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Cruz-Navarrete FA, Griffin WC, Chan YC, Martin MI, Alejo JL, Natchiar SK, Knudson IJ, Altman RB, Schepartz A, Miller SJ, Blanchard SC. β-amino acids reduce ternary complex stability and alter the translation elongation mechanism. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.02.24.581891. [PMID: 38464221 PMCID: PMC10925103 DOI: 10.1101/2024.02.24.581891] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/12/2024]
Abstract
Templated synthesis of proteins containing non-natural amino acids (nnAAs) promises to vastly expand the chemical space available to biological therapeutics and materials. Existing technologies limit the identity and number of nnAAs than can be incorporated into a given protein. Addressing these bottlenecks requires deeper understanding of the mechanism of messenger RNA (mRNA) templated protein synthesis and how this mechanism is perturbed by nnAAs. Here we examine the impact of both monomer backbone and side chain on formation and ribosome-utilization of the central protein synthesis substate: the ternary complex of native, aminoacylated transfer RNA (aa-tRNA), thermally unstable elongation factor (EF-Tu), and GTP. By performing ensemble and single-molecule fluorescence resonance energy transfer (FRET) measurements, we reveal the dramatic effect of monomer backbone on ternary complex formation and protein synthesis. Both the (R) and (S)-β2 isomers of Phe disrupt ternary complex formation to levels below in vitro detection limits, while (R)- and (S)-β3-Phe reduce ternary complex stability by approximately one order of magnitude. Consistent with these findings, (R)- and (S)-β2-Phe-charged tRNAs were not utilized by the ribosome, while (R)- and (S)-β3-Phe stereoisomers were utilized inefficiently. The reduced affinities of both species for EF-Tu ostensibly bypassed the proofreading stage of mRNA decoding. (R)-β3-Phe but not (S)-β3-Phe also exhibited order of magnitude defects in the rate of substrate translocation after mRNA decoding, in line with defects in peptide bond formation that have been observed for D-α-Phe. We conclude from these findings that non-natural amino acids can negatively impact the translation mechanism on multiple fronts and that the bottlenecks for improvement must include consideration of the efficiency and stability of ternary complex formation.
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Affiliation(s)
- F. Aaron Cruz-Navarrete
- Department of Structural Biology, St Jude Children’s Research Hospital, Memphis, Tennessee, USA
- Department of Chemical Biology & Therapeutics, St Jude Children’s Research Hospital, Memphis, Tennessee, USA
| | - Wezley C. Griffin
- Department of Structural Biology, St Jude Children’s Research Hospital, Memphis, Tennessee, USA
- Department of Chemical Biology & Therapeutics, St Jude Children’s Research Hospital, Memphis, Tennessee, USA
| | - Yuk-Cheung Chan
- Department of Chemistry, Yale University, New Haven, Connecticut, USA
| | - Maxwell I. Martin
- Department of Structural Biology, St Jude Children’s Research Hospital, Memphis, Tennessee, USA
- Department of Chemical Biology & Therapeutics, St Jude Children’s Research Hospital, Memphis, Tennessee, USA
| | - Jose L. Alejo
- Department of Structural Biology, St Jude Children’s Research Hospital, Memphis, Tennessee, USA
- Department of Chemical Biology & Therapeutics, St Jude Children’s Research Hospital, Memphis, Tennessee, USA
| | - S. Kundhavai Natchiar
- Department of Structural Biology, St Jude Children’s Research Hospital, Memphis, Tennessee, USA
- Department of Chemical Biology & Therapeutics, St Jude Children’s Research Hospital, Memphis, Tennessee, USA
| | - Isaac J. Knudson
- College of Chemistry, University of California, Berkeley, California, USA
| | - Roger B. Altman
- Department of Structural Biology, St Jude Children’s Research Hospital, Memphis, Tennessee, USA
- Department of Chemical Biology & Therapeutics, St Jude Children’s Research Hospital, Memphis, Tennessee, USA
| | - Alanna Schepartz
- College of Chemistry, University of California, Berkeley, California, USA
- Molecular and Cell Biology, University of California, Berkeley, CA 94720, USA
- California Institute for Quantitative Biosciences, University of California, Berkeley, CA 94720, USA
- Chan Zuckerberg Biohub, San Francisco, CA 94158, USA
- Innovation Investigator, ARC Institute, Palo Alto, CA 94304, USA
| | - Scott J. Miller
- Department of Chemistry, Yale University, New Haven, Connecticut, USA
| | - Scott C. Blanchard
