Questa ricerca è stato originariamente pubblicato in Mol Proteomica cellulari. Soldi M. Bonaldi T. La Proteomica Indagine della cromatina domini funzionali rivela Nuove sinergie tra distinte Eterocromatina Componenti MCP. 2013; 12: 64-80. © Società Americana per la Biochimica e Biologia Molecolare. Ringraziamo Roberta Noberini (Istituto Italiano di Tecnologia e IEO, Italia) per la lettura critica del manoscritto. Lavoro TB è sostenuto da finanziamenti della Fondazione Armenise-Harvard Career Development Program Giovanni, l&#39;Associazione Italiana per la Ricerca sul Cancro e il Ministero della Salute italiano. Lavoro MS è stato sostenuto da una borsa di studio FIRC.

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Nessun conflitto di interessi dichiarati.

Abbiamo recentemente descritto ChroP, una strategia quantitativa per la caratterizzazione su larga scala dei componenti proteici della cromatina. ChroP combina due approcci complementari utilizzati in campo epigenetico, Chip e MS, approfittando loro punti di forza e superando i rispettivi limiti. ChIP accoppiato al sequenziamento profondo (ChIP-Seq) consente la mappatura genoma di modificazioni degli istoni alla risoluzione di alcune nucleosomi 35. Pur vantaggiosa per la loro sensibilità, saggi basati su anticorpi sono limitati nella loro capacità di distinguere modifiche simili e nella sezionare l&#39;aspetto combinatorio del codice dell&#39;istone 36. D&#39;altra parte, mentre MS fornisce un&#39;analisi completa e obiettiva hPTMs, singolarmente o in combinazione 9, è stato finora applicato all&#39;analisi della cromatina rinfusa, con conseguente mancanza di informazioni su specifici locus PTMs schemi. Ci avvaliamo di una versione modificata del circuito integrato per isolare funzionalmentedomini di cromatina distinti e spettrometria di massa per caratterizzare i modelli istone PTM e le proteine ​​non istoniche specificamente co-arricchiti. Utilizzando N-ChroP, l&#39;analisi di hPTMs co-associati H3K9me3 rivelato un arricchimento significativo di marcatori associati con cromatina silenziosa, e un impoverimento di modifiche associati cromatina attiva. L&#39;accordo di questi risultati con gli studi precedenti 37 ha dimostrato la robustezza della strategia. In X-ChroP di domini H3K9me3, l&#39;inchiesta basata SILAC-delle proteine ​​della cromatina interagiscono confermato alcuni interattori precedentemente descritti, convalidando così il metodo. ChroP presenta due principali aspetti originali rispetto alle strategie già disponibili per indagare la componente proteomica di cromatina: per esempio, la possibilità di rivelare sinergie inter-molecolari tra modifiche decorare istoni principali distinte all&#39;interno della stessa intatta mono-Nucleosome purificato da N-chip; seconda la possibilità di valutare la compartimentazione specifica di varianti istoniche e linker sottotipi istoni. Poiché la ricerca di varianti dell&#39;istone è frenato dalla mancanza di reagenti di buona qualità (cioè anticorpi), ChroP emerge come unico strumento a disposizione per valutare la loro posizione e ruolo funzionale. Una limitazione del ChroP nella sua attuale istituito bugie in peptide-centric (&quot;Bottom-up&quot;) approccio utilizzato nella SM, con istoni digerito in piccoli peptidi e la conseguente perdita di valore nel rilevare la connettività a lunga distanza tra modifiche. Come tale, la coniugazione di ChroP con &quot;bottom-up&quot; analisi MS consente una valutazione parziale dell&#39;aspetto combinatoria del codice istoni. Prevediamo che l&#39;attuazione di strategie alternative MS, come &quot;-Middle e Top-Down&quot; per la mappatura hPTMs su peptidi più lunghi (&gt; 20 aa) fino a proteine ​​intatte 38-40, supereràquesto moderazione. Nel complesso, N e X-ChroP sono altamente complementari, con la possibilità di sezionare la complessità della struttura della cromatina in domini funzionalmente distinte, con una risoluzione di mono-di oligo-nucleosomi. Prevediamo che ChroP sarà utile anche per caratterizzare la composizione delle regioni cromatina segnati dalla presenza di proteine ​​nucleari non istoniche specifici, per esempio fattori di trascrizione (TFS). Inoltre, ChroP può essere impiegato in studi funzionali per mappare la composizione dinamica della cromatina in loci specifici su varie perturbazioni, ad esempio durante l&#39;attivazione trascrizionale globale. Per queste ragioni, ChroP emerge come un utile strumento aggiuntivo nel arsenale di strategie analitiche disponibili per sezionare il paesaggio proteomica della cromatina.

