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Hayek H, Eriani G, Allmang C. eIF3 Interacts with Selenoprotein mRNAs. Biomolecules 2022; 12:biom12091268. [PMID: 36139107 PMCID: PMC9496622 DOI: 10.3390/biom12091268] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2022] [Revised: 09/01/2022] [Accepted: 09/05/2022] [Indexed: 11/16/2022] Open
Abstract
The synthesis of selenoproteins requires the co-translational recoding of an in-frame UGASec codon. Interactions between the Selenocysteine Insertion Sequence (SECIS) and the SECIS binding protein 2 (SBP2) in the 3'untranslated region (3'UTR) of selenoprotein mRNAs enable the recruitment of the selenocysteine insertion machinery. Several selenoprotein mRNAs undergo unusual cap hypermethylation and are not recognized by the translation initiation factor 4E (eIF4E) but nevertheless translated. The human eukaryotic translation initiation factor 3 (eIF3), composed of 13 subunits (a-m), can selectively recruit several cellular mRNAs and plays roles in specialized translation initiation. Here, we analyzed the ability of eIF3 to interact with selenoprotein mRNAs. By combining ribonucleoprotein immunoprecipitation (RNP IP) in vivo and in vitro with cross-linking experiments, we found interactions between eIF3 and a subgroup of selenoprotein mRNAs. We showed that eIF3 preferentially interacts with hypermethylated capped selenoprotein mRNAs rather than m7G-capped mRNAs. We identified direct contacts between GPx1 mRNA and eIF3 c, d, and e subunits and showed the existence of common interaction patterns for all hypermethylated capped selenoprotein mRNAs. Differential interactions of eIF3 with selenoprotein mRNAs may trigger specific translation pathways independent of eIF4E. eIF3 could represent a new player in the translation regulation and hierarchy of selenoprotein expression.
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Affiliation(s)
- Hassan Hayek
- Architecture et Réactivité de l’ARN, Université de Strasbourg, Centre National de la Recherche Scientifique, Institut de Biologie Moléculaire et Cellulaire, 67084 Strasbourg, France
- Department of Microbiology, Immunology, and Inflammation, Center for Inflammation and Lung Research, Temple University, Philadelphia, PA 19140, USA
| | - Gilbert Eriani
- Architecture et Réactivité de l’ARN, Université de Strasbourg, Centre National de la Recherche Scientifique, Institut de Biologie Moléculaire et Cellulaire, 67084 Strasbourg, France
| | - Christine Allmang
- Architecture et Réactivité de l’ARN, Université de Strasbourg, Centre National de la Recherche Scientifique, Institut de Biologie Moléculaire et Cellulaire, 67084 Strasbourg, France
- Correspondence:
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2
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Copeland PR, Howard MT. Ribosome Fate during Decoding of UGA-Sec Codons. Int J Mol Sci 2021; 22:ijms222413204. [PMID: 34948001 PMCID: PMC8704476 DOI: 10.3390/ijms222413204] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2021] [Revised: 11/29/2021] [Accepted: 12/06/2021] [Indexed: 12/14/2022] Open
Abstract
Decoding of genetic information into polypeptides occurs during translation, generally following the codon assignment rules of the organism's genetic code. However, recoding signals in certain mRNAs can overwrite the normal rules of translation. An exquisite example of this occurs during translation of selenoprotein mRNAs, wherein UGA codons are reassigned to encode for the 21st proteogenic amino acid, selenocysteine. In this review, we will examine what is known about the mechanisms of UGA recoding and discuss the fate of ribosomes that fail to incorporate selenocysteine.
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Affiliation(s)
- Paul R. Copeland
- Department of Biochemistry and Molecular Biology, Rutgers-Robert Wood Johnson Medical School, Piscataway, NJ 08854, USA
- Correspondence: (P.R.C.); (M.T.H.)
| | - Michael T. Howard
- Department of Human Genetics, University of Utah, Salt Lake City, UT 84112, USA
- Correspondence: (P.R.C.); (M.T.H.)
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3
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Santesmasses D, Gladyshev VN. Pathogenic Variants in Selenoproteins and Selenocysteine Biosynthesis Machinery. Int J Mol Sci 2021; 22:11593. [PMID: 34769022 PMCID: PMC8584023 DOI: 10.3390/ijms222111593] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2021] [Revised: 10/22/2021] [Accepted: 10/22/2021] [Indexed: 01/07/2023] Open
Abstract
Selenium is incorporated into selenoproteins as the 21st amino acid selenocysteine (Sec). There are 25 selenoproteins encoded in the human genome, and their synthesis requires a dedicated machinery. Most selenoproteins are oxidoreductases with important functions in human health. A number of disorders have been associated with deficiency of selenoproteins, caused by mutations in selenoprotein genes or Sec machinery genes. We discuss mutations that are known to cause disease in humans and report their allele frequencies in the general population. The occurrence of protein-truncating variants in the same genes is also presented. We provide an overview of pathogenic variants in selenoproteins genes from a population genomics perspective.
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Affiliation(s)
| | - Vadim N. Gladyshev
- Division of Genetics, Department of Medicine, Brigham and Women’s Hospital, Harvard Medical School, Boston, MA 02115, USA;
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4
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MicroSalmon: A Comprehensive, Searchable Resource of Predicted MicroRNA Targets and 3'UTR Cis-Regulatory Elements in the Full-Length Sequenced Atlantic Salmon Transcriptome. Noncoding RNA 2021; 7:ncrna7040061. [PMID: 34698276 PMCID: PMC8544657 DOI: 10.3390/ncrna7040061] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2021] [Revised: 09/17/2021] [Accepted: 09/20/2021] [Indexed: 12/20/2022] Open
Abstract
Complete 3′UTRs unambiguously assigned to specific mRNA isoforms from the Atlantic salmon full-length (FL) transcriptome were collected into a 3′UTRome. miRNA response elements (MREs) and other cis-regulatory motifs were subsequently predicted and assigned to 3′UTRs of all FL-transcripts. The MicroSalmon GitHub repository provides all results. RNAHybrid and sRNAtoolbox tools predicted the MREs. UTRscan and the Teiresias algorithm predicted other 3′UTR cis-acting motifs, both known vertebrate motifs and putative novel motifs. MicroSalmon provides search programs to retrieve all FL-transcripts targeted by a miRNA (median number 1487), all miRNAs targeting an FL-transcript (median number 27), and other cis-acting motifs. As thousands of FL-transcripts may be targets of each miRNA, additional experimental strategies are necessary to reduce the likely true and relevant targets to a number that may be functionally validated. Low-complexity motifs known to affect mRNA decay in vertebrates were over-represented. Many of these were enriched in the terminal end, while purine- or pyrimidine-rich motifs with unknown functions were enriched immediately downstream of the stop codon. Furthermore, several novel complex motifs were over-represented, indicating conservation and putative function. In conclusion, MicroSalmon is an extensive and useful, searchable resource for study of Atlantic salmon transcript regulation by miRNAs and cis-acting 3′UTR motifs.
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5
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Schoenmakers E, Chatterjee K. Human Disorders Affecting the Selenocysteine Incorporation Pathway Cause Systemic Selenoprotein Deficiency. Antioxid Redox Signal 2020; 33:481-497. [PMID: 32295391 PMCID: PMC7409586 DOI: 10.1089/ars.2020.8097] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Significance: Generalized selenoprotein deficiency has been associated with mutations in SECISBP2, SEPSECS, and TRU-TCA1-1, 3 factors that are crucial for incorporation of the amino acid selenocysteine (Sec) into at least 25 human selenoproteins. SECISBP2 and TRU-TCA1-1 defects are characterized by a multisystem phenotype due to deficiencies of antioxidant and tissue-specific selenoproteins, together with abnormal thyroid hormone levels reflecting impaired hormone metabolism by deiodinase selenoenzymes. SEPSECS mutations are associated with a predominantly neurological phenotype with progressive cerebello-cerebral atrophy. Recent Advances: The recent identification of individuals with defects in genes encoding components of the selenocysteine insertion pathway has delineated complex and multisystem disorders, reflecting a lack of selenoproteins in specific tissues, oxidative damage due to lack of oxidoreductase-active selenoproteins and other pathways whose nature is unclear. Critical Issues: Abnormal thyroid hormone metabolism in patients can be corrected by triiodothyronine (T3) treatment. No specific therapies for other phenotypes (muscular dystrophy, male infertility, hearing loss, neurodegeneration) exist as yet, but their severity often requires supportive medical intervention. Future Directions: These disorders provide unique insights into the role of selenoproteins in humans. The long-term consequences of reduced cellular antioxidant capacity remain unknown, and future surveillance of patients may reveal time-dependent phenotypes (e.g., neoplasia, aging) or consequences of deficiency of selenoproteins whose function remains to be elucidated. The role of antioxidant therapies requires evaluation. Antioxid. Redox Signal. 33, 481-497.
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Affiliation(s)
- Erik Schoenmakers
- Metabolic Research Laboratories, Wellcome Trust-MRC Institute of Metabolic Science, Addenbrooke's Hospital, University of Cambridge, United Kingdom
| | - Krishna Chatterjee
- Metabolic Research Laboratories, Wellcome Trust-MRC Institute of Metabolic Science, Addenbrooke's Hospital, University of Cambridge, United Kingdom
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6
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Zhao W, Bohleber S, Schmidt H, Seeher S, Howard MT, Braun D, Arndt S, Reuter U, Wende H, Birchmeier C, Fradejas-Villar N, Schweizer U. Ribosome profiling of selenoproteins in vivo reveals consequences of pathogenic Secisbp2 missense mutations. J Biol Chem 2019; 294:14185-14200. [PMID: 31350336 DOI: 10.1074/jbc.ra119.009369] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2019] [Revised: 07/08/2019] [Indexed: 01/31/2023] Open
Abstract
Recoding of UGA codons as selenocysteine (Sec) codons in selenoproteins depends on a selenocysteine insertion sequence (SECIS) in the 3'-UTR of mRNAs of eukaryotic selenoproteins. SECIS-binding protein 2 (SECISBP2) increases the efficiency of this process. Pathogenic mutations in SECISBP2 reduce selenoprotein expression and lead to phenotypes associated with the reduction of deiodinase activities and selenoprotein N expression in humans. Two functions have been ascribed to SECISBP2: binding of SECIS elements in selenoprotein mRNAs and facilitation of co-translational Sec insertion. To separately probe both functions, we established here two mouse models carrying two pathogenic missense mutations in Secisbp2 previously identified in patients. We found that the C696R substitution in the RNA-binding domain abrogates SECIS binding and does not support selenoprotein translation above the level of a complete Secisbp2 null mutation. The R543Q missense substitution located in the selenocysteine insertion domain resulted in residual activity and caused reduced selenoprotein translation, as demonstrated by ribosomal profiling to determine the impact on UGA recoding in individual selenoproteins. We found, however, that the R543Q variant is thermally unstable in vitro and completely degraded in the mouse liver in vivo, while being partially functional in the brain. The moderate impairment of selenoprotein expression in neurons led to astrogliosis and transcriptional induction of genes associated with immune responses. We conclude that differential SECISBP2 protein stability in individual cell types may dictate clinical phenotypes to a much greater extent than molecular interactions involving a mutated amino acid in SECISBP2.
