnology, Key Laboratory of Systems Microbial Biotechnology, Chinese Academy of Sciences, Tianjin 300308, China; National Technology Innovation Center of Synthetic Biology, Tianjin 300308, China
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14
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Liu Y, Yang Q, Zhao F. Synonymous but Not Silent: The Codon Usage Code for Gene Expression and Protein Folding. Annu Rev Biochem 2021; 90:375-401. [PMID: 33441035 DOI: 10.1146/annurev-biochem-071320-112701] [Citation(s) in RCA: 65] [Impact Index Per Article: 21.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Codon usage bias, the preference for certain synonymous codons, is found in all genomes. Although synonymous mutations were previously thought to be silent, a large body of evidence has demonstrated that codon usage can play major roles in determining gene expression levels and protein structures. Codon usage influences translation elongation speed and regulates translation efficiency and accuracy. Adaptation of codon usage to tRNA expression determines the proteome landscape. In addition, codon usage biases result in nonuniform ribosome decoding rates on mRNAs, which in turn influence the cotranslational protein folding process that is critical for protein function in diverse biological processes. Conserved genome-wide correlations have also been found between codon usage and protein structures. Furthermore, codon usage is a major determinant of mRNA levels through translation-dependent effects on mRNA decay and translation-independent effects on transcriptional and posttranscriptional processes. Here, we discuss the multifaceted roles and mechanisms of codon usage in different gene regulatory processes.
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Affiliation(s)
- Yi Liu
- Department of Physiology, University of Texas Southwestern Medical Center, Dallas, Texas 75390-9040, USA;
| | - Qian Yang
- Department of Physiology, University of Texas Southwestern Medical Center, Dallas, Texas 75390-9040, USA;
| | - Fangzhou Zhao
- Department of Physiology, University of Texas Southwestern Medical Center, Dallas, Texas 75390-9040, USA;
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15
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Abstract
Translation is a central biological process in living cells. Ribosome profiling approach enables assessing translation on a global, cell-wide level. Extracting versatile information from the ribosome profiling data usually requires specialized expertise for handling the sequencing data that is not available to the broad community of experimentalists. Here, we provide an easy-to-use and modifiable workflow that uses a small set of commands and enables full data analysis in a standardized way, including precise positioning of the ribosome-protected fragments, for determining codon-specific translation features. The workflow is complemented with simple step-by-step explanations and is accessible to scientists with no computational background.
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Affiliation(s)
| | - Zoya Ignatova
- Institute for Biochemistry and Molecular Biology, Department of Chemistry, University of Hamburg, Hamburg, Germany.
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16
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Ayan GB, Park HJ, Gallie J. The birth of a bacterial tRNA gene by large-scale, tandem duplication events. eLife 2020; 9:57947. [PMID: 33124983 PMCID: PMC7661048 DOI: 10.7554/elife.57947] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2020] [Accepted: 10/29/2020] [Indexed: 12/20/2022] Open
Abstract
Organisms differ in the types and numbers of tRNA genes that they carry. While the evolutionary mechanisms behind tRNA gene set evolution have been investigated theoretically and computationally, direct observations of tRNA gene set evolution remain rare. Here, we report the evolution of a tRNA gene set in laboratory populations of the bacterium Pseudomonas fluorescens SBW25. The growth defect caused by deleting the single-copy tRNA gene, serCGA, is rapidly compensated by large-scale (45–290 kb) duplications in the chromosome. Each duplication encompasses a second, compensatory tRNA gene (serTGA) and is associated with a rise in tRNA-Ser(UGA) in the mature tRNA pool. We postulate that tRNA-Ser(CGA) elimination increases the translational demand for tRNA-Ser(UGA), a pressure relieved by increasing serTGA copy number. This work demonstrates that tRNA gene sets can evolve through duplication of existing tRNA genes, a phenomenon that may contribute to the presence of multiple, identical tRNA gene copies within genomes.
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Affiliation(s)
- Gökçe B Ayan
- Department of Evolutionary Theory, Max Planck Institute for Evolutionary Biology, Plön, Germany
| | - Hye Jin Park
- Department of Evolutionary Theory, Max Planck Institute for Evolutionary Biology, Plön, Germany.,Asia Pacific Center for Theoretical Physics, Pohang, Republic of Korea
| | - Jenna Gallie
- Department of Evolutionary Theory, Max Planck Institute for Evolutionary Biology, Plön, Germany
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17
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Ovchinnikov SV, Bikmetov D, Livenskyi A, Serebryakova M, Wilcox B, Mangano K, Shiriaev DI, Osterman IA, Sergiev PV, Borukhov S, Vazquez-Laslop N, Mankin AS, Severinov K, Dubiley S. Mechanism of translation inhibition by type II GNAT toxin AtaT2. Nucleic Acids Res 2020; 48:8617-8625. [PMID: 32597957 PMCID: PMC7470980 DOI: 10.1093/nar/gkaa551] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2020] [Revised: 06/05/2020] [Accepted: 06/17/2020] [Indexed: 12/25/2022] Open
Abstract
Type II toxin–antitoxins systems are widespread in prokaryotic genomes. Typically, they comprise two proteins, a toxin, and an antitoxin, encoded by adjacent genes and forming a complex in which the enzymatic activity of the toxin is inhibited. Under stress conditions, the antitoxin is degraded liberating the active toxin. Though thousands of various toxin–antitoxins pairs have been predicted bioinformatically, only a handful has been thoroughly characterized. Here, we describe the AtaT2 toxin from a toxin–antitoxin system from Escherichia coli O157:H7. We show that AtaT2 is the first GNAT (Gcn5-related N-acetyltransferase) toxin that specifically targets charged glycyl tRNA. In vivo, the AtaT2 activity induces ribosome stalling at all four glycyl codons but does not evoke a stringent response. In vitro, AtaT2 acetylates the aminoacyl moiety of isoaccepting glycyl tRNAs, thus precluding their participation in translation. Our study broadens the known target specificity of GNAT toxins beyond the earlier described isoleucine and formyl methionine tRNAs, and suggest that various GNAT toxins may have evolved to specificaly target other if not all individual aminoacyl tRNAs.
