Biz transmisyon elektron mikroskobu için yardım Stephan Wilkens teşekkür ederim. Bu çalışma Sağlık Hibe R01AG023731 Ulusal Enstitüleri tarafından desteklenmiştir.

Önceki çalışmalar Mgm101 ilk amino terminal kalıntıları 22 mitokondri 19 içine aldıktan sonra yarıldığı gösterilmiştir. Escherichia coli içinde ekspresyonu için, ilk 22 kodonları eksik MGM101 açık okuma çerçevesi PCR ile amplifiye edilir ve ekspresyon vektörü üretilmesinde ise pMAL-C2E değiştirilmiş bir versiyonu maltoz bağlayıcı protein (MBP) kodlayan bir erkek sekansının aşağı yerleştirilir. Bu PreScission proteaz (Şekil 3), bir ayrılma yeri içeren bir bağlayıcı ile MBP-füzyon Mgm101 oluşturur. Plazmid ilk olarak E. seçerek inşa IPTG ve Xgal beyaz / mavi seçim olmadan coli transformantlar. Elde edilen plazmid üretilmesinde ise pMAL-C2E-MGM101 sonra E. sokulur coli ampisilin ve kloramfenikol dirençli koloniler seçerek BL21-CodonPlus (DE3)-RIL süzün. 1. İfade, İndüksiyon, Hücre Lizis ve DNaz I Tedavi <ol><li> Inocglikoz (% 0.2), ampisilin (100 ug / ml) ve kloramfenikol (50 ug / ml) ile desteklenmiş LB vasatı içinde 10 ml (% 1 Bacto Tripton,% 0.5 maya ekstresi,% 1 NaCl) taze transformantlar ulate. 200 rpm&#39;de çalkalanarak 37 ° CO / K &#39;de inkübe edilir. </li><li> Yukarıdaki gibi desteklenmiş LB vasatı içinde 2 litre içine 10 ml ön-kültür inoküle. OD 600 0.5 ulaşıncaya kadar sallayarak ile 37 ° C hücreleri büyütün. </li><li> 0.3 mM&#39;lik bir son konsantrasyonda izopropil β-D-1-tiogalaktopiranosid (IPTG) eklenerek MBP-Mgm101 füzyon proteininin ekspresyonunu. 5 saat 30 ° C&#39;de sallayarak hücreleri büyütün. </li><li> Bir Beckman JA-10 rotoru (5500 x g, 4 ° C, 10 dakika) kullanılarak santrifüj hücreleri toplamak. Atıldıktan sonra, süpernatan, proteaz inhibitörleri (25 uM löpeptin, 1 uM pepstatin A ve 1 mM PMSF) ihtiva eden liziz tamponu, 30 ml (20 mM Tris-HCI, pH 7.4 ve 1 mM EDTA, pH 7.4) içinde hücre pelletini. </li><li> 20 boyunca buz üzerinde hücre süspansiyonu sonikasyonsn ultrasonik işlemci (Isı Sistemleri; Model W-385) kullanarak 50% görev döngüsü, 30 saniye boyunca buz üzerinde serin ve 2x tekrar sağlar. </li><li> 2 mg / ml &#39;de 1 DNAz stoklar 1 ml ilave edilir. 2 saat boyunca 4 ° C &#39;de hücre lizatı sallayın. </li><li> 500 mM&#39;lik bir son konsantrasyona NaCl ayarlayın. </li><li> 30 dakika boyunca 4 ° C&#39;de 10,000 x g&#39;de santrifüj ile hücre artıkları çıkarın. </li></ol> 2. Amiloz Affinity Kromatografi ile Arıtma <ol><li> Lizis tamponu içinde amiloz reçinesi (% 50 çamurlu) 1.5 ml dengelenmesi. Hücre lizatı ile dengelenmiş amiloz reçine ekleyin. 4 ° CO / N. de hafifçe sallayın </li><li> Soğuk bir odaya monte bir Econo-Kolon kromatografisi kolonuna lizat-reçine karışımı yükleyin. Ilişkisiz proteinler yerçekimi ile sütun geçmesine izin. </li><li> Yıkama tamponu I (, 400 mM NaCI, 1 mM EDTA, pH 7.4, ve 0.2 mM PMSF, 20 mM Tris-HCI, pH 7.4) 300 mL &#39;si ile yıkayınız amiloz reçine. </li><li> II yıkama tamponu (20 mM T 150 mL &#39;si ile yıkama tekrarlayınRIS-HCI, pH 7.4, 200 mM NaCI, 1 mM EDTA, pH 7.4, ve 0.2 mM PMSF). </li><li> Sütun, 4 &#39;de inkübe edilir 10 dakika boyunca ° C toplamak elüsyon tamponu, 5 ml (, 200 mM NaCI;, 1 mM EDTA, pH 7.4 ve 0.2 mM PMSF, 10 mM Maltoz, 20 mM Tris-HCl, pH 7.4) ile ekleme daha fazla kez eluat ve tekrar. </li><li> Eluatlar birleştirin, Coomassie boyama (Şekil 4) tarafından izlenen bir SDS-PAGE jeli üzerinde eluatın bir kısım yükleyerek MBP-Mgm101 verimini ve saflığını belirlemek. </li></ol> 3. PreScission proteaz bölünme ve Katyon Değişim Kromatografisi <ol><li> MBP-Mgm101 elüatına PreScission proteaz 50 adet ekleyin. 4 de bölünme ° CO / N yapın ve (20 mM Tris-HCI, pH 7.4, 100 mM NaCI, 2 mM DTT, 1 mM EDTA, pH 7.4, ve 0.2 mM PMSF) bu diyaliz tampon maddesine karşı diyaliz süresince devam etmesine izin </li><li> Bir SDS-PAGE jel (Şekil 5A) üzerinde bölünme verimini kontrol edin. </li><li> Birden enjekte tarafından bölünmüş MBP-Mgm101 YükBio-Ölçek Mini Makro-Hazırlık Yüksek S kartuşu iyonları bir Bio-Rad Biyolojik Çift Geçişli FPLC sistemine bağlı. </li><li> Bir adım tuzu 5 mM gradyan, 300 mM, 500 mM, 750 mM ve karıştırma tampon A (5 mM NaCI ile oluşturulur NaCl 1.000 mm uygulayarak, katyon değişim kromatografisi başlangıç;, 10 mM Na-fosfat, pH 7.2, 1 mM PMSF) ve Tampon B (1 M NaCI, 10 mM Na-fosfat, pH 7.2, 1 mM PMSF). 0.5 ml / dak akış hızı. Mgm101 fraksiyonu toplamak ve bir SDS-PAGE jel (Şekil 5B), proteinin saflığı gösterir. </li></ol> 4. Boyut Dışlama Kromatografisi <ol><li> Katyon değişim kromatografisinden protein fraksiyonları bir araya getirin. (150 mM NaCI, 1 mM EDTA, pH 7.4, 5 mM 2-merkaptoetanol, 0.2 mM PMSF, 20 mM MOPS, pH 7.0) GF dengeleme tamponu içinde protein Dialyze. </li><li> 4 ° C&#39;de 3000 xg&#39;de iplik ~ 1 ml hacmini azaltmak için Vivaspin 15R Ultrafiltrasyon spin kolon ile protein konsantre </li><li> Mgm101 o Yükna kromatografi tamponu (150 mM NaCI, 5 mM β-merkaptoetanol, 1 mM EDTA, pH 7.4, 0.2 mM PMSF, 20 mM MOPS, pH 7.0) ile dengelenmiş bir Superpose 6 prep kolon dereceli olarak kalibre edilmiştir. </li><li> 0.5 ml / dak &#39;lık bir akış hızında çalışırlar kromatografi tamponu ile boyut dışlama başlatın. </li><li> Saflaştırılmış Mgm101 tepe fraksiyonlar toplayın. Protein nihai kalitesini kontrol etmek için, bir% 12 SDS-PAGE üzerinde fraksiyonların alikotları yerleştirin. </li><li> Vivaspin 6 ile protein konsantre, sonra hızlı bir şekilde -80 sıvı N2 ve mağaza örnekleri dondurmak ° C </li><li> SsDNA bağlayıcı analizi (Şekil 8) ve transmisyon elektron mikroskobu (Şekil 9) ile yapısal görselleştirme için 6-12 ay içinde Mgm101 örnekleri kullanın. </li></ol>