Cromatina è un complesso nucleoproteina altamente dinamico che è coinvolto come modello primario per tutti i processi di DNA-mediata. Il nucleosoma è l&#39;unità ripetuta di base della cromatina e costituito da un nucleo octameric proteica contenente due molecole di ciascun istone H2A canonica, H2B, H3 e H4, attorno al quale 147 bp di DNA sono avvolte 1,2. Tutti gli istoni fondamentali sono strutturati come un dominio globulare e flessibile N-terminale &quot;coda&quot; che sporge al di fuori del nucleosoma. Uno dei principali meccanismi di regolazione della struttura della cromatina e la dinamica si basa su covalenti modificazioni post-traduzionali (PTM), che si verificano principalmente sulla N-terminali degli istoni 3,4. Modificazioni degli istoni possono funzionare alterando la struttura superiore ordine cromatina, cambiando contatti tra istoni-DNA o tra nucleosomi, e controllando così l&#39;accessibilità di DNA-binding proteine ​​(meccanismi cis), o agendo come DockInSiti g di proteine ​​regolatrici, sia come unità singole o incorporati in complessi multimerici. Tali proteine ​​regolatrici possono esercitare la loro funzione in modi diversi: modulando direttamente l&#39;espressione genica (pe proteine ​​TAF), o alterando il posizionamento nucleosoma (cioè cromatina rimodellamento complessi) o modificando altri residui istoni (ad esempio proteine ​​con metil-transferasi o acetil- attività transferasi) (meccanismi trans) 5. L&#39;osservazione che distinto PTM modelli cluster alla specifica loci cromatina portato all&#39;elaborazione della ipotesi che diverse modifiche al sito di distinte possono sinergizzare per generare un codice molecolare mediare lo stato funzionale del DNA sottostante. Il &quot;codice dell&#39;istone ipotesi&quot; ha ottenuto grandi consensi negli anni, ma la sua verifica sperimentale è stata frenata da limiti tecnici 6,7. Proteomica basati su spettrometria di massa (MS) è emerso come unpotente strumento per mappare i modelli modificazione degli istoni e caratterizzare-cromatina proteine ​​che legano 8. MS rileva un cambiamento come Δmass specifico tra la massa sperimentale e teorica di un peptide. A livello di singoli istoni, MS fornisce un metodo imparziale e completa per mappare PTM, consentendo l&#39;individuazione di nuove modifiche e il loro concatenamento rivelando tra loro 9-14. Negli ultimi anni, una serie di strategie sono state sviluppate per sezionare la composizione proteomica di cromatina, compresa la caratterizzazione della intatte cromosomi mitotici 15, l&#39;identificazione di solubili Hptm-binding proteins 16-18 e l&#39;isolamento e l&#39;analisi di specifiche regioni della cromatina (ossia telomeri) 19,20. Tuttavia, l&#39;indagine delle sinergie specifico locus tra PTM degli istoni, le varianti, e proteine ​​della cromatina associate è ancora incompleto. Qui, descriviamo un nuovo approccio, denominato ChroP (CHRO matin P roteomics) 21, che abbiamo sviluppato per caratterizzare in modo efficiente i domini di cromatina funzionalmente distinte. Questo approccio si adatta immunoprecipitazione della cromatina (ChIP), un protocollo ben consolidata utilizzati nella ricerca epigenetica, per l&#39;efficace analisi proteomica basata su MS del campione arricchito. Abbiamo sviluppato due protocolli diversi, a seconda del tipo di cromatina utilizzato come ingresso e la domanda indirizzata da MS; in particolare: 1) circuito integrato di unfixed cromatina nativa digerito con MNase è impiegato per purificare mono-nucleosomi ed a sezionare le hPTMs co-associano (N-ChroP); 2) circuito integrato di cromatina reticolato frammentata mediante sonicazione è usato in combinazione con una strategia basata intergenomica SILAC-caratterizzare tutti co-arricchimento proteine ​​(X-ChroP) vincolante cromatina. Illustriamo qui la combinazione di N-e X-ChroP per l&#39;arricchimento e lo studio eterocromatina, utilizzando H3K9me3 come esca per i passi immunoprecipitazione. L&#39;uso di ChroP può essere estesostudiare sia le regioni distinte su cromatina, o cambiamenti nella composizione della cromatina all&#39;interno della stessa regione durante la transizione a uno stato funzionale diversa, aprendo così la strada a varie applicazioni in epigenetica.