- Department of Structural Biology, St Jude Children’s Research Hospital, Memphis, Tennessee, USA
- Department of Chemical Biology & Therapeutics, St Jude Children’s Research Hospital, Memphis, Tennessee, USA
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2
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Tang-Siegel GG. Human Serum Mediated Bacteriophage Life Cycle Switch in Aggregatibacter actinomycetemcomitans Is Linked to Pyruvate Dehydrogenase Complex. Life (Basel) 2023; 13:436. [PMID: 36836793 PMCID: PMC9959103 DOI: 10.3390/life13020436] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2022] [Revised: 01/30/2023] [Accepted: 02/01/2023] [Indexed: 02/09/2023] Open
Abstract
Antimicrobial resistance is rising as a major global public health threat and antibiotic resistance genes are widely spread among species, including human oral pathogens, e.g., Aggregatibacter actinomycetemcomitans. This Gram-negative, capnophilic, facultative anaerobe is well recognized as a causative agent leading to periodontal diseases, as well as seriously systemic infections including endocarditis. A. actinomycetemcomitans has also evolved mechanisms against complement-mediated phagocytosis and resiliently survives in serum-rich in vivo environments, i.e., inflamed periodontal pockets and blood circulations. This bacterium, however, demonstrated increasing sensitivity to human serum, when being infected by a pseudolysogenic bacteriophage S1249, which switched to the lytic state as a response to human serum. Concomitantly, the pyruvate dehydrogenase complex (PDHc), which is composed of multiple copies of three enzymes (E1, E2, and E3) and oxidatively decarboxylates pyruvate to acetyl-CoA available for tricarboxylic acid (TCA) cycle, was found up-regulated 10-fold in the bacterial lysogen after human serum exposure. The data clearly indicated that certain human serum components induced phage virion replication and egress, resulting in bacterial lysis. Phage manipulation of bacterial ATP production through regulation of PDHc, a gatekeeper linking glycolysis to TCA cycle through aerobic respiration, suggests that a more efficient energy production and delivery system is required for phage progeny replication and release in this in vivo environment. Insights into bacteriophage regulation of bacterial fitness in a mimic in vivo condition will provide alternative strategies to control bacterial infection, in addition to antibiotics.
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Affiliation(s)
- Gaoyan Grace Tang-Siegel
- Department of Molecular Physiology and Biophysics, College of Medicine, University of Vermont and State Agricultural College, Burlington, VT 05405, USA
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3
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Wang J, Yashiro Y, Sakaguchi Y, Suzuki T, Tomita K. Mechanistic insights into tRNA cleavage by a contact-dependent growth inhibitor protein and translation factors. Nucleic Acids Res 2022; 50:4713-4731. [PMID: 35411396 PMCID: PMC9071432 DOI: 10.1093/nar/gkac228] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2022] [Revised: 03/21/2022] [Accepted: 03/25/2022] [Indexed: 12/04/2022] Open
Abstract
Contact-dependent growth inhibition is a mechanism of interbacterial competition mediated by delivery of the C-terminal toxin domain of CdiA protein (CdiA–CT) into neighboring bacteria. The CdiA–CT of enterohemorrhagic Escherichia coli EC869 (CdiA–CTEC869) cleaves the 3′-acceptor regions of specific tRNAs in a reaction that requires the translation factors Tu/Ts and GTP. Here, we show that CdiA–CTEC869 has an intrinsic ability to recognize a specific sequence in substrate tRNAs, and Tu:Ts complex promotes tRNA cleavage by CdiA–CTEC869. Uncharged and aminoacylated tRNAs (aa-tRNAs) were cleaved by CdiA–CTEC869 to the same extent in the presence of Tu/Ts, and the CdiA–CTEC869:Tu:Ts:tRNA(aa-tRNA) complex formed in the presence of GTP. CdiA–CTEC869 interacts with domain II of Tu, thereby preventing the 3′-moiety of tRNA to bind to Tu as in canonical Tu:GTP:aa-tRNA complexes. Superimposition of the Tu:GTP:aa-tRNA structure onto the CdiA–CTEC869:Tu structure suggests that the 3′-portion of tRNA relocates into the CdiA–CTEC869 active site, located on the opposite side to the CdiA–CTEC869 :Tu interface, for tRNA cleavage. Thus, CdiA–CTEC869 is recruited to Tu:GTP:Ts, and CdiA–CT:Tu:GTP:Ts recognizes substrate tRNAs and cleaves them. Tu:GTP:Ts serves as a reaction scaffold that increases the affinity of CdiA–CTEC869 for substrate tRNAs and induces a structural change of tRNAs for efficient cleavage by CdiA–CTEC869.