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K., Park, D., Xu, L., Kleckner, N. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=DMC1:+a+meiosis-specific+yeast+homolog+of+E.+coli+recA+required+for+recombination,+synaptonemal+complex+formation,+and+cell+cycle+progression.">DMC1: a meiosis-specific yeast homolog of E. coli recA required for recombination, synaptonemal complex formation, and cell cycle progression.</a> Cell. 69, 439-456 (1992).</li><li>Shinohara, A., Ogawa, H., Ogawa, T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Rad51+protein+involved+in+repair+and+recombination+in+S.+cerevisiae+is+a+RecA-like+protein.">Rad51 protein involved in repair and recombination in S. cerevisiae is a RecA-like protein.</a> Cell. 69, 457-470 (1992).</li><li>Passy, S. I., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Human+Dmc1+protein+binds+DNA+as+an+octameric+ring.">Human Dmc1 protein binds DNA as an octameric ring.</a> Proc. Natl. Acad. Sci. U.S.A. 96, 10684-10688 (1999).</li><li>Story, R. M., Weber, I. T., Steitz, T. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+structure+of+the+E.+coli+recA+protein+monomer+and+polymer.">The structure of the E. coli recA protein monomer and polymer.</a> Nature. 355, 318-325 (1992).</li><li>Yu, X., Jacobs, S. A., West, S. C., Ogawa, T., Egelman, E. 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Yazarlar hiçbir rakip mali çıkarlarının olmadığını beyan ederim.

