我们感谢斯蒂芬·威尔肯斯在透射电子显微镜的帮助。这项工作是支持由国家机构卫生部授予R01AG023731的。

以前的研究已经表明，第一个氨基末端的22个氨基酸残基的Mgm101裂解后，导入到线粒体19。对于在大肠杆菌中的表达，通过PCR扩增MGM101缺乏的前22个密码子的开放读码框放在男性的编码序列的表达载体pMAL-C2E的修改版本，麦芽糖结合蛋白（MBP）的下游。这会产生的MBP-Mgm101的的断前蛋白酶（ 图3）与一个连接器包含一个切割位点的融合。首次构建质粒选择E。大肠杆菌转化，而 ​​不IPTG和的Xgal蓝色/白选择。将得到的质粒pMAL-C2E MGM101然后导入大肠杆菌大肠杆菌菌株BL21-CodonPlus（DE3）-RIL，选择氨苄青霉素和氯霉素抗性菌落。 1。表达，诱导，细胞裂解和DNase I处理<ol><li>伊诺克ulate新鲜的转化体在10ml补充有葡萄糖（0.2％），氨苄青霉素（100微克/毫升）和氯霉素（50微克/毫升）的LB培养基（1％蛋白胨，0.5％酵母提取物，1％氯化钠）。在200转摇孵育在37°CO / N。 </li><li>为2升与上述补充的LB培养基中，接种10毫升的预培养物。成长的细胞在37℃振荡，直到OD 600达到0.5。 </li><li>通过加入异丙基β-D-1-硫代吡喃半乳糖苷（IPTG），使最终浓度为0.3 mM，的MBP-Mgm101的融合蛋白的诱导表达。 5小时，在30℃振荡，细胞生长。 </li><li>收集细胞，通过离心分离，用Beckman JA-10转子（5500×g离心，4℃下，10分钟）。后弃去上清，重悬细胞沉淀在30ml含有蛋白酶抑制剂亮抑蛋白酶肽（25μM，1μM的胃酶抑素A和1mM的PMSF）的裂解缓冲液（的的20mM Tris-HCl，pH值7.4和1mM EDTA，pH值7.4）。 </li><li>超声细胞悬浮液，冰浴20秒使用超声波处理器（热系统，型号W-385），在占空比为50％时，允许在冰上冷却30秒，然后重复2倍。 </li><li>添加1毫升DNA酶1股票在2毫克/毫升。细胞裂解液在4℃下摇动2小时。 </li><li>调整的NaCl至终浓度为500 mM。 </li><li>中取出的细胞碎片。在4℃下以10,000 xg离心30分钟。 </li></ol> 2。与直链淀粉亲和层析纯化<ol><li>平衡1.5毫升的裂解缓冲液中的直链淀粉树脂（50％浆液）。平衡直链淀粉树脂加入细胞裂解物。轻轻摇动4°CO / N </li><li>加载到Econo柱层析柱安装在冷室中的溶胞产物 - 树脂混合物。允许未结合的蛋白质，通过重力柱。 </li><li>洗净，用300毫升的洗涤缓冲液I（的20mM Tris-盐酸，pH值7.4，400 mM氯化钠，1mM EDTA的溶液，pH值7.4和0.2mM的PMSF）的直链淀粉树脂。 </li><li>重复洗涤用150ml洗涤缓冲液II（20 mm T型的上升HCl，pH值7.4，200 mM氯化钠，1mM的EDTA，pH为7.4，为0.2mM PMSF）。 </li><li>加入5毫升的洗脱缓冲液（的20mM的Tris-HCl，pH值7.4，200 mM氯化钠，1mM EDTA的溶液，pH值7.4和0.2mM的PMSF，10mM的麦芽糖）柱中，温育在4℃下进行10分钟，收集洗脱液重复多次。 </li><li>合并洗脱液，确定通过加载后，以考马斯亮蓝染色（ 图4）上的SDS-PAGE凝胶的洗脱液的等分试样MBP-Mgm101的产率和纯度。 </li></ol> 3。断前蛋白酶裂解和阳离子交换层析<ol><li>添加50单位PreScission蛋白酶到的MBP-Mgm101洗脱液。在4℃下进行裂解位的CO / N，并允许它继续透析过程中对透析缓冲液（的的20mM Tris-HCl，pH值7.4，100 mM氯化钠，2mM的DTT，1mM EDTA的溶液，pH值7.4和0.2mM的PMSF） </li><li> SDS-PAGE凝胶上（ 图5A），检查裂解的效率。 </li><li>由多个注入负荷切割MBP Mgm101离子在生物秤迷你宏观准备高S墨盒连接到Bio-Rad公司生物DuoFlow FPLC系统。 </li><li>开始的阳离子交换色谱法，申请的步骤盐梯度为5mM，300mM的，500毫米，750毫米和1,000 mM NaCl的混合缓冲液A（5 mM氯化钠所建立的;​​的10mM磷酸钠，pH为7.2; mM的PMSF）和缓冲液B（1M NaCl的10mM的磷酸钠，pH为7.2，1mM的PMSF）。设置在0.5毫升/分钟的流速。收集Mgm101馏分和检查产品的纯度的蛋白在SDS-PAGE凝胶（ 图5B）。 </li></ol> 4。尺寸排阻色谱法<ol><li>结合从阳离子交换色谱的蛋白质部分。透析GF平衡缓冲液中的蛋白质（的20mM MOPS，pH为7.0，150 mM氯化钠，1mM的EDTA，pH值7.4，5mM的2 - 巯基乙醇，0.2mM的PMSF）。 </li><li> VIVASPIN 15R超滤离心柱浓缩蛋白，以3000×g在4℃下通过纺丝，以减低音量〜1毫升</li><li>装载Mgm101Ø呐校准SUPEROSE 6制备级柱层析缓冲液平衡过的20mM MOPS，pH为7.0，150 mM氯化钠，5mM的β-巯基乙醇，1mM EDTA的溶液，pH值7.4，0.2mM的PMSF。 </li><li>尺寸排阻色谱运行缓冲液，流速为0.5ml /分钟。 </li><li>收集的零碎，纯化Mgm101峰。负载的等分试样的级分在12％的SDS-PAGE检查蛋白质的最终质量。 </li><li>与VIVASPIN 6浓缩蛋白，然后迅速冻结样品在液氮中并储存在-80℃下</li><li>中使用Mgm101样品在6-12个月内单链DNA结合测定（ 图8），并用透射电子显微镜（ 图9）的结构的可视化。 </li></ol>

