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de Oliveira J, Denadai MB, Costa DL. Crosstalk between Heme Oxygenase-1 and Iron Metabolism in Macrophages: Implications for the Modulation of Inflammation and Immunity. Antioxidants (Basel) 2022; 11:861. [PMID: 35624725 PMCID: PMC9137896 DOI: 10.3390/antiox11050861] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2022] [Revised: 04/21/2022] [Accepted: 04/22/2022] [Indexed: 12/16/2022] Open
Abstract
Heme oxygenase-1 (HO-1) is an enzyme that catalyzes the degradation of heme, releasing equimolar amounts of carbon monoxide (CO), biliverdin (BV), and iron. The anti-inflammatory and antioxidant properties of HO-1 activity are conferred in part by the release of CO and BV and are extensively characterized. However, iron constitutes an important product of HO-1 activity involved in the regulation of several cellular biological processes. The macrophage-mediated recycling of heme molecules, in particular those contained in hemoglobin, constitutes the major mechanism through which living organisms acquire iron. This process is finely regulated by the activities of HO-1 and of the iron exporter protein ferroportin. The expression of both proteins can be induced or suppressed in response to pro- and anti-inflammatory stimuli in macrophages from different tissues, which alters the intracellular iron concentrations of these cells. As we discuss in this review article, changes in intracellular iron levels play important roles in the regulation of cellular oxidation reactions as well as in the transcriptional and translational regulation of the expression of proteins related to inflammation and immune responses, and therefore, iron metabolism represents a potential target for the development of novel therapeutic strategies focused on the modulation of immunity and inflammation.
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Affiliation(s)
- Joseana de Oliveira
- Departamento de Bioquímica e Imunologia, Faculdade de Medicina de Ribeirão Preto, Universidade de São Paulo, Ribeirao Preto 14049-900, Brazil; (J.d.O.); (M.B.D.)
- Programa de Pós-Graduação em Imunologia Básica e Aplicada, Faculdade de Medicina de Ribeirão Preto, Universidade de São Paulo, Ribeirao Preto 14049-900, Brazil
| | - Marina B. Denadai
- Departamento de Bioquímica e Imunologia, Faculdade de Medicina de Ribeirão Preto, Universidade de São Paulo, Ribeirao Preto 14049-900, Brazil; (J.d.O.); (M.B.D.)
- Programa de Pós-Graduação em Imunologia Básica e Aplicada, Faculdade de Medicina de Ribeirão Preto, Universidade de São Paulo, Ribeirao Preto 14049-900, Brazil
| | - Diego L. Costa
- Departamento de Bioquímica e Imunologia, Faculdade de Medicina de Ribeirão Preto, Universidade de São Paulo, Ribeirao Preto 14049-900, Brazil; (J.d.O.); (M.B.D.)
- Programa de Pós-Graduação em Imunologia Básica e Aplicada, Faculdade de Medicina de Ribeirão Preto, Universidade de São Paulo, Ribeirao Preto 14049-900, Brazil
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Liu X, Hou Y, Chen S, Liu J. Controlling dopamine binding by the new aptamer for a FRET-based biosensor. Biosens Bioelectron 2020; 173:112798. [PMID: 33197768 DOI: 10.1016/j.bios.2020.112798] [Citation(s) in RCA: 29] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2020] [Revised: 10/19/2020] [Accepted: 11/02/2020] [Indexed: 12/11/2022]
Abstract
Dopamine is one of the most important neurotransmitters. A high-quality DNA aptamer for dopamine was reported in 2018. However, fundamental understanding of its binding and folding is lacking, which is critical for related biosensor design. Herein, we performed careful assays using a label-free technique called isothermal titration calorimetry (ITC) to study its secondary structure. We divided this aptamer into four regions and individually examined each of them. We confirmed two stems, but the third stem is believed to be part of a loop. The aptamer was then truncated. The original aptamer had a Kd of 2.2 ± 0.3 μM at 25 °C. Shortening the structure by one or two base pairs increased the Kd to 6.9 and 44.4 μM, respectively. Dopamine binding was promoted by both increasing the Mg2+ concentration and decreasing the temperature. At 5 °C, a Kd of 0.4 μM was achieved. Based on this understanding, we designed two fluorescence resonance energy transfer (FRET) quenching biosensors that differ only by a base pair. The shorter sensor had 3-fold higher sensitivity and a detection limit of 0.9 μM. In 1% fetal bovine serum, the sensor retained a similar limit of detection of 1.14 μM. A two-fluorophore ratiometric FRET sensor was also demonstrated with a low detection limit of 0.12 μM. This work indicated the feasibility of designing folding-based sensors for dopamine, and this design can be extended to other sensing modalities such as electrochemistry and colorimetry.
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Affiliation(s)
- Xixia Liu
- Hubei Key Laboratory of Edible Wild Plants Conservation and Utilization, Hubei Normal University, Huangshi, Hubei province, 435002, China; Department of Chemistry, and Waterloo Institute for Nanotechnology, University of Waterloo, Waterloo, ON, N2L 3G1, Canada
| | - Yaoyao Hou
- Hubei Key Laboratory of Edible Wild Plants Conservation and Utilization, Hubei Normal University, Huangshi, Hubei province, 435002, China
| | - Sirui Chen
- Hubei Key Laboratory of Edible Wild Plants Conservation and Utilization, Hubei Normal University, Huangshi, Hubei province, 435002, China
| | - Juewen Liu
- Department of Chemistry, and Waterloo Institute for Nanotechnology, University of Waterloo, Waterloo, ON, N2L 3G1, Canada.
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Sukhbaatar N, Weichhart T. Iron Regulation: Macrophages in Control. Pharmaceuticals (Basel) 2018; 11:ph11040137. [PMID: 30558109 PMCID: PMC6316009 DOI: 10.3390/ph11040137] [Citation(s) in RCA: 105] [Impact Index Per Article: 17.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2018] [Revised: 12/10/2018] [Accepted: 12/12/2018] [Indexed: 12/21/2022] Open
Abstract
Macrophages are sentinel cells of the innate immune system and have important functions in development, tissue homeostasis, and immunity. These phylogenetically ancient cells also developed a variety of mechanisms to control erythropoiesis and the handling of iron. Red pulp macrophages in the spleen, Kupffer cells in the liver, and central nurse macrophages in the bone marrow ensure a coordinated metabolism of iron to support erythropoiesis. Phagocytosis of senescent red blood cells by macrophages in the spleen and the liver provide a continuous delivery of recycled iron under steady-state conditions and during anemic stress. Central nurse macrophages in the bone marrow utilize this iron and provide a cellular scaffold and niche to promote differentiation of erythroblasts. This review focuses on the role of the distinct macrophage populations that contribute to efficient iron metabolism and highlight important cellular and systemic mechanisms involved in iron-regulating processes.
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Affiliation(s)
- Nyamdelger Sukhbaatar
- Medical University of Vienna, Center for Pathobiochemistry and Genetics, Vienna 1090, Austria.
| | - Thomas Weichhart
- Medical University of Vienna, Center for Pathobiochemistry and Genetics, Vienna 1090, Austria.
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Arias-Carrasco R, Vásquez-Morán Y, Nakaya HI, Maracaja-Coutinho V. StructRNAfinder: an automated pipeline and web server for RNA families prediction. BMC Bioinformatics 2018; 19:55. [PMID: 29454313 PMCID: PMC5816368 DOI: 10.1186/s12859-018-2052-2] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2017] [Accepted: 02/02/2018] [Indexed: 01/11/2023] Open
Abstract
Background The function of many noncoding RNAs (ncRNAs) depend upon their secondary structures. Over the last decades, several methodologies have been developed to predict such structures or to use them to functionally annotate RNAs into RNA families. However, to fully perform this analysis, researchers should utilize multiple tools, which require the constant parsing and processing of several intermediate files. This makes the large-scale prediction and annotation of RNAs a daunting task even to researchers with good computational or bioinformatics skills. Results We present an automated pipeline named StructRNAfinder that predicts and annotates RNA families in transcript or genome sequences. This single tool not only displays the sequence/structural consensus alignments for each RNA family, according to Rfam database but also provides a taxonomic overview for each assigned functional RNA. Moreover, we implemented a user-friendly web service that allows researchers to upload their own nucleotide sequences in order to perform the whole analysis. Finally, we provided a stand-alone version of StructRNAfinder to be used in large-scale projects. The tool was developed under GNU General Public License (GPLv3) and is freely available at http://structrnafinder.integrativebioinformatics.me. Conclusions The main advantage of StructRNAfinder relies on the large-scale processing and integrating the data obtained by each tool and database employed along the workflow, of which several files are generated and displayed in user-friendly reports, useful for downstream analyses and data exploration. Electronic supplementary material The online version of this article (10.1186/s12859-018-2052-2) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Raúl Arias-Carrasco
- Centro de Genómica y Bioinformática, Facultad de Ciencias, Universidad Mayor, 8580745, Santiago, Chile.,Programa de Doctorado en Genómica Integrativa, Vicerrectoría de Investigación, Universidad Mayor, 8580745, Santiago, Chile
| | - Yessenia Vásquez-Morán
- Centro de Genómica y Bioinformática, Facultad de Ciencias, Universidad Mayor, 8580745, Santiago, Chile
| | - Helder I Nakaya
- Faculdade de Ciências Farmacêuticas, Universidade de São Paulo, São Paulo, 05508-900, Brazil.
