Name: quantification of the abundance and charging levels of transfer rnas in escherichia coli
Uploaded: 2017-08-22T14:00:00.000+00:00
Duration: 10 min 34 s
Description: Watch this Scientific Journal Video about Quantification of the Abundance and Charging Levels of Transfer RNAs in Escherichia coli at JoVE.com

Los autores agradecen a Marit Warrer excelente asistencia técnica. Este trabajo fue financiado por el Consejo Danés de investigación independiente | Ciencias naturales [1323-00343B] y la Fundación Nacional Danés de investigación [DNRF120].

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	<li>Varshney, U., Lee, C. -. P., RajBhandary, U. L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Direct+analysis+of+aminoacylation+levels+of+tRNAs+in+vivo.+Application+to+studying+recognition+of+Escherichia+coli+initiator+tRNA+mutants+by+glutaminyl-tRNA+synthetase.">Direct analysis of aminoacylation levels of tRNAs in vivo. Application to studying recognition of Escherichia coli initiator tRNA mutants by glutaminyl-tRNA synthetase.</a> J Biol Chem. 266 (36), 24712-24718 (1991).</li><li>Sorensen, M. 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A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Transfer+RNA+is+highly+unstable+during+early+amino+acid+starvation+in+Escherichia+coli.">Transfer RNA is highly unstable during early amino acid starvation in Escherichia coli.</a> Nucleic Acids Res. 45 (2), 793-804 (2017).</li><li>Enriquez, J. A., Attardi, G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Evidence+for+aminoacylation-induced+conformational+changes+in+human+mitochondrial+tRNAs.">Evidence for aminoacylation-induced conformational changes in human mitochondrial tRNAs.</a> Proc Natl Acad Sci U S A. 93 (16), 8300-8305 (1996).</li><li>Parker, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Errors+and+alternatives+in+reading+the+universal+genetic+code.">Errors and alternatives in reading the universal genetic code.</a> Microbiol Rev. 53 (3), 273-298 (1989).</li><li>Traxler, M. F., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+global,+ppGpp-mediated+stringent+response+to+amino+acid+starvation+in+Escherichia+coli.">The global, ppGpp-mediated stringent response to amino acid starvation in Escherichia coli.</a> Mol Microbiol. 68 (5), 1128-1148 (2008).</li><li>Zhong, J., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Transfer+RNAs+Mediate+the+Rapid+Adaptation+of+Escherichia+coli+to+Oxidative+Stress.">Transfer RNAs Mediate the Rapid Adaptation of Escherichia coli to Oxidative Stress.</a> PLoS Genet. 11 (6), e1005302 (2015).</li><li>Kane, J. F. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Effects+of+rare+codon+clusters+on+high-level+expression+of+heterologous+proteins+in+Escherichia+coli.">Effects of rare codon clusters on high-level expression of heterologous proteins in Escherichia coli.</a> Curr Opin Biotechnol. 6 (5), 494-500 (1995).</li><li>Baca, A. M., Hol, W. G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Overcoming+codon+bias:+a+method+for+high-level+overexpression+of+Plasmodium+and+other+AT-rich+parasite+genes+in+Escherichia+coli.">Overcoming codon bias: a method for high-level overexpression of Plasmodium and other AT-rich parasite genes in Escherichia coli.</a> Int J Parasitol. 30 (2), 113-118 (2000).</li><li>Li, S., Pelka, H., Schulman, L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+anticodon+and+discriminator+base+are+important+for+aminoacylation+of+Escherichia+coli+tRNA+(Asn).">The anticodon and discriminator base are important for aminoacylation of Escherichia coli tRNA (Asn).</a> J Biol Chem. 268 (24), 18335-18339 (1993).