101
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Bastet A, Lederer B, Giovinazzo N, Arnoux X, German‐Retana S, Reinbold C, Brault V, Garcia D, Djennane S, Gersch S, Lemaire O, Robaglia C, Gallois J. Trans-species synthetic gene design allows resistance pyramiding and broad-spectrum engineering of virus resistance in plants. PLANT BIOTECHNOLOGY JOURNAL 2018; 16:1569-1581. [PMID: 29504210 PMCID: PMC6097130 DOI: 10.1111/pbi.12896] [Citation(s) in RCA: 45] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/30/2017] [Revised: 01/10/2018] [Accepted: 01/28/2018] [Indexed: 05/19/2023]
Abstract
To infect plants, viruses rely heavily on their host's machinery. Plant genetic resistances based on host factor modifications can be found among existing natural variability and are widely used for some but not all crops. While biotechnology can supply for the lack of natural resistance alleles, new strategies need to be developed to increase resistance spectra and durability without impairing plant development. Here, we assess how the targeted allele modification of the Arabidopsis thaliana translation initiation factor eIF4E1 can lead to broad and efficient resistance to the major group of potyviruses. A synthetic Arabidopsis thaliana eIF4E1 allele was designed by introducing multiple amino acid changes associated with resistance to potyvirus in naturally occurring Pisum sativum alleles. This new allele encodes a functional protein while maintaining plant resistance to a potyvirus isolate that usually hijacks eIF4E1. Due to its biological functionality, this synthetic allele allows, at no developmental cost, the pyramiding of resistances to potyviruses that selectively use the two major translation initiation factors, eIF4E1 or its isoform eIFiso4E. Moreover, this combination extends the resistance spectrum to potyvirus isolates for which no efficient resistance has so far been found, including resistance-breaking isolates and an unrelated virus belonging to the Luteoviridae family. This study is a proof-of-concept for the efficiency of gene engineering combined with knowledge of natural variation to generate trans-species virus resistance at no developmental cost to the plant. This has implications for breeding of crops with broad-spectrum and high durability resistance using recent genome editing techniques.
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Affiliation(s)
- Anna Bastet
- GAFLINRAMontfavetFrance
- Aix Marseille UniversityUMR 7265 Biologie Végétale et Microbiologie EnvironnementalesLaboratoire de Génétique et Biophysique des PlantesMarseilleFrance
- CNRSUMR 7265 Biologie Végétale et Microbiologie EnvironnementalesMarseilleFrance
- CEABioscience and Biotechnology Institute of Aix‐MarseilleMarseilleFrance
| | | | | | - Xavier Arnoux
- UMR 1332 Biologie du Fruit et PathologieINRAUniv. BordeauxVillenave d'OrnonFrance
| | - Sylvie German‐Retana
- UMR 1332 Biologie du Fruit et PathologieINRAUniv. BordeauxVillenave d'OrnonFrance
| | - Catherine Reinbold
- Université de StrasbourgINRAUMR‐A 1131Santé de la Vigne et Qualité du VinColmarFrance
| | - Véronique Brault
- Université de StrasbourgINRAUMR‐A 1131Santé de la Vigne et Qualité du VinColmarFrance
| | - Damien Garcia
- Centre National de la Recherche ScientifiqueInstitut de Biologie Moléculaire des Plantes (IBMP)UPR 2357StrasbourgFrance
| | - Samia Djennane
- Université de StrasbourgINRAUMR‐A 1131Santé de la Vigne et Qualité du VinColmarFrance
| | - Sophie Gersch
- Université de StrasbourgINRAUMR‐A 1131Santé de la Vigne et Qualité du VinColmarFrance
| | - Olivier Lemaire
- Université de StrasbourgINRAUMR‐A 1131Santé de la Vigne et Qualité du VinColmarFrance
| | - Christophe Robaglia
- Aix Marseille UniversityUMR 7265 Biologie Végétale et Microbiologie EnvironnementalesLaboratoire de Génétique et Biophysique des PlantesMarseilleFrance
- CNRSUMR 7265 Biologie Végétale et Microbiologie EnvironnementalesMarseilleFrance
- CEABioscience and Biotechnology Institute of Aix‐MarseilleMarseilleFrance
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102
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Hashem Y, Frank J. The Jigsaw Puzzle of mRNA Translation Initiation in Eukaryotes: A Decade of Structures Unraveling the Mechanics of the Process. Annu Rev Biophys 2018; 47:125-151. [PMID: 29494255 DOI: 10.1146/annurev-biophys-070816-034034] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
Translation initiation in eukaryotes is a highly regulated and rate-limiting process. It results in the assembly and disassembly of numerous transient and intermediate complexes involving over a dozen eukaryotic initiation factors (eIFs). This process culminates in the accommodation of a start codon marking the beginning of an open reading frame at the appropriate ribosomal site. Although this process has been extensively studied by hundreds of groups for nearly half a century, it has been only recently, especially during the last decade, that we have gained deeper insight into the mechanics of the eukaryotic translation initiation process. This advance in knowledge is due in part to the contributions of structural biology, which have shed light on the molecular mechanics underlying the different functions of various eukaryotic initiation factors. In this review, we focus exclusively on the contribution of structural biology to the understanding of the eukaryotic initiation process, a long-standing jigsaw puzzle that is just starting to yield the bigger picture.
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Affiliation(s)
- Yaser Hashem
- INSERM U1212, Institut Européen de Chimie et Biologie, Université de Bordeaux, Pessac 33607, France;
| | - Joachim Frank
- Department of Biological Sciences, Columbia University, New York, NY 10032, USA;
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103
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Kalous J, Tetkova A, Kubelka M, Susor A. Importance of ERK1/2 in Regulation of Protein Translation during Oocyte Meiosis. Int J Mol Sci 2018; 19:ijms19030698. [PMID: 29494492 PMCID: PMC5877559 DOI: 10.3390/ijms19030698] [Citation(s) in RCA: 34] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2018] [Revised: 02/23/2018] [Accepted: 02/26/2018] [Indexed: 02/07/2023] Open
Abstract
Although the involvement of the extracellular signal-regulated kinases 1 and 2 (ERK1/2) pathway in the regulation of cytostatic factor (CSF) activity; as well as in microtubules organization during meiotic maturation of oocytes; has already been described in detail; rather less attention has been paid to the role of ERK1/2 in the regulation of mRNA translation. However; important data on the role of ERK1/2 in translation during oocyte meiosis have been documented. This review focuses on recent findings regarding the regulation of translation and the role of ERK1/2 in this process in the meiotic cycle of mammalian oocytes. The specific role of ERK1/2 in the regulation of mammalian target of rapamycin (mTOR); eukaryotic translation initiation factor 4E (eIF4E) and cytoplasmic polyadenylation element binding protein 1 (CPEB1) activity is addressed along with additional focus on the other key players involved in protein translation.
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Affiliation(s)
- Jaroslav Kalous
- Institute of Animal Physiology and Genetics, Academy of Sciences of the Czech Republic, Rumburska 89, 27721 Libechov, Czech Republic.
| | - Anna Tetkova
- Institute of Animal Physiology and Genetics, Academy of Sciences of the Czech Republic, Rumburska 89, 27721 Libechov, Czech Republic.
- Department of Cell Biology, Faculty of Science, Charles University in Prague, Albertov 6, 12843 Prague 2, Czech Republic.
| | - Michal Kubelka
- Institute of Animal Physiology and Genetics, Academy of Sciences of the Czech Republic, Rumburska 89, 27721 Libechov, Czech Republic.
| | - Andrej Susor
- Institute of Animal Physiology and Genetics, Academy of Sciences of the Czech Republic, Rumburska 89, 27721 Libechov, Czech Republic.
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104
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Piserà A, Campo A, Campo S. Structure and functions of the translation initiation factor eIF4E and its role in cancer development and treatment. J Genet Genomics 2018; 45:13-24. [DOI: 10.1016/j.jgg.2018.01.003] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2017] [Revised: 01/12/2018] [Accepted: 01/15/2018] [Indexed: 12/22/2022]
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105
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Muttach F, Muthmann N, Rentmeister A. Synthetic mRNA capping. Beilstein J Org Chem 2017; 13:2819-2832. [PMID: 30018667 PMCID: PMC5753152 DOI: 10.3762/bjoc.13.274] [Citation(s) in RCA: 60] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2017] [Accepted: 12/04/2017] [Indexed: 12/25/2022] Open
Abstract
Eukaryotic mRNA with its 5'-cap is of central importance for the cell. Many studies involving mRNA require reliable preparation and modification of 5'-capped RNAs. Depending on the length of the desired capped RNA, chemical or enzymatic preparation - or a combination of both - can be advantageous. We review state-of-the art methods and give directions for choosing the appropriate approach. We also discuss the preparation and properties of mRNAs with non-natural caps providing novel features such as improved stability or enhanced translational efficiency.
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Affiliation(s)
- Fabian Muttach
- University of Münster, Department of Chemistry, Institute of Biochemistry, Wilhelm-Klemm-Str. 2, 48149 Münster, Germany
| | - Nils Muthmann
- University of Münster, Department of Chemistry, Institute of Biochemistry, Wilhelm-Klemm-Str. 2, 48149 Münster, Germany
| | - Andrea Rentmeister
- University of Münster, Department of Chemistry, Institute of Biochemistry, Wilhelm-Klemm-Str. 2, 48149 Münster, Germany
- Cells-in-Motion Cluster of Excellence (EXC1003-CiM), University of Münster, Germany
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106
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Trotman JB, Giltmier AJ, Mukherjee C, Schoenberg DR. RNA guanine-7 methyltransferase catalyzes the methylation of cytoplasmically recapped RNAs. Nucleic Acids Res 2017; 45:10726-10739. [PMID: 28981715 PMCID: PMC5737702 DOI: 10.1093/nar/gkx801] [Citation(s) in RCA: 47] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2017] [Accepted: 08/30/2017] [Indexed: 12/31/2022] Open
Abstract
Cap homeostasis is a cyclical process of decapping and recapping that impacts a portion of the mRNA transcriptome. The metastable uncapped forms of recapping targets redistribute from polysomes to non-translating mRNPs, and recapping is all that is needed for their return to the translating pool. Previous work identified a cytoplasmic capping metabolon consisting of capping enzyme (CE) and a 5′-monophosphate kinase bound to adjacent domains of Nck1. The current study identifies the canonical cap methyltransferase (RNMT) as the enzyme responsible for guanine-N7 methylation of recapped mRNAs. RNMT binds directly to CE, and its presence in the cytoplasmic capping complex was demonstrated by pulldown assays, gel filtration and proximity-dependent biotinylation. The latter also identified the RNMT cofactor RAM, whose presence is required for cytoplasmic cap methyltransferase activity. These findings guided development of an inhibitor of cytoplasmic cap methylation whose action resulted in a selective decrease in levels of recapped mRNAs.
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Affiliation(s)
- Jackson B Trotman
- Center for RNA Biology, The Ohio State University, Columbus, OH 43210, USA.,Ohio State Biochemistry Program, The Ohio State University, Columbus, OH 43210, USA.,Department of Biological Chemistry and Pharmacology, The Ohio State University, Columbus, OH 43210, USA
| | - Andrew J Giltmier
- Center for RNA Biology, The Ohio State University, Columbus, OH 43210, USA.,Department of Biological Chemistry and Pharmacology, The Ohio State University, Columbus, OH 43210, USA
| | - Chandrama Mukherjee
- Center for RNA Biology, The Ohio State University, Columbus, OH 43210, USA.,Department of Biological Chemistry and Pharmacology, The Ohio State University, Columbus, OH 43210, USA
| | - Daniel R Schoenberg
- Center for RNA Biology, The Ohio State University, Columbus, OH 43210, USA.,Department of Biological Chemistry and Pharmacology, The Ohio State University, Columbus, OH 43210, USA
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107
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Interaction of 2A proteinase of human rhinovirus genetic group A with eIF4E is required for eIF4G cleavage during infection. Virology 2017; 511:123-134. [DOI: 10.1016/j.virol.2017.08.020] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2017] [Revised: 08/11/2017] [Accepted: 08/14/2017] [Indexed: 01/04/2023]
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108
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The Role of Cytoplasmic mRNA Cap-Binding Protein Complexes in Trypanosoma brucei and Other Trypanosomatids. Pathogens 2017; 6:pathogens6040055. [PMID: 29077018 PMCID: PMC5750579 DOI: 10.3390/pathogens6040055] [Citation(s) in RCA: 44] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2017] [Revised: 10/21/2017] [Accepted: 10/22/2017] [Indexed: 11/16/2022] Open
Abstract
Trypanosomatid protozoa are unusual eukaryotes that are well known for having unusual ways of controlling their gene expression. The lack of a refined mode of transcriptional control in these organisms is compensated by several post-transcriptional control mechanisms, such as control of mRNA turnover and selection of mRNA for translation, that may modulate protein synthesis in response to several environmental conditions found in different hosts. In other eukaryotes, selection of mRNA for translation is mediated by the complex eIF4F, a heterotrimeric protein complex composed by the subunits eIF4E, eIF4G, and eIF4A, where the eIF4E binds to the 5'-cap structure of mature mRNAs. In this review, we present and discuss the characteristics of six trypanosomatid eIF4E homologs and their associated proteins that form multiple eIF4F complexes. The existence of multiple eIF4F complexes in trypanosomatids evokes exquisite mechanisms for differential mRNA recognition for translation.