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Affiliation(s)
- Wenchao Zhao
- Institut für Biochemie und Molekularbiologie, Rheinische Friedrich-Wilhelms-Universität Bonn, 53115 Bonn, Germany
| | - Simon Bohleber
- Institut für Biochemie und Molekularbiologie, Rheinische Friedrich-Wilhelms-Universität Bonn, 53115 Bonn, Germany
| | - Henrik Schmidt
- Institut für Biochemie und Molekularbiologie, Rheinische Friedrich-Wilhelms-Universität Bonn, 53115 Bonn, Germany
| | - Sandra Seeher
- Institut für Biochemie und Molekularbiologie, Rheinische Friedrich-Wilhelms-Universität Bonn, 53115 Bonn, Germany
| | - Michael T Howard
- Department of Genetics, University of Utah, Salt Lake City, Utah 84112
| | - Doreen Braun
- Institut für Biochemie und Molekularbiologie, Rheinische Friedrich-Wilhelms-Universität Bonn, 53115 Bonn, Germany
| | - Simone Arndt
- Institut für Biochemie und Molekularbiologie, Rheinische Friedrich-Wilhelms-Universität Bonn, 53115 Bonn, Germany
| | - Uschi Reuter
- Institut für Biochemie und Molekularbiologie, Rheinische Friedrich-Wilhelms-Universität Bonn, 53115 Bonn, Germany
| | - Hagen Wende
- Max Delbrück Center of Molecular Medicine, 13125 Berlin, Germany
| | | | - Noelia Fradejas-Villar
- Institut für Biochemie und Molekularbiologie, Rheinische Friedrich-Wilhelms-Universität Bonn, 53115 Bonn, Germany
| | - Ulrich Schweizer
- Institut für Biochemie und Molekularbiologie, Rheinische Friedrich-Wilhelms-Universität Bonn, 53115 Bonn, Germany
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7
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Lynham J, Houry WA. The Multiple Functions of the PAQosome: An R2TP- and URI1 Prefoldin-Based Chaperone Complex. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2018; 1106:37-72. [DOI: 10.1007/978-3-030-00737-9_4] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
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8
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Dai Y, Liang S, Huang Y, Chen L, Banerjee S. Targeted next generation sequencing identifies two novel mutations in SEPN1 in rigid spine muscular dystrophy 1. Oncotarget 2018; 7:83843-83849. [PMID: 27863379 PMCID: PMC5356628 DOI: 10.18632/oncotarget.13337] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2016] [Accepted: 11/08/2016] [Indexed: 11/25/2022] Open
Abstract
Rigid spine muscular dystrophy 1 (RSMD1) is a neuromuscular disorder, manifested with poor axial muscle strength, scoliosis and neck weakness, and a variable degree of spinal rigidity with an early ventilatory insufficiency which can lead to death by respiratory failure. Mutations of SEPN1 gene are associated with autosomal recessive RSMD1. Here, we present a clinical molecular study of a Chinese proband with RSMD1. The proband is a 17 years old male, showing difficulty in feeding, delayed motor response, problem in running with frequent fall down, early onset respiratory insufficiency, general muscle weakness and rigid cervical spine. Muscle biopsy identified increased variability of fiber size with atrophic muscle cells consistent with non-specific myopathic changes. Proband's elder brother presented with same phenotype as the proband and died at the age of 15 years due to acute respiratory failure. Proband's father and mother are phenotypically normal. Targeted exome capture based next generation sequencing and Sanger sequencing identified that the proband was a compound heterozygote with two novel mutations in SEPN1 gene; a novel missense mutation (c.1384T>C; p.Sec462Arg) and a novel nonsense mutation (c.1525C>T; p.Gln509Ter), inherited from his father and mother respectively. These two mutations are co-segregated with the disease phenotypes in the proband and was absent in normal healthy controls. Our present study expands the mutational spectrum of the SEPN1 associated RSMD1.
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Affiliation(s)
- Yi Dai
- Department of Neurology, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences, Beijing, Beijing, China
| | | | - Yan Huang
- Department of Neurology, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences, Beijing, Beijing, China
| | - Lin Chen
- Department of Neurology, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences, Beijing, Beijing, China
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9
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Labunskyy VM, Hatfield DL, Gladyshev VN. Selenoproteins: molecular pathways and physiological roles. Physiol Rev 2014; 94:739-77. [PMID: 24987004 DOI: 10.1152/physrev.00039.2013] [Citation(s) in RCA: 829] [Impact Index Per Article: 82.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023] Open
Abstract
Selenium is an essential micronutrient with important functions in human health and relevance to several pathophysiological conditions. The biological effects of selenium are largely mediated by selenium-containing proteins (selenoproteins) that are present in all three domains of life. Although selenoproteins represent diverse molecular pathways and biological functions, all these proteins contain at least one selenocysteine (Sec), a selenium-containing amino acid, and most serve oxidoreductase functions. Sec is cotranslationally inserted into nascent polypeptide chains in response to the UGA codon, whose normal function is to terminate translation. To decode UGA as Sec, organisms evolved the Sec insertion machinery that allows incorporation of this amino acid at specific UGA codons in a process requiring a cis-acting Sec insertion sequence (SECIS) element. Although the basic mechanisms of Sec synthesis and insertion into proteins in both prokaryotes and eukaryotes have been studied in great detail, the identity and functions of many selenoproteins remain largely unknown. In the last decade, there has been significant progress in characterizing selenoproteins and selenoproteomes and understanding their physiological functions. We discuss current knowledge about how these unique proteins perform their functions at the molecular level and highlight new insights into the roles that selenoproteins play in human health.
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Affiliation(s)
- Vyacheslav M Labunskyy
- Division of Genetics, Department of Medicine, Brigham and Women's Hospital and Harvard Medical School, Boston, Massachusetts; and Molecular Biology of Selenium Section, Mouse Cancer Genetics Program, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, Maryland
| | - Dolph L Hatfield
- Division of Genetics, Department of Medicine, Brigham and Women's Hospital and Harvard Medical School, Boston, Massachusetts; and Molecular Biology of Selenium Section, Mouse Cancer Genetics Program, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, Maryland
| | - Vadim N Gladyshev
- Division of Genetics, Department of Medicine, Brigham and Women's Hospital and Harvard Medical School, Boston, Massachusetts; and Molecular Biology of Selenium Section, Mouse Cancer Genetics Program, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, Maryland
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10
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Rothé B, Saliou JM, Quinternet M, Back R, Tiotiu D, Jacquemin C, Loegler C, Schlotter F, Peña V, Eckert K, Moréra S, Dorsselaer AV, Branlant C, Massenet S, Sanglier-Cianférani S, Manival X, Charpentier B. Protein Hit1, a novel box C/D snoRNP assembly factor, controls cellular concentration of the scaffolding protein Rsa1 by direct interaction. Nucleic Acids Res 2014; 42:10731-47. [PMID: 25170085 PMCID: PMC4176330 DOI: 10.1093/nar/gku612] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2014] [Revised: 06/23/2014] [Accepted: 06/24/2014] [Indexed: 01/09/2023] Open
Abstract
Biogenesis of eukaryotic box C/D small nucleolar ribonucleoprotein particles (C/D snoRNPs) involves conserved trans-acting factors, which are proposed to facilitate the assembly of the core proteins Snu13p/15.5K, Nop58p/NOP58, Nop56p/NOP56 and Nop1p/Fibrillarin on box C/D small nucleolar RNAs (C/D snoRNAs). In yeast, protein Rsa1 acts as a platform, interacting with both the RNA-binding core protein Snu13 and protein Pih1 of the Hsp82-R2TP chaperone complex. In this work, a proteomic approach coupled with functional and structural studies identifies protein Hit1 as a novel Rsa1p-interacting partner involved in C/D snoRNP assembly. Hit1p contributes to in vivo C/D snoRNA stability and pre-RNA maturation kinetics. It associates with U3 snoRNA precursors and influences its 3'-end processing. Remarkably, Hit1p is required to maintain steady-state levels of Rsa1p. This stabilizing activity is likely to be general across eukaryotic species, as the human protein ZNHIT3(TRIP3) showing sequence homology with Hit1p regulates the abundance of NUFIP1, the Rsa1p functional homolog. The nuclear magnetic resonance solution structure of the Rsa1p317-352-Hit1p70-164 complex reveals a novel mode of protein-protein association explaining the strong stability of the Rsa1p-Hit1p complex. Our biochemical data show that C/D snoRNAs and the core protein Nop58 can interact with the purified Snu13p-Rsa1p-Hit1p heterotrimer.
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Affiliation(s)
- Benjamin Rothé
- Ingénierie Moléculaire et Physiopathologie Articulaire (IMoPA), UMR 7365 CNRS Université de Lorraine, Biopôle, Campus Biologie Santé, 9 avenue de la forêt de Haye, CS 50184, 54505 Vandœuvre-lès-Nancy, France
| | - Jean-Michel Saliou
- Laboratoire de Spectrométrie de Masse BioOrganique (LSMBO), IPHC-DSA, Université de Strasbourg. CNRS, UMR 7178, 25 rue Becquerel, 67087 Strasbourg, France
| | - Marc Quinternet
- FR CNRS-3209 Bioingénierie Moléculaire, Cellulaire et Thérapeutique (BMCT), CNRS, Université de Lorraine, Biopôle, Campus Biologie Santé, CS 50184, 54505 Vandœuvre-lès-Nancy Cedex, France
| | - Régis Back
- Ingénierie Moléculaire et Physiopathologie Articulaire (IMoPA), UMR 7365 CNRS Université de Lorraine, Biopôle, Campus Biologie Santé, 9 avenue de la forêt de Haye, CS 50184, 54505 Vandœuvre-lès-Nancy, France
| | - Decebal Tiotiu
- Ingénierie Moléculaire et Physiopathologie Articulaire (IMoPA), UMR 7365 CNRS Université de Lorraine, Biopôle, Campus Biologie Santé, 9 avenue de la forêt de Haye, CS 50184, 54505 Vandœuvre-lès-Nancy, France
| | - Clémence Jacquemin
- Ingénierie Moléculaire et Physiopathologie Articulaire (IMoPA), UMR 7365 CNRS Université de Lorraine, Biopôle, Campus Biologie Santé, 9 avenue de la forêt de Haye, CS 50184, 54505 Vandœuvre-lès-Nancy, France
| | - Christine Loegler
- Ingénierie Moléculaire et Physiopathologie Articulaire (IMoPA), UMR 7365 CNRS Université de Lorraine, Biopôle, Campus Biologie Santé, 9 avenue de la forêt de Haye, CS 50184, 54505 Vandœuvre-lès-Nancy, France
| | - Florence Schlotter
- Ingénierie Moléculaire et Physiopathologie Articulaire (IMoPA), UMR 7365 CNRS Université de Lorraine, Biopôle, Campus Biologie Santé, 9 avenue de la forêt de Haye, CS 50184, 54505 Vandœuvre-lès-Nancy, France
| | - Vlad Peña
- Max-Planck-Institut für biophysikalische Chemie, Abtl. Röntgenkristallographie, Am Fassberg 11, 37077 Göttingen, Germany
| | - Kelvin Eckert
- Laboratoire d'Enzymologie et Biochimie Structurales (LEBS), CNRS, 1 Avenue de Terrasse, 91198 Gif-sur Yvette, France
| | - Solange Moréra
- Laboratoire d'Enzymologie et Biochimie Structurales (LEBS), CNRS, 1 Avenue de Terrasse, 91198 Gif-sur Yvette, France
| | - Alain Van Dorsselaer
- Laboratoire de Spectrométrie de Masse BioOrganique (LSMBO), IPHC-DSA, Université de Strasbourg. CNRS, UMR 7178, 25 rue Becquerel, 67087 Strasbourg, France
| | - Christiane Branlant
- Ingénierie Moléculaire et Physiopathologie Articulaire (IMoPA), UMR 7365 CNRS Université de Lorraine, Biopôle, Campus Biologie Santé, 9 avenue de la forêt de Haye, CS 50184, 54505 Vandœuvre-lès-Nancy, France
| | - Séverine Massenet
- Ingénierie Moléculaire et Physiopathologie Articulaire (IMoPA), UMR 7365 CNRS Université de Lorraine, Biopôle, Campus Biologie Santé, 9 avenue de la forêt de Haye, CS 50184, 54505 Vandœuvre-lès-Nancy, France
| | - Sarah Sanglier-Cianférani
- Laboratoire de Spectrométrie de Masse BioOrganique (LSMBO), IPHC-DSA, Université de Strasbourg. CNRS, UMR 7178, 25 rue Becquerel, 67087 Strasbourg, France
| | - Xavier Manival
- Ingénierie Moléculaire et Physiopathologie Articulaire (IMoPA), UMR 7365 CNRS Université de Lorraine, Biopôle, Campus Biologie Santé, 9 avenue de la forêt de Haye, CS 50184, 54505 Vandœuvre-lès-Nancy, France
| | - Bruno Charpentier
- Ingénierie Moléculaire et Physiopathologie Articulaire (IMoPA), UMR 7365 CNRS Université de Lorraine, Biopôle, Campus Biologie Santé, 9 avenue de la forêt de Haye, CS 50184, 54505 Vandœuvre-lès-Nancy, France
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11
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Wurth L, Gribling-Burrer AS, Verheggen C, Leichter M, Takeuchi A, Baudrey S, Martin F, Krol A, Bertrand E, Allmang C. Hypermethylated-capped selenoprotein mRNAs in mammals. Nucleic Acids Res 2014; 42:8663-77. [PMID: 25013170 PMCID: PMC4117793 DOI: 10.1093/nar/gku580] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Mammalian mRNAs are generated by complex and coordinated biogenesis pathways and acquire 5′-end m7G caps that play fundamental roles in processing and translation. Here we show that several selenoprotein mRNAs are not recognized efficiently by translation initiation factor eIF4E because they bear a hypermethylated cap. This cap modification is acquired via a 5′-end maturation pathway similar to that of the small nucle(ol)ar RNAs (sn- and snoRNAs). Our findings also establish that the trimethylguanosine synthase 1 (Tgs1) interacts with selenoprotein mRNAs for cap hypermethylation and that assembly chaperones and core proteins devoted to sn- and snoRNP maturation contribute to recruiting Tgs1 to selenoprotein mRNPs. We further demonstrate that the hypermethylated-capped selenoprotein mRNAs localize to the cytoplasm, are associated with polysomes and thus translated. Moreover, we found that the activity of Tgs1, but not of eIF4E, is required for the synthesis of the GPx1 selenoprotein in vivo.
