Diese Arbeit wurde durch ein FAPESP-Stipendium (15/06477-9) unterstützt.

1. Zubereitung von Hefe-Gesamtextrakt
<ol><li>Wachsen sie die Hefezellen, die einen der mit dem TAP-Tag9 verschmolzenen Spleißfaktoren in 1 L YNB-Glu-Medien (Hefestickstoffbasis ergänzt mit 2% m/v Glucose) mit den entsprechenden Aminosäuren oder Nukleinbasen, in diesem Fall Adenin (20 μg/ml), Leucin (30 μg/ml), Tryptophan (30 μg/ml), bis zu OD600 = 1,0, exprimieren.</li>
	<li>Die Zellen aus der 1 L-Kultur durch Zentrifugieren in drei 500-ml-Zentrifugenflaschen bei 17.000 x g für 10 min bei 4 °C sammeln und zweimal mit 10 ml kaltem sterilem Wasser waschen.</li>
	<li>Resuspendieren Sie die gesammelten Hefezellen in 1/10 des Zellvolumens des Kaltpuffers A (10 mmolL-1 HEPES pH = 7,9, 1,5 mmolL-1 MgCl2, 50 mmolL-1 KCl, 5% v/v Glycerin, 0,5 mmolL-1 DTT, EDTA-freier Protease-Inhibitor-Cocktail).</li>
	<li>Kleine Tropfen Zellsuspension in flüssigem Stickstoff einfrieren. Die kleinen Tropfen können erhalten werden, indem die resuspendierte Zelllösung pipetiert und 50 μL direkt in flüssigen Stickstoff fallen gelassen werden. ACHTUNG: Flüssiger Stickstoff kann bei Kontakt mit Haut oder Augen zu Verletzungen führen. Handhabung mit geeigneter Sicherheitsausrüstung. HINWEIS: Das Protokoll kann hier pausiert werden. Die gefrorenen Tropfen der Zellsuspension können bei -80 °C gelagert werden.</li>
	<li>Bereiten Sie Hefezellen Lysate vor, indem Sie in einem Kugelmühlengerät durch sechs Zyklen bei 20 Hz / s für 3 min mahlen. HINWEIS: Tauchen Sie nach jedem Zyklus den Behälter, in dem sich die gefrorenen Zellen befinden, in flüssigen Stickstoff, um ein Schmelzen zu vermeiden. Das Protokoll kann hier pausiert werden. Die gefrorenen Extrakte können bei -80 °C gelagert werden. Hefe-Spleißextrakte können auch mit Homogenisatoren hergestellt werden, um Spheroplasten10zu lysatieren, oder mit Mörser und Stößel11,12.</li>
	<li>Schmelzen Sie den Extrakt, indem Sie die Röhrchen, die sie enthalten, bei Raumtemperatur in Wasser legen und gelegentlich schütteln.</li>
	<li>Zentrifugenextrakte bei 45.000 x g für 1 h bei 4 °C.</li>
	<li>Quantifizierung des Proteingehalts des geklärten Überstandes mit der BCA-Methode13.</li>
	<li>Aliquoten der Extrakte vorbereiten, schnell in flüssigem Stickstoff einfrieren und bei -80 °C lagern. HINWEIS: Das Protokoll kann hier pausiert werden.</li>
</ol>2. Glyceringradientenvorbereitung
<ol><li>Bereiten Sie zwei Glycerinlösungen in Puffer A vor, eine mit 10% v / v und die andere mit 30% v / v Glycerin.</li>
	<li>Das Vernetzungsmittel Glutaraldehyd zu 0,1% v/v in die 30%ige v/v Glycerinlösung geben und homogenisieren. ACHTUNG: Behandeln Sie Glutaraldehyd im Abzug mit geeigneten Sicherheitsvorrichtungen.</li>
	<li>6 mL der kalten 10% v/v Glycerinlösung am Boden des 12 mL Zentrifugenröhrchens (14 x 89 mm) hinzufügen.</li>
	<li>Fügen Sie 6 ml der kalten 30% v / v Glycerinlösung, ergänzt mit Glutaraldehyd, mit einer Spritze hinzu, die an einer langen Nadel befestigt ist, die mit dem Gradient Master-Gerät am Boden des Röhrchens geliefert wird, direkt unter der 10% v / v Glycerinlösung. HINWEIS: Alternativ kann die 10% v/v Glycerinlösung vorsichtig auf die Oberseite der 30%igen v/v Glycerin/Glutaraldehyd-Lösung pipettiert werden.</li>
	<li>Verwenden Sie das Gradient Master-Gerät, um einen kontinuierlichen Dichtegradienten zu generieren. HINWEIS: Im Gradient Master-Gerät werden die Rohre in ein geeignetes Rack gelegt und kurz gedreht, wobei die Empfehlungen des Herstellers zur Bestimmung der Parameter (Zeit/Winkel/Geschwindigkeit) befolgt werden. In dieser Arbeit verwendeten wir: 2:25 min/81,5°/11 rpm.</li>
	<li>Fügen Sie vorsichtig 200 μL eines 7% v / v Glycerin / Puffer-A-Kissens auf der Oberseite kurz vor der Zugabe der Zellextrakte hinzu. HINWEIS: Die Glycerinkonzentration des Kissens muss niedriger sein als die weniger konzentrierte Glycerinlösung, die zur Erstellung des linearen Gradienten verwendet wird.</li>
</ol>3. Extrahiert zentrifugation
<ol><li>Laden Sie ca. 2 mg Gesamtprotein auf die Oberseite jedes 12 ml linearen Glyceringradienten 10% bis 30% Glutaraldehyd mit Kissen.</li>
	<li>Legen Sie die Rohre in einen vorgekühlten Schaufelrotor. HINWEIS: Behandeln Sie die Röhrchen vorsichtig, um eine Vermischung vor der Ultrazentrifugation zu vermeiden.</li>
	<li>Zentrifuge bei 194.000 x g für 16 h bei 4 °C.</li>
	<li>Aliquot jedes 12 mL Röhrchen in vierundzwanzig 500 μL Fraktionen mit einem angepassten EconoSystem oder durch sorgfältiges Pipettieren. HINWEIS: Ein angepasstes EconoSystem besteht aus einer Peristaltikpumpe, dem UV-Detektor und dem Fraktionskollektor, der mit der Rohrperforationsvorrichtung verbunden ist. Das Sedimentationsprofil kann durch die Messung der Absorption bei 280 nm überwacht werden.</li>
	<li>Verwenden Sie eine 40% v/ v Glycerinlösung durch die Peristaltikpumpe, um den Glyceringradienten von 10% bis 30% vom Rohr zum Fraktionskollektor zu drücken. HINWEIS: Das Protokoll kann hier pausiert werden. Lagern Sie die Fraktionen bei -80 °C bis zum Gebrauch.</li>
	<li>Laden Sie 50 μL jeder Fraktion direkt auf Nitrocellulosemembranen auf einem Dot-Blot- oder Slot-Blot-Gerät. Nachweis von Protein durch Immunoblot mit Antikörpern gegen CBP (1:6.000, um den CBP-Teil des TAP-Tags nachzuweisen) und Anti-Kaninchen-IgG, konjugiert mit Meerrettichperoxidase (1:15.000) als sekundärer Antikörper.</li>
</ol>