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作者宣称，他们有没有竞争经济利益。

它一直是一个挑战，产生一个稳定的，原生的重组Mgm101蛋白E.大肠杆菌可能是由于其在细菌细胞中的不溶性。在这份报告中，我们表明，MBP融合战略使蛋白质表示在相当高的水平。通过负染色透射电子显微镜和尺寸排阻色谱法，我们以前曾表明，MBP的融合蛋白在体外 18形成均匀的低聚物。这是可能的折叠和低聚Mgm101的，可能比较慢线粒体基质相比，细菌细胞中。 unoligomerized Mg...

同源重组是非常重要的双链断裂的修复（DNA双链断裂）和链间交联，并从倒塌的复制叉1重新开始DNA复制。在常规的同源重组，中央的反应由ATP-依赖的重组酶RecA蛋白在原核细胞中，在真核生物中1-3的Rad51和Dmc1。这些重组酶形成核蛋白丝的单链DNA，这是必不可少的双链DNA模板（ 图1，左侧面板）4-7内发起同源搜索和钢绞线入侵。除了 ​​常规的计划，同源重组也可以采取地方在RecA/Rad51-independent的方式（ 图1，右图）。例如，酵母的保守和Rad59蛋白质可以直接催化切除双链DNA断裂露出的互补单链DNA链退火。这个重组过程中，被称为唱乐链退火，一般不涉及同源配对的双链DNA模板。退火后，除去核酸外切酶的异源尾巴刻痕结扎以恢复基因组连续性8-10。常伴有直接重复区域之间的基因组序列缺失修复由单链退火机制。 RAD52属于普遍噬菌体11的重组蛋白质，是一个多元化的群体。这些蛋白质也被称为单链退火蛋白（会计实务准则），根据他们的活动在促进同源的单链DNA分子退火。最好噬菌体会计实务准则Redβ的的ERF从噬菌体λ噬菌体rac和葡激酶蛋白从噬菌体lactococcal UL36和P22，RECT。的会计准则结构其特征在于由一个典型的β-β-β-α倍，虽然相似，几乎检测不到能够在他们的主要序列。他们都形成大的同源寡聚体环10 - 14倍的对称性在体外 12-14。这一特点高阶的组织结构功能的影响还不是很清楚。 我们有兴趣了解线粒体基因组同源重组的机制。我们先前已经确定MGM101是必不可少的维护在酿酒酵母 15线粒体DNA的基因。MGM101后来发现线粒体拟核相关需要的耐受性线粒体DNA损伤剂16。然而，这项研究已Mgm101忍住在过去十年中的难度生产重组Mgm101。最近，我们已经成功地大量生产可溶性Mgm101在从E大肠杆菌使用的MBP融合策略。这使我们能够证明Mgm101股生化和结构的相似性与RAD52家族蛋白17,18。在这份报告中，三个步骤的纯化过程进行了描述，产生均匀Mgm101for的生化和结构分析（ 图2）。

<table><tbody><tr><td>Expression vector pMAL-c2E</td><td>New England Biolabs</td><td>#N8066S</td><td></td></tr><tr><td>PreScission Protease</td><td>GE Healthcare Life Sciences</td><td>#27-0843-01</td><td></td></tr><tr><td>BL21-CodonPlus(DE3)-RIL cells</td><td>Strategene</td><td>#230245</td><td></td></tr><tr><td>Leupeptin</td><td>Roche Applied Science</td><td>#11034626001</td><td></td></tr><tr><td>Pepstatin</td><td>Roche Applied Science</td><td>#11359053001</td><td></td></tr><tr><td>Phenylmethylsulfonyl fluoride (PMSF)</td><td>Roche Applied Science</td><td>#10837091001</td><td></td></tr><tr><td>DNAse I</td><td>Sigma</td><td>#DN25-1G</td><td></td></tr><tr><td>Isopropyl &amp;#946;-D-1-thiogalactopyranoside (IPTG)</td><td>Roche Applied Science</td><td>#11411446001</td><td></td></tr><tr><td>Amylose resin</td><td>New England Biolabs</td><td>#E8021L</td><td></td></tr><tr><td>Econo-Column chromatography column</td><td>BIO-RAD</td><td>#7372512</td><td></td></tr><tr><td>Bio-Scale Mini Macro-Prep High S cartridge (1 ml)</td><td>BIO-RAD</td><td>#732-4130</td><td></td></tr><tr><td>VIVASPIN 15R Ultrafiltration spin column (10,000 MWCO)</td><td>Sartorius Stedium</td><td>#VS15RH02</td><td></td></tr><tr><td>Superose 6 prep grade column</td><td>Amersham Bioscirnces</td><td>#17-0489-01</td><td></td></tr><tr><td>VIVASPIN 6 Ultrafiltration spin column (5,000 MWCO)</td><td>Sartorius Stedium</td><td>#VS0611</td><td></td></tr></tbody></table>