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Affiliation(s)
- Laurence Wurth
- Architecture et Réactivité de l'ARN, Université de Strasbourg, Centre National de la Recherche Scientifique, Institut de Biologie Moléculaire et Cellulaire, 67084 Strasbourg, France
| | - Anne-Sophie Gribling-Burrer
- Architecture et Réactivité de l'ARN, Université de Strasbourg, Centre National de la Recherche Scientifique, Institut de Biologie Moléculaire et Cellulaire, 67084 Strasbourg, France
| | - Céline Verheggen
- Equipe labélisée Ligue contre le cancer, Institut de Génétique Moléculaire, Centre National de la Recherche Scientifique, UMR 5535, 34293 Montpellier, France
| | - Michael Leichter
- Architecture et Réactivité de l'ARN, Université de Strasbourg, Centre National de la Recherche Scientifique, Institut de Biologie Moléculaire et Cellulaire, 67084 Strasbourg, France
| | - Akiko Takeuchi
- Architecture et Réactivité de l'ARN, Université de Strasbourg, Centre National de la Recherche Scientifique, Institut de Biologie Moléculaire et Cellulaire, 67084 Strasbourg, France
| | - Stéphanie Baudrey
- Architecture et Réactivité de l'ARN, Université de Strasbourg, Centre National de la Recherche Scientifique, Institut de Biologie Moléculaire et Cellulaire, 67084 Strasbourg, France
| | - Franck Martin
- Architecture et Réactivité de l'ARN, Université de Strasbourg, Centre National de la Recherche Scientifique, Institut de Biologie Moléculaire et Cellulaire, 67084 Strasbourg, France
| | - Alain Krol
- Architecture et Réactivité de l'ARN, Université de Strasbourg, Centre National de la Recherche Scientifique, Institut de Biologie Moléculaire et Cellulaire, 67084 Strasbourg, France
| | - Edouard Bertrand
- Equipe labélisée Ligue contre le cancer, Institut de Génétique Moléculaire, Centre National de la Recherche Scientifique, UMR 5535, 34293 Montpellier, France
| | - Christine Allmang
- Architecture et Réactivité de l'ARN, Université de Strasbourg, Centre National de la Recherche Scientifique, Institut de Biologie Moléculaire et Cellulaire, 67084 Strasbourg, France
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Otero L, Romanelli-Cedrez L, Turanov AA, Gladyshev VN, Miranda-Vizuete A, Salinas G. Adjustments, extinction, and remains of selenocysteine incorporation machinery in the nematode lineage. RNA (NEW YORK, N.Y.) 2014; 20:1023-1034. [PMID: 24817701 PMCID: PMC4114682 DOI: 10.1261/rna.043877.113] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/09/2013] [Accepted: 03/06/2014] [Indexed: 06/03/2023]
Abstract
Selenocysteine (Sec) is encoded by an UGA codon with the help of a SECIS element present in selenoprotein mRNAs. SECIS-binding protein (SBP2/SCBP-2) mediates Sec insertion, but the roles of its domains and the impact of its deficiency on Sec insertion are not fully understood. We used Caenorhabditis elegans to examine SBP2 function since it possesses a single selenoprotein, thioredoxin reductase-1 (TRXR-1). All SBP2 described so far have an RNA-binding domain (RBD) and a Sec-incorporation domain (SID). Surprisingly, C. elegans SBP2 lacks SID and consists only of an RBD. An sbp2 deletion mutant strain ablated Sec incorporation demonstrating SBP2 essentiality for Sec incorporation. Further in silico analyses of nematode genomes revealed conservation of SBP2 lacking SID and maintenance of Sec incorporation linked to TRXR-1. Remarkably, parasitic plant nematodes lost the ability to incorporate Sec, but retained SecP43, a gene associated with Sec incorporation. Interestingly, both selenophosphate synthetase (SPS) genes are absent in plant parasitic nematodes, while only Cys-containing SPS2 is present in Sec-incorporating nematodes. Our results indicate that C. elegans and the nematode lineage provide key insights into Sec incorporation and the evolution of Sec utilization trait, selenoproteomes, selenoproteins, and Sec residues. Finally, our study provides evidence of noncanonical translation initiation in C. elegans, not previously known for this well-established animal model.
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Affiliation(s)
- Lucía Otero
- Cátedra de Inmunología, Facultad de Química, Instituto de Higiene, Universidad de la República, Montevideo 11600, Uruguay
| | - Laura Romanelli-Cedrez
- Cátedra de Inmunología, Facultad de Química, Instituto de Higiene, Universidad de la República, Montevideo 11600, Uruguay
| | - Anton A. Turanov
- Division of Genetics, Department of Medicine, Brigham and Women's Hospital and Harvard Medical School, Boston, Massachusetts 02115, USA
| | - Vadim N. Gladyshev
- Division of Genetics, Department of Medicine, Brigham and Women's Hospital and Harvard Medical School, Boston, Massachusetts 02115, USA
| | - Antonio Miranda-Vizuete
- Instituto de Biomedicina de Sevilla (IBIS), Hospital Universitario Virgen del Rocío/CSIC/Universidad de Sevilla, 41013 Sevilla, Spain
- Departamento de Fisiología, Anatomía y Biología Celular, Centro Andaluz de Biología del Desarrollo (CABD-CSIC), Universidad Pablo de Olavide, 41013 Sevilla, Spain
| | - Gustavo Salinas
- Cátedra de Inmunología, Facultad de Química, Instituto de Higiene, Universidad de la República, Montevideo 11600, Uruguay
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Kossinova O, Malygin A, Krol A, Karpova G. The SBP2 protein central to selenoprotein synthesis contacts the human ribosome at expansion segment 7L of the 28S rRNA. RNA (NEW YORK, N.Y.) 2014; 20:1046-1056. [PMID: 24850884 PMCID: PMC4114684 DOI: 10.1261/rna.044917.114] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/20/2014] [Accepted: 03/27/2014] [Indexed: 05/31/2023]
Abstract
SBP2 is a pivotal protein component in selenoprotein synthesis. It binds the SECIS stem-loop in the 3' UTR of selenoprotein mRNA and interacts with both the specialized translation elongation factor and the ribosome at the 60S subunit. In this work, our goal was to identify the binding partners of SBP2 on the ribosome. Cross-linking experiments with bifunctional reagents demonstrated that the SBP2-binding site on the human ribosome is mainly formed by the 28S rRNA. Direct hydroxyl radical probing of the entire 28S rRNA revealed that SBP2 bound to 80S ribosomes or 60S subunits protects helix ES7L-E in expansion segment 7 of the 28S rRNA. Diepoxybutane cross-linking confirmed the interaction of SBP2 with helix ES7L-E. Additionally, binding of SBP2 to the ribosome led to increased reactivity toward chemical probes of a few bases in ES7L-E and in the universally conserved helix H89, indicative of conformational changes in the 28S rRNA in response to SBP2 binding. This study revealed for the first time that SBP2 makes direct contacts with a discrete region of the human 28S rRNA.
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Affiliation(s)
- Olga Kossinova
- Institute of Chemical Biology and Fundamental Medicine, Siberian Branch of the Russian Academy of Sciences, Novosibirsk 630090, Russia
- Architecture et Réactivité de l'ARN, Université de Strasbourg, CNRS, IBMC, 67084 Strasbourg, France
| | - Alexey Malygin
- Institute of Chemical Biology and Fundamental Medicine, Siberian Branch of the Russian Academy of Sciences, Novosibirsk 630090, Russia
| | - Alain Krol
- Architecture et Réactivité de l'ARN, Université de Strasbourg, CNRS, IBMC, 67084 Strasbourg, France
| | - Galina Karpova
- Institute of Chemical Biology and Fundamental Medicine, Siberian Branch of the Russian Academy of Sciences, Novosibirsk 630090, Russia
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Rothé B, Back R, Quinternet M, Bizarro J, Robert MC, Blaud M, Romier C, Manival X, Charpentier B, Bertrand E, Branlant C. Characterization of the interaction between protein Snu13p/15.5K and the Rsa1p/NUFIP factor and demonstration of its functional importance for snoRNP assembly. Nucleic Acids Res 2013; 42:2015-36. [PMID: 24234454 PMCID: PMC3919607 DOI: 10.1093/nar/gkt1091] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023] Open
Abstract
The yeast Snu13p protein and its 15.5K human homolog both bind U4 snRNA and box C/D snoRNAs. They also bind the Rsa1p/NUFIP assembly factor, proposed to scaffold immature snoRNPs and to recruit the Hsp90-R2TP chaperone complex. However, the nature of the Snu13p/15.5K–Rsa1p/NUFIP interaction and its exact role in snoRNP assembly remained to be elucidated. By using biophysical, molecular and imaging approaches, here, we identify residues needed for Snu13p/15.5K–Rsa1p/NUFIP interaction. By NMR structure determination and docking approaches, we built a 3D model of the Snup13p–Rsa1p interface, suggesting that residues R249, R246 and K250 in Rsa1p and E72 and D73 in Snu13p form a network of electrostatic interactions shielded from the solvent by hydrophobic residues from both proteins and that residue W253 of Rsa1p is inserted in a hydrophobic cavity of Snu13p. Individual mutations of residues in yeast demonstrate the functional importance of the predicted interactions for both cell growth and snoRNP formation. Using archaeal box C/D sRNP 3D structures as templates, the association of Snu13p with Rsa1p is predicted to be exclusive of interactions in active snoRNPs. Rsa1p and NUFIP may thus prevent premature activity of pre-snoRNPs, and their removal may be a key step for active snoRNP production.
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Affiliation(s)
- Benjamin Rothé
- Ingénierie Moléculaire et Physiopathologie Articulaire (IMoPA), UMR 7365 CNRS Université de Lorraine, Biopôle de l'Université de Lorraine, Campus Biologie Santé, 9 avenue de la forêt de Haye, BP 184, 54505 Vandœuvre-lès-Nancy, France, FR CNRS-3209 (Ingénierie Moléculaire et Thérapeutique), CNRS, Université de Lorraine, Faculté de Médecine, Bâtiment Biopôle, BP 184, 54505 Vandœuvre-lès-Nancy Cedex, France, Equipe labellisée Ligue contre le Cancer, IGMM (Institut de Génétique Moléculaire de Montpellier), Centre National de la Recherche Scientifique, Unité Mixte de Recherche 5535, Montpellier Cedex 5, France and IGBMC (Institut de Génétique et Biologie Moléculaire et Cellulaire), Département de Biologie et Génomique Structurales, Université de Strasbourg, CNRS, INSERM, 1 Rue Laurent Fries, BP 10142, 67404 Illkirch Cedex, France
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15
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Kossinova O, Malygin A, Krol A, Karpova G. A novel insight into the mechanism of mammalian selenoprotein synthesis. RNA (NEW YORK, N.Y.) 2013; 19:1147-58. [PMID: 23788723 PMCID: PMC3708534 DOI: 10.1261/rna.036871.112] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/10/2023]
Abstract
The amino acid selenocysteine is encoded by UGA, usually a stop codon, thus requiring a specialized machinery to enable its incorporation into selenoproteins. The machinery comprises the tRNA(Sec), a 3'-UTR mRNA stem-loop termed SElenoCysteine Insertion Sequence (SECIS), which is mandatory for recoding UGA as a Sec codon, the SECIS Binding Protein 2 (SBP2), and other proteins. Little is known about the molecular mechanism and, in particular, when, where, and how the SECIS and SBP2 contact the ribosome. Previous work by others used the isolated SECIS RNA to address this question. Here, we developed a novel approach using instead engineered minimal selenoprotein mRNAs containing SECIS elements derivatized with photoreactive groups. By cross-linking experiments in rabbit reticulocyte lysate, new information could be gained about the SBP2 and SECIS contacts with components of the translation machinery at various translation steps. In particular, we found that SBP2 was bound only to the SECIS in 48S pre-initiation and 80S pretranslocation complexes. In the complex where the Sec-tRNA(Sec) was accommodated to the A site but transpeptidation was blocked, SBP2 bound the ribosome and possibly the SECIS element as well, and the SECIS had flexible contacts with the 60S ribosomal subunit involving several ribosomal proteins. Altogether, our findings led to broadening our understanding about the unique mechanism of selenocysteine incorporation in mammals.