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109
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Khan MA, Goss DJ. Kinetic analyses of phosphorylated and non-phosphorylated eIFiso4E binding to mRNA cap analogues. Int J Biol Macromol 2017; 106:387-395. [PMID: 28797816 DOI: 10.1016/j.ijbiomac.2017.08.041] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2017] [Revised: 07/24/2017] [Accepted: 08/04/2017] [Indexed: 01/23/2023]
Abstract
Phosphorylation of eukaryotic initiation factors was previously shown to interact with m7G cap and play an important role in the regulation of translation initiation of protein synthesis. To gain further insight into the phosphorylation process of plant protein synthesis, the kinetics of phosphorylated wheat eIFiso4E binding to m7G cap analogues were examined. Phosphorylation of wheat eIFiso4E showed similar kinetic effects to human eIF4E binding to m7-G cap. Phosphorylation of eIFiso4E decreased the kinetic rate (2-fold) and increased the dissociation rate (2-fold) as compared to non-phosphorylated eIFiso4E binding to both mono- and di-nucleotide analogues at 22°C. Phosphorylated and non-phosphorylated eIFiso4E-m7G cap binding rates were found to be independent of concentration, suggesting conformational changes were rate limiting. Rate constant for phosphorylated and non-phosphorylated eIFiso4E binding to m7-G cap increased with temperature. Phosphorylation of eIFiso4E decreased (2-fold) the activation energy for both m7-G cap analogues binding as compared to non-phosphorylated eIFiso4E. The reduced energy barrier for the formation of eIFiso4E-m7-G cap complex suggests a more stable platform for further initiation complex formation and possible means of adapting variety of environmental conditions. Furthermore, the formation of phosphorylated eIFiso4E-cap complex may contribute to modulation of the initiation of protein synthesis in plants.
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Affiliation(s)
- Mateen A Khan
- Department of Chemistry and Biochemistry, Hunter College of the City University of New York, New York, NY 10065, USA; Department of Life Sciences, College of Science and General Studies, Alfaisal University, Riyadh 11533, KSA, Saudi Arabia.
| | - Dixie J Goss
- Department of Chemistry and Biochemistry, Hunter College of the City University of New York, New York, NY 10065, USA.
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110
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Shi S, Zhang X, Mandel MA, Zhang P, Zhang Y, Ferguson M, Amuge T, Rounsley S, Liu Z, Xiong Z. Variations of five eIF4E genes across cassava accessions exhibiting tolerant and susceptible responses to cassava brown streak disease. PLoS One 2017; 12:e0181998. [PMID: 28771520 PMCID: PMC5542559 DOI: 10.1371/journal.pone.0181998] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2017] [Accepted: 07/11/2017] [Indexed: 11/19/2022] Open
Abstract
Cassava (Manihot esculenta) is an important tropical subsistence crop that is severely affected by cassava brown streak disease (CBSD) in East Africa. The disease is caused by Cassava brown streak virus (CBSV) and Ugandan cassava brown streak virus (UCBSV). Both have a (+)-sense single-stranded RNA genome with a 5' covalently-linked viral protein, which functionally resembles the cap structure of mRNA, binds to eukaryotic translation initiation factor 4E (eIF4E) or its analogues, and then enable the translation of viral genomic RNA in host cells. To characterize cassava eIF4Es and their potential role in CBSD tolerance and susceptibility, we cloned five eIF4E transcripts from cassava (accession TMS60444). Sequence analysis indicated that the cassava eIF4E family of proteins consisted of one eIF4E, two eIF(iso)4E, and two divergent copies of novel cap-binding proteins (nCBPs). Our data demonstrated experimentally the coding of these five genes as annotated in the published cassava genome and provided additional evidence for refined annotations. Illumina resequencing data of the five eIF4E genes were analyzed from 14 cassava lines tolerant or susceptible to CBSD. Abundant single nucleotide polymorphisms (SNP) and biallelic variations were observed in the eIF4E genes; however, most of the SNPs were located in the introns and non-coding regions of the exons. Association studies of non-synonymous SNPs revealed no significant association between any SNP of the five eIF4E genes and the tolerance or susceptibility to CBSD. However, two SNPs in two genes were weakly associated with the CBSD responses but had no direct causal-effect relationship. SNPs in an intergenic region upstream of eIF4E_me showed a surprising strong association with CBSD responses. Digital expression profile analysis showed differential expression of different eIF4E genes but no significant difference in gene expression was found between susceptible and tolerant cassava accessions despite the association of the intergenic SNPs with CBSD responses.
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Affiliation(s)
- Shanshan Shi
- Institute of Tropical biology and biotechnology, Chinese Academy of Tropical Agricultural Sciences, Haikou, China
- School of Plant Sciences and BIO5 Institute, University of Arizona, Tucson, Arizona, United States of America
| | - Xiuchun Zhang
- Institute of Tropical biology and biotechnology, Chinese Academy of Tropical Agricultural Sciences, Haikou, China
| | - M. Alejandra Mandel
- School of Plant Sciences and BIO5 Institute, University of Arizona, Tucson, Arizona, United States of America
| | - Peng Zhang
- National Key Laboratory of Plant Molecular Genetics, CAS Center for Excellence in Molecular Plant Sciences, Institute of Plant Physiology and Ecology, Chinese Academy of Sciences, Shanghai, China
| | - Yuliang Zhang
- Institute of Tropical biology and biotechnology, Chinese Academy of Tropical Agricultural Sciences, Haikou, China
| | - Morag Ferguson
- International Institute of Tropical Agriculture (IITA), Nairobi, Kenya
| | - Teddy Amuge
- International Institute of Tropical Agriculture (IITA), Nairobi, Kenya
| | - Steve Rounsley
- Genus plc, DeForest, Wisconsin, United States of America
| | - Zhixin Liu
- Institute of Tropical biology and biotechnology, Chinese Academy of Tropical Agricultural Sciences, Haikou, China
- * E-mail: (ZX); (ZL)
| | - Zhongguo Xiong
- School of Plant Sciences and BIO5 Institute, University of Arizona, Tucson, Arizona, United States of America
- * E-mail: (ZX); (ZL)
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111
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Piecyk K, Krynska P, Kaluzna J, Jankowska-Anyszka M. Synthesis of the first double-functionalized dinucleotide mRNA cap analogue for its specific labeling. Tetrahedron Lett 2017. [DOI: 10.1016/j.tetlet.2017.06.060] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
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112
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Miras M, Truniger V, Querol‐Audi J, Aranda MA. Analysis of the interacting partners eIF4F and 3'-CITE required for Melon necrotic spot virus cap-independent translation. MOLECULAR PLANT PATHOLOGY 2017; 18:635-648. [PMID: 27145354 PMCID: PMC6638222 DOI: 10.1111/mpp.12422] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/15/2016] [Revised: 04/26/2016] [Accepted: 04/28/2016] [Indexed: 05/17/2023]
Abstract
We have shown previously that the translation of Melon necrotic spot virus (MNSV, family Tombusviridae, genus Carmovirus) RNAs is controlled by a 3'-cap-independent translation enhancer (CITE), which is genetically and functionally dependent on the eukaryotic translation initiation factor (eIF) 4E. Here, we describe structural and functional analyses of the MNSV-Mα5 3'-CITE and its translation initiation factor partner. We first mapped the minimal 3'-CITE (Ma5TE) to a 45-nucleotide sequence, which consists of a stem-loop structure with two internal loops, similar to other I-shaped 3'-CITEs. UV crosslinking, followed by gel retardation assays, indicated that Ma5TE interacts in vitro with the complex formed by eIF4E + eIF4G980-1159 (eIF4Fp20 ), but not with each subunit alone or with eIF4E + eIF4G1003-1092 , suggesting binding either through interaction with eIF4E following a conformational change induced by its binding to eIF4G980-1159 , or through a double interaction with eIF4E and eIF4G980-1159 . Critical residues for this interaction reside in an internal bulge of Ma5TE, so that their mutation abolished binding to eIF4E + eIF4G1003-1092 and cap-independent translation. We also developed an in vivo system to test the effect of mutations in eIF4E in Ma5TE-driven cap-independent translation, showing that conserved amino acids in a positively charged RNA-binding motif around amino acid position 228, implicated in eIF4E-eIF4G binding or belonging to the cap-recognition pocket, are essential for cap-independent translation controlled by Ma5TE, and thus for the multiplication of MNSV.
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Affiliation(s)
- Manuel Miras
- Centro de Edafología y Biología Aplicada del Segura (CEBAS) ‐ CSICApdo. correos 164, 30100 EspinardoMurciaSpain
| | - Verónica Truniger
- Centro de Edafología y Biología Aplicada del Segura (CEBAS) ‐ CSICApdo. correos 164, 30100 EspinardoMurciaSpain
| | - Jordi Querol‐Audi
- Molecular Biology Institute of Barcelona (IBMB‐CSIC)Parc Científic de Barcelona, Baldiri i Reixac 10Barcelona08028Spain
| | - Miguel A. Aranda
- Centro de Edafología y Biología Aplicada del Segura (CEBAS) ‐ CSICApdo. correos 164, 30100 EspinardoMurciaSpain
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113
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Min KW, Davila S, Zealy RW, Lloyd LT, Lee IY, Lee R, Roh KH, Jung A, Jemielity J, Choi EJ, Chang JH, Yoon JH. eIF4E phosphorylation by MST1 reduces translation of a subset of mRNAs, but increases lncRNA translation. BIOCHIMICA ET BIOPHYSICA ACTA-GENE REGULATORY MECHANISMS 2017; 1860:761-772. [PMID: 28487214 DOI: 10.1016/j.bbagrm.2017.05.002] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Received: 10/03/2016] [Revised: 05/03/2017] [Accepted: 05/05/2017] [Indexed: 10/19/2022]
Abstract
Post-transcriptional gene regulation is an important step in eukaryotic gene expression. The last step to govern production of nascent peptides is during the process of mRNA translation. mRNA translation is controlled by many translation initiation factors that are susceptible to post-translational modifications. Here we report that one of the translation initiation factors, eIF4E, is phosphorylated by Mammalian Ste20-like kinase (MST1). Upon phosphorylation, eIF4E weakly interacts with the 5' CAP to inhibit mRNA translation. Simultaneously, active polyribosome is more associated with long noncoding RNAs (lncRNAs). Moreover, the linc00689-derived micropeptide, STORM (Stress- and TNF-α-activated ORF Micropeptide), is triggered by TNF-α-induced and MST1-mediated eIF4E phosphorylation, which exhibits molecular mimicry of SRP19 and, thus, competes for 7SL RNA. Our findings have uncovered a novel function of MST1 in mRNA and lncRNA translation by direct phosphorylation of eIF4E. This novel signaling pathway will provide new platforms for regulation of mRNA translation via post-translational protein modification.
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Affiliation(s)
- Kyung-Won Min
- Department of Biochemistry and Molecular Biology, Medical University of South Carolina, Charleston, SC 29425, USA
| | - Sylvia Davila
- Department of Biochemistry and Molecular Biology, Medical University of South Carolina, Charleston, SC 29425, USA
| | - Richard W Zealy
- Department of Biochemistry and Molecular Biology, Medical University of South Carolina, Charleston, SC 29425, USA
| | - Lawson T Lloyd
- Department of Biochemistry and Molecular Biology, Medical University of South Carolina, Charleston, SC 29425, USA
| | - In Young Lee
- Laboratory of Cell Death and Human Diseases, Department of Life Sciences, School of Life Sciences and Biotechnology, Korea University, Seoul, Republic of Korea
| | - Rumi Lee
- Laboratory of Cell Death and Human Diseases, Department of Life Sciences, School of Life Sciences and Biotechnology, Korea University, Seoul, Republic of Korea
| | - Kyung Hye Roh
- Laboratory of Cell Death and Human Diseases, Department of Life Sciences, School of Life Sciences and Biotechnology, Korea University, Seoul, Republic of Korea
| | - Ahjin Jung
- Department of Biology Education, Kyungpook National University, Daegu 41566, Republic of Korea
| | - Jacek Jemielity
- Centre of New Technologies, University of Warsaw, S. Banacha 2c, 02-097 Warsaw, Poland
| | - Eui-Ju Choi
- Laboratory of Cell Death and Human Diseases, Department of Life Sciences, School of Life Sciences and Biotechnology, Korea University, Seoul, Republic of Korea
| | - Jeong Ho Chang
- Department of Biology Education, Kyungpook National University, Daegu 41566, Republic of Korea.
| | - Je-Hyun Yoon
- Department of Biochemistry and Molecular Biology, Medical University of South Carolina, Charleston, SC 29425, USA; Laboratory of Genetics, National Institute on Aging-Intramural Research Program, NIH, Baltimore, MD 21224, USA.