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Affiliation(s)
- Stepan V Ovchinnikov
- Centre for Life Sciences, Skolkovo Institute of Science and Technology, Skolkovo 143025, Russia
| | - Dmitry Bikmetov
- Center for Precision Genome Editing and Genetic Technologies for Biomedicine, Institute of Gene Biology, Russian Academy of Sciences, 119334 Moscow, Russia.,Institute of Gene Biology, Russian Academy of Science, 119334 Moscow, Russia
| | - Alexei Livenskyi
- Institute of Gene Biology, Russian Academy of Science, 119334 Moscow, Russia.,Faculty of Bioengineering and Bioinformatics, Lomonosov Moscow State University, Moscow 119992, Russia
| | - Marina Serebryakova
- Institute of Gene Biology, Russian Academy of Science, 119334 Moscow, Russia.,Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Moscow 119992, Russia
| | - Brendan Wilcox
- Centre for Life Sciences, Skolkovo Institute of Science and Technology, Skolkovo 143025, Russia
| | - Kyle Mangano
- Center for Biomolecular Sciences, University of Illinois, Chicago, IL 60607, USA.,Department of Pharmaceutical Sciences, University of Illinois, Chicago, IL 60607, USA
| | - Dmitrii I Shiriaev
- Department of Chemistry, Lomonosov Moscow State University, Moscow 119992, Russia
| | - Ilya A Osterman
- Centre for Life Sciences, Skolkovo Institute of Science and Technology, Skolkovo 143025, Russia.,Department of Chemistry, Lomonosov Moscow State University, Moscow 119992, Russia
| | - Petr V Sergiev
- Centre for Life Sciences, Skolkovo Institute of Science and Technology, Skolkovo 143025, Russia.,Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Moscow 119992, Russia
| | - Sergei Borukhov
- Department of Cell Biology and Neuroscience, Rowan University School of Osteopathic Medicine, Stratford, NJ 08084-1489, USA
| | - Nora Vazquez-Laslop
- Center for Biomolecular Sciences, University of Illinois, Chicago, IL 60607, USA.,Department of Pharmaceutical Sciences, University of Illinois, Chicago, IL 60607, USA
| | - Alexander S Mankin
- Center for Biomolecular Sciences, University of Illinois, Chicago, IL 60607, USA.,Department of Pharmaceutical Sciences, University of Illinois, Chicago, IL 60607, USA
| | - Konstantin Severinov
- Centre for Life Sciences, Skolkovo Institute of Science and Technology, Skolkovo 143025, Russia.,Center for Precision Genome Editing and Genetic Technologies for Biomedicine, Institute of Gene Biology, Russian Academy of Sciences, 119334 Moscow, Russia.,Waksman Institute for Microbiology, Piscataway, NJ 08854-8020, USA
| | - Svetlana Dubiley
- Centre for Life Sciences, Skolkovo Institute of Science and Technology, Skolkovo 143025, Russia.,Institute of Gene Biology, Russian Academy of Science, 119334 Moscow, Russia
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18
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Gamper H, Hou YM. A Label-Free Assay for Aminoacylation of tRNA. Genes (Basel) 2020; 11:genes11101173. [PMID: 33036365 PMCID: PMC7601589 DOI: 10.3390/genes11101173] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2020] [Revised: 09/28/2020] [Accepted: 10/01/2020] [Indexed: 12/16/2022] Open
Abstract
Aminoacylation of tRNA generates an aminoacyl-tRNA (aa-tRNA) that is active for protein synthesis on the ribosome. Quantification of aminoacylation of tRNA is critical to understand the mechanism of specificity and the flux of the aa-tRNA into the protein synthesis machinery, which determines the rate of cell growth. Traditional assays for the quantification of tRNA aminoacylation involve radioactivity, either with a radioactive amino acid or with a [3′-32P]-labeled tRNA. We describe here a label-free assay that monitors aminoacylation by biotinylation-streptavidin (SA) conjugation to the α-amine or the α-imine of the aminoacyl group on the aa-tRNA. The conjugated aa-tRNA product is readily separated from the unreacted tRNA by a denaturing polyacrylamide gel, allowing for quantitative measurement of aminoacylation. This label-free assay is applicable to a wide range of amino acids and tRNA sequences and to both classes of aminoacylation. It is more sensitive and robust than the assay with a radioactive amino acid and has the potential to explore a wider range of tRNA than the assay with a [3′-32P]-labeled tRNA. This label-free assay reports kinetic parameters of aminoacylation quantitatively similar to those reported by using a radioactive amino acid, suggesting its broad applicability to research relevant to human health and disease.
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19
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Parker DJ, Lalanne JB, Kimura S, Johnson GE, Waldor MK, Li GW. Growth-Optimized Aminoacyl-tRNA Synthetase Levels Prevent Maximal tRNA Charging. Cell Syst 2020; 11:121-130.e6. [PMID: 32726597 DOI: 10.1016/j.cels.2020.07.005] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2019] [Revised: 05/07/2020] [Accepted: 07/02/2020] [Indexed: 01/28/2023]
Abstract
Aminoacyl-tRNA synthetases (aaRSs) serve a dual role in charging tRNAs. Their enzymatic activities both provide protein synthesis flux and reduce uncharged tRNA levels. Although uncharged tRNAs can negatively impact bacterial growth, substantial concentrations of tRNAs remain deacylated even under nutrient-rich conditions. Here, we show that tRNA charging in Bacillus subtilis is not maximized due to optimization of aaRS production during rapid growth, which prioritizes demands in protein synthesis over charging levels. The presence of uncharged tRNAs is alleviated by precisely tuned translation kinetics and the stringent response, both insensitive to aaRS overproduction but sharply responsive to underproduction, allowing for just enough aaRS production atop a "fitness cliff." Notably, we find that the stringent response mitigates fitness defects at all aaRS underproduction levels even without external starvation. Thus, adherence to minimal, flux-satisfying protein production drives limited tRNA charging and provides a basis for the sensitivity and setpoints of an integrated growth-control network.
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Affiliation(s)
- Darren J Parker
- Department of Biology, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Jean-Benoît Lalanne
- Department of Biology, Massachusetts Institute of Technology, Cambridge, MA 02139, USA; Department of Physics, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Satoshi Kimura
- Division of Infectious Diseases, Brigham and Women's Hospital, Boston, MA 02115, USA; Department of Microbiology, Harvard Medical School, Boston, MA 02115, USA; Howard Hughes Medical Institute, Harvard Medical School, Boston, MA 02115, USA
| | - Grace E Johnson
- Department of Biology, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Matthew K Waldor
- Division of Infectious Diseases, Brigham and Women's Hospital, Boston, MA 02115, USA; Department of Microbiology, Harvard Medical School, Boston, MA 02115, USA; Howard Hughes Medical Institute, Harvard Medical School, Boston, MA 02115, USA
| | - Gene-Wei Li
- Department of Biology, Massachusetts Institute of Technology, Cambridge, MA 02139, USA.
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20
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Avcilar-Kucukgoze I, Gamper H, Polte C, Ignatova Z, Kraetzner R, Shtutman M, Hou YM, Dong DW, Kashina A. tRNA Arg-Derived Fragments Can Serve as Arginine Donors for Protein Arginylation. Cell Chem Biol 2020; 27:839-849.e4. [PMID: 32553119 DOI: 10.1016/j.chembiol.2020.05.013] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2020] [Revised: 03/12/2020] [Accepted: 05/27/2020] [Indexed: 12/23/2022]
Abstract
Arginyltransferase ATE1 mediates posttranslational arginylation and plays key roles in multiple physiological processes. ATE1 utilizes arginyl (Arg)-tRNAArg as the donor of Arg, putting this reaction into a direct competition with the protein synthesis machinery. Here, we address the question of ATE1- Arg-tRNAArg specificity as a potential mechanism enabling this competition in vivo. Using in vitro arginylation assays and Ate1 knockout models, we find that, in addition to full-length tRNA, ATE1 is also able to utilize short tRNAArg fragments that bear structural resemblance to tRNA-derived fragments (tRF), a recently discovered class of small regulatory non-coding RNAs with global emerging biological role. Ate1 knockout cells show a decrease in tRFArg generation and a significant increase in the ratio of tRNAArg:tRFArg compared with wild type, suggesting a functional link between tRFArg and arginylation. We propose that generation of physiologically important tRFs can serve as a switch between translation and protein arginylation.