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Affiliation(s)
- Jing Wang
- Department of Computational Biology and Medical Sciences, Graduate School of Frontier Sciences, The University of Tokyo, Kashiwa,Chiba277-8562, Japan
| | - Yuka Yashiro
- Department of Computational Biology and Medical Sciences, Graduate School of Frontier Sciences, The University of Tokyo, Kashiwa,Chiba277-8562, Japan
| | - Yuriko Sakaguchi
- Department of Chemistry and Biotechnology, Graduate School of Engineering, The University of Tokyo, Bunkyo-ku, Tokyo 113-8656, Japan
| | - Tsutomu Suzuki
- Department of Chemistry and Biotechnology, Graduate School of Engineering, The University of Tokyo, Bunkyo-ku, Tokyo 113-8656, Japan
| | - Kozo Tomita
- Department of Computational Biology and Medical Sciences, Graduate School of Frontier Sciences, The University of Tokyo, Kashiwa,Chiba277-8562, Japan
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4
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Abstract
Peptide-chain elongation during protein synthesis entails sequential aminoacyl-tRNA selection and translocation reactions that proceed rapidly (2-20 per second) and with a low error rate (around 10-3 to 10-5 at each step) over thousands of cycles1. The cadence and fidelity of ribosome transit through mRNA templates in discrete codon increments is a paradigm for movement in biological systems that must hold for diverse mRNA and tRNA substrates across domains of life. Here we use single-molecule fluorescence methods to guide the capture of structures of early translocation events on the bacterial ribosome. Our findings reveal that the bacterial GTPase elongation factor G specifically engages spontaneously achieved ribosome conformations while in an active, GTP-bound conformation to unlock and initiate peptidyl-tRNA translocation. These findings suggest that processes intrinsic to the pre-translocation ribosome complex can regulate the rate of protein synthesis, and that energy expenditure is used later in the translocation mechanism than previously proposed.
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5
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Elongation factor-Tu can repetitively engage aminoacyl-tRNA within the ribosome during the proofreading stage of tRNA selection. Proc Natl Acad Sci U S A 2020; 117:3610-3620. [PMID: 32024753 PMCID: PMC7035488 DOI: 10.1073/pnas.1904469117] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Elongation factor Tu (EF-Tu) facilitates rapid and accurate selection of aminoacyl-tRNA (aa-tRNA) by the bacterial ribosome during protein synthesis. We show that EF-Tu dissociates from the ribosome as aa-tRNA navigates the accommodation corridor en route to peptide bond formation. We find that EF-Tu’s release from the ribosome during aa-tRNA selection can be reversible. We also demonstrate that new ternary complex formation, accompanied by futile cycles of GTP hydrolysis, can occur on aa-tRNA bound within the ribosome. These findings inform on the decoding mechanism, the contributions of EF-Tu to the fidelity of translation, and the potential consequences of reduced rates of peptide bond formation on cellular physiology. The substrate for ribosomes actively engaged in protein synthesis is a ternary complex of elongation factor Tu (EF-Tu), aminoacyl-tRNA (aa-tRNA), and GTP. EF-Tu plays a critical role in mRNA decoding by increasing the rate and fidelity of aa-tRNA selection at each mRNA codon. Here, using three-color single-molecule fluorescence resonance energy transfer imaging and molecular dynamics simulations, we examine the timing and role of conformational events that mediate the release of aa-tRNA from EF-Tu and EF-Tu from the ribosome after GTP hydrolysis. Our investigations reveal that conformational changes in EF-Tu coordinate the rate-limiting passage of aa-tRNA through the accommodation corridor en route to the peptidyl transferase center of the large ribosomal subunit. Experiments using distinct inhibitors of the accommodation process further show that aa-tRNA must at least partially transit the accommodation corridor for EF-Tu⋅GDP to release. aa-tRNAs failing to undergo peptide bond formation at the end of accommodation corridor passage after EF-Tu release can be reengaged by EF-Tu⋅GTP from solution, coupled to GTP hydrolysis. These observations suggest that additional rounds of ternary complex formation can occur on the ribosome during proofreading, particularly when peptide bond formation is slow, which may serve to increase both the rate and fidelity of protein synthesis at the expense of GTP hydrolysis.
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6
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Mihăşan M, Babii C, Aslebagh R, Channaveerappa D, Dupree EJ, Darie CC. Exploration of Nicotine Metabolism in Paenarthrobacter nicotinovorans pAO1 by Microbial Proteomics. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2019; 1140:515-529. [DOI: 10.1007/978-3-030-15950-4_30] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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7
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Flis J, Holm M, Rundlet EJ, Loerke J, Hilal T, Dabrowski M, Bürger J, Mielke T, Blanchard SC, Spahn CMT, Budkevich TV. tRNA Translocation by the Eukaryotic 80S Ribosome and the Impact of GTP Hydrolysis. Cell Rep 2018; 25:2676-2688.e7. [PMID: 30517857 PMCID: PMC6314685 DOI: 10.1016/j.celrep.2018.11.040] [Citation(s) in RCA: 41] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2018] [Revised: 09/14/2018] [Accepted: 11/09/2018] [Indexed: 01/04/2023] Open
Abstract
Translocation moves the tRNA2⋅mRNA module directionally through the ribosome during the elongation phase of protein synthesis. Although translocation is known to entail large conformational changes within both the ribosome and tRNA substrates, the orchestrated events that ensure the speed and fidelity of this critical aspect of the protein synthesis mechanism have not been fully elucidated. Here, we present three high-resolution structures of intermediates of translocation on the mammalian ribosome where, in contrast to bacteria, ribosomal complexes containing the translocase eEF2 and the complete tRNA2⋅mRNA module are trapped by the non-hydrolyzable GTP analog GMPPNP. Consistent with the observed structures, single-molecule imaging revealed that GTP hydrolysis principally facilitates rate-limiting, final steps of translocation, which are required for factor dissociation and which are differentially regulated in bacterial and mammalian systems by the rates of deacyl-tRNA dissociation from the E site.