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114
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Li J, Wang W, He Y, Li Y, Yan EZ, Zhang K, Irvine DJ, Hammond PT. Structurally Programmed Assembly of Translation Initiation Nanoplex for Superior mRNA Delivery. ACS NANO 2017; 11:2531-2544. [PMID: 28157292 PMCID: PMC5629916 DOI: 10.1021/acsnano.6b08447] [Citation(s) in RCA: 65] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
Messenger RNA (mRNA) represents a promising class of nucleic-acid-based therapeutics. While numerous nanocarriers have been developed for mRNA delivery, the inherent labile nature of mRNA results in a very low transfection efficiency and poor expression of desired protein. Here we preassemble the mRNA translation initiation structure through an inherent molecular recognition between 7-methylguanosine (m7G)-capped mRNA and eukaryotic initiation factor 4E (eIF4E) protein to form ribonucleoproteins (RNPs), thereby mimicking the first step of protein synthesis inside cells. Subsequent electrostatic stabilization of RNPs with structurally tunable cationic carriers leads to nanosized complexes (nanoplexes), which elicit high levels of mRNA transfection in different cell types by enhancing intracellular mRNA stability and protein synthesis. By investigating a family of synthetic polypeptides bearing different side group arrangements of cationic charge, we find that the molecular structure modulates the nanoscale distance between the mRNA strand and the eIF4E protein inside the nanoplex, which directly impacts the enhancement of mRNA transfection. To demonstrate the biomedical potential of this approach, we use this approach to introduce mRNA/eIF4E nanoplexes to murine dendritic cells, resulting in increased activation of cytotoxic CD8 T cells ex vivo. More importantly, eIF4E enhances gene expression in lungs following a systemic delivery of luciferase mRNA/eIF4E in mice. Collectively, this bioinspired molecular assembly method could lead to a new paradigm of gene delivery.
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Affiliation(s)
- Jiahe Li
- Koch Institute for Integrative Cancer Research, Massachusetts Institute of Technology, Cambridge, MA 02139
- Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139
| | - Wade Wang
- Koch Institute for Integrative Cancer Research, Massachusetts Institute of Technology, Cambridge, MA 02139
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, MA 02139
| | - Yanpu He
- Koch Institute for Integrative Cancer Research, Massachusetts Institute of Technology, Cambridge, MA 02139
- Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139
| | - Yingzhong Li
- Koch Institute for Integrative Cancer Research, Massachusetts Institute of Technology, Cambridge, MA 02139
- Department of Biological Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139
| | - Emily Z. Yan
- Koch Institute for Integrative Cancer Research, Massachusetts Institute of Technology, Cambridge, MA 02139
- Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139
| | - Ketian Zhang
- Koch Institute for Integrative Cancer Research, Massachusetts Institute of Technology, Cambridge, MA 02139
- Department of Materials Science and Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139
| | - Darrell J. Irvine
- Koch Institute for Integrative Cancer Research, Massachusetts Institute of Technology, Cambridge, MA 02139
- Department of Biological Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139
- Department of Materials Science and Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139
- Howard Hughes Medical Institute, Chevy Chase, MD 20815
| | - Paula T. Hammond
- Koch Institute for Integrative Cancer Research, Massachusetts Institute of Technology, Cambridge, MA 02139
- Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139
- Correspondence: David H. Koch Professor in Engineering, Bayer Chair Professor of Chemical Engineering, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA 02139, United States.
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115
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Abbas YM, Laudenbach BT, Martínez-Montero S, Cencic R, Habjan M, Pichlmair A, Damha MJ, Pelletier J, Nagar B. Structure of human IFIT1 with capped RNA reveals adaptable mRNA binding and mechanisms for sensing N1 and N2 ribose 2'-O methylations. Proc Natl Acad Sci U S A 2017; 114:E2106-E2115. [PMID: 28251928 PMCID: PMC5358387 DOI: 10.1073/pnas.1612444114] [Citation(s) in RCA: 71] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
IFIT1 (IFN-induced protein with tetratricopeptide repeats-1) is an effector of the host innate immune antiviral response that prevents propagation of virus infection by selectively inhibiting translation of viral mRNA. It relies on its ability to compete with the translation initiation factor eIF4F to specifically recognize foreign capped mRNAs, while remaining inactive against host mRNAs marked by ribose 2'-O methylation at the first cap-proximal nucleotide (N1). We report here several crystal structures of RNA-bound human IFIT1, including a 1.6-Å complex with capped RNA. IFIT1 forms a water-filled, positively charged RNA-binding tunnel with a separate hydrophobic extension that unexpectedly engages the cap in multiple conformations (syn and anti) giving rise to a relatively plastic and nonspecific mode of binding, in stark contrast to eIF4E. Cap-proximal nucleotides encircled by the tunnel provide affinity to compete with eIF4F while allowing IFIT1 to select against N1 methylated mRNA. Gel-shift binding assays confirm that N1 methylation interferes with IFIT1 binding, but in an RNA-dependent manner, whereas translation assays reveal that N1 methylation alone is not sufficient to prevent mRNA recognition at high IFIT1 concentrations. Structural and functional analysis show that 2'-O methylation at N2, another abundant mRNA modification, is also detrimental for RNA binding, thus revealing a potentially synergistic role for it in self- versus nonself-mRNA discernment. Finally, structure-guided mutational analysis confirms the importance of RNA binding for IFIT1 restriction of a human coronavirus mutant lacking viral N1 methylation. Our structural and biochemical analysis sheds new light on the molecular basis for IFIT1 translational inhibition of capped viral RNA.
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Affiliation(s)
- Yazan M Abbas
- Department of Biochemistry and Groupe de Recherche Axe sur la Structure des Proteines, McGill University, Montreal, QC, Canada H3G 0B1
| | | | | | - Regina Cencic
- Department of Biochemistry, McGill University, Montreal, QC, Canada H3G 1Y6
| | - Matthias Habjan
- Innate Immunity Laboratory, Max-Planck Institute of Biochemistry, 82152 Martinsried/Munich, Germany
| | - Andreas Pichlmair
- Innate Immunity Laboratory, Max-Planck Institute of Biochemistry, 82152 Martinsried/Munich, Germany
| | - Masad J Damha
- Department of Chemistry, McGill University, Montreal, QC, Canada H3A 0B8
| | - Jerry Pelletier
- Department of Biochemistry, McGill University, Montreal, QC, Canada H3G 1Y6
- The Rosalind and Morris Goodman Cancer Research Center, Montreal, QC, Canada H3A 1A3
- Department of Oncology, McGill University, Montreal, QC, Canada H3G 1Y6
| | - Bhushan Nagar
- Department of Biochemistry and Groupe de Recherche Axe sur la Structure des Proteines, McGill University, Montreal, QC, Canada H3G 0B1;
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116
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Teng B, Ma P, Yu C, Zhang X, Feng Q, Wen L, Li C, Cheng Z, Jin D, Lin J. Upconversion nanoparticles loaded with eIF4E siRNA and platinum(iv) prodrug to sensitize platinum based chemotherapy for laryngeal cancer and bioimaging. J Mater Chem B 2017; 5:307-317. [PMID: 32263549 DOI: 10.1039/c6tb02360f] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Eukaryotic translation initiation factor (eIF) 4E is a valuable marker in cancer prognostics in many human cancers.
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117
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Bohnuud T, Jones G, Schueler-Furman O, Kozakov D. Detection of Peptide-Binding Sites on Protein Surfaces Using the Peptimap Server. Methods Mol Biol 2017; 1561:11-20. [PMID: 28236230 DOI: 10.1007/978-1-4939-6798-8_2] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Peptide-mediated interactions are of primordial importance to the cell, and the structure of such interaction provides an important starting point for their further characterization. In many cases, the structure of the peptide-protein complex has not been solved by experiment, and modeling tools need to be applied to generate structural models of the interaction. PeptiMap is a protocol that identifies the peptide-binding site when only the structure of the receptor is known, but no information about where the peptide binds is available. This is achieved by mapping the surface for solvents to identify ligand-binding sites, similar in approach to ANCHORMAP in which amino acids are mapped. Peptimap is a free open access web-based server. It can be accessed at http://peptimap.cluspro.org .
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Affiliation(s)
- Tanggis Bohnuud
- Department of Biomedical Engineering, Boston University, 44 Cummington St., Boston, MA, 02215, USA
| | - George Jones
- Department of Applied Mathematics and Statistics, Stony Brook University, New York, NY, USA
| | - Ora Schueler-Furman
- Department of Microbiology and Molecular Genetics, Institute for Medical Research Israel-Canada, Hadassah Medical School, The Hebrew University of Jerusalem, Jerusalem, Israel.
| | - Dima Kozakov
- Department of Biomedical Engineering, Boston University, 44 Cummington St., Boston, MA, 02215, USA.
- Department of Applied Mathematics and Statistics, Stony Brook University, New York, NY, USA.
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118
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Spell SR, Mangrum JB, Peterson EJ, Fabris D, Ptak R, Farrell NP. Au(iii) compounds as HIV nucleocapsid protein (NCp7)-nucleic acid antagonists. Chem Commun (Camb) 2016; 53:91-94. [PMID: 27858001 PMCID: PMC7086404 DOI: 10.1039/c6cc07970a] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The HIV nucleocapsid NCp7-SL2 RNA interaction is interrupted in the presence of a formally substitution-inert gold(dien)-nucleobase/N-heterocycle AuN4 compound where the N-heterocycle serves the dual purposes of a template for "non-covalent" molecular recognition of the essential tryptophan of the protein, mimicking the natural reaction and subsequent "fixation" by Au-Cys bond formation providing a chemotype for a new distinct class of nucleocapsid-nucleic acid antagonist.
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Affiliation(s)
- Sarah R Spell
- Department of Chemistry, Virginia Commonwealth University, Richmond, VA 23284-2006, USA.
| | - John B Mangrum
- The RNA Institute, University at Albany, State University of New York, 1400 Washington Avenue, Albany, NY 12222, USA
| | - Erica J Peterson
- Department of Chemistry, Virginia Commonwealth University, Richmond, VA 23284-2006, USA.
| | - Daniele Fabris
- The RNA Institute, University at Albany, State University of New York, 1400 Washington Avenue, Albany, NY 12222, USA
| | - Roger Ptak
- Southern Research Institute, 431 Aviation Way, Frederick, Maryland 21701, USA
| | - Nicholas P Farrell
- Department of Chemistry, Virginia Commonwealth University, Richmond, VA 23284-2006, USA.
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119
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Lama D, Pradhan MR, Brown CJ, Eapen RS, Joseph TL, Kwoh CK, Lane DP, Verma CS. Water-Bridge Mediates Recognition of mRNA Cap in eIF4E. Structure 2016; 25:188-194. [PMID: 27916520 DOI: 10.1016/j.str.2016.11.006] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2016] [Revised: 09/19/2016] [Accepted: 11/07/2016] [Indexed: 11/24/2022]
Abstract
Ligand binding pockets in proteins contain water molecules, which play important roles in modulating protein-ligand interactions. Available crystallographic data for the 5' mRNA cap-binding pocket of the translation initiation factor protein eIF4E shows several structurally conserved waters, which also persist in molecular dynamics simulations. These waters engage an intricate hydrogen-bond network between the cap and protein. Two crystallographic waters in the cleft of the pocket show a high degree of conservation and bridge two residues, which are part of an evolutionarily conserved scaffold. This appears to be a preformed recognition module for the cap with the two structural waters facilitating an efficient interaction. This is also recapitulated in a new crystal structure of the apo protein. These findings open new windows for the design and screening of compounds targeting eIF4E.
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Affiliation(s)
- Dilraj Lama
- Bioinformatics Institute, A(∗)STAR (Agency for Science, Technology and Research), 30 Biopolis Street, #07-01 Matrix, Singapore 138671, Singapore.
| | - Mohan R Pradhan
- Bioinformatics Institute, A(∗)STAR (Agency for Science, Technology and Research), 30 Biopolis Street, #07-01 Matrix, Singapore 138671, Singapore; School of Computer Engineering, Nanyang Technological University, 50 Nanyang Avenue, Singapore 639798, Singapore
| | - Christopher J Brown
- p53 Laboratory, A(∗)STAR (Agency for Science, Technology and Research), 8A Biomedical Grove, #06-04/05, Neuros/Immunos, Singapore 138648, Singapore
| | - Rohan S Eapen
- School of Molecular and Cellular Biology, University of Leeds, Leeds LS2 9JT, UK
| | - Thomas L Joseph
- Bioinformatics Institute, A(∗)STAR (Agency for Science, Technology and Research), 30 Biopolis Street, #07-01 Matrix, Singapore 138671, Singapore
| | - Chee-Keong Kwoh
- School of Computer Engineering, Nanyang Technological University, 50 Nanyang Avenue, Singapore 639798, Singapore
| | - David P Lane
- p53 Laboratory, A(∗)STAR (Agency for Science, Technology and Research), 8A Biomedical Grove, #06-04/05, Neuros/Immunos, Singapore 138648, Singapore
| | - Chandra S Verma
- Bioinformatics Institute, A(∗)STAR (Agency for Science, Technology and Research), 30 Biopolis Street, #07-01 Matrix, Singapore 138671, Singapore; Department of Biological Sciences, National University of Singapore, 14 Science Drive 4, Singapore 117543, Singapore; School of Biological Sciences, Nanyang Technological University, 50 Nanyang Drive, Singapore 637551, Singapore.