E. bir istikrarlı, yerli rekombinant Mgm101 proteini üretmek için bir meydan okuma olmuştur bakteri hücrelerinin kendi çözünürlükten muhtemelen nedeniyle coli. Bu raporda, MBP-füzyon stratejisi protein oldukça yüksek bir seviyede ifade edilmesini sağlar olduğunu göstermektedir. Negatif boyama transmisyon elektron mikroskopisi ve boyut dışlama kromatografisi kullanılarak, daha önce MBP-füzyon proteininin in vitro 18 üniform oligomerleri oluşturur göst...

Homolog rekombinasyon çift iplikli sonları tamiri (DSBs) ve zincirler arası çapraz bağlar, ve çökmüş çoğaltma çatal 1 DNA replikasyon reinitiation için önemlidir. Geleneksel homolog rekombinasyon, merkez reaksiyon Prokaryotlarda RecA ve RAD51 ve 1-3 ökaryotlarda Dmc1 da dahil olmak üzere, ATP-bağımlı rekombinaz tarafından katalize edilir. Bu rekombinaz dubleks DNA şablonları (Şekil 1, sol panel) 4-7 içinde homoloji arama ve iplikçik işgali başlatmak için gerekli olan ssDNA, üzerinde nükleoprotein filamentler oluştururlar. Geleneksel programına ilave olarak, aynı zamanda, bir homolog rekombinasyon RecA/Rad51-independent şekilde (Şekil 1, sağ panel) içerisinde yer alabilir. Örneğin, maya Rad52 ve Rad59 proteinler doğrudan dsDNA tatili geriden kestirmeye tarafından sunulan tamamlayıcı ssDNA ipliklerini tavlama katalize edebilir. Şarkı olarak bilinen bu rekombinasyon işlemi,le iplikçik tavlama, genellikle homolog dsDNA şablonları ile eşleştirme anlamına gelmez. Tavlama işleminden sonra, heterolog kuyrukları exonucleases ile çıkarılır ve çentikler genom süreklilik 8-10 geri ligate edilir. Tek tel çekme mekanizması ile tamir genellikle doğrudan tekrar bölgeleri arasında genom dizilerinin silinmesi eşlik eder. Rad52 bakteriyofajlar 11 arasında yaygın olan rekombinasyon proteinlerin çeşitli bir grup aittir. Bu proteinler aynı zamanda, homolog tek sarmallı DNA moleküllerinin tavlama teşvik etmedeki aktiviteleri göre, tek tel çekme Proteinleri (SSAPs) olarak bilinir. En iyi karakterize bakteriyofaj SSAPs Redβ ve laktokokkal faj ul36 gelen profajının rac ve Sak protein bakteriyofajlar λ ve P22, rect gelen Erf vardır. Benzerlik neredeyse undetect rağmen SSAPs yapısal olarak, tipik bir β-β-β-α kat ile karakterize edilirbirincil dizileri mümkün. 10 Onlar tüm form büyük homo-oligomerik halkaları - in vitro 12-14 14 kat simetri. Bu özelliği yüksek mertebeden yapısal organizasyonun fonksiyonel etkileri iyi anlaşılmış değildir. Biz mitokondriyal genom homolog rekombinasyon mekanizması anlamada ilgilendi. Daha önce, Saccharomyces cerevisiae 15 mtDNA bakımı için gerekli olan MGM101 gen tanımlanmıştır. MGM101 sonradan mitokondriyal nukleoidler ile ilişkili olduğu bulunmuştur ve DNA&#39;ya zarar veren ajanlara mtDNA tolerans 16 için gereklidir. Ancak, Mgm101 çalışma rekombinant Mgm101 üretmek için zorluk tarafından son on yılda geri gerçekleştirildi. Biz son zamanlarda E. büyük miktarlarda çözünür Mgm101 üretiminde başardı MBP-füzyon strateji kullanarak coli. Bu bize Mgm101 hisse göstermek sağladıprotein 17,18 en Rad52 aile ile biyokimyasal ve yapısal benzerlikler. Bu raporda, üç aşamalı bir saflaştırma prosedürü homojen Mgm101for biyokimyasal ve yapısal analizleri (Şekil 2) üretir, tarif edilmektedir.

