Name: rna catalyst as a reporter for screening drugs against rna editing in trypanosomes
Uploaded: 2014-07-22T13:00:00.000+00:00
Duration: 9 min 19 s
Description: Watch this Scientific Journal Video about RNA Catalyst as a Reporter for Screening Drugs against RNA Editing in Trypanosomes at JoVE.com

Najmeh Nikpour and Fiona Alum provided suggestions and edited this manuscript. Department of Biochemistry at McGill University supported HM and VM with the CIHR Training Initiative in Chemical Biology. This work was supported by Canadian Institute of Health Research (CIHR) grant 119464 (to R. S.).

Die folgende Protokoll beschreibt die Verfahren zur Durchführung der fluoreszenzbasierten Assays RNA-Editierung. Der Assay kann in einem PCR-Röhrchen, 96-Well-oder 384-Well-Platten in Abhängigkeit von dem Umfang des Experiments durchgeführt werden. Anschließend wird das Fluoreszenzsignal kann auf einem geeigneten Echtzeit-PCR-Nachweissystem gelesen werden. Der Assay wird hier im Zusammenhang mit der 384-Well-Platten beschrieben. 1. Kultivierung T. brucei Cells <ol><li> Bereiten Sie ein Wachstumsmedium für T. brucei prozyklischen Form Zellen. Für 1 l Medium: <ol><li> Lösen 25,4 g SDM-79-Pulver in 800 ml MilliQ-Wasser. </li><li> 2 g NaHCO 3 und pH-Wert auf 7,3 mit 10 M NaOH. </li><li> In Nanopure-Wasser auf ein Volumen von 900 ml, Filter zu sterilisieren. </li><li> Hinzufügen Fetal Bovine Serum (FBS), Penicillin-Streptomycin-Lösung und Hämin (2,5 mg / ml) bis zu Endkonzentrationen von 10% (v / v), 100 U / ml und 7,5 mg / l auf. </li></ol></li><li> Wachsen 300 ml T. &lt;em&gt; brucei 1.7A Wildtyp (prozyklischen Form)-Zellen bei 28 ° C, Schütteln bei 70 Umdrehungen pro Minute bis zu einer Dichte von 1,5 x 10 7 Zellen / ml. HINWEIS: Dies sollte 3 ml der aktiven editosome produzieren mit ~ 0,5 mg Gesamtprotein, ausreichend für 600 Bearbeitung Reaktionen. </li><li> Ernte der Zellen durch Zentrifugation bei 6.000 × g für 10 min bei 4 ° C. </li><li> Mit 50 ml gekühltem PBSG-Puffer (10 mM Na 2 HPO 4, 10 mM NaH 2 PO 4, 145 mM NaCl und 6 mM Glucose) Waschen des Pellets und Spin-down Zellen werden erneut durch Zentrifugation bei 10.000 × g für 10 min bei 4 ° C. </li></ol> 2. Isolierung von Mitochondrien Crude HINWEIS: Alle Schritte sollten auf Eis oder bei 4 ° C durchgeführt, um editosome Aktivität zu bewahren. <ol><li> Resuspendieren der geernteten Zellen in 30 ml DEE-Puffer (1 mM Tris-HCl pH 8,0 und 1 mM EDTA). Verwenden Sie eine 40 ml sterile Dounce Homogenisator (vorgekühlte), um die Zellmembran durch Streicheln auf und ab mindestens 10-mal auf Eis zu stören. </li&gt; <li> 4,3 ml 60% Saccharose (w / v, dh 1,75 M) unmittelbar in den Homogenat zu einer Endkonzentration von 0,25 M Zentrifugieren bei 15.800 × g für 10 min bei 4 ° C, bevorzugt zu bringen Mitochondrien. </li><li> Resuspendieren des Mitochondrienpellet in 4,6 ml STM-Puffer (20 mM Tris-HCl pH 8,0, 250 mM Saccharose und 2 mM MgCl 2). Hinzufügen 13,8 ul 0,1 M CaCl 2 und 4 &amp;mgr; l RNase-freier DNase I, um Endkonzentrationen von 0,3 mM und 9 U / ml. Inkubieren der Mischung für 1 Stunde auf Eis. </li><li> Hinzufügen von 4,6 ml STE-Puffer (20 mM Tris-HCl pH 8,0, 250 mM Saccharose und 2 mM EDTA), um das DNase I. Zentrifugieren bei 15.800 × g für 10 min bei 4 ° C inaktiviert </li><li> Das Pellet in 400 ul Lysepuffer (10 mM Tris-HCl pH 7,2, 10 mM MgCl 2, 100 mM KCl, 1 ug / ml Pepstatin, 1 mM DTT und 1x komplett EDTA-freie Protease-Inhibitor) und Übertragung auf eine Mikrozentrifugenröhrchen. </li><li> Hinzufügen von 10% Triton X-100 auf eine Endkonzentration von 1%nd bebrüten das Lysat für 15 min bei 4 ° C auf einem Schwenker. </li><li> Deaktivieren des mitochondrialen Lysat durch Zentrifugieren zweimal bei 17.000 × g für 15 min bei 4 ° C; Beibehaltung der geklärte Überstand jeder Zeit. </li></ol> 3. Editosome Reinigung <ol><li> Pour à 10 ml 10% -30% (v / v) Glycerin linearen Gradienten (Tabelle 1) in ein Ultrazentrifugenröhrchen mit 2x HHE Gradienten-Puffer (40 mM HEPES pH 7,9, 20 mM Mg (OAc) 2, 100 mM KCl, und 2 mM EDTA) und ein Gradient Maker, indem Sie die Gebrauchsanleitung. </li><li> Entfernen Sie vorsichtig 500 ul Lösung von der Spitze der Glycerin-Gradienten und schonend geladen werden 500 ul der mitochondrialen Lysat gelöscht. Schleudern bei 