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

20年前被确定MGM101基因维护线粒体DNA中的作用。从几组研究表明，的Mgm101蛋白参与线粒体DNA的重组修复。最近的调查表明，Mgm101 RAD52型重组蛋白家族有关。这些蛋白质形成大的低聚环促进退火同源单链DNA分子。然而，表征阻碍了Mgm101的生产重组蛋白的难度。在这里，用于制备重组Mgm101的一个可靠的程序进行说明。麦芽糖结合蛋白（MBP）标签Mgm101的首先在大肠杆菌中表达。最初是由直链淀粉的亲和层析柱纯化的融合蛋白。在被释放后通过蛋白水解裂解，Mgm101从MBP分离，通过阳离子交换色谱法。然后单分散Mgm101是获得通过尺寸排阻色谱法。可以定期获得的产量为〜0.87毫克每升细菌培养Mgm101。该的重组Mgm101有DNA污染最小。对样品成功地用于生化，结构和单粒子图像分析Mgm101。此步骤也可用于制备其它大的低聚物的DNA结合蛋白，可能会被错误折叠的和细菌细胞毒性的。

Mgm101是一个RAD52在线粒体相关的重组蛋白。 RAD52已被广泛研究，它的作用在线粒体DNA重组（ 图1）。重组Mgm101可以准备通过三个步骤（ 图2）。这是促进所使用的MBP的标记策略，允许以可溶形式表达在Mgm101从标签的蛋白水解裂解，随后被释放（ 图3）。 在一个典型的制备方法中，约2-3毫克，MBP-Mgm101融合可以被回收后，直链淀粉的亲和层析?...

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

酵母线粒体类核蛋白质，Mgm101，是一种重组蛋白RAD52型，形成大低聚环。甲协议的描述以制备可溶性的重组Mgm101使用麦芽糖结合蛋白（MBP）标记加上阳离子交换和尺寸排阻色谱法策略。

MBP基于标记策略的Mgm101重组蛋白的制备

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

Universidad de Cartagena UDEC

Research

JoVE Journal

Biology

12.0K 次观看.  State University of New York Upstate Medical University. 酵母线粒体类核蛋白质，Mgm101，是一种重组蛋白RAD52型，形成大低聚环。甲协议的描述以制备可溶性的重组Mgm101使用麦芽糖结合蛋白（MBP）标记加上阳离子交换和尺寸排阻色谱法策略。

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

Engineering Artificial Factors to Specifically Manipulate Alternative Splicing in Human Cells

The processing of most eukaryotic RNAs is mediated by RNA Binding Proteins (RBPs) with modular configurations, including an RNA recognition module, which specifically binds the pre-mRNA target and an effector domain. Previously, we have taken advantage of the unique RNA binding mode of the PUF domain in human Pumilio 1 to generate a programmable RNA binding scaffold, which was used to engineer various artificial RBPs to manipulate RNA metabolism. Here, a detailed protocol is described to construct Engineered Splicing Factors (ESFs) that are specifically designed to modulate the alternative splicing of target genes. The protocol includes how to design and construct a customized PUF scaffold for a specific RNA target, how to construct an ESF expression plasmid by fusing a designer PUF domain and an effector domain, and how to use ESFs to manipulate the splicing of target genes. In the representative results of this method, we have also described the common assays of ESF activities using splicing reporters, the application of ESF in cultured human cells, and the subsequent effect of splicing changes. By following the detailed protocols in this report, it is possible to design and generate ESFs for the regulation of different types of Alternative Splicing (AS), providing a new strategy to study splicing regulation and the function of different splicing isoforms. Moreover, by fusing different functional domains with a designed PUF domain, researchers can engineer artificial factors that target specific RNAs to manipulate various steps of RNA processing.

This report describes a bioengineering method to design and construct novel Artificial Splicing Factors (ASFs) that specifically modulate the splicing of target genes in mammalian cells. This method can be further expanded to engineer various artificial factors to manipulate other aspects of RNA metabolism.

工程人为因素来特异性地操纵人细胞中的选择性剪接

The processing of most eukaryotic RNAs is mediated by RNA Binding Proteins (RBPs) with modular configurations, including an RNA recognition module, which ...

