51
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Jank T, Belyi Y, Wirth C, Rospert S, Hu Z, Dengjel J, Tzivelekidis T, Andersen GR, Hunte C, Schlosser A, Aktories K. Protein glutaminylation is a yeast-specific posttranslational modification of elongation factor 1A. J Biol Chem 2017; 292:16014-16023. [PMID: 28801462 DOI: 10.1074/jbc.m117.801035] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2017] [Revised: 08/09/2017] [Indexed: 11/06/2022] Open
Abstract
Ribosomal translation factors are fundamental for protein synthesis and highly conserved in all kingdoms of life. The essential eukaryotic elongation factor 1A (eEF1A) delivers aminoacyl tRNAs to the A-site of the translating 80S ribosome. Several studies have revealed that eEF1A is posttranslationally modified. Using MS analysis, site-directed mutagenesis, and X-ray structural data analysis of Saccharomyces cerevisiae eEF1A, we identified a posttranslational modification in which the α amino group of mono-l-glutamine is covalently linked to the side chain of glutamate 45 in eEF1A. The MS analysis suggested that all eEF1A molecules are modified by this glutaminylation and that this posttranslational modification occurs at all stages of yeast growth. The mutational studies revealed that this glutaminylation is not essential for the normal functions of eEF1A in S. cerevisiae However, eEF1A glutaminylation slightly reduced growth under antibiotic-induced translational stress conditions. Moreover, we identified the same posttranslational modification in eEF1A from Schizosaccharomyces pombe but not in various other eukaryotic organisms tested despite strict conservation of the Glu45 residue among these organisms. We therefore conclude that eEF1A glutaminylation is a yeast-specific posttranslational modification that appears to influence protein translation.
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Affiliation(s)
- Thomas Jank
- From the Institute for Experimental and Clinical Pharmacology and Toxicology, Faculty of Medicine, University of Freiburg, 79104 Freiburg, Germany,
| | - Yury Belyi
- the Gamaleya Research Centre, Moscow 123098, Russia.,the Bioclinicum, Moscow 123098, Russia
| | - Christophe Wirth
- the Institute for Biochemistry and Molecular Biology, ZBMZ, Faculty of Medicine, University of Freiburg, 79104 Freiburg, Germany
| | - Sabine Rospert
- the Institute for Biochemistry and Molecular Biology, ZBMZ, Faculty of Medicine, University of Freiburg, 79104 Freiburg, Germany.,the BIOSS Centre for Biological Signalling Studies, University of Freiburg, 79106 Freiburg, Germany
| | - Zehan Hu
- the Department of Dermatology, Faculty of Medicine, University of Freiburg, 79106 Freiburg, Germany.,the Freiburg Institute for Advanced Studies (FRIAS), University of Freiburg, 79104 Freiburg, Germany.,the Department of Biology, University of Fribourg, Chemin du Musée 10, 1700 Fribourg, Switzerland
| | - Jörn Dengjel
- the Department of Dermatology, Faculty of Medicine, University of Freiburg, 79106 Freiburg, Germany.,the Freiburg Institute for Advanced Studies (FRIAS), University of Freiburg, 79104 Freiburg, Germany.,the Department of Biology, University of Fribourg, Chemin du Musée 10, 1700 Fribourg, Switzerland
| | - Tina Tzivelekidis
- From the Institute for Experimental and Clinical Pharmacology and Toxicology, Faculty of Medicine, University of Freiburg, 79104 Freiburg, Germany
| | - Gregers Rom Andersen
- the Department of Molecular Biology and Genetics, Center for Structural Biology, Aarhus University, DK8000 Aarhus, Denmark, and
| | - Carola Hunte
- the Institute for Biochemistry and Molecular Biology, ZBMZ, Faculty of Medicine, University of Freiburg, 79104 Freiburg, Germany.,the BIOSS Centre for Biological Signalling Studies, University of Freiburg, 79106 Freiburg, Germany
| | - Andreas Schlosser
- the Rudolf Virchow Center for Experimental Biomedicine, University of Würzburg, 97080 Würzburg, Germany
| | - Klaus Aktories
- From the Institute for Experimental and Clinical Pharmacology and Toxicology, Faculty of Medicine, University of Freiburg, 79104 Freiburg, Germany, .,the BIOSS Centre for Biological Signalling Studies, University of Freiburg, 79106 Freiburg, Germany.,the Freiburg Institute for Advanced Studies (FRIAS), University of Freiburg, 79104 Freiburg, Germany
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52
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Saenz-Méndez P, Eriksson M, Eriksson LA. Ligand Selectivity between the ADP-Ribosylating Toxins: An Inverse-Docking Study for Multitarget Drug Discovery. ACS OMEGA 2017; 2:1710-1719. [PMID: 30023642 PMCID: PMC6044789 DOI: 10.1021/acsomega.7b00010] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/05/2017] [Accepted: 03/17/2017] [Indexed: 06/02/2023]
Abstract
Bacterial adenosine 5'-diphosphate-ribosylating toxins are encoded by several human pathogens, such as Pseudomonas aeruginosa (exotoxin A (ETA)), Corynebacterium diphtheriae (diphtheria toxin (DT)), and Vibrio cholerae (cholix toxin (CT)). The toxins modify eukaryotic elongation factor 2, an essential human enzyme in protein synthesis, thereby causing cell death. Targeting external virulence factors, such as the above toxins, is a promising alternative for developing new antibiotics, while at the same time avoiding drug resistance. This study aims to establish a reliable computational methodology to find a "silver bullet" able to target all three toxins. Herein, we have undertaken a detailed analysis of the active sites of ETA, DT, and CT, followed by the determination of the most appropriate selection of the size of the docking sphere. Thereafter, we tested two different approaches for normalizing the docking scores and used these to verify the best target (toxin) for each ligand. The results indicate that the methodology is suitable for identifying selective as well as multitoxin inhibitors, further validating the robustness of inverse docking for target-fishing experiments.