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120
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Xu C, Ishikawa H, Izumikawa K, Li L, He H, Nobe Y, Yamauchi Y, Shahjee HM, Wu XH, Yu YT, Isobe T, Takahashi N, Min J. Structural insights into Gemin5-guided selection of pre-snRNAs for snRNP assembly. Genes Dev 2016; 30:2376-2390. [PMID: 27881600 PMCID: PMC5131778 DOI: 10.1101/gad.288340.116] [Citation(s) in RCA: 47] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2016] [Accepted: 09/26/2016] [Indexed: 12/26/2022]
Abstract
Xu et al. show that the WD40 domain of Gemin5 is both necessary and sufficient for binding the Sm site of pre-snRNAs. They also determined the crystal structures of the WD40 domain of Gemin5 in complex with the Sm site or m7G cap of pre-snRNA. In cytoplasm, the survival of motor neuron (SMN) complex delivers pre-small nuclear RNAs (pre-snRNAs) to the heptameric Sm ring for the assembly of the ring complex on pre-snRNAs at the conserved Sm site [A(U)4–6G]. Gemin5, a WD40 protein component of the SMN complex, is responsible for recognizing pre-snRNAs. In addition, Gemin5 has been reported to specifically bind to the m7G cap. In this study, we show that the WD40 domain of Gemin5 is both necessary and sufficient for binding the Sm site of pre-snRNAs by isothermal titration calorimetry (ITC) and mutagenesis assays. We further determined the crystal structures of the WD40 domain of Gemin5 in complex with the Sm site or m7G cap of pre-snRNA, which reveal that the WD40 domain of Gemin5 recognizes the Sm site and m7G cap of pre-snRNAs via two distinct binding sites by respective base-specific interactions. In addition, we also uncovered a novel role of Gemin5 in escorting the truncated forms of U1 pre-snRNAs for proper disposal. Overall, the elucidated Gemin5 structures will contribute to a better understanding of Gemin5 in small nuclear ribonucleic protein (snRNP) biogenesis as well as, potentially, other cellular activities.
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Affiliation(s)
- Chao Xu
- Hefei National Laboratory for Physical Sciences at Microscale, Hefei Science Center of CAS, Chinese Academy of Science, School of Life Sciences, University of Science and Technology of China, Hefei, Anhui 230027, People's Republic of China.,Key Laboratory of Structural Biology, Hefei Science Center of CAS, Chinese Academy of Science, School of Life Sciences, University of Science and Technology of China, Hefei, Anhui 230027, People's Republic of China.,Structural Genomics Consortium, University of Toronto, Toronto, Ontario M5G 1L7, Canada
| | - Hideaki Ishikawa
- Department of Applied Biological Science, Graduate School of Agriculture and Global Innovation Research Organization, Tokyo University of Agriculture and Technology, Fuchu-Shi, Tokyo 183-8509, Japan
| | - Keiichi Izumikawa
- Department of Applied Biological Science, Graduate School of Agriculture and Global Innovation Research Organization, Tokyo University of Agriculture and Technology, Fuchu-Shi, Tokyo 183-8509, Japan
| | - Li Li
- Structural Genomics Consortium, University of Toronto, Toronto, Ontario M5G 1L7, Canada
| | - Hao He
- Structural Genomics Consortium, University of Toronto, Toronto, Ontario M5G 1L7, Canada
| | - Yuko Nobe
- Department of Chemistry, Tokyo Metropolitan University, Hachiouji-shi, Tokyo 192-0397, Japan
| | - Yoshio Yamauchi
- Department of Chemistry, Tokyo Metropolitan University, Hachiouji-shi, Tokyo 192-0397, Japan
| | - Hanief M Shahjee
- Department of Biochemistry and Biophysics, Center for RNA Biology, University of Rochester School of Medicine and Dentistry, Rochester, New York 14642, USA
| | - Xian-Hui Wu
- Structural Genomics Consortium, University of Toronto, Toronto, Ontario M5G 1L7, Canada
| | - Yi-Tao Yu
- Department of Biochemistry and Biophysics, Center for RNA Biology, University of Rochester School of Medicine and Dentistry, Rochester, New York 14642, USA
| | - Toshiaki Isobe
- Department of Chemistry, Tokyo Metropolitan University, Hachiouji-shi, Tokyo 192-0397, Japan
| | - Nobuhiro Takahashi
- Department of Applied Biological Science, Graduate School of Agriculture and Global Innovation Research Organization, Tokyo University of Agriculture and Technology, Fuchu-Shi, Tokyo 183-8509, Japan
| | - Jinrong Min
- Structural Genomics Consortium, University of Toronto, Toronto, Ontario M5G 1L7, Canada.,Department of Physiology, University of Toronto, Toronto, Ontario M5S 1A8, Canada
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121
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Tsotsoros SD, Lutz PB, Daniel AG, Peterson EJ, de Paiva REF, Rivera E, Qu Y, Bayse CA, Farrell NP. Enhancement of the physicochemical properties of [Pt(dien)(nucleobase)] 2+ for HIVNCp7 targeting. Chem Sci 2016; 8:1269-1281. [PMID: 28451269 PMCID: PMC5369524 DOI: 10.1039/c6sc03445d] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2016] [Accepted: 10/06/2016] [Indexed: 12/31/2022] Open
Abstract
Physicochemical properties of coordination compounds can be exploited for molecular recognition of biomolecules. The inherent π-π stacking properties of [Pt(chelate)(N-donor)]2+ ([PtN4]) complexes were modulated by systematic variation of the chelate (diethylenetriamine and substituted derivatives) and N-donor (nucleobase or nucleoside) in the formally substitution-inert PtN4 coordination sphere. Approaches to target the HIV nucleocapsid protein HIVNCp7 are summarized building on (i) assessment of stacking interactions with simple tryptophan or tryptophan derivatives to (ii) the tryptophan-containing C-terminal zinc finger and (iii) to the full two-zinc finger peptide and its interactions with RNA and DNA. The xanthosine nucleoside was identified as having significantly enhanced stacking capability over guanosine. Correlation of the LUMO energies of the modified nucleobases with the DFT π-stacking energies shows that frontier orbital energies of the individual monomers can be used as a first estimate of the π-stacking strength to Trp. Cellular accumulation studies showed no significant correlation with lipophilicity of the compounds, but all compounds had very low cytotoxicity suggesting the potential for antiviral selectivity. The conceptual similarities between nucleobase alkylation and platination validates the design of formally substitution-inert coordination complexes as weak Lewis acid electrophiles for selective peptide targeting.
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Affiliation(s)
- S D Tsotsoros
- Department of Chemistry , Virginia Commonwealth University , 1001 W. Main Street , Richmond , VA 23284-2006 , USA .
| | - P B Lutz
- Department of Science , Technology and Mathematics , Regent University , Virginia Beach , Virginia 23464 , USA.,Department of Chemistry and Biochemistry , Old Dominion University , Norfolk , VA 23529 , USA .
| | - A G Daniel
- Department of Chemistry , Virginia Commonwealth University , 1001 W. Main Street , Richmond , VA 23284-2006 , USA .
| | - E J Peterson
- Department of Chemistry , Virginia Commonwealth University , 1001 W. Main Street , Richmond , VA 23284-2006 , USA . .,Massey Cancer Center , Virginia Commonwealth University , Richmond , VA , USA
| | - R E F de Paiva
- Department of Chemistry , Virginia Commonwealth University , 1001 W. Main Street , Richmond , VA 23284-2006 , USA .
| | - E Rivera
- Department of Chemistry , Virginia Commonwealth University , 1001 W. Main Street , Richmond , VA 23284-2006 , USA .
| | - Y Qu
- Department of Chemistry , Virginia Commonwealth University , 1001 W. Main Street , Richmond , VA 23284-2006 , USA .
| | - C A Bayse
- Department of Chemistry and Biochemistry , Old Dominion University , Norfolk , VA 23529 , USA .
| | - N P Farrell
- Department of Chemistry , Virginia Commonwealth University , 1001 W. Main Street , Richmond , VA 23284-2006 , USA . .,Massey Cancer Center , Virginia Commonwealth University , Richmond , VA , USA
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122
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Structural basis of mRNA-cap recognition by Dcp1-Dcp2. Nat Struct Mol Biol 2016; 23:987-994. [PMID: 27694842 PMCID: PMC5113729 DOI: 10.1038/nsmb.3301] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2016] [Accepted: 09/01/2016] [Indexed: 11/21/2022]
Abstract
Removal of the 5′ cap on mRNA by the decapping enzyme Dcp2 is a critical step in 5′-to-3′ mRNA decay. Understanding the structural basis of Dcp2 activity has been a significant challenge because Dcp2 is dynamic, with weak affinity for cap substrate. Here we present a 2.6-Å-resolution crystal structure of a heterotrimer of fission yeast Dcp2, its essential activator Dcp1, and the human NMD cofactor PNRC2, in complex with a tight-binding cap analog. Cap binding is accompanied by a conformational change of Dcp2 to form a composite nucleotide binding site using conserved residues on the catalytic and regulatory domains. Kinetic analysis of PNRC2 reveals a conserved short linear motif enhances both substrate affinity and the catalytic step of decapping. These findings explain why Dcp2 requires a conformational change for efficient catalysis and reveals that coactivators can promote RNA binding and the catalytic step of decapping, possibly through different conformational states.
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123
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Curran JA, Weiss B. What Is the Impact of mRNA 5' TL Heterogeneity on Translational Start Site Selection and the Mammalian Cellular Phenotype? Front Genet 2016; 7:156. [PMID: 27630668 PMCID: PMC5005323 DOI: 10.3389/fgene.2016.00156] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2016] [Accepted: 08/16/2016] [Indexed: 12/23/2022] Open
Abstract
A major determinant in the efficiency of ribosome loading onto mRNAs is the 5′ TL (transcript leader or 5′ UTR). In addition, elements within this region also impact on start site selection demonstrating that it can modulate the protein readout at both quantitative and qualitative levels. With the increasing wealth of data generated by the mining of the mammalian transcriptome, it has become evident that a genes 5′ TL is not homogeneous but actually exhibits significant heterogeneity. This arises due to the utilization of alternative promoters, and is further compounded by significant variability with regards to the precise transcriptional start sites of each (not to mention alternative splicing). Consequently, the transcript for a protein coding gene is not a unique mRNA, but in-fact a complexed quasi-species of variants whose composition may respond to the changing physiological environment of the cell. Here we examine the potential impact of these events with regards to the protein readout.
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Affiliation(s)
- Joseph A Curran
- Department of Microbiology and Molecular Medicine, Medical School, University of GenevaGeneva, Switzerland; Institute of Genetics and Genomics of Geneva, University of GenevaGeneva, Switzerland
| | - Benjamin Weiss
- Department of Microbiology and Molecular Medicine, Medical School, University of Geneva Geneva, Switzerland
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124
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Design of nucleotide-mimetic and non-nucleotide inhibitors of the translation initiation factor eIF4E: Synthesis, structural and functional characterisation. Eur J Med Chem 2016; 124:200-217. [PMID: 27592390 PMCID: PMC5111791 DOI: 10.1016/j.ejmech.2016.08.047] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2016] [Revised: 08/03/2016] [Accepted: 08/21/2016] [Indexed: 12/02/2022]
Abstract
Eukaryotic translation initiation factor 4E (eIF4E) is considered as the corner stone in the cap-dependent translation initiation machinery. Its role is to recruit mRNA to the ribosome through recognition of the 5′-terminal mRNA cap structure (m7GpppN, where G is guanosine, N is any nucleotide). eIF4E is implicated in cell transformation, tumourigenesis, and angiogenesis by facilitating translation of oncogenic mRNAs; it is thus regarded as an attractive anticancer drug target. We have used two approaches to design cap-binding inhibitors of eIF4E by modifying the N7-substituent of m7GMP and replacing the phosphate group with isosteres such as squaramides, sulfonamides, and tetrazoles, as well as by structure-based virtual screening aimed at identifying non-nucleotide cap-binding antagonists. Phosphomimetic nucleotide derivatives and highly ranking virtual hits were evaluated in a series of in vitro and cell-based assays to identify the first non-nucleotide eIF4E cap-binding inhibitor with activities in cell-based assays, N-[(5,6-dihydro-6-oxo-1,3-dioxolo[4,5-g]quinolin-7-yl)methyl]-N′-(2-methyl-propyl)-N-(phenyl-methyl)thiourea (14), including down-regulation of oncogenic proteins and suppression of RNA incorporation into polysomes. Although we did not observe cellular activity with any of our modified m7GMP phosphate isostere compounds, we obtained X-ray crystallography structures of three such compounds in complex with eIF4E, 5′-deoxy-5′-(1,2-dioxo-3-hydroxycyclobut-3-en-4-yl)amino-N7-methyl-guanosine (4a), N7-3-chlorobenzyl-5′-deoxy-5′-(1,2-dioxo-3-hydroxy-cyclobut-3-en-4-yl)amino-guanosine (4f), and N7-benzyl-5′-deoxy-5′-(trifluoromethyl-sulfamoyl)guanosine (7a). Collectively, the data we present on structure-based design of eIF4E cap-binding inhibitors should facilitate the optimisation of such compounds as potential anticancer agents.
