1
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Verma AK, Sharma P, Islam Z, Biswal AK, Tak Y, Sahi C. Arabidopsis Dph4 is an Hsp70 Cochaperone with Iron-Binding Properties. ACS OMEGA 2024; 9:37650-37661. [PMID: 39281955 PMCID: PMC11391554 DOI: 10.1021/acsomega.4c01776] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/23/2024] [Revised: 07/06/2024] [Accepted: 07/30/2024] [Indexed: 09/18/2024]
Abstract
J-domain proteins (JDPs) are obligate cochaperones of Hsp70s with a wide range of functions in protein homeostasis. Although the J-domain is required for the stimulation of Hsp70s ATPase activity, the functional specificity of JDPs is governed by domains or regions other than the J-domain. Jjj3/Dph4, a class III JDP, is required for diphthamide (DPH) biosynthesis in eukaryotes, including yeast and mammals. Dph4 has a conserved N-terminal J-domain and an uncharacterized C-terminal domain containing a signature CSL zinc finger motif. Previously, we showed that the Dph4 ortholog in Arabidopsis thaliana (atDjC13/AtJjj3/AtDph4) could restore DPH biosynthesis in yeast jjj3Δ mutant in a J-domain-dependent manner. Here, we characterize the C-terminal CSL motif of AtDph4 using yeast genetic and biochemical approaches. The CSL motif of AtDph4 is essential for DPH biosynthesis, and like human Dph4, AtDph4 showed distinct iron-binding activity, which is not present in its yeast counterpart. ScDph4 and AtDph4 proteins exhibit distinct iron-binding capabilities, as evidenced by UV-vis spectrophotometry, SEM-EDS (energy-dispersive spectroscopy function on the scanning electron microscope) and electron paramagnetic resonance (EPR) spectra analyses. Collectively, our data suggests that beyond their role as an Hsp70 cochaperone, Dph4 homologues in complex eukaryotes may have iron-binding abilities, indicating a potential role in iron-sulfur cluster assembly and iron homeostasis.
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Affiliation(s)
- Amit Kumar Verma
- Department of Biological Sciences, Indian Institute of Science Education and Research, Bhopal, Madhya Pradesh 462066, India
- Department of Internal Medicine, UT Southwestern Medical Center, Dallas, Texas 75390-9096, United States
| | - Priya Sharma
- Department of Botany, Faculty of Science, University of Delhi, Delhi 110007, India
| | - Zeyaul Islam
- Department of Biological Sciences, Indian Institute of Science Education and Research, Bhopal, Madhya Pradesh 462066, India
- Diabetes Research Center (DRC), Qatar Biomedical Research Institute (QBRI), Hamad Bin Khalifa University (HBKU), Qatar Foundation, PO Box 34110 Doha, Qatar
| | - Anup Kumar Biswal
- Department of Biological Sciences, Indian Institute of Science Education and Research, Bhopal, Madhya Pradesh 462066, India
| | - Yogesh Tak
- Center for Alzheimer's and Neurodegenerative Diseases, Peter O'Donnell Jr. Brian Institute, UT Southwestern Medical Center, Dallas, Texas 75390-9096, United States
| | - Chandan Sahi
- Department of Biological Sciences, Indian Institute of Science Education and Research, Bhopal, Madhya Pradesh 462066, India
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2
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Shi Y, Huang D, Song C, Cao R, Wang Z, Wang D, Zhao L, Xu X, Lu C, Xiong F, Zhao H, Li S, Zhou Q, Luo S, Hu D, Zhang Y, Wang C, Shen Y, Su W, Wu Y, Schmitz K, Wei S, Song W. Diphthamide deficiency promotes association of eEF2 with p53 to induce p21 expression and neural crest defects. Nat Commun 2024; 15:3301. [PMID: 38671004 PMCID: PMC11053169 DOI: 10.1038/s41467-024-47670-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2022] [Accepted: 04/08/2024] [Indexed: 04/28/2024] Open
Abstract
Diphthamide is a modified histidine residue unique for eukaryotic translation elongation factor 2 (eEF2), a key ribosomal protein. Loss of this evolutionarily conserved modification causes developmental defects through unknown mechanisms. In a patient with compound heterozygous mutations in Diphthamide Biosynthesis 1 (DPH1) and impaired eEF2 diphthamide modification, we observe multiple defects in neural crest (NC)-derived tissues. Knockin mice harboring the patient's mutations and Xenopus embryos with Dph1 depleted also display NC defects, which can be attributed to reduced proliferation in the neuroepithelium. DPH1 depletion facilitates dissociation of eEF2 from ribosomes and association with p53 to promote transcription of the cell cycle inhibitor p21, resulting in inhibited proliferation. Knockout of one p21 allele rescues the NC phenotypes in the knockin mice carrying the patient's mutations. These findings uncover an unexpected role for eEF2 as a transcriptional coactivator for p53 to induce p21 expression and NC defects, which is regulated by diphthamide modification.
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Affiliation(s)
- Yu Shi
- Department of Clinical Laboratory, Children's Hospital of Chongqing Medical University, Chongqing Key Laboratory of Child Neurodevelopment and Cognitive Disorders, Ministry of Education Key Laboratory of Child Development and Disorders, National Clinical Research Center for Child Health and Disorders, 136 Zhongshan 2nd Rd, Chongqing, 400014, China.
- Department of Biological Sciences, University of Delaware, Newark, DE, 19716, USA.