<table border="1" fo:keep-together.within-page="always">
	<tbody>
		<tr>
			<td>Name of Reagent/Material</td>
			<td>Company</td>
			<td>Catalog Number</td>
			<td>Comments</td>
		</tr>
		<tr>
			<td>Expression vector pMAL-c2E</td>
			<td>New England Biolabs</td>
			<td>#N8066S</td>
			<td>&nbsp;</td>
		</tr>
		<tr>
			<td>PreScission Protease</td>
			<td>GE Healthcare Life Sciences</td>
			<td>#27-0843-01</td>
			<td>&nbsp;</td>
		</tr>
		<tr>
			<td>BL21-CodonPlus(DE3)-RIL cells</td>
			<td>Strategene</td>
			<td>#230245</td>
			<td>&nbsp;</td>
		</tr>
		<tr>
			<td>Leupeptin</td>
			<td>Roche Applied Science</td>
			<td>#11034626001</td>
			<td>&nbsp;</td>
		</tr>
		<tr>
			<td>Pepstatin</td>
			<td>Roche Applied Science</td>
			<td>#11359053001</td>
			<td>&nbsp;</td>
		</tr>
		<tr>
			<td>Phenylmethylsulfonyl fluoride (PMSF)</td>
			<td>Roche Applied Science</td>
			<td>#10837091001</td>
			<td>&nbsp;</td>
		</tr>
		<tr>
			<td>DNAse I</td>
			<td>Sigma</td>
			<td>#DN25-1G</td>
			<td>&nbsp;</td>
		</tr>
		<tr>
			<td>Isopropyl &beta;-D-1-thiogalactopyranoside (IPTG)</td>
			<td>Roche Applied Science</td>
			<td>#11411446001</td>
			<td>&nbsp;</td>
		</tr>
		<tr>
			<td>Amylose resin</td>
			<td>New England Biolabs</td>
			<td>#E8021L</td>
			<td>&nbsp;</td>
		</tr>
		<tr>
			<td>Econo-Column chromatography column</td>
			<td>BIO-RAD</td>
			<td>#7372512</td>
			<td>&nbsp;</td>
		</tr>
		<tr>
			<td>Bio-Scale Mini Macro-Prep High S cartridge (1 ml)</td>
			<td>BIO-RAD</td>
			<td>#732-4130</td>
			<td>&nbsp;</td>
		</tr>
		<tr>
			<td>VIVASPIN 15R Ultrafiltration spin column (10,000 MWCO)</td>
			<td>Sartorius Stedium</td>
			<td>#VS15RH02</td>
			<td>&nbsp;</td>
		</tr>
		<tr>
			<td>Superose 6 prep grade column</td>
			<td>Amersham Bioscirnces</td>
			<td>#17-0489-01</td>
			<td>&nbsp;</td>
		</tr>
		<tr>
			<td>VIVASPIN 6 Ultrafiltration spin column (5,000 MWCO)</td>
			<td>Sartorius Stedium</td>
			<td>#VS0611</td>
			<td>&nbsp;</td>
		</tr>
	</tbody>
</table>

preparation of the mgm101 recombination protein by mbp-based tagging strategy

MGM101 gen mitokondriyal DNA bakım rolü için 20 yıl önce tespit edilmiştir. Çeşitli gruplardan çalışmalar Mgm101 protein mitokondriyal DNA recombinational onarım dahil olduğunu ileri sürmüşlerdir. Son araştırmalar Mgm101 Rad52 tipi rekombinasyon protein aile ile ilgili olduğunu göstermiştir. Bu proteinler, büyük oligomerik halkaları oluşturmak ve homolog tek sarmallı DNA moleküllerinin tavlama teşvik eder. Bununla birlikte, Mgm101 karakterizasyonu, rekombinant proteinin üretiminde sekteye edilmiştir. Burada, rekombinant Mgm101 hazırlanması için bir güvenilir bir yöntem tarif edilmektedir. Maltoz bağlanma proteini (MBP)-etiketli Mgm101 olanlar, Escherichia coli içinde ifade edilir. Füzyon proteini, başlangıçta amiloz afinite kromatografisi ile saflaştırılır. Proteolitik bölünme ile serbest bırakıldıktan sonra, Mgm101 katyon değişim kromatografisi ile MBP ayrılır. Monodispers Mgm101 daha sonra elde edilirboyut dışlama kromatografisi ile. Bakteri kültürü litre başına Mgm101 bir ~ 0.87 mg verim rutin elde olabilir. Rekombinant DNA Mgm101 asgari kirlenme vardır. Hazırlanan numunelerin başarıyla Mgm101 biyokimyasal, yapısal ve tek bir parçacık resim analizleri için kullanılır. Bu protokol, aynı zamanda yanlış katlanmış ve bakteri hücreleri için toksik olabilir diğer büyük oligomerik DNA bağlayıcı proteinlerin hazırlanması için kullanılabilir.

Mgm101 mitokondri bir Rad52 ilgili rekombinasyon proteindir. Rad52 yoğun mitokondriyal DNA rekombinasyon (Şekil 1) rolü için incelenmiştir. Rekombinant Mgm101 üç aşamalı bir prosedür (Şekil 2) ile hazırlanabilir. Bu Mgm101 çözünür bir biçimde ifade edilir ve daha sonra (Şekil 3) proteolitik bölünme ile etiketinden açığa çıkmasına izin veren MBP-etiketleme stratejisinin kullanımı ile kolaylaştırılır. Tipik bir ...