| | - Vinicius Maracaja-Coutinho
- Centro de Genómica y Bioinformática, Facultad de Ciencias, Universidad Mayor, 8580745, Santiago, Chile. .,Instituto Vandique, João Pessoa, 58000-000, Brazil. .,Beagle Bioinformatics, 8320000, Santiago, Chile. .,Advanced Center for Chronic Diseases (ACCDiS), Facultad de Ciencias Químicas y Farmacéuticas, Universidad de Chile, 8380492, Santiago, Chile.
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Wilkinson N, Pantopoulos K. The IRP/IRE system in vivo: insights from mouse models. Front Pharmacol 2014; 5:176. [PMID: 25120486 PMCID: PMC4112806 DOI: 10.3389/fphar.2014.00176] [Citation(s) in RCA: 224] [Impact Index Per Article: 22.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2014] [Accepted: 07/07/2014] [Indexed: 12/16/2022] Open
Abstract
Iron regulatory proteins 1 and 2 (IRP1 and IRP2) post-transcriptionally control the expression of several mRNAs encoding proteins of iron, oxygen and energy metabolism. The mechanism involves their binding to iron responsive elements (IREs) in the untranslated regions of target mRNAs, thereby controlling mRNA translation or stability. Whereas IRP2 functions solely as an RNA-binding protein, IRP1 operates as either an RNA-binding protein or a cytosolic aconitase. Early experiments in cultured cells established a crucial role of IRPs in regulation of cellular iron metabolism. More recently, studies in mouse models with global or localized Irp1 and/or Irp2 deficiencies uncovered new physiological functions of IRPs in the context of systemic iron homeostasis. Thus, IRP1 emerged as a key regulator of erythropoiesis and iron absorption by controlling hypoxia inducible factor 2α (HIF2α) mRNA translation, while IRP2 appears to dominate the control of iron uptake and heme biosynthesis in erythroid progenitor cells by regulating the expression of transferrin receptor 1 (TfR1) and 5-aminolevulinic acid synthase 2 (ALAS2) mRNAs, respectively. Targeted disruption of either Irp1 or Irp2 in mice is associated with distinct phenotypic abnormalities. Thus, Irp1(-/-) mice develop polycythemia and pulmonary hypertension, while Irp2(-/-) mice present with microcytic anemia, iron overload in the intestine and the liver, and neurologic defects. Combined disruption of both Irp1 and Irp2 is incombatible with life and leads to early embryonic lethality. Mice with intestinal- or liver-specific disruption of both Irps are viable at birth but die later on due to malabsorption or liver failure, respectively. Adult mice lacking both Irps in the intestine exhibit a profound defect in dietary iron absorption due to a "mucosal block" that is caused by the de-repression of ferritin mRNA translation. Herein, we discuss the physiological function of the IRE/IRP regulatory system.
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Affiliation(s)
- Nicole Wilkinson
- Lady Davis Institute for Medical Research, Jewish General Hospital, and Department of Medicine, McGill University Montreal, QC, Canada
| | - Kostas Pantopoulos
- Lady Davis Institute for Medical Research, Jewish General Hospital, and Department of Medicine, McGill University Montreal, QC, Canada
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Truong NT, Moncion A, Barouki R, Beaune P, de Waziers I. Regulatory sequence responsible for insulin destabilization of cytochrome P450 2B1 (CYP2B1) mRNA. Biochem J 2009; 388:227-35. [PMID: 15617513 PMCID: PMC1186711 DOI: 10.1042/bj20041510] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Diabetes has been reported to increase CYP2E1 (cytochrome P450) and CYP2B1 expression at both the mRNA and protein levels in rat livers. This increase has been attributed to mRNA stabilization and can be reversed by daily insulin treatment. In a previous study, we showed that this hormone directly down-regulates CYP2E1 and 2B1 expression through a post-transcriptional mechanism in rat hepatoma cell lines. We then aimed to identify the molecular mechanisms involved in this regulation. We first identified a 16-mer sequence that we later showed to be the actual functional target of insulin on the rat CYP2E1 mRNA. Similar work was performed with CYP2B1. We first investigated the presence of mRNA-protein interactions. Using cytoplasmic proteins of Fao cells treated or not with insulin (0.1 microM) and the full-length CYP2B1 mRNA as a probe, a major CYP2B1 RNA-protein complex was observed with RNase T1 protection experiments. With the use of different CYP2B1 mRNA probes and by means of competition experiments with antisense oligonucleotides, a protein fixation site was located on a 16-nt sequence in the 5' part of the coding region. This sequence has a hairpin loop structure, shows 80% sequence identity with a structure previously identified on CYP2E1 and is also responsible for the post-transcriptional effects of insulin on this mRNA. Protein(s) bound to both CYP2B1 and CYP2E1 sequences are cytosolic and have an apparent molecular mass of 60 kDa. The protein(s) that bind(s) to both these sequences and the insulin transduction signal involved in this regulation remain(s) to identified.
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Affiliation(s)
- Nhu-Traï Truong
- INSERM UMR-S490, Laboratoire de Toxicologie Moléculaire, Faculté de Médecine, 45 Rue des Saints Pères 75270, Paris Cedex 06, France
| | - Arlette Moncion
- INSERM UMR-S490, Laboratoire de Toxicologie Moléculaire, Faculté de Médecine, 45 Rue des Saints Pères 75270, Paris Cedex 06, France
| | - Robert Barouki
- INSERM UMR-S490, Laboratoire de Toxicologie Moléculaire, Faculté de Médecine, 45 Rue des Saints Pères 75270, Paris Cedex 06, France
| | - Philippe Beaune
- INSERM UMR-S490, Laboratoire de Toxicologie Moléculaire, Faculté de Médecine, 45 Rue des Saints Pères 75270, Paris Cedex 06, France
| | - Isabelle de Waziers
- INSERM UMR-S490, Laboratoire de Toxicologie Moléculaire, Faculté de Médecine, 45 Rue des Saints Pères 75270, Paris Cedex 06, France
- To whom correspondence should be addressed (email )
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7
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Pavesi G, Mereghetti P, Zambelli F, Stefani M, Mauri G, Pesole G. MoD Tools: regulatory motif discovery in nucleotide sequences from co-regulated or homologous genes. Nucleic Acids Res 2006; 34:W566-70. [PMID: 16845071 PMCID: PMC1538899 DOI: 10.1093/nar/gkl285] [Citation(s) in RCA: 61] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
Understanding the complex mechanisms regulating gene expression at the transcriptional and post-transcriptional levels is one of the greatest challenges of the post-genomic era. The MoD (MOtif Discovery) Tools web server comprises a set of tools for the discovery of novel conserved sequence and structure motifs in nucleotide sequences, motifs that in turn are good candidates for regulatory activity. The server includes the following programs: Weeder, for the discovery of conserved transcription factor binding sites (TFBSs) in nucleotide sequences from co-regulated genes; WeederH, for the discovery of conserved TFBSs and distal regulatory modules in sequences from homologous genes; RNAProfile, for the discovery of conserved secondary structure motifs in unaligned RNA sequences whose secondary structure is not known. In this way, a given gene can be compared with other co-regulated genes or with its homologs, or its mRNA can be analyzed for conserved motifs regulating its post-transcriptional fate. The web server thus provides researchers with different strategies and methods to investigate the regulation of gene expression, at both the transcriptional and post-transcriptional levels. Available at and .