</li><li>Rizzino, A. A., Freundlich, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Estimation+of+in+vivo+aminoacylation+by+periodate+oxidation:+tRNA+alterations+and+iodate+inhibition.">Estimation of in vivo aminoacylation by periodate oxidation: tRNA alterations and iodate inhibition.</a> Anal Biochem. 66 (2), 446-449 (1975).</li><li>Dittmar, K. A., Sorensen, M. A., Elf, J., Ehrenberg, M., Pan, T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Selective+charging+of+tRNA+isoacceptors+induced+by+amino-acid+starvation.">Selective charging of tRNA isoacceptors induced by amino-acid starvation.</a> EMBO Rep. 6 (2), 151-157 (2005).</li><li>Zhou, K., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Novel+reference+genes+for+quantifying+transcriptional+responses+of+Escherichia+coli+to+protein+overexpression+by+quantitative+PCR.">Novel reference genes for quantifying transcriptional responses of Escherichia coli to protein overexpression by quantitative PCR.</a> BMC Mol Biol. 12 (1), 18 (2011).</li><li>Jacobson, A., Gillespie, D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Metabolic+events+occurring+during+recovery+from+prolonged+glucose+starvation+in+Escherichia+coli.">Metabolic events occurring during recovery from prolonged glucose starvation in Escherichia coli.</a> J Bacteriol. 95 (3), 1030-1039 (1968).</li><li>McCarthy, B. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+effects+of+magnesium+starvation+on+the+ribosome+content+of+Escherichia+coli.">The effects of magnesium starvation on the ribosome content of Escherichia coli.</a> Biochim Biophys Acta (BBA)-Specialized Section on Nucleic Acids and Related Subjects. 55 (6), 880-889 (1962).</li><li>Zundel, M. A., Basturea, G. N., Deutscher, M. P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Initiation+of+ribosome+degradation+during+starvation+in+Escherichia+coli.">Initiation of ribosome degradation during starvation in Escherichia coli.</a> Rna. 15 (5), 977-983 (2009).</li><li>Piir, K., Paier, A., Liiv, A., Tenson, T., Maivali, U. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Ribosome+degradation+in+growing+bacteria.">Ribosome degradation in growing bacteria.</a> EMBO Rep. 12 (5), 458-462 (2011).</li><li>Schaechter, M., Maaloe, O., Kjeldgaard, N. O. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Dependency+on+medium+and+temperature+of+cell+size+and+chemical+composition+during+balanced+grown+of+Salmonella+typhimurium.">Dependency on medium and temperature of cell size and chemical composition during balanced grown of Salmonella typhimurium.</a> J Gen Microbiol. 19 (3), 592-606 (1958).</li><li>Neidhardt, F. C., Bloch, P. L., Smith, D. F. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Culture+medium+for+enterobacteria.">Culture medium for enterobacteria.</a> J Bacteriol. 119 (3), 736-747 (1974).</li><li>Sambrook, J., Fritsch, E. F., Maniatis, T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> Molecular cloning: a laboratory manual. , (1989).</li><li>Sorensen, M. A., Jensen, K. F., Pedersen, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=High+concentrations+of+ppGpp+decrease+the+RNA+chain+growth+rate.+Implications+for+protein+synthesis+and+translational+fidelity+during+amino+acid+starvation+in+Escherichia+coli.">High concentrations of ppGpp decrease the RNA chain growth rate. Implications for protein synthesis and translational fidelity during amino acid starvation in Escherichia coli.</a> J Mol Biol. 236 (2), 441-454 (1994).</li><li>Tian, C., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Rapid+Curtailing+of+the+Stringent+Response+by+Toxin-Antitoxin+Module-Encoded+mRNases.">Rapid Curtailing of the Stringent Response by Toxin-Antitoxin Module-Encoded mRNases.</a> J Bacteriol. 198 (14), 1918-1926 (2016).</li></ol>