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D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Structure,+function+and+regulation+of+spliceosomal+RNA+helicases.">Structure, function and regulation of spliceosomal RNA helicases.</a> Current Opinion in Cell Biology. 24, 431-438 (2012).</li><li>Kastner, B., 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=GraFix:+sample+preparation+for+single-particle+electron+cryomicroscopy.">GraFix: sample preparation for single-particle electron cryomicroscopy.</a> Nature Methods. 5 (1), 53-55 (2008).</li><li>Stark, H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Grafix:+stabilization+of+fragile+macromolecular+complexes+for+single+particle+cryo-EM.">Grafix: stabilization of fragile macromolecular complexes for single particle cryo-EM.</a> Methods in Enzymology. 481, 109-126 (2010).</li><li>Yan, C., Wan, R., Bai, R., Huang, G., Shi, Y. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Structure+of+a+yeast+activated+spliceosome+at+3.5+&#197;+resolution.">Structure of a yeast activated spliceosome at 3.5 &#197; resolution.</a> Science. 353 (6302), 895-904 (2016).</li><li>Ohi, M. D., 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=Proteomics+analysis+revelas+stable+multiprotein+complexes+in+both+fission+and+budding+yeasts+containing+Myb-related+Cdc5p/Cef1p,+novel+pre-mRNA+splicing+factors,+and+snRNAs.">Proteomics analysis revelas stable multiprotein complexes in both fission and budding yeasts containing Myb-related Cdc5p/Cef1p, novel pre-mRNA splicing factors, and snRNAs.</a> Molecular and Cellular Biology. 22 (7), 2011-2024 (2002).</li><li>Lourenco, R. F., Leme, A. F. P., Oliveira, C. C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Proteomic+analysis+of+yeast+mutant+RNA+exosome+complexes.">Proteomic analysis of yeast mutant RNA exosome complexes.</a> Journal of Proteome Research. 12 (12), 5912-5922 (2013).</li><li>Rigaut, G., 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=A+generic+protein+purification+method+for+protein+complex+characterizatioin+and+proteome+exploration.">A generic protein purification method for protein complex characterizatioin and proteome exploration.</a> Nature Biotechnology. 17, 1030-1032 (1999).</li><li>Cheng, S. C., Newman, A., Lin, R. J., McFarland, G. D., Abelson, J. 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Die Autoren haben keine Interessenkonflikte.