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Affiliation(s)
- Irem Avcilar-Kucukgoze
- Department of Biomedical Sciences, School of Veterinary Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Howard Gamper
- Department of Biochemistry and Molecular Biology, Thomas Jefferson University, Philadelphia, PA 19144, USA
| | - Christine Polte
- Institute of Biochemistry and Molecular Biology, University of Hamburg, 20148 Hamburg, Germany
| | - Zoya Ignatova
- Institute of Biochemistry and Molecular Biology, University of Hamburg, 20148 Hamburg, Germany
| | - Ralph Kraetzner
- Department of Pediatrics and Adolescent Medicine, University Medical Center Göttingen, 37075 Göttingen, Germany
| | - Michael Shtutman
- Department of Drug Discovery and Biomedical Sciences, College of Pharmacy, University of South Carolina, Columbia, SC 29208, USA
| | - Ya-Ming Hou
- Department of Biochemistry and Molecular Biology, Thomas Jefferson University, Philadelphia, PA 19144, USA
| | - Dawei W Dong
- Department of Biomedical Sciences, School of Veterinary Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA; Institute for Biomedical Informatics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Anna Kashina
- Department of Biomedical Sciences, School of Veterinary Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA.
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21
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Maser A, Peebo K, Vilu R, Nahku R. Amino acids are key substrates to Escherichia coli BW25113 for achieving high specific growth rate. Res Microbiol 2020; 171:185-193. [PMID: 32057959 DOI: 10.1016/j.resmic.2020.02.001] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2019] [Revised: 02/02/2020] [Accepted: 02/04/2020] [Indexed: 12/30/2022]
Abstract
Studying substrate consumption in nutrient-rich conditions is challenging because often the growth medium includes undefined components like yeast extract or peptone. For clear and consistent results, it is necessary to use defined medium, where substrate utilization can be followed. In the present work, Escherichia coli BW25113 batch growth in a medium supplemented with 20 proteinogenic amino acids and glucose was studied. Focus was on the quantitative differences in substrate consumption and proteome composition between minimal and nutrient-rich medium. In the latter, 72% of carbon used for biomass growth came from amino acids and 28% from glucose. Serine was identified as the most consumed substrate with 41% of total carbon consumption. Proteome comparison between nutrient-rich and minimal medium revealed changes in TCA cycle and acetate producing enzymes that together with extracellular metabolite data pointed to serine being consumed mainly for energy generation purposes. Serine removal from the growth medium decreased specific growth rate by 22%. In addition, proteome comparison between media revealed a large shift in amino acid synthesis and translation related proteins. Overall, this work describes in quantitative terms the batch growth carbon uptake profile and proteome allocation of E. coli BW25113 in minimal and nutrient-rich medium.
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Affiliation(s)
- Andres Maser
- Tallinn University of Technology, Department of Chemistry and Biotechnology, Akadeemia tee 15, 12618 Tallinn, Estonia; Center of Food and Fermentation Technologies, Akadeemia tee 15a, 12618 Tallinn, Estonia.
| | - Karl Peebo
- Tallinn University of Technology, Department of Chemistry and Biotechnology, Akadeemia tee 15, 12618 Tallinn, Estonia; Center of Food and Fermentation Technologies, Akadeemia tee 15a, 12618 Tallinn, Estonia
| | - Raivo Vilu
- Tallinn University of Technology, Department of Chemistry and Biotechnology, Akadeemia tee 15, 12618 Tallinn, Estonia; Center of Food and Fermentation Technologies, Akadeemia tee 15a, 12618 Tallinn, Estonia
| | - Ranno Nahku
- Center of Food and Fermentation Technologies, Akadeemia tee 15a, 12618 Tallinn, Estonia.
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22
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Planson AG, Sauveplane V, Dervyn E, Jules M. Bacterial growth physiology and RNA metabolism. BIOCHIMICA ET BIOPHYSICA ACTA-GENE REGULATORY MECHANISMS 2020; 1863:194502. [PMID: 32044462 DOI: 10.1016/j.bbagrm.2020.194502] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Received: 11/29/2019] [Revised: 01/17/2020] [Accepted: 02/06/2020] [Indexed: 12/31/2022]
Abstract
Bacteria are sophisticated systems with high capacity and flexibility to adapt to various environmental conditions. Each prokaryote however possesses a defined metabolic network, which sets its overall metabolic capacity, and therefore the maximal growth rate that can be reached. To achieve optimal growth, bacteria adopt various molecular strategies to optimally adjust gene expression and optimize resource allocation according to the nutrient availability. The resulting physiological changes are often accompanied by changes in the growth rate, and by global regulation of gene expression. The growth-rate-dependent variation of the abundances in the cellular machineries, together with condition-specific regulatory mechanisms, affect RNA metabolism and fate and pose a challenge for rational gene expression reengineering of synthetic circuits. This article is part of a Special Issue entitled: RNA and gene control in bacteria, edited by Dr. M. Guillier and F. Repoila.
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Affiliation(s)
- Anne-Gaëlle Planson
- Université Paris-Saclay, INRAE, AgroParisTech, Micalis Institute, 78350 Jouy-en-Josas, France.
| | - Vincent Sauveplane
- Université Paris-Saclay, INRAE, AgroParisTech, Micalis Institute, 78350 Jouy-en-Josas, France.
| | - Etienne Dervyn
- Université Paris-Saclay, INRAE, AgroParisTech, Micalis Institute, 78350 Jouy-en-Josas, France.
| | - Matthieu Jules
- Université Paris-Saclay, INRAE, AgroParisTech, Micalis Institute, 78350 Jouy-en-Josas, France.
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23
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Czech A. Deep sequencing of tRNA's 3'-termini sheds light on CCA-tail integrity and maturation. RNA (NEW YORK, N.Y.) 2020; 26:199-208. [PMID: 31719125 PMCID: PMC6961547 DOI: 10.1261/rna.072330.119] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/18/2019] [Accepted: 11/07/2019] [Indexed: 06/10/2023]
Abstract
The 3'-termini of tRNA are the point of amino acid linkage and thus crucial for their function in delivering amino acids to the ribosome and other enzymes. Therefore, to provide tRNA functionality, cells have to ensure the integrity of the 3'-terminal CCA-tail, which is generated during maturation by the 3'-trailer processing machinery and maintained by the CCA-adding enzyme. We developed a new tRNA sequencing method that is specifically tailored to assess the 3'-termini of E. coli tRNA. Intriguingly, we found a significant fraction of tRNAs with damaged CCA-tails under exponential growth conditions and, surprisingly, this fraction decreased upon transition into stationary phase. Interestingly, tRNAs bearing guanine as a discriminator base are generally unaffected by CCA-tail damage. In addition, we showed tRNA species-specific 3'-trailer processing patterns and reproduced in vitro findings on preferences of the maturation enzyme RNase T in vivo.