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Affiliation(s)
- Patricia Saenz-Méndez
- Department
of Chemistry and Molecular Biology, University
of Gothenburg, 405 30 Göteborg, Sweden
- Computational
Chemistry and Biology Group, Facultad de Química, Universidad de la República, 11800 Montevideo, Uruguay
| | - Martin Eriksson
- Department
of Chemistry and Molecular Biology, University
of Gothenburg, 405 30 Göteborg, Sweden
| | - Leif A. Eriksson
- Department
of Chemistry and Molecular Biology, University
of Gothenburg, 405 30 Göteborg, Sweden
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53
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Denisova E, Heidenreich B, Nagore E, Rachakonda PS, Hosen I, Akrap I, Traves V, García-Casado Z, López-Guerrero JA, Requena C, Sanmartin O, Serra-Guillén C, Llombart B, Guillén C, Ferrando J, Gimeno E, Nordheim A, Hemminki K, Kumar R. Frequent DPH3 promoter mutations in skin cancers. Oncotarget 2016; 6:35922-30. [PMID: 26416425 PMCID: PMC4742151 DOI: 10.18632/oncotarget.5771] [Citation(s) in RCA: 44] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2015] [Accepted: 09/12/2015] [Indexed: 12/24/2022] Open
Abstract
Recent reports suggested frequent occurrence of cancer associated somatic mutations within regulatory elements of the genome. Based on initial exome sequencing of 21 melanomas, we report frequent somatic mutations in skin cancers in a bidirectional promoter of diphthamide biosynthesis 3 (DPH3) and oxidoreductase NAD-binding domain containing 1 (OXNAD1) genes. The UV-signature mutations occurred at sites adjacent and within a binding motif for E-twenty six/ternary complex factors (Ets/TCF), at -8 and -9 bp from DPH3 transcription start site. Follow up screening of 586 different skin lesions showed that the DPH3 promoter mutations were present in melanocytic nevi (2/114; 2%), melanoma (30/304; 10%), basal cell carcinoma of skin (BCC; 57/137; 42%) and squamous cell carcinoma of skin (SCC; 12/31; 39%). Reporter assays carried out in one melanoma cell line for DPH3 and OXNAD1 orientations showed statistically significant increased promoter activity due to -8/-9CC > TT tandem mutations; although, no effect of the mutations on DPH3 and OXNAD1 transcription in tumors was observed. The results from this study show occurrence of frequent somatic non-coding mutations adjacent to a pre-existing binding site for Ets transcription factors within the directional promoter of DPH3 and OXNAD1 genes in three major skin cancers. The detected mutations displayed typical UV signature; however, the functionality of the mutations remains to be determined.
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Affiliation(s)
- Evgeniya Denisova
- Division of Molecular Genetic Epidemiology, German Cancer Research Center, Heidelberg, Germany
| | - Barbara Heidenreich
- Division of Molecular Genetic Epidemiology, German Cancer Research Center, Heidelberg, Germany
| | - Eduardo Nagore
- Department of Dermatology, Instituto Valenciano de Oncologia, Valencia, Spain
| | | | - Ismail Hosen
- Division of Molecular Genetic Epidemiology, German Cancer Research Center, Heidelberg, Germany
| | - Ivana Akrap
- Interfaculty Institute of Cell Biology, Tuebingen University, and IMPRS ("From Molecules to Organisms"), Tuebingen, Germany
| | - Víctor Traves
- Department of Pathology, Instituto Valenciano de Oncologia, Valencia, Spain
| | - Zaida García-Casado
- Laboratory of Molecular Biology, Instituto Valenciano de Oncologia, Valencia, Spain
| | | | - Celia Requena
- Department of Dermatology, Instituto Valenciano de Oncologia, Valencia, Spain
| | - Onofre Sanmartin
- Department of Dermatology, Instituto Valenciano de Oncologia, Valencia, Spain
| | | | - Beatriz Llombart
- Department of Dermatology, Instituto Valenciano de Oncologia, Valencia, Spain
| | - Carlos Guillén
- Department of Dermatology, Instituto Valenciano de Oncologia, Valencia, Spain
| | - Jose Ferrando
- Departments of Pathology & Dermatology, Hospital Arnau de Vilanova, Valencia, Spain
| | - Enrique Gimeno
- Departments of Pathology & Dermatology, Hospital Arnau de Vilanova, Valencia, Spain
| | - Alfred Nordheim
- Interfaculty Institute of Cell Biology, Tuebingen University, and IMPRS ("From Molecules to Organisms"), Tuebingen, Germany.,German Cancer Consortium (DKTK/DKFZ), Heidelberg, Germany
| | - Kari Hemminki
- Division of Molecular Genetic Epidemiology, German Cancer Research Center, Heidelberg, Germany.,Center for Primary Health Care Research, Lund University, Malmö, Sweden
| | - Rajiv Kumar
- Division of Molecular Genetic Epidemiology, German Cancer Research Center, Heidelberg, Germany
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54
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Cbr1 is a Dph3 reductase required for the tRNA wobble uridine modification. Nat Chem Biol 2016; 12:995-997. [PMID: 27694803 PMCID: PMC5110365 DOI: 10.1038/nchembio.2190] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2016] [Accepted: 07/28/2016] [Indexed: 11/28/2022]
Abstract
Diphthamide and the tRNA wobble uridine modifications both require Dph3 (DiPHthamide biosynthesis 3) protein as an electron donor for the iron-sulfur clusters in their biosynthetic enzymes. Here, using a proteomic approach, we identified Saccharomyces cerevisiae cytochrome B5 reductase (Cbr1) as a NADH-dependent reductase for Dph3. The NADH- and Cbr1-dependent reduction of Dph3 may provide a regulatory linkage between cellular metabolic state and protein translation.