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125
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Holstein JM, Anhäuser L, Rentmeister A. Modifying the 5'-Cap for Click Reactions of Eukaryotic mRNA and To Tune Translation Efficiency in Living Cells. Angew Chem Int Ed Engl 2016; 55:10899-903. [PMID: 27511141 DOI: 10.1002/anie.201604107] [Citation(s) in RCA: 76] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2016] [Revised: 06/21/2016] [Indexed: 11/06/2022]
Abstract
The 5'-cap is a hallmark of eukaryotic mRNAs and plays fundamental roles in RNA metabolism, ranging from quality control to export and translation. Modifying the 5'-cap may thus enable modulation of the underlying processes and investigation or tuning of several biological functions. A straightforward approach is presented for the efficient production of a range of N7-modified caps based on the highly promiscuous methyltransferase Ecm1. We show that these, as well as N(2) -modified 5'-caps, can be used to tune translation of the respective mRNAs both in vitro and in cells. Appropriate modifications allow subsequent bioorthogonal chemistry, as demonstrated by intracellular live-cell labeling of a target mRNA. The efficient and versatile N7 manipulation of the mRNA cap makes mRNAs amenable to both modulation of their biological function and intracellular labeling, and represents a valuable addition to the chemical biology toolbox.
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Affiliation(s)
- Josephin M Holstein
- University of Muenster, Department of Chemistry, Institute of Biochemistry, Wilhelm-Klemm-Strasse 2, 48149, Muenster, Germany
| | - Lea Anhäuser
- University of Muenster, Department of Chemistry, Institute of Biochemistry, Wilhelm-Klemm-Strasse 2, 48149, Muenster, Germany
| | - Andrea Rentmeister
- University of Muenster, Department of Chemistry, Institute of Biochemistry, Wilhelm-Klemm-Strasse 2, 48149, Muenster, Germany. .,Cells-in-Motion Cluster of Excellence (EXC 1003-CiM), University of Muenster, Germany.
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126
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Holstein JM, Anhäuser L, Rentmeister A. Modifizierung der 5′-Kappe eukaryotischer mRNA für Klick-Reaktionen und zur Beeinflussung der Translationseffizienz in lebenden Zellen. Angew Chem Int Ed Engl 2016. [DOI: 10.1002/ange.201604107] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Affiliation(s)
- Josephin M. Holstein
- Westfälische Wilhelms-Universität Münster; Fachbereich Chemie und Pharmazie; Institut für Biochemie; Wilhelm-Klemm-Straße 2 48149 Münster Deutschland
| | - Lea Anhäuser
- Westfälische Wilhelms-Universität Münster; Fachbereich Chemie und Pharmazie; Institut für Biochemie; Wilhelm-Klemm-Straße 2 48149 Münster Deutschland
| | - Andrea Rentmeister
- Westfälische Wilhelms-Universität Münster; Fachbereich Chemie und Pharmazie; Institut für Biochemie; Wilhelm-Klemm-Straße 2 48149 Münster Deutschland
- Cells-in-Motion Cluster of Excellence (EXC 1003 - CiM); Westfälische Wilhelms-Universität Münster; Deutschland
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127
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Borden KLB. The eukaryotic translation initiation factor eIF4E wears a "cap" for many occasions. ACTA ACUST UNITED AC 2016; 4:e1220899. [PMID: 28090419 PMCID: PMC5173310 DOI: 10.1080/21690731.2016.1220899] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2016] [Revised: 07/12/2016] [Accepted: 08/02/2016] [Indexed: 01/11/2023]
Abstract
The eukaryotic translation initiation factor eIF4E plays important roles in controlling the composition of the proteome. Indeed, dysregulation of eIF4E is associated with poor prognosis cancers. The traditional view has been that eIF4E acts solely in translation. However, over the last ∼25 years, eIF4E was found in the nucleus where it acts in mRNA export and in the last ∼10 years, eIF4E was found in cytoplasmic processing bodies (P-bodies) where it functions in mRNA sequestration and stability. The common biochemical thread for these activities is the ability of eIF4E to bind the 7-methylguanosine cap on the 5′ end of mRNAs. Recently, the possibility that eIF4E directly binds some mRNA elements independently of the cap has also been raised. Importantly, the effects of eIF4E are not genome-wide with a subset of transcripts targeted depending on the presence of specific mRNA elements and context-dependent regulatory factors. Indeed, eIF4E governs RNA regulons through co-regulating the expression of groups of transcripts acting in the same biochemical pathways. In addition, studies over the past ∼15 years indicate that there are multiple strategies that regulatory factors employ to modulate eIF4E activities in context-dependent manners. This perspective focuses on these new findings and incorporates them into a broader model for eIF4E function.
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Affiliation(s)
- Katherine L B Borden
- Department of Pathology and Cell Biology, Institute of Research in Immunology and Cancer (IRIC), Université de Montréal , Montreal, Québec, Canada
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128
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Mutagenesis of S-Adenosyl-l-Methionine-Binding Residues in Coronavirus nsp14 N7-Methyltransferase Demonstrates Differing Requirements for Genome Translation and Resistance to Innate Immunity. J Virol 2016; 90:7248-7256. [PMID: 27252528 PMCID: PMC4984653 DOI: 10.1128/jvi.00542-16] [Citation(s) in RCA: 47] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2016] [Accepted: 05/24/2016] [Indexed: 12/23/2022] Open
Abstract
UNLABELLED Eukaryotic mRNAs possess a methylated 5'-guanosine cap that is required for RNA stability, efficient translation, and protection from cell-intrinsic defenses. Many viruses use 5' caps or other mechanisms to mimic a cap structure to limit detection of viral RNAs by intracellular innate sensors and to direct efficient translation of viral proteins. The coronavirus (CoV) nonstructural protein 14 (nsp14) is a multifunctional protein with N7-methyltransferase (N7-MTase) activity. The highly conserved S-adenosyl-l-methionine (SAM)-binding residues of the DxG motif are required for nsp14 N7-MTase activity in vitro However, the requirement for CoV N7-MTase activity and the importance of the SAM-binding residues during viral replication have not been determined. Here, we engineered mutations in murine hepatitis virus (MHV) nsp14 N7-MTase at residues D330 and G332 and determined the effects of these mutations on viral replication, sensitivity to mutagen, inhibition by type I interferon (IFN), and translation efficiency. Virus encoding a G332A substitution in nsp14 displayed delayed replication kinetics and decreased peak titers relative to wild-type (WT) MHV. In addition, replication of nsp14 G332A virus was diminished following treatment of cells with IFN-β, and nsp14 G332A genomes were translated less efficiently both in vitro and during viral infection. In contrast, substitution of alanine at MHV nsp14 D330 did not affect viral replication, sensitivity to mutagen, or inhibition by IFN-β compared to WT MHV. Our results demonstrate that the conserved MHV N7-MTase SAM-binding-site residues are not required for MHV viability and suggest that the determinants of CoV N7-MTase activity differ in vitro and during virus infection. IMPORTANCE Human coronaviruses, most notably severe acute respiratory syndrome (SARS)-CoV and Middle East respiratory syndrome (MERS)-CoV, cause severe and lethal human disease. Since specific antiviral therapies are not available for the treatment of human coronavirus infections, it is essential to understand the functions of conserved CoV proteins in viral replication. Here, we show that substitution of alanine at G332 in the N7-MTase domain of nsp14 impairs viral replication, enhances sensitivity to the innate immune response, and reduces viral RNA translation efficiency. Our data support the idea that coronavirus RNA capping could be targeted for development of antiviral therapeutics.
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129
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Zuberek J, Kuchta K, Hernández G, Sonenberg N, Ginalski K. Diverse cap-binding properties of Drosophila eIF4E isoforms. BIOCHIMICA ET BIOPHYSICA ACTA-PROTEINS AND PROTEOMICS 2016; 1864:1292-303. [PMID: 27374989 DOI: 10.1016/j.bbapap.2016.06.015] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Received: 06/07/2016] [Accepted: 06/28/2016] [Indexed: 10/21/2022]
Abstract
The majority of eukaryotic mRNAs are translated in a cap-dependent manner, which requires recognition of the mRNA 5' cap by eIF4E protein. Multiple eIF4E family members have been identified in most eukaryotic organisms. Drosophila melanogaster (Dm) has eight eIF4E related proteins; seven of them belong to Class I and one to Class II. Their biological roles with the exception of Dm eIF4E-1, Dm eIF4E-3 and Dm 4EHP, remain unknown. Here, we compare the molecular basis of Dm eIF4E's interactions with cap and eIF4G peptide by using homology modelling and fluorescence binding assays with various cap analogues. We found that despite the presence of conserved key residues responsible for cap recognition, the differences in binding different cap analogues among Class I Dm eIF4E isoforms are up to 14-fold. The highest affinity for cap analogues was observed for Dm eIF4E-3. We suggest that Dm eIF4E-3 and Dm eIF4E-5 bind the second nucleoside of the cap in an unusual manner via stacking interactions with a histidine or a phenylalanine residue, respectively. Moreover, the analysis of ternary complexes of eIF4G peptide-eIF4E-cap analogue showed cooperativity between eIF4G and cap binding only for Dm eIF4E-4, which exhibits the lowest affinity for cap analogues among all Dm eIF4Es.
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Affiliation(s)
- Joanna Zuberek
- Division of Biophysics, Institute of Experimental Physics, Faculty of Physics, University of Warsaw, Warsaw 02-089, Poland.
| | - Krzysztof Kuchta
- Laboratory of Bioinformatics and Systems Biology, Centre of New Technologies, University of Warsaw, Warsaw 02-097, Poland; College of Inter-Faculty Individual Studies in Mathematics and Natural Sciences, University of Warsaw, Warsaw 02-089, Poland.
| | - Greco Hernández
- Division of Basic Research, National Institute of Cancer (INCan), Tlalpan, Mexico City 14080, Mexico.
| | - Nahum Sonenberg
- Department of Biochemistry and Goodman Cancer Research Centre, McGill University, Montreal, QC H3A 1A3, Canada.
| | - Krzysztof Ginalski
- Laboratory of Bioinformatics and Systems Biology, Centre of New Technologies, University of Warsaw, Warsaw 02-097, Poland.
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130
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The molecular choreography of protein synthesis: translational control, regulation, and pathways. Q Rev Biophys 2016; 49:e11. [PMID: 27658712 DOI: 10.1017/s0033583516000056] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Translation of proteins by the ribosome regulates gene expression, with recent results underscoring the importance of translational control. Misregulation of translation underlies many diseases, including cancer and many genetic diseases. Decades of biochemical and structural studies have delineated many of the mechanistic details in prokaryotic translation, and sketched the outlines of eukaryotic translation. However, translation may not proceed linearly through a single mechanistic pathway, but likely involves multiple pathways and branchpoints. The stochastic nature of biological processes would allow different pathways to occur during translation that are biased by the interaction of the ribosome with other translation factors, with many of the steps kinetically controlled. These multiple pathways and branchpoints are potential regulatory nexus, allowing gene expression to be tuned at the translational level. As research focus shifts toward eukaryotic translation, certain themes will be echoed from studies on prokaryotic translation. This review provides a general overview of the dynamic data related to prokaryotic and eukaryotic translation, in particular recent findings with single-molecule methods, complemented by biochemical, kinetic, and structural findings. We will underscore the importance of viewing the process through the viewpoints of regulation, translational control, and heterogeneous pathways.