178.000 × g für 6 Stunden bei 4 º C unter Verwendung einer Ultrazentrifuge. </li><li> Sequentielles Sammeln 500 ul-Fraktionen von der Oberseite zum Boden des Gradienten bei 4 ° C. Dann schnappen Einfrieren der Fraktionen mit flüssigem Stickstoff und bei -80 ° C bis zur Nutzung. </li></ol><ol><li> Annealing der jeweiligen DNA-Matrize, die komplementäre Sequenz T7-Promotorsequenz (Tabelle 2) mit einem T7-Promotor-Oligonukleotid (5&#39;-TAATACGACTCACTATAGGG-3 &#39;) in einem Molverhältnis von 1:1 durch Erhitzen bei 90 ° C für 3 Minuten und Abkühlen auf RT für mindestens 10 min. </li><li> Transkribieren RNA mit Hilfe eines in-vitro-Transkription-Kit, indem Sie die Gebrauchsanleitung. </li><li> Stoppen Sie die Transkription Reaktion durch Zugabe von gleichen Volumen von 7 M Harnstoff-Farbstoff (7 M Harnstoff, 0,05% Xylol Cynol und 0,05% Bromphenolblau). Führen Sie auf einem Filter sterilisiert 9% denaturierenden Polyacrylamid-Gel (9% Acrylamid, 7 M Harnstoff, 1x TBE). </li><li> Verwenden Sie die Ultraviolett (UV)-Shadowing mit einem kurzwelligen UV-Lampe zu finden und Verbrauch jeweiligen RNA. Platzieren der ausgeschnittenen Gelstück in ein Mikrozentrifugenröhrchen und füge 400 ul Gel Elutionspuffer (20 mM Tris-HCl pH 7,5, 250 mM NaOAc, 1 mM EDTA und 0,25% SDS). Eluiere über Nacht bei RT auf einem Schwenker. </li><li> PreciPitate der eluierten RNA durch Zugabe von 1 ml kaltem 100% Ethanol und Inkubation entweder bei -80 ° C für 30 min und 20 ° C über Nacht. </li><li> Zentrifuge bei 16.000 × g für 30 min bei 4 ° C, um die RNA zu pelletieren unten. </li><li> Mit 1 ml 75% Ethanol Waschen des Pellets. Zentrifugieren bei 16000 × g für 20 min bei 4 ° C </li><li> Die RNA-Pellet in geeigneter Weise in RNase-freiem Wasser auf die gewünschten Konzentrationen zu erreichen, wie in Tabelle 2 gezeigt. </li></ol> 5. Fluoreszenz-basierte RNA-Editing-Assay <ol><li> Für einen Reaktions kombinieren 1 pmol (1 ul) preA6Rbz und 2,5 pmol (1 ul) gA6Rbz (Molverhältnis 1:2,5) in einem Mikrozentrifugenröhrchen, Inkubation bei 70 º C für 3 min und lassen Sie es bei RT sitzen an mindestens 10 min. </li><li> Unterdessen bereiten einen Master-Mix unter Verwendung von Tabelle 3, ohne preA6Rbz und gA6Rbz, für die Bearbeitung aus 1x HHE Reaktionspuffer (25 mM HEPES pH 7,9, 10 mM Mg (OAc) 2, 50 mM KCl und 10 mM EDTA), 1 mMATP, 5 mM CaCl 2, 16 ng / ul Torula-Hefe-RNA, 0,1% Triton X-100, und das gereinigte editosome. </li><li> In geglüht preA6Rbz und gA6Rbz, um den Master-Mix zu vervollständigen. </li><li> Verzichten 18 &amp;mgr; l der Mastermischung (Tabelle 3) in die Vertiefungen, die entweder 2 &amp;mgr; l RNase-freies Wasser (Vertiefungen ohne Verbindungen) oder 2 &amp;mgr; l 200 &amp;mgr; M chemischen Verbindungen und umfassen Kontrollproben in der Platte nach Fig. 5. </li><li> Verschließen Sie die Platte mit einem Plattenabdeckung und drehen Sie die Platte nach unten, um die Luftblasen zu entfernen. Inkubieren bei 28 ° C für 4 Stunden. </li><li> In 25 pmol (2 ul) gA6Rbz Wettbewerber in jede Vertiefung. Legen Sie eine frische Versiegelung, drehen Sie die Platte um und legen Sie es auf einer Echtzeit-PCR-Maschine. Programmieren Sie das folgende Experiment: Schritt 1: 85 ° C für 5 min; Schritt 2: 24 ° C für 10 min; Schritt 3: Stop. </li><li> Werden 15 pmol (1 ul) des FRET-Substrat zu jeder Vertiefung bis zu einem Endvolumen von 23 ul. Verschließen Sie die Platte mit einem frischen Versiegelung.Schnell drehen die Platte und legen Sie sie wieder auf die Echtzeit-PCR-Maschine. </li><li> Programmieren Sie einen neuen Versuch mit den folgenden Schritten: Schritt 1: 37 ° C für 1 min; Schritt 2: Lesen; Schritt 3: Gehen Sie auf 1, 40 mal Schritt; Schritt 4: Stop. </li><li> Setup die Platte, indem Sie alle Brunnen, die Lektüre erfordern, und wählen Sie den FAM-Filter. Eingangsvolumen 23 ul und den Lauf starten. </li><li> Berechnen Sie die Steigung der von jedem gut / Probe erhalten, um eine kinetische Messung durch Auftragen der Pisten auf einem Balkendiagramm für die Analyse zu erhalten Werte. HINWEIS: Eine kinetische Lese verbessert das Signal-Rausch-Verhältnis zwischen der Probe und dem Hintergrund; als der Hintergrund Probe würde eine Steigung nahe Null haben. Ein Endpunkt Lesen hat eine höhere Hintergrundgeräusche. </li></ol>