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Affiliation(s)
- Giulio Pavesi
- Dipartimento di Scienze Biomolecolari e Biotecnologie, University of MilanoMilano, Italy
| | - Paolo Mereghetti
- Dipartimento di Informatica, Sistemistica e Comunicazione, University of Milano-BicoccaMilano, Italy
| | - Federico Zambelli
- Dipartimento di Scienze Biomolecolari e Biotecnologie, University of MilanoMilano, Italy
| | - Marco Stefani
- Dipartimento di Informatica, Sistemistica e Comunicazione, University of Milano-BicoccaMilano, Italy
| | - Giancarlo Mauri
- Dipartimento di Informatica, Sistemistica e Comunicazione, University of Milano-BicoccaMilano, Italy
| | - Graziano Pesole
- Dipartimento di Scienze Biomolecolari e Biotecnologie, University of MilanoMilano, Italy
- Dipartimento di Biochimica e Biologia Molecolare, University of BariBari, Italy
- Istituto Tecnologie Biomediche—Consiglio Nazionale delle RicercheBari, Italy
- To whom correspondence should be addressed. Tel: +39 0250314915; Fax: +39 0805443317;
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Uzilov AV, Keegan JM, Mathews DH. Detection of non-coding RNAs on the basis of predicted secondary structure formation free energy change. BMC Bioinformatics 2006; 7:173. [PMID: 16566836 PMCID: PMC1570369 DOI: 10.1186/1471-2105-7-173] [Citation(s) in RCA: 130] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2005] [Accepted: 03/27/2006] [Indexed: 12/26/2022] Open
Abstract
BACKGROUND Non-coding RNAs (ncRNAs) have a multitude of roles in the cell, many of which remain to be discovered. However, it is difficult to detect novel ncRNAs in biochemical screens. To advance biological knowledge, computational methods that can accurately detect ncRNAs in sequenced genomes are therefore desirable. The increasing number of genomic sequences provides a rich dataset for computational comparative sequence analysis and detection of novel ncRNAs. RESULTS Here, Dynalign, a program for predicting secondary structures common to two RNA sequences on the basis of minimizing folding free energy change, is utilized as a computational ncRNA detection tool. The Dynalign-computed optimal total free energy change, which scores the structural alignment and the free energy change of folding into a common structure for two RNA sequences, is shown to be an effective measure for distinguishing ncRNA from randomized sequences. To make the classification as a ncRNA, the total free energy change of an input sequence pair can either be compared with the total free energy changes of a set of control sequence pairs, or be used in combination with sequence length and nucleotide frequencies as input to a classification support vector machine. The latter method is much faster, but slightly less sensitive at a given specificity. Additionally, the classification support vector machine method is shown to be sensitive and specific on genomic ncRNA screens of two different Escherichia coli and Salmonella typhi genome alignments, in which many ncRNAs are known. The Dynalign computational experiments are also compared with two other ncRNA detection programs, RNAz and QRNA. CONCLUSION The Dynalign-based support vector machine method is more sensitive for known ncRNAs in the test genomic screens than RNAz and QRNA. Additionally, both Dynalign-based methods are more sensitive than RNAz and QRNA at low sequence pair identities. Dynalign can be used as a comparable or more accurate tool than RNAz or QRNA in genomic screens, especially for low-identity regions. Dynalign provides a method for discovering ncRNAs in sequenced genomes that other methods may not identify. Significant improvements in Dynalign runtime have also been achieved.
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Affiliation(s)
- Andrew V Uzilov
- Department of Biochemistry & Biophysics, University of Rochester Medical Center, 601 Elmwood Avenue, Box 712, Rochester, New York 14642, USA
- Department of Biostatistics & Computational Biology, University of Rochester Medical Center, 601 Elmwood Avenue, Box 712, Rochester, New York 14642, USA
- Center for Pediatric Biomedical Research, University of Rochester Medical Center, 601 Elmwood Avenue, Box 712, Rochester, New York 14642, USA
| | - Joshua M Keegan
- Department of Biochemistry & Biophysics, University of Rochester Medical Center, 601 Elmwood Avenue, Box 712, Rochester, New York 14642, USA
- Department of Biostatistics & Computational Biology, University of Rochester Medical Center, 601 Elmwood Avenue, Box 712, Rochester, New York 14642, USA
- Center for Pediatric Biomedical Research, University of Rochester Medical Center, 601 Elmwood Avenue, Box 712, Rochester, New York 14642, USA
| | - David H Mathews
- Department of Biochemistry & Biophysics, University of Rochester Medical Center, 601 Elmwood Avenue, Box 712, Rochester, New York 14642, USA
- Department of Biostatistics & Computational Biology, University of Rochester Medical Center, 601 Elmwood Avenue, Box 712, Rochester, New York 14642, USA
- Center for Pediatric Biomedical Research, University of Rochester Medical Center, 601 Elmwood Avenue, Box 712, Rochester, New York 14642, USA
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Pavesi G, Mauri G, Stefani M, Pesole G. RNAProfile: an algorithm for finding conserved secondary structure motifs in unaligned RNA sequences. Nucleic Acids Res 2004; 32:3258-69. [PMID: 15199174 PMCID: PMC434454 DOI: 10.1093/nar/gkh650] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2004] [Revised: 04/05/2004] [Accepted: 05/21/2004] [Indexed: 11/13/2022] Open
Abstract
The recent interest sparked due to the discovery of a variety of functions for non-coding RNA molecules has highlighted the need for suitable tools for the analysis and the comparison of RNA sequences. Many trans-acting non-coding RNA genes and cis-acting RNA regulatory elements present motifs, conserved both in structure and sequence, that can be hardly detected by primary sequence analysis alone. We present an algorithm that takes as input a set of unaligned RNA sequences expected to share a common motif, and outputs the regions that are most conserved throughout the sequences, according to a similarity measure that takes into account both the sequence of the regions and the secondary structure they can form according to base-pairing and thermodynamic rules. Only a single parameter is needed as input, which denotes the number of distinct hairpins the motif has to contain. No further constraints on the size, number and position of the single elements comprising the motif are required. The algorithm can be split into two parts: first, it extracts from each input sequence a set of candidate regions whose predicted optimal secondary structure contains the number of hairpins given as input. Then, the regions selected are compared with each other to find the groups of most similar ones, formed by a region taken from each sequence. To avoid exhaustive enumeration of the search space and to reduce the execution time, a greedy heuristic is introduced for this task. We present different experiments, which show that the algorithm is capable of characterizing and discovering known regulatory motifs in mRNA like the iron responsive element (IRE) and selenocysteine insertion sequence (SECIS) stem-loop structures. We also show how it can be applied to corrupted datasets in which a motif does not appear in all the input sequences, as well as to the discovery of more complex motifs in the non-coding RNA.
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Affiliation(s)
- Giulio Pavesi
- Department of Computer Science and Communication-(D.I.Co.), University of Milan, Via Comelico 39, 20135 Milan, Italy
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10
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Alvares LE, Wuyts J, Van de Peer Y, Silva EP, Coutinho LL, Brison O, Ruiz IRG. The 18S rRNA from Odontophrynus americanus 2n and 4n (Amphibia, Anura) reveals unusual extra sequences in the variable region V2. Genome 2004; 47:421-8. [PMID: 15190359 DOI: 10.1139/g03-145] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The nucleotide sequence of the rDNA 18S region isolated from diploid and tetraploid species of the amphibian Odontophrynus americanus was determined and used to predict the secondary structure of the corresponding 18S rRNA molecules. Comparison of the primary and secondary structures for the 2n and 4n species confirmed that these species are very closely related. Only three nucleotide substitutions were observed, accounting for 99% identity between the 18S sequences, whereas several changes were detected by comparison with the Xenopus laevis 18S sequence (96% identity). Most changes were located in highly variable regions of the molecule. A noticeable feature of the Odontophrynus 18S rRNA was the presence of unusual extra sequences in the V2 region, between helices 9 and 11. These extra sequences do not fit the model for secondary structure predicted for vertebrate 18S rRNA.Key words: Odontophrynus americanus, Amphibia, polyploidy, 18S ribosomal DNA, molecular evolution.