Protein-Protein- und Ribonukleinsäure-Protein-Interaktionen können mit Vernetzern stabilisiert werden. Es ist wichtig, dass der resultierende Komplex stabil ist, um einer Ultrazentrifugation auf Glyceringradient standzuhalten. Darüber hinaus sollten die Pufferbedingungen die Interaktion ermöglichen, aber streng genug sein, um eine unspezifische Bindung zu vermeiden. In den hier gezeigten Experimenten haben wir eine bereits etablierte Pufferlösung für In-vitro-Spleißreaktionenverwendet 15.</...

Spleißen ist ein hochdynamischer Prozess, der eine Vielzahl von Faktoren koordiniert binden und freisetzen muss. Zu diesen Spleißfaktoren gehören RNA-bindende Proteine, ATPasen, Helikasen, Proteinkinasen und Phosphatasen, Ubiquitinligasen, unter anderem1,2,3; und um die molekularen Umlagerungen zu ermöglichen, binden einige dieser Faktoren sehr vorübergehend an die Spleißosom-Subkomplexe, was die Isolierung und Identifizierung dieser RNP-Zwischenkomplexe sehr schwierig macht.
Hier haben wir die Grafix-Methode4,5 verwendet, um die Wechselwirkung des Hefe-Spleißfaktors Cwc24 mit demB-Act-Komplex 6 zu stabilisieren, um die Identifizierung anderer Faktoren zu ermöglichen, die gleichzeitig an diesen Subkomplex gebunden sind, und um festzustellen, ob die Ubiquitinligase Prp19 eine Rolle bei der Bindung oder Freisetzung von Cwc24 an den Nineteen (NTC) -Komplex und an das 5'-Ende des Introns vor der Aktivierung spielt und die erste Transesterreaktion dauert Ort. Der Vorteil der Exposition der Makromoleküle gegenüber einer zunehmenden Konzentration des Vernetzers entlang des Glyceringradienten besteht darin, dass es Interkomplexvernetzungen4,5und damit die Bildung von Aggregaten vermeidet.
Diese Methode wurde als Ergänzung zu Protein-Coimmunopräzipitations- und Pull-Down-Assays verwendet, die, obwohl sie die Isolierung großer Komplexe ermöglichen, möglicherweise nicht zuverlässig sind, um transiente Wechselwirkungen innerhalb großer dynamischer Komplexeaufrechtzuerhalten 7,8. Die Verwendung von Fixierungsreagenzien im Glyceringradienten stabilisiert die Bindung solcher Faktoren und ermöglicht die Bestätigung der Wechselwirkungen spezifischer Proteine mit Spleißsubkomplexen. Da der gewählte Vernetzer chemisch irreversibel war, wurden die in den wiederhergestellten Fraktionen vorhandenen Proteine nach der Gradientenzentrifugation per Punktblot analysiert.

<table>
	<tbody>
		<tr>
			<td>Anti-Calmodulin Binding Protein Epitope</td>
			<td>Millipore</td>
			<td>07-482</td>
			<td></td>
		</tr>
		<tr>
			<td>ECL anti-Rabbit IgG</td>
			<td>GE Healthcare</td>
			<td>NA934</td>
			<td></td>
		</tr>
		<tr>
			<td>EconoSystem</td>
			<td>Bio-Rad</td>
			<td>1-800-424-6723</td>
			<td>Parts of the EconoSystem used: peristaltic pump, the UV detector and the fraction collector</td>
		</tr>
		<tr>
			<td>EDTA-free Protease Inhibitor Cocktail</td>
			<td>Roche</td>
			<td>11873580001</td>
			<td></td>
		</tr>
		<tr>
			<td>Fraction Recovery System</td>
			<td>Beckman Coulter</td>
			<td>270-331580</td>
			<td>Tube-perforating device that was connected to the parts of the EconoSystem</td>
		</tr>
		<tr>
			<td>Gradient Master Model 107ip</td>
			<td>Biocomp</td>
			<td>107-201M</td>
			<td></td>
		</tr>
		<tr>
			<td>Mixer Mill MM 200</td>
			<td>Retsch</td>
			<td>207460001</td>
			<td>Ball Mill device</td>
		</tr>
		<tr>
			<td>Rotor F12-6x500Lex</td>
			<td>Thermo Scientific</td>
			<td>096-062375</td>
			<td></td>
		</tr>
		<tr>
			<td>Sorvall RC 6 Plus Centrifuge</td>
			<td>Thermo Scientific</td>
			<td>36-101-0816</td>
			<td></td>
		</tr>
		<tr>
			<td>Swinging Bucket Rotor P40ST</td>
			<td>Hitachi</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Ultracentrifuge CP 80 NX</td>
			<td>Hitachi</td>
			<td>901069</td>
			<td></td>
		</tr>
		<tr>
			<td>Ultra-Clear Centrifuge Tubes (14 x 89 mm)</td>
			<td>Beckman Coulter</td>
			<td>344059</td>
			<td></td>
		</tr>
	</tbody>
</table>

utilization of grafix for the detection of transient interactors of saccharomyces cerevisiae spliceosome subcomplexes

