עבודה זו נתמכה על ידי 115347-RSG-08-271-01-GMC מ-ACS, ועל ידי CA138631 מענק מ-NIH.

<ol>
	<li>Wang, G. G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Haematopoietic+malignancies+caused+by+dysregulation+of+a+chromatin-binding+PHD+finger.">Haematopoietic malignancies caused by dysregulation of a chromatin-binding PHD finger.</a> Nature. 459 (7248), (2009).</li><li>Benevolenskaya, E. V. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Binding+of+pRB+to+the+PHD+protein+RBP2+promotes+cellular+differentiation.">Binding of pRB to the PHD protein RBP2 promotes cellular differentiation.</a> Mol Cell. 18 (6), 623-623 (2005).</li><li>Lopez-Bigas, N. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Genome-wide+analysis+of+the+H3K4+histone+demethylase+RBP2+reveals+a+transcriptional+program+controlling+differentiation.">Genome-wide analysis of the H3K4 histone demethylase RBP2 reveals a transcriptional program controlling differentiation.</a> Mol Cell. 31 (4), 520-520 (2008).</li><li>Benevolenskaya, E. V. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Histone+H3K4+demethylases+are+essential+in+development+and+differentiation.">Histone H3K4 demethylases are essential in development and differentiation.</a> Biochem Cell Biol. 85 (4), 435-435 (2007).</li><li>Odom, D. T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Control+of+pancreas+and+liver+gene+expression+by+HNF+transcription+factors.">Control of pancreas and liver gene expression by HNF transcription factors.</a> Science. 303 (5662), 1378-1378 (2004).</li><li>Guenther, M. G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Aberrant+chromatin+at+genes+encoding+stem+cell+regulators+in+human+mixed-lineage+leukemia.">Aberrant chromatin at genes encoding stem cell regulators in human mixed-lineage leukemia.</a> Genes Dev. 22 (24), 3403-3403 (2008).</li></ol>

אין ניגודי אינטרסים הכריז.

הבדלים פונקציונליים בין RBP2 isoforms טרם נקבעו. השתמשנו גישה מקיפה כדי לזהות אזורים גנומית מחויב RBP2 isoforms ולהגדיר את הקטגוריות פונקציונלי כי אזורים אלה מייצגים. זה בוצע על ידי ניתוח שבב Seq ואחריו ניתוח ביואינפורמטיקה רצף המתקבל קורא. RBP2 משנה שאריות ליזין מפוגל על ​​זנבות היסטון. מצאנו כי RBP2 איזופורם גדול המכיל את מודול הכרה איזופורם היסטון מפוגל קטן RBP2 ליזין שחסר זה לאגד המודול אזורים שונים בגנום האנושי (איור 5 א). חשוב לציין, איזופורם ספציפי אזורים אזורים חופפים שייכים גנים עם פונקציות מולקולריים שונים (איור 5 ב). לדוגמה, &quot;הכרומטין מחייב&quot; או &quot;גורם שעתוק מחייבים&quot; פונקציות ניתן לייחס מטרות הגן של איזופורם RBP2 קטן אך לא RBP2 איזופורם גדול (איור 5 ב). על ידי השוואת הגן בפועל קובע שנוצר עבור כל isoforms ו RBP2 איזופורם גדול (מידע לא מוצג), אנחנו יכולים גם להגדיר אם איזופורם גדול הוא גויס במיוחד כדי גנים מסוימים.

רצפים oligonucleotide 2006 Illumina, Inc כל הזכויות שמורות. <ul style=";text-align:right;direction:rtl"><li style=";text-align:right;direction:rtl"> Sol_PCR_1 רצף 5&#39;-AAT גת ACG מהפקולטה לרוקחות אוכלים ACC ACC GAG ATC TAC ACT CTT TCC CTA CAC GAC GCT CTT CCG ATC-T-3 &quot; </li><li style=";text-align:right;direction:rtl"> Sol_PCR_2 רצף 5&#39;-CAA GCA GAA GAC GGC ATA CGA GCT CTT CCG ATC-T-3 &quot; </li></ul>