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			<td>Invitrogen&#160;</td>
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			<td height="42" style="height:42px;width:271px;">Iodoacetamide &#8805;99% (HPLC), crystalline</td>
			<td style="width:145px;">Sigma Aldrich</td>
			<td style="width:119px;">I6125</td>
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			<td height="24" style="height:24px;width:271px;">DL-Dithiothreitol</td>
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			<td style="width:119px;">43815</td>
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			<td>Promega</td>
			<td style="width:119px;">V5113</td>
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			<td height="24" style="height:24px;width:271px;">Nanospray OD 360&#956;m x ID 75&#956;m, tips ID 8&#956;m uncoated Pk 5</td>
			<td style="width:145px;">Microcolumn Srl</td>
			<td style="width:119px;">FS360-75-8-N-5-C15</td>
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			<td height="42" style="height:42px;width:271px;">&#160; ReproSil-Pur 120 C18-AQ, 3 &#181;m&#160;&#160; 15 % C</td>
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			<td height="24" style="height:24px;width:271px;">C18 extraction disk, 47 mm</td>
			<td style="width:145px;">Agilent Technologies</td>
			<td style="width:119px;">1&#8203;2&#8203;1&#8203;4&#8203;5&#8203;0&#8203;0&#8203;4</td>
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			<td height="24" style="height:24px;width:271px;">Carbon extraction disk, 47 mm</td>
			<td style="width:145px;">Agilent Technologies</td>
			<td style="width:119px;">12145040</td>
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			<td height="24" style="height:24px;width:271px;">Cation extraction disk</td>
			<td style="width:145px;">Agilent Technologies</td>
			<td style="width:119px;">66889-U</td>
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the chrop approach combines chip and mass spectrometry to dissect locus-specific proteomic landscapes of chromatin

Cromatina è un complesso nucleoproteina altamente dinamico fatto di DNA e proteine ​​che controlla vari processi DNA-dipendente. Struttura della cromatina e la funzione in regioni specifiche è regolato dalla arricchimento locale della istone post-traslazionale modifiche (hPTMs) e varianti, proteine ​​della cromatina vincolanti, compresi fattori di trascrizione, e la metilazione del DNA. La caratterizzazione proteomica di composizione cromatina in corrispondenza di zone funzionali distinti è stata finora ostacolata dalla mancanza di protocolli efficienti per arricchire tali domini alla purezza e quantità appropriata per la successiva analisi approfondita da spettrometria di massa (MS). Descriviamo qui una strategia proteomica cromatina di nuova concezione, denominato ChroP (cromatografia matin P roteomics), per cui un immunoprecipitazione della cromatina preparativa è utilizzato per isolare le regioni della cromatina distinte le cui caratteristiche, in termini di hPTMs, varianti e co-associati proteine ​​non istoniche, sono analizzati da MS. Illustriamo luire la creazione di ChroP per l&#39;arricchimento e l&#39;analisi delle regioni heterochromatic trascrizionalmente silenti, caratterizzato dalla presenza di tri-metilazione della lisina 9 su istone H3. I risultati ottenuti dimostrano il potenziale di ChroP in fondo caratterizzare il proteoma eterocromatina e dimostrare come una strategia analitica potente per comprendere come i determinanti proteici distinti di cromatina interagiscono e sinergizzare stabilire configurazioni strutturali e funzionali specifici locus.