| | - Daochao Huang
- Department of Pediatric Research Institute, Children's Hospital of Chongqing Medical University, 136 Zhongshan 2nd Rd, Chongqing, 400014, China
| | - Cui Song
- Department of Endocrinology and Genetic Metabolism Disease, Children's Hospital of Chongqing Medical University, 136 Zhongshan 2nd Rd, Chongqing, 400014, China
| | - Ruixue Cao
- Oujiang Laboratory (Zhejiang Lab for Regenerative Medicine, Vision and Brain Health), Institute of Aging, Key Laboratory of Alzheimer's Disease of Zhejiang Province, School of Mental Health and Kangning Hospital, The Second Affiliated Hospital and Yuying Children's Hospital, Wenzhou Medical University, Wenzhou, 325035, Zhejiang, China
| | - Zhao Wang
- Oujiang Laboratory (Zhejiang Lab for Regenerative Medicine, Vision and Brain Health), Institute of Aging, Key Laboratory of Alzheimer's Disease of Zhejiang Province, School of Mental Health and Kangning Hospital, The Second Affiliated Hospital and Yuying Children's Hospital, Wenzhou Medical University, Wenzhou, 325035, Zhejiang, China
| | - Dan Wang
- Department of Pediatric Research Institute, Children's Hospital of Chongqing Medical University, 136 Zhongshan 2nd Rd, Chongqing, 400014, China
| | - Li Zhao
- Department of Pediatric Research Institute, Children's Hospital of Chongqing Medical University, 136 Zhongshan 2nd Rd, Chongqing, 400014, China
| | - Xiaolu Xu
- Department of Biological Sciences, University of Delaware, Newark, DE, 19716, USA
| | - Congyu Lu
- Department of Biological Sciences, University of Delaware, Newark, DE, 19716, USA
| | - Feng Xiong
- Department of Endocrinology and Genetic Metabolism Disease, Children's Hospital of Chongqing Medical University, 136 Zhongshan 2nd Rd, Chongqing, 400014, China
| | - Haowen Zhao
- Department of Clinical Laboratory, Children's Hospital of Chongqing Medical University, Chongqing Key Laboratory of Child Neurodevelopment and Cognitive Disorders, Ministry of Education Key Laboratory of Child Development and Disorders, National Clinical Research Center for Child Health and Disorders, 136 Zhongshan 2nd Rd, Chongqing, 400014, China
- Department of Pediatric Research Institute, Children's Hospital of Chongqing Medical University, 136 Zhongshan 2nd Rd, Chongqing, 400014, China
| | - Shuxiang Li
- Department of Pediatric Research Institute, Children's Hospital of Chongqing Medical University, 136 Zhongshan 2nd Rd, Chongqing, 400014, China
- Department of Endocrinology and Genetic Metabolism Disease, Children's Hospital of Chongqing Medical University, 136 Zhongshan 2nd Rd, Chongqing, 400014, China
| | - Quansheng Zhou
- Department of Pediatric Research Institute, Children's Hospital of Chongqing Medical University, 136 Zhongshan 2nd Rd, Chongqing, 400014, China
- Department of Endocrinology and Genetic Metabolism Disease, Children's Hospital of Chongqing Medical University, 136 Zhongshan 2nd Rd, Chongqing, 400014, China
| | - Shuyue Luo
- Department of Pediatric Research Institute, Children's Hospital of Chongqing Medical University, 136 Zhongshan 2nd Rd, Chongqing, 400014, China
| | - Dongjie Hu
- Department of Pediatric Research Institute, Children's Hospital of Chongqing Medical University, 136 Zhongshan 2nd Rd, Chongqing, 400014, China
| | - Yun Zhang
- Department of Radiology, Children's Hospital of Chongqing Medical University, 136 Zhongshan 2nd Rd, Chongqing, 400014, China
| | - Cui Wang
- Department of Radiology, Children's Hospital of Chongqing Medical University, 136 Zhongshan 2nd Rd, Chongqing, 400014, China
| | - Yiping Shen
- Division of Genetics and Genomics, Boston Children's Hospital and Harvard Medical School, Boston, MA, 02115, USA
| | - Weiting Su
- Kunming Institute of Zoology, Chinese Academy of Science, Kunming, 650223, Yunnan, China
| | - Yili Wu
- Oujiang Laboratory (Zhejiang Lab for Regenerative Medicine, Vision and Brain Health), Institute of Aging, Key Laboratory of Alzheimer's Disease of Zhejiang Province, School of Mental Health and Kangning Hospital, The Second Affiliated Hospital and Yuying Children's Hospital, Wenzhou Medical University, Wenzhou, 325035, Zhejiang, China
| | - Karl Schmitz
- Department of Biological Sciences, University of Delaware, Newark, DE, 19716, USA
| | - Shuo Wei
- Department of Biological Sciences, University of Delaware, Newark, DE, 19716, USA.
| | - Weihong Song
- Oujiang Laboratory (Zhejiang Lab for Regenerative Medicine, Vision and Brain Health), Institute of Aging, Key Laboratory of Alzheimer's Disease of Zhejiang Province, School of Mental Health and Kangning Hospital, The Second Affiliated Hospital and Yuying Children's Hospital, Wenzhou Medical University, Wenzhou, 325035, Zhejiang, China.
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3
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Ütkür K, Mayer K, Liu S, Brinkmann U, Schaffrath R. Functional Integrity of Radical SAM Enzyme Dph1•Dph2 Requires Non-Canonical Cofactor Motifs with Tandem Cysteines. Biomolecules 2024; 14:470. [PMID: 38672486 PMCID: PMC11048331 DOI: 10.3390/biom14040470] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2024] [Revised: 04/05/2024] [Accepted: 04/09/2024] [Indexed: 04/28/2024] Open
Abstract
The Dph1•Dph2 heterodimer from yeast is a radical SAM (RS) enzyme that generates the 3-amino-3-carboxy-propyl (ACP) precursor for diphthamide, a clinically relevant modification on eukaryotic elongation factor 2 (eEF2). ACP formation requires SAM cleavage and atypical Cys-bound Fe-S clusters in each Dph1 and Dph2 subunit. Intriguingly, the first Cys residue in each motif is found next to another ill-defined cysteine that we show is conserved across eukaryotes. As judged from structural modeling, the orientation of these tandem cysteine motifs (TCMs) suggests a candidate Fe-S cluster ligand role. Hence, we generated, by site-directed DPH1 and DPH2 mutagenesis, Dph1•Dph2 variants with cysteines from each TCM replaced individually or in combination by serines. Assays diagnostic for diphthamide formation in vivo reveal that while single substitutions in the TCM of Dph2 cause mild defects, double mutations almost entirely inactivate the RS enzyme. Based on enhanced Dph1 and Dph2 subunit instability in response to cycloheximide chases, the variants with Cys substitutions in their cofactor motifs are particularly prone to protein degradation. In sum, we identify a fourth functionally cooperative Cys residue within the Fe-S motif of Dph2 and show that the Cys-based cofactor binding motifs in Dph1 and Dph2 are critical for the structural integrity of the dimeric RS enzyme in vivo.