genome-wide analysis using chip to identify isoform-specific gene targets

גיוס גורמים תעתיק ו epigenetic אל המטרות שלהם היא צעד מפתח בוויסות שלהם. בהשתתפות בולטת בגיוס הם תחומים חלבון אשר נקלטות על ידי שינויים היסטון ספציפיים. תחום אחד כזה הוא homeodomain צמח (PhD), נמצא הכרומטין מחייב כמה חלבונים. RBP2 גורם epigenetic יש מספר תחומים PHD, לעומת זאת, יש להם פונקציות שונות (איור 4). בפרט, בטרמינל C-PHD תחום, נמצא היתוך RBP2 בשעור של לוקמיה אדם, נקשר trimethylated ליזין 4 ב H3 היסטון (H3K4me3) 1. תמליל המתאים איזופורם RBP2 המכיל את בטרמינל C-PHD מצטבר במהלך של בידול promonocytic, לימפומה הנגזרות, U937 תאים לתוך מונוציטים 2. בקנה אחד עם שתי קבוצות של נתונים, הגנום כולו ניתוח הראה כי התמיינות תאים U937, החלבון RBP2 מקבל מקומי לאזורים גנומית מועשר עבור H3K4me3 3. לוקליזציה של RBP2 ביעדים שלה בקורלציה עם ירידה H3K4me3 עקב פעילות RBP2 demethylase היסטון וירידה פעילות תעתיק. לעומת זאת, שני PhDs אחרים RBP2 אינם מסוגלים להיקשר H3K4me3. יש לציין כי C-PHD של הטרמינל תחום RBP2 נעדרת RBP2 קטן איזופורם 4. זה מתקבל על הדעת כי איזופורם קטן RBP2, שאין לה אינטראקציה עם H3K4me3, שונה איזופורם גדול במיקום הגנומי. ההבדל במיקום הגנומי של RBP2 isoforms עשוי להסביר המגוון שנצפתה פונקציה RBP2. באופן ספציפי, RBP2 הוא שחקן קריטי בידול הסלולר בתיווך החלבון רטינובלסטומה (PRB). בהתאם לנתונים אלה, ניתוח הקודמת הגנום כולו, ללא הבחנה בין isoforms, זיהו שתי קבוצות נפרדות של RBP2 גני מטרה: 1) גנים מחויב RBP2 באופן שאינו תלוי בידול; 2) הגנים מחויב RBP2 תוך בידול תלוי בצורה. כדי לזהות הבדלים בין לוקליזציה isoforms הופענו הגנום כולו ניתוח על ידי מיקום Seq שבב. שימוש בנוגדנים המזהים הן RBP2 isoforms לנו ממוקמת כל RBP2 מטרות. בנוסף יש לנו רק לקשור נוגדנים גדול, לא קטן RBP2 איזופורם (איור 4). לאחר זיהוי מטרות איזופורם גדול, אפשר ואז להחסיר אותם מכל RBP2 מטרות כדי לחשוף את מטרות איזופורם קטן. נתונים אלו מראים את התרומה של תחום הכרומטין-אינטראקציה בגיוס חלבון אתרי הקישור שלו בגנום.

Watch this Scientific Journal Video about Genome-wide Analysis using ChIP to Identify Isoform-specific Gene Targets at JoVE.com

Genome-wide Analysis using ChIP to Identify Isoform-specific Gene Targets

כאן אנו מציגים immunoprecipitation הכרומטין (שבב) נוהל לניתוח הגנום כולו מיקום isoforms חלבונים שונים בתחום היסטון מחייב. אנו מיישמים אותו לניתוח שבב Seq לזהות מטרות demethylase היסטון KDM5A/JARID1A/RBP2.

הגנום כולו ניתוח באמצעות שבב זיהוי איזופורם ספציפי מטרות ג&#39;ין

Recruitment of transcriptional and epigenetic factors to their targets is a key step in their regulation. Prominently featured in recruitment are the ...

genome-wide-analysis-using-chip-to-identify-isoform-specific-gene

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14.4K Views.  University of Illinois Chicago - UIC. כאן אנו מציגים immunoprecipitation הכרומטין (שבב) נוהל לניתוח הגנום כולו מיקום isoforms חלבונים שונים בתחום היסטון מחייב. אנו מיישמים אותו לניתוח שבב Seq לזהות מטרות demethylase היסטון KDM5A/JARID1A/RBP2.