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55
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Billod JM, Saenz-Mendez P, Blomberg A, Eriksson LA. Structures, Properties, and Dynamics of Intermediates in eEF2-Diphthamide Biosynthesis. J Chem Inf Model 2016; 56:1776-86. [PMID: 27525663 DOI: 10.1021/acs.jcim.6b00223] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The eukaryotic translation Elongation Factor 2 (eEF2) is an essential enzyme in protein synthesis. eEF2 contains a unique modification of a histidine (His699 in yeast; HIS) into diphthamide (DTA), obtained via 3-amino-3-carboxypropyl (ACP) and diphthine (DTI) intermediates in the biosynthetic pathway. This essential and unique modification is also vulnerable, in that it can be efficiently targeted by NAD(+)-dependent ADP-ribosylase toxins, such as diphtheria toxin (DT). However, none of the intermediates in the biosynthesis path is equally vulnerable against the toxins. This study aims to address the different susceptibility of DTA and its precursors against bacterial toxins. We have herein undertaken a detailed in silico study of the structural features and dynamic motion of different His699 intermediates along the diphthamide synthesis pathway (HIS, ACP, DTI, DTA). The study points out that DTA forms a strong hydrogen bond with an asparagine which might explain the ADP-ribosylation mechanism caused by the diphtheria toxin (DT). Finally, in silico mutagenesis studies were performed on the DTA modified protein, in order to hamper the formation of such a hydrogen bond. The results indicate that the mutant structure might in fact be less susceptible to attack by DT and thereby behave similarly to DTI in this respect.
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Affiliation(s)
- Jean-Marc Billod
- Department of Chemical and Physical Biology, Center for Biological Research, CIB-CSIC , 28040 Madrid, Spain
| | - Patricia Saenz-Mendez
- Computational Chemistry and Biology Group, Facultad de Química, Universidad de la República , 11800 Montevideo, Uruguay
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56
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Abstract
Engineered tumor-targeted anthrax lethal toxin proteins have been shown to strongly suppress growth of solid tumors in mice. These toxins work through the native toxin receptors tumor endothelium marker-8 and capillary morphogenesis protein-2 (CMG2), which, in other contexts, have been described as markers of tumor endothelium. We found that neither receptor is required for tumor growth. We further demonstrate that tumor cells, which are resistant to the toxin when grown in vitro, become highly sensitive when implanted in mice. Using a range of tissue-specific loss-of-function and gain-of-function genetic models, we determined that this in vivo toxin sensitivity requires CMG2 expression on host-derived tumor endothelial cells. Notably, engineered toxins were shown to suppress the proliferation of isolated tumor endothelial cells. Finally, we demonstrate that administering an immunosuppressive regimen allows animals to receive multiple toxin dosages and thereby produces a strong and durable antitumor effect. The ability to give repeated doses of toxins, coupled with the specific targeting of tumor endothelial cells, suggests that our strategy should be efficacious for a wide range of solid tumors.
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57
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Zhang H, Ng MY, Chen Y, Cooperman BS. Kinetics of initiating polypeptide elongation in an IRES-dependent system. eLife 2016; 5. [PMID: 27253065 PMCID: PMC4963199 DOI: 10.7554/elife.13429] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2015] [Accepted: 06/01/2016] [Indexed: 11/13/2022] Open
Abstract
The intergenic IRES of Cricket Paralysis Virus (CrPV-IRES) forms a tight complex with 80S ribosomes capable of initiating the cell-free synthesis of complete proteins in the absence of initiation factors. Such synthesis raises the question of what effect the necessary IRES dissociation from the tRNA binding sites, and ultimately from all of the ribosome, has on the rates of initial peptide elongation steps as nascent peptide is formed. Here we report the first results measuring rates of reaction for the initial cycles of IRES-dependent elongation. Our results demonstrate that 1) the first two cycles of elongation proceed much more slowly than subsequent cycles, 2) these reduced rates arise from slow pseudo-translocation and translocation steps, and 3) the retarding effect of ribosome-bound IRES on protein synthesis is largely overcome following translocation of tripeptidyl-tRNA. Our results also provide a straightforward approach to detailed mechanistic characterization of many aspects of eukaryotic polypeptide elongation.
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Affiliation(s)
- Haibo Zhang
- Department of Chemistry, University of Pennsylvania, Philadelphia, United States
| | - Martin Y Ng
- Department of Chemistry, University of Pennsylvania, Philadelphia, United States
| | - Yuanwei Chen
- Department of Chemistry, University of Pennsylvania, Philadelphia, United States
| | - Barry S Cooperman
- Department of Chemistry, University of Pennsylvania, Philadelphia, United States
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58
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Murray J, Savva CG, Shin BS, Dever TE, Ramakrishnan V, Fernández IS. Structural characterization of ribosome recruitment and translocation by type IV IRES. eLife 2016; 5. [PMID: 27159451 PMCID: PMC4861600 DOI: 10.7554/elife.13567] [Citation(s) in RCA: 68] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2015] [Accepted: 04/04/2016] [Indexed: 12/20/2022] Open
Abstract
Viral mRNA sequences with a type IV IRES are able to initiate translation without any host initiation factors. Initial recruitment of the small ribosomal subunit as well as two translocation steps before the first peptidyl transfer are essential for the initiation of translation by these mRNAs. Using electron cryomicroscopy (cryo-EM) we have structurally characterized at high resolution how the Cricket Paralysis Virus Internal Ribosomal Entry Site (CrPV-IRES) binds the small ribosomal subunit (40S) and the translocation intermediate stabilized by elongation factor 2 (eEF2). The CrPV-IRES restricts the otherwise flexible 40S head to a conformation compatible with binding the large ribosomal subunit (60S). Once the 60S is recruited, the binary CrPV-IRES/80S complex oscillates between canonical and rotated states (Fernández et al., 2014; Koh et al., 2014), as seen for pre-translocation complexes with tRNAs. Elongation factor eEF2 with a GTP analog stabilizes the ribosome-IRES complex in a rotated state with an extra ~3 degrees of rotation. Key residues in domain IV of eEF2 interact with pseudoknot I (PKI) of the CrPV-IRES stabilizing it in a conformation reminiscent of a hybrid tRNA state. The structure explains how diphthamide, a eukaryotic and archaeal specific post-translational modification of a histidine residue of eEF2, is involved in translocation. DOI:http://dx.doi.org/10.7554/eLife.13567.001