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Zorn J, Gan HH, Shiffeldrim N, Schlick T. Structural motifs in ribosomal RNAs: implications for RNA design and genomics. Biopolymers 2004; 73:340-7. [PMID: 14755570 DOI: 10.1002/bip.10525] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
The various motifs of RNA molecules are closely related to their structural and functional properties. To better understand the nature and distributions of such structural motifs (i.e., paired and unpaired bases in stems, junctions, hairpin loops, bulges, and internal loops) and uncover characteristic features, we analyze the large 16S and 23S ribosomal RNAs of Escherichia coli. We find that the paired and unpaired bases in structural motifs have characteristic distribution shapes and ranges; for example, the frequency distribution of paired bases in stems declines linearly with the number of bases, whereas that for unpaired bases in junctions has a pronounced peak. Significantly, our survey reveals that the ratio of total (over the entire molecule) unpaired to paired bases (0.75) and the fraction of bases in stems (0.6), junctions (0.16), hairpin loops (0.12), and bulges/internal loops (0.12) are shared by 16S and 23S ribosomal RNAs, suggesting that natural RNAs may maintain certain proportions of bases in various motifs to ensure structural integrity. These findings may help in the design of novel RNAs and in the search (via constraints) for RNA-coding motifs in genomes, problems of intense current focus.
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MESH Headings
- Base Sequence
- Drug Design
- Escherichia coli/chemistry
- Escherichia coli/genetics
- Genomics
- Models, Molecular
- Molecular Sequence Data
- Nucleic Acid Conformation
- RNA, Bacterial/chemistry
- RNA, Bacterial/genetics
- RNA, Ribosomal/chemistry
- RNA, Ribosomal/genetics
- RNA, Ribosomal, 16S/chemistry
- RNA, Ribosomal, 16S/genetics
- RNA, Ribosomal, 23S/chemistry
- RNA, Ribosomal, 23S/genetics
- RNA, Transfer/chemistry
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Affiliation(s)
- Julie Zorn
- Department of Chemistry, New York University, 1021 Silver, 100 Washington Square East, New York, NY 10003, USA
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12
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Wein G, Rössler M, Klug R, Herget T. The 3'-UTR of the mRNA coding for the major protein kinase C substrate MARCKS contains a novel CU-rich element interacting with the mRNA stabilizing factors HuD and HuR. EUROPEAN JOURNAL OF BIOCHEMISTRY 2003; 270:350-65. [PMID: 12605686 DOI: 10.1046/j.1432-1033.2003.03396.x] [Citation(s) in RCA: 39] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The expression of the major protein kinase C substrate MARCKS (myristoylated alanine-rich C kinase substrate) is controlled by the stability of its mRNA. While the MARCKS mRNA is long living in quiescent fibroblasts (t1/2 = 14 h), its half-life time is drastically reduced (t1/2 = 2 h) in cells treated with phorbol esters to activate protein kinase C (PKC) or treated with growth factors. In a first step to study the underlying mechanism we identified both a cis-element on the MARCKS mRNA and the corresponding trans-acting factors. Fusing the complete 3'-UTR or specific regions of the 3'-UTR of the MARCKS gene to a luciferase reporter gene caused a drastic decrease in luciferase expression to as low as 5-10% of controls. This down-regulation was a result of destabilization of the chimeric transcript as shown by RNA run-off and Northern blot-assays. By RNase/EMSA and UV-cross-linking experiments, we identified a stretch of 52 nucleotides [(CUUU)11(U)8] in the 3'-UTR of the MARCKS mRNA specifically recognized by two RNA-binding proteins, HuD and HuR. These trans-acting factors are members of the ELAV gene family and bind the MARCKS CU-rich sequence with high affinity. Overexpression of HuD and HuR in murine fibroblasts caused a striking stabilization of the endogenous MARCKS mRNA even under conditions when the MARCKS mRNA is normally actively degraded, i.e. after treating cells with phorbol ester. These data imply, that the identified CU-rich cis-element of the MARCKS 3'-UTR is involved in conferring instability to mRNAs and that members of the ELAV gene family oppose this effect. Based on its structural and functional properties, the (CUUU)11(U)8 sequence described here can be grouped into class III of AU-rich elements.
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Affiliation(s)
- Georg Wein
- Institute of Physiological Chemistry and Pathobiochemistry, Johannes Gutenberg-University, Mainz, Germany
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13
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Moncion A, Truong NT, Garrone A, Beaune P, Barouki R, De Waziers I. Identification of a 16-Nucleotide Sequence That Mediates Post-transcriptional Regulation of Rat CYP2E1 by Insulin. J Biol Chem 2002; 277:45904-10. [PMID: 12270935 DOI: 10.1074/jbc.m207841200] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Insulin directly down-regulates the gene expression of the rat CYP2E1 by altering its mRNA stability (De Waziers, I., Garlatti, M., Bouguet, J., Beaune, P. H., and Barouki, R. (1995) Mol. Pharmacol. 47, 474-479). Because the regulation of CYP mRNA stability was poorly understood, the molecular mechanisms involved in this regulation in the rat hepatoma H4IIEC3 cell line were studied. By using RNase T1 protection methods, the formation of a major CYP2E1 RNA-protein complex was observed. By competition experiments, the binding site of this complex was located on a 16-nucleotide sequence in the 5'-proximal region of the CYP2E1-coding sequence. Insulin did not modify the binding pattern of proteins to this sequence. and transfections of expression vectors or antisense oligonucleotides were undertaken to demonstrate the actual functionality of the 16-mer sequence. The insertion of this sequence in a luciferase gene was sufficient to render the chimeric mRNA sensitive to insulin. Furthermore, transfection of H4IIEC3 cells with antisense oligonucleotide complementary to this sequence blocked the insulin effect on the CYP2E1 mRNA expression, i.e. its rapid degradation. All these results demonstrate that this 16-nucleotide sequence is implicated in the CYP2E1 post-transcriptional regulation by insulin.
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Affiliation(s)
- Arlette Moncion
- INSERM U490, Laboratoire de Toxicologie Moléculaire, Faculté de Médecine, 45 Rue des Saints Pères 75270, Paris Cedex 06, France
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14
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Suzuma S, Asari S, Bunai K, Yoshino K, Ando Y, Kakeshita H, Fujita M, Nakamura K, Yamane K. Identification and characterization of novel small RNAs in the aspS-yrvM intergenic region of the Bacillus subtilis genome. MICROBIOLOGY (READING, ENGLAND) 2002; 148:2591-2598. [PMID: 12177353 DOI: 10.1099/00221287-148-8-2591] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
A novel RNA species was isolated from Bacillus subtilis, and its sequence was determined and mapped to its genetic position. This RNA was termed BS190 RNA from the length of its mature form (190 nt), and the gene encoding it is located within the aspS-yrvM intergenic region of the B. subtilis genome. Northern blotting revealed that the novel RNA species is transcribed in vegetative cells as a larger precursor (BS201 RNA, 201 nt). After transcription, the 5' end of the precursor is processed to generate the mature form, BS190 RNA. A computer-aided prediction of the secondary structure of BS190 RNA showed that it can be folded into a single hairpin structure with some bulge structures. The authors found that the growth rate of a DeltaBS190 mutant strain of B. subtilis was reduced when compared to the wild-type. A phylogenetic comparison of the sequence of the BS190 RNA gene with sequences from the databases suggests that RNA related to BS190 RNA appears to be encoded in the genomes of Bacillus halodurans and Listeria monocytogenes.