Pre-mRNA-Spleißen ist ein sehr dynamischer Prozess, der viele molekulare Umlagerungen der Spleißosom-Subkomplexe während der Montage, RNA-Verarbeitung und Freisetzung der komplexen Komponenten beinhaltet. Die Glyceringradientenzentrifugation wurde zur Trennung von Protein- oder RNP-Komplexen (RiboNucleoProtein) für funktionelle und strukturelle Studien verwendet. Hier beschreiben wir die Verwendung von Grafix (Gradient Fixation), das zuerst entwickelt wurde, um makromolekulare Komplexe für die Einzelpartikel-Kryo-Elektronenmikroskopie zu reinigen und zu stabilisieren, um Wechselwirkungen zwischen Spleißfaktoren zu identifizieren, die vorübergehend an den Spleißosomenkomplex binden. Diese Methode basiert auf der Zentrifugation von Proben in eine zunehmende Konzentration eines Fixierungsreagenz zur Stabilisierung von Komplexen. Nach der Zentrifugation von Hefe-Gesamtextrakten, die auf Glyceringradienten geladen sind, werden die wiedergewonnenen Fraktionen durch Dot-Blot analysiert, um die Spleißosom-Subkomplexe zu identifizieren und das Vorhandensein einzelner Spleißfaktoren zu bestimmungen.

Um das Sedimentationsprofil von Cwc24-TAP zu analysieren und festzustellen, ob die Grafix-Methode wirksam war, um seine Bindung an Spleißsubkomplexe zu stabilisieren, trennten wir Gesamthefeextrakte von Zellen, die Cwc24-TAP durch Zentrifugation auf Glyceringradienten exprimieren, in Gegenwart oder Abwesenheit von Glutaraldehyd als Vernetzungsmittel. Proben von vierundzwanzig 500 μL-Fraktionen wurden dann durch Slot-Blot mit Antikörpern gegen den CBP-Teil des TAP-Tags analysiert. Die Ergebnisse zeigen, dass Cwc24 in A...

Watch this Scientific Journal Video about Utilization of Grafix for the Detection of Transient Interactors of Saccharomyces cerevisiae Spliceosome Subcomplexes at JoVE.com

Utilization of Grafix for the Detection of Transient Interactors of Saccharomyces cerevisiae Spliceosome Subcomplexes

Hier beschreiben wir die Verwendung von Grafix (Gradient Fixation), einer Glyceringradientenzentrifugation in Gegenwart eines Vernetzers, um Wechselwirkungen zwischen Spleißfaktoren zu identifizieren, die vorübergehend an den Spleißosomkomplex binden.

Verwendung von Grafix zum Nachweis transienter Interaktoren von Saccharomyces cerevisiae Spliceosome Subcomplexes

Pre-mRNA splicing is a very dynamic process that involves many molecular rearrangements of the spliceosome subcomplexes during assembly, RNA processing, ...

utilization-grafix-for-detection-transient-interactors-saccharomyces

Research

JoVE Journal

Biochemistry

Utilization of Grafix for the Detection of Transient Interactors of Saccharomyces cerevisiae Spliceosome Subcomplexes

3.5K Aufrufe.  University of Sao Paulo. Hier beschreiben wir die Verwendung von Grafix (Gradient Fixation), einer Glyceringradientenzentrifugation in Gegenwart eines Vernetzers, um Wechselwirkungen zwischen Spleißfaktoren zu identifizieren, die vorübergehend an den Spleißosomkomplex binden.

Serie: Utilization of Grafix for the Detection of Transient Interactors of Saccharomyces cerevisiae Spliceosome Subcomplexes

Studying RNA Interactors of Protein Kinase RNA-Activated during the Mammalian Cell Cycle

Protein kinase RNA-activated (PKR) is a member of the innate immune response proteins and recognizes the double-stranded secondary structure of viral RNAs. When bound to viral double-stranded RNAs (dsRNAs), PKR undergoes dimerization and subsequent autophosphorylation. Phosphorylated PKR (pPKR) becomes active and induces phosphorylation of the alpha subunit of eukaryotic initiation factor 2 (eIF2&#945;) to suppress global translation. Increasing evidence suggests that PKR can be activated under physiological conditions such as during the cell cycle or under various stress conditions without infection. However, our understanding of the RNA activators of PKR is limited due to the lack of a standardized experimental method to capture and analyze PKR-interacting dsRNAs. Here, we present an experimental protocol to specifically enrich and analyze PKR bound RNAs during the cell cycle using HeLa cells. We utilize the efficient crosslinking activity of formaldehyde to fix PKR-RNA complexes and isolate them via immunoprecipitation. PKR co-immunoprecipitated RNAs can then be further processed to generate a high-throughput sequencing library. One major class of PKR-interacting cellular dsRNAs is mitochondrial RNAs (mtRNAs), which can exist as intermolecular dsRNAs through complementary interaction between the heavy-strand and the light-strand RNAs. To study the strandedness of these duplex mtRNAs, we also present a protocol for strand-specific qRT-PCR. Our protocol is optimized for the analysis of PKR-bound RNAs, but it can be easily modified to study cellular dsRNAs or RNA-interactors of other dsRNA binding proteins.