Watch this Scientific Journal Video about Preparation of the Mgm101 Recombination Protein by MBP-based Tagging Strategy at JoVE.com

Preparation of the Mgm101 Recombination Protein by MBP-based Tagging Strategy

Maya mitokondriyal nükleoit proteini Mgm101, büyük oligomerik halkalar oluşturan bir Rad52 tipi rekombinasyon proteindir. Bir protokol, maltoz bağlanma proteini (MBP)-etiketleme katyon değişimi ve boyut dışlama kromatografisi ile birlikte stratejisi kullanılarak çözülebilir rekombinant Mgm101 hazırlamak için tarif edilmektedir.

MBP tabanlı Etiketleme Stratejisi Mgm101 Rekombinasyon Protein hazırlanması

The MGM101 gene was identified 20 years ago for its role in the maintenance of mitochondrial DNA. Studies from several groups have suggested that the ...

preparation-mgm101-recombination-protein-mbp-based-tagging

Research

JoVE Journal

Biology

12.0K Görüntüleme.  State University of New York Upstate Medical University. Maya mitokondriyal nükleoit proteini Mgm101, büyük oligomerik halkalar oluşturan bir Rad52 tipi rekombinasyon proteindir. Bir protokol, maltoz bağlanma proteini (MBP)-etiketleme katyon değişimi ve boyut dışlama kromatografisi ile birlikte stratejisi kullanılarak çözülebilir rekombinant Mgm101 hazırlamak için tarif edilmektedir.

Video: Preparation of the Mgm101 Recombination Protein by MBP-based Tagging Strategy

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.

Organik Solvent ve Asetik Asit olmadan Jeller Coomassie G-250 ile Proteinlerin Boyama

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

Biyoloji

Using the GELFREE 8100 Fractionation System for Molecular Weight-Based Fractionation with Liquid Phase Recovery

The GELFREE 8100 Fractionation System is a novel protein fractionation system designed to maximize protein recovery during molecular weight based fractionation. The system is comprised of single-use, 8-sample capacity cartridges and a benchtop GELFREE Fractionation Instrument. During separation, a constant voltage is applied between the anode and cathode reservoirs, and each protein mixture is electrophoretically driven from a loading chamber into a specially designed gel column gel. Proteins are concentrated into a tight band in a stacking gel, and separated based on their respective electrophoretic mobilities in a resolving gel. As proteins elute from the column, they are trapped and concentrated in liquid phase in the collection chamber, free of the gel. The instrument is then paused at specific time intervals, and fractions are collected using a pipette. This process is repeated until all desired fractions have been collected. If fewer than 8 samples are run on a cartridge, any unused chambers can be used in subsequent separations.
This novel technology facilitates the quick and simple separation of up to 8 complex protein mixtures simultaneously, and offers several advantages when compared to previously available fractionation methods. This system is capable of fractionating up to 1mg of total protein per channel, for a total of 8mg per cartridge. Intact proteins over a broad mass range are separated on the basis of molecular weight, retaining important physiochemical properties of the analyte. The liquid phase entrapment provides for high recovery while eliminating the need for band or spot cutting, making the fractionation process highly reproducible1.

The accompanying video describes the use of the GELFREE 8100 Fractionation System, which partitions complex protein samples on the basis of molecular weight and recovers the fractions in liquid phase. The video describes how the technology works, how it is used, and provides resultant data, with polyacrylamide gel electrophoresis analysis of fractionated bovine liver homogenate.

Sıvı Faz Kurtarma Moleküler Ağırlık Tabanlı Fraksiyonu GELFREE 8100 Fraksiyonu Sisteminin Kullanılması

The GELFREE 8100 Fractionation System is a novel protein fractionation system designed to maximize protein recovery during molecular weight based ...

Identifying the Effects of BRCA1 Mutations on Homologous Recombination using Cells that Express Endogenous Wild-type BRCA1