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MESH Headings
- Bacillus subtilis/genetics
- Bacillus subtilis/metabolism
- Base Sequence
- Chromosome Mapping
- DNA, Bacterial
- DNA, Intergenic/genetics
- Genome, Bacterial
- Molecular Sequence Data
- Nucleic Acid Conformation
- RNA Processing, Post-Transcriptional
- RNA, Bacterial/chemistry
- RNA, Bacterial/genetics
- RNA, Bacterial/metabolism
- RNA, Untranslated/chemistry
- RNA, Untranslated/genetics
- RNA, Untranslated/metabolism
- Sequence Analysis, DNA
- Transcription, Genetic
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Affiliation(s)
- Satoru Suzuma
- Institute of Biological Sciences, University of Tsukuba, Tsukuba-shi, Ibaraki 305-8572, Japan1
| | - Sayaka Asari
- Institute of Biological Sciences, University of Tsukuba, Tsukuba-shi, Ibaraki 305-8572, Japan1
| | - Keigo Bunai
- Institute of Biological Sciences, University of Tsukuba, Tsukuba-shi, Ibaraki 305-8572, Japan1
| | - Keiko Yoshino
- Institute of Biological Sciences, University of Tsukuba, Tsukuba-shi, Ibaraki 305-8572, Japan1
| | - Yoshinari Ando
- Institute of Biological Sciences, University of Tsukuba, Tsukuba-shi, Ibaraki 305-8572, Japan1
| | - Hiroshi Kakeshita
- Institute of Biological Sciences, University of Tsukuba, Tsukuba-shi, Ibaraki 305-8572, Japan1
| | - Masaya Fujita
- Department of Molecular and Cellular Biology, The Biological Laboratories, Harvard University, 16 Divinity Avenue, Cambridge, MA 01238, USA2
| | - Kouji Nakamura
- Institute of Biological Sciences, University of Tsukuba, Tsukuba-shi, Ibaraki 305-8572, Japan1
| | - Kunio Yamane
- Institute of Biological Sciences, University of Tsukuba, Tsukuba-shi, Ibaraki 305-8572, Japan1
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15
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Eddy SR. A memory-efficient dynamic programming algorithm for optimal alignment of a sequence to an RNA secondary structure. BMC Bioinformatics 2002; 3:18. [PMID: 12095421 PMCID: PMC119854 DOI: 10.1186/1471-2105-3-18] [Citation(s) in RCA: 145] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2002] [Accepted: 07/02/2002] [Indexed: 11/22/2022] Open
Abstract
BACKGROUND Covariance models (CMs) are probabilistic models of RNA secondary structure, analogous to profile hidden Markov models of linear sequence. The dynamic programming algorithm for aligning a CM to an RNA sequence of length N is O(N3) in memory. This is only practical for small RNAs. RESULTS I describe a divide and conquer variant of the alignment algorithm that is analogous to memory-efficient Myers/Miller dynamic programming algorithms for linear sequence alignment. The new algorithm has an O(N2 log N) memory complexity, at the expense of a small constant factor in time. CONCLUSIONS Optimal ribosomal RNA structural alignments that previously required up to 150 GB of memory now require less than 270 MB.
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Affiliation(s)
- Sean R Eddy
- Howard Hughes Medical Institute & Department of Genetics, Washington University School of Medicine, Saint Louis, Missouri 63110 USA.
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16
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Abstract
The number of known noncoding RNA genes is expanding rapidly. Computational analysis of genome sequences, which has been revolutionary for protein gene analysis, should also be able to address questions of the number and diversity of noncoding RNA genes. However, noncoding RNAs present computational genomics with a new set of challenges.
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Affiliation(s)
- Sean R Eddy
- Howard Hughes Medical Institute, Department of Genetics, Washington University School of Medicine, St. Louis, MO 63110, USA.
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17
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Ando Y, Asari S, Suzuma S, Yamane K, Nakamura K. Expression of a small RNA, BS203 RNA, from the yocI-yocJ intergenic region of Bacillus subtilis genome. FEMS Microbiol Lett 2002; 207:29-33. [PMID: 11886746 DOI: 10.1111/j.1574-6968.2002.tb11023.x] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
Abstract
We isolated and characterized a novel small RNA from Bacillus subtilis. We termed this molecule BS203 RNA from the length of its mature form (203 nt) and located the corresponding gene at the yocI-yocJ intergenic region on the B. subtilis genome. Northern blotting revealed that it is transcribed in vegetative growing cells and that the amount of BS203 RNA decreased in the middle of the vegetative phase. A computer-aided prediction of the BS203 RNA secondary structure revealed three characteristic stem-loop structures. Despite active expression during the vegetative phase, growth of the knockout mutant was not affected by depletion of BS203 RNA. A phylogenetic comparison of the sequence of the BS203 RNA with other Bacillus species including B. cereus and B. halodurans C-125, or Clostridium perfringens suggests that the sequence is unique to Bacillus subtilis.
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MESH Headings
- Bacillus subtilis/genetics
- Bacillus subtilis/growth & development
- Bacillus subtilis/metabolism
- Base Sequence
- DNA, Intergenic/genetics
- Gene Deletion
- Gene Expression Regulation
- Genes, Bacterial
- Molecular Sequence Data
- Nucleic Acid Conformation
- RNA, Bacterial/chemistry
- RNA, Bacterial/genetics
- RNA, Bacterial/metabolism
- RNA, Untranslated/chemistry
- RNA, Untranslated/genetics
- RNA, Untranslated/metabolism
- Sequence Analysis, DNA
- Transcription, Genetic
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Affiliation(s)
- Yoshinari Ando
- Institute of Biological Sciences, University of Tsukuba, Ibaraki 305-8572, Tsukuba-shi, Japan
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18
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Meyer C, Giegerich R. Matching and Significance Evaluation of Combined Sequence-Structure Motifs in RNA. Z PHYS CHEM 2002. [DOI: 10.1524/zpch.2002.216.2.193] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
The discipline of Algebraic Dynamic Programming is a powerful method to design and implement versatile pattern matching algorithms on sequences; here we consider mixed sequence and secondary structure motifs in RNA. A recurring challenge when designing new pattern matchers is to provide a statistical analysis of pattern significance. We demonstrate that by the use of so-called canonical pattern descriptions, the expected number of hits on a sequence of length
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19
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Abstract
Like other organisms, insects must balance two properties of ionic iron, that of an essential nutrient and a potent toxin. Iron must be acquired to provide catalysis for oxidative metabolism, but it must be controlled to avoid destructive oxidative reactions. Insects have evolved distinctive forms of the serum iron transport protein, transferrin, and the storage protein, ferritin. These proteins may serve different functions in insects than they do in other organisms. A form of translational control of protein synthesis by iron in insects is similar to that of vertebrates. The Drosophila melanogaster genome contains many genes that may encode other proteins involved in iron metabolism.
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Affiliation(s)
- Helen Nichol
- Department of Nutritional Science, University of Arizona, Shantz 309, P.O. Box 210038, Tucson, Arizona 85721-0038, USA.
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20
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Witwer C, Rauscher S, Hofacker IL, Stadler PF. Conserved RNA secondary structures in Picornaviridae genomes. Nucleic Acids Res 2001; 29:5079-89. [PMID: 11812840 PMCID: PMC97546 DOI: 10.1093/nar/29.24.5079] [Citation(s) in RCA: 78] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
The family Picornaviridae contains important pathogens including, for example, hepatitis A virus and foot-and-mouth disease virus. The genome of these viruses is a single messenger-active (+)-RNA of 7200-8500 nt. Besides coding for the viral proteins, it also contains functionally important RNA secondary structures, among them an internal ribosomal entry site (IRES) region towards the 5'-end. This contribution provides a comprehensive computational survey of the complete genomic RNAs and a detailed comparative analysis of the conserved structural elements in seven of the currently nine genera in the family PICORNAVIRIDAE: Compared with previous studies we find: (i) that only smaller sections of the IRES region than previously reported are conserved at single base-pair resolution and (ii) that there is a number of significant structural elements in the coding region. Furthermore, we identify potential cis-acting replication elements in four genera where this feature has not been reported so far.
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Affiliation(s)
- C Witwer
- Institut für Theoretische Chemie und Molekulare Strukturbiologie, Universität Wien, Währingerstrasse 17, A-1090 Wien, Austria
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21
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Gorodkin J, Stricklin SL, Stormo GD. Discovering common stem-loop motifs in unaligned RNA sequences. Nucleic Acids Res 2001; 29:2135-44. [PMID: 11353083 PMCID: PMC55461 DOI: 10.1093/nar/29.10.2135] [Citation(s) in RCA: 97] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2001] [Revised: 03/14/2001] [Accepted: 03/27/2001] [Indexed: 11/13/2022] Open
Abstract
Post-transcriptional regulation of gene expression is often accomplished by proteins binding to specific sequence motifs in mRNA molecules, to affect their translation or stability. The motifs are often composed of a combination of sequence and structural constraints such that the overall structure is preserved even though much of the primary sequence is variable. While several methods exist to discover transcriptional regulatory sites in the DNA sequences of coregulated genes, the RNA motif discovery problem is much more difficult because of covariation in the positions. We describe the combined use of two approaches for RNA structure prediction, FOLDALIGN and COVE, that together can discover and model stem-loop RNA motifs in unaligned sequences, such as UTRs from post-transcriptionally coregulated genes. We evaluate the method on two datasets, one a section of rRNA genes with randomly truncated ends so that a global alignment is not possible, and the other a hyper-variable collection of IRE-like elements that were inserted into randomized UTR sequences. In both cases the combined method identified the motifs correctly, and in the rRNA example we show that it is capable of determining the structure, which includes bulge and internal loops as well as a variable length hairpin loop. Those automated results are quantitatively evaluated and found to agree closely with structures contained in curated databases, with correlation coefficients up to 0.9. A basic server, Stem-Loop Align SearcH (SLASH), which will perform stem-loop searches in unaligned RNA sequences, is available at http://www.bioinf.au.dk/slash/.