We present experimental approaches for studying RNA-interactors of double-stranded RNA binding protein kinase RNA-activated (PKR) during the mammalian cell cycle using HeLa cells. This method utilizes formaldehyde to crosslink RNA-PKR complexes and immunoprecipitation to enrich PKR-bound RNAs. These RNAs can be further analyzed through high-throughput sequencing or qRT-PCR.

Studium der RNA Interaktoren des RNA während der Säugetier-Zelle Zyklus aktiviert Proteinkinase

Protein kinase RNA-activated (PKR) is a member of the innate immune response proteins and recognizes the double-stranded secondary structure of viral ...

Forschung

Biochemie

Study on the Metabolism of Six Systemic Insecticides in a Newly Established Cell Suspension Culture Derived from Tea (Camellia Sinensis L.) Leaves

A platform for studying insecticide metabolism using in vitro tissues of tea plant was developed. Leaves from sterile tea plantlets were induced to form loose callus on Murashige and Skoog (MS) basal media with the plant hormones 2,4-dichlorophenoxyacetic acid (2,4-D, 1.0 mg L-1) and kinetin (KT, 0.1 mg L-1). Callus formed after 3 or 4 rounds of subculturing, each lasting 28 days. Loose callus (about 3 g) was then inoculated into B5 liquid media containing the same plant hormones and was cultured in a shaking incubator (120 rpm) in the dark at 25 &#177; 1 &#176;C. After 3&#8722;4 subcultures, a cell suspension derived from tea leaf was established at a subculture ratio ranging between 1:1 and 1:2 (suspension mother liquid: fresh medium). Using this platform, six insecticides (5 &#181;g mL-1 each thiamethoxam, imidacloprid, acetamiprid, imidaclothiz, dimethoate, and omethoate) were added into the tea leaf-derived cell suspension culture. The metabolism of the insecticides was tracked using liquid chromatography and gas chromatography. To validate the usefulness of the tea cell suspension culture, the metabolites of thiamethoxan and dimethoate present in treated cell cultures and intact plants were compared using mass spectrometry. In treated tea cell cultures, seven metabolites of thiamethoxan and two metabolites of dimethoate were found, while in treated intact plants, only two metabolites of thiamethoxam and one of dimethoate were found. The use of a cell suspension simplified the metabolic analysis compared to the use of intact tea plants, especially for a difficult matrix such as tea.

Study on the Metabolism of Six Systemic Insecticides in a Newly Established Cell Suspension Culture Derived from Tea Camellia Sinensis L. Leaves

This work presents a protocol for establishing a cell suspension culture derived from tea (Camellia sinensis L.) leaves that can be used to study the metabolism of external compounds that can be taken up by the whole plant, such as insecticides.

Studie über den Stoffwechsel von sechs systemischen Insektiziden in einer neu etablierten Zellsuspensionskultur abgeleitet aus Tee (Camellia Sinensis L.) Blätter

A platform for studying insecticide metabolism using in vitro tissues of tea plant was developed. Leaves from sterile tea plantlets were induced to form ...

Quantitative Analysis of the Cellular Lipidome of Saccharomyces Cerevisiae Using Liquid Chromatography Coupled with Tandem Mass Spectrometry

Lipids are structurally diverse amphipathic molecules that are insoluble in water. Lipids are essential contributors to the organization and function of biological membranes, energy storage and production, cellular signaling, vesicular transport of proteins, organelle biogenesis, and regulated cell death. Because the budding yeast Saccharomyces cerevisiae is a unicellular eukaryote amenable to thorough molecular analyses, its use as a model organism helped uncover mechanisms linking lipid metabolism and intracellular transport to complex biological processes within eukaryotic cells. The availability of a versatile analytical method for the robust, sensitive, and accurate quantitative assessment of major classes of lipids within a yeast cell is crucial for getting deep insights into these mechanisms. Here we present a protocol to use liquid chromatography coupled with tandem mass spectrometry (LC-MS/MS) for the quantitative analysis of major cellular lipids of S. cerevisiae. The LC-MS/MS method described is versatile and robust. It enables the identification and quantification of numerous species (including different isobaric or isomeric forms) within each of the 10 lipid classes. This method is sensitive and allows identification and quantitation of some lipid species at concentrations as low as 0.2 pmol/&#181;L. The method has been successfully applied to assessing lipidomes of whole yeast cells and their purified organelles. The use of alternative mobile phase additives for electrospray ionization mass spectrometry in this method can increase the efficiency of ionization for some lipid species and can be therefore used to improve their identification and quantitation.