Video: Genome-wide Analysis using ChIP to Identify Isoform-specific Gene Targets

Bacterial Gene Expression Analysis Using Microarrays

Gene Expression חיידקית ניתוח שימוש microarrays

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

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

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

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

הגנום כולו ניתוח (טעינה) רמות Aminoacylation של tRNA שימוש microarrays

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

Genome-wide Screen for miRNA Targets Using the MISSION Target ID Library

The Target ID Library is designed to assist in discovery and identification of microRNA (miRNA) targets. The Target ID Library is a plasmid-based, genome-wide cDNA library cloned into the 3'UTR downstream from the dual-selection fusion protein, thymidine kinase-zeocin (TKzeo). The first round of selection is for stable transformants, followed with introduction of a miRNA of interest, and finally, selecting for cDNAs containing the miRNA's target. Selected cDNAs are identified by sequencing (see Figure 1-3 for Target ID Library Workflow and details).
To ensure broad coverage of the human transcriptome, Target ID Library cDNAs were generated via oligo-dT priming using a pool of total RNA prepared from multiple human tissues and cell lines. Resulting cDNA range from 0.5 to 4 kb, with an average size of 1.2 kb, and were cloned into the p3&#900;TKzeo dual-selection plasmid (see Figure 4 for plasmid map). The gene targets represented in the library can be found on the Sigma-Aldrich webpage. Results from Illumina sequencing (Table 3), show that the library includes 16,922 of the 21,518 unique genes in UCSC RefGene (79%), or 14,000 genes with 10 or more reads (66%).

The Target ID Library is a plasmid-based, genome-wide collection of cloned cDNA used to identify miRNA targets. Here we demonstrate its use and application.

הגנום כולו מסך עבור מטרות מירנה שימוש יעד המשימה ספריית מזהה

The Target ID Library is designed to assist in discovery and identification of microRNA (miRNA) targets. The Target ID Library is a plasmid-based, ...

Quantitative and Automated High-throughput Genome-wide RNAi Screens in C. elegans

RNA interference is a powerful method to understand gene function, especially when conducted at a whole-genome scale and in a quantitative context. In C. elegans, gene function can be knocked down simply and efficiently by feeding worms with bacteria expressing a dsRNA corresponding to a specific gene 1. While the creation of libraries of RNAi clones covering most of the C. elegans genome 2,3 opened the way for true functional genomic studies (see for example 4-7), most established methods are laborious. Moy and colleagues have developed semi-automated protocols that facilitate genome-wide screens 8. The approach relies on microscopic imaging and image analysis. 
	Here we describe an alternative protocol for a high-throughput genome-wide screen, based on robotic handling of bacterial RNAi clones, quantitative analysis using the COPAS Biosort (Union Biometrica (UBI)), and an integrated software: the MBioLIMS (Laboratory Information Management System from Modul-Bio) a technology that provides increased throughput for data management and sample tracking. The method allows screens to be conducted on solid medium plates. This is particularly important for some studies, such as those addressing host-pathogen interactions in C. elegans, since certain microbes do not efficiently infect worms in liquid culture.
	We show how the method can be used to quantify the importance of genes in anti-fungal innate immunity in C. elegans. In this case, the approach relies on the use of a transgenic strain carrying an epidermal infection-inducible fluorescent reporter gene, with GFP under the control of the promoter of the antimicrobial peptide gene nlp 29 and a red fluorescent reporter that is expressed constitutively in the epidermis. The latter provides an internal control for the functional integrity of the epidermis and nonspecific transgene silencing9. When control worms are infected by the fungus they fluoresce green. Knocking down by RNAi a gene required for nlp 29 expression results in diminished fluorescence after infection. Currently, this protocol allows more than 3,000 RNAi clones to be tested and analyzed per week, opening the possibility of screening the entire genome in less than 2 months.

Quantitative and Automated High-throughput Genome-wide RNAi Screens in C. elegans

We describe a protocol using C. elegans and RNAi feeding libraries that allows automated measurement of multiple parameters such as fluorescence, size and opacity of individual worms in a population. We give one example of a screen to identify genes involved in anti-fungal innate immunity in C. elegans.

כמותיים אוטומטי תפוקה גבוהה הגנום כולו RNAi המסכים ג elegans</em

RNA interference is a powerful method to understand gene function, especially when conducted at a whole-genome scale and in a quantitative context. In C. ...