科研

遗传学

Inducible T7 RNA Polymerase-mediated Multigene Expression System, pMGX

Co-expression of multiple proteins is increasingly essential for synthetic biology, studying protein-protein complexes, and characterizing and harnessing biosynthetic pathways. In this manuscript, the use of a highly effective system for the construction of multigene synthetic operons under the control of an inducible T7 RNA polymerase is described. This system allows many genes to be expressed simultaneously from one plasmid. Here, a set of four related vectors, pMGX-A, pMGX-hisA, pMGX-K, and pMGX-hisK, with either the ampicillin or kanamycin resistance selectable marker (A and K) and either possessing or lacking an N-terminal hexahistidine tag (his) are disclosed. Detailed protocols for the construction of synthetic operons using this vector system are provided along with the corresponding data, showing that a pMGX-based system containing five genes can be readily constructed and used to produce all five encoded proteins in Escherichia coli. This system and protocol enables researchers to routinely express complex multi-component modules and pathways in E. coli.

This study describes methods for the T7-mediated co-expression of multiple genes from a single plasmid in Escherichia coli using the pMGX plasmid system.

可诱导T7 RNA聚合酶介导的多基因表达系统，pMGX

Co-expression of multiple proteins is increasingly essential for synthetic biology, studying protein-protein complexes, and characterizing and harnessing ...

CRISPR/Cas9-mediated Targeted Integration In Vivo Using a Homology-mediated End Joining-based Strategy

As a promising genome editing platform, the CRISPR/Cas9 system has great potential for efficient genetic manipulation, especially for targeted integration of transgenes. However, due to the low efficiency of homologous recombination (HR) and various indel mutations of non-homologous end joining (NHEJ)-based strategies in non-dividing cells, in vivo genome editing remains a great challenge. Here, we describe a homology-mediated end joining (HMEJ)-based CRISPR/Cas9 system for efficient in vivo precise targeted integration. In this system, the targeted genome and the donor vector containing homology arms (~800 bp) flanked by single guide RNA (sgRNA) target sequences are cleaved by CRISPR/Cas9. This HMEJ-based strategy achieves efficient transgene integration in mouse zygotes, as well as in hepatocytes in vivo. Moreover, a HMEJ-based strategy offers an efficient approach for correction of fumarylacetoacetate hydrolase (Fah) mutation in the hepatocytes and rescues Fah-deficiency induced liver failure mice. Taken together, focusing on targeted integration, this HMEJ-based strategy provides a promising tool for a variety of applications, including generation of genetically modified animal models and targeted gene therapies.

CRISPR/Cas9-mediated Targeted Integration In Vivo Using a Homology-mediated End Joining-based Strategy

The clustered regularly interspaced short palindromic repeats/CRISPR associated protein 9 (CRISPR/Cas9) system provides a promising tool for genetic engineering, and opens up the possibility of targeted integration of transgenes. We describe a homology-mediated end joining (HMEJ)-based strategy for efficient DNA targeted integration in vivo and targeted gene therapies using CRISPR/Cas9.

CRISPR/Cas9-mediated 目标集成在体内使用基于同源介导的端接连接策略

As a promising genome editing platform, the CRISPR/Cas9 system has great potential for efficient genetic manipulation, especially for targeted integration ...

Genetic Manipulation in &Delta;ku80 Strains for Functional Genomic Analysis of Toxoplasma gondii