Watch this Scientific Journal Video about The ChroP Approach Combines ChIP and Mass Spectrometry to Dissect Locus-specific Proteomic Landscapes of Chromatin at JoVE.com

The ChroP Approach Combines ChIP and Mass Spectrometry to Dissect Locus-specific Proteomic Landscapes of Chromatin

Combinando nativa e reticolazione cromatina immunoprecipitazione con alta risoluzione di Spettrometria di Massa, l&#39;approccio ChroP permette di sezionare il composito dell&#39;architettura proteomica delle modificazioni degli istoni, le varianti e le proteine ​​non istoniche Synergizing a domini di cromatina funzionalmente distinte.

L&#39;approccio ChroP Combina ChIP e Spettrometria di Massa a sezionare Locus-specifiche proteomica Paesaggi della cromatina

Chromatin is a highly dynamic nucleoprotein complex made of DNA and proteins that controls various DNA-dependent processes. Chromatin structure and ...

the-chrop-approach-combines-chip-mass-spectrometry-to-dissect-locus

Universidad San Sebastian

Research

JoVE Journal

Biology

18.1K Views.  European Institute of Oncology.  Combinando nativa e reticolazione cromatina immunoprecipitazione con alta risoluzione di Spettrometria di Massa, l'approccio ChroP permette di sezionare il composito dell'architettura proteomica delle modificazioni degli istoni, le varianti e le proteine ​​non istoniche Synergizing a domini di cromatina funzionalmente distinte. 

Video: The ChroP Approach Combines ChIP and Mass Spectrometry to Dissect Locus-specific Proteomic Landscapes of Chromatin

MALDI Sample Preparation: the Ultra Thin Layer Method

This video demonstrates the preparation of an ultra-thin matrix/analyte layer for analyzing peptides and proteins by Matrix-Assisted Laser Desorption Ionization Mass Spectrometry (MALDI-MS) 1,2. The ultra-thin layer method involves the production of a substrate layer of matrix crystals (alpha-cyano-4-hydroxycinnamic acid) on the sample plate, which serves as a seeding ground for subsequent crystallization of a matrix/analyte mixture. Advantages of the ultra-thin layer method over other sample deposition approaches (e.g. dried droplet) are that it provides (i) greater tolerance to impurities such as salts and detergents, (ii) better resolution, and (iii) higher spatial uniformity. This method is especially useful for the accurate mass determination of proteins. The protocol was initially developed and optimized for the analysis of membrane proteins and used to successfully analyze ion channels, metabolite transporters, and receptors, containing between 2 and 12 transmembrane domains 2. Since the original publication, it has also shown to be equally useful for the analysis of soluble proteins. Indeed, we have used it for a large number of proteins having a wide range of properties, including those with molecular masses as high as 380 kDa 3. It is currently our method of choice for the molecular mass analysis of all proteins. The described procedure consistently produces high-quality spectra, and it is sensitive, robust, and easy to implement.

This video demonstrates the preparation of an ultra-thin matrix/analyte layer for analyzing peptides and proteins by Matrix-Assisted Laser Desorption Ionization Mass Spectrometry (MALDI-MS).

MALDI Preparazione del campione: il metodo ultra sottile strato

This video demonstrates the preparation of an ultra-thin matrix/analyte layer for analyzing peptides and proteins by Matrix-Assisted Laser Desorption ...

Ricerca

Biologia

Electrophoretic Separation of Proteins

Electrophoresis is used to separate complex mixtures of proteins (e.g., from cells, subcellular fractions, column fractions, or immunoprecipitates), to investigate subunit compositions, and to verify homogeneity of protein samples. It can also serve to purify proteins for use in further applications. In polyacrylamide gel electrophoresis, proteins migrate in response to an electrical field through pores in a polyacrylamide gel matrix; pore size decreases with increasing acrylamide concentration. The combination of pore size and protein charge, size, and shape determines the migration rate of the protein. In this unit, the standard Laemmli method is described for discontinuous gel electrophoresis under denaturing conditions, i.e., in the presence of sodium dodecyl sulfate (SDS). 