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Affiliation(s)
- Julia Flis
- Institut für Medizinische Physik und Biophysik, Charité - Universitätsmedizin Berlin, Charitéplatz 1, 10117 Berlin, Germany
| | - Mikael Holm
- Department of Physiology and Biophysics, Weill Cornell Medicine, New York, NY, USA
| | - Emily J Rundlet
- Department of Physiology and Biophysics, Weill Cornell Medicine, New York, NY, USA; Tri-Institutional PhD Program in Chemical Biology, Weill Cornell Medicine, New York, NY, USA
| | - Justus Loerke
- Institut für Medizinische Physik und Biophysik, Charité - Universitätsmedizin Berlin, Charitéplatz 1, 10117 Berlin, Germany
| | - Tarek Hilal
- Institut für Medizinische Physik und Biophysik, Charité - Universitätsmedizin Berlin, Charitéplatz 1, 10117 Berlin, Germany
| | - Marylena Dabrowski
- Institut für Medizinische Physik und Biophysik, Charité - Universitätsmedizin Berlin, Charitéplatz 1, 10117 Berlin, Germany
| | - Jörg Bürger
- Institut für Medizinische Physik und Biophysik, Charité - Universitätsmedizin Berlin, Charitéplatz 1, 10117 Berlin, Germany; UltraStrukturNetzwerk, Max Planck Institute for Molecular Genetics, 14195 Berlin, Germany
| | - Thorsten Mielke
- UltraStrukturNetzwerk, Max Planck Institute for Molecular Genetics, 14195 Berlin, Germany
| | - Scott C Blanchard
- Department of Physiology and Biophysics, Weill Cornell Medicine, New York, NY, USA; Tri-Institutional PhD Program in Chemical Biology, Weill Cornell Medicine, New York, NY, USA.
| | - Christian M T Spahn
- Institut für Medizinische Physik und Biophysik, Charité - Universitätsmedizin Berlin, Charitéplatz 1, 10117 Berlin, Germany.
| | - Tatyana V Budkevich
- Institut für Medizinische Physik und Biophysik, Charité - Universitätsmedizin Berlin, Charitéplatz 1, 10117 Berlin, Germany.
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8
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Neuwald AF, Aravind L, Altschul SF. Inferring joint sequence-structural determinants of protein functional specificity. eLife 2018; 7. [PMID: 29336305 PMCID: PMC5770160 DOI: 10.7554/elife.29880] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2017] [Accepted: 12/22/2017] [Indexed: 01/05/2023] Open
Abstract
Residues responsible for allostery, cooperativity, and other subtle but functionally important interactions remain difficult to detect. To aid such detection, we employ statistical inference based on the assumption that residues distinguishing a protein subgroup from evolutionarily divergent subgroups often constitute an interacting functional network. We identify such networks with the aid of two measures of statistical significance. One measure aids identification of divergent subgroups based on distinguishing residue patterns. For each subgroup, a second measure identifies structural interactions involving pattern residues. Such interactions are derived either from atomic coordinates or from Direct Coupling Analysis scores, used as surrogates for structural distances. Applying this approach to N-acetyltransferases, P-loop GTPases, RNA helicases, synaptojanin-superfamily phosphatases and nucleases, and thymine/uracil DNA glycosylases yielded results congruent with biochemical understanding of these proteins, and also revealed striking sequence-structural features overlooked by other methods. These and similar analyses can aid the design of drugs targeting allosteric sites.
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Affiliation(s)
- Andrew F Neuwald
- Institute for Genome Sciences, University of Maryland School of Medicine, Baltimore, United States.,Department of Biochemistry and Molecular Biology, University of Maryland School of Medicine, Baltimore, United States
| | - L Aravind
- National Center for Biotechnology Information, National Library of Medicine, National Institutes of Health, Bethesda, United States
| | - Stephen F Altschul
- National Center for Biotechnology Information, National Library of Medicine, National Institutes of Health, Bethesda, United States
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9
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Michalska K, Gucinski GC, Garza-Sánchez F, Johnson PM, Stols LM, Eschenfeldt WH, Babnigg G, Low DA, Goulding CW, Joachimiak A, Hayes CS. Structure of a novel antibacterial toxin that exploits elongation factor Tu to cleave specific transfer RNAs. Nucleic Acids Res 2017; 45:10306-10320. [PMID: 28973472 PMCID: PMC5737660 DOI: 10.1093/nar/gkx700] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2017] [Accepted: 07/29/2017] [Indexed: 12/23/2022] Open
Abstract
Contact-dependent growth inhibition (CDI) is a mechanism of inter-cellular competition in which Gram-negative bacteria exchange polymorphic toxins using type V secretion systems. Here, we present structures of the CDI toxin from Escherichia coli NC101 in ternary complex with its cognate immunity protein and elongation factor Tu (EF-Tu). The toxin binds exclusively to domain 2 of EF-Tu, partially overlapping the site that interacts with the 3'-end of aminoacyl-tRNA (aa-tRNA). The toxin exerts a unique ribonuclease activity that cleaves the single-stranded 3'-end from tRNAs that contain guanine discriminator nucleotides. EF-Tu is required to support this tRNase activity in vitro, suggesting the toxin specifically cleaves substrate in the context of GTP·EF-Tu·aa-tRNA complexes. However, superimposition of the toxin domain onto previously solved GTP·EF-Tu·aa-tRNA structures reveals potential steric clashes with both aa-tRNA and the switch I region of EF-Tu. Further, the toxin induces conformational changes in EF-Tu, displacing a β-hairpin loop that forms a critical salt-bridge contact with the 3'-terminal adenylate of aa-tRNA. Together, these observations suggest that the toxin remodels GTP·EF-Tu·aa-tRNA complexes to free the 3'-end of aa-tRNA for entry into the nuclease active site.