Quantitative Analysis of the Cellular Lipidome of Saccharomyces Cerevisiae Using Liquid Chromatography Coupled with Tandem Mass Spectrometry

We present a protocol using liquid chromatography coupled with tandem mass spectrometry to identify and quantify major cellular lipids in Saccharomyces cerevisiae. The described method for a quantitative assessment of major lipid classes within a yeast cell is versatile, robust, and sensitive.

Quantitative Analyse des Zelllipidoms von Saccharomyces Cerevisiae mit Flüssigchromatographie gekoppelt mit Tandem-Massenspektrometrie

Lipids are structurally diverse amphipathic molecules that are insoluble in water. Lipids are essential contributors to the organization and function of ...

Labelling and Visualization of Mitochondrial Genome Expression Products in Baker's Yeast Saccharomyces cerevisiae

Mitochondria are essential organelles of eukaryotic cells capable of aerobic respiration. They contain circular genome and gene expression apparatus. A mitochondrial genome of baker&#8217;s yeast encodes eight proteins: three subunits of the cytochrome c oxidase (Cox1p, Cox2p, and Cox3p), three subunits of the ATP synthase (Atp6p, Atp8p, and Atp9p), a subunit of the ubiquinol-cytochrome c oxidoreductase enzyme, cytochrome b (Cytb), and mitochondrial ribosomal protein Var1p. The purpose of the method described here is to specifically label these proteins with 35S methionine, separate them by electrophoresis and visualize the signals as discrete bands on the screen. The procedure involves several steps. First, yeast cells are cultured in a galactose-containing medium until they reach the late logarithmic growth stage. Next, cycloheximide treatment blocks cytoplasmic translation and allows 35S methionine incorporation only in mitochondrial translation products. Then, all proteins are extracted from yeast cells and separated by polyacrylamide gel electrophoresis. Finally, the gel is dried and incubated with the storage phosphor screen. The screen is scanned on a phosphorimager revealing the bands. The method can be applied to compare the biosynthesis rate of a single polypeptide in the mitochondria of a mutant yeast strain versus the wild type, which is useful for studying mitochondrial gene expression defects. This protocol gives valuable information about the translation rate of all yeast mitochondrial mRNAs. However, it requires several controls and additional experiments to make proper conclusions.

Labelling and Visualization of Mitochondrial Genome Expression Products in Baker's Yeast Saccharomyces cerevisiae

Baker&#8217;s yeast mitochondrial genome encodes eight polypeptides. The goal of the current protocol is to label all of them and subsequently visualize them as separate bands.

Kennzeichnung und Visualisierung von mitochondrialen Genomexpressionsprodukten in Baker es Yeast Saccharomyces cerevisiae

Mitochondria are essential organelles of eukaryotic cells capable of aerobic respiration. They contain circular genome and gene expression apparatus. A ...

Quantitative Metabolomics of Saccharomyces Cerevisiae Using Liquid Chromatography Coupled with Tandem Mass Spectrometry

Metabolomics is a methodology used for the identification and quantification of many low-molecular-weight intermediates and products of metabolism within a cell, tissue, organ, biological fluid, or organism. Metabolomics traditionally focuses on water-soluble metabolites. The water-soluble metabolome is the final product of a complex cellular network that integrates various genomic, epigenomic, transcriptomic, proteomic, and environmental factors. Hence, the metabolomic analysis directly assesses the outcome of the action for all these factors in a plethora of biological processes within various organisms. One of these organisms is the budding yeast Saccharomyces cerevisiae, a unicellular eukaryote with the fully sequenced genome. Because S. cerevisiae is amenable to comprehensive molecular analyses, it is used as a model for dissecting mechanisms underlying many biological processes within the eukaryotic cell. A versatile analytical method for the robust, sensitive, and accurate quantitative assessment of the water-soluble metabolome would provide the essential methodology for dissecting these mechanisms. Here we present a protocol for the optimized conditions of metabolic activity quenching in and water-soluble metabolite extraction from S. cerevisiae cells. The protocol also describes the use of liquid chromatography coupled with tandem mass spectrometry (LC-MS/MS) for the quantitative analysis of the extracted water-soluble metabolites. The LC-MS/MS method of non-targeted metabolomics described here is versatile and robust. It enables the identification and quantification of more than 370 water-soluble metabolites with diverse structural, physical, and chemical properties, including different structural isomers and stereoisomeric forms of these metabolites. These metabolites include various energy carrier molecules, nucleotides, amino acids, monosaccharides, intermediates of glycolysis, and tricarboxylic cycle intermediates. The LC-MS/MS method of non-targeted metabolomics is sensitive and allows the identification and quantitation of some water-soluble metabolites at concentrations as low as 0.05 pmol/&#181;L. The method has been successfully used for assessing water-soluble metabolomes of wild-type and mutant yeast cells cultured under different conditions.

Quantitative Metabolomics of Saccharomyces Cerevisiae Using Liquid Chromatography Coupled with Tandem Mass Spectrometry

We present a protocol for the identification and quantitation of major classes of water-soluble metabolites in the yeast Saccharomyces cerevisiae. The described method is versatile, robust, and sensitive. It allows the separation of structural isomers and stereoisomeric forms of water-soluble metabolites from each other.