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Affiliation(s)
- Koray Ütkür
- Institut für Biologie, Fachgebiet Mikrobiologie, Universität Kassel, 34132 Kassel, Germany;
| | - Klaus Mayer
- Roche Pharma Research and Early Development (pRED), Large Molecule Research, Roche Innovation Center Munich, 82377 Penzberg, Germany; (K.M.); (U.B.)
| | - Shihui Liu
- Division of Infectious Diseases, Department of Medicine, University of Pittsburgh, Pittsburgh, PA 15261, USA;
| | - Ulrich Brinkmann
- Roche Pharma Research and Early Development (pRED), Large Molecule Research, Roche Innovation Center Munich, 82377 Penzberg, Germany; (K.M.); (U.B.)
| | - Raffael Schaffrath
- Institut für Biologie, Fachgebiet Mikrobiologie, Universität Kassel, 34132 Kassel, Germany;
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4
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Schaffrath R, Brinkmann U. Diphthamide - a conserved modification of eEF2 with clinical relevance. Trends Mol Med 2024; 30:164-177. [PMID: 38097404 DOI: 10.1016/j.molmed.2023.11.008] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2023] [Revised: 11/03/2023] [Accepted: 11/09/2023] [Indexed: 02/17/2024]
Abstract
Diphthamide, a complex modification on eukaryotic translation elongation factor 2 (eEF2), assures reading-frame fidelity during translation. Diphthamide and enzymes for its synthesis are conserved in eukaryotes and archaea. Originally identified as target for diphtheria toxin (DT) in humans, its clinical relevance now proves to be broader than the link to pathogenic bacteria. Diphthamide synthesis enzymes (DPH1 and DPH3) are associated with cancer, and DPH gene mutations can cause diphthamide deficiency syndrome (DDS). Finally, new analyses provide evidence that diphthamide may restrict propagation of viruses including SARS-CoV-2 and HIV-1, and that DPH enzymes are targeted by viruses for degradation to overcome this restriction. This review describes how diphthamide is synthesized and functions in translation, and covers its clinical relevance in human development, cancer, and infectious diseases.
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Affiliation(s)
- Raffael Schaffrath
- Institut für Biologie, Fachgebiet Mikrobiologie, Universität Kassel, Kassel, Germany.
| | - Ulrich Brinkmann
- Roche Pharma Research and Early Development (pRED), Large Molecule Research, Roche Innovation Center Munich, Penzberg, Germany.
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5
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Ütkür K, Schmidt S, Mayer K, Klassen R, Brinkmann U, Schaffrath R. DPH1 Gene Mutations Identify a Candidate SAM Pocket in Radical Enzyme Dph1•Dph2 for Diphthamide Synthesis on EF2. Biomolecules 2023; 13:1655. [PMID: 38002337 PMCID: PMC10669111 DOI: 10.3390/biom13111655] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2023] [Revised: 11/10/2023] [Accepted: 11/13/2023] [Indexed: 11/26/2023] Open
Abstract
In eukaryotes, the Dph1•Dph2 dimer is a non-canonical radical SAM enzyme. Using iron-sulfur (FeS) clusters, it cleaves the cosubstrate S-adenosyl-methionine (SAM) to form a 3-amino-3-carboxy-propyl (ACP) radical for the synthesis of diphthamide. The latter decorates a histidine residue on elongation factor 2 (EF2) conserved from archaea to yeast and humans and is important for accurate mRNA translation and protein synthesis. Guided by evidence from archaeal orthologues, we searched for a putative SAM-binding pocket in Dph1•Dph2 from Saccharomyces cerevisiae. We predict an SAM-binding pocket near the FeS cluster domain that is conserved across eukaryotes in Dph1 but not Dph2. Site-directed DPH1 mutagenesis and functional characterization through assay diagnostics for the loss of diphthamide reveal that the SAM pocket is essential for synthesis of the décor on EF2 in vivo. Further evidence from structural modeling suggests particularly critical residues close to the methionine moiety of SAM. Presumably, they facilitate a geometry specific for SAM cleavage and ACP radical formation that distinguishes Dph1•Dph2 from classical radical SAM enzymes, which generate canonical 5'-deoxyadenosyl (dAdo) radicals.
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Affiliation(s)
- Koray Ütkür
- Institut für Biologie, Fachgebiet Mikrobiologie, Universität Kassel, 34132 Kassel, Germany; (K.Ü.); (S.S.); (R.K.)
| | - Sarina Schmidt
- Institut für Biologie, Fachgebiet Mikrobiologie, Universität Kassel, 34132 Kassel, Germany; (K.Ü.); (S.S.); (R.K.)
| | - Klaus Mayer
- Roche Pharma Research and Early Development (pRED), Large Molecule Research, Roche Innovation Center Munich, 82377 Penzberg, Germany; (K.M.); (U.B.)
| | - Roland Klassen
- Institut für Biologie, Fachgebiet Mikrobiologie, Universität Kassel, 34132 Kassel, Germany; (K.Ü.); (S.S.); (R.K.)
| | - Ulrich Brinkmann
- Roche Pharma Research and Early Development (pRED), Large Molecule Research, Roche Innovation Center Munich, 82377 Penzberg, Germany; (K.M.); (U.B.)
| | - Raffael Schaffrath
- Roche Pharma Research and Early Development (pRED), Large Molecule Research, Roche Innovation Center Munich, 82377 Penzberg, Germany; (K.M.); (U.B.)
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6
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Ütkür K, Mayer K, Khan M, Manivannan T, Schaffrath R, Brinkmann U. DPH1 and DPH2 variants that confer susceptibility to diphthamide deficiency syndrome in human cells and yeast models. Dis Model Mech 2023; 16:dmm050207. [PMID: 37675463 PMCID: PMC10538292 DOI: 10.1242/dmm.050207] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2023] [Accepted: 08/21/2023] [Indexed: 09/08/2023] Open
Abstract
The autosomal-recessive diphthamide deficiency syndrome presents as intellectual disability with developmental abnormalities, seizures, craniofacial and additional morphological phenotypes. It is caused by reduced activity of proteins that synthesize diphthamide on human translation elongation factor 2. Diphthamide synthesis requires seven proteins (DPH1-DPH7), with clinical deficiency described for DPH1, DPH2 and DPH5. A limited set of variant alleles from syndromic patients has been functionally analyzed, but databases (gnomAD) list additional so far uncharacterized variants in human DPH1 and DPH2. Because DPH enzymes are conserved among eukaryotes, their functionality can be assessed in yeast and mammalian cells. Our experimental assessment of known and uncharacterized DPH1 and DPH2 missense alleles showed that six variants are tolerated despite inter-species conservation. Ten additional human DPH1 (G113R, A114T, H132P, H132R, S136R, C137F, L138P, Y152C, S221P, H240R) and two DPH2 (H105P, C341Y) variants showed reduced functionality and hence are deficiency-susceptibility alleles. Some variants locate close to the active enzyme center and may affect catalysis, while others may impact on enzyme activation. In sum, our study has identified functionally compromised alleles of DPH1 and DPH2 genes that likely cause diphthamide deficiency syndrome.