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Affiliation(s)
- J Gorodkin
- Department of Genetics and Ecology, The Institute of Biological Sciences, University of Aarhus, Building 540, Ny Munkegade, DK-8000 Aarhus C, Denmark
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22
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Abstract
Iron is vital for almost all living organisms by participating in a wide variety of metabolic processes, including oxygen transport, DNA synthesis, and electron transport. However, iron concentrations in body tissues must be tightly regulated because excessive iron leads to tissue damage, as a result of formation of free radicals. Disorders of iron metabolism are among the most common diseases of humans and encompass a broad spectrum of diseases with diverse clinical manifestations, ranging from anemia to iron overload and, possibly, to neurodegenerative diseases. The molecular understanding of iron regulation in the body is critical in identifying the underlying causes for each disease and in providing proper diagnosis and treatments. Recent advances in genetics, molecular biology and biochemistry of iron metabolism have assisted in elucidating the molecular mechanisms of iron homeostasis. The coordinate control of iron uptake and storage is tightly regulated by the feedback system of iron responsive element-containing gene products and iron regulatory proteins that modulate the expression levels of the genes involved in iron metabolism. Recent identification and characterization of the hemochromatosis protein HFE, the iron importer Nramp2, the iron exporter ferroportin1, and the second transferrin-binding and -transport protein transferrin receptor 2, have demonstrated their important roles in maintaining body's iron homeostasis. Functional studies of these gene products have expanded our knowledge at the molecular level about the pathways of iron metabolism and have provided valuable insight into the defects of iron metabolism disorders. In addition, a variety of animal models have implemented the identification of many genetic defects that lead to abnormal iron homeostasis and have provided crucial clinical information about the pathophysiology of iron disorders. In this review, we discuss the latest progress in studies of iron metabolism and our current understanding of the molecular mechanisms of iron absorption, transport, utilization, and storage. Finally, we will discuss the clinical presentations of iron metabolism disorders, including secondary iron disorders that are either associated with or the result of abnormal iron accumulation.
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Affiliation(s)
- P T Lieu
- The R.W. Johnson Pharmaceutical Research Institute, 3210 Merryfield Row, San Diego, CA 92121, USA
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23
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Lescure A, Gautheret D, Carbon P, Krol A. Novel selenoproteins identified in silico and in vivo by using a conserved RNA structural motif. J Biol Chem 1999; 274:38147-54. [PMID: 10608886 DOI: 10.1074/jbc.274.53.38147] [Citation(s) in RCA: 213] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Selenocysteine is incorporated into selenoproteins by an in-frame UGA codon whose readthrough requires the selenocysteine insertion sequence (SECIS), a conserved hairpin in the 3'-untranslated region of eukaryotic selenoprotein mRNAs. To identify new selenoproteins, we developed a strategy that obviates the need for prior amino acid sequence information. A computational screen was used to scan nucleotide sequence data bases for sequences presenting a potential SECIS secondary structure. The computer-selected hairpins were then assayed in vivo for their functional capacities, and the cDNAs corresponding to the SECIS winners were identified. Four of them encoded novel selenoproteins as confirmed by in vivo experiments. Among these, SelZf1 and SelZf2 share a common domain with mitochondrial thioredoxin reductase-2. The three proteins, however, possess distinct N-terminal domains. We found that another protein, SelX, displays sequence similarity to a protein involved in bacterial pilus formation. For the first time, four novel selenoproteins were discovered based on a computational screen for the RNA hairpin directing selenocysteine incorporation.
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Affiliation(s)
- A Lescure
- Unité Propre de Recherche CNRS 9002, Structure des Macromolécules Biologiques et Mécanismes de Reconnaissance, Institut de Biologie Moleculaire et Cellulaire, 15, Rue René Descartes, 67084 Strasbourg Cedex, France
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24
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Abstract
Some genes produce RNAs that are functional instead of encoding proteins. Noncoding RNA genes are surprisingly numerous. Recently, active research areas include small nucleolar RNAs, antisense riboregulator RNAs, and RNAs involved in X-dosage compensation. Genome sequences and new algorithms have begun to make systematic computational screens for noncoding RNA genes possible.
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Affiliation(s)
- S R Eddy
- Department of Genetics, Washington University School of Medicine, St Louis 63110, USA.
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25
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Bourdeau V, Ferbeyre G, Pageau M, Paquin B, Cedergren R. The distribution of RNA motifs in natural sequences. Nucleic Acids Res 1999; 27:4457-67. [PMID: 10536156 PMCID: PMC148730 DOI: 10.1093/nar/27.22.4457] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Functional analysis of genome sequences has largely ignored RNA genes and their structures. We introduce here the notion of 'ribonomics' to describe the search for the distribution of and eventually the determination of the physiological roles of these RNA structures found in the sequence databases. The utility of this approach is illustrated here by the identification in the GenBank database of RNA motifs having known binding or chemical activity. The frequency of these motifs indicates that most have originated from evolutionary drift and are selectively neutral. On the other hand, their distribution among species and their location within genes suggest that the destiny of these motifs may be more elaborate. For example, the hammerhead motif has a skewed organismal presence, is phylogenetically stable and recent work on a schistosome version confirms its in vivo biological activity. The under-representation of the valine-binding motif and the Rev-binding element in GenBank hints at a detrimental effect on cell growth or viability. Data on the presence and the location of these motifs may provide critical guidance in the design of experiments directed towards the understanding and the manipulation of RNA complexes and activities in vivo.
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Affiliation(s)
- V Bourdeau
- Département de Biochimie, Université de Montréal, C.P. 6128, Succursale Centre-Ville, Montréal, QC H3C 3J7, Canada
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26
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Mikulits W, Schranzhofer M, Beug H, Müllner EW. Post-transcriptional control via iron-responsive elements: the impact of aberrations in hereditary disease. Mutat Res 1999; 437:219-30. [PMID: 10592329 DOI: 10.1016/s1383-5742(99)00085-x] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
Tight regulation of iron metabolism is crucial to avoid formation of deleterious radicals and is mainly executed at the post-transcriptional level. The regulatory loops are exerted by trans-acting iron regulatory proteins (IRPs) and cis-acting stem-loop motifs, termed iron-responsive elements (IREs), located in the untranslated regions (UTRs) of target mRNAs. Iron scarcity induces binding of IRPs to a single IRE in the 5'-UTR of ferritin, eALAS, aconitase and SDHb mRNAs, which specifically suppresses translation initiation. Simultaneous interaction of IRPs with multiple IREs in the 3'-UTR of transferrin receptor (TfR) mRNA selectively causes its stabilization. The pattern is reverted under iron overload: IRP-mRNA binding affinity is reduced, which results in efficient protein synthesis of target transcripts harboring IREs in the 5'-UTR and rapid degradation of TfR mRNA. Although multiple evidences support this model, several studies reported massive alterations in the regulation of iron homeostasis under specific physiological conditions, raising the possibility for additional regulatory events. Intensive analysis of the palindromic IRE consensus sequence revealed the critical elements for the formation of a functional structure and demonstrated the consequences of IRE mutations in IRP binding. Recent investigations indicated the involvement of naturally occurring IRE mutations of the ferritin L subunit in the hyperferritinemia-cataract syndrome, a hereditary disorder. This review summarizes the apparent links between iron-dependent post-transcriptional control and its abnormalities, governed by the properties of a single mRNA stem-loop structure.
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Affiliation(s)
- W Mikulits
- Institute of Cancer Research, University of Vienna, Borschkegasse 8a, A-1090, Vienna, Austria
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27
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Hofacker IL, Stadler PF. Automatic detection of conserved base pairing patterns in RNA virus genomes. COMPUTERS & CHEMISTRY 1999; 23:401-14. [PMID: 10404627 DOI: 10.1016/s0097-8485(99)00013-3] [Citation(s) in RCA: 44] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
Almost all RNA molecules--and consequently also almost all subsequences of a large RNA molecule-form secondary structures. The presence of secondary structure in itself therefore does not indicate any functional significance. In fact, we cannot expect a conserved secondary structure for all parts of a viral genome or a mRNA, even if there is a significant level of sequence conservation. We present a novel method for detecting conserved RNA secondary structures in a family of related RNA sequences. The method is based on combining the prediction of base pair probability matrices and comparative sequence analysis. It can be applied to small sets of long sequences and does not require a prior knowledge of conserved sequence or structure motifs. As such it can be used to scan large amounts of sequence data for regions that warrant further experimental investigation. Applications to complete genomic RNAs of some viruses show that in all cases the known secondary structure features are identified. In addition, we predict a substantial number of conserved structural elements which have not been described so far.