<ol>
	<li>Benne, R., 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=transcript+of+the+frameshifted+coxII+gene+from+trypanosome+mitochondria+contains+four+nucleotides+that+are+not+encoded+in+the+DNA.">transcript of the frameshifted coxII gene from trypanosome mitochondria contains four nucleotides that are not encoded in the DNA.</a> Cell. 46, 819-826 (1986).</li><li>Hajduk, S., Ochsenreiter, T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=RNA+editing+in+kinetoplastids.">RNA editing in kinetoplastids.</a> RNA biology. 7, 229-236 (2010).</li><li>Aphasizhev, R., Aphasizheva, I. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Uridine+insertion/deletion+editing+in+trypanosomes:+a+playground+for+RNA-guided+information+transfer.">Uridine insertion/deletion editing in trypanosomes: a playground for RNA-guided information transfer.</a> Wiley interdisciplinary reviews RNA. 2, 669-685 (2011).</li><li>Seiwert, S. D., Stuart, K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=RNA+editing:+transfer+of+genetic+information+from+gRNA+to+precursor+mRNA+in+vitro.">RNA editing: transfer of genetic information from gRNA to precursor mRNA in vitro.</a> Science. 266, 114-117 (1994).</li><li>Weng, 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=Guide+RNA-binding+complex+from+mitochondria+of+trypanosomatids.">Guide RNA-binding complex from mitochondria of trypanosomatids.</a> Molecular. 32, 198-209 (2008).</li><li>Hashimi, H., Zikova, A., Panigrahi, A. K., Stuart, K. D., Lukes, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=TbRGG1,+an+essential+protein+involved+in+kinetoplastid+RNA+metabolism+that+is+associated+with+a+novel+multiprotein+complex.">TbRGG1, an essential protein involved in kinetoplastid RNA metabolism that is associated with a novel multiprotein complex.</a> RNA. 14, 970-980 (2008).</li><li>Ammerman, M. L., 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=Architecture+of+the+trypanosome+RNA+editing+accessory+complex,+MRB1.">Architecture of the trypanosome RNA editing accessory complex, MRB1.</a> Nucleic Acids Res. 40, 5637-5650 (2012).</li><li>Huang, C. E., O'Hearn, S. F., Sollner-Webb, B. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Assembly+and+function+of+the+RNA+editing+complex+in+Trypanosoma+brucei+requires+band+III+protein.">Assembly and function of the RNA editing complex in Trypanosoma brucei requires band III protein.</a> Molecular and cellular biology. 22, 3194-3203 (2002).</li><li>Carnes, J., Trotter, J. R., Peltan, A., Fleck, M., Stuart, K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=RNA+editing+in+Trypanosoma+brucei+requires+three+different+editosomes.">RNA editing in Trypanosoma brucei requires three different editosomes.</a> Molecular and cellular biology. 28, 122-130 (2008).</li><li>Hearn, S. F., Huang, C. E., Hemann, M., Zhelonkina, A., Sollner-Webb, B. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Trypanosoma+brucei+RNA+editing+complex:+band+II+is+structurally+critical+and+maintains+band+V+ligase,+which+is+nonessential.">Trypanosoma brucei RNA editing complex: band II is structurally critical and maintains band V ligase, which is nonessential.</a> Molecular and cellular biology. 23, 7909-7919 (2003).</li><li>Schnaufer, A., 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=An+RNA+ligase+essential+for+RNA+editing+and+survival+of+the+bloodstream+form+of+Trypanosoma+brucei.">An RNA ligase essential for RNA editing and survival of the bloodstream form of Trypanosoma brucei.</a> Science. 291, 2159-2162 (2001).</li><li>Tarun, S. Z., 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=KREPA6+is+an+RNA-binding+protein+essential+for+editosome+integrity+and+survival+of+Trypanosoma+brucei.">KREPA6 is an RNA-binding protein essential for editosome integrity and survival of Trypanosoma brucei.</a> RNA. 14, 347-358 (2008).</li><li>Croft, S. L., Barrett, M. P., Urbina, J. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Chemotherapy+of+trypanosomiases+and+leishmaniasis.">Chemotherapy of trypanosomiases and leishmaniasis.</a> Trends in parasitology. 21, 508-512 (2005).</li><li>Denise, H., Barrett, 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=Uptake+and+mode+of+action+of+drugs+used+against+sleeping+sickness.">Uptake and mode of action of drugs used against sleeping sickness.</a> Biochemical pharmacology. 61, 1-5 (2001).</li><li>Seiwert, S. D., Heidmann, S., Stuart, K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Direct+visualization+of+uridylate+deletion+in+vitro+suggests+a+mechanism+for+kinetoplastid+RNA+editing.">Direct visualization of uridylate deletion in vitro suggests a mechanism for kinetoplastid RNA editing.</a> Cell. 84, 831-841 (1996).</li><li>Igo, R. P., Palazzo, S. S., Burgess, M. L., Panigrahi, A. K., Stuart, K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Uridylate+addition+and+RNA+ligation+contribute+to+the+specificity+of+kinetoplastid+insertion+RNA+editing.">Uridylate addition and RNA ligation contribute to the specificity of kinetoplastid insertion RNA editing.</a> Molecular and cellular biology. 20, 8447-8457 (2000).</li><li>Igo, R. P., 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=Role+of+uridylate-specific+exoribonuclease+activity+in+Trypanosoma+brucei+RNA+editing.">Role of uridylate-specific exoribonuclease activity in Trypanosoma brucei RNA editing.</a> Eukaryotic cell. 1, 112-118 (2002).</li><li>Wang, B., Salavati, R., Heidmann, S., Stuart, K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+hammerhead+ribozyme+substrate+and+reporter+for+in+vitro+kinetoplastid+RNA+editing.">A hammerhead ribozyme substrate and reporter for in vitro kinetoplastid RNA editing.</a> RNA. 8, 548-554 (2002).</li><li>Moshiri, H., Salavati, R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+fluorescence-based+reporter+substrate+for+monitoring+RNA+editing+in+trypanosomatid+pathogens.">A fluorescence-based reporter substrate for monitoring RNA editing in trypanosomatid pathogens.</a> Nucleic Acids Res. 38, e138 (2010).</li><li>Jenne, A., 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+identification+and+characterization+of+hammerhead-ribozyme+inhibitors+using+fluorescence-based+technology.">Rapid identification and characterization of hammerhead-ribozyme inhibitors using fluorescence-based technology.</a> Nature. 19, 56-61 (2001).</li><li>Hartig, J. S., 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=Protein-dependent+ribozymes+report+molecular+interactions+in+real+time.">Protein-dependent ribozymes report molecular interactions in real time.</a> Nature. 20, 717-722 (2002).</li><li>Famulok, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Allosteric+aptamers+and+aptazymes+as+probes+for+screening+approaches.">Allosteric aptamers and aptazymes as probes for screening approaches.</a> Current opinion in molecular therapeutics. 7, 137-143 (2005).</li><li>Teng, B., Burant, C. F., Davidson, 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=Molecular+cloning+of+an+apolipoprotein+B+messenger+RNA+editing+protein.">Molecular cloning of an apolipoprotein B messenger RNA editing protein.</a> Science. 260, 1816-1819 (1993).</li><li>Jurica, M. S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Searching+for+a+wrench+to+throw+into+the+splicing+machine.">Searching for a wrench to throw into the splicing machine.</a> Nature chemical biology. 4, 3-6 (2008).</li><li>Spahn, C., Prescott, C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Throwing+a+spanner+in+the+works:+antibiotics+and+the+translation+apparatus.">Throwing a spanner in the works: antibiotics and the translation apparatus.</a> Journal of molecular medicine. 74, 423-439 (1996).</li></ol>