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Affiliation(s)
- Andreas Czech
- Institute of Biochemistry and Molecular Biology, Chemistry Department, University of Hamburg, 20146 Hamburg, Germany
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24
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Hughes CE, Coody TK, Jeong MY, Berg JA, Winge DR, Hughes AL. Cysteine Toxicity Drives Age-Related Mitochondrial Decline by Altering Iron Homeostasis. Cell 2020; 180:296-310.e18. [PMID: 31978346 PMCID: PMC7164368 DOI: 10.1016/j.cell.2019.12.035] [Citation(s) in RCA: 109] [Impact Index Per Article: 27.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2019] [Revised: 11/06/2019] [Accepted: 12/23/2019] [Indexed: 12/21/2022]
Abstract
Mitochondria and lysosomes are functionally linked, and their interdependent decline is a hallmark of aging and disease. Despite the long-standing connection between these organelles, the function(s) of lysosomes required to sustain mitochondrial health remains unclear. Here, working in yeast, we show that the lysosome-like vacuole maintains mitochondrial respiration by spatially compartmentalizing amino acids. Defects in vacuole function result in a breakdown in intracellular amino acid homeostasis, which drives age-related mitochondrial decline. Among amino acids, we find that cysteine is most toxic for mitochondria and show that elevated non-vacuolar cysteine impairs mitochondrial respiration by limiting intracellular iron availability through an oxidant-based mechanism. Cysteine depletion or iron supplementation restores mitochondrial health in vacuole-impaired cells and prevents mitochondrial decline during aging. These results demonstrate that cysteine toxicity is a major driver of age-related mitochondrial deterioration and identify vacuolar amino acid compartmentation as a cellular strategy to minimize amino acid toxicity.
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Affiliation(s)
- Casey E Hughes
- Department of Biochemistry, University of Utah School of Medicine, Salt Lake City, UT 84112, USA
| | - Troy K Coody
- Department of Biochemistry, University of Utah School of Medicine, Salt Lake City, UT 84112, USA
| | - Mi-Young Jeong
- Department of Biochemistry, University of Utah School of Medicine, Salt Lake City, UT 84112, USA; Department of Medicine, University of Utah School of Medicine, Salt Lake City, UT 84112, USA
| | - Jordan A Berg
- Department of Biochemistry, University of Utah School of Medicine, Salt Lake City, UT 84112, USA
| | - Dennis R Winge
- Department of Biochemistry, University of Utah School of Medicine, Salt Lake City, UT 84112, USA; Department of Medicine, University of Utah School of Medicine, Salt Lake City, UT 84112, USA
| | - Adam L Hughes
- Department of Biochemistry, University of Utah School of Medicine, Salt Lake City, UT 84112, USA.
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25
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Alanyl-tRNA Synthetase Quality Control Prevents Global Dysregulation of the Escherichia coli Proteome. mBio 2019; 10:mBio.02921-19. [PMID: 31848288 PMCID: PMC6918089 DOI: 10.1128/mbio.02921-19] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
Mechanisms have evolved to prevent errors in replication, transcription, and translation of genetic material, with translational errors occurring most frequently. Errors in protein synthesis can occur at two steps, during tRNA aminoacylation and ribosome decoding. Recent advances in protein mass spectrometry have indicated that previous reports of translational errors have potentially underestimated the frequency of these events, but also that the majority of translational errors occur during ribosomal decoding, suggesting that aminoacylation errors are evolutionarily less tolerated. Despite that interpretation, there is evidence that some aminoacylation errors may be regulated, and thus provide a benefit to the cell, while others are clearly detrimental. Here, we show that while it has been suggested that regulated Thr-to-Ser substitutions may be beneficial, there is a threshold beyond which these errors are detrimental. In contrast, we show that errors mediated by alanyl-tRNA synthetase (AlaRS) are not well tolerated and induce a global stress response that leads to gross perturbation of the Escherichia coli proteome, with potentially catastrophic effects on fitness and viability. Tolerance for Ala mistranslation appears to be much lower than with other translational errors, consistent with previous reports of multiple proofreading mechanisms targeting mischarged tRNAAla These results demonstrate the essential role of aminoacyl-tRNA proofreading in optimizing cellular fitness and suggest that any potentially beneficial effects of mistranslation may be confined to specific amino acid substitutions.IMPORTANCE Errors in protein synthesis have historically been assumed to be detrimental to the cell. While there are many reports that translational errors are consequential, there is a growing body of evidence that some mistranslation events may be tolerated or even beneficial. Using two models of mistranslation, we compare the direct phenotypic effects of these events in Escherichia coli This work provides insight into the threshold for tolerance of specific mistranslation events that were previously predicted to be broadly neutral to proteome integrity. Furthermore, these data reveal the effects of mistranslation beyond the general unfolded stress response, leading to global translational reprogramming.
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Kriner MA, Subramaniam AR. The serine transporter SdaC prevents cell lysis upon glucose depletion in Escherichia coli. Microbiologyopen 2019; 9:e960. [PMID: 31680488 PMCID: PMC7002108 DOI: 10.1002/mbo3.960] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2019] [Revised: 09/25/2019] [Accepted: 10/09/2019] [Indexed: 11/10/2022] Open
Abstract
The amino acid serine plays diverse metabolic roles, yet bacteria actively degrade exogenously provided serine via deamination to pyruvate. Serine deamination is thought to be a detoxification mechanism due to the ability of serine to inhibit several biosynthetic reactions, but this pathway remains highly active even in nutrient-replete conditions. While investigating the physiological roles of serine deamination in different growth conditions, we discovered that Escherichia coli cells lacking the sdaCB operon, which encodes the serine transporter SdaC and the serine deaminase SdaB, lyse upon glucose depletion in a medium containing no exogenous serine but all other amino acids and nucleobases. Unexpectedly, this lysis phenotype can be recapitulated by deleting sdaC alone and can be rescued by heterologous expression of SdaC. Lysis of ΔsdaC cells can be prevented by omitting glycine from the medium, inhibiting the glycine cleavage system, or by increasing alanine availability. Together, our results reveal that the serine transporter SdaC plays a critical role in maintaining amino acid homeostasis during shifts in nutrient availability in E. coli.
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Affiliation(s)
- Michelle A Kriner
- Basic Sciences Division and Computational Biology Section of the Public Health Sciences Division, Fred Hutchinson Cancer Research Center, Seattle, WA, USA
| | - Arvind R Subramaniam
- Basic Sciences Division and Computational Biology Section of the Public Health Sciences Division, Fred Hutchinson Cancer Research Center, Seattle, WA, USA
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27
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Polymerase III transcription is necessary for T cell priming by dendritic cells. Proc Natl Acad Sci U S A 2019; 116:22721-22729. [PMID: 31636192 DOI: 10.1073/pnas.1904396116] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023] Open
Abstract
Exposure to microbe-associated molecular patterns (MAMPs) causes dendritic cells (DCs) to undergo a remarkable activation process characterized by changes in key biochemical mechanisms. These enhance antigen processing and presentation, as well as strengthen DC capacity to stimulate naïve T cell proliferation. Here, we show that in response to the MAMPS lipopolysaccharide and polyriboinosinic:polyribocytidylic acid (Poly I:C), RNA polymerase III (Pol lII)-dependent transcription and consequently tRNA gene expression are strongly induced in DCs. This is in part caused by the phosphorylation and nuclear export of MAF1 homolog negative regulator of Poll III (MAF1), via a synergistic casein kinase 2 (CK2)- and mammalian target of rapamycin-dependent signaling cascade downstream of Toll-like receptors (TLRs). De novo tRNA expression is necessary to augment protein synthesis and compensate for tRNA degradation driven by TLR-dependent DC exposure to type-I IFN. Although protein synthesis is not strongly inhibited in absence of RNA Pol III activity, it compromises the translation of key DC mRNAs, like those coding for costimulatory molecules and proinflammatory cytokines, which instead can be stored in stress granules, as shown for CD86 mRNA. TLR-dependent CK2 stimulation and subsequent RNA Pol III activation are therefore key for the acquisition by DCs of their unique T cell immune-stimulatory functions.