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Affiliation(s)
- I L Hofacker
- Institut für Theoretische Chemie, Universität Wien, Austria
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28
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Beyer K, Dandekar T, Keller W. RNA ligands selected by cleavage stimulation factor contain distinct sequence motifs that function as downstream elements in 3'-end processing of pre-mRNA. J Biol Chem 1997; 272:26769-79. [PMID: 9334264 DOI: 10.1074/jbc.272.42.26769] [Citation(s) in RCA: 79] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
Critical events in 3'-end processing of pre-mRNA are the recognition of the AAUAAA polyadenylation signal by cleavage and polyadenylation specificity factor (CPSF) and the binding of cleavage stimulation factor (CstF) via its 64-kDa subunit to the downstream element. The stability of this CPSF.CstF.RNA complex is thought to determine the efficiency of 3'-end processing. Since downstream elements reveal high sequence variability, in vitro selection experiments with highly purified CstF were performed to investigate the sequence requirements for CstF-RNA interaction. CstF was purified from calf thymus and from HeLa cells. Surprisingly, calf thymus CstF contained an additional, novel form of the 64-kDa subunit with a molecular mass of 70 kDa. RNA ligands selected by HeLa and calf thymus CstF contained three highly conserved sequence elements as follows: element 1 (AUGCGUUCCUCGUCC) and two closely related elements, element 2a (YGUGUYN0-4UUYAYUGYGU) and element 2b (UUGYUN0-4AUUUACU(U/G)N0-2YCU). All selected sequences tested functioned as downstream elements in 3'-end processing in vitro. A computer survey of the EMBL data library revealed significant homologies to all selected elements in naturally occurring 3'-untranslated regions. The majority of element 2a homologies was found downstream of coding sequences. Therefore, we postulate that this element represents a novel consensus sequence for downstream elements in 3'-end processing of pre-mRNA.
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Affiliation(s)
- K Beyer
- Department of Cell Biology, Biozentrum of the University of Basel, Klingelbergstrasse 70, CH-4056 Basel, Switzerland
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29
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Chetouani F, Monestié P, Thébault P, Gaspin C, Michot B. ESSA: an integrated and interactive computer tool for analysing RNA secondary structure. Nucleic Acids Res 1997; 25:3514-22. [PMID: 9254713 PMCID: PMC146922 DOI: 10.1093/nar/25.17.3514] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
With ESSA, we propose an approach of RNA secondary structure analysis based on extensive viewing within a friendly graphical interface. This computer program is organized around the display of folding models produced by two complementary methods suitable to draw long RNA molecules. Any feature of interest can be managed directly on the display and highlighted by a rich combination of colours and symbols with emphasis given to structural probe accessibilities. ESSA also includes a word searching procedure allowing easy visual identification of structural features even complex and degenerated. Analysis functions make it possible to calculate the thermodynamic stability of any part of a folding using several models and compare homologous aligned RNA both in primary and secondary structure. The predictive capacities of ESSA which brings together the experimental, thermodynamic and comparative methods, are increased by coupling it with a program dedicated to RNA folding prediction based on constraints management and propagation. The potentialities of ESSA are illustrated by the identification of a possible tertiary motif in the LSU rRNA and the visualization of a pseudoknot in S15 mRNA.
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Affiliation(s)
- F Chetouani
- Laboratoire de Biologie Moléculaire Eucaryote du C.N.R.S., Université Paul Sabatier, 118 route de Narbonne, 31062 Toulouse Cedex, France
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30
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Abstract
Bioinformatics is now an essential tool in many aspects of human molecular genetics research. Methods for the prediction of gene structure are essential components in genomic sequencing projects and provide the key to deriving protein sequence and locating intron/exon junctions. Sequence comparison and database searching are the pre-eminent approaches for predicting the likely biochemical function of new genes, although sequence profiles derived from families of aligned sequences have advantages in the detection of remote sequence relationships. The use of sequence database analysis for large-scale comparative analysis of genome sequence data from model organisms is emerging as the most important recent development in the application of bioinformatics methods for characterizing candidate disease genes.
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Affiliation(s)
- C J Rawlings
- SmithKline Beecham Pharmaceuticals, Department of Bioinformatics, Harlow, Essex, UK.
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31
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Lowe TM, Eddy SR. tRNAscan-SE: a program for improved detection of transfer RNA genes in genomic sequence. Nucleic Acids Res 1997. [PMID: 9023104 DOI: 10.1093/nar/25.5.0955] [Citation(s) in RCA: 3186] [Impact Index Per Article: 118.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
We describe a program, tRNAscan-SE, which identifies 99-100% of transfer RNA genes in DNA sequence while giving less than one false positive per 15 gigabases. Two previously described tRNA detection programs are used as fast, first-pass prefilters to identify candidate tRNAs, which are then analyzed by a highly selective tRNA covariance model. This work represents a practical application of RNA covariance models, which are general, probabilistic secondary structure profiles based on stochastic context-free grammars. tRNAscan-SE searches at approximately 30 000 bp/s. Additional extensions to tRNAscan-SE detect unusual tRNA homologues such as selenocysteine tRNAs, tRNA-derived repetitive elements and tRNA pseudogenes.
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Affiliation(s)
- T M Lowe
- Department of Genetics, Washington University School of Medicine, 660 South Euclid, Box 8232, St Louis, MO 63110, USA
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32
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Lowe TM, Eddy SR. tRNAscan-SE: a program for improved detection of transfer RNA genes in genomic sequence. Nucleic Acids Res 1997; 25:955-64. [PMID: 9023104 PMCID: PMC146525 DOI: 10.1093/nar/25.5.955] [Citation(s) in RCA: 7458] [Impact Index Per Article: 276.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
We describe a program, tRNAscan-SE, which identifies 99-100% of transfer RNA genes in DNA sequence while giving less than one false positive per 15 gigabases. Two previously described tRNA detection programs are used as fast, first-pass prefilters to identify candidate tRNAs, which are then analyzed by a highly selective tRNA covariance model. This work represents a practical application of RNA covariance models, which are general, probabilistic secondary structure profiles based on stochastic context-free grammars. tRNAscan-SE searches at approximately 30 000 bp/s. Additional extensions to tRNAscan-SE detect unusual tRNA homologues such as selenocysteine tRNAs, tRNA-derived repetitive elements and tRNA pseudogenes.
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Affiliation(s)
- T M Lowe
- Department of Genetics, Washington University School of Medicine, 660 South Euclid, Box 8232, St Louis, MO 63110, USA
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33
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Hentze MW, Kühn LC. Molecular control of vertebrate iron metabolism: mRNA-based regulatory circuits operated by iron, nitric oxide, and oxidative stress. Proc Natl Acad Sci U S A 1996; 93:8175-82. [PMID: 8710843 PMCID: PMC38642 DOI: 10.1073/pnas.93.16.8175] [Citation(s) in RCA: 973] [Impact Index Per Article: 34.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023] Open
Abstract
As an essential nutrient and a potential toxin, iron poses an exquisite regulatory problem in biology and medicine. At the cellular level, the basic molecular framework for the regulation of iron uptake, storage, and utilization has been defined. Two cytoplasmic RNA-binding proteins, iron-regulatory protein-1 (IRP-1) and IRP-2, respond to changes in cellular iron availability and coordinate the expression of mRNAs that harbor IRP-binding sites, iron-responsive elements (IREs). Nitric oxide (NO) and oxidative stress in the form of H2O2 also signal to IRPs and thereby influence cellular iron metabolism. The recent discovery of two IRE-regulated mRNAs encoding enzymes of the mitochondrial citric acid cycle may represent the beginnings of elucidating regulatory coupling between iron and energy metabolism. In addition to providing insights into the regulation of iron metabolism and its connections with other cellular pathways, the IRE/IRP system has emerged as a prime example for the understanding of translational regulation and mRNA stability control. Finally, IRP-1 has highlighted an unexpected role for iron sulfur clusters as post-translational regulatory switches.
