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The Mechanism of Bacterial Resistance and Potential Bacteriostatic Strategies. Antibiotics (Basel) 2022; 11:antibiotics11091215. [PMID: 36139994 PMCID: PMC9495013 DOI: 10.3390/antibiotics11091215] [Citation(s) in RCA: 20] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2022] [Revised: 09/04/2022] [Accepted: 09/05/2022] [Indexed: 12/26/2022] Open
Abstract
Bacterial drug resistance is rapidly developing as one of the greatest threats to human health. Bacteria will adopt corresponding strategies to crack the inhibitory effect of antibiotics according to the antibacterial mechanism of antibiotics, involving the mutation of drug target, secreting hydrolase, and discharging antibiotics out of cells through an efflux pump, etc. In recent years, bacteria are found to constantly evolve new resistance mechanisms to antibiotics, including target protective protein, changes in cell morphology, and so on, endowing them with multiple defense systems against antibiotics, leading to the emergence of multi-drug resistant (MDR) bacteria and the unavailability of drugs in clinics. Correspondingly, researchers attempt to uncover the mystery of bacterial resistance to develop more convenient and effective antibacterial strategies. Although traditional antibiotics still play a significant role in the treatment of diseases caused by sensitive pathogenic bacteria, they gradually lose efficacy in the MDR bacteria. Therefore, highly effective antibacterial compounds, such as phage therapy and CRISPER-Cas precision therapy, are gaining an increasing amount of attention, and are considered to be the treatments with the moist potential with regard to resistance against MDR in the future. In this review, nine identified drug resistance mechanisms are summarized, which enhance the retention rate of bacteria under the action of antibiotics and promote the distribution of drug-resistant bacteria (DRB) in the population. Afterwards, three kinds of potential antibacterial methods are introduced, in which new antibacterial compounds exhibit broad application prospects with different action mechanisms, the phage therapy has been successfully applied to infectious diseases caused by super bacteria, and the CRISPER-Cas precision therapy as a new technology can edit drug-resistant genes in pathogenic bacteria at the gene level, with high accuracy and flexibility. These antibacterial methods will provide more options for clinical treatment, and will greatly alleviate the current drug-resistant crisis.
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Tu B, Cao N, Zhang B, Zheng W, Li J, Tang X, Su K, Li J, Zhang Z, Yan Z, Li D, Zheng X, Zhang K, Hong WD, Wu P. Synthesis and Biological Evaluation of Novel Fusidic Acid Derivatives as Two-in-One Agent with Potent Antibacterial and Anti-Inflammatory Activity. Antibiotics (Basel) 2022; 11:antibiotics11081026. [PMID: 36009895 PMCID: PMC9405029 DOI: 10.3390/antibiotics11081026] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2022] [Revised: 07/24/2022] [Accepted: 07/28/2022] [Indexed: 12/10/2022] Open
Abstract
Fusidic acid (FA), a narrow-spectrum antibiotics, is highly sensitive to various Gram-positive cocci associated with skin infections. It has outstanding antibacterial effects against certain Gram-positive bacteria whilst no cross-resistance with other antibiotics. Two series of FA derivatives were synthesized and their antibacterial activities were tested. A new aromatic side-chain analog, FA-15 exhibited good antibacterial activity with MIC values in the range of 0.781–1.563 µM against three strains of Staphylococcus spp. Furthermore, through the assessment by the kinetic assay, similar characteristics of bacteriostasis by FA and its aromatic derivatives were observed. In addition, anti-inflammatory activities of FA and its aromatic derivatives were evaluated by using a 12-O-tetradecanoylphorbol-13-acetate (TPA) induced mouse ear edema model. The results also indicated that FA and its aromatic derivatives effectively reduced TPA-induced ear edema in a dose-dependent manner. Following, multiform computerized simulation, including homology modeling, molecular docking, molecular dynamic simulation and QSAR was conducted to clarify the mechanism and regularity of activities. Overall, the present work gave vital clues about structural modifications and has profound significance in deeply scouting for bioactive potentials of FA and its derivatives.
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Affiliation(s)
- Borong Tu
- School of Biotechnology and Health Sciences, Wuyi University, Jiangmen 529020, China; (B.T.); (N.C.); (W.Z.); (J.L.); (X.T.); (K.S.); (J.L.); (Z.Z.); (Z.Y.); (D.L.); (X.Z.)
- International Healthcare Innovation Institute (Jiangmen), Jiangmen 529040, China
| | - Nana Cao
- School of Biotechnology and Health Sciences, Wuyi University, Jiangmen 529020, China; (B.T.); (N.C.); (W.Z.); (J.L.); (X.T.); (K.S.); (J.L.); (Z.Z.); (Z.Y.); (D.L.); (X.Z.)
- International Healthcare Innovation Institute (Jiangmen), Jiangmen 529040, China
| | - Bingjie Zhang
- School of Biomedicine and Pharmaceutical Sciences, Guangdong University of Technology, Guangzhou 510006, China;
| | - Wende Zheng
- School of Biotechnology and Health Sciences, Wuyi University, Jiangmen 529020, China; (B.T.); (N.C.); (W.Z.); (J.L.); (X.T.); (K.S.); (J.L.); (Z.Z.); (Z.Y.); (D.L.); (X.Z.)
- International Healthcare Innovation Institute (Jiangmen), Jiangmen 529040, China
| | - Jiahao Li
- School of Biotechnology and Health Sciences, Wuyi University, Jiangmen 529020, China; (B.T.); (N.C.); (W.Z.); (J.L.); (X.T.); (K.S.); (J.L.); (Z.Z.); (Z.Y.); (D.L.); (X.Z.)
- International Healthcare Innovation Institute (Jiangmen), Jiangmen 529040, China
| | - Xiaowen Tang
- School of Biotechnology and Health Sciences, Wuyi University, Jiangmen 529020, China; (B.T.); (N.C.); (W.Z.); (J.L.); (X.T.); (K.S.); (J.L.); (Z.Z.); (Z.Y.); (D.L.); (X.Z.)
- International Healthcare Innovation Institute (Jiangmen), Jiangmen 529040, China
| | - Kaize Su
- School of Biotechnology and Health Sciences, Wuyi University, Jiangmen 529020, China; (B.T.); (N.C.); (W.Z.); (J.L.); (X.T.); (K.S.); (J.L.); (Z.Z.); (Z.Y.); (D.L.); (X.Z.)
- International Healthcare Innovation Institute (Jiangmen), Jiangmen 529040, China
| | - Jinxuan Li
- School of Biotechnology and Health Sciences, Wuyi University, Jiangmen 529020, China; (B.T.); (N.C.); (W.Z.); (J.L.); (X.T.); (K.S.); (J.L.); (Z.Z.); (Z.Y.); (D.L.); (X.Z.)
- International Healthcare Innovation Institute (Jiangmen), Jiangmen 529040, China
| | - Zhen Zhang
- School of Biotechnology and Health Sciences, Wuyi University, Jiangmen 529020, China; (B.T.); (N.C.); (W.Z.); (J.L.); (X.T.); (K.S.); (J.L.); (Z.Z.); (Z.Y.); (D.L.); (X.Z.)
- International Healthcare Innovation Institute (Jiangmen), Jiangmen 529040, China
| | - Zhenping Yan
- School of Biotechnology and Health Sciences, Wuyi University, Jiangmen 529020, China; (B.T.); (N.C.); (W.Z.); (J.L.); (X.T.); (K.S.); (J.L.); (Z.Z.); (Z.Y.); (D.L.); (X.Z.)
- International Healthcare Innovation Institute (Jiangmen), Jiangmen 529040, China
| | - Dongli Li
- School of Biotechnology and Health Sciences, Wuyi University, Jiangmen 529020, China; (B.T.); (N.C.); (W.Z.); (J.L.); (X.T.); (K.S.); (J.L.); (Z.Z.); (Z.Y.); (D.L.); (X.Z.)
- International Healthcare Innovation Institute (Jiangmen), Jiangmen 529040, China
| | - Xi Zheng
- School of Biotechnology and Health Sciences, Wuyi University, Jiangmen 529020, China; (B.T.); (N.C.); (W.Z.); (J.L.); (X.T.); (K.S.); (J.L.); (Z.Z.); (Z.Y.); (D.L.); (X.Z.)
- International Healthcare Innovation Institute (Jiangmen), Jiangmen 529040, China
| | - Kun Zhang
- School of Biotechnology and Health Sciences, Wuyi University, Jiangmen 529020, China; (B.T.); (N.C.); (W.Z.); (J.L.); (X.T.); (K.S.); (J.L.); (Z.Z.); (Z.Y.); (D.L.); (X.Z.)
- International Healthcare Innovation Institute (Jiangmen), Jiangmen 529040, China
- School of Biomedicine and Pharmaceutical Sciences, Guangdong University of Technology, Guangzhou 510006, China;
- Correspondence: (K.Z.); (W.D.H.); (P.W.); Tel.: +86-13822330019 (K.Z.); +44-7863354263 (W.D.H.); +86-18825179347 (P.W.)
| | - Weiqian David Hong
- School of Biotechnology and Health Sciences, Wuyi University, Jiangmen 529020, China; (B.T.); (N.C.); (W.Z.); (J.L.); (X.T.); (K.S.); (J.L.); (Z.Z.); (Z.Y.); (D.L.); (X.Z.)
- International Healthcare Innovation Institute (Jiangmen), Jiangmen 529040, China
- Department of Chemistry, University of Liverpool, Liverpool L69 7ZD, UK
- Correspondence: (K.Z.); (W.D.H.); (P.W.); Tel.: +86-13822330019 (K.Z.); +44-7863354263 (W.D.H.); +86-18825179347 (P.W.)
| | - Panpan Wu
- School of Biotechnology and Health Sciences, Wuyi University, Jiangmen 529020, China; (B.T.); (N.C.); (W.Z.); (J.L.); (X.T.); (K.S.); (J.L.); (Z.Z.); (Z.Y.); (D.L.); (X.Z.)
- International Healthcare Innovation Institute (Jiangmen), Jiangmen 529040, China
- School of Biomedicine and Pharmaceutical Sciences, Guangdong University of Technology, Guangzhou 510006, China;
- Correspondence: (K.Z.); (W.D.H.); (P.W.); Tel.: +86-13822330019 (K.Z.); +44-7863354263 (W.D.H.); +86-18825179347 (P.W.)
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3
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Wang A, Levi M, Mohanty U, Whitford PC. Diffuse Ions Coordinate Dynamics in a Ribonucleoprotein Assembly. J Am Chem Soc 2022; 144:9510-9522. [PMID: 35593477 DOI: 10.1021/jacs.2c04082] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Proper ionic concentrations are required for the functional dynamics of RNA and ribonucleoprotein (RNP) assemblies. While experimental and computational techniques have provided many insights into the properties of chelated ions, less is known about the energetic contributions of diffuse ions to large-scale conformational rearrangements. To address this, we present a model that is designed to quantify the influence of diffuse monovalent and divalent ions on the dynamics of biomolecular assemblies. This model employs all-atom (non-H) resolution and explicit ions, where effective potentials account for hydration effects. We first show that the model accurately predicts the number of excess Mg2+ ions for prototypical RNA systems, at a level comparable to modern coarse-grained models. We then apply the model to a complete ribosome and show how the balance between diffuse Mg2+ and K+ ions can control the dynamics of tRNA molecules during translation. The model predicts differential effects of diffuse ions on the free-energy barrier associated with tRNA entry and the energy of tRNA binding to the ribosome. Together, this analysis reveals the direct impact of diffuse ions on the dynamics of an RNP assembly.