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28
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CD98hc (SLC3A2) sustains amino acid and nucleotide availability for cell cycle progression. Sci Rep 2019; 9:14065. [PMID: 31575908 PMCID: PMC6773781 DOI: 10.1038/s41598-019-50547-9] [Citation(s) in RCA: 27] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2019] [Accepted: 09/13/2019] [Indexed: 12/13/2022] Open
Abstract
CD98 heavy chain (CD98hc) forms heteromeric amino acid (AA) transporters by interacting with different light chains. Cancer cells overexpress CD98hc-transporters in order to meet their increased nutritional and antioxidant demands, since they provide branched-chain AA (BCAA) and aromatic AA (AAA) availability while protecting cells from oxidative stress. Here we show that BCAA and AAA shortage phenocopies the inhibition of mTORC1 signalling, protein synthesis and cell proliferation caused by CD98hc ablation. Furthermore, our data indicate that CD98hc sustains glucose uptake and glycolysis, and, as a consequence, the pentose phosphate pathway (PPP). Thus, loss of CD98hc triggers a dramatic reduction in the nucleotide pool, which leads to replicative stress in these cells, as evidenced by the enhanced DNA Damage Response (DDR), S-phase delay and diminished rate of mitosis, all recovered by nucleoside supplementation. In addition, proper BCAA and AAA availability sustains the expression of the enzyme ribonucleotide reductase. In this regard, BCAA and AAA shortage results in decreased content of deoxynucleotides that triggers replicative stress, also recovered by nucleoside supplementation. On the basis of our findings, we conclude that CD98hc plays a central role in AA and glucose cellular nutrition, redox homeostasis and nucleotide availability, all key for cell proliferation.
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Tameire F, Verginadis II, Leli NM, Polte C, Conn CS, Ojha R, Salas Salinas C, Chinga F, Monroy AM, Fu W, Wang P, Kossenkov A, Ye J, Amaravadi RK, Ignatova Z, Fuchs SY, Diehl JA, Ruggero D, Koumenis C. ATF4 couples MYC-dependent translational activity to bioenergetic demands during tumour progression. Nat Cell Biol 2019; 21:889-899. [PMID: 31263264 PMCID: PMC6608727 DOI: 10.1038/s41556-019-0347-9] [Citation(s) in RCA: 135] [Impact Index Per Article: 27.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2018] [Accepted: 05/22/2019] [Indexed: 12/20/2022]
Abstract
The c-Myc oncogene (MYC) drives malignant progression, but also induces robust anabolic and proliferative programs leading to intrinsic stress. The mechanisms enabling adaptation to MYC-induced stress are not fully understood. We have uncovered an essential role for the transcription factor ATF4 in survival following MYC activation. MYC upregulates ATF4 by activating GCN2 kinase through uncharged tRNAs. Subsequently, ATF4 co-occupies promoter regions of over 30 MYC target genes, primarily those regulating amino acid and protein synthesis, including 4E-BP1, a negative regulator of translation. 4E-BP1 is essential to balance protein synthesis, relieving MYC-induced proteotoxic stress. 4E-BP1 activity is negatively regulated by mTORC1-dependent phosphorylation and inhibition of mTORC1 signaling rescues ATF4 deficient cells from MYC-induced ER stress. Acute deletion of ATF4 significantly delays MYC-driven tumor progression and increases survival in mouse models. Our results establish ATF4 as a cellular rheostat of MYC-activity, ensuring enhanced translation rates are compatible with survival and tumor progression.
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Affiliation(s)
- Feven Tameire
- Department of Radiation Oncology, The Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Ioannis I Verginadis
- Department of Radiation Oncology, The Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Nektaria Maria Leli
- Department of Radiation Oncology, The Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Christine Polte
- Institute for Biochemistry and Molecular Biology, University of Hamburg, Hamburg, Germany
| | - Crystal S Conn
- School of Medicine and Department of Urology, Helen Diller Family Comprehensive Cancer Center, University of California, San Francisco, San Francisco, CA, USA
| | - Rani Ojha
- Abramson Cancer Center and Department of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Carlo Salas Salinas
- Department of Radiation Oncology, The Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Frank Chinga
- Department of Radiation Oncology, The Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Alexandra M Monroy
- Department of Radiation Oncology, The Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Weixuan Fu
- Penn Bioinformatics Core, Institute for Biomedical Informatics, University of Pennsylvania, Philadelphia, PA, USA
| | - Paul Wang
- Penn Bioinformatics Core, Institute for Biomedical Informatics, University of Pennsylvania, Philadelphia, PA, USA
| | - Andrew Kossenkov
- Center for Chemical Biology and Translational Medicine, The Wistar Institute, Philadelphia, PA, USA
| | - Jiangbin Ye
- Department of Radiation Oncology, Stanford University School of Medicine, Stanford, CA, USA
| | - Ravi K Amaravadi
- Abramson Cancer Center and Department of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Zoya Ignatova
- Institute for Biochemistry and Molecular Biology, University of Hamburg, Hamburg, Germany
| | - Serge Y Fuchs
- Department of Biomedical Sciences, School of Veterinary Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - J Alan Diehl
- Department of Biochemistry and Molecular Biology and Hollings Cancer Center, Medical University of South Carolina, Charleston, SC, USA
| | - Davide Ruggero
- School of Medicine and Department of Urology, Helen Diller Family Comprehensive Cancer Center, University of California, San Francisco, San Francisco, CA, USA
| | - Constantinos Koumenis
- Department of Radiation Oncology, The Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA.
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30
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An improved estimation of tRNA expression to better elucidate the coevolution between tRNA abundance and codon usage in bacteria. Sci Rep 2019; 9:3184. [PMID: 30816249 PMCID: PMC6395768 DOI: 10.1038/s41598-019-39369-x] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2018] [Accepted: 01/23/2019] [Indexed: 12/16/2022] Open
Abstract
The degree to which codon usage can be explained by tRNA abundance in bacterial species is often inadequate, partly because differential tRNA abundance is often approximated by tRNA copy numbers. To better understand the coevolution between tRNA abundance and codon usage, we provide a better estimate of tRNA abundance by profiling tRNA mapped reads (tRNA tpm) using publicly available RNA Sequencing data. To emphasize the feasibility of our approach, we demonstrate that tRNA tpm is consistent with tRNA abundances derived from RNA fingerprinting experiments in Escherichia coli, Bacillus subtilis, and Salmonella enterica. Furthermore, we do not observe an appreciable reduction in tRNA sequencing efficiency due to post-transcriptional methylations in the seven bacteria studied. To determine optimal codons, we calculate codon usage in highly and lowly expressed genes determined by protein per transcript. We found that tRNA tpm is sensitive to identify more translationally optimal codons than gene copy number and early tRNA fingerprinting abundances. Additionally, tRNA tpm improves the predictive power of tRNA adaptation index over codon preference. Our results suggest that dependence of codon usage on tRNA availability is not always associated with species growth-rate. Conversely, tRNA availability is better optimized to codon usage in fast-growing than slow-growing species.