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Affiliation(s)
- Karolina Michalska
- Midwest Center for Structural Genomics, Biosciences Division, Argonne National Laboratory, Argonne, IL 60439, USA.,Structural Biology Center, Biosciences Division, Argonne National Laboratory, Argonne, IL 60439, USA
| | - Grant C Gucinski
- Biomolecular Science and Engineering Program, University of California, Santa Barbara, CA 93106-9625, USA
| | - Fernando Garza-Sánchez
- Department of Molecular, Cellular and Developmental Biology, University of California, Santa Barbara, CA 93106-9625, USA
| | - Parker M Johnson
- Department of Molecular Biology and Biochemistry, University of California, Irvine, CA 92697, USA
| | - Lucy M Stols
- Midwest Center for Structural Genomics, Biosciences Division, Argonne National Laboratory, Argonne, IL 60439, USA
| | - William H Eschenfeldt
- Midwest Center for Structural Genomics, Biosciences Division, Argonne National Laboratory, Argonne, IL 60439, USA
| | - Gyorgy Babnigg
- Midwest Center for Structural Genomics, Biosciences Division, Argonne National Laboratory, Argonne, IL 60439, USA
| | - David A Low
- Biomolecular Science and Engineering Program, University of California, Santa Barbara, CA 93106-9625, USA.,Department of Molecular, Cellular and Developmental Biology, University of California, Santa Barbara, CA 93106-9625, USA
| | - Celia W Goulding
- Department of Molecular Biology and Biochemistry, University of California, Irvine, CA 92697, USA.,Department of Pharmaceutical Sciences, University of California, Irvine, CA 92697, USA
| | - Andrzej Joachimiak
- Midwest Center for Structural Genomics, Biosciences Division, Argonne National Laboratory, Argonne, IL 60439, USA.,Structural Biology Center, Biosciences Division, Argonne National Laboratory, Argonne, IL 60439, USA.,Department of Biochemistry and Molecular Biology, University of Chicago, Chicago, IL 60637, USA
| | - Christopher S Hayes
- Biomolecular Science and Engineering Program, University of California, Santa Barbara, CA 93106-9625, USA.,Department of Molecular, Cellular and Developmental Biology, University of California, Santa Barbara, CA 93106-9625, USA
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10
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Jennings MD, Kershaw CJ, Adomavicius T, Pavitt GD. Fail-safe control of translation initiation by dissociation of eIF2α phosphorylated ternary complexes. eLife 2017; 6:e24542. [PMID: 28315520 PMCID: PMC5404910 DOI: 10.7554/elife.24542] [Citation(s) in RCA: 44] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2016] [Accepted: 03/16/2017] [Indexed: 01/21/2023] Open
Abstract
Phosphorylation of eIF2α controls translation initiation by restricting the levels of active eIF2-GTP/Met-tRNAi ternary complexes (TC). This modulates the expression of all eukaryotic mRNAs and contributes to the cellular integrated stress response. Key to controlling the activity of eIF2 are translation factors eIF2B and eIF5, thought to primarily function with eIF2-GDP and TC respectively. Using a steady-state kinetics approach with purified proteins we demonstrate that eIF2B binds to eIF2 with equal affinity irrespective of the presence or absence of competing guanine nucleotides. We show that eIF2B can compete with Met-tRNAi for eIF2-GTP and can destabilize TC. When TC is formed with unphosphorylated eIF2, eIF5 can out-compete eIF2B to stabilize TC/eIF5 complexes. However when TC/eIF5 is formed with phosphorylated eIF2, eIF2B outcompetes eIF5 and destabilizes TC. These data uncover competition between eIF2B and eIF5 for TC and identify that phosphorylated eIF2-GTP translation initiation intermediate complexes can be inhibited by eIF2B.