Los autores no tienen nada que revelar.

Este protocolo describe cómo medir simultáneamente el nivel de carga de concreto e. coli tRNAs y comparar los niveles relativos de los tRNAs en diferentes muestras. Son los puntos críticos del protocolo 1) manejar las muestras de tal manera que se mantienen los niveles de carga celular tRNA, 2) para normalizar la cantidad de tRNA de tal manera que pueden compararse confiablemente niveles relativos del tRNA en diferentes muestras y 3) para el sp ecificity de las sondas seleccionadas para los tRNAs de interés....

A continuación, presentamos un método para cuantificar el ARNt específico y medir su carga niveles por borrar norteño. El método se basa en una técnica desarrollada por Varshney et al. 1. recolección de las células en ácido tricloroacético (TCA) y manteniendo las muestras a 0 ° C a lo largo de la purificación de RNA, el enlace éster entre el tRNA y el aminoácido es conservado2,3,4. TRNAs Aminoacylated pueden distinguirse de sus contrapartes nonacylated por electroforesis y blotting norte, debido a una movilidad disminuida de la aminoacylated tRNA en el gel, causado por el ácido amino covalentemente5. Además, presentamos un protocolo para normalizar la cantidad de tRNA por adición de spike en células overexpressing el tRNA raramente usadoselC 4.
tRNAs son algunas de las moléculas más abundantes en la célula bacteriana y una parte esencial de la maquinaria de traducción. tRNAs unen aminoácidos y transfieren a los ribosomas traduciendo. La Unión de aminoácidos para tRNAs (aminoacilación o carga) facilita el aminoacil tRNA sintetasas. La abundancia relativa de diferentes tRNAs cargados es importante para asegurar la fidelidad de la síntesis de proteínas, debido a insuficiente representación del cognado cargado que tRNA para un codón determinado ARN mensajero (ARNm) aumenta la probabilidad de que un tRNA cerca de cognado entregar erróneamente su aminoácido a la cadena polipeptídica creciente en el ribosoma6. La importancia del tRNA cargado se refleja en la amplia respuesta de la célula de e. coli a una severa caída en los niveles de carga de un tRNA; la respuesta estricta. Durante la respuesta estricta disminuye la síntesis de ARNt, ARN ribosómico y mRNAs mayoría a favor de la transcripción de los mRNAs específicos asociados con aminoácido biosíntesis y estrés de supervivencia, y disminuye drásticamente la tasa de crecimiento de las células7 . Además, trabajos recientes y otros ha demostrado que e. coli activamente degrada a la mayoría de su tRNA en respuesta a las tensiones que limitan la traducción4,8, sugiriendo que puede ser el ajuste de los niveles de tRNA importante para hacer frente a dichas tensiones. Así, mediciones fiables de abundancias del tRNA y los niveles de carga será una herramienta importante para comprender plenamente las respuestas de estrés bacteriano.
E. coli se utiliza comúnmente para expresar proteínas recombinantes y debido a las diferencias en la utilización de codones entre especies, expresión óptima es un problema a menudo9. Esto puede eludirse por expresión de tRNAs adicionales necesarios para traducir el mRNA recombinante10. Las medidas de tRNA carga niveles en estas cepas podrían guiar los esfuerzos de solución de problemas y ayudar a optimizar la expresión de la proteína.
Este método también permite la detección de "confusiones"; un aminoacylated de molécula de ARNt con un aminoácido no cognado. Aminoacilación por diferentes aminoácidos puede causar un tRNA migrar con velocidades ligeramente diferentes a través de geles de poliacrilamida1,11. En algunos casos, el método también puede utilizarse para distinguir patrones de modificación diferentes tRNAs idéntico3.
Otro había establecido procedimiento bioquímico para la investigación del tRNA carga niveles es periodato de oxidación. El método se basa en la observación que aminoacylated tRNA está protegido de periodato de oxidación y tRNA descargada no es. Después periodato de tratamiento de la oxidación la recarga de los tRNA se utiliza para estimar los niveles de carga del ARN cosechado. Sin embargo, la recarga de varios tRNAs se ha demostrado para ser afectado por el tratamiento proporcionando alguna inexactitud12. El método presentado aquí medidas de carga directamente del RNA purificado, excluyendo así cualquier sesgo de reacciones químicas o enzimáticas. Una limitación de este método es que sólo una especie de tRNA se detecta a la vez, aunque el mismo Northern blot puede ser despojado y reprobed para varios tRNAs, es lento y algo laborioso recopilar datos sobre muchos tRNAs.
Una manera confiable de normalización de las muestras entre sí es vital en los estudios donde el objetivo es comparar los niveles relativos de una molécula a través de diferentes muestras. Aquí presentamos un procedimiento de normalización para RNA donde una pequeña alícuota de e. coli las células overexpressing el tRNA raraselC se agrega como un punto en a todas las muestras experimentales antes de la purificación del ARN. Este método es útil no sólo al examinar tRNAs pero para la cuantificación relativa de cualquier especie de ARN cuando la configuración experimental es tal que no RNA endógeno puede confiar que presentan en la misma concentración celular en todas las muestras. Por ejemplo, el nivel de una "limpieza" del ARN ribosómico RNA-como a menudo se utiliza como una referencia endógena para comparar las cantidades relativas de otro ARN entre diferentes muestras13. Pero esto es de poca utilidad si la concentración celular de la RNA de referencia varía entre las muestras, como puede ser el caso de ARN ribosómico si muestreo ocurre durante un estrés respuesta15,16,17 o entrada en fase estacionaria17. La adición de spike en células en las muestras experimentales antes de purificación de RNA proporciona una forma sólida y precisa de normalización independiente de la configuración de muestreo. Otra forma de normalización es la adición de uno o más punto en RNAs a las muestras experimentales después de la purificación de RNA. Sin embargo, este método no tiene en cuenta para las diferencias en la recuperación de RNA entre muestras.
Usando células de e. coli que sobrexpresan la referencia RNA como spike-en las células (ver figura 1) en un experimento de e. coli tiene el inconveniente que resulta además de una pequeña cantidad de exógena e. coli total de RNA para la muestras. Se corrigen para esta incorporación mediante el análisis de una muestra que contiene solamente spike en células en paralelo con las muestras experimentales (véase el Northern blot en carril figura 2, con la etiqueta "selC"). El protocolo que se presenta está desarrollado para e. coli K-12 pero es probable que sea aplicable para la mayoría de las especies bacteriana.

