Queremos agradecer a todos os membros do laboratório Dinman, incluindo Ashton Belew, Jack Karen, Musalga Sharmishtha, Sulima Sergey, Reddy Shivani, e Michael Rhodin pela sua ajuda e de entrada neste projeto. Este trabalho foi suportado por concessões de AM da American Heart Association (AHA 0630163N) e JDD do National Institutes of Health (5R01 GM058859-12). JAL foi apoiada por um americano e Reinvestimento Lei de Recuperação de 2009 suplemento para a concessão dos pais (3R01GM058859-11S1).

1. Preparação de uma cisteína cobrado Sulfolink resina <ol><li> Prepare Sulfolink resina (Pierce) em temperatura ambiente. </li><li> Lugar um total de 10 ml de uma suspensão de 50% dos Sulfolink gel de acoplamento, conforme fornecido pelo fabricante em dois frascos de 10 ml de plástico, com 5 ml distribuídos em cada frasco. </li><li> Brevemente frascos de centrífuga a 850 xg e remova cuidadosamente sobrenadantes. </li><li> Lave o gel três vezes em tampão de acoplamento (50 mM Tris, pH 8.5, 5 mM EDTA) pela ressuspensão as contas em 5 ml, centrifugação a 850 xg brevemente e remover o sobrenadante com uma pipeta. </li><li> Adicione cinco ml de uma solução 50 mM de L-cisteína em tampão de acoplamento em cada tubo e misture a polpa de 1 hora a 25 ° C. </li><li> Remover o residual L-cisteína por lavagem como descrito no passo 1.4 acima. </li><li> Ressuspender o gel em 10 ml de tampão de ligação [20 mM HEPES, pH 7.6, 5 mM Mg (OAc) 2, 60 mM NH 4 Cl, 2 mM DTT], e equilibrar a resina pela lavagem em 10 ml de tampão de ligação3 vezes como descrito no passo 1.4. Decantar resina em uma centrífuga de 10 ml coluna tampa, e armazenados a 4 ° C. A capacidade de resina para RNA ligação é ~ 20 A 260 unidades por ml. </li></ol> 2. Purificação cromatográfica dos ribossomos usando uma cisteína cobrado Sulfolink resina Nota: Se estiver trabalhando com uma cepa em que a atividade protease prova ser um problema, cocktails da inibição da protease pode ser usado em todos os buffers subseqüentes. <ol><li> Manter todos os componentes no gelo e preparar todas as soluções usando RNase água e filtração estéril. </li><li> Cultivar células de levedura durante a noite para meados log-fase (OD 595 = 0,6-1,2) em mídia apropriada. Pellet células por centrifugação, e lavar as células 1 grama em tampão de ligação e centrifugar a 3700 xg por 5 minutos a 4 ° C. </li><li> Ressuspender as células em 1 ml de tampão de ligação a um volume total aproximado de 2 ml, e interromper usando um volume igual de 0,5 milímetros contas de vidro refrigerados a 4 ° C ucantar uma Biospec Mini-bead beater (Bartlesville, OK). Amostras podem ser divididos em tubos múltiplos, conforme necessário. </li><li> Remove as células intactas, organelas, e os restos celulares por centrifugação a 30.000 xg por 30 minutos em uma Optima Max Beckman-Coulter ultracentrífuga E (Fullerton, CA). </li><li> Imediatamente antes da utilização, pellet da resina por um minuto a 1.000 xg para remover a solução de armazenamento. Dois ml de resina é usada para cada grama de células. </li><li> Remover sobrenadantes lisado celular a partir do spin-xg 30.000 (S30), tendo o cuidado de minimizar a contaminação tanto da fração lipídica no topo ou os restos de células na parte inferior dos tubos, e coloque diretamente na pasta Sulfolink cobrado. A camada lipídica podem ser evitados tanto por remoção ou empurrando para fora da pipeta após o ponta cruzou para o sobrenadante. </li><li> Incubar a mistura S30/Sulfolink no gelo sem misturar por 15 minutos. </li><li> Coloque as colunas em tubos cônicos de 15 ml e centrifugar a 1000 xg porr de um minuto. </li><li> Coloque as frações fluxo contínuo de volta para as colunas, misture com a mão, e incubar por mais 15 minutos no gelo. </li><li> Coloque as colunas em tubos cônicos de 15 ml e centrifugar a 1000 xg durante um minuto. Descartar o fluxo contínuo. </li><li> Cap colunas e adicionar 5 ml de tampão de ligação. Mix colunas à mão até ressuspenso, remover as tampas, e centrifugar a centrífuga a 1.000 xg colunas durante um minuto. Repita este protocolo de lavagem mais duas vezes. </li><li> Adicionar 1,5 ml de tampão de eluição (20 mM HEPES-KOH, pH 7,6, 10 mM Mg (OAc) 2, 500 mM KCl, 2mM DTT, 0,5 mg / ml de heparina) para cada coluna. Mix de suspensões por mão, e incubar no gelo por 2 minutos </li><li> Colunas