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Affiliation(s)
- Olga Kossinova
- Institute of Chemical Biology and Fundamental Medicine, Siberian Branch of the Russian Academy of Sciences, Novosibirsk, 630090, Russia
- Architecture et Réactivité de l’ARN, Université de Strasbourg, CNRS, IBMC, 67084 Strasbourg, France
| | - Alexey Malygin
- Institute of Chemical Biology and Fundamental Medicine, Siberian Branch of the Russian Academy of Sciences, Novosibirsk, 630090, Russia
| | - Alain Krol
- Architecture et Réactivité de l’ARN, Université de Strasbourg, CNRS, IBMC, 67084 Strasbourg, France
- Corresponding authorsE-mail E-mail
| | - Galina Karpova
- Institute of Chemical Biology and Fundamental Medicine, Siberian Branch of the Russian Academy of Sciences, Novosibirsk, 630090, Russia
- Corresponding authorsE-mail E-mail
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16
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Bifano AL, Atassi T, Ferrara T, Driscoll DM. Identification of nucleotides and amino acids that mediate the interaction between ribosomal protein L30 and the SECIS element. BMC Mol Biol 2013; 14:12. [PMID: 23777426 PMCID: PMC3706390 DOI: 10.1186/1471-2199-14-12] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2013] [Accepted: 06/11/2013] [Indexed: 12/29/2022] Open
Abstract
Background Ribosomal protein L30 belongs to the L7Ae family of RNA-binding proteins, which recognize diverse targets. L30 binds to kink-turn motifs in the 28S ribosomal RNA, L30 pre-mRNA, and mature L30 mRNA. L30 has a noncanonical function as a component of the UGA recoding machinery that incorporates selenocysteine (Sec) into selenoproteins during translation. L30 binds to a putative kink-turn motif in the Sec Insertion Sequence (SECIS) element in the 3’ UTR of mammalian selenoprotein mRNAs. The SECIS also interacts with SECIS-binding protein 2 (SBP2), an essential factor for Sec incorporation. Previous studies showed that L30 and SBP2 compete for binding to the SECIS in vitro. The SBP2:SECIS interaction has been characterized but much less is known about how L30 recognizes the SECIS. Results Here we use enzymatic RNA footprinting to define the L30 binding site on the SECIS. Like SBP2, L30 protects nucleotides in the 5’ side of the internal loop, the 5’ side of the lower helix, and the SECIS core, including the GA tandem base pairs that are predicted to form a kink-turn. However, L30 has additional determinants for binding as it also protects nucleotides in the 3’ side of the internal loop, which are not protected by SBP2. In support of the competitive binding model, we found that purified L30 repressed UGA recoding in an in vitro translation system, and that this inhibition was rescued by SBP2. To define the amino acid requirements for SECIS-binding, site-specific mutations in L30 were generated based on published structural studies of this protein in a complex with its canonical target, the L30 pre-mRNA. We identified point mutations that selectively inhibited binding of L30 to the SECIS, to the L30 pre-mRNA, or both RNAs, suggesting that there are subtle differences in how L30 interacts with the two targets. Conclusions This study establishes that L30 and SBP2 bind to overlapping but non-identical sites on the SECIS. The amino acid requirements for the interaction of L30 with the SECIS differ from those that mediate binding to the L30 pre-mRNA. Our results provide insight into how L7Ae family members recognize their cognate RNAs.
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Affiliation(s)
- Abby L Bifano
- Department of Cellular & Molecular Medicine, Lerner Research Institute, Cleveland Clinic, Cleveland, OH 44195, USA
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Bubenik JL, Miniard AC, Driscoll DM. Alternative transcripts and 3'UTR elements govern the incorporation of selenocysteine into selenoprotein S. PLoS One 2013; 8:e62102. [PMID: 23614019 PMCID: PMC3628699 DOI: 10.1371/journal.pone.0062102] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2013] [Accepted: 03/16/2013] [Indexed: 01/01/2023] Open
Abstract
Selenoprotein S (SelS) is a 189 amino acid trans-membrane protein that plays an important yet undefined role in the unfolded protein response. It has been proposed that SelS may function as a reductase, with the penultimate selenocysteine (Sec188) residue participating in a selenosulfide bond with cysteine (Cys174). Cotranslational incorporation of Sec into SelS depends on the recoding of the UGA codon, which requires a Selenocysteine Insertion Sequence (SECIS) element in the 3′UTR of the transcript. Here we identify multiple mechanisms that regulate the expression of SelS. The human SelS gene encodes two transcripts (variants 1 and 2), which differ in their 3′UTR sequences due to an alternative splicing event that removes the SECIS element from the variant 1 transcript. Both transcripts are widely expressed in human cell lines, with the SECIS-containing variant 2 mRNA being more abundant. In vitro experiments demonstrate that the variant 1 3′UTR does not allow readthrough of the UGA/Sec codon. Thus, this transcript would produce a truncated protein that does not contain Sec and cannot make the selenosulfide bond. While the variant 2 3′UTR does support Sec insertion, its activity is weak. Bioinformatic analysis revealed two highly conserved stem-loop structures, one in the proximal part of the variant 2 3′UTR and the other immediately downstream of the SECIS element. The proximal stem-loop promotes Sec insertion in the native context but not when positioned far from the UGA/Sec codon in a heterologous mRNA. In contrast, the 140 nucleotides downstream of the SECIS element inhibit Sec insertion. We also show that endogenous SelS is enriched at perinuclear speckles, in addition to its known localization in the endoplasmic reticulum. Our results suggest the expression of endogenous SelS is more complex than previously appreciated, which has implications for past and future studies on the function of this protein.
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Affiliation(s)
- Jodi L. Bubenik
- Department of Cellular and Molecular Medicine, Lerner Research Institute, Cleveland Clinic, Cleveland, Ohio, United States of America
- * E-mail: (JLB); (DMD)
| | - Angela C. Miniard
- Department of Cellular and Molecular Medicine, Lerner Research Institute, Cleveland Clinic, Cleveland, Ohio, United States of America
| | - Donna M. Driscoll
- Department of Cellular and Molecular Medicine, Lerner Research Institute, Cleveland Clinic, Cleveland, Ohio, United States of America
- Department of Molecular Medicine, Cleveland Clinic Lerner College of Medicine of Case Western Reserve University, Cleveland, Ohio, United States of America
- * E-mail: (JLB); (DMD)
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18
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Latrèche L, Duhieu S, Touat-Hamici Z, Jean-Jean O, Chavatte L. The differential expression of glutathione peroxidase 1 and 4 depends on the nature of the SECIS element. RNA Biol 2012; 9:681-90. [PMID: 22614831 DOI: 10.4161/rna.20147] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Abstract
Selenocysteine insertion into selenoproteins involves the translational recoding of UGA stop codons. In mammals, selenoprotein expression further depends on selenium availability, which has been particularly described for glutathione peroxidase 1 and 4 (Gpx1 and Gpx4). The SECIS element located in the 3'UTR of the selenoprotein mRNAs is a modulator of UGA recoding efficiency in adequate selenium conditions. One of the current models for the UGA recoding mechanism proposes that the SECIS binds SECIS-binding protein 2 (SBP2), which then recruits a selenocysteine-specific elongation factor (EFsec) and tRNA (Sec) to the ribosome, where L30 acts as an anchor. The involvement of the SECIS in modulation of UGA recoding activity was investigated, together with SBP2 and EFsec, in Hek293 cells cultured with various selenium levels. Luciferase reporter constructs, in transiently or stably expressing cell lines, were used to analyze the differential expression of Gpx1 and Gpx4. We showed that, upon selenium fluctuation, the modulation of UGA recoding efficiency depends on the nature of the SECIS, with Gpx1 being more sensitive than Gpx4. Attenuation of SBP2 and EFsec levels by shRNAs confirmed that both factors are essential for efficient selenocysteine insertion. Strikingly, in a context of either EFsec or SBP2 attenuation, the decrease in UGA recoding efficiency is dependent on the nature of the SECIS, GPx1 being more sensitive. Finally, the profusion of selenium of the culture medium exacerbates the lack of factors involved in selenocysteine insertion.
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19
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Selenocysteine insertion sequence binding protein 2L is implicated as a novel post-transcriptional regulator of selenoprotein expression. PLoS One 2012; 7:e35581. [PMID: 22530054 PMCID: PMC3328465 DOI: 10.1371/journal.pone.0035581] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2012] [Accepted: 03/19/2012] [Indexed: 01/20/2023] Open
Abstract
The amino acid selenocysteine (Sec) is encoded by UGA codons. Recoding of UGA from stop to Sec requires a Sec insertion sequence (SECIS) element in the 3′ UTR of selenoprotein mRNAs. SECIS binding protein 2 (SBP2) binds the SECIS element and is essential for Sec incorporation into the nascent peptide. SBP2-like (SBP2L) is a paralogue of SBP2 in vertebrates and is the only SECIS binding protein in some invertebrates where it likely directs Sec incorporation. However, vertebrate SBP2L does not promote Sec incorporation in in vitro assays. Here we present a comparative analysis of SBP2 and SBP2L SECIS binding properties and demonstrate that its inability to promote Sec incorporation is not due to lower SECIS affinity but likely due to lack of a SECIS dependent domain association that is found in SBP2. Interestingly, however, we find that an invertebrate version of SBP2L is fully competent for Sec incorporation in vitro. Additionally, we present the first evidence that SBP2L interacts with selenoprotein mRNAs in mammalian cells, thereby implying a role in selenoprotein expression.
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20
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Boulon S, Bertrand E, Pradet-Balade B. HSP90 and the R2TP co-chaperone complex: building multi-protein machineries essential for cell growth and gene expression. RNA Biol 2012; 9:148-54. [PMID: 22418846 DOI: 10.4161/rna.18494] [Citation(s) in RCA: 50] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023] Open
Abstract
HSP90 (Heat Shock Protein 90) is an essential chaperone involved in the last folding steps of client proteins. It has many clients, and these are often recognized through specific adaptors. Recently, the conserved R2TP complex was identified as a key HSP90 co-chaperone. Current evidences indicate that the HSP90/R2TP system assembles multi-molecular protein complexes. Strikingly, these comprise basic machineries of gene expression: (1) nuclear RNA polymerases; (2) the snoRNPs, essential to produce ribosomes; and (3) mTOR Complex 1 and 2, which control translational activity and cell growth. Another important substrate is the telomerase RNP, required for continuous cell proliferation. We discuss here the assembly of RNA polymerases in bacteria and eukaryotes, the role of HSP90/R2TP in this process and in the assembly of snoRNPs and the PIKK family of TORC1 kinase. Finally, we speculate on the roles of R2TP as a master regulator of cell growth under normal or pathological conditions.
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Affiliation(s)
- Séverine Boulon
- Centre de Recherche de Biochimie Macromoléculaire, CNRS, Université Montpellier; Montpellier, France
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21
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Kawaguchi A, Ose T, Yao M, Tanaka I. Crystallization and preliminary X-ray structure analysis of human ribosomal protein L30e. Acta Crystallogr Sect F Struct Biol Cryst Commun 2011; 67:1516-1518. [PMID: 22139155 PMCID: PMC3232128 DOI: 10.1107/s1744309111045131] [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: 10/03/2011] [Accepted: 10/27/2011] [Indexed: 05/31/2023]
Abstract
Many functions have been reported for the eukaryotic ribosomal protein L30e. L30e makes several inter-subunit and intra-subunit interactions with protein or RNA components of the 80S ribosome. Yeast L30e has been shown to bind to its own transcript to autoregulate expression at both the transcriptional and the translational levels. Furthermore, it has been reported that mammalian L30e is a component of the selenocysteine-incorporation machinery by binding to the selenocysteine-insertion sequence on mRNA. As high-resolution crystal structures of mammalian L30e are not available, the purification, crystallization and X-ray structure analysis of human L30e are presented here.
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Affiliation(s)
- Akiko Kawaguchi
- Graduate School of Life Sciences, Hokkaido University, Hokkaido, Sapporo 060-0810, Japan
| | - Toyoyuki Ose
- Faculty of Pharmaceutical Sciences, Hokkaido University, Hokkaido, Sapporo 060-0812, Japan
- Faculty of Advanced Life Sciences, Hokkaido University, Hokkaido, Sapporo 060-0810, Japan
| | - Min Yao
- Graduate School of Life Sciences, Hokkaido University, Hokkaido, Sapporo 060-0810, Japan
- Faculty of Advanced Life Sciences, Hokkaido University, Hokkaido, Sapporo 060-0810, Japan
| | - Isao Tanaka
- Graduate School of Life Sciences, Hokkaido University, Hokkaido, Sapporo 060-0810, Japan
- Faculty of Advanced Life Sciences, Hokkaido University, Hokkaido, Sapporo 060-0810, Japan
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22
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Sytnikova YA, Kubarenko AV, Schäfer A, Weber ANR, Niehrs C. Gadd45a is an RNA binding protein and is localized in nuclear speckles. PLoS One 2011; 6:e14500. [PMID: 21249130 PMCID: PMC3017548 DOI: 10.1371/journal.pone.0014500] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2010] [Accepted: 12/09/2010] [Indexed: 01/06/2023] Open
Abstract
Background The Gadd45 proteins play important roles in growth control, maintenance of genomic stability, DNA repair, and apoptosis. Recently, Gadd45 proteins have also been implicated in epigenetic gene regulation by promoting active DNA demethylation. Gadd45 proteins have sequence homology with the L7Ae/L30e/S12e RNA binding superfamily of ribosomal proteins, which raises the question if they may interact directly with nucleic acids. Principal Findings Here we show that Gadd45a binds RNA but not single- or double stranded DNA or methylated DNA in vitro. Sucrose density gradient centrifugation experiments demonstrate that Gadd45a is present in high molecular weight particles, which are RNase sensitive. Gadd45a displays RNase-sensitive colocalization in nuclear speckles with the RNA helicase p68 and the RNA binding protein SC35. A K45A point mutation defective in RNA binding was still active in DNA demethylation. This suggests that RNA binding is not absolutely essential for demethylation of an artificial substrate. A point mutation at G39 impared RNA binding, nuclear speckle localization and DNA demethylation, emphasizing its relevance for Gadd45a function. Significance The results implicate RNA in Gadd45a function and suggest that Gadd45a is associated with a ribonucleoprotein particle.