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Affiliation(s)
- Koray Ütkür
- Institut für Biologie,Fachgebiet Mikrobiologie, Universität Kassel, 34132 Kassel, Germany
| | - Klaus Mayer
- Roche Pharma Research and Early Development (pRED), Large Molecule Research, Roche Innovation Center Munich, 82377 Penzberg, Germany
| | - Maliha Khan
- Institut für Biologie,Fachgebiet Mikrobiologie, Universität Kassel, 34132 Kassel, Germany
| | - Thirishika Manivannan
- Institut für Biologie,Fachgebiet Mikrobiologie, Universität Kassel, 34132 Kassel, Germany
| | - Raffael Schaffrath
- Institut für Biologie,Fachgebiet Mikrobiologie, Universität Kassel, 34132 Kassel, Germany
| | - Ulrich Brinkmann
- Roche Pharma Research and Early Development (pRED), Large Molecule Research, Roche Innovation Center Munich, 82377 Penzberg, Germany
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7
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Farache D, Antine SP, Lee ASY. Moonlighting translation factors: multifunctionality drives diverse gene regulation. Trends Cell Biol 2022; 32:762-772. [PMID: 35466028 PMCID: PMC9378348 DOI: 10.1016/j.tcb.2022.03.006] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2021] [Revised: 03/16/2022] [Accepted: 03/18/2022] [Indexed: 12/09/2022]
Abstract
Translation factors have traditionally been viewed as proteins that drive ribosome function and ensure accurate mRNA translation. Recent discoveries have highlighted that these factors can also moonlight in gene regulation, but through functions distinct from their canonical roles in protein synthesis. Notably, the additional functions that translation factors encode are diverse, ranging from transcriptional control and extracellular signaling to RNA binding, and are highly regulated in response to external cues and the intrinsic cellular state. Thus, this multifunctionality of translation factors provides an additional mechanism for exquisite control of gene expression.
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Affiliation(s)
- Dorian Farache
- Department of Cell Biology, Harvard Medical School, Boston, MA, USA; Department of Cancer Immunology and Virology, Dana-Farber Cancer Institute, Boston, MA, USA
| | - Sadie P Antine
- Department of Cell Biology, Harvard Medical School, Boston, MA, USA; Department of Cancer Immunology and Virology, Dana-Farber Cancer Institute, Boston, MA, USA
| | - Amy S Y Lee
- Department of Cell Biology, Harvard Medical School, Boston, MA, USA; Department of Cancer Immunology and Virology, Dana-Farber Cancer Institute, Boston, MA, USA.
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8
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Tu WL, Chih YC, Shih YT, Yu YR, You LR, Chen CM. Context-specific roles of diphthamide deficiency in hepatocellular carcinogenesis. J Pathol 2022; 258:149-163. [PMID: 35781884 DOI: 10.1002/path.5986] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2022] [Revised: 06/13/2022] [Accepted: 07/01/2022] [Indexed: 11/07/2022]
Abstract
Diphthamide biosynthesis protein 1 (DPH1) is biochemically involved in the first step of diphthamide biosynthesis, a post-translational modification of eukaryotic elongation factor 2 (EEF2). Earlier studies showed that DPH1, also known as ovarian cancer-associated gene 1 (OVCA1), is involved in ovarian carcinogenesis. However, the role of DPH1 in hepatocellular carcinoma (HCC) remains unclear. To investigate the impact of DPH1 in hepatocellular carcinogenesis, we have performed data mining from The Cancer Genome Atlas Liver Hepatocellular Carcinoma (TCGA-LIHC) dataset. We found that reduced DPH1 levels were associated with advanced stages and poor survival of patients with HCC. Also, we generated hepatocyte-specific Dph1 deficient mice and showed that diphthamide deficient EEF2 resulted in a reduced translation elongation rate in the hepatocytes and let to mild liver damage with fatty accumulation. After N-diethylnitrosamine (DEN) -induced acute liver injury, p53-mediated pericentral hepatocyte death was increased, and compensatory proliferation was reduced in Dph1-deficient mice. Consistent with these effects, Dph1 deficiency decreased the incidence of DEN-induced pericentral-derived HCC and revealed a protective effect against p53 loss. In contrast, Dph1 deficiency combined with Trp53- or Trp53/Pten-deficient hepatocytes led to increased tumor loads associated with KRT19 (K19)-positive periportal-like cell expansion in mice. Further gene set enrichment analysis also revealed that HCC patients with lower levels of DPH1 and TP53 expression had enriched gene-sets related to the cell cycle and K19-upregulated HCC. Additionally, liver tumor organoids obtained from 6-month-old Pten/Trp53/Dph1-triple-mutant mice had a higher frequency of organoid re-initiation cells and higher proliferative index compared with those of the Pten/Trp53-double-mutant. Pten/Trp53/Dph1-triple-mutant liver tumor organoids showed expression of genes associated with stem/progenitor phenotypes, including Krt19 and Prominin-1 (Cd133) progenitor markers, combined with low hepatocyte-expressed fibrinogen genes. These findings indicate that diphthamide deficiency differentially regulates hepatocellular carcinogenesis, which inhibits pericentral hepatocytes-derived tumor and promotes periportal progenitors-associated liver tumors. This article is protected by copyright. All rights reserved.