<table><tbody><tr><td>Urea</td><td>Merck</td><td>57-13-6</td><td>Purity &gt;99%</td></tr><tr><td>Polyacrylamide</td><td>Serva</td><td>79-06-7</td><td></td></tr><tr><td>Bis (N,N&#039;-Methylene-bis-acrylamide)</td><td>BIO-RAD</td><td>161-0201</td><td></td></tr><tr><td>Trichloroacetic acid (TCA)</td><td>Sigma</td><td>76-03-9</td><td></td></tr><tr><td>Phenol</td><td>Merck</td><td>108-95-2</td><td></td></tr><tr><td>IPTG</td><td></td><td></td><td></td></tr><tr><td>Glucose</td><td></td><td></td><td></td></tr><tr><td>Sodium Acetate</td><td></td><td></td><td></td></tr><tr><td>EDTA</td><td></td><td></td><td></td></tr><tr><td>Ethanol</td><td></td><td></td><td></td></tr><tr><td>Tris</td><td></td><td></td><td></td></tr><tr><td>Hydrochloric acid</td><td></td><td></td><td></td></tr><tr><td>Sodium Chloride</td><td></td><td></td><td></td></tr><tr><td>NaH2PO4</td><td></td><td></td><td></td></tr><tr><td>Sodium Citrate</td><td></td><td></td><td></td></tr><tr><td>SDS</td><td></td><td></td><td></td></tr><tr><td>Herring Sperm DNA</td><td>Sigma</td><td>100403-24-5</td><td></td></tr><tr><td>BSA</td><td></td><td></td><td></td></tr><tr><td>Polivinylpyrrolidone</td><td></td><td></td><td></td></tr><tr><td>Ficoll</td><td></td><td></td><td></td></tr><tr><td>P32 &amp;gamma;ATP</td><td>Perkin Elmer</td><td></td><td></td></tr><tr><td>DNA oligos (probes)</td><td>TAG Copenhagen</td><td></td><td></td></tr><tr><td>Hybond N&lt;sup&gt;+&lt;/sup&gt; membrane</td><td>GE Healthcare</td><td>RPN203B</td><td></td></tr><tr><td>Crosslinker</td><td></td><td></td><td></td></tr><tr><td>Electroblotter</td><td>BIO-RAD</td><td></td><td></td></tr><tr><td>Typhoon FLA 7000 Scanner</td><td>GE Healthcare</td><td>28955809</td><td></td></tr><tr><td>Spectrophotometer</td><td></td><td></td><td></td></tr><tr><td>Hydridization oven</td><td></td><td></td><td></td></tr><tr><td>Geiger-M&amp;uuml;ller tube</td><td></td><td></td><td></td></tr><tr><td>Phosphor imager screen</td><td>GE Healthcare</td><td></td><td></td></tr><tr><td>Hybridization tube</td><td></td><td></td><td></td></tr><tr><td>Culture Flasks</td><td></td><td></td><td></td></tr><tr><td>1.5 ml microcentrifuge tubes</td><td></td><td></td><td></td></tr><tr><td>20 ml centrifuge tubes</td><td></td><td></td><td></td></tr><tr><td>&lt;strong&gt;Name&lt;/strong&gt;</td><td>&lt;strong&gt;Company&lt;/strong&gt;</td><td>&lt;strong&gt;Catalog Number&lt;/strong&gt;</td><td>&lt;strong&gt;Comments&lt;/strong&gt;</td></tr><tr><td>&lt;strong&gt;Software&lt;/strong&gt;</td><td></td><td></td><td></td></tr><tr><td>ImageQuant</td><td>GE Healthcare</td><td></td><td></td></tr><tr><td>Excel</td><td>Microsoft</td><td></td><td></td></tr></tbody></table>

quantification of the abundance and charging levels of transfer rnas in escherichia coli