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Affiliation(s)
- Yuliya A. Sytnikova
- Division of Molecular Embryology, DKFZ-ZMBH Alliance, Krebsforschungszentrum, Heidelberg, Germany
| | - Andriy V. Kubarenko
- Division of Toll-like Receptors and Cancer, Deutsches Krebsforschungszentrum, Heidelberg, Germany
| | - Andrea Schäfer
- Division of Molecular Embryology, DKFZ-ZMBH Alliance, Krebsforschungszentrum, Heidelberg, Germany
| | - Alexander N. R. Weber
- Division of Toll-like Receptors and Cancer, Deutsches Krebsforschungszentrum, Heidelberg, Germany
| | - Christof Niehrs
- Division of Molecular Embryology, DKFZ-ZMBH Alliance, Krebsforschungszentrum, Heidelberg, Germany
- Institute of Molecular Biology (IMB), Mainz, Germany
- * E-mail:
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Ghalei H, Hsiao HH, Urlaub H, Wahl MC, Watkins NJ. A novel Nop5-sRNA interaction that is required for efficient archaeal box C/D sRNP formation. RNA (NEW YORK, N.Y.) 2010; 16:2341-8. [PMID: 20962039 PMCID: PMC2995396 DOI: 10.1261/rna.2380410] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/21/2010] [Accepted: 09/16/2010] [Indexed: 05/30/2023]
Abstract
Archaeal and eukaryotic box C/D RNPs catalyze the 2'-O-methylation of ribosomal RNA, a modification that is essential for the correct folding and function of the ribosome. Each archaeal RNP contains three core proteins--L7Ae, Nop5, and fibrillarin (methyltransferase)--and a box C/D sRNA. Base-pairing between the sRNA guide region and the rRNA directs target site selection with the C/D and related C'/D' motifs functioning as protein binding sites. Recent structural analysis of in vitro assembled archaeal complexes has produced two divergent models of box C/D sRNP structure. In one model, the complex is proposed to be monomeric, while the other suggests a dimeric sRNP. The position of the RNA in the RNP is significantly different in each model. We have used UV-cross-linking to characterize protein-RNA contacts in the in vitro assembled Pyrococcus furiosus box C/D sRNP. The P. furiosus sRNP components assemble into complexes that are the expected size of di-sRNPs. Analysis of UV-induced protein-RNA cross-links revealed a novel interaction between the ALFR motif, in the Nop domain of Nop5, and the guide/spacer regions of the sRNA. We show that the ALFR motif and the spacer sequence adjacent to box C or C' are important for box C/D sRNP assembly in vitro. These data therefore reveal new RNA-protein contacts in the box C/D sRNP and suggest a role for Nop5 in substrate binding and/or release.
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Affiliation(s)
- Homa Ghalei
- Abteilung Zelluläre Biochemie, Max-Planck-Institute for Biophysical Chemistry, D-37077 Goettingen, Germany
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24
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Abstract
Small nucleolar and Cajal body ribonucleoprotein particles (RNPs) are required for the maturation of ribosomes and spliceosomes. They consist of small nucleolar RNA or Cajal body RNA combined with partner proteins and represent the most complex RNA modification enzymes. Recent advances in structure and function studies have revealed detailed information regarding ribonucleoprotein assembly and substrate binding. These enzymes form intertwined RNA-protein assemblies that facilitate reversible binding of the large ribosomal RNA or small nuclear RNA. These revelations explain the specificity among the components in enzyme assembly and substrate modification. The multiple conformations of individual components and those of complete RNPs suggest a dynamic assembly process and justify the requirement of many assembly factors in vivo.
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Schroeder KT, McPhee SA, Ouellet J, Lilley DMJ. A structural database for k-turn motifs in RNA. RNA (NEW YORK, N.Y.) 2010; 16:1463-8. [PMID: 20562215 PMCID: PMC2905746 DOI: 10.1261/rna.2207910] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/05/2010] [Accepted: 05/10/2010] [Indexed: 05/19/2023]
Abstract
The kink-turn (k-turn) is a common structural motif in RNA that introduces a tight kink into the helical axis. k-turns play an important architectural role in RNA structures and serve as binding sites for a number of proteins. We have created a database of known and postulated k-turn sequences and three-dimensional (3D) structures, available via the internet. This site provides (1) a database of sequence and structure, as a resource for the RNA community, and (2) a tool to enable the manipulation and comparison of 3D structures where known.
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Affiliation(s)
- Kersten T Schroeder
- Cancer Research UK Nucleic Acid Structure Research Group, The University of Dundee, Dundee DD1 5EH, United Kingdom
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Abstract
The co-translational incorporation of selenocysteine (Sec) requires that UGA be recognized as a sense rather than a nonsense codon. This is accomplished by the concerted action of a Sec insertion sequence (SECIS) element, SECIS binding protein 2, and a ternary complex of the Sec specific elongation factor, Sec-tRNA(Sec), and GTP. The mechanism by which they alter the canonical protein synthesis reaction has been elusive. Here we present an overview of the mechanistic perspective on Sec incorporation, highlighting recent advances in the field.
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Affiliation(s)
- Jesse Donovan
- Department of Microbiology, Molecular Genetics, and Immunology, Graduate School of Biomedical Sciences, Robert Wood Johnson Medical School, University of Medicine and Dentistry of New Jersey, 675 Hoes Lane, Piscataway, NJ 08854, USA
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Gagnon KT, Zhang X, Qu G, Biswas S, Suryadi J, Brown BA, Maxwell ES. Signature amino acids enable the archaeal L7Ae box C/D RNP core protein to recognize and bind the K-loop RNA motif. RNA (NEW YORK, N.Y.) 2010; 16:79-90. [PMID: 19926724 PMCID: PMC2802039 DOI: 10.1261/rna.1692310] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/15/2009] [Accepted: 09/29/2009] [Indexed: 05/28/2023]
Abstract
The archaeal L7Ae and eukaryotic 15.5kD protein homologs are members of the L7Ae/15.5kD protein family that characteristically recognize K-turn motifs found in both archaeal and eukaryotic RNAs. In Archaea, the L7Ae protein uniquely binds the K-loop motif found in box C/D and H/ACA sRNAs, whereas the eukaryotic 15.5kD homolog is unable to recognize this variant K-turn RNA. Comparative sequence and structural analyses, coupled with amino acid replacement experiments, have demonstrated that five amino acids enable the archaeal L7Ae core protein to recognize and bind the K-loop motif. These signature residues are highly conserved in the archaeal L7Ae and eukaryotic 15.5kD homologs, but differ between the two domains of life. Interestingly, loss of K-loop binding by archaeal L7Ae does not disrupt C'/D' RNP formation or RNA-guided nucleotide modification. L7Ae is still incorporated into the C'/D' RNP despite its inability to bind the K-loop, thus indicating the importance of protein-protein interactions for RNP assembly and function. Finally, these five signature amino acids are distinct for each of the L7Ae/L30 family members, suggesting an evolutionary continuum of these RNA-binding proteins for recognition of the various K-turn motifs contained in their cognate RNAs.
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Affiliation(s)
- Keith T Gagnon
- Department of Molecular and Structural Biochemistry, North Carolina State University, Raleigh, North Carolina 27695, USA
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Donovan J, Copeland PR. Evolutionary history of selenocysteine incorporation from the perspective of SECIS binding proteins. BMC Evol Biol 2009; 9:229. [PMID: 19744324 PMCID: PMC2746813 DOI: 10.1186/1471-2148-9-229] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2009] [Accepted: 09/10/2009] [Indexed: 12/29/2022] Open
Abstract
Background The co-translational incorporation of selenocysteine into nascent polypeptides by recoding the UGA stop codon occurs in all domains of life. In eukaryotes, this event requires at least three specific factors: SECIS binding protein 2 (SBP2), a specific translation elongation factor (eEFSec), selenocysteinyl tRNA, and a cis-acting selenocysteine insertion sequence (SECIS) element in selenoprotein mRNAs. While the phylogenetic relationships of selenoprotein families and the evolution of selenocysteine usage are well documented, the evolutionary history of SECIS binding proteins has not been explored. Results In this report we present a phylogeny of the eukaryotic SECIS binding protein family which includes SBP2 and a related protein we herein term SBP2L. Here we show that SBP2L is an SBP2 paralogue in vertebrates and is the only form of SECIS binding protein in invertebrate deuterostomes, suggesting a key role in Sec incorporation in these organisms, but an SBP2/SBP2L fusion protein is unable to support Sec incorporation in vitro. An in-depth phylogenetic analysis of the conserved L7Ae RNA binding domain suggests an ancestral relationship with ribosomal protein L30. In addition, we describe the emergence of a motif upstream of the SBP2 RNA binding domain that shares significant similarity with a motif within the pseudouridine synthase Cbf5. Conclusion Our analysis suggests that SECIS binding proteins arose once in evolution but diverged significantly in multiple lineages. In addition, likely due to a gene duplication event in the early vertebrate lineage, SBP2 and SBP2L are paralogous in vertebrates.
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Affiliation(s)
- Jesse Donovan
- Department of Molecular Genetics, Microbiology, and Immunology, Graduate School of Biomedical Sciences, University of Medicine and Dentistry of New Jersey - Robert Wood Johnson Medical School, Piscataway, NJ, USA.
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Allmang C, Wurth L, Krol A. The selenium to selenoprotein pathway in eukaryotes: more molecular partners than anticipated. Biochim Biophys Acta Gen Subj 2009; 1790:1415-23. [PMID: 19285539 DOI: 10.1016/j.bbagen.2009.03.003] [Citation(s) in RCA: 122] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2009] [Revised: 03/03/2009] [Accepted: 03/05/2009] [Indexed: 01/23/2023]
Abstract
The amino acid selenocysteine (Sec) is the major biological form of the trace element selenium. Sec is co-translationally incorporated in selenoproteins. There are 25 selenoprotein genes in humans, and Sec was found in the active site of those that have been attributed a function. This review will discuss how selenocysteine is synthesized and incorporated into selenoproteins in eukaryotes. Sec biosynthesis from serine on the tRNA(Sec) requires four enzymes. Incorporation of Sec in response to an in-frame UGA codon, otherwise signaling termination of translation, is achieved by a complex recoding machinery to inform the ribosomes not to stop at this position on the mRNA. A number of the molecular partners acting in this machinery have been identified but their detailed mechanism of action has not been deciphered yet. Here we provide an overview of the literature in the field. Particularly striking is the higher than originally envisaged number of factors necessary to synthesize Sec and selenoproteins. Clearly, selenoprotein synthesis is an exciting and very active field of research.
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Affiliation(s)
- Christine Allmang
- Architecture et Réactivité de l'ARN - Université de Strasbourg, Centre National de la Recherche Scientifique, Institut de Biologie Moléculaire et Cellulaire, 67084 Strasbourg, France
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30
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Takeuchi A, Schmitt D, Chapple C, Babaylova E, Karpova G, Guigo R, Krol A, Allmang C. A short motif in Drosophila SECIS Binding Protein 2 provides differential binding affinity to SECIS RNA hairpins. Nucleic Acids Res 2009; 37:2126-41. [PMID: 19223320 PMCID: PMC2673426 DOI: 10.1093/nar/gkp078] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Selenoproteins contain the amino acid selenocysteine which is encoded by a UGA Sec codon. Recoding UGA Sec requires a complex mechanism, comprising the cis-acting SECIS RNA hairpin in the 3'UTR of selenoprotein mRNAs, and trans-acting factors. Among these, the SECIS Binding Protein 2 (SBP2) is central to the mechanism. SBP2 has been so far functionally characterized only in rats and humans. In this work, we report the characterization of the Drosophila melanogaster SBP2 (dSBP2). Despite its shorter length, it retained the same selenoprotein synthesis-promoting capabilities as the mammalian counterpart. However, a major difference resides in the SECIS recognition pattern: while human SBP2 (hSBP2) binds the distinct form 1 and 2 SECIS RNAs with similar affinities, dSBP2 exhibits high affinity toward form 2 only. In addition, we report the identification of a K (lysine)-rich domain in all SBP2s, essential for SECIS and 60S ribosomal subunit binding, differing from the well-characterized L7Ae RNA-binding domain. Swapping only five amino acids between dSBP2 and hSBP2 in the K-rich domain conferred reversed SECIS-binding properties to the proteins, thus unveiling an important sequence for form 1 binding.