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Affiliation(s)
- Wei-Ling Tu
- Department of Life Sciences and Institute of Genome Sciences, National Yang Ming, Chiao Tung University, Taipei, Taiwan
| | - Yu-Chan Chih
- Department of Life Sciences and Institute of Genome Sciences, National Yang Ming, Chiao Tung University, Taipei, Taiwan
| | - Ya-Tung Shih
- Department of Life Sciences and Institute of Genome Sciences, National Yang Ming, Chiao Tung University, Taipei, Taiwan
| | - Yi-Ru Yu
- Department of Life Sciences and Institute of Genome Sciences, National Yang Ming, Chiao Tung University, Taipei, Taiwan
| | - Li-Ru You
- Institute of Biochemistry and Molecular Biology, National Yang Ming Chiao Tung University, Taipei, Taiwan.,Cancer Progression Research Center, National Yang Ming Chiao Tung University, Taipei, Taiwan
| | - Chun-Ming Chen
- Department of Life Sciences and Institute of Genome Sciences, National Yang Ming, Chiao Tung University, Taipei, Taiwan.,Cancer Progression Research Center, National Yang Ming Chiao Tung University, Taipei, Taiwan
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9
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Kišonaitė M, Wild K, Lapouge K, Ruppert T, Sinning I. High-resolution structures of a thermophilic eukaryotic 80S ribosome reveal atomistic details of translocation. Nat Commun 2022; 13:476. [PMID: 35079002 PMCID: PMC8789840 DOI: 10.1038/s41467-022-27967-9] [Citation(s) in RCA: 19] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2021] [Accepted: 01/02/2022] [Indexed: 11/09/2022] Open
Abstract
AbstractRibosomes are complex and highly conserved ribonucleoprotein assemblies catalyzing protein biosynthesis in every organism. Here we present high-resolution cryo-EM structures of the 80S ribosome from a thermophilic fungus in two rotational states, which due to increased 80S stability provide a number of mechanistic details of eukaryotic translation. We identify a universally conserved ‘nested base-triple knot’ in the 26S rRNA at the polypeptide tunnel exit with a bulged-out nucleotide that likely serves as an adaptable element for nascent chain containment and handover. We visualize the structure and dynamics of the ribosome protective factor Stm1 upon ribosomal 40S head swiveling. We describe the structural impact of a unique and essential m1acp3 Ψ 18S rRNA hyper-modification embracing the anticodon wobble-position for eukaryotic tRNA and mRNA translocation. We complete the eEF2-GTPase switch cycle describing the GDP-bound post-hydrolysis state. Taken together, our data and their integration into the structural landscape of 80S ribosomes furthers our understanding of protein biogenesis.
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10
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Iron in Translation: From the Beginning to the End. Microorganisms 2021; 9:microorganisms9051058. [PMID: 34068342 PMCID: PMC8153317 DOI: 10.3390/microorganisms9051058] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2021] [Revised: 05/10/2021] [Accepted: 05/11/2021] [Indexed: 12/16/2022] Open
Abstract
Iron is an essential element for all eukaryotes, since it acts as a cofactor for many enzymes involved in basic cellular functions, including translation. While the mammalian iron-regulatory protein/iron-responsive element (IRP/IRE) system arose as one of the first examples of translational regulation in higher eukaryotes, little is known about the contribution of iron itself to the different stages of eukaryotic translation. In the yeast Saccharomyces cerevisiae, iron deficiency provokes a global impairment of translation at the initiation step, which is mediated by the Gcn2-eIF2α pathway, while the post-transcriptional regulator Cth2 specifically represses the translation of a subgroup of iron-related transcripts. In addition, several steps of the translation process depend on iron-containing enzymes, including particular modifications of translation elongation factors and transfer RNAs (tRNAs), and translation termination by the ATP-binding cassette family member Rli1 (ABCE1 in humans) and the prolyl hydroxylase Tpa1. The influence of these modifications and their correlation with codon bias in the dynamic control of protein biosynthesis, mainly in response to stress, is emerging as an interesting focus of research. Taking S. cerevisiae as a model, we hereby discuss the relevance of iron in the control of global and specific translation steps.
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11
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eIF4E Overexpression Is Associated with Poor Prognoses of Ovarian Cancer. ACTA ACUST UNITED AC 2021; 2020:8984526. [PMID: 33489719 PMCID: PMC7787841 DOI: 10.1155/2020/8984526] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2020] [Revised: 09/20/2020] [Accepted: 11/30/2020] [Indexed: 11/17/2022]
Abstract
Aim Ovarian cancer is a common malignant tumor of the gynecological oncology worldwide, with a high incidence and mortality rate and poor prognosis. Searching for new diagnostic molecular biomarkers for ovarian cancer is extremely significant. Methods Here, we analyzed the expression rates of eIF4E and cyclin D1 proteins in 123 cases of cancer tissue samples and 38 cases of paracancerous tissue samples and studied the connection between the expression rates of eIF4E and cyclin D1 proteins by immunohistochemistry and statistically correlated with clinicopathological features in ovarian cancer. Results The results showed that the expression rates of eIF4E and cyclin D1 proteins in ovarian cancer tissues were significantly higher than those in noncancerous epithelial ovarian tissues (P = 0.001 and P = 0.032, respectively). Additionally, the results revealed that a higher expression rate of eIF4E (P = 0.008) was found in the advanced stage (stage III/IV), and also patients with cervical lymph node metastasis displayed higher expression of eIF4E (P < 0.001) and cyclin D1 (P = 0.033) than those without lymph node metastasis. Spearman's rank correlation test showed that there was a significant positive correlation between the eIF4E and cyclin D1 proteins in ovarian cancer. The Kaplan-Meier method showed that patients with lower expression of eIF4E had marginally better survival than those with high expression of eIF4E (P = 0.012). Multivariate Cox regression analysis further identified that positive expression of eIF4E was an independent prognostic factor. Conclusion In ovarian cancer, eIF4E might be a valuable biomarker to predict poor prognoses and a potential therapeutic target to develop valid treatment strategies.