The authors have nothing to disclose.

Ein neuartiges Hochdurchsatz-Screening-Verfahren, um Inhibitoren gegen die RNA-Editing-Komplex von Trypanosomen identifizieren vorgestellt wurde, bietet ein neues Werkzeug für die Wirkstoffforschung an Krankheiten, die durch Trypanosomatiden verursacht zu begegnen. FRET-basierten Ribozym Assay wurde ausgiebig für verschiedene Zwecke verwendet, 20-22; Jedoch haben wir die Fähigkeit von FRET-Ribozym-Assay für die in vitro Überwachung der RNA-Editing Aktivität 19 verwendet. Dieser Test ...

Der Prozess der RNA-Editing, ein Post-Transkriptions mRNA Änderung, wurde zuerst in Trypanosomatiden 1 entdeckt. Seitdem hat umfangreiche Arbeit bei der Untersuchung der Mechanismus hinter RNA-Editing in Trypanosoma brucei 2,3 durchgeführt. In einer Reihe von enzymatischen Reaktionen, die editosome ein Kernkomplex von etwa 20 Proteinen, erstellt reifen mitochondrialen mRNAs für mehrere Komponenten der oxidativen Phosphorylierung Energieerzeugungssystems. Die Reihenfolge der Ereignisse ist endonukleolytische katalytische Spaltung Uridylat (U) Hinzufügen oder Löschen, und Ligation, wie durch Führungs RNAs (gRNAs) diktiert 4. Neben den Kern editosome komplexe Proteine ​​haben eine Reihe von Hilfsfaktoren auch identifiziert 5-7. Diese Proteine ​​sind meist gesehen in unabhängigen Komplexen gruppiert. Jedoch ist die Reihenfolge der Proteinanordnung in den Kern editosome komplex und die Interaktionsmuster des Kernkomplex mit dem ZubehörKomplexe noch bestimmt werden. Targeting der RNA-Editing-Prozess in Trypanosomatiden können chemische Dissectoren sorgen, dass die Hilfe bei der Untersuchung der Montage und Funktion der editosome komplex. Darüber hinaus haben funktionelle Untersuchungen auf mehreren editosome Proteine ​​Wesentlichkeit in verschiedenen Lebensphasen dargestellt, was auf ihr Potenzial als Medikament zielt 12.08. Daher kann die gefundenen Inhibitoren der editosome auch als Bleiverbindungen gegen Trypanosomatiden handeln. Dies ist an der Zeit, wie sie derzeit gegen Krankheiten, die durch Trypanosomatida verursacht verfügbaren Medikamente sind giftig, ineffizient und teuer 13,14. Eine effiziente und bequeme in-vitro-Test ist notwendig, um die chemische Universum für spezifische Inhibitoren, RNA-Editing blockieren erkunden. Drei Tests wurden entwickelt und verwendet werden, um Aktivitäten zu überwachen editosome: (a) volle Runde in vitro RNA-Editing-Test 15, (b) in vitro RNA-Editing-Assay 16,17, vorge gespalten einnd (c) Hammerhead-Ribozym (HHR) basierenden Assay 18. Die ersten beiden Tests beruhen auf direkte Visualisierung des bearbeiteten Produktes (6 ATPase mRNA) mit Hilfe von Radioaktivität. Der HHR-basierten Assay verwendet eine modifizierte Version der ATPase 6 mRNA, die modelliert wird als ein Ribozym nach Bearbeitung verhalten. Die funktionelle Ribozym dann spaltet spezifisch eine radioaktiv markierte RNA-Substrat, als Reporter dient. Kürzlich Moshiri et al. Entwickelt ein &quot;mischen und zu messen&quot; In-vitro-Reporter-Assay HHR-Basis von RNA-Editing überwachen, wo das radioaktiv markierte RNA-Substrat mit einem Fluoreszenz-Resonanz-Energie-Transfer (FRET) Substrat 19 ersetzt. Die prinzipiellen Vorteile dieses Tests sind: (a) es ist eine schnelle und bequeme Mischen und Messen Assaytyp, die Herstellung von aktiven Ribozym und Substratspaltung gleichzeitig erfolgen im gleichen Röhrchen in geringen Mengen (z. B. 20 ul), (b ) es die Verwendung von radioaktiv markierten Materialien vermeidet, (c) die Empfindlichkeit dass Adurch Fluoreszenz Instrumentierung in einem Mikrotiter-Plattenformat, und (d) ein hohes Signal-Rausch-Verhältnis fforded. Unter Verwendung dieses Tests wurde die Wirkung von bekannten RNA-Editing-Ligase Inhibitoren gegen gereinigtes editosome 19 bestätigt. Dieses Experiment bestätigt der Test für die schnelle Identifizierung von RNA-Editing-Hemmer, in erster Linie gegen ganze editosomes von T. brucei. Fig. 1 ist eine detaillierte Schritt-für-Schritt-Schema des fluoreszenzbasierten In-vitro-RNA-Editing-Assay. Dieses Protokoll kann entweder für die Überwachung der RNA-Editing in vitro oder einfach für das Screening von Substanzbibliotheken von verschiedenen Maßstäben angepasst werden verwendet werden.