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Affiliation(s)
- Jason Murray
- MRC Laboratory of Molecular Biology, Cambridge, United Kingdom.,Laboratory of Gene Regulation and Development, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, United States
| | | | - Byung-Sik Shin
- Laboratory of Gene Regulation and Development, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, United States
| | - Thomas E Dever
- Laboratory of Gene Regulation and Development, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, United States
| | - V Ramakrishnan
- MRC Laboratory of Molecular Biology, Cambridge, United Kingdom
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59
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Loucks CM, Parboosingh JS, Shaheen R, Bernier FP, McLeod DR, Seidahmed MZ, Puffenberger EG, Ober C, Hegele RA, Boycott KM, Alkuraya FS, Innes AM. Matching two independent cohorts validates DPH1 as a gene responsible for autosomal recessive intellectual disability with short stature, craniofacial, and ectodermal anomalies. Hum Mutat 2015. [PMID: 26220823 DOI: 10.1002/humu.22843] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Recently, Alazami et al. (2015) identified 33 putative candidate disease genes for neurogenetic disorders. One such gene was DPH1, in which a homozygous missense mutation was associated with a 3C syndrome-like phenotype in four patients from a single extended family. Here, we report a second homozygous missense variant in DPH1, seen in four members of a founder population, and associated with a phenotype initially reminiscent of Sensenbrenner syndrome. This postpublication "match" validates DPH1 as a gene underlying syndromic intellectual disability with short stature and craniofacial and ectodermal anomalies, reminiscent of, but distinct from, 3C and Sensenbrenner syndromes. This validation took several years after the independent discoveries due to the absence of effective methods for sharing both candidate phenotype and genotype data between investigators. Sharing of data via Web-based anonymous data exchange servers will play an increasingly important role toward more efficient identification of the molecular basis for rare Mendelian disorders.
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Affiliation(s)
- Catrina M Loucks
- Department of Medical Genetics, Cumming School of Medicine, University of Calgary, Calgary, Alberta, Canada
| | - Jillian S Parboosingh
- Department of Medical Genetics, Cumming School of Medicine, University of Calgary, Calgary, Alberta, Canada.,Alberta Children's Hospital Research Institute for Child and Maternal Health, University of Calgary, Calgary, Alberta, Canada
| | - Ranad Shaheen
- Department of Genetics, King Faisal Specialist Hospital and Research Center, Riyhadh, 11211, Saudi Arabia
| | - Francois P Bernier
- Department of Medical Genetics, Cumming School of Medicine, University of Calgary, Calgary, Alberta, Canada.,Alberta Children's Hospital Research Institute for Child and Maternal Health, University of Calgary, Calgary, Alberta, Canada
| | - D Ross McLeod
- Department of Medical Genetics, Cumming School of Medicine, University of Calgary, Calgary, Alberta, Canada
| | | | | | - Carole Ober
- Department of Human Genetics, and Department of Obstetrics and Gynecology, The University of Chicago, Chicago, Illinois
| | - Robert A Hegele
- Department of Paediatrics, University of Western Ontario, London, Ontario, Canada
| | - Kym M Boycott
- Department of Genetics, Children's Hospital of Eastern Ontario, Ottawa, Ontario, Canada
| | - Fowzan S Alkuraya
- Department of Genetics, King Faisal Specialist Hospital and Research Center, Riyhadh, 11211, Saudi Arabia.,Department of Anatomy and Cell Biology, College of Medicine, Alfaisal University, Riyadh, 11533, Saudi Arabia.,Saudi Human Genome Program, King Abdulaziz City for Science and Technology, Riyadh, 11442, Saudi Arabia
| | - A Micheil Innes
- Department of Medical Genetics, Cumming School of Medicine, University of Calgary, Calgary, Alberta, Canada.,Alberta Children's Hospital Research Institute for Child and Maternal Health, University of Calgary, Calgary, Alberta, Canada
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60
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Loss of diphthamide pre-activates NF-κB and death receptor pathways and renders MCF7 cells hypersensitive to tumor necrosis factor. Proc Natl Acad Sci U S A 2015; 112:10732-7. [PMID: 26261303 DOI: 10.1073/pnas.1512863112] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The diphthamide on human eukaryotic translation elongation factor 2 (eEF2) is the target of ADP ribosylating diphtheria toxin (DT) and Pseudomonas exotoxin A (PE). This modification is synthesized by seven dipthamide biosynthesis proteins (DPH1-DPH7) and is conserved among eukaryotes and archaea. We generated MCF7 breast cancer cell line-derived DPH gene knockout (ko) cells to assess the impact of complete or partial inactivation on diphthamide synthesis and toxin sensitivity, and to address the biological consequence of diphthamide deficiency. Cells with heterozygous gene inactivation still contained predominantly diphthamide-modified eEF2 and were as sensitive to PE and DT as parent cells. Thus, DPH gene copy number reduction does not affect overall diphthamide synthesis and toxin sensitivity. Complete inactivation of DPH1, DPH2, DPH4, and DPH5 generated viable cells without diphthamide. DPH1ko, DPH2ko, and DPH4ko harbored unmodified eEF2 and DPH5ko ACP- (diphthine-precursor) modified eEF2. Loss of diphthamide prevented ADP ribosylation of eEF2, rendered cells resistant to PE and DT, but does not affect sensitivity toward other protein synthesis inhibitors, such as saporin or cycloheximide. Surprisingly, cells without diphthamide (independent of which the DPH gene compromised) were presensitized toward nuclear factor of kappa light polypeptide gene enhancer in B cells (NF-κB) and death-receptor pathways without crossing lethal thresholds. In consequence, loss of diphthamide rendered cells hypersensitive toward TNF-mediated apoptosis. This finding suggests a role of diphthamide in modulating NF-κB, death receptor, or apoptosis pathways.