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Hawer H, Mendelsohn BA, Mayer K, Kung A, Malhotra A, Tuupanen S, Schleit J, Brinkmann U, Schaffrath R. Diphthamide-deficiency syndrome: a novel human developmental disorder and ribosomopathy. Eur J Hum Genet 2020; 28:1497-1508. [PMID: 32576952 PMCID: PMC7575589 DOI: 10.1038/s41431-020-0668-y] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2020] [Revised: 04/06/2020] [Accepted: 05/28/2020] [Indexed: 02/06/2023] Open
Abstract
We describe a novel type of ribosomopathy that is defined by deficiency in diphthamidylation of translation elongation factor 2. The ribosomopathy was identified by correlating phenotypes and biochemical properties of previously described patients with diphthamide biosynthesis gene 1 (DPH1) deficiencies with a new patient that carried inactivating mutations in both alleles of the human diphthamide biosynthesis gene 2 (DPH2). The human DPH1 syndrome is an autosomal recessive disorder associated with developmental delay, abnormal head circumference (microcephaly or macrocephaly), short stature, and congenital heart disease. It is defined by variants with reduced functionality of the DPH1 gene observed so far predominantly in consanguineous homozygous patients carrying identical mutant alleles of DPH1. Here we report a child with a very similar phenotype carrying biallelic variants of the human DPH2. The gene products DPH1 and DPH2 are components of a heterodimeric enzyme complex that mediates the first step of the posttranslational diphthamide modification on the nonredundant eukaryotic translation elongation factor 2 (eEF2). Diphthamide deficiency was shown to reduce the accuracy of ribosomal protein biosynthesis. Both DPH2 variants described here severely impair diphthamide biosynthesis as demonstrated in human and yeast cells. This is the first report of a patient carrying compound heterozygous DPH2 loss-of-function variants with a DPH1 syndrome-like phenotype and implicates diphthamide deficiency as the root cause of this patient's clinical phenotype as well as of DPH1-syndrome. These findings define "diphthamide-deficiency syndrome" as a special ribosomopathy due to reduced functionality of components of the cellular machinery for eEF2-diphthamide synthesis.
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Affiliation(s)
- Harmen Hawer
- Fachgebiet Mikrobiologie, Institut für Biologie, Universität Kassel, D-34132, Kassel, Hessen, Germany
| | | | - Klaus Mayer
- Roche Pharma Research & Early Development, Large Molecule Research, Roche Innovation Center Munich, D-82377, Penzberg, Bavaria, Germany
| | - Ann Kung
- Kaiser Permanente Oakland Medical Center, Oakland, CA, 94611, USA
| | - Amit Malhotra
- Kaiser Permanente Oakland Medical Center, Oakland, CA, 94611, USA
| | - Sari Tuupanen
- Blueprint Genetics Oy, Keilaranta 16 A-B, 02150, Espoo, Finland
| | | | - Ulrich Brinkmann
- Roche Pharma Research & Early Development, Large Molecule Research, Roche Innovation Center Munich, D-82377, Penzberg, Bavaria, Germany.
| | - Raffael Schaffrath
- Fachgebiet Mikrobiologie, Institut für Biologie, Universität Kassel, D-34132, Kassel, Hessen, Germany
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Liu J, Zuo Z, Zou M, Finkel T, Liu S. Identification of the transcription factor Miz1 as an essential regulator of diphthamide biosynthesis using a CRISPR-mediated genome-wide screen. PLoS Genet 2020; 16:e1009068. [PMID: 33057331 PMCID: PMC7591051 DOI: 10.1371/journal.pgen.1009068] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2020] [Revised: 10/27/2020] [Accepted: 08/20/2020] [Indexed: 12/15/2022] Open
Abstract
Diphthamide is a unique post-translationally modified histidine residue (His715 in all mammals) found only in eukaryotic elongation factor-2 (eEF-2). The biosynthesis of diphthamide represents one of the most complex modifications, executed by protein factors conserved from yeast to humans. Diphthamide is not only essential for normal physiology (such as ensuring fidelity of mRNA translation), but is also exploited by bacterial ADP-ribosylating toxins (e.g., diphtheria toxin) as their molecular target in pathogenesis. Taking advantage of the observation that cells defective in diphthamide biosynthesis are resistant to ADP-ribosylating toxins, in the past four decades, seven essential genes (Dph1 to Dph7) have been identified for diphthamide biosynthesis. These technically unsaturated screens raise the question as to whether additional genes are required for diphthamide biosynthesis. In this study, we performed two independent, saturating, genome-wide CRISPR knockout screens in human cells. These screens identified all previously known Dph genes, as well as further identifying the BTB/POZ domain-containing transcription factor Miz1. We found that Miz1 is absolutely required for diphthamide biosynthesis via its role in the transcriptional regulation of Dph1 expression. Mechanistically, Miz1 binds to the Dph1 proximal promoter via an evolutionarily conserved consensus binding site to activate Dph1 transcription. Therefore, this work demonstrates that Dph1-7, along with the newly identified Miz1 transcription factor, are likely to represent the essential protein factors required for diphthamide modification on eEF2. Diphthamide is a unique post-translationally modified histidine residue (His699 in yeast, His715 in all mammals) found only in eukaryotic elongation factor-2 (eEF-2). Mice that are deficient in diphthamide biosynthesis are embryonic lethal, attesting to the importance of diphthamide in normal physiology. It has taken four decades to identify the seven non-redundant genes in diphthamide biosynthesis, but whether additional factors are required and how the pathway is regulated remained elusive. To address these issues, we performed two saturating, independent, and unbiased genome-wide CRISPR knockout screens. The screens concluded independently that Dph1-Dph7 and additionally transcription factor Miz1 are the key factors required for diphthamide biosynthesis. Mechanistically, Miz1 binds to the Dph1 proximal promoter via an evolutionarily conserved consensus binding site to activate Dph1 transcription. While diphthamide biosynthesis machinery (Dph1-Dph7) exists across eukaryotes, Miz1 orthologues do not exist in lower species such as yeast, C. elegans, and Drosophila, indicating that the regulation of diphthamide modification by Miz1 emerged much later in evolution. The work opens a new avenue for understanding the role that diphthamide modification plays in normal physiology and bacterial toxin pathogenesis.