ARN de transferencia (tRNA) es una parte esencial de la maquinaria traduccional en cualquier organismo. ARNt se unen y transferir los aminoácidos al ribosoma traduciendo. Los niveles relativos de tRNAs distintos y la proporción de aminoacylated tRNA al tRNA total, conocido como el nivel de carga, son factores importantes en la determinación de la exactitud y velocidad de traducción. Por lo tanto, la abundancia y niveles de carga de tRNAs son variables importantes a medir en el estudio de la síntesis de proteínas, por ejemplo en diversas condiciones de estrés. Aquí, describimos un método para cosechar tRNA y medición directa de la abundancia relativa y el nivel absoluto de la carga de la especie específica del ARNt en Escherichia coli. El tRNA se recolecta de tal manera que se conserve el vínculo inestable entre el ARNt y su aminoácido. El RNA entonces se somete a electroforesis en gel y Northern Blot, que resulta en la separación de los tRNAs cargados y descargados. Los niveles de tRNAs específicos en diferentes muestras se pueden comparar debido a la adición de espiga en las células para la normalización. Antes de la purificación del ARN, agregamos 5% de células de e. coli que sobreproducción la tRNA raraselC a cada muestra. La cantidad de las especies de tRNA de interés en una muestra luego se normaliza la cantidad de tRNAselC en la misma muestra. Además de la espiga en las células antes de la purificación del ARN tiene la ventaja sobre adición de purificada spike en RNAs que también explica las diferencias en la eficiencia de la lisis de células entre las muestras.

Utilizando el procedimiento descrito aquí, la abundancia y carga se miden los niveles de tres tRNAs en e. coli K-12 antes y durante el hambre de aminoácidos.
El auxotroph arginina cepa NF9154 (leu thr su argH thi mtl supE44) se cultivaba durante al menos diez generaciones en MOPS medio mínimo suplementado con 0.4% de glicerol, 50 treonina μg/mL, leucina, arginina e histidina 5 μg/mL...

Watch this Scientific Journal Video about Quantification of the Abundance and Charging Levels of Transfer RNAs in Escherichia coli at JoVE.com

Quantification of the Abundance and Charging Levels of Transfer RNAs in Escherichia coli

Cuantificación de la abundancia y la carga de los niveles de ARN de transferencia en Escherichia coli

Aquí presentamos un método para medir directamente el ARN de transferencia carga niveles de purificada de Escherichia coli RNA como una forma de comparar niveles relativos de ARN de transferencia, o cualquier otro RNA corto, a través de diferentes muestras basadas en la adición de espiga en células expresan un gen de referencia.

Transfer RNA (tRNA) is an essential part of the translational machinery in any organism. tRNAs bind and transfer amino acids to the translating ribosome. ...

quantification-abundance-charging-levels-transfer-rnas-escherichia

Research

JoVE Journal

Biochemistry

Quantification of the Abundance and Charging Levels of Transfer RNAs in Escherichia coli

9.2K vistas.  University of Copenhagen. Aquí presentamos un método para medir directamente el ARN de transferencia carga niveles de purificada de Escherichia coli RNA como una forma de comparar niveles relativos de ARN de transferencia, o cualquier otro RNA corto, a través de diferentes muestras basadas en la adición de espiga en células expresan un gen de referencia.

Video: Quantification of the Abundance and Charging Levels of Transfer RNAs in Escherichia coli

Protein-tRNA Agarose Gel Retardation Assays for the Analysis of the N6-threonylcarbamoyladenosine TcdA Function

We demonstrate methods for the expression and purification of tRNA(UUU) in Escherichia coli and the analysis by gel retardation assays of the binding of tRNA(UUU) to TcdA, an N6-threonylcarbamoyladenosine (t6A) dehydratase, which cyclizes the threonylcarbamoyl side chain attached to A37 in the anticodon stem loop (ASL) of tRNAs to cyclic t6A (ct6A). Transcription of the synthetic gene encoding tRNA(UUU) is induced in E. coli with 1 mM isopropyl &#946;-D-1-thiogalactopyranoside (IPTG) and the cells containing tRNA are harvested 24 h post-induction. The RNA fraction is purified using the acid phenol extraction method. Pure tRNA is obtained by a gel filtration chromatography that efficiently separates the small-sized tRNA molecules from larger intact or fragmented nucleic acids. To analyze TcdA binding to tRNA(UUU), TcdA is mixed with tRNA(UUU) and separated on a native agarose gel at 4 &#176;C. The free tRNA(UUU) migrates faster, while the TcdA-tRNA(UUU) complexes undergo a mobility retardation that can be observed upon staining of the gel. We demonstrate that TcdA is a tRNA(UUU)-binding enzyme. This gel retardation assay can be used to study TcdA mutants and the effects of additives and other proteins on binding.

Protein-tRNA Agarose Gel Retardation Assays for the Analysis of the N6-threonylcarbamoyladenosine TcdA Function

A protocol is presented for the production of tRNA(UUU) and the analysis of tRNA(UUU) in complex with the enzyme TcdA by agarose gel retardation assays.

Ensayos de Retardo de Gel de ARNt de Proteína-ARNt para el Análisis del<emN</em<sup6</sup&gt; -threonylcarbamoyladenosine TcdA Function

We demonstrate methods for the expression and purification of tRNA(UUU) in Escherichia coli and the analysis by gel retardation assays of the binding of ...