Quantitative Metabolomik von Saccharomyces Cerevisiae mittels Flüssigkeitschromatographie gekoppelt mit Tandem-Massenspektrometrie

Metabolomics is a methodology used for the identification and quantification of many low-molecular-weight intermediates and products of metabolism within ...

Analysis of Neutral Lipid Synthesis in Saccharomyces cerevisiae by Metabolic Labeling and Thin Layer Chromatography

Neutral lipids (NLs) are a class of hydrophobic, chargeless biomolecules that play key roles in energy and lipid homeostasis. NLs are synthesized de novo&#160;from acetyl-CoA and are primarily present in eukaryotes in the form of triglycerides (TGs) and sterol-esters (SEs). The enzymes responsible for the synthesis of NLs are highly conserved from Saccharomyces cerevisiae (yeast) to humans, making yeast a useful model organism to dissect the function and regulation of NL metabolism enzymes. While much is known about how acetyl-CoA is converted into a diverse set of NL species, mechanisms for regulating NL metabolism enzymes, and how mis-regulation can contribute to cellular pathologies, are still being discovered. Numerous methods for the isolation and characterization of NL species have been developed and used over decades of research; however, a quantitative and simple protocol for the comprehensive characterization of major NL species has not been discussed. Here, a simple and adaptable method to quantify the de novo&#160;synthesis of major NL species in yeast is presented. We apply 14C-acetic acid metabolic labeling coupled with thin layer chromatography to separate and quantify a diverse range of physiologically important NLs. Additionally, this method can be easily applied to study in vivo reaction rates of NL enzymes or degradation of NL species over time.

Analysis of Neutral Lipid Synthesis in Saccharomyces cerevisiae by Metabolic Labeling and Thin Layer Chromatography

Here, a protocol is presented for the metabolic labeling of yeast with 14C-acetic acid, which is coupled with thin layer chromatography for the separation of neutral lipids.

Analyse der neutralen Lipidsynthese in Saccharomyces cerevisiae durch metabolische Markierung und Dünnschichtchromatographie

Neutral lipids (NLs) are a class of hydrophobic, chargeless biomolecules that play key roles in energy and lipid homeostasis. NLs are synthesized de ...

Preparation and Cryo-FIB micromachining of Saccharomyces cerevisiae for Cryo-Electron Tomography

Today, cryo-electron tomography (cryo-ET) is the only technique that can provide near-atomic resolution structural data on macromolecular complexes in situ. Owing to the strong interaction of an electron with the matter, high-resolution cryo-ET studies are limited to specimens with a thickness of less than 200 nm, which restricts the applicability of cryo-ET only to the peripheral regions of a cell. A complex workflow that comprises the preparation of thin cellular cross-sections by cryo-focused ion beam micromachining (cryo-FIBM) was introduced during the last decade to enable the acquisition of cryo-ET data from the interior of larger cells. We present a protocol for the preparation of cellular lamellae from a sample vitrified by plunge freezing utilizing Saccharomyces cerevisiae as a prototypical example of a eukaryotic cell with wide utilization in cellular and molecular biology research. We describe protocols for vitrification of S. cerevisiae into isolated patches of a few cells or a continuous monolayer of the cells on a TEM grid and provide a protocol for lamella preparation by cryo-FIB for these two samples.

Preparation and Cryo-FIB micromachining of Saccharomyces cerevisiae for Cryo-Electron Tomography

We present a protocol for lamella preparation of plunge frozen biological specimens by cryo-focused ion beam micromachining for high-resolution structural studies of macromolecules in situ with cryo-electron tomography. The presented protocol provides guidelines for the preparation of high-quality lamellae with high reproducibility for structural characterization of macromolecules inside the&#160;Saccharomyces cerevisiae.

Herstellung und Kryo-FIB-Mikrobearbeitung von Saccharomyces cerevisiae für die Kryo-Elektronentomographie

Today, cryo-electron tomography (cryo-ET) is the only technique that can provide near-atomic resolution structural data on macromolecular complexes in ...

Assessment of Submitochondrial Protein Localization in Budding Yeast Saccharomyces cerevisiae

Despite recent advances in the characterization of yeast mitochondrial proteome, the submitochondrial localization of a significant number of proteins remains elusive. Here, we describe a robust and effective method for determining the suborganellar localization of yeast mitochondrial proteins, which is considered a fundamental step during mitochondrial protein function elucidation. This method involves an initial step that consists of obtaining highly pure intact mitochondria. These mitochondrial preparations are then subjected to a subfractionation protocol consisting of hypotonic shock (swelling) and incubation with proteinase K (protease). During swelling, the outer mitochondrial membrane is selectively disrupted, allowing the proteinase K to digest proteins of the intermembrane space compartment. In parallel, to obtain information about the topology of membrane proteins, the mitochondrial preparations are initially sonicated, and then subjected to alkaline extraction with sodium carbonate. Finally, after centrifugation, the pellet and supernatant fractions from these different treatments are analyzed by SDS-PAGE and western blot. The submitochondrial localization as well as the membrane topology of the protein of interest is obtained by comparing its western blot profile with known standards.