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31
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Mohammad F, Green R, Buskirk AR. A systematically-revised ribosome profiling method for bacteria reveals pauses at single-codon resolution. eLife 2019; 8:e42591. [PMID: 30724162 PMCID: PMC6377232 DOI: 10.7554/elife.42591] [Citation(s) in RCA: 110] [Impact Index Per Article: 22.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2018] [Accepted: 02/05/2019] [Indexed: 12/17/2022] Open
Abstract
In eukaryotes, ribosome profiling provides insight into the mechanism of protein synthesis at the codon level. In bacteria, however, the method has been more problematic and no consensus has emerged for how to best prepare profiling samples. Here, we identify the sources of these problems and describe new solutions for arresting translation and harvesting cells in order to overcome them. These improvements remove confounding artifacts and improve the resolution to allow analyses of ribosome behavior at the codon level. With a clearer view of the translational landscape in vivo, we observe that filtering cultures leads to translational pauses at serine and glycine codons through the reduction of tRNA aminoacylation levels. This observation illustrates how bacterial ribosome profiling studies can yield insight into the mechanism of protein synthesis at the codon level and how these mechanisms are regulated in response to changes in the physiology of the cell.
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Affiliation(s)
- Fuad Mohammad
- Department of Molecular Biology and GeneticsJohns Hopkins University School of MedicineBaltimoreUnited States
| | - Rachel Green
- Department of Molecular Biology and GeneticsJohns Hopkins University School of MedicineBaltimoreUnited States
- Howard Hughes Medical Institute, Johns Hopkins University School of MedicineBaltimoreUnited States
| | - Allen R Buskirk
- Department of Molecular Biology and GeneticsJohns Hopkins University School of MedicineBaltimoreUnited States
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32
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Zhang J, Chetnani B, Cormack ED, Alonso D, Liu W, Mondragón A, Fei J. Specific structural elements of the T-box riboswitch drive the two-step binding of the tRNA ligand. eLife 2018; 7:39518. [PMID: 30251626 PMCID: PMC6197855 DOI: 10.7554/elife.39518] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2018] [Accepted: 09/24/2018] [Indexed: 12/29/2022] Open
Abstract
T-box riboswitches are cis-regulatory RNA elements that regulate the expression of proteins involved in amino acid biosynthesis and transport by binding to specific tRNAs and sensing their aminoacylation state. While the T-box modular structural elements that recognize different parts of a tRNA have been identified, the kinetic trajectory describing how these interactions are established temporally remains unclear. Using smFRET, we demonstrate that tRNA binds to the riboswitch in two steps, first anticodon recognition followed by the sensing of the 3’ NCCA end, with the second step accompanied by a T-box riboswitch conformational change. Studies on site-specific mutants highlight that specific T-box structural elements drive the two-step binding process in a modular fashion. Our results set up a kinetic framework describing tRNA binding by T-box riboswitches, and suggest such binding mechanism is kinetically beneficial for efficient, co-transcriptional recognition of the cognate tRNA ligand. Living organisms depend upon a group of chemicals called amino acids to survive. Amino acids are the building blocks of proteins, and proteins have many important roles within and around cells. Bacteria regulate certain genes to ensure they have the right balance of different amino acids to survive. By controlling the availability of certain proteins that help them to make or collect certain amino acids, bacteria can control their overall amino acid balance. Before a protein is made, a molecular machine called RNA polymerase must first copy the information in a gene to make a molecule called a messenger RNA (mRNA). The mRNA is then translated to make the protein from individual amino acids. In this process, each amino acid needs to be first attached to another molecule called a transfer RNA (tRNA). In many bacteria species, the mRNAs involved in making or transporting amino acids contain structures called T-boxes. These structures guide the RNA polymerase to make more of the mRNAs when the levels of the amino acid become too low. A T-box, however, does not sense the level of the amino acid directly. Instead it senses the number of tRNA molecules that do not carry an amino acid. Zhang, Chetnani et al. examined a particular T-box interacting with tRNA using pairs of fluorescent dyes to detect distances between molecules. The T-box first recognizes a part of the tRNA called the anticodon to make sure it binds the correct type of tRNA. It then changes its shape to detect whether the tRNA is attached to an amino acid. This two-step process is driven by multiple structural elements within the T-box, and the flexibility of the T-box plays a critical role. A cell’s survival depends on it keeping amino acid levels under control. Understanding how bacteria do this could lead to new antibiotic drugs that target the T-box to kill cells. This study also provides insights into the workings of mRNA components like T-boxes – a type of riboswitch – which is an unusual means of controlling gene activity.
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Affiliation(s)
- Jiacheng Zhang
- Institute for Biophysical Dynamics, University of Chicago, Chicago, United States
| | - Bhaskar Chetnani
- Department of Molecular Biosciences, Northwestern University, Evanston, United States
| | | | - Dulce Alonso
- Department of Molecular Biosciences, Northwestern University, Evanston, United States
| | - Wei Liu
- Department of Biochemistry and Molecular Biology, University of Chicago, Chicago, United States
| | - Alfonso Mondragón
- Department of Molecular Biosciences, Northwestern University, Evanston, United States
| | - Jingyi Fei
- Institute for Biophysical Dynamics, University of Chicago, Chicago, United States.,Department of Biochemistry and Molecular Biology, University of Chicago, Chicago, United States
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33
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Zheng B, Ma X, Wang N, Ding T, Guo L, Zhang X, Yang Y, Li C, Huo YX. Utilization of rare codon-rich markers for screening amino acid overproducers. Nat Commun 2018; 9:3616. [PMID: 30190534 PMCID: PMC6127279 DOI: 10.1038/s41467-018-05830-0] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2017] [Accepted: 07/27/2018] [Indexed: 11/24/2022] Open
Abstract
The translation of rare codons relies on their corresponding rare tRNAs, which could not be fully charged under amino acid starvation. Theoretically, disrupted or retarded translation caused by the lack of charged rare tRNAs can be partially restored by feeding or intracellular synthesis of the corresponding amino acids. Inspired by this assumption, we develop a screening or selection system for obtaining overproducers of a target amino acid by replacing its common codons with the corresponding synonymous rare alternative in the coding sequence of selected reporter proteins or antibiotic-resistant markers. Results show that integration of rare codons can inhibit gene translations in a frequency-dependent manner. As a proof-of-concept, Escherichia coli strains overproducing L-leucine, L-arginine or L-serine are successfully selected from random mutation libraries. The system is also applied to Corynebacterium glutamicum to screen out L-arginine overproducers. This strategy sheds new light on obtaining and understanding amino acid overproduction strains.