<table><tbody><tr><td>SDM-79 Medium</td><td>Gibco by Life Technologies</td><td></td><td></td></tr><tr><td>Fetal Bovine Serum</td><td>Life Technologies</td><td>12483-020</td><td>heat inactivation at 55 &amp;#176;C for 1 hr</td></tr><tr><td>Hemin, minimum 80%</td><td>Sigma</td><td>H5533-10G</td><td></td></tr><tr><td>Penicillin-Streptomycin Sollution</td><td>Fisher Scientific</td><td>MT-30-002-CI</td><td></td></tr><tr><td>Dnase 1 recombinant, Rnase Free&amp;nbsp;</td><td>Roche</td><td>4716728001</td><td></td></tr><tr><td>T7 RiboMax Express Large&amp;nbsp; scale RNA&amp;nbsp; production system</td><td>Promega</td><td>P1320</td><td></td></tr><tr><td>Kimble Kontes Dounce Tissue Grinders&amp;nbsp;&amp;nbsp;</td><td>Fisher Scientific</td><td>K885300-0040&amp;nbsp;&amp;nbsp;</td><td></td></tr><tr><td>Gradient Master, ver 5.25&amp;nbsp;</td><td>Biocomp</td><td>107-201M</td><td></td></tr><tr><td>Ultra Clear Tube, 13.2 ml</td><td>Beckman Coulter</td><td>344059</td><td></td></tr><tr><td>Optima L-100XP&amp;nbsp; Ultracentrifuge&amp;nbsp;</td><td>Beckman Coulter</td><td>392052</td><td></td></tr><tr><td>SW 41 Ti ROTOR</td><td>Beckman Coulter</td><td>331336</td><td></td></tr><tr><td>MicroSeal &#039;B&#039; Seal, Seals</td><td>Biorad</td><td>MSB1001</td><td></td></tr><tr><td>CFX 384 Touch Real-Time PCR Detection System</td><td>Biorad</td><td>185-5484</td><td></td></tr><tr><td>Acryl/Bis solution (19:1), 40% (w/v)</td><td>Bio Basic</td><td>A0006-500ML</td><td></td></tr><tr><td>Urea, Molecular biology grade, 1 kg</td><td>Life Technologies</td><td>AM9902</td><td></td></tr></tbody></table>

rna catalyst as a reporter for screening drugs against rna editing in trypanosomes

Erhebliche Fortschritte bei der Bestimmung des Mechanismus der mitochondrialen RNA-Editing in Trypanosomen gemacht worden. Ebenso hat erhebliche Fortschritte bei der Identifizierung der Komponenten des editosome Komplex, der RNA-Editing katalysieren gemacht worden. Es ist jedoch noch nicht klar, wie diese Proteine ​​zusammen zu arbeiten. Von einem Hochdurchsatz-Screening gegen die editosome erhalten Chemische Verbindungen können blockieren oder beeinträchtigen einen oder mehrere Schritte im Bearbeitungszyklus. Daher wird die Identifizierung von neuen chemischen Verbindungen wertvolle molekulare Sonden zur Zerlegung der editosome Funktion und Anordnung zu erzeugen. In früheren Studien wurden in vitro-Assays unter Verwendung von Bearbeitungsradioaktiv markierten RNA durchgeführt. Diese Assays sind zeitaufwendig, ineffizient und für Hochdurchsatz-Zwecke ungeeignet. Hier eine homogene Fluoreszenz-basierten &quot;zu mischen und zu messen&quot; Hammerhead-Ribozym in-vitro-Reporter-Assay von RNA-Editing zu überwachen, wird vorgestellt. Nur als Folge von RNA-Editingdas Hammerhead-Ribozym ein Fluoreszenz-Resonanz-Energie-Transfer (FRET)-Substrat Oligoribonukleotid Spaltung erfährt. Dies führt wiederum zu einer Trennung des Fluorophors vom Quencher, wodurch ein Signal erzeugt wird. Im Gegensatz dazu, wenn die editosome Funktion gesperrt ist, wird das Fluoreszenzsignal gelöscht werden. Dies ist eine sehr empfindliche und einfache Tests, der allgemein für in vitro-RNA-Editing oder Hochdurchsatz-Screening von Chemikalien, die die editosome Funktion hemmen können überwacht werden sollte.

Um die notwendigen Schritte für den Aufbau einer großen Leinwand zeigen, erforderlich, Fig. 2-5 sind repräsentative Kontrollexperimenten auf die Qualität des Tests zusammen. Dies sind wesentliche Kontrollversuche für eine konsistente Assay über mehrere Tage zum Screenen oder zum Vergleich von verschiedenen Bildschirmen. Die Bewertung der Fluoreszenz-Signal-zu-Rausch-Verhältnis Um die Stabilität und die Qualität der Fluor...

Watch this Scientific Journal Video about RNA Catalyst as a Reporter for Screening Drugs against RNA Editing in Trypanosomes at JoVE.com

RNA Catalyst as a Reporter for Screening Drugs against RNA Editing in Trypanosomes

A highly sensitive ribozyme-based assay, applicable to high-throughput screening of chemicals targeting the unique process of RNA editing in trypanosomatid pathogens, is described in this paper. Inhibitors can be used as tools for hypothesis-driven analysis of the RNA editing process and ultimately as therapeutics.

RNA-Katalysator als Reporter für Drogen-Screening gegen RNA-Editing in Trypanosomen

Substantial progress has been made in determining the mechanism of mitochondrial RNA editing in trypanosomes. Similarly, considerable progress has been ...

rna-catalyst-as-reporter-for-screening-drugs-against-rna-editing

Universidad de Cartagena UDEC

Research

JoVE Journal

Biology

8.4K Aufrufe.  McGill University. A highly sensitive ribozyme-based assay, applicable to high-throughput screening of chemicals targeting the unique process of RNA editing in trypanosomatid pathogens, is described in this paper. Inhibitors can be used as tools for hypothesis-driven analysis of the RNA editing process and ultimately as therapeutics.

Serie: RNA Catalyst as a Reporter for Screening Drugs against RNA Editing in Trypanosomes

Enhanced Genome Editing with Cas9 Ribonucleoprotein in Diverse Cells and Organisms

Site-specific eukaryotic genome editing with CRISPR (clustered regularly interspaced short palindromic repeats)-Cas (CRISPR-associated) systems has quickly become a commonplace amongst researchers pursuing a wide variety of biological questions. Users most often employ the Cas9 protein derived from Streptococcus pyogenes in a complex with an easily reprogrammed guide RNA (gRNA). These components are introduced into cells, and through a base pairing with a complementary region of the double-stranded DNA (dsDNA) genome, the enzyme cleaves both strands to generate a double-strand break (DSB). Subsequent repair leads to either random insertion or deletion events (indels) or the incorporation of experimenter-provided DNA at the site of the break.
The use of a purified single-guide RNA and Cas9 protein, preassembled to form an RNP and delivered directly to cells, is a potent approach for achieving highly efficient gene editing. RNP editing particularly enhances the rate of gene insertion, an outcome that is often challenging to achieve. Compared to the delivery via a plasmid, the shorter persistence of the Cas9 RNP within the cell leads to fewer off-target events. 
Despite its advantages, many casual users of CRISPR gene editing are less familiar with this technique. To lower the barrier to entry, we outline detailed protocols for implementing the RNP strategy in a range of contexts, highlighting its distinct benefits and diverse applications. We cover editing in two types of primary human cells, T cells and hematopoietic stem/progenitor cells (HSPCs). We also show how Cas9 RNP editing enables the facile genetic manipulation of entire organisms, including the classic model roundworm Caenorhabditis elegans and the more recently introduced model crustacean, Parhyale hawaiensis.