Assessment of Submitochondrial Protein Localization in Budding Yeast Saccharomyces cerevisiae

Despite recent advances, many yeast mitochondrial proteins still remain with their functions completely unknown. This protocol provides a simple and reliable method to determine the submitochondrial localization of proteins, which has been fundamental for the elucidation of their molecular functions.

Beurteilung der Submitochondrialen Proteinlokalisation in angehender Hefe Saccharomyces cerevisiae

Despite recent advances in the characterization of yeast mitochondrial proteome, the submitochondrial localization of a significant number of proteins ...

Purification of Endogenous Drosophila Transient Receptor Potential Channels

Drosophila phototransduction is one of the fastest known G protein-coupled signaling pathways. To ensure the specificity and efficiency of this cascade, the calcium (Ca2+)-permeable cation channel, transient receptor potential (TRP), binds tightly to the scaffold protein, inactivation-no-after-potential D (INAD), and forms a large signaling protein complex with eye-specific protein kinase C (ePKC) and phospholipase C&#946;/No receptor potential A (PLC&#946;/NORPA). However, the biochemical properties of the Drosophila TRP channel remain unclear. Based on the assembling mechanism of INAD protein complex, a modified affinity purification plus competition strategy was developed to purify the endogenous TRP channel. First, the purified histidine (His)-tagged NORPA 863-1095 fragment was bound to Ni-beads and used as bait to pull down the endogenous INAD protein complex from Drosophila head homogenates. Then, excessive purified glutathione S-transferase (GST)-tagged TRP 1261-1275 fragment was added to the Ni-beads to compete with the TRP channel. Finally, the TRP channel in the supernatant was separated from the excessive TRP 1261-1275 peptide by size-exclusion chromatography. This method makes it possible to study the gating mechanism of the Drosophila TRP channel from both biochemical and structural angles. The electrophysiology properties of purified Drosophila TRP channels can also be measured in the future.

Purification of Endogenous Drosophila Transient Receptor Potential Channels

Based on the assembling mechanism of the INAD protein complex, in this protocol, a modified affinity purification plus competition strategy was developed to purify the endogenous Drosophila TRP channel.

Reinigung von endogenen Drosophila-Transientenrezeptor-Potentialkanälen

Drosophila phototransduction is one of the fastest known G protein-coupled signaling pathways. To ensure the specificity and efficiency of this cascade, ...

Motility of Single Molecules and Clusters of Bi-Directional Kinesin-5 Cin8 Purified from S. cerevisiae Cells

The mitotic bipolar kinesin-5 motors perform essential functions in spindle dynamics. These motors exhibit a homo-tetrameric structure with two pairs of catalytic motor domains, located at opposite ends of the active complex. This unique architecture enables kinesin-5 motors to crosslink and slide apart antiparallel spindle microtubules (MTs), thus providing the outwardly-directed force that separates the spindle poles apart. Previously, kinesin-5 motors were believed to be exclusively plus-end directed. However, recent studies revealed that several fungal kinesin-5 motors are minus-end directed at the single-molecule level and can switch directionality under various experimental conditions. The Saccharomyces cerevisiae kinesin-5 Cin8 is an example of such bi-directional motor protein: in high ionic strength conditions single molecules of Cin8 move in the minus-end direction of the MTs. It was also shown that Cin8 forms motile clusters, predominantly at the minus-end of the MTs, and such clustering allows Cin8 to switch directionality and undergo slow, plus-end directed motility. This article provides a detailed protocol for all steps of working with GFP-tagged kinesin-5 Cin8, from protein overexpression in S. cerevisiae cells and its purification to in vitro single-molecule motility assay. A newly developed method described here helps to differentiate between single molecules and clusters of Cin8, based on their fluorescence intensity. This method enables separate analysis of motility of single molecules and clusters of Cin8, thus providing the characterization of the dependence of Cin8 motility on its cluster size.

Motility of Single Molecules and Clusters of Bi-Directional Kinesin-5 Cin8 Purified from S. cerevisiae Cells

The bi-directional mitotic kinesin-5 Cin8 accumulates in clusters that split and merge during their motility. Accumulation in clusters also changes the velocity and directionality of Cin8. Here, a protocol for motility assays with purified Cin8-GFP and analysis of motile properties of single molecules and clusters of Cin8 is described.

Motilität einzelner Moleküle und Cluster von bidirektionalem Kinesin-5 Cin8, gereinigt aus S. cerevisiae-Zellen

The mitotic bipolar kinesin-5 motors perform essential functions in spindle dynamics. These motors exhibit a homo-tetrameric structure with two pairs of ...