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131
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BTG4 is a meiotic cell cycle-coupled maternal-zygotic-transition licensing factor in oocytes. Nat Struct Mol Biol 2016; 23:387-94. [PMID: 27065194 DOI: 10.1038/nsmb.3204] [Citation(s) in RCA: 158] [Impact Index Per Article: 19.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2015] [Accepted: 03/11/2016] [Indexed: 12/29/2022]
Abstract
The mRNAs stored in oocytes undergo general decay during the maternal-zygotic transition (MZT), and their stability is tightly interconnected with meiotic cell-cycle progression. However, the factors that trigger decay of maternal mRNA and couple this event to oocyte meiotic maturation remain elusive. Here, we identified B-cell translocation gene-4 (BTG4) as an MZT licensing factor in mice. BTG4 bridged CNOT7, a catalytic subunit of the CCR4-NOT deadenylase, to eIF4E, a key translation initiation factor, and facilitated decay of maternal mRNA. Btg4-null females produced morphologically normal oocytes but were infertile, owing to early developmental arrest. The intrinsic MAP kinase cascade in oocytes triggered translation of Btg4 mRNA stored in fully grown oocytes by targeting the 3' untranslated region, thereby coupling CCR4-NOT deadenylase-mediated decay of maternal mRNA with oocyte maturation and fertilization. This is a key step in oocyte cytoplasmic maturation that determines the developmental potential of mammalian embryos.
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132
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Chuang TW, Lee KM, Lou YC, Lu CC, Tarn WY. A Point Mutation in the Exon Junction Complex Factor Y14 Disrupts Its Function in mRNA Cap Binding and Translation Enhancement. J Biol Chem 2016; 291:8565-74. [PMID: 26887951 DOI: 10.1074/jbc.m115.704544] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2015] [Indexed: 12/17/2022] Open
Abstract
Eukaryotic mRNA biogenesis involves a series of interconnected steps mediated by RNA-binding proteins. The exon junction complex core protein Y14 is required for nonsense-mediated mRNA decay (NMD) and promotes translation. Moreover, Y14 binds the cap structure of mRNAs and inhibits the activity of the decapping enzyme Dcp2. In this report, we show that an evolutionarily conserved tryptophan residue (Trp-73) of Y14 is critical for its binding to the mRNA cap structure. A Trp-73 mutant (W73V) bound weakly to mRNAs and failed to protect them from degradation. However, this mutant could still interact with the NMD and mRNA degradation factors and retained partial NMD activity. In addition, we found that the W73V mutant could not interact with translation initiation factors. Overexpression of W73V suppressed reporter mRNA translation in vitro and in vivo and reduced the level of a set of nascent proteins. These results reveal a residue of Y14 that confers cap-binding activity and is essential for Y14-mediated enhancement of translation. Finally, we demonstrated that Y14 may selectively and differentially modulate protein biosynthesis.
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Affiliation(s)
- Tzu-Wei Chuang
- From the Institute of Biomedical Sciences, Academia Sinica, Taipei 11529, Taiwan
| | - Kuo-Ming Lee
- From the Institute of Biomedical Sciences, Academia Sinica, Taipei 11529, Taiwan
| | - Yuan-Chao Lou
- From the Institute of Biomedical Sciences, Academia Sinica, Taipei 11529, Taiwan
| | - Chia-Chen Lu
- From the Institute of Biomedical Sciences, Academia Sinica, Taipei 11529, Taiwan
| | - Woan-Yuh Tarn
- From the Institute of Biomedical Sciences, Academia Sinica, Taipei 11529, Taiwan
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133
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Uchida H, Itaka K, Uchida S, Ishii T, Suma T, Miyata K, Oba M, Nishiyama N, Kataoka K. Synthetic Polyamines to Regulate mRNA Translation through the Preservative Binding of Eukaryotic Initiation Factor 4E to the Cap Structure. J Am Chem Soc 2016; 138:1478-81. [PMID: 26811205 DOI: 10.1021/jacs.5b11726] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Polyion complexes (PICs) of mRNA with synthetic polyamines are receiving increasing attention as mRNA delivery vehicles, and the search for polyamine structure maximizing the translational efficiency of complexed mRNA becomes a critical research topic. Herein, we discovered that fine-tuning of the protonation status of synthetic polyamines can regulate mRNA translation through the preservative binding of eukaryotic initiation factor 4E to m(7)GpppN (cap structure) on the 5' end of mRNA. A series of polyamines with varied numbers of aminoethylene repeats in their side chains were prepared by an aminolysis reaction of poly(β-benzyl-l-aspartate) and paired with mRNA to form PICs. PICs formed from polyamines with higher numbers of aminoethylene repeats preserved the original translational efficiency to naked mRNA, whereas the efficiency significantly dropped by decreasing the number of aminoethylene repeats in the polyamines. Immunoprecipitation assays using anti-eIF4E antibodies revealed that the binding affinity of eIF4E to the cap structure of mRNA in the PIC was sensitive to the number of charged aminoethylene repeats in the polyamine side chain and was strongly correlated with their translational efficiency. These results indicate that the fine-tuning of the polyamine structure plays a critical role in maximizing the translational efficiency of mRNA in the PICs having potential utility as mRNA delivery vehicles.
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Affiliation(s)
| | | | | | | | - Tomoya Suma
- Department of Chemical and Biomolecular Engineering, The University of Melbourne , Melbourne, Victoria 3010, Australia
| | | | - Makoto Oba
- Graduate School of Biomedical Sciences, Nagasaki University , 1-14 Bunkyo-machi, Nagasaki 852-8521, Japan
| | - Nobuhiro Nishiyama
- Polymer Chemistry Division, Chemical Resources Laboratory, Tokyo Institute of Technology , R1-11, 4529 Nagatsuta, Midori-ku, Yokohama 226-8503, Japan
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134
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Molecular recognition of mRNA 5' cap by 3' poly(A)-specific ribonuclease (PARN) differs from interactions known for other cap-binding proteins. BIOCHIMICA ET BIOPHYSICA ACTA-PROTEINS AND PROTEOMICS 2016; 1864:331-45. [PMID: 26772900 DOI: 10.1016/j.bbapap.2016.01.002] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Received: 09/30/2015] [Revised: 12/23/2015] [Accepted: 01/05/2016] [Indexed: 12/30/2022]
Abstract
The mRNA 5' cap structure plays a pivotal role in coordination of eukaryotic translation and mRNA degradation. Poly(A)-specific ribonuclease (PARN) is a dimeric exoribonuclease that efficiently degrades mRNA 3' poly(A) tails while also simultaneously interacting with the mRNA 5' cap. The cap binding amplifies the processivity of PARN action. We used surface plasmon resonance kinetic analysis, quantitative equilibrium fluorescence titrations and circular dichroism to study the cap binding properties of PARN. The molecular mechanism of 5' cap recognition by PARN has been demonstrated to differ from interactions seen for other known cap-binding proteins in that: i) the auxiliary biological function of 5' cap binding by the 3' degrading enzyme is accomplished by negative cooperativity of PARN dimer subunits; ii) non-coulombic interactions are major factors in the complex formation; and iii) PARN has versatile activity toward alternative forms of the cap. These characteristics contribute to stabilization of the PARN-cap complex needed for the deadenylation processivity. Our studies provide a consistent biophysical basis for elucidation of the processive mechanism of PARN-mediated 3' mRNA deadenylation and provide a new framework to interpret the role of the 5' cap in mRNA degradation.
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135
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Structural basis for m7G recognition and 2'-O-methyl discrimination in capped RNAs by the innate immune receptor RIG-I. Proc Natl Acad Sci U S A 2016; 113:596-601. [PMID: 26733676 DOI: 10.1073/pnas.1515152113] [Citation(s) in RCA: 229] [Impact Index Per Article: 28.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
RNAs with 5'-triphosphate (ppp) are detected in the cytoplasm principally by the innate immune receptor Retinoic Acid Inducible Gene-I (RIG-I), whose activation triggers a Type I IFN response. It is thought that self RNAs like mRNAs are not recognized by RIG-I because 5'ppp is capped by the addition of a 7-methyl guanosine (m7G) (Cap-0) and a 2'-O-methyl (2'-OMe) group to the 5'-end nucleotide ribose (Cap-1). Here we provide structural and mechanistic basis for exact roles of capping and 2'-O-methylation in evading RIG-I recognition. Surprisingly, Cap-0 and 5'ppp double-stranded (ds) RNAs bind to RIG-I with nearly identical Kd values and activate RIG-I's ATPase and cellular signaling response to similar extents. On the other hand, Cap-0 and 5'ppp single-stranded RNAs did not bind RIG-I and are signaling inactive. Three crystal structures of RIG-I complexes with dsRNAs bearing 5'OH, 5'ppp, and Cap-0 show that RIG-I can accommodate the m7G cap in a cavity created through conformational changes in the helicase-motif IVa without perturbing the ppp interactions. In contrast, Cap-1 modifications abrogate RIG-I signaling through a mechanism involving the H830 residue, which we show is crucial for discriminating between Cap-0 and Cap-1 RNAs. Furthermore, m7G capping works synergistically with 2'-O-methylation to weaken RNA affinity by 200-fold and lower ATPase activity. Interestingly, a single H830A mutation restores both high-affinity binding and signaling activity with 2'-O-methylated dsRNAs. Our work provides new structural insights into the mechanisms of host and viral immune evasion from RIG-I, explaining the complexity of cap structures over evolution.
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136
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Rhoads RE. Synthetic mRNA: Production, Introduction into Cells, and Physiological Consequences. Methods Mol Biol 2016; 1428:3-27. [PMID: 27236789 DOI: 10.1007/978-1-4939-3625-0_1] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Recent advances have made it possible to synthesize mRNA in vitro that is relatively stable when introduced into mammalian cells, has a diminished ability to activate the innate immune response against exogenous (virus-like) RNA, and can be efficiently translated into protein. Synthetic methods have also been developed to produce mRNA with unique investigational properties such as photo-cross-linking, fluorescence emission, and attachment of ligands through click chemistry. Synthetic mRNA has been proven effective in numerous applications beneficial for human health such as immunizing patients against cancer and infections diseases, alleviating diseases by restoring deficient proteins, converting somatic cells to pluripotent stem cells to use in regenerative medicine therapies, and engineering the genome by making specific alterations in DNA. This introductory chapter provides background information relevant to the following 20 chapters of this volume that present protocols for these applications of synthetic mRNA.
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Affiliation(s)
- Robert E Rhoads
- Department of Biochemistry and Molecular Biology, Louisiana State University Health Sciences Center, Shreveport, LA, 71130-3932, USA.
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137
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Fatscher T, Boehm V, Gehring NH. Mechanism, factors, and physiological role of nonsense-mediated mRNA decay. Cell Mol Life Sci 2015; 72:4523-44. [PMID: 26283621 PMCID: PMC11113733 DOI: 10.1007/s00018-015-2017-9] [Citation(s) in RCA: 67] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2015] [Revised: 07/10/2015] [Accepted: 08/06/2015] [Indexed: 02/04/2023]
Abstract
Nonsense-mediated mRNA decay (NMD) is a translation-dependent, multistep process that degrades irregular or faulty messenger RNAs (mRNAs). NMD mainly targets mRNAs with a truncated open reading frame (ORF) due to premature termination codons (PTCs). In addition, NMD also regulates the expression of different types of endogenous mRNA substrates. A multitude of factors are involved in the tight regulation of the NMD mechanism. In this review, we focus on the molecular mechanism of mammalian NMD. Based on the published data, we discuss the involvement of translation termination in NMD initiation. Furthermore, we provide a detailed overview of the core NMD machinery, as well as several peripheral NMD factors, and discuss their function. Finally, we present an overview of diseases associated with NMD factor mutations and summarize the current state of treatment for genetic disorders caused by nonsense mutations.
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Affiliation(s)
- Tobias Fatscher
- Institute for Genetics, University of Cologne, Cologne, Germany
| | - Volker Boehm
- Institute for Genetics, University of Cologne, Cologne, Germany
| | - Niels H Gehring
- Institute for Genetics, University of Cologne, Cologne, Germany.
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138
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Friday AJ, Henderson MA, Morrison JK, Hoffman JL, Keiper BD. Spatial and temporal translational control of germ cell mRNAs mediated by the eIF4E isoform IFE-1. J Cell Sci 2015; 128:4487-98. [PMID: 26542024 DOI: 10.1242/jcs.172684] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2015] [Accepted: 11/02/2015] [Indexed: 11/20/2022] Open
Abstract
Regulated mRNA translation is vital for germ cells to produce new proteins in the spatial and temporal patterns that drive gamete development. Translational control involves the de-repression of stored mRNAs and their recruitment by eukaryotic initiation factors (eIFs) to ribosomes. C. elegans expresses five eIF4Es (IFE-1-IFE-5); several have been shown to selectively recruit unique pools of mRNA. Individual IFE knockouts yield unique phenotypes due to inefficient translation of certain mRNAs. Here, we identified mRNAs preferentially translated through the germline-specific eIF4E isoform IFE-1. Differential polysome microarray analysis identified 77 mRNAs recruited by IFE-1. Among the IFE-1-dependent mRNAs are several required for late germ cell differentiation and maturation. Polysome association of gld-1, vab-1, vpr-1, rab-7 and rnp-3 mRNAs relies on IFE-1. Live animal imaging showed IFE-1-dependent selectivity in spatial and temporal translation of germline mRNAs. Altered MAPK activation in oocytes suggests dual roles for IFE-1, both promoting and suppressing oocyte maturation at different stages. This single eIF4E isoform exerts positive, selective translational control during germ cell differentiation.