Isolation of Ribosome Bound Nascent Polypeptides in vitro to Identify Translational Pause Sites Along mRNA

The rate of translational elongation is non-uniform. mRNA secondary structure, codon usage and mRNA associated proteins may alter ribosome movement on the messagefor review see 1. However, it's now widely accepted that synonymous codon usage is the primary cause of non-uniform translational elongation rates1. Synonymous codons are not used with identical frequency. A bias exists in the use of synonymous codons with some codons used more frequently than others2. Codon bias is organism as well as tissue specific2,3. Moreover, frequency of codon usage is directly proportional to the concentrations of cognate tRNAs4. Thus, a frequently used codon will have higher multitude of corresponding tRNAs, which further implies that a frequent codon will be translated faster than an infrequent one. Thus, regions on mRNA enriched in rare codons (potential pause sites) will as a rule slow down ribosome movement on the message and cause accumulation of nascent peptides of the respective sizes5-8. These pause sites can have functional impact on the protein expression, mRNA stability and protein foldingfor review see 9. Indeed, it was shown that alleviation of such pause sites can alter ribosome movement on mRNA and subsequently may affect the efficiency of co-translational (in vivo) protein folding1,7,10,11. To understand the process of protein folding in vivo, in the cell, that is ultimately coupled to the process of protein synthesis it is essential to gain comprehensive insights into the impact of codon usage/tRNA content on the movement of ribosomes along mRNA during translational elongation.
Here we describe a simple technique that can be used to locate major translation pause sites for a given mRNA translated in various cell-free systems6-8. This procedure is based on isolation of nascent polypeptides accumulating on ribosomes during in vitro translation of a target mRNA. The rationale is that at low-frequency codons, the increase in the residence time of the ribosomes results in increased amounts of nascent peptides of the corresponding sizes. In vitro transcribed mRNA is used for in vitro translational reactions in the presence of radioactively labeled amino acids to allow the detection of the nascent chains. In order to isolate ribosome bound nascent polypeptide complexes the translation reaction is layered on top of 30% glycerol solution followed by centrifugation. Nascent polypeptides in polysomal pellet are further treated with ribonuclease A and resolved by SDS PAGE. This technique can be potentially used for any protein and allows analysis of ribosome movement along mRNA and the detection of the major pause sites. Additionally, this protocol can be adapted to study factors and conditions that can alter ribosome movement and thus potentially can also alter the function/conformation of the protein.

Isolation of Ribosome Bound Nascent Polypeptides in vitro to Identify Translational Pause Sites Along mRNA

A technique to identify translational pause sites on mRNA is described. This procedure is based on isolation of nascent polypeptides accumulating on ribosomes during in vitro translation of a target mRNA, followed by the size analysis of the nascent chains using a denaturing gel electrophoresis.

הבידוד של הריבוזום פוליפפטידים המתהווה כרוכים<em&gt; במבחנה</em&gt; כדי לזהות אתרים השהה של תרגום לאורך ה-mRNA

The rate of translational elongation is non-uniform. mRNA secondary structure, codon usage and mRNA associated proteins may alter ribosome movement on the ...

A Novel Bayesian Change-point Algorithm for Genome-wide Analysis of Diverse ChIPseq Data Types

ChIPseq is a widely used technique for investigating protein-DNA interactions. Read density profiles are generated by using next-sequencing of protein-bound DNA and aligning the short reads to a reference genome. Enriched regions are revealed as peaks, which often differ dramatically in shape, depending on the target protein1. For example, transcription factors often bind in a site- and sequence-specific manner and tend to produce punctate peaks, while histone modifications are more pervasive and are characterized by broad, diffuse islands of enrichment2. Reliably identifying these regions was the focus of our work.
Algorithms for analyzing ChIPseq data have employed various methodologies, from heuristics3-5 to more rigorous statistical models, e.g. Hidden Markov Models (HMMs)6-8. We sought a solution that minimized the necessity for difficult-to-define, ad hoc parameters that often compromise resolution and lessen the intuitive usability of the tool. With respect to HMM-based methods, we aimed to curtail parameter estimation procedures and simple, finite state classifications that are often utilized.
Additionally, conventional ChIPseq data analysis involves categorization of the expected read density profiles as either punctate or diffuse followed by subsequent application of the appropriate tool. We further aimed to replace the need for these two distinct models with a single, more versatile model, which can capably address the entire spectrum of data types.
To meet these objectives, we first constructed a statistical framework that naturally modeled ChIPseq data structures using a cutting edge advance in HMMs9, which utilizes only explicit formulas-an innovation crucial to its performance advantages. More sophisticated then heuristic models, our HMM accommodates infinite hidden states through a Bayesian model. We applied it to identifying reasonable change points in read density, which further define segments of enrichment. Our analysis revealed how our Bayesian Change Point (BCP) algorithm had a reduced computational complexity-evidenced by an abridged run time and memory footprint. The BCP algorithm was successfully applied to both punctate peak and diffuse island identification with robust accuracy and limited user-defined parameters. This illustrated both its versatility and ease of use. Consequently, we believe it can be implemented readily across broad ranges of data types and end users in a manner that is easily compared and contrasted, making it a great tool for ChIPseq data analysis that can aid in collaboration and corroboration between research groups. Here, we demonstrate the application of BCP to existing transcription factor10,11 and epigenetic data12 to illustrate its usefulness.