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Affiliation(s)
- Ailun Wang
- Department of Chemistry, Boston College, Chestnut Hill, Massachusetts 02467, United States.,Center for Theoretical Biological Physics, Northeastern University, 360 Huntington Avenue, Boston, Massachusetts 02115, United States
| | - Mariana Levi
- Department of Physics, Northeastern University, Dana Research Center 111, 360 Huntington Avenue, Boston, Massachusetts 02115, United States
| | - Udayan Mohanty
- Department of Chemistry, Boston College, Chestnut Hill, Massachusetts 02467, United States
| | - Paul C Whitford
- Center for Theoretical Biological Physics, Northeastern University, 360 Huntington Avenue, Boston, Massachusetts 02115, United States.,Department of Physics, Northeastern University, Dana Research Center 111, 360 Huntington Avenue, Boston, Massachusetts 02115, United States
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4
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Zhu M, Mu H, Han F, Wang Q, Dai X. Quantitative analysis of asynchronous transcription-translation and transcription processivity in Bacillus subtilis under various growth conditions. iScience 2021; 24:103333. [PMID: 34805793 PMCID: PMC8586808 DOI: 10.1016/j.isci.2021.103333] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2020] [Revised: 08/31/2021] [Accepted: 10/20/2021] [Indexed: 10/25/2022] Open
Abstract
Tight coordination between transcription and translation has long been recognized as the hallmark of gene expression in bacteria. In Escherichia coli cells, disruption of the transcription-translation coordination leads to the loss of transcription processivity via triggering Rho-mediated premature transcription termination. Here we quantitatively characterize the transcription and translation kinetics in Gram-positive model bacterium Bacillus subtilis. We found that the speed of transcription elongation is much faster than that of translation elongation in B. subtilis under various growth conditions. Moreover, a Rho-independent loss of transcription processivity occurs constitutively in several genes/operons but is not subject to translational control. When the transcription elongation is decelerated under poor nutrients, low temperature, or nucleotide depletion, the loss of transcription processivity is strongly enhanced, suggesting that its degree is modulated by the speed of transcription elongation. Our study reveals distinct design principles of gene expression in E. coli and B. subtilis.
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Affiliation(s)
- Manlu Zhu
- Hubei Key Laboratory of Genetic Regulation and Integrative Biology, School of Life Sciences, Central China Normal University, Wuhan, Hubei Province, China
| | - Haoyan Mu
- Hubei Key Laboratory of Genetic Regulation and Integrative Biology, School of Life Sciences, Central China Normal University, Wuhan, Hubei Province, China
| | - Fei Han
- Hubei Key Laboratory of Genetic Regulation and Integrative Biology, School of Life Sciences, Central China Normal University, Wuhan, Hubei Province, China
| | - Qian Wang
- Hubei Key Laboratory of Genetic Regulation and Integrative Biology, School of Life Sciences, Central China Normal University, Wuhan, Hubei Province, China
| | - Xiongfeng Dai
- Hubei Key Laboratory of Genetic Regulation and Integrative Biology, School of Life Sciences, Central China Normal University, Wuhan, Hubei Province, China
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5
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Ero R, Yan XF, Gao YG. Ribosome Protection Proteins-"New" Players in the Global Arms Race with Antibiotic-Resistant Pathogens. Int J Mol Sci 2021; 22:5356. [PMID: 34069640 PMCID: PMC8161019 DOI: 10.3390/ijms22105356] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2021] [Revised: 05/12/2021] [Accepted: 05/14/2021] [Indexed: 01/07/2023] Open
Abstract
Bacteria have evolved an array of mechanisms enabling them to resist the inhibitory effect of antibiotics, a significant proportion of which target the ribosome. Indeed, resistance mechanisms have been identified for nearly every antibiotic that is currently used in clinical practice. With the ever-increasing list of multi-drug-resistant pathogens and very few novel antibiotics in the pharmaceutical pipeline, treatable infections are likely to become life-threatening once again. Most of the prevalent resistance mechanisms are well understood and their clinical significance is recognized. In contrast, ribosome protection protein-mediated resistance has flown under the radar for a long time and has been considered a minor factor in the clinical setting. Not until the recent discovery of the ATP-binding cassette family F protein-mediated resistance in an extensive list of human pathogens has the significance of ribosome protection proteins been truly appreciated. Understanding the underlying resistance mechanism has the potential to guide the development of novel therapeutic approaches to evade or overcome the resistance. In this review, we discuss the latest developments regarding ribosome protection proteins focusing on the current antimicrobial arsenal and pharmaceutical pipeline as well as potential implications for the future of fighting bacterial infections in the time of "superbugs."
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Affiliation(s)
- Rya Ero
- Department of Molecular Biology, Institute of Molecular and Cell Biology, University of Tartu, 51010 Tartu, Estonia
- School of Biological Sciences, Nanyang Technological University, Singapore 637551, Singapore;
| | - Xin-Fu Yan
- School of Biological Sciences, Nanyang Technological University, Singapore 637551, Singapore;
| | - Yong-Gui Gao
- School of Biological Sciences, Nanyang Technological University, Singapore 637551, Singapore;
- NTU Institute of Structural Biology, Nanyang Technological University, Singapore 639798, Singapore
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6
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Lee M, Matsunaga N, Akabane S, Yasuda I, Ueda T, Takeuchi-Tomita N. Reconstitution of mammalian mitochondrial translation system capable of correct initiation and long polypeptide synthesis from leaderless mRNA. Nucleic Acids Res 2021; 49:371-382. [PMID: 33300043 PMCID: PMC7797035 DOI: 10.1093/nar/gkaa1165] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2020] [Revised: 11/12/2020] [Accepted: 11/16/2020] [Indexed: 12/31/2022] Open
Abstract
Mammalian mitochondria have their own dedicated protein synthesis system, which produces 13 essential subunits of the oxidative phosphorylation complexes. We have reconstituted an in vitro translation system from mammalian mitochondria, utilizing purified recombinant mitochondrial translation factors, 55S ribosomes from pig liver mitochondria, and a tRNA mixture from either Escherichia coli or yeast. The system is capable of translating leaderless mRNAs encoding model proteins (DHFR and nanoLuciferase) or some mtDNA-encoded proteins. We show that a leaderless mRNA, encoding nanoLuciferase, is faithfully initiated without the need for any auxiliary factors other than IF-2mt and IF-3mt. We found that the ribosome-dependent GTPase activities of both the translocase EF-G1mt and the recycling factor EF-G2mt are insensitive to fusidic acid (FA), the translation inhibitor that targets bacterial EF-G homologs, and consequently the system is resistant to FA. Moreover, we demonstrate that a polyproline sequence in the protein causes 55S mitochondrial ribosome stalling, yielding ribosome nascent chain complexes. Analyses of the effects of the Mg concentration on the polyproline-mediated ribosome stalling suggested the unique regulation of peptide elongation by the mitoribosome. This system will be useful for analyzing the mechanism of translation initiation, and the interactions between the nascent peptide chain and the mitochondrial ribosome.
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Affiliation(s)
- Muhoon Lee
- Department of Computational Biology and Medical Sciences, Graduate School of Frontier Sciences, The University of Tokyo, 5-1-5, Kashiwanoha, Kashiwa-shi, Chiba 277-8562, Japan
| | - Noriko Matsunaga
- Department of Computational Biology and Medical Sciences, Graduate School of Frontier Sciences, The University of Tokyo, 5-1-5, Kashiwanoha, Kashiwa-shi, Chiba 277-8562, Japan
| | - Shiori Akabane
- Department of Computational Biology and Medical Sciences, Graduate School of Frontier Sciences, The University of Tokyo, 5-1-5, Kashiwanoha, Kashiwa-shi, Chiba 277-8562, Japan.,Department of Life Science, Rikkyo University, Tokyo, 171-8501, Japan
| | - Ippei Yasuda
- Department of Computational Biology and Medical Sciences, Graduate School of Frontier Sciences, The University of Tokyo, 5-1-5, Kashiwanoha, Kashiwa-shi, Chiba 277-8562, Japan
| | - Takuya Ueda
- Department of Computational Biology and Medical Sciences, Graduate School of Frontier Sciences, The University of Tokyo, 5-1-5, Kashiwanoha, Kashiwa-shi, Chiba 277-8562, Japan.,Department of Integrative Bioscience and Biomedical Engineering, Graduate School of Science and Engineering, Waseda University, Tokyo, Shinjuku 162-8480, Japan
| | - Nono Takeuchi-Tomita
- Department of Computational Biology and Medical Sciences, Graduate School of Frontier Sciences, The University of Tokyo, 5-1-5, Kashiwanoha, Kashiwa-shi, Chiba 277-8562, Japan
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7
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Kummer E, Ban N. Structural insights into mammalian mitochondrial translation elongation catalyzed by mtEFG1. EMBO J 2020; 39:e104820. [PMID: 32602580 PMCID: PMC7396830 DOI: 10.15252/embj.2020104820] [Citation(s) in RCA: 30] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2020] [Revised: 05/08/2020] [Accepted: 05/11/2020] [Indexed: 01/08/2023] Open
Abstract
Mitochondria are eukaryotic organelles of bacterial origin where respiration takes place to produce cellular chemical energy. These reactions are catalyzed by the respiratory chain complexes located in the inner mitochondrial membrane. Notably, key components of the respiratory chain complexes are encoded on the mitochondrial chromosome and their expression relies on a dedicated mitochondrial translation machinery. Defects in the mitochondrial gene expression machinery lead to a variety of diseases in humans mostly affecting tissues with high energy demand such as the nervous system, the heart, or the muscles. The mitochondrial translation system has substantially diverged from its bacterial ancestor, including alterations in the mitoribosomal architecture, multiple changes to the set of translation factors and striking reductions in otherwise conserved tRNA elements. Although a number of structures of mitochondrial ribosomes from different species have been determined, our mechanistic understanding of the mitochondrial translation cycle remains largely unexplored. Here, we present two cryo-EM reconstructions of human mitochondrial elongation factor G1 bound to the mammalian mitochondrial ribosome at two different steps of the tRNA translocation reaction during translation elongation. Our structures explain the mechanism of tRNA and mRNA translocation on the mitoribosome, the regulation of mtEFG1 activity by the ribosomal GTPase-associated center, and the basis of decreased susceptibility of mtEFG1 to the commonly used antibiotic fusidic acid.
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Affiliation(s)
- Eva Kummer
- Department of BiologyInstitute of Molecular Biology and BiophysicsSwiss Federal Institute of Technology ZurichZurichSwitzerland
| | - Nenad Ban
- Department of BiologyInstitute of Molecular Biology and BiophysicsSwiss Federal Institute of Technology ZurichZurichSwitzerland
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8
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Abstract
Antibiotic resistance is mediated through several distinct mechanisms, most of which are relatively well understood and the clinical importance of which has long been recognized. Until very recently, neither of these statements was readily applicable to the class of resistance mechanism known as target protection, a phenomenon whereby a resistance protein physically associates with an antibiotic target to rescue it from antibiotic-mediated inhibition. In this Review, we summarize recent progress in understanding the nature and importance of target protection. In particular, we describe the molecular basis of the known target protection systems, emphasizing that target protection does not involve a single, uniform mechanism but is instead brought about in several mechanistically distinct ways.
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9
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Zhu M, Mori M, Hwa T, Dai X. Disruption of transcription-translation coordination in Escherichia coli leads to premature transcriptional termination. Nat Microbiol 2019; 4:2347-2356. [PMID: 31451774 PMCID: PMC6903697 DOI: 10.1038/s41564-019-0543-1] [Citation(s) in RCA: 53] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2019] [Accepted: 07/18/2019] [Indexed: 11/09/2022]
Abstract
Tight coordination between transcription and translation is crucial to maintaining the integrity of gene expression in bacteria, yet how bacteria manage to coordinate these two processes remains unclear. Possible direct physical coupling between the RNA polymerase and ribosome has been thoroughly investigated in recent years. Here, we quantitatively characterize the transcriptional kinetics of Escherichia coli under different growth conditions. Transcriptional and translational elongation remain coordinated under various nutrient conditions, as previously reported. However, transcriptional elongation was not affected under antibiotics that slowed down translational elongation. This result was also found by introducing nonsense mutation that completely dissociated transcription from translation. Our data thus provide direct evidence that translation is not required to maintain the speed of transcriptional elongation. In cases where transcription and translation are dissociated, our study provides quantitative characterization of the resulting process of premature transcriptional termination (PTT). PTT-mediated polarity caused by translation-targeting antibiotics substantially affected the coordinated expression of genes in several long operons, contributing to the key physiological effects of these antibiotics. Our results also suggest a model in which the coordination between transcriptional and translational elongation under normal growth conditions is implemented by guanosine tetraphosphate.