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Affiliation(s)
- Andrew J Friday
- Department of Biochemistry and Molecular Biology, Brody School of Medicine at East Carolina University, Greenville, NC 27834, USA
| | - Melissa A Henderson
- Department of Molecular Sciences, DeBusk College of Osteopathic Medicine, Lincoln Memorial University, Harrogate, TN 37752, USA
| | - J Kaitlin Morrison
- Department of Biochemistry and Molecular Biology, Brody School of Medicine at East Carolina University, Greenville, NC 27834, USA
| | - Jenna L Hoffman
- Department of Biochemistry and Molecular Biology, Brody School of Medicine at East Carolina University, Greenville, NC 27834, USA
| | - Brett D Keiper
- Department of Biochemistry and Molecular Biology, Brody School of Medicine at East Carolina University, Greenville, NC 27834, USA
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139
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Lama D, Brown CJ, Lane DP, Verma CS. Gating by Tryptophan 73 Exposes a Cryptic Pocket at the Protein-Binding Interface of the Oncogenic eIF4E Protein. Biochemistry 2015; 54:6535-44. [DOI: 10.1021/acs.biochem.5b00812] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Affiliation(s)
- Dilraj Lama
- Bioinformatics
Institute, A*STAR (Agency for Science, Technology and Research), 30 Biopolis
Street, #07-01 Matrix, Singapore 138671
| | - Christopher J. Brown
- p53
Laboratory, A*STAR (Agency for Science, Technology and Research), 8A Biomedical Grove, #06-04/05, Neuros/Immunos, Singapore 138648
| | - David P. Lane
- p53
Laboratory, A*STAR (Agency for Science, Technology and Research), 8A Biomedical Grove, #06-04/05, Neuros/Immunos, Singapore 138648
| | - Chandra S. Verma
- Bioinformatics
Institute, A*STAR (Agency for Science, Technology and Research), 30 Biopolis
Street, #07-01 Matrix, Singapore 138671
- Department
of Biological Sciences, National University of Singapore, 14 Science
Drive 4, Singapore 117543
- School
of Biological Sciences, Nanyang Technological University, 50 Nanyang
Drive, Singapore 637551
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140
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de Melo Neto OP, da Costa Lima TDC, Xavier CC, Nascimento LM, Romão TP, Assis LA, Pereira MMC, Reis CRS, Papadopoulou B. The unique Leishmania EIF4E4 N-terminus is a target for multiple phosphorylation events and participates in critical interactions required for translation initiation. RNA Biol 2015; 12:1209-21. [PMID: 26338184 DOI: 10.1080/15476286.2015.1086865] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
The eukaryotic initiation factor 4E (eIF4E) recognizes the mRNA cap structure and, together with eIF4G and eIF4A, form the eIF4F complex that regulates translation initiation in eukaryotes. In trypanosomatids, 2 eIF4E homologues (EIF4E3 and EIF4E4) have been shown to be part of eIF4F-like complexes with presumed roles in translation initiation. Both proteins possess unique N-terminal extensions, which can be targeted for phosphorylation. Here, we provide novel insights on the Leishmania infantum EIF4E4 function and regulation. We show that EIF4E4 is constitutively expressed throughout the parasite development but is preferentially phosphorylated in exponentially grown promastigote and amastigote life stages, hence correlating with high levels of translation. Phosphorylation targets multiple serine-proline or threonine-proline residues within the N-terminal extension of EIF4E4 but does not require binding to the EIF4E4's partner, EIF4G3, or to the cap structure. We also report that EIF4E4 interacts with PABP1 through 3 conserved boxes at the EIF4E4 N-terminus and that this interaction is a prerequisite for efficient EIF4E4 phosphorylation. EIF4E4 is essential for Leishmania growth and an EIF4E4 null mutant was only obtained in the presence of an ectopically provided wild type gene. Complementation for the loss of EIF4E4 with several EIF4E4 mutant proteins affecting either phosphorylation or binding to mRNA or to EIF4E4 protein partners revealed that, in contrast to other eukaryotes, only the EIF4E4-PABP1 interaction but neither the binding to EIF4G3 nor phosphorylation is essential for translation. These studies also demonstrated that the lack of both EIF4E4 phosphorylation and EIF4G3 binding leads to a non-functional protein. Altogether, these findings further highlight the unique features of the translation initiation process in trypanosomatid protozoa.
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Affiliation(s)
- Osvaldo P de Melo Neto
- a Departamento de Microbiologia ; Centro de Pesquisas Aggeu Magalhães-FIOCRUZ ; Recife , PE , Brazil
| | - Tamara D C da Costa Lima
- a Departamento de Microbiologia ; Centro de Pesquisas Aggeu Magalhães-FIOCRUZ ; Recife , PE , Brazil
| | - Camila C Xavier
- a Departamento de Microbiologia ; Centro de Pesquisas Aggeu Magalhães-FIOCRUZ ; Recife , PE , Brazil
| | - Larissa M Nascimento
- a Departamento de Microbiologia ; Centro de Pesquisas Aggeu Magalhães-FIOCRUZ ; Recife , PE , Brazil.,b CHU de Quebec Research Center and Department of Microbiology ; Infectious Disease and Immunology; Laval University ; Quebec, QC , Canada
| | - Tatiany P Romão
- a Departamento de Microbiologia ; Centro de Pesquisas Aggeu Magalhães-FIOCRUZ ; Recife , PE , Brazil
| | - Ludmila A Assis
- a Departamento de Microbiologia ; Centro de Pesquisas Aggeu Magalhães-FIOCRUZ ; Recife , PE , Brazil
| | - Mariana M C Pereira
- a Departamento de Microbiologia ; Centro de Pesquisas Aggeu Magalhães-FIOCRUZ ; Recife , PE , Brazil
| | - Christian R S Reis
- a Departamento de Microbiologia ; Centro de Pesquisas Aggeu Magalhães-FIOCRUZ ; Recife , PE , Brazil
| | - Barbara Papadopoulou
- b CHU de Quebec Research Center and Department of Microbiology ; Infectious Disease and Immunology; Laval University ; Quebec, QC , Canada
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141
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Abstract
The original purification of the heterotrimeric eIF4F was published over 30 years ago (Grifo, J. A., Tahara, S. M., Morgan, M. A., Shatkin, A. J., and Merrick, W. C. (1983) J. Biol. Chem. 258, 5804-5810). Since that time, numerous studies have been performed with the three proteins specifically required for the translation initiation of natural mRNAs, eIF4A, eIF4B, and eIF4F. These have involved enzymatic and structural studies of the proteins and a number of site-directed mutagenesis studies. The regulation of translation exhibited through the mammalian target of rapamycin (mTOR) pathway is predominately seen as the phosphorylation of 4E-BP, an inhibitor of protein synthesis that functions by binding to the cap binding subunit of eIF4F (eIF4E). A hypothesis that requires the disassembly of eIF4F during translation initiation to yield free subunits (eIF4A, eIF4E, and eIF4G) is presented.
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Affiliation(s)
- William C Merrick
- From the Department of Biochemistry, School of Medicine, Case Western Reserve University, Cleveland, Ohio 44106-4935
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142
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Positive mRNA Translational Control in Germ Cells by Initiation Factor Selectivity. BIOMED RESEARCH INTERNATIONAL 2015; 2015:327963. [PMID: 26357652 PMCID: PMC4556832 DOI: 10.1155/2015/327963] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/18/2015] [Accepted: 07/22/2015] [Indexed: 01/04/2023]
Abstract
Ultimately, the production of new proteins in undetermined cells pushes them to new fates. Other proteins hold a stem cell in a mode of self-renewal. In germ cells, these decision-making proteins are produced largely from translational control of preexisting mRNAs. To date, all of the regulation has been attributed to RNA binding proteins (RBPs) that repress mRNAs in many models of germ cell development (Drosophila, mouse, C. elegans, and Xenopus). In this review, we focus on the selective, positive function of translation initiation factors eIF4E and eIF4G, which recruit mRNAs to ribosomes upon derepression. Evidence now shows that the two events are not separate but rather are coordinated through composite complexes of repressors and germ cell isoforms of eIF4 factors. Strikingly, the initiation factor isoforms are themselves mRNA selective. The mRNP complexes of translation factors and RBPs are built on specific populations of mRNAs to prime them for subsequent translation initiation. Simple rearrangement of the partners causes a dormant mRNP to become synthetically active in germ cells when and where they are required to support gametogenesis.
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143
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Osborne MJ, Borden KLB. The eukaryotic translation initiation factor eIF4E in the nucleus: taking the road less traveled. Immunol Rev 2015; 263:210-23. [PMID: 25510279 DOI: 10.1111/imr.12240] [Citation(s) in RCA: 46] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
The eukaryotic translation initiation factor eIF4E is a potent oncogene. Although eIF4E has traditional roles in translation initiation in the cytoplasm, it is also found in the nucleus, suggesting that it has activities beyond its role in protein synthesis. The road less traveled has been taken to study these nuclear activities and to understand their contribution to the oncogenic potential of eIF4E. The molecular features and biological pathways underpinning eIF4E's nuclear mRNA export are described. New classes of eIF4E regulators have been identified and their relevance to cancer shown. The studies presented here reveal the molecular, biophysical, and structural bases for eIF4E regulation. Finally, recent clinical work targeting eIF4E in acute myeloid leukemia patients with ribavirin is discussed. In summary, these findings provide a novel paradigm for eIF4E function and the molecular basis for targeting it in leukemia patients.
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Affiliation(s)
- Michael J Osborne
- Institute for Research in Immunology and Cancer & Dept. of Pathology and Cell Biology, Université de Montréal, Montréal, QC, Canada
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144
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Sekiyama N, Arthanari H, Papadopoulos E, Rodriguez-Mias RA, Wagner G, Léger-Abraham M. Molecular mechanism of the dual activity of 4EGI-1: Dissociating eIF4G from eIF4E but stabilizing the binding of unphosphorylated 4E-BP1. Proc Natl Acad Sci U S A 2015; 112:E4036-45. [PMID: 26170285 PMCID: PMC4522750 DOI: 10.1073/pnas.1512118112] [Citation(s) in RCA: 78] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
The eIF4E-binding protein (4E-BP) is a phosphorylation-dependent regulator of protein synthesis. The nonphosphorylated or minimally phosphorylated form binds translation initiation factor 4E (eIF4E), preventing binding of eIF4G and the recruitment of the small ribosomal subunit. Signaling events stimulate serial phosphorylation of 4E-BP, primarily by mammalian target of rapamycin complex 1 (mTORC1) at residues T37/T46, followed by T70 and S65. Hyperphosphorylated 4E-BP dissociates from eIF4E, allowing eIF4E to interact with eIF4G and translation initiation to resume. Because overexpression of eIF4E is linked to cellular transformation, 4E-BP is a tumor suppressor, and up-regulation of its activity is a goal of interest for cancer therapy. A recently discovered small molecule, eIF4E/eIF4G interaction inhibitor 1 (4EGI-1), disrupts the eIF4E/eIF4G interaction and promotes binding of 4E-BP1 to eIF4E. Structures of 14- to 16-residue 4E-BP fragments bound to eIF4E contain the eIF4E consensus binding motif, (54)YXXXXLΦ(60) (motif 1) but lack known phosphorylation sites. We report here a 2.1-Å crystal structure of mouse eIF4E in complex with m(7)GTP and with a fragment of human 4E-BP1, extended C-terminally from the consensus-binding motif (4E-BP150-84). The extension, which includes a proline-turn-helix segment (motif 2) followed by a loop of irregular structure, reveals the location of two phosphorylation sites (S65 and T70). Our major finding is that the C-terminal extension (motif 3) is critical to 4E-BP1-mediated cell cycle arrest and that it partially overlaps with the binding site of 4EGI-1. The binding of 4E-BP1 and 4EGI-1 to eIF4E is therefore not mutually exclusive, and both ligands contribute to shift the equilibrium toward the inhibition of translation initiation.