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Affiliation(s)
- Akiko Takeuchi
- Architecture et Réactivité de l'ARN, Université de Strasbourg, CNRS, IBMC, Strasbourg, France
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31
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Donovan J, Caban K, Ranaweera R, Gonzalez-Flores JN, Copeland PR. A novel protein domain induces high affinity selenocysteine insertion sequence binding and elongation factor recruitment. J Biol Chem 2008; 283:35129-39. [PMID: 18948268 DOI: 10.1074/jbc.m806008200] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Selenocysteine (Sec) is incorporated at UGA codons in mRNAs possessing a Sec insertion sequence (SECIS) element in their 3'-untranslated region. At least three additional factors are necessary for Sec incorporation: SECIS-binding protein 2 (SBP2), Sec-tRNA(Sec), and a Sec-specific translation elongation factor (eEFSec). The C-terminal half of SBP2 is sufficient to promote Sec incorporation in vitro, which is carried out by the concerted action of a novel Sec incorporation domain and an L7Ae RNA-binding domain. Using alanine scanning mutagenesis, we show that two distinct regions of the Sec incorporation domain are required for Sec incorporation. Physical separation of the Sec incorporation and RNA-binding domains revealed that they are able to function in trans and established a novel role of the Sec incorporation domain in promoting SECIS and eEFSec binding to the SBP2 RNA-binding domain. We propose a model in which SECIS binding induces a conformational change in SBP2 that recruits eEFSec, which in concert with the Sec incorporation domain gains access to the ribosomal A site.
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Affiliation(s)
- Jesse Donovan
- Department of Molecular Genetics, Microbiology and Immunology, University of Medicine and Dentistry of New Jersey, Robert Wood Johnson Medical School, Piscataway, New Jersey 08854, USA
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32
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Boulon S, Marmier-Gourrier N, Pradet-Balade B, Wurth L, Verheggen C, Jády BE, Rothé B, Pescia C, Robert MC, Kiss T, Bardoni B, Krol A, Branlant C, Allmang C, Bertrand E, Charpentier B. The Hsp90 chaperone controls the biogenesis of L7Ae RNPs through conserved machinery. ACTA ACUST UNITED AC 2008; 180:579-95. [PMID: 18268104 PMCID: PMC2234240 DOI: 10.1083/jcb.200708110] [Citation(s) in RCA: 177] [Impact Index Per Article: 11.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
RNA-binding proteins of the L7Ae family are at the heart of many essential ribonucleoproteins (RNPs), including box C/D and H/ACA small nucleolar RNPs, U4 small nuclear RNP, telomerase, and messenger RNPs coding for selenoproteins. In this study, we show that Nufip and its yeast homologue Rsa1 are key components of the machinery that assembles these RNPs. We observed that Rsa1 and Nufip bind several L7Ae proteins and tether them to other core proteins in the immature particles. Surprisingly, Rsa1 and Nufip also link assembling RNPs with the AAA + adenosine triphosphatases hRvb1 and hRvb2 and with the Hsp90 chaperone through two conserved adaptors, Tah1/hSpagh and Pih1. Inhibition of Hsp90 in human cells prevents the accumulation of U3, U4, and telomerase RNAs and decreases the levels of newly synthesized hNop58, hNHP2, 15.5K, and SBP2. Thus, Hsp90 may control the folding of these proteins during the formation of new RNPs. This suggests that Hsp90 functions as a master regulator of cell proliferation by allowing simultaneous control of cell signaling and cell growth.
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Affiliation(s)
- Séverine Boulon
- Institute of Molecular Genetics of Montpellier, Centre National de la Recherche Scientifique, Unité Mixte de Recherche 5535, Montpellier Cedex 5, France
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33
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Youssef OA, Terns RM, Terns MP. Dynamic interactions within sub-complexes of the H/ACA pseudouridylation guide RNP. Nucleic Acids Res 2007; 35:6196-206. [PMID: 17855403 PMCID: PMC2094053 DOI: 10.1093/nar/gkm673] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2007] [Revised: 08/13/2007] [Accepted: 08/16/2007] [Indexed: 12/03/2022] Open
Abstract
H/ACA RNP complexes change uridines to pseudouridines in target non-coding RNAs in eukaryotes and archaea. H/ACA RNPs are comprised of a guide RNA and four essential proteins: Cbf5 (pseudouridine synthase), L7Ae, Gar1 and Nop10 in archaea. The guide RNA captures the target RNA via two antisense elements brought together to form a contiguous binding site within the pseudouridylation pocket (internal loop) of the guide RNA. Cbf5 and L7Ae interact independently with the guide RNA, and here we have examined the impacts of these proteins on the RNA in nucleotide protection assays. The results indicate that the interactions observed in a fully assembled H/ACA RNP are established in the sub-complexes, but also reveal a unique Cbf5-guide RNA interaction that is displaced by L7Ae. In addition, the results indicate that L7Ae binding at the kink (k)-turn of the guide RNA induces the formation of the upper stem, and thus also the pseudouridylation pocket. Our findings indicate that L7Ae is essential for formation of the substrate RNA binding site in the archaeal H/ACA RNP, and suggest that k-turn-binding proteins may remodel partner RNAs with important effects distant from the protein-binding site.
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Affiliation(s)
| | - Rebecca M. Terns
- Departments of Biochemistry and Molecular Biology, and Genetics, University of Georgia, Athens, GA 30602, USA
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34
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Caban K, Kinzy SA, Copeland PR. The L7Ae RNA binding motif is a multifunctional domain required for the ribosome-dependent Sec incorporation activity of Sec insertion sequence binding protein 2. Mol Cell Biol 2007; 27:6350-60. [PMID: 17636016 PMCID: PMC2099609 DOI: 10.1128/mcb.00632-07] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The decoding of specific UGA codons as selenocysteine is specified by the Sec insertion sequence (SECIS) element. Additionally, Sec-tRNA([Ser]Sec) and the dedicated Sec-specific elongation factor eEFSec are required but not sufficient for nonsense suppression. SECIS binding protein 2 (SBP2) is also essential for Sec incorporation, but its precise role is unknown. In addition to binding the SECIS element, SBP2 binds stably and quantitatively to ribosomes. To determine the function of the SBP2-ribosome interaction, conserved amino acids throughout the SBP2 L7Ae RNA binding motif were mutated to alanine in clusters of five. Mutant proteins were analyzed for ribosome binding, SECIS element binding, and Sec incorporation activity, allowing us to identify two distinct but interdependent sites within the L7Ae motif: (i) a core L7Ae motif required for SECIS binding and ribosome binding and (ii) an auxiliary motif involved in physical and functional interactions with the ribosome. Structural modeling of SBP2 based on the 15.5-kDa protein-U4 snRNA complex strongly supports a two-site model for L7Ae domain function within SBP2. These results provide evidence that the SBP2-ribosome interaction is essential for Sec incorporation.
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Affiliation(s)
- Kelvin Caban
- Department of Molecular Genetics, Microbiology and Immunology, UMDNJ-Robert Wood Johnson Medical School, 675 Hoes Lane, Piscataway, NJ 08854, USA
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35
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Papp LV, Lu J, Holmgren A, Khanna KK. From selenium to selenoproteins: synthesis, identity, and their role in human health. Antioxid Redox Signal 2007; 9:775-806. [PMID: 17508906 DOI: 10.1089/ars.2007.1528] [Citation(s) in RCA: 867] [Impact Index Per Article: 51.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
The requirement of the trace element selenium for life and its beneficial role in human health has been known for several decades. This is attributed to low molecular weight selenium compounds, as well as to its presence within at least 25 proteins, named selenoproteins, in the form of the amino acid selenocysteine (Sec). Incorporation of Sec into selenoproteins employs a unique mechanism that involves decoding of the UGA codon. This process requires multiple features such as the selenocysteine insertion sequence (SECIS) element and several protein factors including a specific elongation factor EFSec and the SECIS binding protein 2, SBP2. The function of most selenoproteins is currently unknown; however, thioredoxin reductases (TrxR), glutathione peroxidases (GPx) and thyroid hormone deiodinases (DIO) are well characterised selenoproteins involved in redox regulation of intracellular signalling, redox homeostasis and thyroid hormone metabolism. Recent evidence points to a role for selenium compounds as well as selenoproteins in the prevention of some forms of cancer. A number of clinical trials are either underway or being planned to examine the effects of selenium on cancer incidence. In this review we describe some of the recent progress in our understanding of the mechanism of selenoprotein synthesis, the role of selenoproteins in human health and disease and the therapeutic potential of some of these proteins.
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Affiliation(s)
- Laura Vanda Papp
- Queensland Institute of Medical Research, Cancer and Cell Biology Division, Herston, QLD, Australia
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36
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Cléry A, Bourguignon-Igel V, Allmang C, Krol A, Branlant C. An improved definition of the RNA-binding specificity of SECIS-binding protein 2, an essential component of the selenocysteine incorporation machinery. Nucleic Acids Res 2007; 35:1868-84. [PMID: 17332014 PMCID: PMC1874613 DOI: 10.1093/nar/gkm066] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/02/2022] Open
Abstract
By binding to SECIS elements located in the 3′-UTR of selenoprotein mRNAs, the protein SBP2 plays a key role in the assembly of the selenocysteine incorporation machinery. SBP2 contains an L7Ae/L30 RNA-binding domain similar to that of protein 15.5K/Snu13p, which binds K-turn motifs with a 3-nt bulge loop closed by a tandem of G.A and A.G pairs. Here, by SELEX experiments, we demonstrate the capacity of SBP2 to bind such K-turn motifs with a protruding U residue. However, we show that conversion of the bulge loop into an internal loop reinforces SBP2 affinity and to a greater extent RNP stability. Opposite variations were found for Snu13p. Accordingly, footprinting assays revealed strong contacts of SBP2 with helices I and II and the 5′-strand of the internal loop, as opposed to the loose interaction of Snu13p. Our data also identifies new determinants for SBP2 binding which are located in helix II. Among the L7Ae/L30 family members, these determinants are unique to SBP2. Finally, in accordance with functional data on SECIS elements, the identity of residues at positions 2 and 3 in the loop influences SBP2 affinity. Altogether, the data provide a very precise definition of the SBP2 RNA specificity.
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Affiliation(s)
- A. Cléry
- Laboratoire de Maturation des ARN et Enzymologie Moléculaire – UMR 7567 CNRS-UHP, Nancy Université, Faculté des Sciences et Techniques – BP 239, 54506 Vandoeuvre-lès-Nancy Cedex, France and Architecture et Réactivité de l'arN – CNRS-Université Louis Pasteur, Institut de Biologie Moléculaire et Cellulaire 15 Rue René Descartes, 67084 Strasbourg Cedex, France
| | - V. Bourguignon-Igel
- Laboratoire de Maturation des ARN et Enzymologie Moléculaire – UMR 7567 CNRS-UHP, Nancy Université, Faculté des Sciences et Techniques – BP 239, 54506 Vandoeuvre-lès-Nancy Cedex, France and Architecture et Réactivité de l'arN – CNRS-Université Louis Pasteur, Institut de Biologie Moléculaire et Cellulaire 15 Rue René Descartes, 67084 Strasbourg Cedex, France
| | - C. Allmang
- Laboratoire de Maturation des ARN et Enzymologie Moléculaire – UMR 7567 CNRS-UHP, Nancy Université, Faculté des Sciences et Techniques – BP 239, 54506 Vandoeuvre-lès-Nancy Cedex, France and Architecture et Réactivité de l'arN – CNRS-Université Louis Pasteur, Institut de Biologie Moléculaire et Cellulaire 15 Rue René Descartes, 67084 Strasbourg Cedex, France
| | - A. Krol
- Laboratoire de Maturation des ARN et Enzymologie Moléculaire – UMR 7567 CNRS-UHP, Nancy Université, Faculté des Sciences et Techniques – BP 239, 54506 Vandoeuvre-lès-Nancy Cedex, France and Architecture et Réactivité de l'arN – CNRS-Université Louis Pasteur, Institut de Biologie Moléculaire et Cellulaire 15 Rue René Descartes, 67084 Strasbourg Cedex, France
| | - C. Branlant
- Laboratoire de Maturation des ARN et Enzymologie Moléculaire – UMR 7567 CNRS-UHP, Nancy Université, Faculté des Sciences et Techniques – BP 239, 54506 Vandoeuvre-lès-Nancy Cedex, France and Architecture et Réactivité de l'arN – CNRS-Université Louis Pasteur, Institut de Biologie Moléculaire et Cellulaire 15 Rue René Descartes, 67084 Strasbourg Cedex, France
- *To whom the correspondence should be addressed. 33 38368430333 383684307
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37
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Liu J, Lilley DMJ. The role of specific 2'-hydroxyl groups in the stabilization of the folded conformation of kink-turn RNA. RNA (NEW YORK, N.Y.) 2007; 13:200-10. [PMID: 17158708 PMCID: PMC1781366 DOI: 10.1261/rna.285707] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/12/2023]
Abstract
The role of 2'-hydroxyl groups in stabilizing the tightly kinked geometry of the kink-turn (K-turn) has been investigated. Individual 2'-OH groups have been removed by chemical synthesis, and the kinking of the RNA has been studied by gel electrophoresis and fluorescence resonance energy transfer. The results have been analyzed by reference to a database of 11 different crystallographic structures of K-turns. The potential hydrogen bonds fall into several classes. The most important are those in the core of the turn and ribose-phosphate interactions around the bulge. Of these the single most important hydrogen bond is one donated from the 2'-OH of the 5' nucleotide of the bulge to the N1 of the adenine of the kink-proximal A*G pair. This is present in all known K-turn structures, and removal of the 2'-OH completely prevents metal ion-induced folding. Hydrogen bonds formed in the minor grooves of the helical stems are less important, and removal of the participating 2'-OH groups leads to reduced impairment of folding. These interactions are generally more polymorphic, and hydrogen bonds probably form where possible, as permitted by the global structure.