lugar em novos tubos de 15 ml cônico e centrifugar a 1000 xg por 1 minuto. Coletar eluído. Repita o passo de eluição mais uma vez para que o final de volumes de amostra são combinados ~ 3 ml. Resina utilizada pode ser lavado com tampão de eluição sem heparina e seguida de equilíbrio com Buffe vinculativor, e armazenados em volumes de 10 ml de tampão de ligação a 4 ° C para reutilização posterior. </li></ol> 3. Tratamento puromicina Nota: Um método alternativo para remover contaminantes espécies tRNA é mudar a partir de uma glucose ricos em mídia de glicose esgotados para promover o escoamento ribossomo. No entanto, isso muda o estado metabólico das células de levedura, o que poderia afetar a função do ribossomo e concentração. , A fim de strip os ribossomos a partir endógena peptidil-tRNA, um tratamento com puromicina é executada. <ol><li> Neutralize a solução de pH 7,5 puromicina 100 mM KOH 1M, adicionando gota a gota à temperatura ambiente. </li><li> Adicionar solução puromicina neutralizado para ~ concentração 1mM final no eluído. </li><li> Adicionar 100 mM GTP para uma concentração final de 1 mM. </li><li> Incubar por 30 minutos a 30 ° C. </li></ol> 4. Purificação dos ribossomos por sedimentação através de coxins de glicerol <ol><li> Coloque um mlalmofada de tampão (20 mM HEPES, pH 7.6, 10 mM Mg (OAc) 2, 500 mM KCl, 2 mM DTT, glicerol 25%) em um tubo de volume 4 ml ultracentrífuga policarbonato. </li><li> Suavemente camada puromicina tratados frações de eluição em cima da almofada, e amostras de centrifugação a 100.000 xg durante a noite a 4 ° C. </li><li> Remover os tubos do rotor de centrífuga, e aspire sobrenadantes. </li><li> Lavar pellets contendo ribossomos purificada duas vezes com 1 ml de tampão almofada. </li><li> Ressuspender ribossomos em 100 l de tampão almofada pela ruptura suave usando uma vareta de vidro. </li><li> Após interrupção, cobrir os tubos com parafilme e agite a uma velocidade moderada em um vórtice sala fria durante uma hora. </li><li> Transferir o conteúdo para um tubo de microcentrífuga, centrífuga por 5 minutos na velocidade máxima a 4 ° C, e remover sobrenadante para tubos fresco. </li><li> Repita os passos de 4,1-4,7 utilizando 2 ml de tampão almofada e, exceto pelo fato de 100 mL de buffer de armazenamento (50 mM HEPES-KOH pH 7,6, 50 mM NH 4 Cl, 5 mM Mg(OAc) 2, 1 mM DTT, glicerol 25%) é usado em passos 4.4 e 4.5 ao invés de tampão almofada. </li><li> Quantificar os ribossomos purificada espectrofotometricamente (1 A 260 = 20 pmoles dos ribossomos de levedura), e armazenar a -80 ° C. Os resultados típicos a partir de 1 grama de levedura são 300-400 pmoles dos ribossomos. </li></ol> 5. Resultados representativos: Um exemplo de espécies de RNA extraído de cada uma das três etapas principais do protocolo é mostrado na Figura 2. Enquanto rRNAs são as principais espécies presentes em lisados ​​celulares total (T) estes também contêm um grande número de outras espécies de RNA. Ribossomos purificada a partir da coluna Sulfolink (SL) também contêm uma grande quantidade de tRNAs devido à alta afinidade da cama coluna para estas espécies também. Tratamento desta fração com resultados puromicina na hidrólise de peptídeos de peptidil-tRNAs, e promove a dissociação dessas espécies de ribossomos. A puromicina amostras tratadas falta (Pm) co-purifyinespécies g tRNA, e, portanto, representam ribossomos completamente puro. Como relatado anteriormente 8, essas ribossomos são altamente intacta e bioquimicamente ativas, tornando-os ideais para substratos detalhadas análises funcionais e estruturais. <img src="/files/ftp_upload/3214/3214fig1.jpg" alt="Figura 1"/> Figura 1. Fluxograma do método. Purificação cromatográfica dos ribossomos usando a cisteína ligados sulfolink resina é retratado. <img src="/files/ftp_upload/3214/3214fig2.jpg" alt="Figura 2"/> Figura 2. Análise representativa das preparações ribossomo. Espécies de RNA total foram extraídas de lisados ​​celulares total (T), ribossomos Sulfolink purificada (SL) e Sulfolink purificada ribossomos posteriormente tratados com puromicina e sedimentada através de uma almofada de glicerol (Pm). Pista M representa marcadores de tamanho RNA. Bandas representando rRNAs 25S e 18S, bem como tRNAs e outras espécies de RNA são indicados. Todospistas foram carregados com 2 mg de RNA.