Investigación

Bioquímica

Simultaneous DNA-RNA Extraction from Coastal Sediments and Quantification of 16S rRNA Genes and Transcripts by Real-time PCR

Real Time Polymerase Chain Reaction also known as quantitative PCR (q-PCR) is a widely used tool in microbial ecology to quantify gene abundances of taxonomic and functional groups in environmental samples. Used in combination with a reverse transcriptase reaction (RT-q-PCR), it can also be employed to quantify gene transcripts. q-PCR makes use of highly sensitive fluorescent detection chemistries that allow quantification of PCR amplicons during the exponential phase of the reaction. Therefore, the biases associated with &#39;end-point&#39; PCR detected in the plateau phase of the PCR reaction are avoided. A protocol to quantify bacterial 16S rRNA genes and transcripts from coastal sediments via real-time PCR is provided. First, a method for the co-extraction of DNA and RNA from coastal sediments, including the additional steps required for the preparation of DNA-free RNA, is outlined. Second, a step-by-step guide for the quantification of 16S rRNA genes and transcripts from the extracted nucleic acids via q-PCR and RT-q-PCR is outlined. This includes details for the construction of DNA and RNA standard curves. Key considerations for the use of RT-q-PCR assays in microbial ecology are included.

A protocol to quantify bacterial 16S rRNA genes and transcripts from coastal sediments via real-time PCR is provided. The methodology includes the co-extraction of DNA and RNA; preparation of DNA-free RNA; and 16S rRNA gene and transcript quantification via RT-q-PCR, including standard curve construction.

ADN-ARN simultánea extracción de los sedimentos costeros y cuantificación de 16S rRNA genes y las transcripciones de PCR en tiempo real

Real Time Polymerase Chain Reaction also known as quantitative PCR (q-PCR) is a widely used tool in microbial ecology to quantify gene abundances of ...

Medio ambiente

Real-time Analysis of Transcription Factor Binding, Transcription, Translation, and Turnover to Display Global Events During Cellular Activation

Upon activation, cells rapidly change their functional programs and, thereby, their gene expression profile. Massive changes in gene expression occur, for example, during cellular differentiation, morphogenesis, and functional stimulation (such as activation of immune cells), or after exposure to drugs and other factors from the local environment. Depending on the stimulus and cell type, these changes occur rapidly and at any possible level of gene regulation. Displaying all molecular processes of a responding cell to a certain type of stimulus/drug is one of the hardest tasks in molecular biology. Here, we describe a protocol that enables the simultaneous analysis of multiple layers of gene regulation. We compare, in particular, transcription factor binding (Chromatin-immunoprecipitation-sequencing (ChIP-seq)), de novo transcription (4-thiouridine-sequencing (4sU-seq)), mRNA processing, and turnover as well as translation (ribosome profiling). By combining these methods, it is possible to display a detailed and genome-wide course of action.
Sequencing newly transcribed RNA is especially recommended when analyzing rapidly adapting or changing systems, since this depicts the transcriptional activity of all genes during the time of 4sU exposure (irrespective of whether they are up- or downregulated). The combinatorial use of total RNA-seq and ribosome profiling additionally allows the calculation of RNA turnover and translation rates. Bioinformatic analysis of high-throughput sequencing results allows for many means for analysis and interpretation of the data. The generated data also enables tracking co-transcriptional and alternative splicing, just to mention a few possible outcomes.
The combined approach described here can be applied for different model organisms or cell types, including primary cells. Furthermore, we provide detailed protocols for each method used, including quality controls, and discuss potential problems and pitfalls.

This protocol describes the combinatorial use of ChIP-seq, 4sU-seq, total RNA-seq, and ribosome profiling for cell lines and primary cells. It enables tracking changes in transcription-factor binding, de novo transcription, RNA processing, turnover and translation over time, and displaying the overall course of events in activated and/or rapidly changing cells.

Análisis en tiempo real del Factor de transcripción vinculante, transcripción, traducción y rotación para mostrar los eventos globales durante la activación celular

Upon activation, cells rapidly change their functional programs and, thereby, their gene expression profile. Massive changes in gene expression occur, for ...