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Affiliation(s)
- Martin D Jennings
- Division of Molecular and Cellular Function, Faculty of Biology Medicine and Health, The University of Manchester, Manchester, United Kingdom
- Manchester Academic Health Science Centre, The University of Manchester, Manchester, United Kingdom
| | - Christopher J Kershaw
- Division of Molecular and Cellular Function, Faculty of Biology Medicine and Health, The University of Manchester, Manchester, United Kingdom
- Manchester Academic Health Science Centre, The University of Manchester, Manchester, United Kingdom
| | - Tomas Adomavicius
- Division of Molecular and Cellular Function, Faculty of Biology Medicine and Health, The University of Manchester, Manchester, United Kingdom
- Manchester Academic Health Science Centre, The University of Manchester, Manchester, United Kingdom
| | - Graham D Pavitt
- Division of Molecular and Cellular Function, Faculty of Biology Medicine and Health, The University of Manchester, Manchester, United Kingdom
- Manchester Academic Health Science Centre, The University of Manchester, Manchester, United Kingdom
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11
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Activation of contact-dependent antibacterial tRNase toxins by translation elongation factors. Proc Natl Acad Sci U S A 2017; 114:E1951-E1957. [PMID: 28223500 DOI: 10.1073/pnas.1619273114] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Contact-dependent growth inhibition (CDI) is a mechanism by which bacteria exchange toxins via direct cell-to-cell contact. CDI systems are distributed widely among Gram-negative pathogens and are thought to mediate interstrain competition. Here, we describe tsf mutations that alter the coiled-coil domain of elongation factor Ts (EF-Ts) and confer resistance to the CdiA-CTEC869 tRNase toxin from enterohemorrhagic Escherichia coli EC869. Although EF-Ts is required for toxicity in vivo, our results indicate that it is dispensable for tRNase activity in vitro. We find that CdiA-CTEC869 binds to elongation factor Tu (EF-Tu) with high affinity and this interaction is critical for nuclease activity. Moreover, in vitro tRNase activity is GTP-dependent, suggesting that CdiA-CTEC869 only cleaves tRNA in the context of translationally active GTP·EF-Tu·tRNA ternary complexes. We propose that EF-Ts promotes the formation of GTP·EF-Tu·tRNA ternary complexes, thereby accelerating substrate turnover for rapid depletion of target-cell tRNA.
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12
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Qian H, Zhu K, Lu H, Lavoie M, Chen S, Zhou Z, Deng Z, Chen J, Fu Z. Contrasting silver nanoparticle toxicity and detoxification strategies in Microcystis aeruginosa and Chlorella vulgaris: New insights from proteomic and physiological analyses. THE SCIENCE OF THE TOTAL ENVIRONMENT 2016; 572:1213-1221. [PMID: 27522289 DOI: 10.1016/j.scitotenv.2016.08.039] [Citation(s) in RCA: 77] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/21/2016] [Revised: 08/03/2016] [Accepted: 08/05/2016] [Indexed: 06/06/2023]
Abstract
Several studies have shown that AgNPs can be toxic to phytoplankton, but the underlying cellular mechanisms still remain largely unknown. Here we studied the toxicity and detoxification of AgNPs (and ionic silver released by the AgNPs) in a prokaryotic (Microcystis aeruginosa) and a eukaryotic (Chlorella vulgaris) freshwater phytoplankton species using a combination of proteomic, gene transcription, and physiological analyses. We show that AgNPs were more toxic to the growth, photosynthesis, antioxidant systems, and carbohydrate metabolism of M. aeruginosa than of C. vulgaris. C. vulgaris could detoxify efficiently AgNPs-induced ROS species via induction of antioxidant enzymes (superoxide dismutase or SOD, peroxidase or POD, catalase or CAT, and glutamine synthetase), allowing photosynthesis to continue unabated at growth-inhibitory AgNPs concentration. By contrast, the transcription and expression of SOD and POD in M. aeruginosa was inhibited by the same AgNPs exposure. The present study shed new lights on the AgNPs toxicity mechanisms and detoxification strategies in two freshwater algae of contrasting AgNPs sensitivity.
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Affiliation(s)
- Haifeng Qian
- College of Environment, Zhejiang University of Technology, Hangzhou 310032, PR China
| | - Kun Zhu
- College of Biotechnology and Bioengineering, Zhejiang University of Technology, Hangzhou 310032, PR China
| | - Haiping Lu
- College of Agriculture and Biotechnology, Zhejiang University, Hangzhou 310058, PR China
| | - Michel Lavoie
- Quebec-Ocean and Takuvik Joint International Research Unit, Université Laval, Québec, Canada
| | - Si Chen
- Department of Food Science and Technology, Zhejiang University of Technology, Hangzhou 310032, PR China
| | - Zhongjing Zhou
- State Key Laboratory Breeding Base for Zhejiang Sustainable Pest and Disease Control, Institute of Virology and Biotechnology, Zhejiang Academy of Agricultural Sciences, Hangzhou 310021, PR China
| | - Zhiping Deng
- State Key Laboratory Breeding Base for Zhejiang Sustainable Pest and Disease Control, Institute of Virology and Biotechnology, Zhejiang Academy of Agricultural Sciences, Hangzhou 310021, PR China
| | - Jun Chen
- College of Environment, Zhejiang University of Technology, Hangzhou 310032, PR China
| | - Zhengwei Fu
- College of Biotechnology and Bioengineering, Zhejiang University of Technology, Hangzhou 310032, PR China.