<ol>
	<li>Palade, G. E., Siekevitz, P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Liver+microsomes;+an+integrated+morphological+and+biochemical+study.">Liver microsomes; an integrated morphological and biochemical study.</a> J. Biophys. Biochem. Cytol. 2, 171-200 (1956).</li><li>Fabry, M., Kalvoda, L., Rychlik, I. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Hydrophobic+interactions+of+Escherichia+coli+ribosomes.">Hydrophobic interactions of Escherichia coli ribosomes.</a> Biochim. Biophys. Acta. 652, 139-150 (1981).</li><li>Jelenc, P. C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Rapid+purification+of+highly+active+ribosomes+from+Escherichia+coli.">Rapid purification of highly active ribosomes from Escherichia coli.</a> Anal. Biochem. 105, 369-374 (1980).</li><li>Le goffic, F., Moreau, N., Chevelot, L., Langrene, S., Siegrist, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Purification+of+bacterial+ribosomes+using+chloramphenicol+and+erythromycin+columns.">Purification of bacterial ribosomes using chloramphenicol and erythromycin columns.</a> Biochimie. 62, 69-77 (1980).</li><li>Meskauskas, A., Petrov, A. N., Dinman, J. D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Identification+of+functionally+important+amino+acids+of+ribosomal+protein+L3+by+saturation+mutagenesis.">Identification of functionally important amino acids of ribosomal protein L3 by saturation mutagenesis.</a> Mol. Cell Biol. 25, 10863-10874 (2005).</li><li>Algire, M. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Development+and+characterization+of+a+reconstituted+yeast+translation+initiation+system.">Development and characterization of a reconstituted yeast translation initiation system.</a> RNA. 8, 382-397 (2002).</li><li>Maguire, B. A., Wondrack, L. M., Contillo, L. G., Xu, Z. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+novel+chromatography+system+to+isolate+active+ribosomes+from+pathogenic+bacteria.">A novel chromatography system to isolate active ribosomes from pathogenic bacteria.</a> RNA. 14, 188-195 (2008).</li><li>Leshin, J. A., Rakauskaite, R., Dinman, J. D., Meskauskas, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Enhanced+purity,+activity+and+structural+integrity+of+yeast+ribosomes+purified+using+a+general+chromatographic+method.">Enhanced purity, activity and structural integrity of yeast ribosomes purified using a general chromatographic method.</a> RNA. Biol. 7, 354-360 (2010).</li><li>Triana, F., Nierhaus, K. 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A. 70, 3866-3869 (1973).</li><li>Nathans, D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Puromuycin+inhibition+of+protein+synthesis:+incorporation+of+puromycin+into+peptide+chains.">Puromuycin inhibition of protein synthesis: incorporation of puromycin into peptide chains.</a> Proc. Natl. Acad. Sci. U. S. A. 51, 585-592 (1964).</li><li>Rabinovitz, M., Fisher, J. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+dissociative+effect+of+puromycin+on+the+pathway+of+protein+synthesis+by+Ehrlich+ascites+tumor+cells.">A dissociative effect of puromycin on the pathway of protein synthesis by Ehrlich ascites tumor cells.</a> J. Biol. Chem. 237, 477-481 (1962).</li><li>Allen, D. W., Zamecnik, P. 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A. 45, 1721-1729 (1959).</li><li>Becker-Ursic, D., Davies, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=In+vivo+and+in+vitro+phosphorylation+of+ribosomal+proteins+by+protein+kinases+from+Saccharomyces+cerevisiae.">In vivo and in vitro phosphorylation of ribosomal proteins by protein kinases from Saccharomyces cerevisiae.</a> Biochemistry. 15, 2289-2296 (1976).</li></ol>

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Protocolos de purificação de ribossomo basicamente envolvem as células de lise, colhendo uma fração citosólica de uma rotação baixa velocidade, e depois de granulação ribossomos por centrifugação de alta velocidade 1. Enquanto uma novela poucos métodos têm sido utilizados para a purificação ribossomos bacterianos, o mesmo não tinha sido verdade para eucariontes 2-4. Embora as etapas foram adicionadas ao longo dos anos, lava o sal por exemplo, almofadas e glicerol (por exemplo, ver ...