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61
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He S, Hou X, Xu X, Wan C, Yin P, Liu X, Chen Y, Shu B, Liu F, Xu J. Quantitative proteomic analysis reveals heat stress-induced injury in rat small intestine via activation of the MAPK and NF-κB signaling pathways. MOLECULAR BIOSYSTEMS 2015; 11:826-34. [DOI: 10.1039/c4mb00495g] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
We employed comparative proteomics to reveal a heat stress-induced injury mechanism in rat small intestine.
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62
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Schaffrath R, Abdel-Fattah W, Klassen R, Stark MJR. The diphthamide modification pathway from Saccharomyces cerevisiae--revisited. Mol Microbiol 2014; 94:1213-26. [PMID: 25352115 DOI: 10.1111/mmi.12845] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/27/2014] [Indexed: 01/09/2023]
Abstract
Diphthamide is a conserved modification in archaeal and eukaryal translation elongation factor 2 (EF2). Its name refers to the target function for diphtheria toxin, the disease-causing agent that, through ADP ribosylation of diphthamide, causes irreversible inactivation of EF2 and cell death. Although this clearly emphasizes a pathobiological role for diphthamide, its physiological function is unclear, and precisely why cells need EF2 to contain diphthamide is hardly understood. Nonetheless, the conservation of diphthamide biosynthesis together with syndromes (i.e. ribosomal frame-shifting, embryonic lethality, neurodegeneration and cancer) typical of mutant cells that cannot make it strongly suggests that diphthamide-modified EF2 occupies an important and translation-related role in cell proliferation and development. Whether this is structural and/or regulatory remains to be seen. However, recent progress in dissecting the diphthamide gene network (DPH1-DPH7) from the budding yeast Saccharomyces cerevisiae has significantly advanced our understanding of the mechanisms required to initiate and complete diphthamide synthesis on EF2. Here, we review recent developments in the field that not only have provided novel, previously overlooked and unexpected insights into the pathway and the biochemical players required for diphthamide synthesis but also are likely to foster innovative studies into the potential regulation of diphthamide, and importantly, its ill-defined biological role.
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Affiliation(s)
- Raffael Schaffrath
- Department of Genetics, University of Leicester, Leicester, LE1 7RH, UK; Institut für Biologie, Abteilung Mikrobiologie, Universität Kassel, 34132, Kassel, Germany
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63
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Simon NC, Aktories K, Barbieri JT. Novel bacterial ADP-ribosylating toxins: structure and function. Nat Rev Microbiol 2014; 12:599-611. [PMID: 25023120 PMCID: PMC5846498 DOI: 10.1038/nrmicro3310] [Citation(s) in RCA: 148] [Impact Index Per Article: 14.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Bacterial ADP-ribosyltransferase toxins (bARTTs) transfer ADP-ribose to eukaryotic proteins to promote bacterial pathogenesis. In this Review, we use prototype bARTTs, such as diphtheria toxin and pertussis toxin, as references for the characterization of several new bARTTs from human, insect and plant pathogens, which were recently identified by bioinformatic analyses. Several of these toxins, including cholix toxin (ChxA) from Vibrio cholerae, SpyA from Streptococcus pyogenes, HopU1 from Pseudomonas syringae and the Tcc toxins from Photorhabdus luminescens, ADP-ribosylate novel substrates and have unique organizations, which distinguish them from the reference toxins. The characterization of these toxins increases our appreciation of the range of structural and functional properties that are possessed by bARTTs and their roles in bacterial pathogenesis.
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Affiliation(s)
- Nathan C. Simon
- Medical College of Wisconsin, Microbiology and Molecular Genetics, Milwaukee, WI, USA
| | - Klaus Aktories
- Institute of Experimental and Clinical Pharmacology and Toxicology; Albert-Ludwigs-University Freiburg; Freiburg, Germany
| | - Joseph T. Barbieri
- Medical College of Wisconsin, Microbiology and Molecular Genetics, Milwaukee, WI, USA
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64
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Yu YR, You LR, Yan YT, Chen CM. Role of OVCA1/DPH1 in craniofacial abnormalities of Miller–Dieker syndrome. Hum Mol Genet 2014; 23:5579-96. [DOI: 10.1093/hmg/ddu273] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
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65
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Lin Z, Su X, Chen W, Ci B, Zhang S, Lin H. Dph7 catalyzes a previously unknown demethylation step in diphthamide biosynthesis. J Am Chem Soc 2014; 136:6179-82. [PMID: 24739148 PMCID: PMC4015618 DOI: 10.1021/ja5009272] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
Present on archaeal and eukaryotic translation elongation factor 2, diphthamide represents one of the most intriguing post-translational modifications on proteins. The biosynthesis of diphthamide was proposed to occur in three steps requiring seven proteins, Dph1-7, in eukaryotes. The functional assignments of Dph1-5 in the first and second step have been well established. Recent studies suggest that Dph6 (yeast YLR143W or human ATPBD4) and Dph7 (yeast YBR246W or human WDR85) are involved in the last amidation step, with Dph6 being the actual diphthamide synthetase catalyzing the ATP-dependent amidation reaction. However, the exact molecular role of Dph7 is unclear. Here we demonstrate that Dph7 is an enzyme catalyzing a previously unknown step in the diphthamide biosynthesis pathway. This step is between the Dph5- and Dph6-catalyzed reactions. We demonstrate that the Dph5-catalyzed reaction generates methylated diphthine, a previously overlooked intermediate, and Dph7 is a methylesterase that hydrolyzes methylated diphthine to produce diphthine and allows the Dph6-catalyzed amidation reaction to occur. Thus, our study characterizes the molecular function of Dph7 for the first time and provides a revised diphthamide biosynthesis pathway.