Our Bayesian Change Point (BCP) algorithm builds on state-of-the-art advances in modeling change-points via Hidden Markov Models and applies them to chromatin immunoprecipitation sequencing (ChIPseq) data analysis. BCP performs well in both broad and punctate data types, but excels in accurately identifying robust, reproducible islands of diffuse histone enrichment.

אלגוריתם רומן ייס שינוי נקודות לניתוח הגנום רחב, של סוגי נתוני ChIPseq מגוונים

ChIPseq is a widely used technique for investigating protein-DNA interactions. Read density profiles are generated by using next-sequencing of ...

Genome-wide Gene Deletions in Streptococcus sanguinis by High Throughput PCR

Transposon mutagenesis and single-gene deletion are two methods applied in genome-wide gene knockout in bacteria 1,2. Although transposon mutagenesis is less time consuming, less costly, and does not require completed genome information, there are two weaknesses in this method: (1) the possibility of a disparate mutants in the mixed mutant library that counter-selects mutants with decreased competition; and (2) the possibility of partial gene inactivation whereby genes do not entirely lose their function following the insertion of a transposon. Single-gene deletion analysis may compensate for the drawbacks associated with transposon mutagenesis. To improve the efficiency of genome-wide single gene deletion, we attempt to establish a high-throughput technique for genome-wide single gene deletion using Streptococcus sanguinis as a model organism. Each gene deletion construct in S. sanguinis genome is designed to comprise 1-kb upstream of the targeted gene, the aphA-3 gene, encoding kanamycin resistance protein, and 1-kb downstream of the targeted gene. Three sets of primers F1/R1, F2/R2, and F3/R3, respectively, are designed and synthesized in a 96-well plate format for PCR-amplifications of those three components of each deletion construct. Primers R1 and F3 contain 25-bp sequences that are complementary to regions of the aphA-3 gene at their 5' end. A large scale PCR amplification of the aphA-3 gene is performed once for creating all single-gene deletion constructs. The promoter of aphA-3 gene is initially excluded to minimize the potential polar effect of kanamycin cassette. To create the gene deletion constructs, high-throughput PCR amplification and purification are performed in a 96-well plate format. A linear recombinant PCR amplicon for each gene deletion will be made up through four PCR reactions using high-fidelity DNA polymerase. The initial exponential growth phase of S. sanguinis cultured in Todd Hewitt broth supplemented with 2.5% inactivated horse serum is used to increase competence for the transformation of PCR-recombinant constructs. Under this condition, up to 20% of S. sanguinis cells can be transformed using ~50 ng of DNA. Based on this approach, 2,048 mutants with single-gene deletion were ultimately obtained from the 2,270 genes in S. sanguinis excluding four gene ORFs contained entirely within other ORFs in S. sanguinis SK36 and 218 potential essential genes. The technique on creating gene deletion constructs is high throughput and could be easy to use in genome-wide single gene deletions for any transformable bacteria.

Genome-wide Gene Deletions in Streptococcus sanguinis by High Throughput PCR

An efficient genome-wide single gene mutation method has been established using Streptococcus sanguinis as a model organism. This method has achieved via high throughput recombinant PCRs and transformations.

מחיקות Gene הגנום ב<em&gt; סטרפטוקוקוס sanguinis</em&gt; על ידי תפוקה הגבוהה PCR

Transposon  mutagenesis and single-gene deletion are two methods applied in genome-wide  gene knockout in bacteria 1,2. Although transposon mutagenesis is ...

Polysome Fractionation and Analysis of Mammalian Translatomes on a Genome-wide Scale

mRNA translation plays a central role in the regulation of gene expression and represents the most energy consuming process in mammalian cells. Accordingly, dysregulation of mRNA translation is considered to play a major role in a variety of pathological states including cancer. Ribosomes also host chaperones, which facilitate folding of nascent polypeptides, thereby modulating function and stability of newly synthesized polypeptides. In addition, emerging data indicate that ribosomes serve as a platform for a repertoire of signaling molecules, which are implicated in a variety of post-translational modifications of newly synthesized polypeptides as they emerge from the ribosome, and/or components of translational machinery. Herein, a well-established method of ribosome fractionation using sucrose density gradient centrifugation is described. In conjunction with the in-house developed &#8220;anota&#8221; algorithm this method allows direct determination of differential translation of individual mRNAs on a genome-wide scale. Moreover, this versatile protocol can be used for a variety of biochemical studies aiming to dissect the function of ribosome-associated protein complexes, including those that play a central role in folding and degradation of newly synthesized polypeptides.