<table border="1"><tbody><tr><td> Nome do reagente </td><td> Companhia </td><td> Número de catálogo </td></tr><tr><td> Sulfolink resina Coupling </td><td> Perfurar </td><td> 20402 </td></tr><tr><td> Mini-bead beater 16 </td><td> Biospec </td><td> 607 </td></tr><tr><td> Optima Max ultracentrífuga E </td><td> Beckman Coulter </td><td></td></tr><tr><td> Legenda RT </td><td> Sorvall </td><td></td></tr><tr><td> 0,5 milímetros Contas de vidro </td><td> Biospec </td><td> 11079105 </td></tr><tr><td> Tris </td><td> Sigma-Aldrich </td><td> 252859 </td></tr><tr><td> EDTA </td><td> Sigma-Aldrich </td><td> E9884 </td></tr><tr><td> TDT </td><td> Sigma-Aldrich </td><td> 43815 </td></tr><tr><td> HEPES </td><td> Sigma-Aldrich </td><td> 54459 </td></tr><tr><td> NH 4 Cl </td><td> Sigma-Aldrich </td><td> A9434 </td></tr><tr><td> KCl </td><td> Sigma-Aldrich </td><td> 60128 </td></tr><tr><td> Mg (OAc) 2 </td><td> Sigma-Aldrich </td><td> M5661 </td></tr><tr><td> KOH </td><td> Sigma-Aldrich </td><td> 221473 </td></tr><tr><td> Glicerina </td><td> Sigma-Aldrich </td><td> G5516 </td></tr><tr><td> Puromicina </td><td> Sigma-Aldrich </td><td> P7255 </td></tr><tr><td> GTP </td><td> Fermentas </td><td> R0461 </td></tr></tbody></table>

chromatographic purification of highly active yeast ribosomes

Ribossomos eucarióticos são muito mais instável, em comparação com os seus homólogos eubacterianas archael e, desta forma criando um grande desafio para os pesquisadores. Particularmente problemático é o fato de que a lise de células libera um grande número de proteases e nucleases que podem degradar os ribossomos. Assim, é importante separar os ribossomos a partir destas enzimas o mais rápido possível. Infelizmente, os métodos convencionais ultracentrifugação diferencial deixa ribossomos expostos a estas enzimas por períodos inaceitavelmente longos de tempo, afetando sua integridade estrutural e funcionalidade. Para resolver este problema, nós utilizamos um método de cromatografia usando uma cisteína cobrado Sulfolink resina. Esta aplicação simples e rápido reduz significativamente co purificação de atividades proteolíticas e nucleolytic, produzindo altos rendimentos de intacto, ribossomos de levedura altamente bioquimicamente ativas. Sugerimos que este método também deve ser aplicável a ribossomos de mamíferos. A simplicidade deo método ea pureza maior e atividade do ribossomo purificada cromatograficamente representa um avanço técnico significativo para o estudo dos ribossomos eucarióticos.

Watch this Scientific Journal Video about Chromatographic Purification of Highly Active Yeast Ribosomes at JoVE.com

Chromatographic Purification of Highly Active Yeast Ribosomes

Contaminação de preparações dos ribossomos eucarióticos purificado por métodos tradicionais de co purificação de proteases e nucleases negativamente impactos sobre a jusante análises bioquímicas e estruturais. Um método de purificação cromatográfica rápida e simples é usado para resolver esse problema usando os ribossomos de levedura como um sistema modelo.

Purificação cromatográfica de Ribossomos Yeast Highly Active

Eukaryotic ribosomes are much more labile as compared to their eubacterial and archael counterparts, thus posing a significant challenge to researchers.  ...

chromatographic-purification-of-highly-active-yeast-ribosomes

Research

JoVE Journal

Biology

16.8K visualizações.  University of Maryland. Contaminação de preparações dos ribossomos eucarióticos purificado por métodos tradicionais de co purificação de proteases e nucleases negativamente impactos sobre a jusante análises bioquímicas e estruturais. Um método de purificação cromatográfica rápida e simples é usado para resolver esse problema usando os ribossomos de levedura como um sistema modelo.