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Affiliation(s)
- Jia Liu
- Cancer Research UK Nucleic Acid Structure Research Group, The University of Dundee, UK
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38
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Cléry A, Senty-Ségault V, Leclerc F, Raué HA, Branlant C. Analysis of sequence and structural features that identify the B/C motif of U3 small nucleolar RNA as the recognition site for the Snu13p-Rrp9p protein pair. Mol Cell Biol 2006; 27:1191-206. [PMID: 17145781 PMCID: PMC1800722 DOI: 10.1128/mcb.01287-06] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
The eukaryal Snu13p/15.5K protein binds K-turn motifs in U4 snRNA and snoRNAs. Two Snu13p/15.5K molecules bind the nucleolar U3 snoRNA required for the early steps of preribosomal processing. Binding of one molecule on the C'/D motif allows association of proteins Nop1p, Nop56p, and Nop58p, whereas binding of the second molecule on the B/C motif allows Rrp9p recruitment. To understand how the Snu13p-Rrp9p pair recognizes the B/C motif, we first improved the identification of RNA determinants required for Snu13p binding by experiments using the systematic evolution of ligands by exponential enrichment. This demonstrated the importance of a U.U pair stacked on the sheared pairs and revealed a direct link between Snu13p affinity and the stability of helices I and II. Sequence and structure requirements for efficient association of Rrp9p on the B/C motif were studied in yeast cells by expression of variant U3 snoRNAs and immunoselection assays. A G-C pair in stem II, a G residue at position 1 in the bulge, and a short stem I were found to be required. The data identify the in vivo function of most of the conserved residues of the U3 snoRNA B/C motif. They bring important information to understand how different K-turn motifs can recruit different sets of proteins after Snu13p association.
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Affiliation(s)
- A Cléry
- Laboratoire de Maturation des ARN et Enzymologie Moléculaire, UMR 7567, Université Henri Poincaré, Nancy I, BP 239, 54506 Vandoeuvre-lès-Nancy, France.
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Allmang C, Krol A. Selenoprotein synthesis: UGA does not end the story. Biochimie 2006; 88:1561-71. [PMID: 16737768 DOI: 10.1016/j.biochi.2006.04.015] [Citation(s) in RCA: 109] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2006] [Accepted: 04/24/2006] [Indexed: 11/15/2022]
Abstract
It is well established that the beneficial effects of the trace element selenium are mediated by its major biological product, the amino acid selenocysteine, present in the active site of selenoproteins. These fulfill different functions, as varied as oxidation-reduction of metabolites in bacteria, reduction of reactive oxygen species, control of the redox status of the cell or thyroid hormone maturation. This review will focus on the singularities of the selenocysteine biosynthesis pathway and its unique incorporation mechanism into eukaryal selenoproteins. Selenocysteine biosynthesis from serine is achieved on tRNA(Sec) and requires four proteins. As this amino acid is encoded by an in-frame UGA codon, otherwise signaling termination of translation, ribosomes must be told not to stop at this position in the mRNA. Several molecular partners acting in cis or in trans have been identified, but their knowledge has not enabled yet to firmly establish the molecular events underlying this mechanism. Data suggest that other, so far uncharacterized factors might exist. In this survey, we attempted to compile all the data available in the literature and to describe the latest developments in the field.
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Affiliation(s)
- C Allmang
- Institut de Biologie Moléculaire et Cellulaire, UPR 9002 du CNRS Architecture et Réactivité de l'ARN. Université Louis-Pasteur, 15, rue René-Descartes, 67084 Strasbourg Cedex, France
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40
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Papp LV, Lu J, Striebel F, Kennedy D, Holmgren A, Khanna KK. The redox state of SECIS binding protein 2 controls its localization and selenocysteine incorporation function. Mol Cell Biol 2006; 26:4895-910. [PMID: 16782878 PMCID: PMC1489162 DOI: 10.1128/mcb.02284-05] [Citation(s) in RCA: 86] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2005] [Revised: 12/21/2005] [Accepted: 04/15/2006] [Indexed: 11/20/2022] Open
Abstract
Selenoproteins are central controllers of cellular redox homeostasis. Incorporation of selenocysteine (Sec) into selenoproteins employs a unique mechanism to decode the UGA stop codon. The process requires the Sec insertion sequence (SECIS) element, tRNASec, and protein factors including the SECIS binding protein 2 (SBP2). Here, we report the characterization of motifs within SBP2 that regulate its subcellular localization and function. We show that SBP2 shuttles between the nucleus and the cytoplasm via intrinsic, functional nuclear localization signal and nuclear export signal motifs and that its nuclear export is dependent on the CRM1 pathway. Oxidative stress induces nuclear accumulation of SBP2 via oxidation of cysteine residues within a redox-sensitive cysteine-rich domain. These modifications are efficiently reversed in vitro by human thioredoxin and glutaredoxin, suggesting that these antioxidant systems might regulate redox status of SBP2 in vivo. Depletion of SBP2 in cell lines using small interfering RNA results in a decrease in Sec incorporation, providing direct evidence for its requirement for selenoprotein synthesis. Furthermore, Sec incorporation is reduced substantially after treatment of cells with agents that cause oxidative stress, suggesting that nuclear sequestration of SBP2 under such conditions may represent a mechanism to regulate the expression of selenoproteins.
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Affiliation(s)
- Laura V Papp
- Queensland Institute of Medical Research, 300 Herston Road, Herston, Queensland 4029, Australia
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41
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Allamand V, Richard P, Lescure A, Ledeuil C, Desjardin D, Petit N, Gartioux C, Ferreiro A, Krol A, Pellegrini N, Urtizberea JA, Guicheney P. A single homozygous point mutation in a 3'untranslated region motif of selenoprotein N mRNA causes SEPN1-related myopathy. EMBO Rep 2006; 7:450-4. [PMID: 16498447 PMCID: PMC1456920 DOI: 10.1038/sj.embor.7400648] [Citation(s) in RCA: 80] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2005] [Revised: 12/20/2005] [Accepted: 01/23/2006] [Indexed: 11/08/2022] Open
Abstract
Mutations in the SEPN1 gene encoding the selenoprotein N (SelN) have been described in different congenital myopathies. Here, we report the first mutation in the selenocysteine insertion sequence (SECIS) of SelN messenger RNA, a hairpin structure located in the 3' untranslated region, in a patient presenting a classical although mild form of rigid spine muscular dystrophy. We detected a significant reduction in both mRNA and protein levels in the patient's skin fibroblasts. The SECIS element is crucial for the insertion of selenocysteine at the reprogrammed UGA codon by recruiting the SECIS-binding protein 2 (SBP2), and we demonstrated that this mutation abolishes SBP2 binding to SECIS in vitro, thereby preventing co-translational incorporation of selenocysteine and SelN synthesis. The identification of this mutation affecting a conserved base in the SECIS functional motif thereby reveals the structural basis for a novel pathological mechanism leading to SEPN1-related myopathy.
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Affiliation(s)
- Valérie Allamand
- Institut National de la Santé et de la Recherche Médicale, U582, Institut de Myologie, IFR 14, Groupe Hospitalier Pitié-Salpêtrière, Paris, France.
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42
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Abstract
This review focuses on the known factors required for selenocysteine (Sec) incorporation in eukaryotes and highlights recent findings that have compelled us to propose a new model for the mechanism of Sec incorporation. In light of this data we also review the controversial aspects of the previous model specifically regarding the proposed interaction between SBP2 and eEFSec. In addition, the relevance of two recently discovered factors in the recoding of Sec are reviewed. The role of the ribosome in this process is emphasized along with a detailed analysis of kinkturn structures present in the ribosome and the L7Ae RNA-binding motif present in SBP2 and other proteins.
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Affiliation(s)
- K. Caban
- Department of Molecular Genetics, Microbiology and Immunology, UMDNJ-Robert Wood Johnson Medical School, 675 Hoes Lane, Piscataway, New Jersey 08854 USA
| | - P. R. Copeland
- Department of Molecular Genetics, Microbiology and Immunology, UMDNJ-Robert Wood Johnson Medical School, 675 Hoes Lane, Piscataway, New Jersey 08854 USA
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43
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Dennis PP, Omer A. Small non-coding RNAs in Archaea. Curr Opin Microbiol 2005; 8:685-94. [PMID: 16256421 DOI: 10.1016/j.mib.2005.10.013] [Citation(s) in RCA: 84] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2005] [Accepted: 10/12/2005] [Indexed: 10/25/2022]
Abstract
Biochemical and informatics analyses conducted over the past few years have revealed the presence of a plethora of small non-coding RNAs in various species of Archaea. A large proportion of these RNAs contain a common structural motif called the RNA kink turn (K-turn). The best-characterized are the C/D box and the H/ACA box guide small (s)RNAs. Both contain the K-turn fold and require the binding of the L7Ae protein to stabilize the structure of this crucial motif. These sRNAs assemble with L7Ae and several other proteins into complex and dynamic ribonucleoprotein machines that mediate guide-directed ribose methylation or pseudouridylation to specific locations in ribosomal or transfer RNA. Analyses of new archaeal sRNA libraries have identified additional classes of novel sRNAs; many of these contain the RNA K-turn motif and suggest that the RNAs might function as ribonucleoprotein complexes. Some have characteristics of small interfering RNAs or of micro RNAs that have been implicated in the post-transcriptional control of gene expression, whereas others appear to be involved in protein translocation or in ribosomal RNA processing and ribosome assembly. A complete understanding of the structure of the K-turn motif and its contribution to various RNA-RNA and RNA-protein interactions will be absolutely essential to fully elucidate the biological organization, activity and function of these novel archaeal ribonucleoprotein machines.
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Affiliation(s)
- Patrick P Dennis
- The Division of Molecular and Cellular Biosciences, National Science Foundation, 4201 Wilson Blvd., Arlington, VA 22230, USA
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Kinzy SA, Caban K, Copeland PR. Characterization of the SECIS binding protein 2 complex required for the co-translational insertion of selenocysteine in mammals. Nucleic Acids Res 2005; 33:5172-80. [PMID: 16155186 PMCID: PMC1214547 DOI: 10.1093/nar/gki826] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Selenocysteine is incorporated into at least 25 human proteins by a complex mechanism that is a unique modification of canonical translation elongation. Selenocysteine incorporation requires the concerted action of a kink-turn structural RNA (SECIS) element in the 3′ untranslated region of each selenoprotein mRNA, a selenocysteine-specific translation elongation factor (eEFSec) and a SECIS binding protein (SBP2). Here, we analyze the molecular context in which SBP2 functions. Contrary to previous findings, a combination of gel filtration chromatography and co-purification studies demonstrates that SBP2 does not self-associate. However, SBP2 is found to be quantitatively associated with ribosomes. Interestingly, a wild-type but not mutant SECIS element is able to effectively compete with the SBP2 ribosome interaction, indicating that SBP2 cannot simultaneously interact with the ribosome and the SECIS element. This data also supports the hypothesis that SBP2 interacts with one or more kink turns on 28S rRNA. Based on these results, we propose a revised model for selenocysteine incorporation where SBP2 remains ribosome bound except during selenocysteine delivery to the ribosomal A-site.