Ribosomes play a central role in protein synthesis. Polyribosome (polysome) fractionation by sucrose density gradient centrifugation allows direct determination of translation efficiencies of individual mRNAs on a genome-wide scale. In addition, this method can be used for biochemical analysis of ribosome- and polysome-associated factors such as chaperones and signaling molecules.

Polysome היפוך חלוק וניתוח של יונקי Translatomes בקנה מידת הגנום

mRNA translation plays a central role in the regulation of gene expression and represents the most energy consuming process in mammalian cells. ...

DNA-affinity-purified Chip (DAP-chip) Method to Determine Gene Targets for Bacterial Two component Regulatory Systems

In vivo methods such as ChIP-chip are well-established techniques used to determine global gene targets for transcription factors. However, they are of limited use in exploring bacterial two component regulatory systems with uncharacterized activation conditions. Such systems regulate transcription only when activated in the presence of unique signals. Since these signals are often unknown, the in vitro microarray based method described in this video article can be used to determine gene targets and binding sites for response regulators. This DNA-affinity-purified-chip method may be used for any purified regulator in any organism with a sequenced genome. The protocol involves allowing the purified tagged protein to bind to sheared genomic DNA and then affinity purifying the protein-bound DNA, followed by fluorescent labeling of the DNA and hybridization to a custom tiling array. Preceding steps that may be used to optimize the assay for specific regulators are also described. The peaks generated by the array data analysis are used to predict binding site motifs, which are then experimentally validated. The motif predictions can be further used to determine gene targets of orthologous response regulators in closely related species. We demonstrate the applicability of this method by determining the gene targets and binding site motifs and thus predicting the function for a sigma54-dependent response regulator DVU3023 in the environmental bacterium Desulfovibrio vulgaris Hildenborough.

DNA-affinity-purified Chip DAP-chip Method to Determine Gene Targets for Bacterial Two component Regulatory Systems

This video article describes an in vitro microarray based method to determine the gene targets and binding sites for two component system response regulators.

שיטת צ&#39;יפ (DAP-שבב) מטוהרת-DNA-זיקה לקביעת מטרות גן לחיידקית שתי מערכות רגולטוריות רכיב

In vivo methods such as ChIP-chip are well-established techniques used to determine global gene targets for transcription factors. However, they are of ...

Genome-wide Mapping of Drug-DNA Interactions in Cells with COSMIC (Crosslinking of Small Molecules to Isolate Chromatin)

The genome is the target of some of the most effective chemotherapeutics, but most of these drugs lack DNA sequence specificity, which leads to dose-limiting toxicity and many adverse side effects. Targeting the genome with sequence-specific small molecules may enable molecules with increased therapeutic index and fewer off-target effects. N-methylpyrrole/N-methylimidazole polyamides are molecules that can be rationally designed to target specific DNA sequences with exquisite precision. And unlike most natural transcription factors, polyamides can bind to methylated and chromatinized DNA without a loss in affinity. The sequence specificity of polyamides has been extensively studied in vitro with cognate site identification (CSI) and with traditional biochemical and biophysical approaches, but the study of polyamide binding to genomic targets in cells remains elusive. Here we report a method, the crosslinking of small molecules to isolate chromatin (COSMIC), that identifies polyamide binding sites across the genome. COSMIC is similar to chromatin immunoprecipitation (ChIP), but differs in two important ways: (1) a photocrosslinker is employed to enable selective, temporally-controlled capture of polyamide binding events, and (2) the biotin affinity handle is used to purify polyamide&#8211;DNA conjugates under semi-denaturing conditions to decrease DNA that is non-covalently bound. COSMIC is a general strategy that can be used to reveal the genome-wide binding events of polyamides and other genome-targeting chemotherapeutic agents.

Genome-wide Mapping of Drug-DNA Interactions in Cells with COSMIC Crosslinking of Small Molecules to Isolate Chromatin

Identifying the direct targets of genome-targeting molecules remains a major challenge. To understand how DNA-binding molecules engage the genome, we developed a method that relies on crosslinking of small molecules to isolate chromatin (COSMIC).