Vídeo: Chromatographic Purification of Highly Active Yeast Ribosomes

Staining of Proteins in Gels with Coomassie G-250 without Organic Solvent and Acetic Acid

In classical protein staining protocols using Coomassie Brilliant Blue (CBB), solutions with high contents of toxic and flammable organic solvents (Methanol, Ethanol or 2-Propanol) and acetic acid are used for fixation, staining and destaining of proteins in a gel after SDS-PAGE. To speed up the procedure, heating the staining solution in the microwave oven for a short time is frequently used. This usually results in evaporation of toxic or hazardous Methanol, Ethanol or 2-Propanol and a strong smell of acetic acid in the lab which should be avoided due to safety considerations. In a protocol originally published in two patent applications by E.M. Wondrak (US2001046709 (A1), US6319720 (B1)), an alternative composition of the staining solution is described in which no organic solvent or acid is used. The CBB is dissolved in bidistilled water (60-80mg of CBB G-250 per liter) and 35 mM HCl is added as the only other compound in the staining solution. The CBB staning of the gel is done after SDS-PAGE and thorough washing of the gel in bidistilled water. By heating the gel during the washing and staining steps, the process can be finished faster and no toxic or hazardous compunds are evaporating. The staining of proteins occurs already within 1 minute after heating the gel in staining solution and is fully developed after 15-30 min with a slightly blue background that is destained completely by prolonged washing of the stained gel in bidistilled water, without affecting the stained protein bands.

A short protocol for protein staining with Coomassie Brilliant Blue (CBB) G-250 in polyacrylamide gels is described without using organic solvents or acetic acid as in the classical staining procedures with CBB.

Coloração de proteínas em géis com Coomassie G-250 sem ácido acético e Solventes Orgânicos

In classical protein staining protocols using Coomassie Brilliant Blue (CBB), solutions with high contents of toxic and flammable organic solvents ...

Biologia

Purification of Mitochondria from Yeast Cells

Mitochondria are the main site of ATP production during aerobic metabolism in eukaryotic non-photosynthetic cells1. These complex organelles also play essential roles in apoptotic cell death2, cell survival3, mammalian development4, neuronal development and function4, intracellular signalling5, and longevity regulation6. Our understanding of these complex biological processes controlled by mitochondria relies on robust methods for assessing their morphology, their protein and lipid composition, the integrity of their DNA, and their numerous vital functions. The budding yeast Saccharomyces cerevisiae, a genetically and biochemically manipulable unicellular eukaryote with annotated genome and well-defined proteome, is a valuable model for studying the molecular and cellular mechanisms underlying essential biological functions of mitochondria. For these types of studies, it is crucial to have highly pure mitochondria. Here we present a detailed description of a rapid and effective method for purification of yeast mitochondria. This method enables the isolation of highly pure mitochondria that are essentially free of contamination by other organelles and retain their structural and functional integrity after their purification. Mitochondria purified by this method are suitable for cell-free reconstitution of essential mitochondrial processes and can be used for the analysis of mitochondrial structure and functions, mitochondrial proteome and lipidome, and mitochondrial DNA.

We describe a rapid and effective method for purification of mitochondria from the yeast Saccharomyces cerevisiae. This method enables the high-yield isolation of pure mitochondria that are essentially free of contamination by other organelles and retain their structural and functional integrity after their purification.

Purificação de mitocôndrias de células de levedura

Mitochondria are the main site of ATP production during aerobic metabolism in eukaryotic non-photosynthetic cells1. These complex organelles also play ...

Preparation of Highly Coupled Rat Heart Mitochondria

The function of mitochondria in generation of cellular ATP in the process of oxidative phosphorylation is widely recognised. During the past decades there have been significant advances in our understanding of the functions of mitochondria other than the generation of energy. These include their role in apoptosis, acting as signalling organelles, mammalian development and ageing as well as their contribution to the coordination between cell metabolism and cell proliferation. Our understanding of biological processes modulated by mitochondria is based on robust methods for isolation and handling of intact mitochondria from tissues of the laboratory animals. Mitochondria from rat heart is one of the most common preparations for past and current studies of cellular metabolism including studies on knock-out animals.
Here we describe a detailed rapid method for isolation of intact mitochondria with a high degree of coupling. Such preparation of rat heart mitochondria is an excellent object for functional and structural research on cellular bioenergetics, transport of biomolecules, proteomic studies and analysis of mitochondrial DNA, proteins and lipids.

We describe &#1072; protocol for isolation of pure, highly coupled rat heart mitochondria for functional or structural studies of cellular bioenergetics, biophysical measurements, proteomics or mitochondrial DNA and lipids analysis.

Preparação de coração de rato altamente acoplado mitocôndrias

The function of mitochondria in generation of cellular ATP in the process of oxidative phosphorylation is widely recognised. During the past decades there ...