Genética

Metabolic Labeling and Profiling of Transfer RNAs Using Macroarrays

Transfer RNAs (tRNA) are abundant short non-coding RNA species that are typically 76 to 90 nucleotides in length. tRNAs are directly responsible for protein synthesis by translating codons in mRNA into amino acid sequences. tRNAs were long considered as house-keeping molecules that lacked regulatory functions. However, a growing body of evidence indicates that cellular tRNA levels fluctuate in correspondence to varying conditions such as cell type, environment, and stress. The fluctuation of tRNA expression directly influences gene translation, favoring or repressing the expression of particular proteins. Ultimately comprehending the dynamic of protein synthesis requires the development of methods able to deliver high-quality tRNA profiles. The method that we present here is named SPOt, which stands for Streamlined Platform for Observing tRNA. SPOt consists of three steps starting with metabolic labeling of cell cultures with radioactive orthophosphate, followed by guanidinium thiocyanate-phenol-chloroform extraction of radioactive total RNAs and finally hybridization on in-house printed macroarrays. tRNA levels are estimated by quantifying the radioactivity intensities at each probe spot. In the protocol presented here we profile tRNAs in Mycobacterium smegmatis mc2155, a nonpathogenic bacterium often used as a model organism to study tuberculosis.

We describe an original transfer RNA analysis platform named SPOt (Streamlined Platform for Observing tRNA). SPOt simultaneously measures cellular levels of all tRNAs in biological samples, in only three steps, and in less than 24 hours.

Etiquetado metabólico y perfiles de RNAs de transferencia utilizando Macroarrays

Transfer RNAs (tRNA) are abundant short non-coding RNA species that are typically 76 to 90 nucleotides in length. tRNAs are directly responsible for ...

An Assay for Quantifying Protein-RNA Binding in Bacteria

In the initiation step of protein translation, the ribosome binds to the initiation region of the mRNA. Translation initiation can be blocked by binding of an RNA binding protein (RBP) to the initiation region of the mRNA, which interferes with ribosome binding. In the presented method, we utilize this blocking phenomenon to quantify the binding affinity of RBPs to their cognate and non-cognate binding sites. To do this, we insert a test binding site in the initiation region of a reporter mRNA and induce the expression of the test RBP. In the case of RBP-RNA binding, we observed a sigmoidal repression of the reporter expression as a function of RBP concentration. In the case of no-affinity or very low affinity between binding site and RBP, no significant repression was observed. The method is carried out in live bacterial cells, and does not require expensive or sophisticated machinery. It is useful for quantifying and comparing between the binding affinities of different RBPs that are functional in bacteria to a set of designed binding sites. This method may be inappropriate for binding sites with high structural complexity. This is due to the possibility of repression of ribosomal initiation by complex mRNA structure in the absence of RBP, which would result in lower basal reporter gene expression, and thus less-observable reporter repression upon RBP binding.

In this method, we quantify the binding affinity of RNA binding proteins (RBPs) to cognate and non-cognate binding sites using a simple, live, reporter assay in bacterial cells. The assay is based on repression of a reporter gene.

Un ensayo para cuantificar la unión de proteínas y ARN en bacterias

In the initiation step of protein translation, the ribosome binds to the initiation region of the mRNA. Translation initiation can be blocked by binding ...

Análisis de la dinámica del ARNt mediante AQRNA-seq

AQRNA-seq for Quantifying Small RNAs

AQRNA-seq provides a direct linear relationship between sequencing read counts and small RNA copy numbers in a biological sample, thus enabling accurate quantification of the pool of small RNAs. The AQRNA-seq library preparation procedure described here involves the use of custom-designed sequencing linkers and a step for reducing methylation RNA modifications that block reverse transcription processivity, which results in an increased yield of full-length cDNAs. In addition, a detailed implementation of the accompanying bioinformatics pipeline is presented. This demonstration of AQRNA-seq was conducted through a quantitative analysis of the 45 tRNAs in Mycobacterium bovis BCG harvested on 5 selected days across a 20-day time course of nutrient deprivation and 6 days of resuscitation. Ongoing efforts to improve the efficiency and rigor of AQRNA-seq will also be discussed here. This includes exploring methods to obviate gel purification for mitigating primer dimer issues after PCR amplification and to increase the proportion of full-length reads to enable more accurate read mapping. Future enhancements to AQRNA-seq will be focused on facilitating automation and high-throughput implementation of this technology for quantifying all small RNA species in cell and tissue samples from diverse organisms.

Autor destacado: El papel de AQRNA-seq en el mapeo de ARN pequeños y el desentrañamiento de los mecanismos de traducción de proteínas

Absolute quantification RNA sequencing (AQRNA-seq) is a technology developed to quantify the landscape of all small RNAs in biological mixtures. Here, both the library preparation and data processing steps of AQRNA-seq are demonstrated, quantifying changes in the transfer RNA (tRNA) pool in Mycobacterium bovis BCG during starvation-induced dormancy.

AQRNA-seq para cuantificar ARNs pequeños

AQRNA-seq provides a direct linear relationship between sequencing read counts and small RNA copy numbers in a biological sample, thus enabling accurate ...