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Affiliation(s)
- Zhewang Lin
- Department of Chemistry and Chemical Biology and ‡Proteomics and Mass Spectrometry Core Facility, Cornell University , Ithaca, New York 14853, United States
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Dong M, Su X, Dzikovski B, Dando EE, Zhu X, Du J, Freed JH, Lin H. Dph3 is an electron donor for Dph1-Dph2 in the first step of eukaryotic diphthamide biosynthesis. J Am Chem Soc 2014; 136:1754-7. [PMID: 24422557 PMCID: PMC3985478 DOI: 10.1021/ja4118957] [Citation(s) in RCA: 57] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
Diphthamide, the target of diphtheria toxin, is a unique posttranslational modification on translation elongation factor 2 (EF2) in archaea and eukaryotes. The biosynthesis of diphthamide was proposed to involve three steps. The first step is the transfer of the 3-amino-3-carboxypropyl group from S-adenosyl-l-methionine (SAM) to the histidine residue of EF2, forming a C-C bond. Previous genetic studies showed this step requires four proteins in eukaryotes, Dph1-Dph4. However, the exact molecular functions for the four proteins are unknown. Previous study showed that Pyrococcus horikoshii Dph2 (PhDph2), a novel iron-sulfur cluster-containing enzyme, forms a homodimer and is sufficient for the first step of diphthamide biosynthesis in vitro. Here we demonstrate by in vitro reconstitution that yeast Dph1 and Dph2 form a complex (Dph1-Dph2) that is equivalent to the homodimer of PhDph2 and is sufficient to catalyze the first step in vitro in the presence of dithionite as the reductant. We further demonstrate that yeast Dph3 (also known as KTI11), a CSL-type zinc finger protein, can bind iron and in the reduced state can serve as an electron donor to reduce the Fe-S cluster in Dph1-Dph2. Our study thus firmly establishes the functions for three of the proteins involved in eukaryotic diphthamide biosynthesis. For most radical SAM enzymes in bacteria, flavodoxins and flavodoxin reductases are believed to serve as electron donors for the Fe-S clusters. The finding that Dph3 is an electron donor for the Fe-S clusters in Dph1-Dph2 is thus interesting and opens up new avenues of research on electron transfer to Fe-S proteins in eukaryotic cells.
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Affiliation(s)
- Min Dong
- Department of Chemistry and Chemical Biology, Cornell University , Ithaca, New York 14853, United States
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Abstract
Eukaryotic and archaeal elongation factor 2 contains a unique post-translationally modified histidine residue, named diphthamide. Genetic and biochemical studies have revealed that diphthamide biosynthesis involves a multi-step pathway that is evolutionally conserved among lower and higher eukaryotes. During certain bacterial infections, diphthamide is specifically recognized by bacterial toxins, including diphtheria toxin, Pseudomonas exotoxin A and cholix toxin. Although the pathological relevance is well studied, the physiological function of diphthamide is still poorly understood. Recently, many new interesting developments in understanding the biosynthesis have been reported. Here, we review the current understanding of the biosynthesis and biological function of diphthamide.
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Affiliation(s)
- Xiaoyang Su
- Department of Chemistry and Chemical Biology, Cornell University, Ithaca, NY 14850, USA
| | - Zhewang Lin
- Department of Chemistry and Chemical Biology, Cornell University, Ithaca, NY 14850, USA
| | - Hening Lin
- Department of Chemistry and Chemical Biology, Cornell University, Ithaca, NY 14850, USA
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Key tissue targets responsible for anthrax-toxin-induced lethality. Nature 2013; 501:63-8. [PMID: 23995686 DOI: 10.1038/nature12510] [Citation(s) in RCA: 82] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2013] [Accepted: 07/31/2013] [Indexed: 02/01/2023]
Abstract
Bacillus anthracis, the causative agent of anthrax disease, is lethal owing to the actions of two exotoxins: anthrax lethal toxin (LT) and oedema toxin (ET). The key tissue targets responsible for the lethal effects of these toxins are unknown. Here we generated cell-type-specific anthrax toxin receptor capillary morphogenesis protein-2 (CMG2)-null mice and cell-type-specific CMG2-expressing mice and challenged them with the toxins. Our results show that lethality induced by LT and ET occurs through damage to distinct cell types; whereas targeting cardiomyocytes and vascular smooth muscle cells is required for LT-induced mortality, ET-induced lethality occurs mainly through its action in hepatocytes. Notably, and in contradiction to what has been previously postulated, targeting of endothelial cells by either toxin does not seem to contribute significantly to lethality. Our findings demonstrate that B. anthracis has evolved to use LT and ET to induce host lethality by coordinately damaging two distinct vital systems.
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Mateyak MK, Kinzy TG. ADP-ribosylation of translation elongation factor 2 by diphtheria toxin in yeast inhibits translation and cell separation. J Biol Chem 2013; 288:24647-55. [PMID: 23853096 DOI: 10.1074/jbc.m113.488783] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Eukaryotic translation elongation factor 2 (eEF2) facilitates the movement of the peptidyl tRNA-mRNA complex from the A site of the ribosome to the P site during protein synthesis. ADP-ribosylation (ADP(R)) of eEF2 by bacterial toxins on a unique diphthamide residue inhibits its translocation activity, but the mechanism is unclear. We have employed a hormone-inducible diphtheria toxin (DT) expression system in Saccharomyces cerevisiae which allows for the rapid induction of ADP(R)-eEF2 to examine the effects of DT in vivo. ADP(R) of eEF2 resulted in a decrease in total protein synthesis consistent with a defect in translation elongation. Association of eEF2 with polyribosomes, however, was unchanged upon expression of DT. Upon prolonged exposure to DT, cells with an abnormal morphology and increased DNA content accumulated. This observation was specific to DT expression and was not observed when translation elongation was inhibited by other methods. Examination of these cells by electron microscopy indicated a defect in cell separation following mitosis. These results suggest that expression of proteins late in the cell cycle is particularly sensitive to inhibition by ADP(R)-eEF2.