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Affiliation(s)
- Manlu Zhu
- School of Life Sciences, Central China Normal University, Wuhan, China
| | - Matteo Mori
- Department of Physics, University of California at San Diego, La Jolla, CA, USA
| | - Terence Hwa
- Department of Physics, University of California at San Diego, La Jolla, CA, USA.
| | - Xiongfeng Dai
- School of Life Sciences, Central China Normal University, Wuhan, China.
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10
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Polikanov YS, Aleksashin NA, Beckert B, Wilson DN. The Mechanisms of Action of Ribosome-Targeting Peptide Antibiotics. Front Mol Biosci 2018; 5:48. [PMID: 29868608 PMCID: PMC5960728 DOI: 10.3389/fmolb.2018.00048] [Citation(s) in RCA: 67] [Impact Index Per Article: 11.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2018] [Accepted: 04/23/2018] [Indexed: 12/31/2022] Open
Abstract
The ribosome is one of the major targets in the cell for clinically used antibiotics. However, the increase in multidrug resistant bacteria is rapidly reducing the effectiveness of our current arsenal of ribosome-targeting antibiotics, highlighting the need for the discovery of compounds with new scaffolds that bind to novel sites on the ribosome. One possible avenue for the development of new antimicrobial agents is by characterization and optimization of ribosome-targeting peptide antibiotics. Biochemical and structural data on ribosome-targeting peptide antibiotics illustrates the large diversity of scaffolds, binding interactions with the ribosome as well as mechanism of action to inhibit translation. The availability of high-resolution structures of ribosomes in complex with peptide antibiotics opens the way to structure-based design of these compounds as novel antimicrobial agents.
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Affiliation(s)
- Yury S Polikanov
- Department of Biological Sciences, University of Illinois at Chicago, Chicago, IL, United States.,Department of Medicinal Chemistry and Pharmacognosy, University of Illinois at Chicago, Chicago, IL, United States
| | - Nikolay A Aleksashin
- Center for Biomolecular Sciences, University of Illinois at Chicago, Chicago, IL, United States
| | - Bertrand Beckert
- Institute for Biochemistry and Molecular Biology, University of Hamburg, Hamburg, Germany
| | - Daniel N Wilson
- Institute for Biochemistry and Molecular Biology, University of Hamburg, Hamburg, Germany
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11
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Burkhart BJ, Schwalen CJ, Mann G, Naismith JH, Mitchell DA. YcaO-Dependent Posttranslational Amide Activation: Biosynthesis, Structure, and Function. Chem Rev 2017; 117:5389-5456. [PMID: 28256131 DOI: 10.1021/acs.chemrev.6b00623] [Citation(s) in RCA: 138] [Impact Index Per Article: 19.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
With advances in sequencing technology, uncharacterized proteins and domains of unknown function (DUFs) are rapidly accumulating in sequence databases and offer an opportunity to discover new protein chemistry and reaction mechanisms. The focus of this review, the formerly enigmatic YcaO superfamily (DUF181), has been found to catalyze a unique phosphorylation of a ribosomal peptide backbone amide upon attack by different nucleophiles. Established nucleophiles are the side chains of Cys, Ser, and Thr which gives rise to azoline/azole biosynthesis in ribosomally synthesized and posttranslationally modified peptide (RiPP) natural products. However, much remains unknown about the potential for YcaO proteins to collaborate with other nucleophiles. Recent work suggests potential in forming thioamides, macroamidines, and possibly additional post-translational modifications. This review covers all knowledge through mid-2016 regarding the biosynthetic gene clusters (BGCs), natural products, functions, mechanisms, and applications of YcaO proteins and outlines likely future research directions for this protein superfamily.
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Affiliation(s)
| | | | - Greg Mann
- Biomedical Science Research Complex, University of St Andrews , BSRC North Haugh, St Andrews KY16 9ST, United Kingdom
| | - James H Naismith
- Biomedical Science Research Complex, University of St Andrews , BSRC North Haugh, St Andrews KY16 9ST, United Kingdom.,State Key Laboratory of Biotherapy, Sichuan University , Sichuan, China
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12
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Reaction dynamics analysis of a reconstituted Escherichia coli protein translation system by computational modeling. Proc Natl Acad Sci U S A 2017; 114:E1336-E1344. [PMID: 28167777 DOI: 10.1073/pnas.1615351114] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
To elucidate the dynamic features of a biologically relevant large-scale reaction network, we constructed a computational model of minimal protein synthesis consisting of 241 components and 968 reactions that synthesize the Met-Gly-Gly (MGG) peptide based on an Escherichia coli-based reconstituted in vitro protein synthesis system. We performed a simulation using parameters collected primarily from the literature and found that the rate of MGG peptide synthesis becomes nearly constant in minutes, thus achieving a steady state similar to experimental observations. In addition, concentration changes to 70% of the components, including intermediates, reached a plateau in a few minutes. However, the concentration change of each component exhibits several temporal plateaus, or a quasi-stationary state (QSS), before reaching the final plateau. To understand these complex dynamics, we focused on whether the components reached a QSS, mapped the arrangement of components in a QSS in the entire reaction network structure, and investigated time-dependent changes. We found that components in a QSS form clusters that grow over time but not in a linear fashion, and that this process involves the collapse and regrowth of clusters before the formation of a final large single cluster. These observations might commonly occur in other large-scale biological reaction networks. This developed analysis might be useful for understanding large-scale biological reactions by visualizing complex dynamics, thereby extracting the characteristics of the reaction network, including phase transitions.
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13
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Determination of nucleoside triphosphatase activities from measurement of true inorganic phosphate in the presence of labile phosphate compounds. Anal Biochem 2016; 520:62-67. [PMID: 28017740 DOI: 10.1016/j.ab.2016.12.012] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2016] [Revised: 12/10/2016] [Accepted: 12/14/2016] [Indexed: 11/24/2022]
Abstract
One of the most common assays for nucleoside triphosphatase (NTPase) activity entails the quantification of inorganic phosphate (Pi) as a colored phosphomolybdate complex at low pH. While this assay is very sensitive, it is not selective for Pi in the presence of labile organic phosphate compounds (OPCs). Since NTPase activity assays typically require a large excess of OPCs, such as nucleotides, selectivity for Pi in the presence of OPCs is often critical in evaluating enzyme activity. Here we present an improved method for the measurement of enzymatic nucleotide hydrolysis as Pi released, which achieves selectivity for Pi in the presence of OPCs while also avoiding the costs and hazards inherent in other methods for measuring nucleotide hydrolysis. We apply this method to the measurement of ATP hydrolysis by nitrogenase and GTP hydrolysis by elongation factor G (EF-G) in order to demonstrate the broad applicability of our method for the determination of nucleotide hydrolysis in the presence of interfering OPCs.
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14
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Dai X, Zhu M, Warren M, Balakrishnan R, Patsalo V, Okano H, Williamson JR, Fredrick K, Wang YP, Hwa T. Reduction of translating ribosomes enables Escherichia coli to maintain elongation rates during slow growth. Nat Microbiol 2016; 2:16231. [PMID: 27941827 PMCID: PMC5346290 DOI: 10.1038/nmicrobiol.2016.231] [Citation(s) in RCA: 177] [Impact Index Per Article: 22.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2016] [Accepted: 10/17/2016] [Indexed: 01/13/2023]
Abstract
Bacteria growing under different conditions experience a broad range of demand on the rate of protein synthesis, which profoundly affects cellular resource allocation. During fast growth, protein synthesis has long been known to be modulated by adjusting the ribosome content, with the vast majority of ribosomes engaged at a near-maximal rate of elongation. Here, we systematically characterize protein synthesis by Escherichia coli, focusing on slow-growth conditions. We establish that the translational elongation rate decreases as growth slows, exhibiting a Michaelis-Menten dependence on the abundance of the cellular translational apparatus. However, an appreciable elongation rate is maintained even towards zero growth, including the stationary phase. This maintenance, critical for timely protein synthesis in harsh environments, is accompanied by a drastic reduction in the fraction of active ribosomes. Interestingly, well-known antibiotics such as chloramphenicol also cause a substantial reduction in the pool of active ribosomes, instead of slowing down translational elongation as commonly thought.
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Affiliation(s)
- Xiongfeng Dai
- Department of Physics, University of California at San Diego, La Jolla CA 92093-0374
- State Key Laboratory of Protein and Plant Gene Research, School of Life Sciences, Peking University, Beijing 100871, China
| | - Manlu Zhu
- Department of Physics, University of California at San Diego, La Jolla CA 92093-0374
- State Key Laboratory of Protein and Plant Gene Research, School of Life Sciences, Peking University, Beijing 100871, China
| | - Mya Warren
- Department of Physics, University of California at San Diego, La Jolla CA 92093-0374
| | - Rohan Balakrishnan
- Department of Physics, University of California at San Diego, La Jolla CA 92093-0374
- Department of Microbiology and Ohio State Biochemistry Program, the Ohio State University, Columbus OH 43210
| | - Vadim Patsalo
- Department of Integrative Structural and Computational Biology, Department of Chemistry, and The Skaggs Institute for Chemical Biology, The Scripps Research Institute, La Jolla, CA 92037
| | - Hiroyuki Okano
- Department of Physics, University of California at San Diego, La Jolla CA 92093-0374
| | - James R. Williamson
- Department of Integrative Structural and Computational Biology, Department of Chemistry, and The Skaggs Institute for Chemical Biology, The Scripps Research Institute, La Jolla, CA 92037
| | - Kurt Fredrick
- Department of Microbiology and Ohio State Biochemistry Program, the Ohio State University, Columbus OH 43210
| | - Yi-Ping Wang
- State Key Laboratory of Protein and Plant Gene Research, School of Life Sciences, Peking University, Beijing 100871, China
| | - Terence Hwa
- Department of Physics, University of California at San Diego, La Jolla CA 92093-0374
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15
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Ero R, Kumar V, Chen Y, Gao YG. Similarity and diversity of translational GTPase factors EF-G, EF4, and BipA: From structure to function. RNA Biol 2016; 13:1258-1273. [PMID: 27325008 PMCID: PMC5207388 DOI: 10.1080/15476286.2016.1201627] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
Abstract
EF-G, EF4, and BipA are members of the translation factor family of GTPases with a common ribosome binding mode and GTPase activation mechanism. However, topological variations of shared as well as unique domains ensure different roles played by these proteins during translation. Recent X-ray crystallography and cryo-electron microscopy studies have revealed the structural basis for the involvement of EF-G domain IV in securing the movement of tRNAs and mRNA during translocation as well as revealing how the unique C-terminal domains of EF4 and BipA interact with the ribosome and tRNAs contributing to the regulation of translation under certain conditions. EF-G, EF-4, and BipA are intriguing examples of structural variations on a common theme that results in diverse behavior and function. Structural studies of translational GTPase factors have been greatly facilitated by the use of antibiotics, which have revealed their mechanism of action.
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Affiliation(s)
- Rya Ero
- a School of Biological Sciences , Nanyang Technological University , Singapore
| | - Veerendra Kumar
- a School of Biological Sciences , Nanyang Technological University , Singapore.,b Institute of Molecular and Cell Biology, A*STAR , Singapore
| | - Yun Chen
- a School of Biological Sciences , Nanyang Technological University , Singapore
| | - Yong-Gui Gao
- a School of Biological Sciences , Nanyang Technological University , Singapore.,b Institute of Molecular and Cell Biology, A*STAR , Singapore
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16
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Salsi E, Farah E, Netter Z, Dann J, Ermolenko DN. Movement of elongation factor G between compact and extended conformations. J Mol Biol 2014; 427:454-67. [PMID: 25463439 DOI: 10.1016/j.jmb.2014.11.010] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2014] [Revised: 10/28/2014] [Accepted: 11/10/2014] [Indexed: 11/19/2022]
Abstract
Previous structural studies suggested that ribosomal translocation is accompanied by large interdomain rearrangements of elongation factor G (EF-G). Here, we follow the movement of domain IV of EF-G relative to domain II of EF-G using ensemble and single-molecule Förster resonance energy transfer. Our results indicate that ribosome-free EF-G predominantly adopts a compact conformation that can also, albeit infrequently, transition into a more extended conformation in which domain IV moves away from domain II. By contrast, ribosome-bound EF-G predominantly adopts an extended conformation regardless of whether it is interacting with pretranslocation ribosomes or with posttranslocation ribosomes. Our data suggest that ribosome-bound EF-G may also occasionally sample at least one more compact conformation. GTP hydrolysis catalyzed by EF-G does not affect the relative stability of the observed conformations in ribosome-free and ribosome-bound EF-G. Our data support a model suggesting that, upon binding to a pretranslocation ribosome, EF-G moves from a compact to a more extended conformation. This transition is not coupled to but likely precedes both GTP hydrolysis and mRNA/tRNA translocation.