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Affiliation(s)
- Jie Liu
- Aging Institute of University of Pittsburgh and University of Pittsburgh Medical Center, Pittsburgh, PA, United States of America
- Division of Cardiology, Department of Medicine, University of Pittsburgh School of Medicine, Pittsburgh, PA, United States of America
| | - Zehua Zuo
- Aging Institute of University of Pittsburgh and University of Pittsburgh Medical Center, Pittsburgh, PA, United States of America
| | - Meijuan Zou
- Aging Institute of University of Pittsburgh and University of Pittsburgh Medical Center, Pittsburgh, PA, United States of America
| | - Toren Finkel
- Aging Institute of University of Pittsburgh and University of Pittsburgh Medical Center, Pittsburgh, PA, United States of America
- Division of Cardiology, Department of Medicine, University of Pittsburgh School of Medicine, Pittsburgh, PA, United States of America
| | - Shihui Liu
- Aging Institute of University of Pittsburgh and University of Pittsburgh Medical Center, Pittsburgh, PA, United States of America
- Division of Infectious Diseases, Department of Medicine, University of Pittsburgh School of Medicine, Pittsburgh, PA, United States of America
- * E-mail:
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Cavadas B, Camacho R, Ferreira JC, Ferreira RM, Figueiredo C, Brazma A, Fonseca NA, Pereira L. Gastric Microbiome Diversities in Gastric Cancer Patients from Europe and Asia Mimic the Human Population Structure and Are Partly Driven by Microbiome Quantitative Trait Loci. Microorganisms 2020; 8:microorganisms8081196. [PMID: 32781641 PMCID: PMC7463948 DOI: 10.3390/microorganisms8081196] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2020] [Revised: 07/31/2020] [Accepted: 08/02/2020] [Indexed: 12/15/2022] Open
Abstract
The human gastrointestinal tract harbors approximately 100 trillion microorganisms with different microbial compositions across geographic locations. In this work, we used RNASeq data from stomach samples of non-disease (164 individuals from European ancestry) and gastric cancer patients (137 from Europe and Asia) from public databases. Although these data were intended to characterize the human expression profiles, they allowed for a reliable inference of the microbiome composition, as confirmed from measures such as the genus coverage, richness and evenness. The microbiome diversity (weighted UniFrac distances) in gastric cancer mimics host diversity across the world, with European gastric microbiome profiles clustering together, distinct from Asian ones. Despite the confirmed loss of microbiome diversity from a healthy status to a cancer status, the structured profile was still recognized in the disease condition. In concordance with the parallel host-bacteria population structure, we found 16 human loci (non-synonymous variants) in the European-descendent cohorts that were significantly associated with specific genera abundance. These microbiome quantitative trait loci display heterogeneity between population groups, being mainly linked to the immune system or cellular features that may play a role in enabling microbe colonization and inflammation.
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Affiliation(s)
- Bruno Cavadas
- i3S-Instituto de Investigação e Inovação em Saúde, Universidade do Porto, 4200-135 Porto, Portugal; (J.C.F.); (R.M.F.); (C.F.); (L.P.)
- IPATIMUP—Instituto de Patologia e Imunologia Molecular, Universidade do Porto, 4200-135 Porto, Portugal
- ICBAS—Instituto de Ciências Biomédicas Abel Salazar, Universidade do Porto, 4050-313 Porto, Portugal
- Correspondence:
| | - Rui Camacho
- FEUP-Faculdade de Engenharia, Universidade do Porto, 4200-465 Porto, Portugal;
- INESC TEC—Instituto de Engenharia de Sistemas e Computadores, Tecnologia e Ciência, Universidade do Porto, 4200-465 Porto, Portugal
| | - Joana C. Ferreira
- i3S-Instituto de Investigação e Inovação em Saúde, Universidade do Porto, 4200-135 Porto, Portugal; (J.C.F.); (R.M.F.); (C.F.); (L.P.)
- IPATIMUP—Instituto de Patologia e Imunologia Molecular, Universidade do Porto, 4200-135 Porto, Portugal
- ICBAS—Instituto de Ciências Biomédicas Abel Salazar, Universidade do Porto, 4050-313 Porto, Portugal
| | - Rui M. Ferreira
- i3S-Instituto de Investigação e Inovação em Saúde, Universidade do Porto, 4200-135 Porto, Portugal; (J.C.F.); (R.M.F.); (C.F.); (L.P.)
- IPATIMUP—Instituto de Patologia e Imunologia Molecular, Universidade do Porto, 4200-135 Porto, Portugal
| | - Ceu Figueiredo
- i3S-Instituto de Investigação e Inovação em Saúde, Universidade do Porto, 4200-135 Porto, Portugal; (J.C.F.); (R.M.F.); (C.F.); (L.P.)
- IPATIMUP—Instituto de Patologia e Imunologia Molecular, Universidade do Porto, 4200-135 Porto, Portugal
- Faculdade de Medicina, Universidade do Porto, 4200-319 Porto, Portugal
| | - Alvis Brazma
- European Molecular Biology Laboratory, European Bioinformatics Institute, EMBL-EBI, Wellcome Trust Genome Campus, Hinxton, Cambridge CB10 1SD, UK;
| | - Nuno A. Fonseca
- CIBIO—Centro de Investigação em Biodiversidade e Recursos Genético, Universidade do Porto, 4485-661 Vairão, Portugal;
| | - Luísa Pereira
- i3S-Instituto de Investigação e Inovação em Saúde, Universidade do Porto, 4200-135 Porto, Portugal; (J.C.F.); (R.M.F.); (C.F.); (L.P.)
- IPATIMUP—Instituto de Patologia e Imunologia Molecular, Universidade do Porto, 4200-135 Porto, Portugal
- Faculdade de Medicina, Universidade do Porto, 4200-319 Porto, Portugal
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Abstract
Mitochondria are essential in most eukaryotes and are involved in numerous biological functions including ATP production, cofactor biosyntheses, apoptosis, lipid synthesis, and steroid metabolism. Work over the past two decades has uncovered the biogenesis of cellular iron-sulfur (Fe/S) proteins as the essential and minimal function of mitochondria. This process is catalyzed by the bacteria-derived iron-sulfur cluster assembly (ISC) machinery and has been dissected into three major steps: de novo synthesis of a [2Fe-2S] cluster on a scaffold protein; Hsp70 chaperone-mediated trafficking of the cluster and insertion into [2Fe-2S] target apoproteins; and catalytic conversion of the [2Fe-2S] into a [4Fe-4S] cluster and subsequent insertion into recipient apoproteins. ISC components of the first two steps are also required for biogenesis of numerous essential cytosolic and nuclear Fe/S proteins, explaining the essentiality of mitochondria. This review summarizes the molecular mechanisms underlying the ISC protein-mediated maturation of mitochondrial Fe/S proteins and the importance for human disease.