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Affiliation(s)
- Maria K Mateyak
- Department of Biochemistry and Molecular Biology, Robert Wood Johnson Medical School, Rutgers, The State University of New Jersey, Piscataway, New Jersey 08854, USA
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Menni C, Kastenmüller G, Petersen AK, Bell JT, Psatha M, Tsai PC, Gieger C, Schulz H, Erte I, John S, Brosnan MJ, Wilson SG, Tsaprouni L, Lim EM, Stuckey B, Deloukas P, Mohney R, Suhre K, Spector TD, Valdes AM. Metabolomic markers reveal novel pathways of ageing and early development in human populations. Int J Epidemiol 2013; 42:1111-9. [PMID: 23838602 PMCID: PMC3781000 DOI: 10.1093/ije/dyt094] [Citation(s) in RCA: 186] [Impact Index Per Article: 16.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
BACKGROUND Human ageing is a complex, multifactorial process and early developmental factors affect health outcomes in old age. METHODS Metabolomic profiling on fasting blood was carried out in 6055 individuals from the UK. Stepwise regression was performed to identify a panel of independent metabolites which could be used as a surrogate for age. We also investigated the association with birthweight overall and within identical discordant twins and with genome-wide methylation levels. RESULTS We identified a panel of 22 metabolites which combined are strongly correlated with age (R(2) = 59%) and with age-related clinical traits independently of age. One particular metabolite, C-glycosyl tryptophan (C-glyTrp), correlated strongly with age (beta = 0.03, SE = 0.001, P = 7.0 × 10(-157)) and lung function (FEV1 beta = -0.04, SE = 0.008, P = 1.8 × 10(-8) adjusted for age and confounders) and was replicated in an independent population (n = 887). C-glyTrp was also associated with bone mineral density (beta = -0.01, SE = 0.002, P = 1.9 × 10(-6)) and birthweight (beta = -0.06, SE = 0.01, P = 2.5 × 10(-9)). The difference in C-glyTrp levels explained 9.4% of the variance in the difference in birthweight between monozygotic twins. An epigenome-wide association study in 172 individuals identified three CpG-sites, associated with levels of C-glyTrp (P < 2 × 10(-6)). We replicated one CpG site in the promoter of the WDR85 gene in an independent sample of 350 individuals (beta = -0.20, SE = 0.04, P = 2.9 × 10(-8)). WDR85 is a regulator of translation elongation factor 2, essential for protein synthesis in eukaryotes. CONCLUSIONS Our data illustrate how metabolomic profiling linked with epigenetic studies can identify some key molecular mechanisms potentially determined in early development that produce long-term physiological changes influencing human health and ageing.
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Affiliation(s)
- Cristina Menni
- Department of Twin Research & Genetic Epidemiology, King's College London, London, UK, Institute of Bioinformatics and Systems Biology, Helmholtz Zentrum München, Neuherberg, Germany, Institute of Genetic Epidemiology, Helmholtz Zentrum München, Neuherberg, Germany, Institute of Epidemiology I, Helmholtz Zentrum München, Neuherberg, Germany, Pfizer Research Laboratories, Groton, CT, USA, Worldwide R&D, Pfizer Inc., Cambridge, MA, USA, School of Medicine and Pharmacology, University of Western Australia, Crawley, WA, Australia, Department of Endocrinology and Diabetes, Sir Charles Gairdner Hospital, Nedlands, WA, Australia, Wellcome Trust Sanger Institute, Hinxton, Cambridge, UK, Metabolon Inc., 617 Davis Drive, Durham, NC 27713, USA; Department of Physiology and Biophysics, Weill Cornell Medical College in Qatar, Education City, Qatar Foundation, Doha, State of Qatar and Academic Rheumatology, University of Nottingham, Nottingham City Hospital, Nottingham, UK
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The amidation step of diphthamide biosynthesis in yeast requires DPH6, a gene identified through mining the DPH1-DPH5 interaction network. PLoS Genet 2013; 9:e1003334. [PMID: 23468660 PMCID: PMC3585130 DOI: 10.1371/journal.pgen.1003334] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2012] [Accepted: 01/07/2013] [Indexed: 01/31/2023] Open
Abstract
Diphthamide is a highly modified histidine residue in eukaryal translation elongation factor 2 (eEF2) that is the target for irreversible ADP ribosylation by diphtheria toxin (DT). In Saccharomyces cerevisiae, the initial steps of diphthamide biosynthesis are well characterized and require the DPH1-DPH5 genes. However, the last pathway step—amidation of the intermediate diphthine to diphthamide—is ill-defined. Here we mine the genetic interaction landscapes of DPH1-DPH5 to identify a candidate gene for the elusive amidase (YLR143w/DPH6) and confirm involvement of a second gene (YBR246w/DPH7) in the amidation step. Like dph1-dph5, dph6 and dph7 mutants maintain eEF2 forms that evade inhibition by DT and sordarin, a diphthamide-dependent antifungal. Moreover, mass spectrometry shows that dph6 and dph7 mutants specifically accumulate diphthine-modified eEF2, demonstrating failure to complete the final amidation step. Consistent with an expected requirement for ATP in diphthine amidation, Dph6 contains an essential adenine nucleotide hydrolase domain and binds to eEF2. Dph6 is therefore a candidate for the elusive amidase, while Dph7 apparently couples diphthine synthase (Dph5) to diphthine amidation. The latter conclusion is based on our observation that dph7 mutants show drastically upregulated interaction between Dph5 and eEF2, indicating that their association is kept in check by Dph7. Physiologically, completion of diphthamide synthesis is required for optimal translational accuracy and cell growth, as indicated by shared traits among the dph mutants including increased ribosomal −1 frameshifting and altered responses to translation inhibitors. Through identification of Dph6 and Dph7 as components required for the amidation step of the diphthamide pathway, our work paves the way for a detailed mechanistic understanding of diphthamide formation. Diphthamide is an unusual modified amino acid found uniquely in a single protein, eEF2, which is required for cells to synthesize new proteins. The name refers to its target function for eEF2 inactivation by diphtheria toxin, the disease-inducing agent produced by the pathogen Corynebacterium diphtheriae. Why cells require eEF2 to contain diphthamide is unclear, although mice unable to make it fail to complete embryogenesis. Cells generate diphthamide by modifying a specific histidine residue in eEF2 using a three-step biosynthetic pathway, the first two steps of which are well defined. However, the enzyme(s) involved in the final amidation step are unknown. Here we integrate genomic and molecular approaches to identify a candidate for the elusive amidase (Dph6) and confirm involvement of a second protein (Dph7) in the amidation step, showing that failure to synthesize diphthamide affects the accuracy of protein synthesis. In contrast to Dph6, however, Dph7 may be regulatory. Our data strongly suggest that it promotes dissociation of eEF2 from diphthine synthase (Dph5), which carries out the second step of diphthamide synthesis, and that Dph5 has a novel role as an eEF2 inhibitor when diphthamide synthesis is incomplete.