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Affiliation(s)
- Enea Salsi
- Department of Biochemistry and Biophysics and Center for RNA Biology, School of Medicine and Dentistry, University of Rochester, Rochester, NY 14642, USA
| | - Elie Farah
- Department of Biochemistry and Biophysics and Center for RNA Biology, School of Medicine and Dentistry, University of Rochester, Rochester, NY 14642, USA
| | - Zoe Netter
- Department of Biochemistry and Biophysics and Center for RNA Biology, School of Medicine and Dentistry, University of Rochester, Rochester, NY 14642, USA
| | - Jillian Dann
- Department of Biochemistry and Biophysics and Center for RNA Biology, School of Medicine and Dentistry, University of Rochester, Rochester, NY 14642, USA
| | - Dmitri N Ermolenko
- Department of Biochemistry and Biophysics and Center for RNA Biology, School of Medicine and Dentistry, University of Rochester, Rochester, NY 14642, USA.
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17
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MacDougall DD, Gonzalez RL. Translation initiation factor 3 regulates switching between different modes of ribosomal subunit joining. J Mol Biol 2014; 427:1801-18. [PMID: 25308340 DOI: 10.1016/j.jmb.2014.09.024] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2014] [Revised: 09/22/2014] [Accepted: 09/24/2014] [Indexed: 11/30/2022]
Abstract
Ribosomal subunit joining is a key checkpoint in the bacterial translation initiation pathway during which initiation factors (IFs) regulate association of the 30S initiation complex (IC) with the 50S subunit to control formation of a 70S IC that can enter into the elongation stage of protein synthesis. The GTP-bound form of IF2 accelerates subunit joining, whereas IF3 antagonizes subunit joining and plays a prominent role in maintaining translation initiation fidelity. The molecular mechanisms through which IF2 and IF3 collaborate to regulate the efficiency of 70S IC formation, including how they affect the dynamics of subunit joining, remain poorly defined. Here, we use single-molecule fluorescence resonance energy transfer to monitor the interactions between IF2 and the GTPase-associated center (GAC) of the 50S subunit during real-time subunit joining reactions in the absence and presence of IF3. In the presence of IF3, IF2-mediated subunit joining becomes reversible, and subunit joining events cluster into two distinct classes corresponding to formation of shorter- and longer-lifetime 70S ICs. Inclusion of IF3 within the 30S IC was also found to alter the conformation of IF2 relative to the GAC, suggesting that IF3's regulatory effects may stem in part from allosteric modulation of IF2-GAC interactions. The results are consistent with a model in which IF3 can exert control over the efficiency of subunit joining by modulating the conformation of the 30S IC, which in turn influences the formation of stabilizing intersubunit contacts and thus the reaction's degree of reversibility.
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Affiliation(s)
- Daniel D MacDougall
- Columbia University Department of Chemistry, 3000 Broadway, New York, NY 10027, USA
| | - Ruben L Gonzalez
- Columbia University Department of Chemistry, 3000 Broadway, New York, NY 10027, USA.
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18
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Following movement of domain IV of elongation factor G during ribosomal translocation. Proc Natl Acad Sci U S A 2014; 111:15060-5. [PMID: 25288752 DOI: 10.1073/pnas.1410873111] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Translocation of mRNA and tRNAs through the ribosome is catalyzed by a universally conserved elongation factor (EF-G in prokaryotes and EF-2 in eukaryotes). Previous studies have suggested that ribosome-bound EF-G undergoes significant structural rearrangements. Here, we follow the movement of domain IV of EF-G, which is critical for the catalysis of translocation, relative to protein S12 of the small ribosomal subunit using single-molecule FRET. We show that ribosome-bound EF-G adopts distinct conformations corresponding to the pre- and posttranslocation states of the ribosome. Our results suggest that, upon ribosomal translocation, domain IV of EF-G moves toward the A site of the small ribosomal subunit and facilitates the movement of peptidyl-tRNA from the A to the P site. We found no evidence of direct coupling between the observed movement of domain IV of EF-G and GTP hydrolysis. In addition, our results suggest that the pretranslocation conformation of the EF-G-ribosome complex is significantly less stable than the posttranslocation conformation. Hence, the structural rearrangement of EF-G makes a considerable energetic contribution to promoting tRNA translocation.
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19
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Kinz-Thompson CD, Gonzalez RL. smFRET studies of the 'encounter' complexes and subsequent intermediate states that regulate the selectivity of ligand binding. FEBS Lett 2014; 588:3526-38. [PMID: 25066296 PMCID: PMC4779314 DOI: 10.1016/j.febslet.2014.07.013] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2014] [Revised: 07/14/2014] [Accepted: 07/15/2014] [Indexed: 10/25/2022]
Abstract
The selectivity with which a biomolecule can bind its cognate ligand when confronted by the vast array of structurally similar, competing ligands that are present in the cell underlies the fidelity of some of the most fundamental processes in biology. Because they collectively comprise one of only a few methods that can sensitively detect the 'encounter' complexes and subsequent intermediate states that regulate the selectivity of ligand binding, single-molecule fluorescence, and particularly single-molecule fluorescence resonance energy transfer (smFRET), approaches have revolutionized studies of ligand-binding reactions. Here, we describe a widely used smFRET strategy that enables investigations of a large variety of ligand-binding reactions, and discuss two such reactions, aminoacyl-tRNA selection during translation elongation and splice site selection during spliceosome assembly, that highlight both the successes and challenges of smFRET studies of ligand-binding reactions. We conclude by reviewing a number of emerging experimental and computational approaches that are expanding the capabilities of smFRET approaches for studies of ligand-binding reactions and that promise to reveal the mechanisms that control the selectivity of ligand binding with unprecedented resolution.
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Affiliation(s)
| | - Ruben L Gonzalez
- Department of Chemistry, Columbia University, New York, NY 10027, United States.
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20
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Holtkamp W, Wintermeyer W, Rodnina MV. Synchronous tRNA movements during translocation on the ribosome are orchestrated by elongation factor G and GTP hydrolysis. Bioessays 2014; 36:908-18. [PMID: 25118068 DOI: 10.1002/bies.201400076] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
The translocation of tRNAs through the ribosome proceeds through numerous small steps in which tRNAs gradually shift their positions on the small and large ribosomal subunits. The most urgent questions are: (i) whether these intermediates are important; (ii) how the ribosomal translocase, the GTPase elongation factor G (EF-G), promotes directed movement; and (iii) how the energy of GTP hydrolysis is coupled to movement. In the light of recent advances in biophysical and structural studies, we argue that intermediate states of translocation are snapshots of dynamic fluctuations that guide the movement. In contrast to current models of stepwise translocation, kinetic evidence shows that the tRNAs move synchronously on the two ribosomal subunits in a rapid reaction orchestrated by EF-G and GTP hydrolysis. EF-G combines the energy regimes of a GTPase and a motor protein and facilitates tRNA movement by a combination of directed Brownian ratchet and power stroke mechanisms.
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Affiliation(s)
- Wolf Holtkamp
- Department of Physical Biochemistry, Max Planck Institute for Biophysical Chemistry, Göttingen, Germany
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21
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Holtkamp W, Cunha CE, Peske F, Konevega AL, Wintermeyer W, Rodnina MV. GTP hydrolysis by EF-G synchronizes tRNA movement on small and large ribosomal subunits. EMBO J 2014; 33:1073-85. [PMID: 24614227 DOI: 10.1002/embj.201387465] [Citation(s) in RCA: 70] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Elongation factor G (EF-G) promotes the movement of two tRNAs and the mRNA through the ribosome in each cycle of peptide elongation. During translocation, the tRNAs transiently occupy intermediate positions on both small (30S) and large (50S) ribosomal subunits. How EF-G and GTP hydrolysis control these movements is still unclear. We used fluorescence labels that specifically monitor movements on either 30S or 50S subunits in combination with EF-G mutants and translocation-specific antibiotics to investigate timing and energetics of translocation. We show that EF-G-GTP facilitates synchronous movements of peptidyl-tRNA on the two subunits into an early post-translocation state, which resembles a chimeric state identified by structural studies. EF-G binding without GTP hydrolysis promotes only partial tRNA movement on the 50S subunit. However, rapid 30S translocation and the concomitant completion of 50S translocation require GTP hydrolysis and a functional domain 4 of EF-G. Our results reveal two distinct modes for utilizing the energy of EF-G binding and GTP hydrolysis and suggest that coupling of GTP hydrolysis to translocation is mediated through rearrangements of the 30S subunit.
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Affiliation(s)
- Wolf Holtkamp
- Department of Physical Biochemistry, Max Planck Institute for Biophysical Chemistry, Göttingen, Germany
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22
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Structure of the ribosome with elongation factor G trapped in the pretranslocation state. Proc Natl Acad Sci U S A 2013; 110:20994-9. [PMID: 24324137 DOI: 10.1073/pnas.1311423110] [Citation(s) in RCA: 112] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
During protein synthesis, tRNAs and their associated mRNA codons move sequentially on the ribosome from the A (aminoacyl) site to the P (peptidyl) site to the E (exit) site in a process catalyzed by a universally conserved ribosome-dependent GTPase [elongation factor G (EF-G) in prokaryotes and elongation factor 2 (EF-2) in eukaryotes]. Although the high-resolution structure of EF-G bound to the posttranslocation ribosome has been determined, the pretranslocation conformation of the ribosome bound with EF-G and A-site tRNA has evaded visualization owing to the transient nature of this state. Here we use electron cryomicroscopy to determine the structure of the 70S ribosome with EF-G, which is trapped in the pretranslocation state using antibiotic viomycin. Comparison with the posttranslocation ribosome shows that the small subunit of the pretranslocation ribosome is rotated by ∼12° relative to the large subunit. Domain IV of EF-G is positioned in the cleft between the body and head of the small subunit outwardly of the A site and contacts the A-site tRNA. Our findings suggest a model in which domain IV of EF-G promotes the translocation of tRNA from the A to the P site as the small ribosome subunit spontaneously rotates back from the hybrid, rotated state into the nonrotated posttranslocation state.
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23
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Suematsu T, Watanabe O, Kita K, Yokobori SI, Watanabe YI. Arabidopsis thaliana mitochondrial EF-G1 functions in two different translation steps. J Biochem 2013; 155:107-14. [PMID: 24272752 DOI: 10.1093/jb/mvt105] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Translation elongation factor G (EF-G) in bacteria catalyses the translocation of transfer RNA on ribosomes in the elongation step as well as dissociation of post-termination state ribosomes into two subunits in the recycling step. In contrast, the dual functions of EF-G are exclusively divided into two different paralogues in human mitochondria, named EF-G1mt for translocation and EF-G2mt for ribosomal dissociation. Many of the two eukaryotic EF-G paralogues are phylogenetically associated with EF-G1mt and EF-G2mt groups. However, plant paralogues are associated with EF-G1mt and plastid EF-G, not with EF-G2mt. In this study, we phylogenetically and biochemically characterized Arabidopsis thaliana EF-G1mt (AtEF-G1mt) to clarify the factor responsible for the dissociation of ribosomes in plant mitochondria. We showed that eukaryotic EF-G1mts form one monophyletic group separated from bacterial EF-G and are classified into five sister groups. AtEF-G1mt is classified into a different group from its human counterpart. We also demonstrated that AtEF-G1mt catalyses both translocation and ribosomal dissociation, unlike in humans. Meanwhile, AtEF-G1mt is resistant to fusidic acid, an inhibitor of bacterial EF-G. Here, we propose that the functional division is not necessarily conserved among mitochondriate eukaryotes and also that EF-G1mt in organisms lacking EF-G2mt functions in two steps, similar to conventional bacterial EF-G.