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Affiliation(s)
- Bo Zheng
- School of Life Science, Beijing Institute of Technology, No. 5 South Zhongguancun Street, 100081, Beijing, China
| | - Xiaoyan Ma
- School of Life Science, Beijing Institute of Technology, No. 5 South Zhongguancun Street, 100081, Beijing, China
| | - Ning Wang
- School of Life Science, Beijing Institute of Technology, No. 5 South Zhongguancun Street, 100081, Beijing, China
| | - Tingting Ding
- School of Life Science, Beijing Institute of Technology, No. 5 South Zhongguancun Street, 100081, Beijing, China
| | - Liwei Guo
- School of Life Science, Beijing Institute of Technology, No. 5 South Zhongguancun Street, 100081, Beijing, China
- UCLA Institute of Advancement (Suzhou), 10 Yueliangwan Road, Suzhou Industrial Park, 215123, Suzhou, China
| | - Xiaorong Zhang
- Institute of Biophysics, Chinese Academy of Sciences, 15 Datun Road, Chaoyang District, 100101, Beijing, China
| | - Yu Yang
- School of Life Science, Beijing Institute of Technology, No. 5 South Zhongguancun Street, 100081, Beijing, China
| | - Chun Li
- School of Chemistry and Chemical Engineering, Beijing Institute of Technology, No. 5 South Zhongguancun Street, 100081, Beijing, China
| | - Yi-Xin Huo
- School of Life Science, Beijing Institute of Technology, No. 5 South Zhongguancun Street, 100081, Beijing, China.
- UCLA Institute of Advancement (Suzhou), 10 Yueliangwan Road, Suzhou Industrial Park, 215123, Suzhou, China.
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Schörghuber J, Geist L, Platzer G, Feichtinger M, Bisaccia M, Scheibelberger L, Weber F, Konrat R, Lichtenecker RJ. Late metabolic precursors for selective aromatic residue labeling. JOURNAL OF BIOMOLECULAR NMR 2018; 71:129-140. [PMID: 29808436 PMCID: PMC6096522 DOI: 10.1007/s10858-018-0188-z] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 02/28/2018] [Accepted: 05/19/2018] [Indexed: 06/08/2023]
Abstract
In recent years, we developed a toolbox of heavy isotope containing compounds, which serve as metabolic amino acid precursors in the E. coli-based overexpression of aromatic residue labeled proteins. Our labeling techniques show excellent results both in terms of selectivity and isotope incorporation levels. They are additionally distinguished by low sample production costs and meet the economic demands to further implement protein NMR spectroscopy as a routinely used method in drug development processes. Different isotopologues allow for the assembly of optimized protein samples, which fulfill the requirements of various NMR experiments to elucidate protein structures, analyze conformational dynamics, or probe interaction surfaces. In the present article, we want to summarize the precursors we developed so far and give examples of their special value in the probing of protein-ligand interaction.
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Affiliation(s)
- Julia Schörghuber
- Institute of Organic Chemistry, University of Vienna, Währinger Str. 38, 1090, Vienna, Austria
| | - Leonhard Geist
- Christian Doppler Laboratory for High-Content Structural Biology and Biotechnology, Department of Structural and Computational Biology, Max F. Perutz Laboratories, University of Vienna, Dr-Bohr-Gasse 9, 1030, Vienna, Austria
| | - Gerald Platzer
- Christian Doppler Laboratory for High-Content Structural Biology and Biotechnology, Department of Structural and Computational Biology, Max F. Perutz Laboratories, University of Vienna, Dr-Bohr-Gasse 9, 1030, Vienna, Austria
| | - Michael Feichtinger
- Christian Doppler Laboratory for High-Content Structural Biology and Biotechnology, Department of Structural and Computational Biology, Max F. Perutz Laboratories, University of Vienna, Dr-Bohr-Gasse 9, 1030, Vienna, Austria
| | - Marilena Bisaccia
- Institute of Organic Chemistry, University of Vienna, Währinger Str. 38, 1090, Vienna, Austria
| | - Lukas Scheibelberger
- Institute of Organic Chemistry, University of Vienna, Währinger Str. 38, 1090, Vienna, Austria
| | - Frederik Weber
- Institute of Organic Chemistry, University of Vienna, Währinger Str. 38, 1090, Vienna, Austria
| | - Robert Konrat
- Christian Doppler Laboratory for High-Content Structural Biology and Biotechnology, Department of Structural and Computational Biology, Max F. Perutz Laboratories, University of Vienna, Dr-Bohr-Gasse 9, 1030, Vienna, Austria
| | - Roman J Lichtenecker
- Institute of Organic Chemistry, University of Vienna, Währinger Str. 38, 1090, Vienna, Austria.
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Rojas J, Castillo G, Leiva LE, Elgamal S, Orellana O, Ibba M, Katz A. Codon usage revisited: Lack of correlation between codon usage and the number of tRNA genes in enterobacteria. Biochem Biophys Res Commun 2018; 502:450-455. [PMID: 29859934 DOI: 10.1016/j.bbrc.2018.05.168] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2018] [Accepted: 05/25/2018] [Indexed: 01/01/2023]
Abstract
It is widely believed that if a high number of genes are found for any tRNA in a rapidly replicating bacteria, then the cytoplasmic levels of that tRNA will be high and an open reading frame containing a higher frequency of the complementary codon will be translated faster. This idea is based on correlations between the number of tRNA genes, tRNA concentration and the frequency of codon usage observed in a limited number of strains as well as from the fact that artificially changing the number of tRNA genes alters translation efficiency and consequently the amount of properly folded protein synthesized. tRNA gene number may greatly vary in a genome due to duplications, deletions and lateral transfer which in turn would alter the levels and functionality of many proteins. Such changes are potentially deleterious for fitness and as a result it is expected that changes in tRNA gene numbers should be accompanied by a modification of the frequency of codon usage. In contrast to this model, when comparing the number of tRNA genes and the frequency of codon usage of several Salmonella enterica and Escherichia coli strains we found that changes in the number of tRNA genes are not correlated to changes in codon usage. Furthermore, these changes are not correlated with a change in the efficiency of codon translation. These results suggest that once a genome gains or loses tRNA genes, it responds by modulating the concentrations of tRNAs rather than modifying its frequency of codon usage.
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Affiliation(s)
- Joaquín Rojas
- Programa de Biología Celular y Molecular, ICBM, Facultad de Medicina, Universidad de Chile, Santiago, 8380453, Chile
| | - Gabriel Castillo
- Programa de Biología Celular y Molecular, ICBM, Facultad de Medicina, Universidad de Chile, Santiago, 8380453, Chile
| | - Lorenzo Eugenio Leiva
- Programa de Biología Celular y Molecular, ICBM, Facultad de Medicina, Universidad de Chile, Santiago, 8380453, Chile
| | - Sara Elgamal
- Department of Microbiology and The Center for RNA Biology, Ohio State University, Columbus, OH, 43210, USA
| | - Omar Orellana
- Programa de Biología Celular y Molecular, ICBM, Facultad de Medicina, Universidad de Chile, Santiago, 8380453, Chile
| | - Michael Ibba
- Department of Microbiology and The Center for RNA Biology, Ohio State University, Columbus, OH, 43210, USA
| | - Assaf Katz
- Programa de Biología Celular y Molecular, ICBM, Facultad de Medicina, Universidad de Chile, Santiago, 8380453, Chile.