In this video, we demonstrate a method for electrophoretic separation of proteins using poly-acrylimide gel electrophoresis (PAGE).

Separazione elettroforetica delle proteine

Electrophoresis is used to separate complex mixtures of proteins (e.g., from cells, subcellular fractions, column fractions, or immunoprecipitates), to ...

A Quantitative Assessment of The Yeast Lipidome using Electrospray Ionization Mass Spectrometry

Lipids are one of the major classes of biomolecules and play important roles membrane dynamics, energy storage, and signalling1-4. The budding yeast Saccharomyces cerevisiae, a genetically and biochemically manipulable unicellular eukaryote with annotated genome and very simple lipidome, is a valuable model for studying biological functions of various lipid species in multicellular eukaryotes2,3,5. S. cerevisiae has 10 major classes of lipids with chain lengths mainly of 16 or 18 carbon atoms and either zero or one degree of unsaturation6,7. Existing methods for lipid identification and quantification - such as high performance liquid chromatography, thin-layer chromatography, fluorescence microscopy, and gas chromatography followed by MS - are well established but have low sensitivity, insufficiently separate various molecular forms of lipids, require lipid derivitization prior to analysis, or can be quite time consuming. Here we present a detailed description of our experimental approach to solve these inherent limitations by using survey-scan ESI/MS for the identification and quantification of the entire complement of lipids in yeast cells. The described method does not require chromatographic separation of complex lipid mixtures recovered from yeast cells, thereby greatly accelerating the process of data acquisition. This method enables lipid identification and quantification at the concentrations as low as g/ml and has been successfully applied to assessing lipidomes of whole yeast cells and their purified organelles. Lipids extraction from whole yeast cells for using this method of lipid analysis takes two to three hours. It takes only five to ten minutes to run each sample of extracted and dried lipids on a Q-TOF mass spectrometer equipped with a nano-electrospray source.

We describe a new quantitative lipidomics method for identifying numerous lipid species in yeast using survey-scan electrospray ionization mass spectrometry (ESI/MS). This method exceeds currently available methods for lipid identification and quantification in the ability to resolve various molecular forms of lipids, sensitivity, and speed.

Una valutazione quantitativa del Lipidome lievito con ionizzazione Electrospray Spettrometria di massa

Lipids are one of the major classes of biomolecules and play important roles membrane dynamics, energy storage, and signalling1-4. The budding yeast ...

Analyzing Large Protein Complexes by Structural Mass Spectrometry

Living cells control and regulate their biological processes through the coordinated action of a large number of proteins that assemble themselves into an array of dynamic, multi-protein complexes1. To gain a mechanistic understanding of the various cellular processes, it is crucial to determine the structure of such protein complexes, and reveal how their structural organization dictates their function. Many aspects of multi-protein complexes are, however, difficult to characterize, due to their heterogeneous nature, asymmetric structure, and dynamics. Therefore, new approaches are required for the study of the tertiary levels of protein organization.
One of the emerging structural biology tools for analyzing macromolecular complexes is mass spectrometry (MS)2-5. This method yields information on the complex protein composition, subunit stoichiometry, and structural topology. The power of MS derives from its high sensitivity and, as a consequence, low sample requirement, which enables examination of protein complexes expressed at endogenous levels. Another advantage is the speed of analysis, which allows monitoring of reactions in real time. Moreover, the technique can simultaneously measure the characteristics of separate populations co-existing in a mixture. 
Here, we describe a detailed protocol for the application of structural MS to the analysis of large protein assemblies. The procedure begins with the preparation of gold-coated capillaries for nanoflow electrospray ionization (nESI). It then continues with sample preparation, emphasizing the buffer conditions which should be compatible with nESI on the one hand, and enable to maintain complexes intact on the other. We then explain, step-by-step, how to optimize the experimental conditions for high mass measurements and acquire MS and tandem MS spectra. Finally, we chart the data processing and analyses that follow. Rather than attempting to characterize every aspect of protein assemblies, this protocol introduces basic MS procedures, enabling the performance of MS and MS/MS experiments on non-covalent complexes. Overall, our goal is to provide researchers unacquainted with the field of structural MS, with knowledge of the principal experimental tools.