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Affiliation(s)
- Takuma Suematsu
- Department of Biomedical Chemistry, Graduate School of Medicine, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, and Department of Applied Life Sciences, School of Life Sciences, Tokyo University of Pharmacy and Life Sciences, 1432-1 Horinouchi, Hachioji-shi, Tokyo 192-0392, Japan
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24
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Gupta A, Mir SS, Saqib U, Biswas S, Vaishya S, Srivastava K, Siddiqi MI, Habib S. The effect of fusidic acid on Plasmodium falciparum elongation factor G (EF-G). Mol Biochem Parasitol 2013; 192:39-48. [PMID: 24211494 DOI: 10.1016/j.molbiopara.2013.10.003] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2013] [Revised: 10/29/2013] [Accepted: 10/29/2013] [Indexed: 11/30/2022]
Abstract
Inhibition of growth of the malaria parasite Plasmodium falciparum by known translation-inhibitory antibiotics has generated interest in understanding their action on the translation apparatus of the two genome containing organelles of the malaria parasite: the mitochondrion and the relic plastid (apicoplast). We report GTPase activity of recombinant EF-G proteins that are targeted to the organelles and further use these to test the effect of the EF-G inhibitor fusidic acid (FA) on the factor-ribosome interface. Our results monitoring locking of EF-G·GDP onto surrogate Escherichia coli ribosomes as well as multi-turnover GTP hydrolysis by the factor indicate that FA has a greater effect on apicoplast EF-G compared to the mitochondrial counterpart. Deletion of a three amino acid (GVG) sequence in the switch I loop that is conserved in proteins of the mitochondrial EF-G1 family and the Plasmodium mitochondrial factor, but is absent in apicoplast EF-G, demonstrated that this motif contributes to differential inhibition of the two EF-Gs by FA. Additionally, the drug thiostrepton, that is known to target the apicoplast and proteasome, enhanced retention of only mitochondrial EF-G on ribosomes providing support for the reported effect of the drug on parasite mitochondrial translation.
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Affiliation(s)
- Ankit Gupta
- Division of Molecular and Structural Biology, CSIR-Central Drug Research Institute, Lucknow, India
| | - Snober S Mir
- Division of Molecular and Structural Biology, CSIR-Central Drug Research Institute, Lucknow, India
| | - Uzma Saqib
- Division of Molecular and Structural Biology, CSIR-Central Drug Research Institute, Lucknow, India
| | - Subir Biswas
- Division of Molecular and Structural Biology, CSIR-Central Drug Research Institute, Lucknow, India
| | - Suniti Vaishya
- Division of Molecular and Structural Biology, CSIR-Central Drug Research Institute, Lucknow, India
| | - Kumkum Srivastava
- Division of Parasitology, CSIR-Central Drug Research Institute, Lucknow, India
| | - Mohammad Imran Siddiqi
- Division of Molecular and Structural Biology, CSIR-Central Drug Research Institute, Lucknow, India
| | - Saman Habib
- Division of Molecular and Structural Biology, CSIR-Central Drug Research Institute, Lucknow, India.
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25
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Peske F, Wintermeyer W. Antibiotics Inhibiting the Translocation Step of Protein Elongation on the Ribosome. Antibiotics (Basel) 2013. [DOI: 10.1002/9783527659685.ch21] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
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26
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Mutagenesis mapping of the protein-protein interaction underlying FusB-type fusidic acid resistance. Antimicrob Agents Chemother 2013; 57:4640-4. [PMID: 23836182 PMCID: PMC3811445 DOI: 10.1128/aac.00198-13] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
FusB-type proteins represent the predominant mechanism of resistance to fusidic acid in staphylococci and act by binding to and modulating the function of the drug target (elongation factor G [EF-G]). To gain further insight into this antibiotic resistance mechanism, we sought to identify residues important for the interaction of FusB with EF-G and thereby delineate the binding interface within the FusB–EF-G complex. Replacement with alanine of any one of four conserved residues within the C-terminal domain of FusB (F156, K184, Y187, and F208) abrogated the ability of the protein to confer resistance to fusidic acid; the purified mutant proteins also lost the ability to bind S. aureus EF-G in vitro. E. coli EF-G, which is not ordinarily able to bind FusB-type proteins, was rendered competent for binding to FusB following deletion of a 3-residue tract (529SNP531) from domain IV of the protein. This study has identified key regions of both FusB and EF-G that are important for the interaction between the proteins, findings which corroborate our previous in silico prediction for the architecture of the complex formed between the resistance protein and the drug target (G. Cox, G. S. Thompson, H. T. Jenkins, F. Peske, A. Savelsbergh, M. V. Rodnina, W. Wintermeyer, S. W. Homans, T. A. Edwards, and A. J. O'Neill, Proc. Natl. Acad. Sci. U. S. A. 109:2102-2107, 2012).
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27
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Cunha CE, Belardinelli R, Peske F, Holtkamp W, Wintermeyer W, Rodnina MV. Dual use of GTP hydrolysis by elongation factor G on the ribosome. ACTA ACUST UNITED AC 2013; 1:e24315. [PMID: 26824016 PMCID: PMC4718068 DOI: 10.4161/trla.24315] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2013] [Revised: 03/08/2013] [Accepted: 03/14/2013] [Indexed: 12/05/2022]
Abstract
Elongation factor G (EF-G) is a GTPase that catalyzes tRNA and mRNA translocation during the elongation cycle of protein synthesis. The GTP-bound state of the factor on the ribosome has been studied mainly with non-hydrolyzable analogs of GTP, which led to controversial conclusions about the role of GTP hydrolysis in translocation. Here we describe a mutant of EF-G in which the catalytic His91 is replaced with Ala. The mutant EF-G does not hydrolyze GTP, but binds GTP with unchanged affinity, allowing us to study the function of the authentic GTP-bound form of EF-G in translocation. Utilizing fluorescent reporter groups attached to the tRNAs, mRNA, and the ribosome we compile the velocity map of translocation seen from different perspectives. The data suggest that GTP hydrolysis accelerates translocation up to 30-fold and facilitates conformational rearrangements of both 30S subunit (presumably the backward rotation of the 30S head) and EF-G that lead to the dissociation of the factor. Thus, EF-G combines the energy regime characteristic for motor proteins, accelerating movement by a conformational change induced by GTP hydrolysis, with that of a switch GTPase, which upon Pi release switches the conformations of EF-G and the ribosome to low affinity, allowing the dissociation of the factor.
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Affiliation(s)
- Carlos E Cunha
- Max Planck Institute for Biophysical Chemistry; Department of Physical Biochemistry; Göttingen, Germany
| | - Riccardo Belardinelli
- Max Planck Institute for Biophysical Chemistry; Department of Physical Biochemistry; Göttingen, Germany
| | - Frank Peske
- Max Planck Institute for Biophysical Chemistry; Department of Physical Biochemistry; Göttingen, Germany
| | - Wolf Holtkamp
- Max Planck Institute for Biophysical Chemistry; Department of Physical Biochemistry; Göttingen, Germany
| | - Wolfgang Wintermeyer
- Max Planck Institute for Biophysical Chemistry; Department of Physical Biochemistry; Göttingen, Germany
| | - Marina V Rodnina
- Max Planck Institute for Biophysical Chemistry; Department of Physical Biochemistry; Göttingen, Germany
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28
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Liu Q, Fredrick K. Contribution of intersubunit bridges to the energy barrier of ribosomal translocation. Nucleic Acids Res 2012; 41:565-74. [PMID: 23161696 PMCID: PMC3592451 DOI: 10.1093/nar/gks1074] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/02/2022] Open
Abstract
In every round of translation elongation, EF-G catalyzes translocation, the movement of tRNAs (and paired codons) to their adjacent binding sites in the ribosome. Previous kinetic studies have shown that the rate of tRNA–mRNA movement is limited by a conformational change in the ribosome termed ‘unlocking’. Although structural studies offer some clues as to what unlocking might entail, the molecular basis of this conformational change remains an open question. In this study, the contribution of intersubunit bridges to the energy barrier of translocation was systematically investigated. Unlike those targeting B2a and B3, mutations that disrupt bridges B1a, B4, B7a and B8 increased the maximal rate of both forward (EF-G dependent) and reverse (spontaneous) translocation. As bridge B1a is predicted to constrain 30S head movement and B4, B7a and B8 are predicted to constrain intersubunit rotation, these data provide evidence that formation of the unlocked (transition) state involves both 30S head movement and intersubunit rotation.
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Affiliation(s)
- Qi Liu
- Ohio State Biochemistry Program, Center for RNA Biology, The Ohio State University, Columbus, OH 43210, USA
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29
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Nyfeler B, Hoepfner D, Palestrant D, Kirby CA, Whitehead L, Yu R, Deng G, Caughlan RE, Woods AL, Jones AK, Barnes SW, Walker JR, Gaulis S, Hauy E, Brachmann SM, Krastel P, Studer C, Riedl R, Estoppey D, Aust T, Movva NR, Wang Z, Salcius M, Michaud GA, McAllister G, Murphy LO, Tallarico JA, Wilson CJ, Dean CR. Identification of elongation factor G as the conserved cellular target of argyrin B. PLoS One 2012; 7:e42657. [PMID: 22970117 PMCID: PMC3438169 DOI: 10.1371/journal.pone.0042657] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2012] [Accepted: 07/10/2012] [Indexed: 11/19/2022] Open
Abstract
Argyrins, produced by myxobacteria and actinomycetes, are cyclic octapeptides with antibacterial and antitumor activity. Here, we identify elongation factor G (EF-G) as the cellular target of argyrin B in bacteria, via resistant mutant selection and whole genome sequencing, biophysical binding studies and crystallography. Argyrin B binds a novel allosteric pocket in EF-G, distinct from the known EF-G inhibitor antibiotic fusidic acid, revealing a new mode of protein synthesis inhibition. In eukaryotic cells, argyrin B was found to target mitochondrial elongation factor G1 (EF-G1), the closest homologue of bacterial EF-G. By blocking mitochondrial translation, argyrin B depletes electron transport components and inhibits the growth of yeast and tumor cells. Further supporting direct inhibition of EF-G1, expression of an argyrin B-binding deficient EF-G1 L693Q variant partially rescued argyrin B-sensitivity in tumor cells. In summary, we show that argyrin B is an antibacterial and cytotoxic agent that inhibits the evolutionarily conserved target EF-G, blocking protein synthesis in bacteria and mitochondrial translation in yeast and mammalian cells.