RIBO-seq in Bacteria: a Sample Collection and Library Preparation Protocol for NGS Sequencing

The ribosome profiling technique (RIBO-seq) is currently the most effective tool for studying the process of protein synthesis in vivo. The advantage of this method, in comparison to other approaches, is its ability to monitor translation by precisely mapping the position and number of ribosomes on a mRNA transcript.
In this article, we describe the consecutive stages of sample collection and preparation for RIBO-seq method in bacteria, highlighting the details relevant to the planning and execution of the experiment.
Since the RIBO-seq relies on intact ribosomes and related mRNAs, the key step is rapid inhibition of translation and adequate disintegration of cells. Thus, we suggest filtration and flash-freezing in liquid nitrogen for cell harvesting with an optional pretreatment with chloramphenicol to arrest translation in bacteria. For the disintegration, we propose grinding frozen cells with mortar and pestle in the presence of aluminum oxide to mechanically disrupt the cell wall. In this protocol, sucrose cushion or a sucrose gradient ultracentrifugation for monosome purification is not required. Instead, mRNA separation using polyacrylamide gel electrophoresis (PAGE) followed by the ribosomal footprint excision (28-30 nt band) is applied and provides satisfactory results. This largely simplifies the method as well as reduces the time and equipment requirements for the procedure. For library preparation, we recommend using the commercially available small RNA kit for Illumina sequencing from New England Biolabs, following manufacturer&#39;s guidelines with some degree of optimization.
The resulting cDNA libraries present appropriate quantity and quality required for next generation sequencing (NGS). Sequencing of the libraries prepared according to the described protocol results in 2 to 10 mln uniquely mapped reads per sample providing sufficient data for comprehensive bioinformatic analysis. The protocol we present is quick and relatively easy and can be performed with standard laboratory equipment.

Here we describe the stages of sample collection and preparation for RIBO-seq in bacteria. Sequencing of the libraries prepared according to these guidelines results in sufficient data for comprehensive bioinformatic analysis. The protocol we present is simple, uses standard laboratory equipment and takes seven days from lysis to obtaining libraries.

RIBO-seq En Bacterias: Una Colección de Muestras Y Protocolo De Preparación De La Biblioteca Para La Secuenciación NGS

The ribosome profiling technique (RIBO-seq) is currently the most effective tool for studying the process of protein synthesis in vivo. The advantage of ...

Genome-wide Analysis of Aminoacylation (Charging) Levels of tRNA Using Microarrays

tRNA aminoacylation, or charging, levels can rapidly change within a cell in response to the environment[1]. Changes in tRNA charging levels in both prokaryotic and eukaryotic cells lead to translational regulation which is a major cellular mechanism of stress response. Familiar examples are the stringent response in E. coli and the Gcn2 stress response pathway in yeast ([2-6]). Recent work in E. coli and S. cerevisiae have shown that tRNA charging patterns are highly dynamic and depends on the type of stress experienced by cells [1, 6, 7]. The highly dynamic, variable nature of tRNA charging makes it essential to determine changes in tRNA charging levels at the genomic scale, in order to fully elucidate cellular response to environmental variations. In this review we present a method for simultaneously measuring the relative charging levels of all tRNAs in S. cerevisiae . While the protocol presented here is for yeast, this protocol has been successfully applied for determining relative charging levels in a wide variety of organisms including E. coli and human cell cultures[7, 8].

Genome-wide Analysis of Aminoacylation Charging Levels of tRNA Using Microarrays

We describe a method for microarray analysis to determine relative aminoacylation levels of all tRNAs from S. cerivisiae.

Todo el genoma análisis de Aminoacilación (de carga) Niveles de tRNA utilizando microarrays

tRNA aminoacylation, or charging, levels can rapidly change within a cell in response to the environment[1]. Changes in tRNA charging levels in both ...

Cuantificación de la abundancia y la carga de los niveles de ARN de transferencia en Escherichia coli

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ADN-ARN simultánea extracción de los sedimentos costeros y cuantificación de 16S rRNA genes y las transcripciones de PCR en tiempo real

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Etiquetado metabólico y perfiles de RNAs de transferencia utilizando Macroarrays

Un ensayo para cuantificar la unión de proteínas y ARN en bacterias

AQRNA-seq para cuantificar ARNs pequeños

AQRNA-seq para cuantificar ARNs pequeños

AQRNA-seq para cuantificar ARNs pequeños

RIBO-seq En Bacterias: Una Colección de Muestras Y Protocolo De Preparación De La Biblioteca Para La Secuenciación NGS

Todo el genoma análisis de Aminoacilación (de carga) Niveles de tRNA utilizando microarrays