The functional analysis of missense mutations can be complicated by the presence in the cell of the endogenous protein. Structure-function analyses of the BRCA1 have been complicated by the lack of a robust assay for the full length BRCA1 protein and the difficulties inherent in working with cell lines that express hypomorphic BRCA1 protein1,2,3,4,5. We developed a system whereby the endogenous BRCA1 protein in a cell was acutely depleted by RNAi targeting the 3'-UTR of the BRCA1 mRNA and replaced by co-transfecting a plasmid expressing a BRCA1 variant. One advantage of this procedure is that the acute silencing of BRCA1 and simultaneous replacement allow the cells to grow without secondary mutations or adaptations that might arise over time to compensate for the loss of BRCA1 function. This depletion and add-back procedure was done in a HeLa-derived cell line that was readily assayed for homologous recombination activity. The homologous recombination assay is based on a previously published method whereby a recombination substrate is integrated into the genome (Figure 1)6,7,8,9. This recombination substrate has the rare-cutting I-SceI restriction enzyme site inside an inactive GFP allele, and downstream is a second inactive GFP allele. Transfection of the plasmid that expresses I-SceI results in a double-stranded break, which may be repaired by homologous recombination, and if homologous recombination does repair the break it creates an active GFP allele that is readily scored by flow cytometry for GFP protein expression. Depletion of endogenous BRCA1 resulted in an 8-10-fold reduction in homologous recombination activity, and add-back of wild-type plasmid fully restored homologous recombination function. When specific point mutants of full length BRCA1 were expressed from co-transfected plasmids, the effect of the specific missense mutant could be scored. As an example, the expression of the BRCA1(M18T) protein, a variant of unknown clinical significance10, was expressed in these cells, it failed to restore BRCA1-dependent homologous recombination. By contrast, expression of another variant, also of unknown significance, BRCA1(I21V) fully restored BRCA1-dependent homologous recombination function. This strategy of testing the function of BRCA1 missense mutations has been applied to another biological system assaying for centrosome function (Kais et al, unpublished observations). Overall, this approach is suitable for the analysis of missense mutants in any gene that must be analyzed recessively.

We provide a method for testing BRCA1 variants in a tissue culture based assay for homologous recombination repair of DNA damage by depleting endogenous BRCA1 protein from a cell using RNAi and replacing it with a BRCA1 point mutant that contains a coding change.

Endojen Wild-tip BRCA1 Express hücreler kullanarak Homolog Rekombinasyon BRCA1 Mutasyonlar Etkileri belirlenmesi

The functional analysis of missense mutations can be complicated by the presence in the cell of the endogenous protein. Structure-function analyses of the ...

Genetic Modification and Recombination of Salivary Gland Organ Cultures

Branching morphogenesis occurs during the development of many organs, and the embryonic mouse submandibular gland (SMG) is a classical model for the study of branching morphogenesis. In the developing SMG, this process involves iterative steps of epithelial bud and duct formation, to ultimately give rise to a complex branched network of acini and ducts, which serve to produce and modify/transport the saliva, respectively, into the oral cavity1-3. The epithelial-associated basement membrane and aspects of the mesenchymal compartment, including the mesenchyme cells, growth factors and the extracellular matrix, produced by these cells, are critical to the branching mechanism, although how the cellular and molecular events are coordinated remains poorly understood 4. The study of the molecular mechanisms driving epithelial morphogenesis advances our understanding of developmental mechanisms and provides insight into possible regenerative medicine approaches. Such studies have been hampered due to the lack of effective methods for genetic manipulation of the salivary epithelium. Currently, adenoviral transduction represents the most effective method for targeting epithelial cells in adult glands in vivo5. However, in embryonic explants, dense mesenchyme and the basement membrane surrounding the epithelial cells impedes viral access to the epithelial cells. If the mesenchyme is removed, the epithelium can be transfected using adenoviruses, and epithelial rudiments can resume branching morphogenesis in the presence of Matrigel or laminin-1116,7. Mesenchyme-free epithelial rudiment growth also requires additional supplementation with soluble growth factors and does not fully recapitulate branching morphogenesis as it occurs in intact glands8. Here we describe a technique which facilitates adenoviral transduction of epithelial cells and culture of the transfected epithelium with associated mesenchyme. Following microdissection of the embryonic SMGs, removal of the mesenchyme, and viral infection of the epithelium with a GFP-containing adenovirus, we show that the epithelium spontaneously recombines with uninfected mesenchyme, recapitulating intact SMG glandular structure and branching morphogenesis. The genetically modified epithelial cell population can be easily monitored using standard fluorescence microscopy methods, if fluorescently-tagged adenoviral constructs are used. The tissue recombination method described here is currently the most effective and accessible method for transfection of epithelial cells with a wild-type or mutant vector within a complex 3D tissue construct that does not require generation of transgenic animals.

A technique to genetically manipulate epithelial cells within whole ex vivo cultured embryonic mouse submandibular glands (SMGs) using viral gene transfer is described. This method takes advantage of the innate ability of SMG epithelium and mesenchyme to spontaneously recombine after separation and infection of epithelial rudiments with adenoviral vectors.

Tükürük Bezi Organ Kültürleri Genetik Modifikasyon ve Rekombinasyon

Branching  morphogenesis occurs during the development of many organs, and the embryonic  mouse submandibular gland (SMG) is a classical model for the ...