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Affiliation(s)
- M W Hentze
- Gene Expression Programme, European Molecular Biology Laboratory, Heidelberg, Germany
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34
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Milland J, Christiansen D, Thorley BR, McKenzie IF, Loveland BE. Translation is enhanced after silent nucleotide substitutions in A+T- rich sequences of the coding region of CD46 cDNA. EUROPEAN JOURNAL OF BIOCHEMISTRY 1996; 238:221-30. [PMID: 8665941 DOI: 10.1111/j.1432-1033.1996.0221q.x] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
Specific sequences in the coding region of CD46 (membrane cofactor protein) transcripts have been shown to have a marked effect on translation. Two A+T-rich regions of CD46 cDNA were altered by mutation without changing the CD46 amino acid sequence (silent nucleotide substitution). In one region, the A+T content was reduced from 78% to 55% and in the other a putative polyadenylation addition sequence was disrupted. In each example, mutated sequences transfected into COS-7 cells produced significantly more soluble or cell surface protein (up to a 20-fold increase) than wild-type sequences. The amount of cellular plasmid DNA and CD46 mRNA was not increased, suggesting that the effect was not due to increased transfection efficiency, or transcript synthesis or stability. Biosynthetically labelled transfected cells showed an increase in translation rate but cell-free in vitro translation studies demonstrated that wild-type and mutated transcripts were translated with similar efficiency. The data show that translation of CD46 is affected by specific mRNA coding sequences, 400-540 bases from the initiation codon, and suggest that these sequences require the structural integrity of the cell to exert their effect.
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Affiliation(s)
- J Milland
- Austin Research Institute, Heidelberg, Australia
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35
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Gray NK, Pantopoulos K, Dandekar T, Ackrell BA, Hentze MW. Translational regulation of mammalian and Drosophila citric acid cycle enzymes via iron-responsive elements. Proc Natl Acad Sci U S A 1996; 93:4925-30. [PMID: 8643505 PMCID: PMC39381 DOI: 10.1073/pnas.93.10.4925] [Citation(s) in RCA: 131] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023] Open
Abstract
The posttranscriptional control of iron uptake, storage, and utilization by iron-responsive elements (IREs) and iron regulatory proteins (IRPs) provides a molecular framework for the regulation of iron homeostasis in many animals. We have identified and characterized IREs in the mRNAs for two different mitochondrial citric acid cycle enzymes. Drosophila melanogaster IRP binds to an IRE in the 5' untranslated region of the mRNA encoding the iron-sulfur protein (Ip) subunit of succinate dehydrogenase (SDH). This interaction is developmentally regulated during Drosophila embryogenesis. In a cell-free translation system, recombinant IRP-1 imposes highly specific translational repression on a reporter mRNA bearing the SDH IRE, and the translation of SDH-Ip mRNA is iron regulated in D. melanogaster Schneider cells. In mammals, an IRE was identified in the 5' untranslated regions of mitochondrial aconitase mRNAs from two species. Recombinant IRP-1 represses aconitase synthesis with similar efficiency as ferritin IRE-controlled translation. The interaction between mammalian IRPs and the aconitase IRE is regulated by iron, nitric oxide, and oxidative stress (H2O2), indicating that these three signals can control the expression of mitochondrial aconitase mRNA. Our results identify a regulatory link between energy and iron metabolism in vertebrates and invertebrates, and suggest biological functions for the IRE/IRP regulatory system in addition to the maintenance of iron homeostasis.
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Affiliation(s)
- N K Gray
- Gene Expression Programme, European Molecular Biology Laboratory, Heidelberg, Germany
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36
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Stumpf G, Goppelt A, Domdey H. Pre-mRNA topology is important for 3'-end formation in Saccharomyces cerevisiae and mammals. Mol Cell Biol 1996; 16:2204-13. [PMID: 8628287 PMCID: PMC231208 DOI: 10.1128/mcb.16.5.2204] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023] Open
Abstract
Various signal motifs that are required for efficient pre-mRNA 3'-end formation in the yeast Saccharomyces cerevisiae have been reported. None of these known signal sequences appears to be of the same general importance as is the mammalian AAUAAA motif. To establish the importance of yeast pre-mRNA termini in 3'-end formation, the ends of a pre-mRNA transcript synthesized in vitro were ligated before incubation in a yeast whole-cell extract. Such covalently closed circular RNAs were not cleaved at their poly(A) sites. Interestingly, pseudocircular RNAs with complementary 3'- and 5'-terminal sequences allowing the formation of panhandle structures were also resistant to cleavage. However, 3'-end processing was impeded neither by terminal hairpins at either or at both ends nor by RNA oligonucleotides complementary to either or both ends of a linear pre-mRNA. Intriguingly mammalian pseudocircular pre-mRNAs also were not cleaved at their poly(A) sites when incubated in a HeLa cell nuclear extract. These results provide evidence for the general importance of RNA topology in the formation of an active 3'-end processing complex in S. cerevisiae and higher eukaryotes. The possibility of a torus-shaped factor involved in 3'-end formation is discussed.
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Affiliation(s)
- G Stumpf
- Institut für Biochemie, Genzentrum der Ludwig-Maximilians-Universität, München, Germany
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Billoud B, Kontic M, Viari A. Palingol: a declarative programming language to describe nucleic acids' secondary structures and to scan sequence database. Nucleic Acids Res 1996; 24:1395-403. [PMID: 8628670 PMCID: PMC145829 DOI: 10.1093/nar/24.8.1395] [Citation(s) in RCA: 54] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023] Open
Abstract
At the DNA/RNA level, biological signals are defined by a combination of spatial structures and sequence motifs. Until now, few attempts had been made in writing general purpose search programs that take into account both sequence and structure criteria. Indeed, the most successful structure scanning programs are usually dedicated to particular structures and are written using general purpose programming languages through a complex and time consuming process where the biological problem of defining the structure and the computer engineering problem of looking for it are intimately intertwined. In this paper, we describe a general representation of structures, suitable for database scanning, together with a programming language, Palingol, designed to manipulate it. Palingol has specific data types, corresponding to structural elements-basically helices-that can be arranged in any way to form a complex structure. As a consequence of the declarative approach used in Palingol, the user should only focus on 'what to search for' while the language engine takes care of 'how to look for it'. Therefore, it becomes simpler to write a scanning program and the structural constraints that define the required structure are more clearly identified.
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Affiliation(s)
- B Billoud
- Atelier de Bio-informatique URA CNRS 448, Institut Curie, Paris, France
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Huang TS, Law JH, Söderhäll K. Purification and cDNA cloning of ferritin from the hepatopancreas of the freshwater crayfish Pacifastacus leniusculus. EUROPEAN JOURNAL OF BIOCHEMISTRY 1996; 236:450-6. [PMID: 8612615 DOI: 10.1111/j.1432-1033.1996.00450.x] [Citation(s) in RCA: 57] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Ferritin was purified from the hepatopancreas of the freshwater crayfish Pacifastacus leniusculus after injection of iron. It has the same size as horse spleen ferritin (440 kDa) and migrates as two bands, 19 kDa and 20 kDa, respectively, in SDS/PAGE under reducing conditions. Crayfish ferritin (20 kDa) was cloned from a hepatopancreas cDNA library. The deduced amino acid sequence of the crayfish ferritin shows a closer relationship to vertebrate ferritin heavy chains than to insect ferritin and contains the conserved H-specific residues for the ferroxidase centre found in vertebrate ferritin heavy chain. An IRE(iron-responsive element)-like sequence with a predicted stem-loop structure was present in the 5' untranslated region of the crayfish ferritin mRNA. Crayfish ferritin does not share the atypical properties of insect ferritins, such as high molecular mass of intact protein, abundance in hemolymph, and export into vacuoles. We suggest that there are two different types of ferritins distributed in different species: insect-type or secretory ferritins which are predominant in the snail oocyte and insects, and vertebrate (crustacean)-type or cytosolic ferritins which are predominant in vertebrates and crustacea.
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Affiliation(s)
- T S Huang
- Department of Physiological Botany, University of Uppsala, Sweden
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Dandekar T, Koch G. DNA and mRNA sequence of the immune protective DNA ligase I gene match the rev response element of HIV. DNA SEQUENCE : THE JOURNAL OF DNA SEQUENCING AND MAPPING 1996; 6:119-21. [PMID: 8907308 DOI: 10.3109/10425179609010198] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
A motif search for DNA and mRNA sequences matching the rev response core element of HIV identified only DNA ligase I to display the element both in DNA and mRNA and to have phylogenetic conservation of it. Genetic impairment of DNA ligase I is already known to lead to severe immunodeficiency in man. A similar impairment may result from HIV rev protein binding to the DNA ligase I mRNA.
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Affiliation(s)
- T Dandekar
- European Molecular Biology Laboratory, Heidelberg, Germany
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