Utilizing a preassembled Cas9 ribonucleoprotein complex (RNP) is a powerful method for precise, efficient genome editing. Here, we highlight its utility across a broad range of cells and organisms, including primary human cells and both classic and emerging model organisms.

Verbesserte Genom Bearbeitung mit Cas9 Ribonucleoprotein in verschiedenen Zellen und Organismen

Site-specific eukaryotic genome editing with CRISPR (clustered regularly interspaced short palindromic repeats)-Cas (CRISPR-associated) systems has ...

Forschung

Genetik

Antibody-Free Assay for RNA Methyltransferase Activity Analysis

There are more than 100 chemically distinct modifications of RNA, two thirds of which consist of methylations. Interest in RNA modifications, and especially methylations, has re-emerged due to the important roles played by the enzymes that write and erase them in biological processes relevant to disease and cancer. Here, a sensitive in vitro assay for accurate analysis of RNA methylation writer activity on synthetic or in vitro transcribed RNAs is provided. This assay uses a tritiated form of S-adenosyl-methionine, resulting in direct labeling of methylated RNA with tritium. The low energy of tritium radiation makes the method safe, and pre-existing methods of tritium signal amplification, make it possible to quantify and to visualize the methylated RNA without the use of antibodies, which are commonly prone to artifacts. While this method is written for RNA methylation, few tweaks make it applicable to the study of other RNA modifications that can be radioactively labeled, such as RNA acetylation with 14C acetyl coenzyme A. Overall, this assay allows to quickly assess RNA methylation conditions, inhibition with small molecule inhibitors, or the effect of RNA or enzyme mutants, and provides a powerful tool to validate and expand results obtained in cells.

Here, an antibody-free in vitro assay for direct analysis of methyltransferase activity on synthetic or in vitro transcribed RNA is described.

Antikörperfreier Assay für rna-Methyltransferase-Aktivitätsanalyse

There are more than 100 chemically distinct modifications of RNA, two thirds of which consist of methylations. Interest in RNA modifications, and ...

Optimizing the Genetic Incorporation of Chemical Probes into GPCRs for Photo-crosslinking Mapping and Bioorthogonal Chemistry in Live Mammalian Cells

The genetic incorporation of non-canonical amino acids (ncAAs) via amber stop codon suppression is a powerful technique to install artificial probes and reactive moieties onto proteins directly in the live cell. Each ncAA is incorporated by a dedicated orthogonal suppressor-tRNA/amino-acyl-tRNA-synthetase (AARS) pair that is imported into the host organism. The incorporation efficiency of different ncAAs can greatly differ, and be unsatisfactory in some cases. Orthogonal pairs can be improved by manipulating either the AARS or the tRNA. However, directed evolution of tRNA or AARS using large libraries and dead/alive selection methods are not feasible in mammalian cells. Here, a facile and robust fluorescence-based assay to evaluate the efficiency of orthogonal pairs in mammalian cells is presented. The assay allows screening tens to hundreds of AARS/tRNA variants with a moderate effort and within a reasonable time. Use of this assay to generate new tRNAs that significantly improve the efficiency of the pyrrolysine orthogonal system is described, along with the application of ncAAs to the study of G-protein coupled receptors (GPCRs), which are challenging objects for ncAA mutagenesis. First, by systematically incorporating a photo-crosslinking ncAA throughout the extracellular surface of a receptor, binding sites of different ligands on the intact receptor are mapped directly in the live cell. Second, by incorporating last-generation ncAAs into a GPCR, ultrafast catalyst-free receptor labeling with a fluorescent dye is demonstrated, which exploits bioorthogonal strain-promoted inverse Diels Alder cycloaddition (SPIEDAC) on the live cell. As ncAAs can be generally applied to any protein independently on its size, the method is of general interest for a number of applications. In addition, ncAA incorporation does not require any special equipment and is easily performed in standard biochemistry labs.

A facile fluorescence assay is presented to evaluate the efficiency of amino-acyl-tRNA-synthetase/tRNA pairs incorporating non-canonical amino-acids (ncAAs) into proteins expressed in mammalian cells. The application of ncAAs to study G-protein coupled receptors (GPCRs) is described, including photo-crosslinking mapping of binding sites and bioorthogonal GPCR labeling on live cells.

Optimierung der genetischen Einbeziehung der chemischen Sonden in GPCRs für Foto-Vernetzung-Mapping und Bioorthogonal Chemie in Live Säugerzellen

The genetic incorporation of non-canonical amino acids (ncAAs) via amber stop codon suppression is a powerful technique to install artificial probes and ...

Chemie

CRISPR/Cas9 Editing of the C. elegans rbm-3.2 Gene using the dpy-10 Co-CRISPR Screening Marker and Assembled Ribonucleoprotein Complexes.

The bacterial Clustered Regularly Interspaced Short Palindromic Repeat (CRISPR)/Streptococcus pyogenes CRISPR-associated protein (Cas) system has been harnessed by researchers to study important biologically relevant problems. The unparalleled power of the CRISPR/Cas genome editing method allows researchers to precisely edit any locus of their choosing, thereby facilitating an increased understanding of gene function. Several methods for editing the C. elegans genome by CRISPR/Cas9 have been described previously. Here, we discuss and demonstrate a method which utilizes in vitro assembled ribonucleoprotein complexes and the dpy-10 co-CRISPR marker for screening. Specifically, in this article, we go through the step-by-step process of introducing premature stop codons into the C. elegans rbm-3.2 gene by homology-directed repair using this method of CRISPR/Cas9 editing. This relatively simple editing method can be used to study the function of any gene of interest and allows for the generation of homozygous-edited C. elegans by CRISPR/Cas9 editing&#160;in less than two weeks.