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Affiliation(s)
- Naotaka Sekiyama
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA 02115
| | - Haribabu Arthanari
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA 02115
| | - Evangelos Papadopoulos
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA 02115
| | - Ricard A Rodriguez-Mias
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA 02115
| | - Gerhard Wagner
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA 02115
| | - Mélissa Léger-Abraham
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA 02115
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145
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Zytek M, Kowalska J, Lukaszewicz M, Wojtczak BA, Zuberek J, Ferenc-Mrozek A, Darzynkiewicz E, Niedzwiecka A, Jemielity J. Towards novel efficient and stable nuclear import signals: synthesis and properties of trimethylguanosine cap analogs modified within the 5',5'-triphosphate bridge. Org Biomol Chem 2015; 12:9184-99. [PMID: 25296894 DOI: 10.1039/c4ob01579g] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
A trimethylguanosine (TMG) cap is present at the 5' end of several small nuclear and nucleolar RNAs. Recently, it has been reported that the TMG cap is a potential nuclear import signal for nucleus-targeting therapeutic nucleic acids and proteins. The import is mediated by recognition of the TMG cap by the snRNA transporting protein, snurportin1. This work describes the synthesis and properties of a series of dinucleotide TMG cap (m3(2,2,7)GpppG) analogs modified in the 5',5'-triphosphate bridge as tools to study TMG cap-dependent biological processes. The bridge was altered at different positions by introducing either bridging (imidodiphosphate, O to NH and methylenebisphosphonate, O to CH2) or non-bridging (phosphorothioate, O to S and boranophosphate, O to BH3) modifications, or by elongation to tetraphosphate. The stability of novel analogs in blood serum was studied to reveal that the α,β-bridging O to NH substitution (m3(2,2,7)GppNHpG) confers the highest resistance. Short RNAs capped with analogs containing α,β-bridging (m3(2,2,7)GppNHpG) or β-non-bridging (m3(2,2,7)GppSpG D2) modifications were resistant to decapping pyrophosphatase, hNudt16. Preliminary studies on binding by human snurportin1 revealed that both O to NH and O to S substitutions support this binding. Due to favorable properties in all three assays, m3(2,2,7)GppNHpG was selected as a promising candidate for further studies on the efficiency of the TMG cap as a nuclear import signal.
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Affiliation(s)
- Malgorzata Zytek
- Division of Biophysics, Institute of Experimental Physics, Faculty of Physics, University of Warsaw, Zwirki i Wigury 93, 02-089 Warsaw, Poland.
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146
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Structural basis and functional analysis of the SARS coronavirus nsp14-nsp10 complex. Proc Natl Acad Sci U S A 2015; 112:9436-41. [PMID: 26159422 DOI: 10.1073/pnas.1508686112] [Citation(s) in RCA: 331] [Impact Index Per Article: 36.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Nonstructural protein 14 (nsp14) of coronaviruses (CoV) is important for viral replication and transcription. The N-terminal exoribonuclease (ExoN) domain plays a proofreading role for prevention of lethal mutagenesis, and the C-terminal domain functions as a (guanine-N7) methyl transferase (N7-MTase) for mRNA capping. The molecular basis of both these functions is unknown. Here, we describe crystal structures of severe acute respiratory syndrome (SARS)-CoV nsp14 in complex with its activator nonstructural protein10 (nsp10) and functional ligands. One molecule of nsp10 interacts with ExoN of nsp14 to stabilize it and stimulate its activity. Although the catalytic core of nsp14 ExoN is reminiscent of proofreading exonucleases, the presence of two zinc fingers sets it apart from homologs. Mutagenesis studies indicate that both these zinc fingers are essential for the function of nsp14. We show that a DEEDh (the five catalytic amino acids) motif drives nucleotide excision. The N7-MTase domain exhibits a noncanonical MTase fold with a rare β-sheet insertion and a peripheral zinc finger. The cap-precursor guanosine-P3-adenosine-5',5'-triphosphate and S-adenosyl methionine bind in proximity in a highly constricted pocket between two β-sheets to accomplish methyl transfer. Our studies provide the first glimpses, to our knowledge, into the architecture of the nsp14-nsp10 complex involved in RNA viral proofreading.
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147
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Liberman N, Gandin V, Svitkin YV, David M, Virgili G, Jaramillo M, Holcik M, Nagar B, Kimchi A, Sonenberg N. DAP5 associates with eIF2β and eIF4AI to promote Internal Ribosome Entry Site driven translation. Nucleic Acids Res 2015; 43:3764-75. [PMID: 25779044 PMCID: PMC4402527 DOI: 10.1093/nar/gkv205] [Citation(s) in RCA: 64] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2014] [Revised: 02/26/2015] [Accepted: 02/27/2015] [Indexed: 12/14/2022] Open
Abstract
Initiation is a highly regulated rate-limiting step of mRNA translation. During cap-dependent translation, the cap-binding protein eIF4E recruits the mRNA to the ribosome. Specific elements in the 5'UTR of some mRNAs referred to as Internal Ribosome Entry Sites (IRESes) allow direct association of the mRNA with the ribosome without the requirement for eIF4E. Cap-independent initiation permits translation of a subset of cellular and viral mRNAs under conditions wherein cap-dependent translation is inhibited, such as stress, mitosis and viral infection. DAP5 is an eIF4G homolog that has been proposed to regulate both cap-dependent and cap-independent translation. Herein, we demonstrate that DAP5 associates with eIF2β and eIF4AI to stimulate IRES-dependent translation of cellular mRNAs. In contrast, DAP5 is dispensable for cap-dependent translation. These findings provide the first mechanistic insights into the function of DAP5 as a selective regulator of cap-independent translation.
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Affiliation(s)
- Noa Liberman
- Department of Molecular Genetics, The Weizmann Institute of Science, Rehovot 7610001, Israel
| | - Valentina Gandin
- Department of Biochemistry, McGill University, Montréal, Québec H3A 1A3, Canada Rosalind and Morris Goodman Cancer Centre, Montréal, Québec H3A 1A3, Canada
| | - Yuri V Svitkin
- Department of Biochemistry, McGill University, Montréal, Québec H3A 1A3, Canada Rosalind and Morris Goodman Cancer Centre, Montréal, Québec H3A 1A3, Canada
| | - Maya David
- Department of Molecular Genetics, The Weizmann Institute of Science, Rehovot 7610001, Israel
| | - Geneviève Virgili
- Department of Biochemistry, McGill University, Montréal, Québec H3A 1A3, Canada Groupe de Recherche Axé sur la Structure des Protéines, Montréal, Québec H3A 1A3, Canada
| | - Maritza Jaramillo
- Department of Biochemistry, McGill University, Montréal, Québec H3A 1A3, Canada Rosalind and Morris Goodman Cancer Centre, Montréal, Québec H3A 1A3, Canada
| | - Martin Holcik
- Apoptosis Research Centre, Children's Hospital of Eastern Ontario Research Institute, Ottawa, Ontario K1N 6N5, Canada
| | - Bhushan Nagar
- Department of Biochemistry, McGill University, Montréal, Québec H3A 1A3, Canada Groupe de Recherche Axé sur la Structure des Protéines, Montréal, Québec H3A 1A3, Canada
| | - Adi Kimchi
- Department of Molecular Genetics, The Weizmann Institute of Science, Rehovot 7610001, Israel
| | - Nahum Sonenberg
- Department of Biochemistry, McGill University, Montréal, Québec H3A 1A3, Canada Rosalind and Morris Goodman Cancer Centre, Montréal, Québec H3A 1A3, Canada
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148
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Pelletier J, Graff J, Ruggero D, Sonenberg N. Targeting the eIF4F translation initiation complex: a critical nexus for cancer development. Cancer Res 2015; 75:250-63. [PMID: 25593033 DOI: 10.1158/0008-5472.can-14-2789] [Citation(s) in RCA: 265] [Impact Index Per Article: 29.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Elevated protein synthesis is an important feature of many cancer cells and often arises as a consequence of increased signaling flux channeled to eukaryotic initiation factor 4F (eIF4F), the key regulator of the mRNA-ribosome recruitment phase of translation initiation. In many cellular and preclinical models of cancer, eIF4F deregulation results in changes in translational efficiency of specific mRNA classes. Importantly, many of these mRNAs code for proteins that potently regulate critical cellular processes, such as cell growth and proliferation, enhanced cell survival and cell migration that ultimately impinge on several hallmarks of cancer, including increased angiogenesis, deregulated growth control, enhanced cellular survival, epithelial-to-mesenchymal transition, invasion, and metastasis. By being positioned as the molecular nexus downstream of key oncogenic signaling pathways (e.g., Ras, PI3K/AKT/TOR, and MYC), eIF4F serves as a direct link between important steps in cancer development and translation initiation. Identification of mRNAs particularly responsive to elevated eIF4F activity that typifies tumorigenesis underscores the critical role of eIF4F in cancer and raises the exciting possibility of developing new-in-class small molecules targeting translation initiation as antineoplastic agents.
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Affiliation(s)
- Jerry Pelletier
- Department of Biochemistry, McGill University, Montreal, Québec, Canada. The Rosalind and Morris Goodman Cancer Research Center, McGill University, Montreal, Québec, Canada. Department of Oncology, McGill University, Montreal, Québec, Canada.
| | - Jeremy Graff
- Lilly Research Laboratories, Eli Lilly and Company, Indianapolis, Indiana
| | - Davide Ruggero
- School of Medicine and Department of Urology, Helen Diller Family Comprehensive Cancer Center, University of California, San Francisco, California
| | - Nahum Sonenberg
- Department of Biochemistry, McGill University, Montreal, Québec, Canada. The Rosalind and Morris Goodman Cancer Research Center, McGill University, Montreal, Québec, Canada
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149
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Kwok CK, Ding Y, Shahid S, Assmann SM, Bevilacqua PC. A stable RNA G-quadruplex within the 5'-UTR of Arabidopsis thaliana ATR mRNA inhibits translation. Biochem J 2015; 467:91-102. [PMID: 25793418 DOI: 10.1042/bj20141063] [Citation(s) in RCA: 59] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
Guanine quadruplex structures (GQSs) play important roles in the regulation of gene expression and cellular processes. Recent studies provide strong evidence for the formation and function of DNA and RNA GQSs in human cells. However, whether GQSs form and are functional in plants remains essentially unexplored. On the basis of circular dichroism (CD)-detected titration, UV-detected melting, in-line probing (ILP) and reporter gene assay studies, we report the first example of a plant RNA GQS that inhibits translation. This GQS is located within the 5'-UTR of the ATAXIA TELANGIECTASIA-MUTATED AND RAD3-RELATED (ATR) mRNA of Arabidopsis thaliana (mouse-ear cress). We show that this GQS is highly stable and is thermodynamically favoured over a competing hairpin structure in the 5'-UTR at physiological K⁺ and Mg²⁺ concentrations. Results from ILP reveal the secondary structure of the RNA and support formation of the GQS in vitro in the context of the complete 5'-UTR. Transient reporter gene assays performed in living plants reveal that the GQS inhibits translation but not transcription, implicating this GQS as a translational repressor in vivo. Our results provide the first complete demonstration of the formation and function of a regulatory RNA GQS in plants and open new avenues to explore potential functional roles of GQS in the plant kingdom.
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Affiliation(s)
- Chun Kit Kwok
- *Department of Chemistry, Pennsylvania State University, University Park, PA 16802, U.S.A
| | - Yiliang Ding
- *Department of Chemistry, Pennsylvania State University, University Park, PA 16802, U.S.A
| | - Saima Shahid
- †Center for RNA Molecular Biology, Pennsylvania State University, University Park, PA 16802, U.S.A
| | - Sarah M Assmann
- †Center for RNA Molecular Biology, Pennsylvania State University, University Park, PA 16802, U.S.A
| | - Philip C Bevilacqua
- *Department of Chemistry, Pennsylvania State University, University Park, PA 16802, U.S.A
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150
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Fraser CS. Quantitative studies of mRNA recruitment to the eukaryotic ribosome. Biochimie 2015; 114:58-71. [PMID: 25742741 DOI: 10.1016/j.biochi.2015.02.017] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2014] [Accepted: 02/20/2015] [Indexed: 12/20/2022]
Abstract
The process of peptide bond synthesis by ribosomes is conserved between species, but the initiation step differs greatly between the three kingdoms of life. This is illustrated by the evolution of roughly an order of magnitude more initiation factor mass found in humans compared with bacteria. Eukaryotic initiation of translation is comprised of a number of sub-steps: (i) recruitment of an mRNA and initiator methionyl-tRNA to the 40S ribosomal subunit; (ii) migration of the 40S subunit along the 5' UTR to locate the initiation codon; and (iii) recruitment of the 60S subunit to form the 80S initiation complex. Although the mechanism and regulation of initiation has been studied for decades, many aspects of the pathway remain unclear. In this review, I will focus discussion on what is known about the mechanism of mRNA selection and its recruitment to the 40S subunit. I will summarize how the 43S preinitiation complex (PIC) is formed and stabilized by interactions between its components. I will discuss what is known about the mechanism of mRNA selection by the eukaryotic initiation factor 4F (eIF4F) complex and how the selected mRNA is recruited to the 43S PIC. The regulation of this process by secondary structure located in the 5' UTR of an mRNA will also be discussed. Finally, I present a possible kinetic model with which to explain the process of mRNA selection and recruitment to the eukaryotic ribosome.
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Affiliation(s)
- Christopher S Fraser
- Department of Molecular and Cellular Biology, College of Biological Sciences, University of California, Davis, CA 95616, USA.
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