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Affiliation(s)
- Beat Nyfeler
- Developmental and Molecular Pathways, Novartis Institutes for BioMedical Research, Cambridge, Massachussetts, United States of America
| | - Dominic Hoepfner
- Developmental and Molecular Pathways, Novartis Institutes for BioMedical Research, Basel, Switzerland
| | - Deborah Palestrant
- Center for Proteomic Chemistry, Novartis Institutes for BioMedical Research, Cambridge, Massachussetts, United States of America
| | - Christina A. Kirby
- Center for Proteomic Chemistry, Novartis Institutes for BioMedical Research, Cambridge, Massachussetts, United States of America
| | - Lewis Whitehead
- Global Discovery Chemistry, Novartis Institutes for Biomedical Research, Cambridge, Massachussetts, United States of America
| | - Robert Yu
- Infectious Diseases, Novartis Institutes for BioMedical Research, Emeryville, California, United States of America
| | - Gejing Deng
- Infectious Diseases, Novartis Institutes for BioMedical Research, Emeryville, California, United States of America
| | - Ruth E. Caughlan
- Infectious Diseases, Novartis Institutes for BioMedical Research, Emeryville, California, United States of America
| | - Angela L. Woods
- Infectious Diseases, Novartis Institutes for BioMedical Research, Emeryville, California, United States of America
| | - Adriana K. Jones
- Infectious Diseases, Novartis Institutes for BioMedical Research, Emeryville, California, United States of America
| | - S. Whitney Barnes
- Novartis Institute for Functional Genomics, Novartis Institutes for Biomedical Research, San Diego, California, United States of America
| | - John R. Walker
- Novartis Institute for Functional Genomics, Novartis Institutes for Biomedical Research, San Diego, California, United States of America
| | - Swann Gaulis
- Disease Area Oncology, Novartis Institutes for BioMedical Research, Basel, Switzerland
| | - Ervan Hauy
- Disease Area Oncology, Novartis Institutes for BioMedical Research, Basel, Switzerland
| | - Saskia M. Brachmann
- Disease Area Oncology, Novartis Institutes for BioMedical Research, Basel, Switzerland
| | - Philipp Krastel
- Center for Proteomic Chemistry, Natural Products Unit, Novartis Institutes for BioMedical Research, Basel, Switzerland
| | - Christian Studer
- Developmental and Molecular Pathways, Novartis Institutes for BioMedical Research, Basel, Switzerland
| | - Ralph Riedl
- Developmental and Molecular Pathways, Novartis Institutes for BioMedical Research, Basel, Switzerland
| | - David Estoppey
- Developmental and Molecular Pathways, Novartis Institutes for BioMedical Research, Basel, Switzerland
| | - Thomas Aust
- Developmental and Molecular Pathways, Novartis Institutes for BioMedical Research, Basel, Switzerland
| | - N. Rao Movva
- Developmental and Molecular Pathways, Novartis Institutes for BioMedical Research, Basel, Switzerland
| | - Zuncai Wang
- Developmental and Molecular Pathways, Novartis Institutes for BioMedical Research, Cambridge, Massachussetts, United States of America
| | - Michael Salcius
- Developmental and Molecular Pathways, Novartis Institutes for BioMedical Research, Cambridge, Massachussetts, United States of America
| | - Gregory A. Michaud
- Developmental and Molecular Pathways, Novartis Institutes for BioMedical Research, Cambridge, Massachussetts, United States of America
| | - Gregory McAllister
- Developmental and Molecular Pathways, Novartis Institutes for BioMedical Research, Cambridge, Massachussetts, United States of America
| | - Leon O. Murphy
- Developmental and Molecular Pathways, Novartis Institutes for BioMedical Research, Cambridge, Massachussetts, United States of America
| | - John A. Tallarico
- Developmental and Molecular Pathways, Novartis Institutes for BioMedical Research, Cambridge, Massachussetts, United States of America
| | - Christopher J. Wilson
- Developmental and Molecular Pathways, Novartis Institutes for BioMedical Research, Cambridge, Massachussetts, United States of America
| | - Charles R. Dean
- Infectious Diseases, Novartis Institutes for BioMedical Research, Emeryville, California, United States of America
- * E-mail:
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30
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Rosenblum G, Chen C, Kaur J, Cui X, Goldman YE, Cooperman BS. Real-time assay for testing components of protein synthesis. Nucleic Acids Res 2012; 40:e88. [PMID: 22422844 PMCID: PMC3384345 DOI: 10.1093/nar/gks232] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
We present a flexible, real-time-coupled transcription–translation assay that involves the continuous monitoring of fluorescent Emerald GFP formation. Along with numerical simulation of a reaction kinetics model, the assay permits quantitative estimation of the effects on full-length protein synthesis of various additions, subtractions or substitutions to the protein synthesis machinery. Since the assay uses continuous fluorescence monitoring, it is much simpler and more rapid than other assays of protein synthesis and is compatible with high-throughput formats. Straightforward alterations of the assay permit determination of (i) the fraction of ribosomes in a cell-free protein synthesis kit that is active in full-length protein synthesis and (ii) the relative activities in supporting protein synthesis of modified (e.g. mutated, fluorescent-labeled) exogenous components (ribosomes, amino acid-specific tRNAs) that replace the corresponding endogenous components. Ribosomes containing fluorescent-labeled L11 and tRNAs labeled with fluorophores in the D-loop retain substantial activity. In the latter case, the extent of activity loss correlates with a combination of steric bulk and hydrophobicity of the fluorophore.
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Affiliation(s)
- Gabriel Rosenblum
- The Department of Chemistry, University of Pennsylvania, 231 South 34th Street, Philadelphia, Pennsylvania 19104, USA
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31
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Ribosome clearance by FusB-type proteins mediates resistance to the antibiotic fusidic acid. Proc Natl Acad Sci U S A 2012; 109:2102-7. [PMID: 22308410 DOI: 10.1073/pnas.1117275109] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Resistance to the antibiotic fusidic acid (FA) in the human pathogen Staphylococcus aureus usually results from expression of FusB-type proteins (FusB or FusC). These proteins bind to elongation factor G (EF-G), the target of FA, and rescue translation from FA-mediated inhibition by an unknown mechanism. Here we show that the FusB family are two-domain metalloproteins, the C-terminal domain of which contains a four-cysteine zinc finger with a unique structural fold. This domain mediates a high-affinity interaction with the C-terminal domains of EF-G. By binding to EF-G on the ribosome, FusB-type proteins promote the dissociation of stalled ribosome⋅EF-G⋅GDP complexes that form in the presence of FA, thereby allowing the ribosomes to resume translation. Ribosome clearance by these proteins represents a highly unusual antibiotic resistance mechanism, which appears to be fine-tuned by the relative abundance of FusB-type protein, ribosomes, and EF-G.
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32
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Wang L, Altman RB, Blanchard SC. Insights into the molecular determinants of EF-G catalyzed translocation. RNA (NEW YORK, N.Y.) 2011; 17:2189-2200. [PMID: 22033333 PMCID: PMC3222131 DOI: 10.1261/rna.029033.111] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/30/2011] [Accepted: 09/16/2011] [Indexed: 05/31/2023]
Abstract
Translocation, the directional movement of transfer RNA (tRNA) and messenger RNA (mRNA) substrates on the ribosome during protein synthesis, is regulated by dynamic processes intrinsic to the translating particle. Using single-molecule fluorescence resonance energy transfer (smFRET) imaging, in combination with site-directed mutagenesis of the ribosome and tRNA substrates, we show that peptidyl-tRNA within the aminoacyl site of the bacterial pretranslocation complex can adopt distinct hybrid tRNA configurations resulting from uncoupled motions of the 3'-CCA terminus and the tRNA body. As expected for an on-path translocation intermediate, the hybrid configuration where both the 3'-CCA end and body of peptidyl-tRNA have moved in the direction of translocation exhibits dramatically enhanced puromycin reactivity, an increase in the rate at which EF-G engages the ribosome, and accelerated rates of translocation. These findings provide compelling evidence that the substrate for EF-G catalyzed translocation is an intermediate wherein the bodies of both tRNA substrates adopt hybrid positions within the translating ribosome.
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Affiliation(s)
- Leyi Wang
- Department of Physiology and Biophysics, Weill Cornell Medical College of Cornell University, New York, New York 10065, USA
| | - Roger B. Altman
- Department of Physiology and Biophysics, Weill Cornell Medical College of Cornell University, New York, New York 10065, USA
| | - Scott C. Blanchard
- Department of Physiology and Biophysics, Weill Cornell Medical College of Cornell University, New York, New York 10065, USA
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33
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Mikolajka A, Liu H, Chen Y, Starosta AL, Márquez V, Ivanova M, Cooperman BS, Wilson DN. Differential effects of thiopeptide and orthosomycin antibiotics on translational GTPases. ACTA ACUST UNITED AC 2011; 18:589-600. [PMID: 21609840 DOI: 10.1016/j.chembiol.2011.03.010] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2011] [Revised: 03/07/2011] [Accepted: 03/14/2011] [Indexed: 11/18/2022]
Abstract
The ribosome is a major target in the bacterial cell for antibiotics. Here, we dissect the effects that the thiopeptide antibiotics thiostrepton (ThS) and micrococcin (MiC) as well as the orthosomycin antibiotic evernimicin (Evn) have on translational GTPases. We demonstrate that, like ThS, MiC is a translocation inhibitor, and that the activation by MiC of the ribosome-dependent GTPase activity of EF-G is dependent on the presence of the ribosomal proteins L7/L12 as well as the G' subdomain of EF-G. In contrast, Evn does not inhibit translocation but is a potent inhibitor of back-translocation as well as IF2-dependent 70S-initiation complex formation. Collectively, these results shed insight not only into fundamental aspects of translation but also into the unappreciated specificities of these classes of translational inhibitors.
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34
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Liu CY, Qureshi MT, Lee TH. Interaction strengths between the ribosome and tRNA at various steps of translocation. Biophys J 2011; 100:2201-8. [PMID: 21539788 DOI: 10.1016/j.bpj.2011.03.023] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2011] [Revised: 02/28/2011] [Accepted: 03/24/2011] [Indexed: 10/18/2022] Open
Abstract
Transfer RNA (tRNA) translocates inside the ribosome during translation. We studied the interaction strengths between the ribosome and tRNA at various stages of translocation. We utilized an optical trap to measure the mechanical force to rupture tRNA from the ribosome. We measured the rupture forces of aminoacyl tRNA or peptidyl tRNA mimic from the ribosome in a prepeptidyl transfer state, the pretranslocational state, and the posttranslocational state. In addition, we measured the interaction strength between the ribosome and aminoacyl-tRNA in presence of viomycin. Based on the interaction strengths between the ribosome and tRNA under these conditions, 1), we concluded that tRNA interaction with the 30S subunit is far more important than the interaction with the 50S subunit in the mechanism of translocation; and 2), we propose a mechanism of translocation where the ribosomal ratchet motion, with the aid of EF-G, drives tRNA translocation.
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Affiliation(s)
- Chen-Yu Liu
- Department of Chemistry, The Pennsylvania State University, University Park, Pennsylvania, USA
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35
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Single-molecule fluorescence measurements of ribosomal translocation dynamics. Mol Cell 2011; 42:367-77. [PMID: 21549313 DOI: 10.1016/j.molcel.2011.03.024] [Citation(s) in RCA: 112] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2010] [Revised: 12/01/2010] [Accepted: 03/08/2011] [Indexed: 11/22/2022]
Abstract
We employ single-molecule fluorescence resonance energy transfer (smFRET) to study structural dynamics over the first two elongation cycles of protein synthesis, using ribosomes containing either Cy3-labeled ribosomal protein L11 and A- or P-site Cy5-labeled tRNA or Cy3- and Cy5-labeled tRNAs. Pretranslocation (PRE) complexes demonstrate fluctuations between classical and hybrid forms, with concerted motions of tRNAs away from L11 and from each other when classical complex converts to hybrid complex. EF-G⋅GTP binding to both hybrid and classical PRE complexes halts these fluctuations prior to catalyzing translocation to form the posttranslocation (POST) complex. EF-G dependent translocation from the classical PRE complex proceeds via transient formation of a short-lived hybrid intermediate. A-site binding of either EF-G to the PRE complex or of aminoacyl-tRNA⋅EF-Tu ternary complex to the POST complex markedly suppresses ribosome conformational lability.
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36
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Fabbretti A, Gualerzi CO, Brandi L. How to cope with the quest for new antibiotics. FEBS Lett 2011; 585:1673-81. [PMID: 21513713 DOI: 10.1016/j.febslet.2011.04.029] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2011] [Revised: 04/11/2011] [Accepted: 04/12/2011] [Indexed: 10/18/2022]
Abstract
Since their introduction in therapy, antibiotics have played an essential role in human society, saving millions of lives, allowing safe surgery, organ transplants, cancer therapy. Antibiotics have also helped to elucidate several biological mechanisms and boosted the birth and growth of pharmaceutical companies, generating profits and royalties. The golden era of antibiotics and the scientific and economical drive of big pharma towards these molecules is long gone, but the need for effective antibiotics is increased as their pipelines dwindle and multi-resistant pathogenic strains spread. Here we outline some strategies that could help meet this emergency and list promising new targets.