CRISPR/Cas9 Editing of the C. elegans rbm-3.2 Gene using the dpy-10 Co-CRISPR Screening Marker and Assembled Ribonucleoprotein Complexes.

The goal of this protocol is to enable seamless CRISPR/Cas9 editing of the C. elegans genome using assembled ribonucleoprotein complexes and the dpy-10 co-CRISPR marker for screening. This protocol can be used to make a variety of genetic modifications in C. elegans including insertions, deletions, gene replacements and codon substitutions.

CRISPR/Cas9-Editierung des C. elegans rbm-3.2-Gens mit dem dpy-10 Co-CRISPR Screening Marker und Assembled Ribonucleoprotein Complexes.

The bacterial Clustered Regularly Interspaced Short Palindromic Repeat (CRISPR)/Streptococcus pyogenes CRISPR-associated protein (Cas) system has been ...

Nonradioactive Assay to Measure Polynucleotide Phosphorylation of Small Nucleotide Substrates

Polynucleotide kinases (PNKs) are enzymes that catalyze the phosphorylation of the 5&#39; hydroxyl end of DNA and RNA oligonucleotides. The activity of PNKs can be quantified using direct or indirect approaches. Presented here is a direct, in vitro approach to measure PNK activity that relies on a fluorescently-labeled oligonucleotide substrate and polyacrylamide gel electrophoresis. This approach provides resolution of the phosphorylated products while avoiding the use of radiolabeled substrates. The protocol details how to set up the phosphorylation reaction, prepare and run large polyacrylamide gels, and quantify the reaction products. The most technically challenging part of this assay is pouring and running the large polyacrylamide gels; thus, important details to overcome common difficulties are provided. This protocol was optimized for Grc3, a PNK that assembles into an obligate pre-ribosomal RNA processing complex with its binding partner, the Las1 nuclease. However, this protocol can be adapted to measure the activity of other PNK enzymes. Moreover, this assay can also be modified to determine the effects of different components of the reaction, such as the nucleoside triphosphate, metal ions, and oligonucleotides.

This protocol describes a nonradioactive assay to measure kinase activity of polynucleotide kinases (PNKs) on small DNA and RNA substrates.

Nichtradioaktiver Test zur Messung der Polynukleotid-Phosphorylierung kleiner Nukleotidsubstrate

Polynucleotide kinases (PNKs) are enzymes that catalyze the phosphorylation of the 5&#39; hydroxyl end of DNA and RNA oligonucleotides. The activity of ...

Biochemie

NMR-Based Activity Assays for Determining Compound Inhibition, IC50 Values, Artifactual Activity, and Whole-Cell Activity of Nucleoside Ribohydrolases

NMR spectroscopy is often used for the identification and characterization of enzyme inhibitors in drug discovery, particularly in the context of fragment screening. NMR-based activity assays are ideally suited to work at the higher concentrations of test compounds required to detect these weaker inhibitors. The dynamic range and chemical shift dispersion in an NMR experiment can easily resolve resonances from substrate, product, and test compounds. This contrasts with spectrophotometric assays, in which read-out interference problems often arise from compounds with overlapping UV-vis absorption profiles. In addition, since they lack reporter enzymes, the single-enzyme NMR assays are not prone to coupled-assay false positives. This attribute makes them useful as orthogonal assays, complementing traditional high throughput screening assays and benchtop triage assays. Detailed protocols are provided for initial compound assays at 500 &#956;M and 250 &#956;M, dose-response assays for determining IC50 values, detergent counter screen assays, jump-dilution counter screen assays, and assays in E. coli whole cells. The methods are demonstrated using two nucleoside ribohydrolase enzymes. The use of 1H NMR is shown for the purine-specific enzyme, while 19F NMR is shown for the pyrimidine-specific enzyme. The protocols are generally applicable to any enzyme where substrate and product resonances can be observed and distinguished by NMR spectroscopy. To be the most useful in the context of drug discovery, the final concentration of substrate should be no more than 2-3x its Km value. The choice of NMR experiment depends on the enzyme reaction and substrates available as well as available NMR instrumentation.

NMR-Based Activity Assays for Determining Compound Inhibition, IC50 Values, Artifactual Activity, and Whole-Cell Activity of Nucleoside Ribohydrolases

NMR-based activity assays have been developed to identify and characterize inhibitors of two nucleoside ribohydrolase enzymes. Protocols are provided for initial compound assays at 500 &#956;M and 250 &#956;M, dose-response assays for determining IC50 values, detergent counter screen assays, jump-dilution counter screen assays, and assays in E. coli whole cells.

NMR-based Activity Assays for Determining Compound Inhibition, IC50 Values, Artifactual Activity, and Whole-Cell Activity of Nucleoside Ribohydrolases

NMR spectroscopy is often used for the identification and characterization of enzyme inhibitors in drug discovery, particularly in the context of fragment ...

Continuous Fluorescence-Based Endonuclease-Coupled DNA Methylation Assay to Screen for DNA Methyltransferase Inhibitors

DNA methylation, a form of epigenetic gene regulation, is important for normal cellular function. In cells, proteins called DNA methyltransferases (DNMTs) establish and maintain the DNA methylation pattern. Changes to the normal DNA methylation pattern are linked to cancer development and progression, making DNMTs potential cancer drug targets. Thus, identifying and characterizing novel small molecule inhibitors of these enzymes is of great importance. This paper presents a protocol that can be used to screen for DNA methyltransferase inhibitors. The continuous coupled kinetics assay allows for initial velocities of DNA methylation to be determined in the presence and absence of potential small molecule inhibitors. The assay uses the methyl-sensitive endonuclease Gla I to couple methylation of a hemimethylated DNA substrate to fluorescence generation.
This continuous assay allows for enzyme activity to be monitored in real time. Conducting the assay in small volumes in microtiter plates reduces the cost of reagents. Using this assay, a small example screen was conducted for inhibitors of DNMT1, the most abundant DNMT isozyme in humans. The highly substituted anthraquinone natural product, laccaic acid A, is a potent, DNA-competitive inhibitor of DNMT1. Here, we examine three potential small molecule inhibitors &#8212; anthraquinones or anthraquinone-like molecules with one to three substituents &#8212; at two concentrations to describe the assay protocol. Initial velocities are used to calculate the percent activity observed in the presence of each molecule. One of three compounds examined exhibits concentration-dependent inhibition of DNMT1 activity, indicating that it is a potential inhibitor of DNMT1.