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Ferguson A, Wang L, Altman RB, Terry DS, Juette MF, Burnett BJ, Alejo JL, Dass RA, Parks MM, Vincent CT, Blanchard SC. Functional Dynamics within the Human Ribosome Regulate the Rate of Active Protein Synthesis. Mol Cell 2015; 60:475-86. [PMID: 26593721 PMCID: PMC4660248 DOI: 10.1016/j.molcel.2015.09.013] [Citation(s) in RCA: 49] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2015] [Revised: 07/24/2015] [Accepted: 09/16/2015] [Indexed: 01/09/2023]
Abstract
The regulation of protein synthesis contributes to gene expression in both normal physiology and disease, yet kinetic investigations of the human translation mechanism are currently lacking. Using single-molecule fluorescence imaging methods, we have quantified the nature and timing of structural processes in human ribosomes during single-turnover and processive translation reactions. These measurements reveal that functional complexes exhibit dynamic behaviors and thermodynamic stabilities distinct from those observed for bacterial systems. Structurally defined sub-states of pre- and post-translocation complexes were sensitive to specific inhibitors of the eukaryotic ribosome, demonstrating the utility of this platform to probe drug mechanism. The application of three-color single-molecule fluorescence resonance energy transfer (smFRET) methods further revealed a long-distance allosteric coupling between distal tRNA binding sites within ribosomes bearing three tRNAs, which contributed to the rate of processive translation.
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Affiliation(s)
- Angelica Ferguson
- Department of Physiology and Biophysics, Weill Cornell Medical College, New York, NY 10065, USA; Tri-Institutional Training Program in Chemical Biology, Weill Cornell Medical College, Rockefeller University, Memorial Sloan-Kettering Cancer Center, New York, NY 10065, USA
| | - Leyi Wang
- Department of Physiology and Biophysics, Weill Cornell Medical College, New York, NY 10065, USA
| | - Roger B Altman
- Department of Physiology and Biophysics, Weill Cornell Medical College, New York, NY 10065, USA
| | - Daniel S Terry
- Department of Physiology and Biophysics, Weill Cornell Medical College, New York, NY 10065, USA
| | - Manuel F Juette
- Department of Physiology and Biophysics, Weill Cornell Medical College, New York, NY 10065, USA
| | - Benjamin J Burnett
- Department of Physiology and Biophysics, Weill Cornell Medical College, New York, NY 10065, USA
| | - Jose L Alejo
- Department of Physiology and Biophysics, Weill Cornell Medical College, New York, NY 10065, USA
| | - Randall A Dass
- Department of Physiology and Biophysics, Weill Cornell Medical College, New York, NY 10065, USA
| | - Matthew M Parks
- Department of Physiology and Biophysics, Weill Cornell Medical College, New York, NY 10065, USA
| | - C Theresa Vincent
- Department of Physiology and Biophysics, Weill Cornell Medical College, New York, NY 10065, USA; Department of Pharmacology and Physiology, Karolinska Institute, 171 77 Stockholm, Sweden
| | - Scott C Blanchard
- Department of Physiology and Biophysics, Weill Cornell Medical College, New York, NY 10065, USA; Tri-Institutional Training Program in Chemical Biology, Weill Cornell Medical College, Rockefeller University, Memorial Sloan-Kettering Cancer Center, New York, NY 10065, USA.
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14
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Thirup SS, Van LB, Nielsen TK, Knudsen CR. Structural outline of the detailed mechanism for elongation factor Ts-mediated guanine nucleotide exchange on elongation factor Tu. J Struct Biol 2015; 191:10-21. [PMID: 26073967 DOI: 10.1016/j.jsb.2015.06.011] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2015] [Revised: 06/05/2015] [Accepted: 06/11/2015] [Indexed: 11/26/2022]
Abstract
Translation elongation factor EF-Tu belongs to the superfamily of guanine-nucleotide binding proteins, which play key cellular roles as regulatory switches. All G-proteins require activation via exchange of GDP for GTP to carry out their respective tasks. Often, guanine-nucleotide exchange factors are essential to this process. During translation, EF-Tu:GTP transports aminoacylated tRNA to the ribosome. GTP is hydrolyzed during this process, and subsequent reactivation of EF-Tu is catalyzed by EF-Ts. The reaction path of guanine-nucleotide exchange is structurally poorly defined for EF-Tu and EF-Ts. We have determined the crystal structures of the following reaction intermediates: two structures of EF-Tu:GDP:EF-Ts (2.2 and 1.8Å resolution), EF-Tu:PO4:EF-Ts (1.9Å resolution), EF-Tu:GDPNP:EF-Ts (2.2Å resolution) and EF-Tu:GDPNP:pulvomycin:Mg(2+):EF-Ts (3.5Å resolution). These structures provide snapshots throughout the entire exchange reaction and suggest a mechanism for the release of EF-Tu in its GTP conformation. An inferred sequence of events during the exchange reaction is presented.