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Mittal N, Subramanian G, Bütikofer P, Madhubala R. Unique posttranslational modifications in eukaryotic translation factors and their roles in protozoan parasite viability and pathogenesis. Mol Biochem Parasitol 2013; 187:21-31. [PMID: 23201129 DOI: 10.1016/j.molbiopara.2012.11.001] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2012] [Revised: 11/04/2012] [Accepted: 11/05/2012] [Indexed: 11/21/2022]
Abstract
Protozoan parasites are one of the major causes of diseases worldwide. The vector transmitted parasites exhibit complex life cycles involving interactions between humans, protozoa, and arthropods. In order to adapt themselves to the changing microenvironments, they have to undergo complex morphological and metabolic changes. These changes can be brought about by expressing a new pool of proteins in the cell or by modifying the existing repertoire of proteins via posttranslational modifications (PTMs). PTMs involve covalent modification and processing of proteins thereby modulating their functions. Some of these changes may involve PTMs of parasite proteins to help the parasite survive within the host and the vector. Out of many PTMs known, three are unique since they occur only on single proteins: ethanolamine phosphoglycerol (EPG) glutamate, hypusine and diphthamide. These modifications occur on eukaryotic elongation factor 1A (eEF1A), eukaryotic initiation factor 5A (eIF5A) and eukaryotic elongation factor 2 (eEF2), respectively. Interestingly, the proteins carrying these unique modifications are all involved in the elongation steps of translation. Here we review these unique PTMs, which are well conserved in protozoan parasites, and discuss their roles in viability and pathogenesis of parasites. Characterization of these modifications and studying their roles in physiology as well as pathogenesis will provide new insights in parasite biology, which may also help in developing new therapeutic interventions.
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Affiliation(s)
- Nimisha Mittal
- School of Life Sciences, Jawaharlal Nehru University, New Delhi, India
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The receptors that mediate the direct lethality of anthrax toxin. Toxins (Basel) 2012; 5:1-8. [PMID: 23271637 PMCID: PMC3564063 DOI: 10.3390/toxins5010001] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2012] [Revised: 12/19/2012] [Accepted: 12/21/2012] [Indexed: 11/16/2022] Open
Abstract
Tumor endothelium marker-8 (TEM8) and capillary morphogenesis protein-2 (CMG2) are the two well-characterized anthrax toxin receptors, each containing a von Willebrand factor A (vWA) domain responsible for anthrax protective antigen (PA) binding. Recently, a cell-based analysis was used to implicate another vWA domain-containing protein, integrin β1 as a third anthrax toxin receptor. To explore whether proteins other than TEM8 and CMG2 function as anthrax toxin receptors in vivo, we challenged mice lacking TEM8 and/or CMG2. Specifically, we used as an effector protein the fusion protein FP59, a fusion between the PA-binding domain of anthrax lethal factor (LF) and the catalytic domain of Pseudomonas aeruginosa exotoxin A. FP59 is at least 50-fold more potent than LF in the presence of PA, with 2 μg PA + 2 μg FP59 being sufficient to kill a mouse. While TEM8(-/-) and wild type control mice succumbed to a 5 μg PA + 5 μg FP59 challenge, CMG2(-/-) mice were completely resistant to this dose, confirming that CMG2 is the major anthrax toxin receptor in vivo. To detect whether any toxic effects are mediated by TEM8 or other putative receptors such as integrin β1, CMG2(-/-)/TEM8(-/-) mice were challenged with as many as five doses of 50 μg PA + 50 μg FP59. Strikingly, the CMG2(-/-)/TEM8(-/-) mice were completely resistant to the 5-dose challenge. These results strongly suggest that TEM8 is the only minor anthrax toxin receptor mediating direct lethality in vivo and that other proteins implicated as receptors do not play this role.
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Chemogenomic approach identified yeast YLR143W as diphthamide synthetase. Proc Natl Acad Sci U S A 2012; 109:19983-7. [PMID: 23169644 DOI: 10.1073/pnas.1214346109] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Abstract
Many genes are of unknown functions in any sequenced genome. A combination of chemical and genetic perturbations has been used to investigate gene functions. Here we present a case that such "chemogenomics" information can be effectively used to identify missing genes in a defined biological pathway. In particular, we identified the previously unknown enzyme diphthamide synthetase for the last step of diphthamide biosynthesis. We found that yeast protein YLR143W is the diphthamide synthetase catalyzing the last amidation step using ammonium and ATP. Diphthamide synthetase is evolutionarily conserved in eukaryotes. The previously uncharacterized human gene ATPBD4 is the ortholog of yeast YLR143W and fully rescues the deletion of YLR143W in yeast.
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