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Affiliation(s)
- Roland Lill
- Institut für Zytobiologie, Philipps-Universität Marburg, 35032 Marburg, Germany;
- SYNMIKRO Zentrum für synthetische Mikrobiologie, Philipps-Universität Marburg, 35043 Marburg, Germany
| | - Sven-A Freibert
- Institut für Zytobiologie, Philipps-Universität Marburg, 35032 Marburg, Germany;
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Tsuda-Sakurai K, Kimura M, Miura M. Diphthamide modification of eEF2 is required for gut tumor-like hyperplasia induced by oncogenic Ras. Genes Cells 2019; 25:76-85. [PMID: 31828897 DOI: 10.1111/gtc.12742] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2019] [Revised: 10/27/2019] [Accepted: 11/20/2019] [Indexed: 01/16/2023]
Abstract
Eukaryotic elongation factor 2 (eEF2) undergoes a unique post-translational modification called diphthamidation. Although eEF2 diphthamidation is highly conserved, its pathophysiological function is still largely unknown. To elucidate the function of diphthamidation in tumor, we examined the involvement of diphthamidation pathway enzyme Dph5 in tumor progression in Drosophila adult gut. Expression of oncogenic RasV12 in gut intestinal stem cells (ISCs) and enteroblasts (EBs) causes hypertrophy and disruption of gut epithelia, and shortened life span. Knockdown of Dph5 ameliorated these pathogenic phenotypes. Dph5 is required for gross translation activation and high dMyc protein level in RasV12 tumor-like hyperplasia. Transcriptome analysis revealed that Dph5 is involved in the regulation of ribosome biogenesis genes. These results suggest that diphthamidation is required for translation activation partly through the regulation of ribosome biogenesis in Ras-induced tumor-like hyperplasia model in Drosophila gut.
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Affiliation(s)
- Kayoko Tsuda-Sakurai
- Department of Genetics, Graduate School of Pharmaceutical Sciences, The University of Tokyo, Tokyo, Japan
| | - Masaki Kimura
- Department of Genetics, Graduate School of Pharmaceutical Sciences, The University of Tokyo, Tokyo, Japan
| | - Masayuki Miura
- Department of Genetics, Graduate School of Pharmaceutical Sciences, The University of Tokyo, Tokyo, Japan
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Dong M, Dando EE, Kotliar I, Su X, Dzikovski B, Freed JH, Lin H. The asymmetric function of Dph1-Dph2 heterodimer in diphthamide biosynthesis. J Biol Inorg Chem 2019; 24:777-782. [PMID: 31463593 DOI: 10.1007/s00775-019-01702-0] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2019] [Accepted: 08/06/2019] [Indexed: 01/12/2023]
Abstract
Diphthamide, the target of diphtheria toxin, is a post-translationally modified histidine residue found in archaeal and eukaryotic translation elongation factor 2 (EF2). In the first step of diphthamide biosynthesis, a [4Fe-4S] cluster-containing radical SAM enzyme, Dph1-Dph2 heterodimer in eukaryotes or Dph2 homodimer in archaea, cleaves S-adenosylmethionine and transfers the 3-amino-3-carboxypropyl group to EF2. It was demonstrated previously that for the archaeal Dph2 homodimer, only one [4Fe-4S] cluster is necessary for the in vitro activity. Here, we demonstrate that for the eukaryotic Dph1-Dph2 heterodimer, the [4Fe-4S] cluster-binding cysteine residues in each subunit are required for diphthamide biosynthesis to occur in vivo. Furthermore, our in vitro reconstitution experiments with Dph1-Dph2 mutants suggested that the Dph1 cluster serves a catalytic role, while the Dph2 cluster facilitates the reduction of the Dph1 cluster by the physiological reducing system Dph3/Cbr1/NADH. Our results reveal the asymmetric functional roles of the Dph1-Dph2 heterodimer and may help to understand how the Fe-S clusters in radical SAM enzymes are reduced in biology.
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Affiliation(s)
- Min Dong
- Department of Chemistry and Chemical Biology, Cornell University, Ithaca, NY, 14853, USA
- Key Laboratory of Systems Bioengineering (Ministry of Education), School of Chemical Engineering and Technology, Tianjin University, Tianjin, 300072, China
| | - Emily E Dando
- Department of Chemistry and Chemical Biology, Cornell University, Ithaca, NY, 14853, USA
| | - Ilana Kotliar
- Department of Chemistry and Chemical Biology, Cornell University, Ithaca, NY, 14853, USA
| | - Xiaoyang Su
- Department of Chemistry and Chemical Biology, Cornell University, Ithaca, NY, 14853, USA
| | - Boris Dzikovski
- Department of Chemistry and Chemical Biology, Cornell University, Ithaca, NY, 14853, USA
| | - Jack H Freed
- Department of Chemistry and Chemical Biology, Cornell University, Ithaca, NY, 14853, USA
| | - Hening Lin
- Department of Chemistry and Chemical Biology, Cornell University, Ithaca, NY, 14853, USA.
- Howard Hughes Medical Institute, Cornell University, Ithaca, NY, 14853, USA.
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Roles of Elongator Dependent tRNA Modification Pathways in Neurodegeneration and Cancer. Genes (Basel) 2018; 10:genes10010019. [PMID: 30597914 PMCID: PMC6356722 DOI: 10.3390/genes10010019] [Citation(s) in RCA: 34] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2018] [Revised: 12/18/2018] [Accepted: 12/20/2018] [Indexed: 02/07/2023] Open
Abstract
Transfer RNA (tRNA) is subject to a multitude of posttranscriptional modifications which can profoundly impact its functionality as the essential adaptor molecule in messenger RNA (mRNA) translation. Therefore, dynamic regulation of tRNA modification in response to environmental changes can tune the efficiency of gene expression in concert with the emerging epitranscriptomic mRNA regulators. Several of the tRNA modifications are required to prevent human diseases and are particularly important for proper development and generation of neurons. In addition to the positive role of different tRNA modifications in prevention of neurodegeneration, certain cancer types upregulate tRNA modification genes to sustain cancer cell gene expression and metastasis. Multiple associations of defects in genes encoding subunits of the tRNA modifier complex Elongator with human disease highlight the importance of proper anticodon wobble uridine modifications (xm⁵U34) for health. Elongator functionality requires communication with accessory proteins and dynamic phosphorylation, providing regulatory control of its function. Here, we summarized recent insights into molecular functions of the complex and the role of Elongator dependent tRNA modification in human disease.
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