Mass spectrometry has proven to be a valuable tool for analyzing large protein complexes. This method enables insights into the composition, stoichiometry and overall architecture of multi-subunit assemblies. Here, we describe, step-by-step, how to perform a structural mass spectrometry analysis, and characterize macromolecular structures.

Analizzando complessi proteici mediante spettrometria di massa di grandi dimensioni strutturali

Living cells control and regulate their biological processes through the coordinated action of a large number of proteins that assemble themselves into an ...

Chromatin Immunoprecipitation (ChIP) using Drosophila tissue

Epigenetics remains a rapidly developing field that studies how the chromatin state contributes to differential gene expression in distinct cell types at different developmental stages. Epigenetic regulation contributes to a broad spectrum of biological processes, including cellular differentiation during embryonic development and homeostasis in adulthood. A critical strategy in epigenetic studies is to examine how various histone modifications and chromatin factors regulate gene expression. To address this, Chromatin Immunoprecipitation (ChIP) is used widely to obtain a snapshot of the association of particular factors with DNA in the cells of interest.
ChIP technique commonly uses cultured cells as starting material, which can be obtained in abundance and homogeneity to generate reproducible data. However, there are several caveats: First, the environment to grow cells in Petri dish is different from that in vivo, thus may not reflect the endogenous chromatin state of cells in a living organism. Second, not all types of cells can be cultured ex vivo. There are only a limited number of cell lines, from which people can obtain enough material for ChIP assay.
Here we describe a method to do ChIP experiment using Drosophila tissues. The starting material is dissected tissue from a living animal, thus can accurately reflect the endogenous chromatin state. The adaptability of this method with many different types of tissue will allow researchers to address a lot more biologically relevant questions regarding epigenetic regulation in vivo1, 2. Combining this method with high-throughput sequencing (ChIP-seq) will further allow researchers to obtain an epigenomic landscape.

Chromatin Immunoprecipitation ChIP using Drosophila tissue

Recently high-throughput sequencing technology has greatly increased sensitivity of Chromatin Immunoprecipitation (ChIP) experiment and prompted its application using purified cells or dissected tissue. Here we delineate a method to use ChIP technique with Drosophila tissue, which can address the endogenous chromatin state in a well-characterized biological system.

Immunoprecipitazione della cromatina (ChIP) con Drosophila Tessuto

Epigenetics remains a rapidly developing field that studies how the chromatin state contributes to differential gene expression in distinct cell types at ...

A New Approach for the Comparative Analysis of Multiprotein Complexes Based on 15N Metabolic Labeling and Quantitative Mass Spectrometry

The introduced protocol provides a tool for the analysis of multiprotein complexes in the thylakoid membrane, by revealing insights into complex composition under different conditions. In this protocol the approach is demonstrated by comparing the composition of the protein complex responsible for cyclic electron flow (CEF) in Chlamydomonas reinhardtii, isolated from genetically different strains. The procedure comprises the isolation of thylakoid membranes, followed by their separation into multiprotein complexes by sucrose density gradient centrifugation, SDS-PAGE, immunodetection and comparative, quantitative mass spectrometry (MS) based on differential metabolic labeling (14N/15N) of the analyzed strains. Detergent solubilized thylakoid membranes are loaded on sucrose density gradients at equal chlorophyll concentration. After ultracentrifugation, the gradients are separated into fractions, which are analyzed by mass-spectrometry based on equal volume. This approach allows the investigation of the composition within the gradient fractions and moreover to analyze the migration behavior of different proteins, especially focusing on ANR1, CAS, and PGRL1. Furthermore, this method is demonstrated by confirming the results with immunoblotting and additionally by supporting the findings from previous studies (the identification and PSI-dependent migration of proteins that were previously described to be part of the CEF-supercomplex such as PGRL1, FNR, and cyt f). Notably, this approach is applicable to address a broad range of questions for which this protocol can be adopted and e.g. used for comparative analyses of multiprotein complex composition isolated from distinct environmental conditions.