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36
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tRNA tracking for direct measurements of protein synthesis kinetics in live cells. Nat Chem Biol 2018; 14:618-626. [PMID: 29769736 PMCID: PMC6124642 DOI: 10.1038/s41589-018-0063-y] [Citation(s) in RCA: 31] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2017] [Accepted: 04/09/2018] [Indexed: 11/30/2022]
Abstract
Our ability to directly relate results from test tube biochemical experiments to the kinetics in living cells is very limited. Here we present experimental and analytical tools to directly study the kinetics of fast biochemical reactions in live cells. Dye-labeled molecules are electroporated into bacterial cells and tracked using super-resolved single-molecule microscopy. Trajectories are analyzed by machine-learning algorithms to directly monitor transitions between bound and free states. In particular, we measure the dwell-time of tRNAs on ribosomes, and hence achieve direct measurements of translation rates inside living cells at codon resolution. We find elongation rates with tRNAPhe in perfect agreement with previous indirect estimates, and that once fMet-tRNAfMet has bound to the 30S ribosomal subunit, initiation of translation is surprisingly fast and does not limit the overall rate of protein synthesis. The experimental and analytical tools for direct kinetics measurements in live cells have applications far beyond bacterial protein synthesis.
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37
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Morgan GJ, Burkhardt DH, Kelly JW, Powers ET. Translation efficiency is maintained at elevated temperature in Escherichia coli. J Biol Chem 2017; 293:777-793. [PMID: 29183994 DOI: 10.1074/jbc.ra117.000284] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2017] [Revised: 11/22/2017] [Indexed: 01/30/2023] Open
Abstract
Cellular protein levels are dictated by the balance between gene transcription, mRNA translation, and protein degradation, among other factors. Translation requires the interplay of several RNA hybridization processes, which are expected to be temperature-sensitive. We used ribosome profiling to monitor translation in Escherichia coli at 30 °C and to investigate how this changes after 10-20 min of heat shock at 42 °C. Translation efficiencies are robustly maintained after thermal heat shock and after mimicking the heat-shock response transcriptional program at 30 °C by overexpressing the heat shock σ factor encoded by the rpoH gene. We compared translation efficiency, the ratio of ribosome footprint reads to mRNA reads for each gene, to parameters derived from gene sequences. Genes with stable mRNA structures, non-optimal codon use, and those whose gene product is cotranslationally translocated into the inner membrane are generally less highly translated than other genes. Comparison with other published datasets suggests a role for translational elongation in coupling mRNA structures to translation initiation. Genome-wide calculations of the temperature dependence of mRNA structure predict that relatively few mRNAs show a melting transition between 30 and 42 °C, consistent with the observed lack of changes in translation efficiency. We developed a linear model with six parameters that can predict 38% of the variation in translation efficiency between genes, which may be useful in interpreting transcriptome data.
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Affiliation(s)
- Gareth J Morgan
- From the Departments of Chemistry and Molecular Medicine and
| | - David H Burkhardt
- California Institute of Quantitative Biosciences and Department of Microbiology and Immunology, University of California, San Francisco, San Francisco, California 94158
| | - Jeffery W Kelly
- From the Departments of Chemistry and Molecular Medicine and.,Skaggs Institute for Chemical Biology, The Scripps Research Institute, La, Jolla, California 92037, and
| | - Evan T Powers
- From the Departments of Chemistry and Molecular Medicine and
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38
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Growth-Rate Dependent Regulation of tRNA Level and Charging in Bacillus licheniformis. J Mol Biol 2017; 429:3102-3112. [DOI: 10.1016/j.jmb.2017.09.010] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2017] [Revised: 09/09/2017] [Accepted: 09/09/2017] [Indexed: 11/21/2022]
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Evans ME, Clark WC, Zheng G, Pan T. Determination of tRNA aminoacylation levels by high-throughput sequencing. Nucleic Acids Res 2017; 45:e133. [PMID: 28586482 PMCID: PMC5737633 DOI: 10.1093/nar/gkx514] [Citation(s) in RCA: 63] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2017] [Revised: 05/15/2017] [Accepted: 05/31/2017] [Indexed: 01/03/2023] Open
Abstract
Transfer RNA (tRNA) decodes mRNA codons when aminoacylated (charged) with an amino acid at its 3' end. Charged tRNAs turn over rapidly in cells, and variations in charged tRNA fractions are known to be a useful parameter in cellular responses to stress. tRNA charging fractions can be measured for individual tRNA species using acid denaturing gels, or comparatively at the genome level using microarrays. These hybridization-based approaches cannot be used for high resolution analysis of mammalian tRNAs due to their large sequence diversity. Here we develop a high-throughput sequencing method that enables accurate determination of charged tRNA fractions at single-base resolution (Charged DM-tRNA-seq). Our method takes advantage of the recently developed DM-tRNA-seq method, but includes additional chemical steps that specifically remove the 3'A residue in uncharged tRNA. Charging fraction is obtained by counting the fraction of A-ending reads versus A+C-ending reads for each tRNA species in the same sequencing reaction. In HEK293T cells, most cytosolic tRNAs are charged at >80% levels, whereas tRNASer and tRNAThr are charged at lower levels. These low charging levels were validated using acid denaturing gels. Our method should be widely applicable for investigations of tRNA charging as a parameter in biological regulation.
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Affiliation(s)
- Molly E. Evans
- Department of Biochemistry & Molecular Biology, University of Chicago, Chicago, IL 60637, USA
| | - Wesley C. Clark
- Department of Biochemistry & Molecular Biology, University of Chicago, Chicago, IL 60637, USA
| | - Guanqun Zheng
- Department of Biochemistry & Molecular Biology, University of Chicago, Chicago, IL 60637, USA
| | - Tao Pan
- Department of Biochemistry & Molecular Biology, University of Chicago, Chicago, IL 60637, USA
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40
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Ferro I, Chelysheva I, Ignatova Z. Competition for amino acid flux among translation, growth and detoxification in bacteria. RNA Biol 2017; 15:991-994. [PMID: 28296576 DOI: 10.1080/15476286.2017.1306174] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022] Open
Abstract
Transfer-tRNAs (tRNAs) are central entities for translation that deliver amino acids to the ribosome to translate genetic information in an mRNA-template dependent manner. Recent discoveries from our laboratory show that in E. coli and B. licheniformis, some tRNAs are poorly charged despite the plentiful intracellular cognate amino acid. Specifically, tRNAs carrying amino acids that exert toxicity and inhibit bacterial growth when added separately to the growth medium are poorly charged. Here, we discuss various evolutionary strategies different bacterial cells have adopted to precisely hone the competition between amino acid utilization for translation and proliferation and combat the inhibitory effect toward maximizing bacterial fitness. These data add a new twist to the amino acid flux models and to our understanding of the complex intimate link between dynamics of translation and bacterial growth.
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Affiliation(s)
- Iolanda Ferro
- a Institute of Biochemistry and Molecular Biology, University of Hamburg , Germany
| | - Irina Chelysheva
- a Institute of Biochemistry and Molecular Biology, University of Hamburg , Germany
| | - Zoya Ignatova
- a Institute of Biochemistry and Molecular Biology, University of Hamburg , Germany
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