Isolation of Translating Ribosomes Containing Peptidyl-tRNAs for Functional and Structural Analyses

Recently, structural and biochemical studies have detailed many of the molecular events that occur in the ribosome during inhibition of protein synthesis by antibiotics and during nascent polypeptide synthesis. Some of these antibiotics, and regulatory nascent polypeptides mostly in the form of peptidyl-tRNAs, inhibit either peptide bond formation or translation termination1-7. These inhibitory events can stop the movement of the ribosome, a phenomenon termed "translational arrest". Translation arrest induced by either an antibiotic or a nascent polypeptide has been shown to regulate the expression of genes involved in diverse cellular functions such as cell growth, antibiotic resistance, protein translocation and cell metabolism8-13. Knowledge of how antibiotics and regulatory nascent polypeptides alter ribosome function is essential if we are to understand the complete role of the ribosome in translation, in every organism.
Here, we describe a simple methodology that can be used to purify, exclusively, for analysis, those ribosomes translating a specific mRNA and containing a specific peptidyl-tRNA14. This procedure is based on selective isolation of translating ribosomes bound to a biotin-labeled mRNA. These translational complexes are separated from other ribosomes in the same mixture, using streptavidin paramagnetic beads (SMB) and a magnetic field (MF). Biotin-labeled mRNAs are synthesized by run-off transcription assays using as templates PCR-generated DNA fragments that contain T7 transcriptional promoters. T7 RNA polymerase incorporates biotin-16-UMP from biotin-UTP; under our conditions approximately ten biotin-16-UMP molecules are incorporated in a 600 nt mRNA with a 25% UMP content. These biotin-labeled mRNAs are then isolated, and used in in vitro translation assays performed with release factor 2 (RF2)-depleted cell-free extracts obtained from Escherichia coli strains containing wild type or mutant ribosomes. Ribosomes translating the biotin-labeled mRNA sequences are stalled at the stop codon region, due to the absence of the RF2 protein, which normally accomplishes translation termination. Stalled ribosomes containing the newly synthesized peptidyl-tRNA are isolated and removed from the translation reactions using SMB and an MF. These beads only bind biotin-containing messages.
The isolated, translational complexes, can be used to analyze the structural and functional features of wild type or mutant ribosomal components, or peptidyl-tRNA sequences, as well as determining ribosome interaction with antibiotics or other molecular factors 1,14-16. To examine the function of these isolated ribosome complexes, peptidyl-transferase assays can be performed in the presence of the antibiotic puromycin1. To study structural changes in translational complexes, well established procedures can be used, such as i) crosslinking to specific amino acids14 and/or ii) alkylation protection assays1,14,17.

A major impediment to biochemical analyses of ribosomes containing nascent peptidyl-tRNAs has been the presence of other ribosomes in the same samples, ribosomes not involved in the translation of the specific mRNA sequence being analyzed. We developed a simple methodology to purify, exclusively, the ribosomes containing the nascent peptidyl-tRNA of interest.

Isolamento de Ribossomos Traduzindo Contendo peptidil-tRNAs para análises funcionais e estruturais

Recently, structural and biochemical studies have detailed many of the molecular events that occur in the ribosome during inhibition of protein synthesis ...

Yeast Colony Embedding Method

Patterning of different cell types in embryos is a key mechanism in metazoan development. Communities of microorganisms, such as colonies and biofilms also display patterns of cell types. For example, in the yeast S. cerevisiae, sporulated cells and pseudohyphal cells are not uniformly distributed in colonies. The functional importance of patterning and the molecular mechanisms that underlie these patterns are still poorly understood.
One challenge with respect to investigating patterns of cell types in fungal colonies is that unlike metazoan tissue, cells in colonies are relatively weakly attached to one another. In particular, fungal colonies do not contain the same extensive level of extracellular matrix found in most tissues . Here we report on a method for embedding and sectioning yeast colonies that reveals the interior patterns of cell types in these colonies. The method can be used to prepare thick sections (0.5 &mu;) useful for light microscopy and thin sections (0.1 &mu;) suitable for transmission electron microscopy. Asci and pseudohyphal cells can easily be distinguished from ovoid yeast cells by light microscopy , while the interior structure of these cells can be visualized by EM.
The method is based on surrounding colonies with agar, infiltrating them with Spurr's medium, and then sectioning. Colonies with a diameter in the range of 1-2 mm are suitable for this protocol. In addition to visualizing the interior of colonies, the method allows visualization of the region of the colony that invades the underlying agar.

A method for embedding yeast colonies allowing sectioning for light and electron microscopy. This protocol allows determination of the distribution of sporulated cells and pseudohyphal cells within colonies providing a new tool toward understanding the organization of cell types within a fungal community.

Levedura Método Embedding Colony

Patterning of  different cell types in embryos is a key mechanism in metazoan development. Communities of microorganisms, such as colonies and biofilms ...