A New Approach for the Comparative Analysis of Multiprotein Complexes Based on 15N Metabolic Labeling and Quantitative Mass Spectrometry

The described comparative, quantitative proteomic approach aims at obtaining insights into the composition of multiprotein complexes&#160;under different conditions and is demonstrated by comparing genetically different strains. For quantitative analysis equal volumes of different fractions from a sucrose density gradient are mixed and analyzed by mass spectrometry.

Un nuovo approccio per l&#39;analisi comparativa dei multiproteico Complessi Basato su<sup&gt; 15</sup&gt; N metabolica Etichettatura e quantitativa Spettrometria di Massa

The introduced protocol provides a tool for the analysis of multiprotein complexes in the thylakoid membrane, by revealing insights into complex ...

Capture Compound Mass Spectrometry - A Powerful Tool to Identify Novel c-di-GMP Effector Proteins

Considerable progress has been made during the last decade towards the identification and characterization of enzymes involved in the synthesis (diguanylate cyclases) and degradation (phosphodiesterases) of the second messenger c-di-GMP. In contrast, little information is available regarding the molecular mechanisms and cellular components through which this signaling molecule regulates a diverse range of cellular processes. Most of the known effector proteins belong to the PilZ family or are degenerated diguanylate cyclases or phosphodiesterases that have given up on catalysis and have adopted effector function. Thus, to better define the cellular c-di-GMP network in a wide range of bacteria experimental methods are required to identify and validate novel effectors for which reliable in silico predictions fail.
We have recently developed a novel Capture Compound Mass Spectrometry (CCMS) based technology as a powerful tool to biochemically identify and characterize c-di-GMP binding proteins. This technique has previously been reported to be applicable to a wide range of organisms1. Here we give a detailed description of the protocol that we utilize to probe such signaling components. As an example, we use Pseudomonas aeruginosa, an opportunistic pathogen in which c-di-GMP plays a critical role in virulence and biofilm control. CCMS identified 74% (38/51) of the known or predicted components of the c-di-GMP network. This study explains the CCMS procedure in detail, and establishes it as a powerful and versatile tool to identify novel components involved in small molecule signaling.

The ubiquitous second messenger c-di-GMP controls growth and behavior of many bacteria. We have developed a novel Capture Compound Mass Spectrometry based technology to biochemically identify and characterize c-di-GMP binding proteins in virtually any bacterial species.

Capture spettrometria di massa Compound - un potente strumento per identificare nuovi c-di-GMP effettori Proteine

Considerable progress has been made during the last decade towards the identification and characterization of enzymes involved in the synthesis ...

Selected Reaction Monitoring Mass Spectrometry for Absolute Protein Quantification

Absolute quantification of target proteins within complex biological samples is critical to a wide range of research and clinical applications. This protocol provides step-by-step instructions for the development and application of quantitative assays using selected reaction monitoring (SRM) mass spectrometry (MS). First, likely quantotypic target peptides are identified based on numerous criteria. This includes identifying proteotypic peptides, avoiding sites of posttranslational modification, and analyzing the uniqueness of the target peptide to the target protein. Next, crude external peptide standards are synthesized and used to develop SRM assays, and the resulting assays are used to perform qualitative analyses of the biological samples. Finally, purified, quantified, heavy isotope labeled internal peptide standards are prepared and used to perform isotope dilution series SRM assays. Analysis of all of the resulting MS data is presented. This protocol was used to accurately assay the absolute abundance of proteins of the chemotaxis signaling pathway within RAW 264.7 cells (a mouse monocyte/macrophage cell line). The quantification of Gi2 (a heterotrimeric G-protein &#945;-subunit) is described in detail.

This protocol describes how to perform absolute quantification assays of target proteins within complex biological samples using selected reaction monitoring. It was used to accurately quantify proteins of the mouse macrophage chemotaxis signaling pathway. Target peptide selection, assay development, and qualitative and quantitative assays are described in detail.