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Affiliation(s)
| | | | - Paul R. Copeland
- To whom correspondence should be addressed. Tel: +732 235 4670; Fax: +732 235 5223;
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45
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Turner B, Melcher SE, Wilson TJ, Norman DG, Lilley DMJ. Induced fit of RNA on binding the L7Ae protein to the kink-turn motif. RNA (NEW YORK, N.Y.) 2005; 11:1192-200. [PMID: 15987806 PMCID: PMC1370803 DOI: 10.1261/rna.2680605] [Citation(s) in RCA: 63] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Abstract
The kink-turn is a widespread motif in RNA consisting of a three-nucleotide bulge flanked on one side by consecutive A3G mismatches. Important examples are found in the ribosome, U4 RNA, and in snoRNAs involved in RNA modification. The motif is a common protein binding site, and the RNA has been found to adopt a tightly kinked conformation in crystal structures. However, in free solution there is a dynamic exchange between kinked and extended conformations, with the equilibrium driven toward the kinked form by the addition of metal ions. Here we used fluorescence resonance energy transfer (FRET) to show that the L7Ae protein of Archaeoglobus fulgidus binds to RNA containing a kink-turn with nanomolar affinity, and induces folding into the tightly kinked conformation even in the absence of metal ions. Thus this RNA may act as a relatively flexible hinge during RNA folding, until fixed into its ultimate kinked structure by the binding of L7 or related protein.
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Affiliation(s)
- Ben Turner
- Cancer Research-UK Nucleic Acid Structure Research Group, MSI/WTB Complex, The University of Dundee, Dundee DD1 5EH, UK
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46
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Russo G, Cuccurese M, Monti G, Russo A, Amoresano A, Pucci P, Pietropaolo C. Ribosomal protein L7a binds RNA through two distinct RNA-binding domains. Biochem J 2005; 385:289-99. [PMID: 15361074 PMCID: PMC1134697 DOI: 10.1042/bj20040371] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
The human ribosomal protein L7a is a component of the major ribosomal subunit. We previously identified three nuclear-localization-competent domains within L7a, and demonstrated that the domain defined by aa (amino acids) 52-100 is necessary, although not sufficient, to target the L7a protein to the nucleoli. We now demonstrate that L7a interacts in vitro with a presumably G-rich RNA structure, which has yet to be defined. We also demonstrate that the L7a protein contains two RNA-binding domains: one encompassing aa 52-100 (RNAB1) and the other encompassing aa 101-161 (RNAB2). RNAB1 does not contain any known nucleic-acid-binding motif, and may thus represent a new class of such motifs. On the other hand, a specific region of RNAB2 is highly conserved in several other protein components of the ribonucleoprotein complex. We have investigated the topology of the L7a-RNA complex using a recombinant form of the protein domain that encompasses residues 101-161 and a 30mer poly(G) oligonucleotide. Limited proteolysis and cross-linking experiments, and mass spectral analyses of the recombinant protein domain and its complex with poly(G) revealed the RNA-binding region.
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Affiliation(s)
- Giulia Russo
- *Dipartimento di Biochimica e Biotecnologie Mediche, Università Federico II, Via Sergio Pansini 5 Napoli, I-80131 Italy
| | - Monica Cuccurese
- *Dipartimento di Biochimica e Biotecnologie Mediche, Università Federico II, Via Sergio Pansini 5 Napoli, I-80131 Italy
| | - Gianluca Monti
- †Dipartimento di Chimica Organica e Biologica, Università Federico II, Complesso Universitario Monte S. Angelo, Via Cinthia 4, I-80126 Italy
| | - Annapina Russo
- *Dipartimento di Biochimica e Biotecnologie Mediche, Università Federico II, Via Sergio Pansini 5 Napoli, I-80131 Italy
| | - Angela Amoresano
- †Dipartimento di Chimica Organica e Biologica, Università Federico II, Complesso Universitario Monte S. Angelo, Via Cinthia 4, I-80126 Italy
| | - Pietro Pucci
- †Dipartimento di Chimica Organica e Biologica, Università Federico II, Complesso Universitario Monte S. Angelo, Via Cinthia 4, I-80126 Italy
- ‡CEINGE Biotecnologie Avanzate S.C.a.r.l., Via Comunale Margherita 482 Napoli, I-80145 Italy
| | - Concetta Pietropaolo
- *Dipartimento di Biochimica e Biotecnologie Mediche, Università Federico II, Via Sergio Pansini 5 Napoli, I-80131 Italy
- To whom correspondence should be addressed (email )
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Howard MT, Aggarwal G, Anderson CB, Khatri S, Flanigan KM, Atkins JF. Recoding elements located adjacent to a subset of eukaryal selenocysteine-specifying UGA codons. EMBO J 2005; 24:1596-607. [PMID: 15791204 PMCID: PMC1142574 DOI: 10.1038/sj.emboj.7600642] [Citation(s) in RCA: 81] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2005] [Accepted: 03/07/2005] [Indexed: 11/09/2022] Open
Abstract
Incorporation of the 21st amino acid, selenocysteine, into proteins is specified in all three domains of life by dynamic translational redefinition of UGA codons. In eukarya and archaea, selenocysteine insertion requires a cis-acting selenocysteine insertion sequence (SECIS) usually located in the 3'UTR of selenoprotein mRNAs. Here we present comparative sequence analysis and experimental data supporting the presence of a second stop codon redefinition element located adjacent to a selenocysteine-encoding UGA codon in the eukaryal gene, SEPN1. This element is sufficient to stimulate high-level (6%) translational redefinition of the SEPN1 UGA codon in human cells. Readthrough levels further increased to 12% when tested in the presence of the SEPN1 3'UTR SECIS. Directed mutagenesis and phylogeny of the sequence context strongly supports the importance of a stem loop starting six nucleotides 3' of the UGA codon. Sequences capable of forming strong RNA structures were also identified 3' adjacent to, or near, selenocysteine-encoding UGA codons in the Sps2, SelH, SelO, and SelT selenoprotein genes.
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Affiliation(s)
- Michael T Howard
- Department of Human Genetics, University of Utah, Salt Lake City, UT 84112, USA.
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48
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Leibundgut M, Frick C, Thanbichler M, Böck A, Ban N. Selenocysteine tRNA-specific elongation factor SelB is a structural chimaera of elongation and initiation factors. EMBO J 2004; 24:11-22. [PMID: 15616587 PMCID: PMC544917 DOI: 10.1038/sj.emboj.7600505] [Citation(s) in RCA: 90] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2004] [Accepted: 11/12/2004] [Indexed: 11/08/2022] Open
Abstract
In all three kingdoms of life, SelB is a specialized translation elongation factor responsible for the cotranslational incorporation of selenocysteine into proteins by recoding of a UGA stop codon in the presence of a downstream mRNA hairpin loop. Here, we present the X-ray structures of SelB from the archaeon Methanococcus maripaludis in the apo-, GDP- and GppNHp-bound form and use mutational analysis to investigate the role of individual amino acids in its aminoacyl-binding pocket. All three SelB structures reveal an EF-Tu:GTP-like domain arrangement. Upon binding of the GTP analogue GppNHp, a conformational change of the Switch 2 region in the GTPase domain leads to the exposure of SelB residues involved in clamping the 5' phosphate of the tRNA. A conserved extended loop in domain III of SelB may be responsible for specific interactions with tRNA(Sec) and act as a ruler for measuring the extra long acceptor arm. Domain IV of SelB adopts a beta barrel fold and is flexibly tethered to domain III. The overall domain arrangement of SelB resembles a 'chalice' observed so far only for initiation factor IF2/eIF5B. In our model of SelB bound to the ribosome, domain IV points towards the 3' mRNA entrance cleft ready to interact with the downstream secondary structure element.
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Affiliation(s)
- Marc Leibundgut
- Institut für Molekularbiologie und Biophysik, Eidgenössische Technische Hochschule Zürich, Zürich, Switzerland
| | - Christian Frick
- Institut für Molekularbiologie und Biophysik, Eidgenössische Technische Hochschule Zürich, Zürich, Switzerland
| | | | - August Böck
- Departement Biologie I der Universität München, München, Germany
| | - Nenad Ban
- Institut für Molekularbiologie und Biophysik, Eidgenössische Technische Hochschule Zürich, Zürich, Switzerland
- Institute for Molecular Biology and Biophyiscs, Swiss Federal Institute of Technology, ETH Hönggerberg, HPK Building, Zurich, Switzerland. Tel.: +41 1 633 2785; Fax: +41 1 633 1246; E-mail:
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49
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Mehta A, Rebsch CM, Kinzy SA, Fletcher JE, Copeland PR. Efficiency of mammalian selenocysteine incorporation. J Biol Chem 2004; 279:37852-9. [PMID: 15229221 PMCID: PMC2820281 DOI: 10.1074/jbc.m404639200] [Citation(s) in RCA: 78] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Five components have thus far been identified that are necessary for the incorporation of selenocysteine (Sec) into approximately 25 mammalian proteins. Two of these are cis sequences, a SECIS element in the 3'-untranslated region and a Sec codon (UGA) in the coding region. The three known trans-acting factors are a Sec-specific translation elongation factor (eEFSec), the Sec-tRNA(Sec), and a SECIS-binding protein, SBP2. Here we describe a system in which the efficiency of Sec incorporation was determined quantitatively both in vitro and in transfected cells, and in which the contribution of each of the known factors is examined. The efficiency of Sec incorporation into a luciferase reporter system in vitro is maximally 5-8%, which is 6-10 times higher than that in transfected rat hepatoma cells, McArdle 7777. In contrast, the efficiency of Sec incorporation into selenoprotein P in vitro is approximately 40%, suggesting that as yet unidentified cis-elements may regulate differential selenoprotein expression. In addition, we have found that SBP2 is the only limiting factor in rabbit reticulocyte lysate but not in transfected rat hepatoma cells where SBP2 is found to be mostly if not entirely cytoplasmic despite having a strong putative nuclear localization signal. The significance of these findings with regard to the function of known Sec incorporation factors is discussed.
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Affiliation(s)
- Anupama Mehta
- Department of Molecular Genetics, Microbiology and Immunology, University of Medicine and Dentistry of New Jersey Robert Wood Johnson Medical School, Piscataway, New Jersey 08854
| | - Cheryl M. Rebsch
- Department of Molecular Genetics, Microbiology and Immunology, University of Medicine and Dentistry of New Jersey Robert Wood Johnson Medical School, Piscataway, New Jersey 08854
| | - Scott A. Kinzy
- Department of Molecular Genetics, Microbiology and Immunology, University of Medicine and Dentistry of New Jersey Robert Wood Johnson Medical School, Piscataway, New Jersey 08854
| | - Julia E. Fletcher
- Department of Cell Biology, Lerner Research Institute, Cleveland Clinic Foundation, Cleveland, Ohio 44195
| | - Paul R. Copeland
- Department of Molecular Genetics, Microbiology and Immunology, University of Medicine and Dentistry of New Jersey Robert Wood Johnson Medical School, Piscataway, New Jersey 08854
- To whom correspondence should be addressed: Dept. of Molecular Genetics, Microbiology and Immunology, UMDNJ Robert Wood Johnson Medical School, 675 Hoes Lane, Rm. 728, Piscataway, NJ 08854. Tel.: 732-235-4670; Fax: 732-235-5223;
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50
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Ramos A, Lane AN, Hollingworth D, Fan TWM. Secondary structure and stability of the selenocysteine insertion sequences (SECIS) for human thioredoxin reductase and glutathione peroxidase. Nucleic Acids Res 2004; 32:1746-55. [PMID: 15026534 PMCID: PMC390329 DOI: 10.1093/nar/gkh331] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
We have used high resolution NMR and thermodynamics to characterize the secondary structure and stability of the selenocysteine insertion sequences (SECIS) of human glutathione peroxidase (58 nt) and thioredoxin reductase (51 nt). These sequences are members of the two classes of SECIS recently identified with two distinct structures capable of directing selenocysteine incorporation into proteins in eukaryotes. UV melting experiments showed a single cooperative and reversible transition for each RNA, which indicates the presence of stable secondary structures. Despite their large size, the RNAs gave well resolved NMR spectra for the exchangeable protons. Using NOESY, the imino protons as well as the cytosine amino protons of all of the Watson-Crick base pairs were assigned. In addition, a number of non-canonical base pairs including the wobble G.U pairs were identified. The interbase-pair NOEs allowed definition of the hydrogen-bonded structure of the oligonucleotides, providing an experimental model of the secondary structure of these elements. The derived secondary structures are consistent with several features of the predicted models, but with some important differences, especially regarding the conserved sequence motifs.
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Affiliation(s)
- Andres Ramos
- Division of Molecular Structure, National Institute for Medical Research, The Ridgeway, Mill Hill, London NW7 1AA, UK
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