DNA methyltransferases are potential cancer drug targets. Here, a protocol is presented to assess small molecules for DNA methyltransferase inhibition. This assay utilizes an endonuclease to couple DNA methylation to fluorescence generation and allows for enzyme activity to be monitored in real time.&#160;

Kontinuierlicher fluoreszenzbasierter Endonuklease-gekoppelter DNA-Methylierungsassay zum Screening auf DNA-Methyltransferase-Inhibitoren

DNA methylation, a form of epigenetic gene regulation, is important for normal cellular function. In cells, proteins called DNA methyltransferases (DNMTs) ...

Measurement of Specific Mycobacterial Mistranslation Rates with Gain-of-function Reporter Systems

The translation of genes into proteins is prone to errors. Although the average rate of translational error in model systems is estimated to be 1/10,000 per codon, the actual error rates vary widely, depending on the species, environment, and codons being studied. We have previously shown that mycobacteria use a two-step pathway for the generation of aminoacylated glutamine and asparagine tRNAs and that this is specifically associated with relatively high error rates due to the modulation of mistranslation rates by an essential component of the pathway, the amidotransferase GatCAB. We modified a previously employed Renilla-Firefly dual-luciferase system that had been used to measure mistranslation rates in Escherichia coli for use in mycobacteria to measure specific mistranslation rates of glutamate at glutamine codons and aspartate for asparagine codons. Although this reporter system was suitable for the accurate estimation of specific error rates, lack of sensitivity and requirements for excessive manipulation steps made it unsuitable for high-throughput applications. Therefore, we developed a second gain-of-function reporter system, using Nluc luciferase and green fluorescent protein (GFP), which is more amenable to medium/high-throughput settings. We used this system to identify kasugamycin as a small molecule that can decrease mycobacterial mistranslation. Although the reporters that we describe here have been used to measure specific types of mycobacterial mistranslation, they may be modified to measure other types of mistranslation in a number of model systems.

In this article, we present two complementary methods to measure specific rates of translational error and mistranslation in the model mycobacterium, Mycobacterium smegmatis, using gain-of-function reporter systems. The methods can be employed to measure accurate error rates in low throughput or relative error rates in a more high-throughput setting.

Messung spezieller mycobakterieller Mistranslation-Raten mit Funktionsfunktionen

The translation of genes into proteins is prone to errors. Although the average rate of translational error in model systems is estimated to be 1/10,000 ...

Immunologie und Infektion

A Nonsequencing Approach for the Rapid Detection of RNA Editing

RNA editing is a process that leads to posttranscriptional sequence alterations in RNAs. Detection and quantification of RNA editing rely mainly on Sanger sequencing and RNA sequencing techniques. However, these methods can be costly and time-consuming. In this protocol, a portable microtemperature gradient gel electrophoresis (&#181;TGGE) system is used as a nonsequencing approach for the rapid detection of RNA editing. The process is based on the principle of electrophoresis, which uses high temperatures to denature nucleic acid samples as they move across a polyacrylamide gel. Across a range of temperatures, a DNA fragment forms a gradient of fully double-stranded DNA to partially separated strands and then to entirely separated single-stranded DNA. RNA-edited sites with distinct nucleotide bases produce different melting profiles in &#181;TGGE analyses. We used the &#181;TGGE-based approach to characterize the differences between the melting profiles of four edited RNA fragments and their corresponding nonedited (wild-type) fragments. Pattern Similarity Scores (PaSSs) were calculated by comparing the band patterns produced by the edited and nonedited RNAs and were used to assess the reproducibility of the method. Overall, the platform described here enables the detection of even single base mutations in RNAs in a straightforward, simple, and cost-effective manner. It is anticipated that this analysis tool will aid new molecular biology findings.

Rapid detection and reliable quantification of RNA editing events at a genomic scale remain challenging and currently rely on direct RNA sequencing methods. The protocol described here uses microtemperature gradient gel electrophoresis (&#181;TGGE) as a simple, quick, and portable method of detecting RNA editing.

Ein Nonsequencing-Ansatz für den schnellen Nachweis der RNA-Editierung

RNA editing is a process that leads to posttranscriptional sequence alterations in RNAs. Detection and quantification of RNA editing rely mainly on Sanger ...

Biotechnik

High-throughput Screening for Chemical Modulators of Post-transcriptionally Regulated Genes

Both transcriptional and post-transcriptional regulation have a profound impact on genes expression. However, commonly adopted cell-based screening assays focus on transcriptional regulation, being essentially aimed at the identification of promoter-targeting molecules. As a result, post-transcriptional mechanisms are largely uncovered by gene expression targeted drug development. Here we describe a cell-based assay aimed at investigating the role of the 3&#39; untranslated region (3&#8217; UTR) in the modulation of the fate of its mRNA, and at identifying compounds able to modify it. The assay is based on the use of a luciferase reporter construct containing the 3&#8217; UTR of a gene of interest stably integrated into a disease-relevant cell line. The protocol is divided into two parts, with the initial focus on the primary screening aimed at the identification of molecules affecting luciferase activity after 24 hr of treatment. The second part of the protocol describes the counter-screening necessary to discriminate compounds modulating luciferase activity specifically through the 3&#8217; UTR. In addition to the detailed protocol and representative results, we provide important considerations about the assay development and the validation of the hit(s) on the endogenous target. The described cell-based reporter gene assay will allow scientists to identify molecules modulating protein levels via post-transcriptional mechanisms dependent on a 3&#8217; UTR.

Here we describe a cell-based reporter gene assay as a valuable tool to screen chemical libraries for compounds modulating post-transcriptional control mechanisms exerted through 3&#8217; UTR.

Hochdurchsatz-Screening für Chemische Modulatoren der Post-transkriptionell regulierten Genen

Both transcriptional and post-transcriptional regulation have a profound impact on genes expression. However, commonly adopted cell-based screening assays ...