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Affiliation(s)
- Attilio Fabbretti
- Laboratory of Genetics, Department of Biosciences and Biotechnology, University of Camerino, Camerino (MC), Italy
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37
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Blanchard SC, Cooperman BS, Wilson DN. Probing translation with small-molecule inhibitors. ACTA ACUST UNITED AC 2010; 17:633-45. [PMID: 20609413 DOI: 10.1016/j.chembiol.2010.06.003] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2010] [Revised: 05/14/2010] [Accepted: 06/07/2010] [Indexed: 10/19/2022]
Abstract
The translational apparatus of the bacterial cell remains one of the principal targets of antibiotics for the clinical treatment of infection worldwide. Since the introduction of specific translation inhibitors into clinical practice in the late 1940s, intense efforts have been made to understand their precise mechanisms of action. Such research has often revealed significant and sometimes unexpected insights into many fundamental aspects of the translation mechanism. Central to progress in this area, high-resolution crystal structures of the bacterial ribosome identifying the sites of antibiotic binding are now available, which, together with recent developments in single-molecule and fast-kinetic approaches, provide an integrated view of the dynamic translation process. Assays employing these approaches and focusing on specific steps of the overall translation process are amenable for drug screening. Such assays, coupled with structural studies, have the potential not only to accelerate the discovery of novel and effective antimicrobial agents, but also to refine our understanding of the mechanisms of translation. Antibiotics often stabilize specific functional states of the ribosome and therefore allow distinct translation steps to be dissected in molecular detail.
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Affiliation(s)
- Scott C Blanchard
- Department of Physiology and Biophysics, Weill Cornell Medical College of Cornell University, New York, NY 10065, USA
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38
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Baumann S, Schoof S, Bolten M, Haering C, Takagi M, Shin-ya K, Arndt HD. Molecular Determinants of Microbial Resistance to Thiopeptide Antibiotics. J Am Chem Soc 2010; 132:6973-81. [DOI: 10.1021/ja909317n] [Citation(s) in RCA: 59] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Sascha Baumann
- Fakultät Chemie, Technische Universität Dortmund, Otto-Hahn-Strasse 6, D-44221 Dortmund, Germany, Max-Planck-Institut für Molekulare Physiologie, Otto-Hahn-Strasse 11, D-44227 Dortmund, Germany, and Biomedicinal Information Research Center (BIRC), 2-4-7 Aomi, Koto-ku, Tokyo 135-0064, Japan
| | - Sebastian Schoof
- Fakultät Chemie, Technische Universität Dortmund, Otto-Hahn-Strasse 6, D-44221 Dortmund, Germany, Max-Planck-Institut für Molekulare Physiologie, Otto-Hahn-Strasse 11, D-44227 Dortmund, Germany, and Biomedicinal Information Research Center (BIRC), 2-4-7 Aomi, Koto-ku, Tokyo 135-0064, Japan
| | - Marcel Bolten
- Fakultät Chemie, Technische Universität Dortmund, Otto-Hahn-Strasse 6, D-44221 Dortmund, Germany, Max-Planck-Institut für Molekulare Physiologie, Otto-Hahn-Strasse 11, D-44227 Dortmund, Germany, and Biomedicinal Information Research Center (BIRC), 2-4-7 Aomi, Koto-ku, Tokyo 135-0064, Japan
| | - Claudia Haering
- Fakultät Chemie, Technische Universität Dortmund, Otto-Hahn-Strasse 6, D-44221 Dortmund, Germany, Max-Planck-Institut für Molekulare Physiologie, Otto-Hahn-Strasse 11, D-44227 Dortmund, Germany, and Biomedicinal Information Research Center (BIRC), 2-4-7 Aomi, Koto-ku, Tokyo 135-0064, Japan
| | - Motoki Takagi
- Fakultät Chemie, Technische Universität Dortmund, Otto-Hahn-Strasse 6, D-44221 Dortmund, Germany, Max-Planck-Institut für Molekulare Physiologie, Otto-Hahn-Strasse 11, D-44227 Dortmund, Germany, and Biomedicinal Information Research Center (BIRC), 2-4-7 Aomi, Koto-ku, Tokyo 135-0064, Japan
| | - Kazuo Shin-ya
- Fakultät Chemie, Technische Universität Dortmund, Otto-Hahn-Strasse 6, D-44221 Dortmund, Germany, Max-Planck-Institut für Molekulare Physiologie, Otto-Hahn-Strasse 11, D-44227 Dortmund, Germany, and Biomedicinal Information Research Center (BIRC), 2-4-7 Aomi, Koto-ku, Tokyo 135-0064, Japan
| | - Hans-Dieter Arndt
- Fakultät Chemie, Technische Universität Dortmund, Otto-Hahn-Strasse 6, D-44221 Dortmund, Germany, Max-Planck-Institut für Molekulare Physiologie, Otto-Hahn-Strasse 11, D-44227 Dortmund, Germany, and Biomedicinal Information Research Center (BIRC), 2-4-7 Aomi, Koto-ku, Tokyo 135-0064, Japan
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39
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Clementi N, Chirkova A, Puffer B, Micura R, Polacek N. Atomic mutagenesis reveals A2660 of 23S ribosomal RNA as key to EF-G GTPase activation. Nat Chem Biol 2010; 6:344-51. [PMID: 20348921 DOI: 10.1038/nchembio.341] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2009] [Accepted: 01/21/2010] [Indexed: 11/09/2022]
Abstract
Following ribosomal peptide bond formation, the reaction products, peptidyl-tRNA and deacylated tRNA, need to be translocated from the A- and P-sites to the P- and E-sites, respectively. This process is facilitated by the GTPase elongation factor G (EF-G). The mechanism describing how the ribosome activates GTP hydrolysis is poorly understood in molecular terms. By using an 'atomic mutagenesis' approach, which allows the manipulation of specific functional groups on 23S rRNA nucleotides in the context of the entire ribosome, we disclose the adenine exocyclic N6 amino group at A2660 of the sarcin-ricin loop as a key determinant for triggering GTP hydrolysis on EF-G. We show that the purine pi system-expanding characteristics of the exocyclic functional group at the C6 position of A2660 are essential. We propose that stacking interactions of A2660 with EF-G may act as a molecular trigger to induce repositioning of suspected functional amino acids in EF-G that in turn promote GTP hydrolysis.
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Affiliation(s)
- Nina Clementi
- Innsbruck Biocenter, Medical University Innsbruck, Division of Genomics and RNomics, Innsbruck, Austria
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40
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García-Ortega L, Alvarez-García E, Gavilanes JG, Martínez-del-Pozo A, Joseph S. Cleavage of the sarcin-ricin loop of 23S rRNA differentially affects EF-G and EF-Tu binding. Nucleic Acids Res 2010; 38:4108-19. [PMID: 20215430 PMCID: PMC2896532 DOI: 10.1093/nar/gkq151] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
Ribotoxins are potent inhibitors of protein biosynthesis and inactivate ribosomes from a variety of organisms. The ribotoxin α-sarcin cleaves the large 23S ribosomal RNA (rRNA) at the universally conserved sarcin–ricin loop (SRL) leading to complete inactivation of the ribosome and cellular death. The SRL interacts with translation factors that hydrolyze GTP, and it is important for their binding to the ribosome, but its precise role is not yet understood. We studied the effect of α-sarcin on defined steps of translation by the bacterial ribosome. α-Sarcin-treated ribosomes showed no defects in mRNA and tRNA binding, peptide-bond formation and sparsomycin-dependent translocation. Cleavage of SRL slightly affected binding of elongation factor Tu ternary complex (EF-Tu•GTP•tRNA) to the ribosome. In contrast, the activity of elongation factor G (EF-G) was strongly impaired in α-sarcin-treated ribosomes. Importantly, cleavage of SRL inhibited EF-G binding, and consequently GTP hydrolysis and mRNA–tRNA translocation. These results suggest that the SRL is more critical in EF-G than ternary complex binding to the ribosome implicating different requirements in this region of the ribosome during protein elongation.
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Affiliation(s)
- Lucía García-Ortega
- Department of Chemistry and Biochemistry, University of California at San Diego, La Jolla, CA 92093, USA
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41
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Intramolecular movements in EF-G, trapped at different stages in its GTP hydrolytic cycle, probed by FRET. J Mol Biol 2010; 397:1245-60. [PMID: 20219471 DOI: 10.1016/j.jmb.2010.02.039] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2009] [Revised: 02/19/2010] [Accepted: 02/22/2010] [Indexed: 11/24/2022]
Abstract
Elongation factor G (EF-G) is one of several GTP hydrolytic proteins (GTPases) that cycles repeatedly on and off the ribosome during protein synthesis in bacterial cells. In the functional cycle of EF-G, hydrolysis of guanosine 5'-triphosphate (GTP) is coupled to tRNA-mRNA translocation in ribosomes. GTP hydrolysis induces conformational rearrangements in two switch elements in the G domain of EF-G and other GTPases. These switch elements are thought to initiate the cascade of events that lead to translocation and EF-G cycling between ribosomes. To further define the coupling mechanism, we developed a new fluorescent approach that can detect intramolecular movements in EF-G. We attached a fluorescent probe to the switch I element (sw1) of Escherichia coli EF-G. We monitored the position of the sw1 probe, relative to another fluorescent probe anchored to the GTP substrate or product, by measuring the distance-dependent, Förster resonance energy transfer between the two probes. By analyzing EF-G trapped at five different functional states in its cycle, we could infer the cyclical movements of sw1 within EF-G. Our results provide evidence for conformational changes in sw1, which help to drive the unidirectional EF-G cycle during protein synthesis. More generally, our approach might also serve to define the conformational dynamics of other GTPases with their cellular receptors.
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42
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Suematsu T, Yokobori SI, Morita H, Yoshinari S, Ueda T, Kita K, Takeuchi N, Watanabe YI. A bacterial elongation factor G homologue exclusively functions in ribosome recycling in the spirochaete Borrelia burgdorferi. Mol Microbiol 2010; 75:1445-54. [PMID: 20132446 DOI: 10.1111/j.1365-2958.2010.07067.x] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Translation elongation factor G (EF-G) in bacteria plays two distinct roles in different phases of the translation system. EF-G catalyses the translocation of tRNAs on the ribosome in the elongation step, as well as the dissociation of the post-termination state ribosome into two subunits in the recycling step. In contrast to this conventional view, it has very recently been demonstrated that the dual functions of bacterial EF-G are distributed over two different EF-G paralogues in human mitochondria. In the present study, we show that the same division of roles of EF-G is also found in bacteria. Two EF-G paralogues are found in the spirochaete Borrelia burgdorferi, EF-G1 and EF-G2. We demonstrate that EF-G1 is a translocase, while EF-G2 is an exclusive recycling factor. We further demonstrate that B. burgdorferi EF-G2 does not require GTP hydrolysis for ribosome disassembly, provided that translation initiation factor 3 (IF-3) is present in the reaction. These results indicate that two B. burgdorferi EF-G paralogues are close relatives to mitochondrial EF-G paralogues rather than the conventional bacterial EF-G, in both their phylogenetic and biochemical features.
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Affiliation(s)
- Takuma Suematsu
- Department of Biomedical Chemistry, Graduate School of Medicine, the University of Tokyo, Tokyo, Japan
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43
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Abstract
Protein synthesis is one of the major targets in the cell for antibiotics. This review endeavors to provide a comprehensive "post-ribosome structure" A-Z of the huge diversity of antibiotics that target the bacterial translation apparatus, with an emphasis on correlating the vast wealth of biochemical data with more recently available ribosome structures, in order to understand function. The binding site, mechanism of action, and modes of resistance for 26 different classes of protein synthesis inhibitors are presented, ranging from ABT-773 to Zyvox. In addition to improving our understanding of the process of translation, insight into the mechanism of action of antibiotics is essential to the development of novel and more effective antimicrobial agents to combat emerging bacterial resistance to many clinically-relevant drugs.
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Affiliation(s)
- Daniel N Wilson
- Gene Center and Department of Chemistry and Biochemistry, University of Munich, LMU, Munich, Germany.