In vitro Reconstitution of the Active T. castaneum Telomerase

Efforts to isolate the catalytic subunit of telomerase, TERT, in sufficient quantities for structural studies, have been met with limited success for more than a decade. Here, we present methods for the isolation of the recombinant Tribolium castaneum TERT (TcTERT) and the reconstitution of the active T. castaneum telomerase ribonucleoprotein (RNP) complex in vitro.
Telomerase is a specialized reverse transcriptase1 that adds short DNA repeats, called telomeres, to the 3' end of linear chromosomes2 that serve to protect them from end-to-end fusion and degradation. Following DNA replication, a short segment is lost at the end of the chromosome3 and without telomerase, cells continue dividing until eventually reaching their Hayflick Limit4. Additionally, telomerase is dormant in most somatic cells5 in adults, but is active in cancer cells6 where it promotes cell immortality7.
The minimal telomerase enzyme consists of two core components: the protein subunit (TERT), which comprises the catalytic subunit of the enzyme and an integral RNA component (TER), which contains the template TERT uses to synthesize telomeres8,9. Prior to 2008, only structures for individual telomerase domains had been solved10,11. A major breakthrough in this field came from the determination of the crystal structure of the active12, catalytic subunit of T. castaneum telomerase, TcTERT1.
Here, we present methods for producing large quantities of the active, soluble TcTERT for structural and biochemical studies, and the reconstitution of the telomerase RNP complex in vitro for telomerase activity assays. An overview of the experimental methods used is shown in Figure 1.

In vitro Reconstitution of the Active T. castaneum Telomerase

Efforts to isolate the catalytic subunit of telomerase, TERT, in sufficient quantities for structural studies, have been met with limited success for more than a decade. Here, we present methods for the isolation of the recombinant Tribolium castaneum TERT (TcTERT) and the reconstitution of the active T. castaneum telomerase ribonucleoprotein (RNP) complex in vitro.

Na reconstituição in vitro da atividade T. Telomerase castaneum

Efforts to isolate the catalytic subunit of telomerase, TERT, in sufficient quantities for structural studies, have been met with limited success for more ...

High-throughput Yeast Plasmid Overexpression Screen

The budding yeast, Saccharomyces cerevisiae, is a powerful model system for defining fundamental mechanisms of many important cellular processes, including those with direct relevance to human disease. Because of its short generation time and well-characterized genome, a major experimental advantage of the yeast model system is the ability to perform genetic screens to identify genes and pathways that are involved in a given process. Over the last thirty years such genetic screens have been used to elucidate the cell cycle, secretory pathway, and many more highly conserved aspects of eukaryotic cell biology 1-5. In the last few years, several genomewide libraries of yeast strains and plasmids have been generated 6-10. These collections now allow for the systematic interrogation of gene function using gain- and loss-of-function approaches 11-16. Here we provide a detailed protocol for the use of a high-throughput yeast transformation protocol with a liquid handling robot to perform a plasmid overexpression screen, using an arrayed library of 5,500 yeast plasmids. We have been using these screens to identify genetic modifiers of toxicity associated with the accumulation of aggregation-prone human neurodegenerative disease proteins. The methods presented here are readily adaptable to the study of other cellular phenotypes of interest.

Here we describe a plasmid overexpression screen in Saccharomyces cerevisiae, using an arrayed plasmid library and a high-throughput yeast transformation protocol with a liquid handling robot.

Alto rendimento Yeast Tela superexpressão Plasmid

The budding yeast, Saccharomyces cerevisiae, is a powerful model system for defining fundamental mechanisms of many important cellular processes, ...

Competitive Genomic Screens of Barcoded Yeast Libraries

By virtue of advances in next generation sequencing technologies, we have access to new genome sequences almost daily. The tempo of these advances is accelerating, promising greater depth and breadth. In light of these extraordinary advances, the need for fast, parallel methods to define gene function becomes ever more important. Collections of genome-wide deletion mutants in yeasts and E. coli have served as workhorses for functional characterization of gene function, but this approach is not scalable, current gene-deletion approaches require each of the thousands of genes that comprise a genome to be deleted and verified. Only after this work is complete can we pursue high-throughput phenotyping. Over the past decade, our laboratory has refined a portfolio of competitive, miniaturized, high-throughput genome-wide assays that can be performed in parallel. This parallelization is possible because of the inclusion of DNA 'tags', or 'barcodes,' into each mutant, with the barcode serving as a proxy for the mutation and one can measure the barcode abundance to assess mutant fitness. In this study, we seek to fill the gap between DNA sequence and barcoded mutant collections. To accomplish this we introduce a combined transposon disruption-barcoding approach that opens up parallel barcode assays to newly sequenced, but poorly characterized microbes. To illustrate this approach we present a new Candida albicans barcoded disruption collection and describe how both microarray-based and next generation sequencing-based platforms can be used to collect 10,000 - 1,000,000 gene-gene and drug-gene interactions in a single experiment.