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Affiliation(s)
- Søren S Thirup
- Aarhus University, Department of Molecular Biology and Genetics, Center for Structural Biology, DK-8000 Aarhus C, Denmark.
| | - Lan Bich Van
- Aarhus University, Department of Molecular Biology and Genetics, Center for Structural Biology, DK-8000 Aarhus C, Denmark
| | - Tine K Nielsen
- Aarhus University, Department of Molecular Biology and Genetics, Center for Structural Biology, DK-8000 Aarhus C, Denmark
| | - Charlotte R Knudsen
- Aarhus University, Department of Molecular Biology and Genetics, Center for Structural Biology, DK-8000 Aarhus C, Denmark
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15
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Behrmann E, Loerke J, Budkevich TV, Yamamoto K, Schmidt A, Penczek PA, Vos MR, Bürger J, Mielke T, Scheerer P, Spahn CMT. Structural snapshots of actively translating human ribosomes. Cell 2015; 161:845-57. [PMID: 25957688 PMCID: PMC4432480 DOI: 10.1016/j.cell.2015.03.052] [Citation(s) in RCA: 136] [Impact Index Per Article: 15.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2014] [Revised: 01/05/2015] [Accepted: 02/27/2015] [Indexed: 10/23/2022]
Abstract
Macromolecular machines, such as the ribosome, undergo large-scale conformational changes during their functional cycles. Although their mode of action is often compared to that of mechanical machines, a crucial difference is that, at the molecular dimension, thermodynamic effects dominate functional cycles, with proteins fluctuating stochastically between functional states defined by energetic minima on an energy landscape. Here, we have used cryo-electron microscopy to image ex-vivo-derived human polysomes as a source of actively translating ribosomes. Multiparticle refinement and 3D variability analysis allowed us to visualize a variety of native translation intermediates. Significantly populated states include not only elongation cycle intermediates in pre- and post-translocational states, but also eEF1A-containing decoding and termination/recycling complexes. Focusing on the post-translocational state, we extended this assessment to the single-residue level, uncovering striking details of ribosome-ligand interactions and identifying both static and functionally important dynamic elements.
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Affiliation(s)
- Elmar Behrmann
- Institut für Medizinische Physik und Biophysik, Charité-Universitätsmedizin Berlin, Charitéplatz 1, 10117 Berlin, Germany
| | - Justus Loerke
- Institut für Medizinische Physik und Biophysik, Charité-Universitätsmedizin Berlin, Charitéplatz 1, 10117 Berlin, Germany
| | - Tatyana V Budkevich
- Institut für Medizinische Physik und Biophysik, Charité-Universitätsmedizin Berlin, Charitéplatz 1, 10117 Berlin, Germany
| | - Kaori Yamamoto
- Institut für Medizinische Physik und Biophysik, Charité-Universitätsmedizin Berlin, Charitéplatz 1, 10117 Berlin, Germany
| | - Andrea Schmidt
- Institut für Medizinische Physik und Biophysik, Charité-Universitätsmedizin Berlin, Charitéplatz 1, 10117 Berlin, Germany; Institut für Medizinische Physik und Biophysik, AG Protein X-Ray Crystallography, Charité-Universitätsmedizin Berlin, Charitéplatz 1, 10117 Berlin, Germany
| | - Pawel A Penczek
- Department of Biochemistry and Molecular Biology, The University of Texas Medical School, 6431 Fannin MSB 6.220, Houston, TX 77054, USA
| | - Matthijn R Vos
- FEI Company, Nanoport Europe, Achtseweg Noord 5, 5651 GG Eindhoven, the Netherlands
| | - Jörg Bürger
- Institut für Medizinische Physik und Biophysik, Charité-Universitätsmedizin Berlin, Charitéplatz 1, 10117 Berlin, Germany
| | - Thorsten Mielke
- Institut für Medizinische Physik und Biophysik, Charité-Universitätsmedizin Berlin, Charitéplatz 1, 10117 Berlin, Germany; Max-Planck Institut für Molekulare Genetik, Ihnestraße 63-73, 14195 Berlin, Germany
| | - Patrick Scheerer
- Institut für Medizinische Physik und Biophysik, Charité-Universitätsmedizin Berlin, Charitéplatz 1, 10117 Berlin, Germany; Institut für Medizinische Physik und Biophysik, AG Protein X-Ray Crystallography, Charité-Universitätsmedizin Berlin, Charitéplatz 1, 10117 Berlin, Germany
| | - Christian M T Spahn
- Institut für Medizinische Physik und Biophysik, Charité-Universitätsmedizin Berlin, Charitéplatz 1, 10117 Berlin, Germany.
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