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44
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Gao YG, Selmer M, Dunham CM, Weixlbaumer A, Kelley AC, Ramakrishnan V. The structure of the ribosome with elongation factor G trapped in the posttranslocational state. Science 2009; 326:694-9. [PMID: 19833919 PMCID: PMC3763468 DOI: 10.1126/science.1179709] [Citation(s) in RCA: 387] [Impact Index Per Article: 25.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
Elongation factor G (EF-G) is a guanosine triphosphatase (GTPase) that plays a crucial role in the translocation of transfer RNAs (tRNAs) and messenger RNA (mRNA) during translation by the ribosome. We report a crystal structure refined to 3.6 angstrom resolution of the ribosome trapped with EF-G in the posttranslocational state using the antibiotic fusidic acid. Fusidic acid traps EF-G in a conformation intermediate between the guanosine triphosphate and guanosine diphosphate forms. The interaction of EF-G with ribosomal elements implicated in stimulating catalysis, such as the L10-L12 stalk and the L11 region, and of domain IV of EF-G with the tRNA at the peptidyl-tRNA binding site (P site) and with mRNA shed light on the role of these elements in EF-G function. The stabilization of the mobile stalks of the ribosome also results in a more complete description of its structure.
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Affiliation(s)
- Yong-Gui Gao
- MRC Laboratory of Molecular Biology, Hills Road, Cambridge CB2 0QH, United Kingdom
| | | | | | | | - Ann C. Kelley
- MRC Laboratory of Molecular Biology, Hills Road, Cambridge CB2 0QH, United Kingdom
| | - V. Ramakrishnan
- MRC Laboratory of Molecular Biology, Hills Road, Cambridge CB2 0QH, United Kingdom
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45
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Starosta AL, Qin H, Mikolajka A, Leung GYC, Schwinghammer K, Chen DYK, Cooperman BS, Wilson DN. Identification of distinct thiopeptide-antibiotic precursor lead compounds using translation machinery assays. CHEMISTRY & BIOLOGY 2009; 16:1087-96. [PMID: 19875082 PMCID: PMC3117328 DOI: 10.1016/j.chembiol.2009.09.016] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/28/2009] [Revised: 09/06/2009] [Accepted: 09/10/2009] [Indexed: 11/20/2022]
Abstract
Most thiopeptide antibiotics target the translational machinery: thiostrepton (ThS) and nosiheptide (NoS) target the ribosome and inhibit translation factor function, whereas GE2270A/T binds to the elongation factor EF-Tu and prevents ternary complex formation. We have used several in vitro translational machinery assays to screen a library of thiopeptide antibiotic precursor compounds and identified four families of precursor compounds that are either themselves inhibitory or are able to relieve the inhibitory effects of ThS, NoS, or GE2270T. Some of these precursors represent distinct compounds with respect to their ability to bind to ribosomes. The results not only provide insight into the mechanism of action of thiopeptide compounds but also demonstrate the potential of such assays for identifying lead compounds that might be missed using conventional inhibitory screening protocols.
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Affiliation(s)
- Agata L. Starosta
- Gene Center and Department of Chemistry and Biochemistry
- Center for Integrated Protein Science Munich (CiPSM), University of Munich, LMU, Feodor Lynen Str. 25, 81377, Munich, Germany
| | - Haiou Qin
- Department of Chemistry, University of Pennsylvania, Philadelphia, PA 19104-6323, USA
| | - Aleksandra Mikolajka
- Gene Center and Department of Chemistry and Biochemistry
- Center for Integrated Protein Science Munich (CiPSM), University of Munich, LMU, Feodor Lynen Str. 25, 81377, Munich, Germany
| | - Gulice Y. C. Leung
- Chemical Synthesis Laboratory@Biopolis, Institute of Chemical and Engineering Sciences (ICES), Agency for Science, Technology and Research (A*STAR), 11 Biopolis Way, The Helios Block, #03–08 Singapore 138667
| | - Kathrin Schwinghammer
- Gene Center and Department of Chemistry and Biochemistry
- Center for Integrated Protein Science Munich (CiPSM), University of Munich, LMU, Feodor Lynen Str. 25, 81377, Munich, Germany
| | - David Y.-K. Chen
- Chemical Synthesis Laboratory@Biopolis, Institute of Chemical and Engineering Sciences (ICES), Agency for Science, Technology and Research (A*STAR), 11 Biopolis Way, The Helios Block, #03–08 Singapore 138667
| | - Barry S. Cooperman
- Department of Chemistry, University of Pennsylvania, Philadelphia, PA 19104-6323, USA
| | - Daniel N. Wilson
- Gene Center and Department of Chemistry and Biochemistry
- Center for Integrated Protein Science Munich (CiPSM), University of Munich, LMU, Feodor Lynen Str. 25, 81377, Munich, Germany
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46
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Shan SO, Schmid SL, Zhang X. Signal recognition particle (SRP) and SRP receptor: a new paradigm for multistate regulatory GTPases. Biochemistry 2009; 48:6696-704. [PMID: 19469550 PMCID: PMC2883566 DOI: 10.1021/bi9006989] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The GTP-binding proteins or GTPases comprise a superfamily of proteins that provide molecular switches in numerous cellular processes. The "GTPase switch" paradigm, in which a GTPase acts as a bimodal switch that is turned "on" and "off" by external regulatory factors, has been used to interpret the regulatory mechanism of many GTPases for more than two decades. Nevertheless, recent work has unveiled an emerging class of "multistate" regulatory GTPases that do not adhere to this classical paradigm. Instead of relying on external nucleotide exchange factors or GTPase activating proteins to switch between the on and off states, these GTPases have the intrinsic ability to exchange nucleotides and to sense and respond to upstream and downstream factors. In contrast to the bimodal nature of the GTPase switch, these GTPases undergo multiple conformational rearrangements, allowing multiple regulatory points to be built into a complex biological process to ensure the efficiency and fidelity of the pathway. We suggest that these multistate regulatory GTPases are uniquely suited to provide spatial and temporal control of complex cellular pathways that require multiple molecular events to occur in a highly coordinated fashion.
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Affiliation(s)
- Shu-ou Shan
- Division of Chemistry and Chemical Engineering, California Institute of Technology, 1200 East California Boulevard, Pasadena, California 91125, USA.
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47
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Qin H, Grigoriadou C, Cooperman BS. Interaction of IF2 with the ribosomal GTPase-associated center during 70S initiation complex formation. Biochemistry 2009; 48:4699-706. [PMID: 19366171 DOI: 10.1021/bi900222e] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Addition of an Escherichia coli 50S subunit (50S(Cy5)) containing a Cy5-labeled L11 N-terminal domain (L11-NTD) within the GTPase-associated center (GAC) to an E. coli 30S initiation complex (30SIC(Cy3)) containing Cy3-labeled initiation factor 2 complexed with GTP leads to rapid development of a FRET signal during formation of the 70S initiation complex (70SIC). Initiation factor 2 (IF2) and elongation factor G (EF-G) induce similar changes in ribosome structure. Here we show that such similarities are maintained on a dynamic level as well. Thus, movement of IF2 toward L11-NTD after initial 70S ribosome formation follows GTP hydrolysis and precedes P(i) release, paralleling movement of EF-G following its binding to the ribosome [Seo, H., et al. (2006) Biochemistry 45, 2504-2514], and in both cases, the rate of such movement is slowed if GTP hydrolysis is prevented. The 30SIC(Cy3):50S(Cy5) FRET signal also provides a sensitive probe of the ability of initiation factor 3 to discriminate between a canonical and a noncanonical initiation codon during 70SIC formation. We employ Bacillus stearothermophilus IF2 as a substitute for E. coli IF2 to take advantage of the higher stability of the complexes it forms with E. coli ribosomes. While Bst-IF2 is fully functional in formation of E. coli 70SIC, relative reactivities toward dipeptide formation of 70SICs formed with the two IF2s suggest that the Bst-IF2.GDP complex is more difficult to displace from the GAC than the E. coli IF2.GDP complex.
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Affiliation(s)
- Haiou Qin
- Department of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104-6323, USA
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48
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Savelsbergh A, Rodnina MV, Wintermeyer W. Distinct functions of elongation factor G in ribosome recycling and translocation. RNA (NEW YORK, N.Y.) 2009; 15:772-80. [PMID: 19324963 PMCID: PMC2673078 DOI: 10.1261/rna.1592509] [Citation(s) in RCA: 93] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/26/2009] [Accepted: 02/09/2009] [Indexed: 05/22/2023]
Abstract
Elongation factor G (EF-G) promotes the translocation step in bacterial protein synthesis and, together with ribosome recycling factor (RRF), the disassembly of the post-termination ribosome. Unlike translocation, ribosome disassembly strictly requires GTP hydrolysis by EF-G. Here we report that ribosome disassembly is strongly inhibited by vanadate, an analog of inorganic phosphate (Pi), indicating that Pi release is required for ribosome disassembly. In contrast, the function of EF-G in single-round translocation is not affected by vanadate, while the turnover reaction is strongly inhibited. We also show that the antibiotic fusidic acid blocks ribosome disassembly by EF-G/RRF at a 1000-fold lower concentration than required for the inhibition of EF-G turnover in vitro and close to the effective inhibitory concentration in vivo, suggesting that the antimicrobial activity of fusidic acid is primarily due to the direct inhibition of ribosome recycling. Our results indicate that conformational coupling between EF-G and the ribosome is principally different in translocation and ribosome disassembly. Pi release is not required for the mechanochemical function of EF-G in translocation, whereas the interactions between RRF and EF-G introduce tight coupling between the conformational change of EF-G induced by Pi release and ribosome disassembly.
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Affiliation(s)
- Andreas Savelsbergh
- Institute of Molecular Biology, University of Witten/Herdecke, 58448 Witten, Germany
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Stapulionis R, Wang Y, Dempsey GT, Khudaravalli R, Nielsen KM, Cooperman BS, Goldman YE, Knudsen CR. Fast in vitro translation system immobilized on a surface via specific biotinylation of the ribosome. Biol Chem 2008; 389:1239-49. [PMID: 18713011 DOI: 10.1515/bc.2008.141] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
The ribosome is the macromolecular machine responsible for translating the genetic code into polypeptide chains. Despite impressive structural and kinetic studies of the translation process, a number of challenges remain with respect to understanding the dynamic properties of the translation apparatus. Single-molecule techniques hold the potential of characterizing the structural and mechanical properties of macromolecules during their functional cycles in real time. These techniques often necessitate the specific coupling of biologically active molecules to a surface. Here, we describe a procedure for such coupling of functionally active ribosomes that permits single-molecule studies of protein synthesis. Oxidation with NaIO4 at the 3' end of 23S rRNA and subsequent reaction with a biotin hydrazide produces biotinylated 70S ribosomes, which can be immobilized on a streptavidin-coated surface. The surface-attached ribosomes are fully active in poly(U) translation in vitro, synthesizing poly(Phe) at a rate of 3-6 peptide bonds/s per active ribosome at 37 degrees C. Specificity of binding of biotinylated ribosomes to a streptavidin-coated quartz surface was confirmed by observation of individual fluorescently labeled, biotinylated 70S ribosomes, using total internal reflection fluorescence microscopy. Functional interactions of the immobilized ribosomes with various components of the protein synthesis apparatus are shown by use of surface plasmon resonance.
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Affiliation(s)
- Romualdas Stapulionis
- Department of Physics and Astronomy, Aarhus University, Ny Munkegade, Bldg. 1520, DK-8000 Arhus C, Denmark
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Mutations in conserved helix 69 of 23S rRNA of Thermus thermophilus that affect capreomycin resistance but not posttranscriptional modifications. J Bacteriol 2008; 190:7754-61. [PMID: 18805973 DOI: 10.1128/jb.00984-08] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Translocation during the elongation phase of protein synthesis involves the relative movement of the 30S and 50S ribosomal subunits. This movement is the target of tuberactinomycin antibiotics. Here, we describe the isolation and characterization of mutants of Thermus thermophilus selected for resistance to the tuberactinomycin antibiotic capreomycin. Two base substitutions, A1913U and mU1915G, and a single base deletion, DeltamU1915, were identified in helix 69 of 23S rRNA, a structural element that forms part of an interribosomal subunit bridge with the decoding center of 16S rRNA, the site of previously reported capreomycin resistance base substitutions. Capreomycin resistance in other bacteria has been shown to result from inactivation of the TlyA methyltransferase which 2'-O methylates C1920 of 23S rRNA. Inactivation of the tlyA gene in T. thermophilus does not affect its sensitivity to capreomycin. Finally, none of the mutations in helix 69 interferes with methylation at C1920 or with pseudouridylation at positions 1911 and 1917. We conclude that the resistance phenotype is a consequence of structural changes introduced by the mutations.
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