Reazione selezionato Monitoraggio spettrometria di massa per Absolute Protein Quantificazione

Absolute quantification of target proteins within complex biological samples is critical to a wide range of research and clinical applications. This ...

Amplification, Next-generation Sequencing, and Genomic DNA Mapping of Retroviral Integration Sites

Retroviruses exhibit signature integration preferences on both the local and global scales. Here, we present a detailed protocol for (1) generation of diverse libraries of retroviral integration sites using ligation-mediated PCR (LM-PCR) amplification and next-generation sequencing (NGS), (2) mapping the genomic location of each virus-host junction using BEDTools, and (3) analyzing the data for statistical relevance. Genomic DNA extracted from infected cells is fragmented by digestion with restriction enzymes or by sonication. After suitable DNA end-repair, double-stranded linkers are ligated onto the DNA ends, and semi-nested PCR is conducted using primers complementary to both the long terminal repeat (LTR) end of the virus and the ligated linker DNA. The PCR primers carry sequences required for DNA clustering during NGS, negating the requirement for separate adapter ligation. Quality control (QC) is conducted to assess DNA fragment size distribution and adapter DNA incorporation prior to NGS. Sequence output files are filtered for LTR-containing reads, and the sequences defining the LTR and the linker are cropped away. Trimmed host cell sequences are mapped to a reference genome using BLAT and are filtered for minimally 97% identity to a unique point in the reference genome. Unique integration sites are scrutinized for adjacent nucleotide (nt) sequence and distribution relative to various genomic features. Using this protocol, integration site libraries of high complexity can be constructed from genomic DNA in three days. The entire protocol that encompasses exogenous viral infection of susceptible tissue culture cells to integration site analysis can therefore be conducted in approximately one to two weeks. Recent applications of this technology pertain to longitudinal analysis of integration sites from HIV-infected patients.

We describe a protocol for amplifying retroviral integration sites from the genomic DNA of infected cells, sequencing the amplified virus-host junctions, and then mapping these sequences to a reference genome. We also describe techniques to quantify the distribution of integration sites relative to various genomic annotations using BEDTools.

Amplificazione, sequenziamento di prossima generazione, e DNA genomico mappatura dei siti di integrazione retrovirali

Retroviruses exhibit signature integration preferences on both the local and global scales. Here, we present a detailed protocol for (1) generation of ...

Applications of the Single-probe: Mass Spectrometry Imaging and Single Cell Analysis under Ambient Conditions

Mass spectrometry imaging (MSI) and in-situ single cell mass spectrometry (SCMS) analysis under ambient conditions are two emerging fields with great potential for the detailed mass spectrometry (MS) analysis of biomolecules from biological samples. The single-probe, a miniaturized device with integrated sampling and ionization capabilities, is capable of performing both ambient MSI and in-situ SCMS analysis. For ambient MSI, the single-probe uses surface micro-extraction to continually conduct MS analysis of the sample, and this technique allows the creation of MS images with high spatial resolution (8.5 &#181;m) from biological samples such as mouse brain and kidney sections. Ambient MSI has the advantage that little to no sample preparation is needed before the analysis, which reduces the amount of potential artifacts present in data acquisition and allows a more representative analysis of the sample to be acquired. For in-situ SCMS, the single-probe tip can be directly inserted into live eukaryotic cells such as HeLa cells, due to the small sampling tip size (&lt; 10 &#181;m), and this technique is capable of detecting a wide range of metabolites inside individual cells at near real-time. SCMS enables a greater sensitivity and accuracy of chemical information to be acquired at the single cell level, which could improve our understanding of biological processes at a more fundamental level than previously possible. The single-probe device can be potentially coupled with a variety of mass spectrometers for broad ranges of MSI and SCMS studies.

Here, we present protocols to perform both ambient mass spectrometry imaging (MSI) of tissues and in-situ live single cell MS (SCMS) analysis using the single-probe, which is a miniaturized multifunctional device for MS analysis.

Applicazioni del singolo-probe: Mass Spectrometry Imaging e analisi singola cella in condizioni ambientali

Mass spectrometry imaging (MSI) and in-situ single cell mass spectrometry (SCMS) analysis under ambient conditions are two emerging fields with great ...