Recombineering Homologous Recombination Constructs in Drosophila

The continued development of techniques for fast, large-scale manipulation of endogenous gene loci will broaden the use of Drosophila melanogaster as a genetic model organism for human-disease related research. Recent years have seen technical advancements like homologous recombination and recombineering. However, generating unequivocal null mutations or tagging endogenous proteins remains a substantial effort for most genes. Here, we describe and demonstrate techniques for using recombineering-based cloning methods to generate vectors that can be used to target and manipulate endogenous loci in vivo. Specifically, we have established a combination of three technologies: (1) BAC transgenesis/recombineering, (2) ends-out homologous recombination and (3) Gateway technology to provide a robust, efficient and flexible method for manipulating endogenous genomic loci. In this protocol, we provide step-by-step details about how to (1) design individual vectors, (2) how to clone large fragments of genomic DNA into the homologous recombination vector using gap repair, and (3) how to replace or tag genes of interest within these vectors using a second round of recombineering. Finally, we will also provide a protocol for how to mobilize these cassettes in vivo to generate a knockout, or a tagged gene via knock-in. These methods can easily be adopted for multiple targets in parallel and provide a means for manipulating the Drosophila genome in a timely and efficient manner.

Recombineering Homologous Recombination Constructs in Drosophila

Homologous recombination techniques greatly advance Drosophila genetics by enabling the creation of molecularly precise mutations. The recent adoption of recombineering allows one to manipulate large pieces of DNA and transform them into Drosophila6. The methods presented here combine these techniques to rapidly generate large homologous recombination vectors.

Homolog rekombinasyon Oluşumlar Recombineering<em&gt; Drosophila</em

The continued development of techniques for fast, large-scale manipulation of endogenous gene loci will broaden the use of Drosophila melanogaster as a ...

Improving the Success Rate of Protein Crystallization by Random Microseed Matrix Screening

Random microseed matrix screening (rMMS) is a protein crystallization technique in which seed crystals are added to random screens. By increasing the likelihood that crystals will grow in the metastable zone of a protein's phase diagram, extra crystallization leads are often obtained, the quality of crystals produced may be increased, and a good supply of crystals for data collection and soaking experiments is provided. Here we describe a general method for rMMS that may be applied to either sitting drop or hanging drop vapor diffusion experiments, established either by hand or using liquid handling robotics, in 96-well or 24-well tray format.

Here we describe a general method for random microseed matrix screening. This technique is shown to significantly increase the success rate of protein crystallization screening experiments, reduce the need for optimization, and provide a reliable supply of crystals for data collection and ligand-soaking experiments.

Rastgele Microseed Matrix ELEME Protein Belirginleşmesine Başarı Oranı artırma

Random microseed matrix screening  (rMMS) is a protein crystallization technique in which seed crystals are added  to random screens. By increasing the ...

Green Fluorescent Protein-based Expression Screening of Membrane Proteins in Escherichia coli

The production of recombinant membrane proteins for structural and functional studies remains technically challenging due to low levels of expression and the inherent instability of many membrane proteins once solubilized in detergents. A protocol is described that combines ligation independent cloning of membrane proteins as GFP fusions with expression in Escherichia coli detected by GFP fluorescence. This enables the construction and expression screening of multiple membrane protein/variants to identify candidates suitable for further investment of time and effort. The GFP reporter is used in a primary screen of expression by visualizing GFP fluorescence following SDS polyacrylamide gel electrophoresis (SDS-PAGE). Membrane proteins that show both a high expression level with minimum degradation as indicated by the absence of free GFP, are selected for a secondary screen. These constructs are scaled and a total membrane fraction prepared and solubilized in four different detergents. Following ultracentrifugation to remove detergent-insoluble material, lysates are analyzed by fluorescence detection size exclusion chromatography (FSEC). Monitoring the size exclusion profile by GFP fluorescence provides information about the mono-dispersity and integrity of the membrane proteins in different detergents. Protein: detergent combinations that elute with a symmetrical peak with little or no free GFP and minimum aggregation are candidates for subsequent purification. Using the above methodology, the heterologous expression in E. coli of SED (shape, elongation, division, and sporulation) proteins from 47 different species of bacteria was analyzed. These proteins typically have ten transmembrane domains and are essential for cell division. The results show that the production of the SEDs orthologues in E. coli was highly variable with respect to the expression levels and integrity of the GFP fusion proteins. The experiment identified a subset for further investigation.

Green Fluorescent Protein-based Expression Screening of Membrane Proteins in Escherichia coli

A streamlined approach to screening for the expression of recombinant membrane proteins in Escherichia coli based on fusion to green fluorescent protein is presented.

Membran proteinlerinin Yeşil floresan proteini temelli Ekspresyon elemesinde<em&gt; Escherichia coli</em

The production of recombinant membrane proteins for structural and functional studies remains technically challenging due to low levels of expression and ...