We have developed comprehensive, unbiased genome-wide screens to understand gene-drug and gene-environment interactions. Methods for screening these mutant collections are presented.

Competitiva Screens Genomic de Bibliotecas Yeast Barcoded

By virtue of advances in next generation sequencing technologies, we have access to new genome sequences almost daily.  The tempo of these advances is ...

Budding Yeast Protein Extraction and Purification for the Study of Function, Interactions, and Post-translational Modifications

Homogenization by bead beating is a fast and efficient way to release DNA, RNA, proteins, and metabolites from budding yeast cells, which are notoriously hard to disrupt. Here we describe the use of a bead mill homogenizer for the extraction of proteins into buffers optimized to maintain the functions, interactions and post-translational modifications of proteins. Logarithmically growing cells expressing the protein of interest are grown in a liquid growth media of choice. The growth media may be supplemented with reagents to induce protein expression from inducible promoters (e.g. galactose), synchronize cell cycle stage (e.g. nocodazole), or inhibit proteasome function (e.g. MG132). Cells are then pelleted and resuspended in a suitable buffer containing protease and/or phosphatase inhibitors and are either processed immediately or frozen in liquid nitrogen for later use. Homogenization is accomplished by six cycles of 20 sec&#160;bead-beating (5.5 m/sec), each followed by one minute incubation on ice. The resulting homogenate is cleared by centrifugation and small particulates can be removed by filtration. The resulting cleared whole cell extract (WCE) is precipitated using 20% TCA for direct analysis of total proteins by SDS-PAGE followed by Western blotting. Extracts are also suitable for affinity purification of specific proteins, the detection of post-translational modifications, or the analysis of co-purifying proteins. As is the case for most protein purification protocols, some enzymes and proteins may require unique conditions or buffer compositions for their purification and others may be unstable or insoluble under the conditions stated. In the latter case, the protocol presented may provide a useful starting point to empirically determine the best bead-beating strategy for protein extraction and purification. We show the extraction and purification of an epitope-tagged SUMO E3 ligase, Siz1, a cell cycle regulated protein that becomes both sumoylated and phosphorylated, as well as a SUMO-targeted ubiquitin ligase subunit, Slx5.

The preparation of high quality yeast cell extracts is a necessary first step in the analysis of individual proteins or entire proteomes. Here we describe a fast, efficient, and reliable homogenization protocol for budding yeast cells that has been optimized to preserve protein functions, interactions, and post-translational modifications.

Brotando Yeast extração e purificação de proteínas para o estudo da função, interações e modificações pós-traducionais

Homogenization by bead beating is a fast and efficient way to release DNA, RNA, proteins, and metabolites from budding yeast cells, which are notoriously ...

Non-chromatographic Purification of Recombinant Elastin-like Polypeptides and their Fusions with Peptides and Proteins from Escherichia coli

Elastin-like polypeptides are repetitive biopolymers that exhibit a lower critical solution temperature phase transition behavior, existing as soluble unimers below a characteristic transition temperature and aggregating into micron-scale coacervates above their transition temperature. The design of elastin-like polypeptides at the genetic level permits precise control of their sequence and length, which dictates their thermal properties. Elastin-like polypeptides are used in a variety of applications including biosensing, tissue engineering, and drug delivery, where the transition temperature and biopolymer architecture of the ELP can be tuned for the specific application of interest. Furthermore, the lower critical solution temperature phase transition behavior of elastin-like polypeptides allows their purification by their thermal response, such that their selective coacervation and resolubilization allows the removal of both soluble and insoluble contaminants following expression in Escherichia coli. This approach can be used for the purification of elastin-like polypeptides alone or as a purification tool for peptide or protein fusions where recombinant peptides or proteins genetically appended to elastin-like polypeptide tags can be purified without chromatography. This protocol describes the purification of elastin-like polypeptides and their peptide or protein fusions and discusses basic characterization techniques to assess the thermal behavior of pure elastin-like polypeptide products.

Non-chromatographic Purification of Recombinant Elastin-like Polypeptides and their Fusions with Peptides and Proteins from Escherichia coli

Elastin-like polypeptides are stimulus-responsive biopolymers with applications ranging from recombinant protein purification to drug delivery. This protocol describes the purification and characterization of elastin-like polypeptides and their peptide or protein fusions from Escherichia coli using their lower critical solution temperature phase transition behavior as a simple alternative to chromatography.

A purificação cromatográfica do não-polipéptidos recombinantes Elastina semelhantes e suas fusões com Peptídeos e Proteínas de<em&gt; Escherichia coli</em

Elastin-like polypeptides are repetitive biopolymers that exhibit a lower critical solution temperature phase transition behavior, existing as soluble ...