Detecting Protein Subcellular Localization by Green Fluorescence Protein Tagging and 4',6-Diamidino-2-phenylindole Staining in Caenorhabditis elegans

In this protocol, a green fluorescence protein (GFP) fusion protein and 4',6-diamidino-2-phenylindole (DAPI) staining are used to track protein subcellular localization changes; in particular, a nuclear translocation under a heat stress condition. Proteins react correspondingly to external and internal signals. A common mechanism is to change its subcellular localization. This article describes a protocol to track protein localization that does not require an antibody, radioactive labeling, or a confocal microscope. In this article, GFP is used to tag the target protein EXL-1 in C. elegans, a member of the chloride intracellular channel proteins (CLICs) family, including mammalian CLIC4. An integrated translational exl-1::gfp transgenic line (with a promoter and a full gene sequence) was created by transformation and &#947;-radiation, and stably expresses the gene and gfp. Recent research showed that upon heat stress, not oxidative stress, EXL-1::GFP accumulates in the nucleus. Overlapping the GFP signal with both the nuclei structure and the DAPI signals confirms the EXL-1 subcellular localization changes under stress. This protocol presents two different fixation methods for DAPI staining: ethanol fixation and acetone fixation. The DAPI staining protocol presented in this article is fast and efficient and preserves both the GFP signal and the protein subcellular localization changes. This method only requires a fluorescence microscope with Nomarski, a FITC filter, and a DAPI filter. It is suitable for a small laboratory setting, undergraduate student research, high school student research, and biotechnology classrooms.

Detecting Protein Subcellular Localization by Green Fluorescence Protein Tagging and 4&#039;,6-Diamidino-2-phenylindole Staining in Caenorhabditis elegans

This protocol demonstrates how to track a protein nuclear translocation under heat stress by using a green fluorescence protein (GFP) fusion protein as a marker and 4',6-diamidino-2-phenylindole (DAPI) staining. The DAPI staining protocol is fast and preserves the GFP and protein subcellular localization signals.

Protein hücre altı yerelleştirme yeşil floresans Protein etiketleme ve 4', 6-Diamidino-2-phenylindole Caenorhabditis elegans içinde boyama tarafından tespit

In this protocol, a green fluorescence protein (GFP) fusion protein and 4',6-diamidino-2-phenylindole (DAPI) staining are used to track protein ...

Detecting and Characterizing Protein Self-Assembly In Vivo by Flow Cytometry

Protein self-assembly governs protein function and compartmentalizes cellular processes in space and time. Current methods to study it suffer from low-sensitivity, indirect read-outs, limited throughput, and/or population-level rather than single-cell resolution. We designed a flow cytometry-based single methodology that addresses all of these limitations: Distributed Amphifluoric FRET or DAmFRET. DAmFRET detects and quantifies protein self-assemblies by sensitized emission FRET in vivo, enables deployment across model systems-from yeast to human cells-and achieves sensitive, single-cell, high-throughput read-outs irrespective of protein localization or solubility.

This article describes a FRET-based flow cytometry protocol to quantify protein self-assembly in both S. cerevisiae and HEK293T cells.

Algılama ve ölçme protein Self-montaj In vivo tarafından akış sitometri

Protein self-assembly governs protein function and compartmentalizes cellular processes in space and time. Current methods to study it suffer from ...

An Improved Chemotaxis Assay for the Rapid Identification of Rhizobacterial Chemoattractants in Root Exudates

Chemotaxis identification is very important for the research and application of rhizosphere growth-promoting bacteria. We established a straightforward method to quickly identify the chemoattractants that could induce the chemotactic movement of rhizosphere growth-promoting bacteria on sterile glass slides via simple steps. Bacteria solution (OD600 = 0.5) and sterile chemoattractant aqueous solution were added dropwise on the glass slide at an interval of 1 cm. An inoculating loop was used to connect the chemoattractant aqueous solution to the bacterial solution. The slide was kept at room temperature for 20 min on the clean bench. Finally, the chemoattractant aqueous solution was collected for bacterial counting and microscopic observation. In this study, through multiple comparisons of experimental results, the method overcame multiple shortcomings of traditional bacterial chemotaxis methods. The method reduced the error of plate counting and shortened the experimental cycle. For the identification of chemoattractant substances, this new method can save 2-3 days compared to the traditional method. Additionally, this method allows any researcher to systematically complete a bacterial chemotaxis experiment within 1-2 days. The protocol can be considered a valuable resource for understanding plant-microbe interactions.

Here, we present an improved chemotaxis assay protocol. The goal of this protocol is to reduce the steps and costs of traditional bacterial chemotaxis methods and to serve as a valuable resource for understanding plant-microbe interactions.

Kök Eksüdalarında Rhizobacterial Kemoattractants'ın Hızlı Tanımlanması için Geliştirilmiş Bir Kemotaksi Tahlili

Chemotaxis identification is very important for the research and application of rhizosphere growth-promoting bacteria. We established a straightforward ...