Targeted genetic manipulation using homologous recombination is the method of choice for functional genomic analysis to obtain a detailed view of gene function and phenotype(s). The development of mutant strains with targeted gene deletions, targeted mutations, complemented gene function, and/or tagged genes provides powerful strategies to address gene function, particularly if these genetic manipulations can be efficiently targeted to the gene locus of interest using integration mediated by double cross over homologous recombination.
Due to very high rates of nonhomologous recombination, functional genomic analysis of Toxoplasma gondii has been previously limited by the absence of efficient methods for targeting gene deletions and gene replacements to specific genetic loci. Recently, we abolished the major pathway of nonhomologous recombination in type I and type II strains of T. gondii by deleting the gene encoding the KU80 protein1,2. The &Delta;ku80 strains behave normally during tachyzoite (acute) and bradyzoite (chronic) stages in vitro and in vivo and exhibit essentially a 100% frequency of homologous recombination. The &Delta;ku80 strains make functional genomic studies feasible on the single gene as well as on the genome scale1-4.
Here, we report methods for using type I and type II &Delta;ku80&Delta;hxgprt strains to advance gene targeting approaches in T. gondii. We outline efficient methods for generating gene deletions, gene replacements, and tagged genes by targeted insertion or deletion of the hypoxanthine-xanthine-guanine phosphoribosyltransferase (HXGPRT) selectable marker. The described gene targeting protocol can be used in a variety of ways in &Delta;ku80 strains to advance functional analysis of the parasite genome and to develop single strains that carry multiple targeted genetic manipulations. The application of this genetic method and subsequent phenotypic assays will reveal fundamental and unique aspects of the biology of T. gondii and related significant human pathogens that cause malaria (Plasmodium sp.) and cryptosporidiosis (Cryptosporidium).

Here we report a method for using type I and type II &Delta;ku80 strains of Toxoplasma gondii to efficiently generate targeted gene deletions and gene replacements for functional genomic analysis.

遗传操纵<em&gt;Δku80</em&gt;株功能基因组分析<em&gt;弓形虫</em

Targeted genetic manipulation using homologous recombination is the method of choice for functional genomic analysis to obtain a detailed view of gene ...

免疫与感染

Zebrafish Model of Neuroblastoma Metastasis

Zebrafish has emerged as an important animal model to study human diseases, especially cancer. Along with the robust transgenic and genome editing technologies applied in zebrafish modeling, the ease of maintenance, high-yield productivity, and powerful live imaging altogether make the zebrafish a valuable model system to study metastasis and cellular and molecular bases underlying this process in vivo. The first zebrafish neuroblastoma (NB) model of metastasis was developed by overexpressing two oncogenes, MYCN and LMO1, under control of the dopamine-beta-hydroxylase (d&#946;h) promoter. Co-overexpressed MYCN and LMO1 led to the reduced latency and increased penetrance of neuroblastomagenesis, as well as accelerated distant metastasis of tumor cells. This new model reliably reiterates many key features of human metastatic NB, including involvement of clinically relevant and metastasis-associated genetic alterations; natural and spontaneous development of metastasis in vivo; and conserved sites of metastases. Therefore, the zebrafish model possesses unique advantages to dissect the complex process of tumor metastasis in vivo.

This paper introduces the method of developing, characterizing, and tracking in real-time the tumor metastasis in zebrafish model of neuroblastoma, specifically in the transgenic zebrafish line with overexpression of MYCN and LMO1, which develops metastasis spontaneously.

斑马鱼神经母细胞瘤转移模型

Zebrafish has emerged as an important animal model to study human diseases, especially cancer. Along with the robust transgenic and genome editing ...

癌症研究

Photoactivated Localization Microscopy with Bimolecular Fluorescence Complementation (BiFC-PALM)

Protein-protein interactions (PPIs) are key molecular events to biology. However, it remains a challenge to visualize PPIs with sufficient resolution and sensitivity in cells because the resolution of conventional light microscopy is diffraction-limited to ~250 nm. By combining bimolecular fluorescence complementation (BiFC) with photoactivated localization microscopy (PALM), PPIs can be visualized in cells with single molecule sensitivity and nanometer spatial resolution. BiFC is a commonly used technique for visualizing PPIs with fluorescence contrast, which involves splitting of a fluorescent protein into two non-fluorescent fragments. PALM is a recent superresolution microscopy technique for imaging biological samples at the nanometer and single molecule scales, which uses phototransformable fluorescent probes such as photoactivatable fluorescent proteins (PA-FPs). BiFC-PALM was demonstrated by splitting PAmCherry1, a PA-FP compatible with PALM, for its monomeric nature, good single molecule brightness, high contrast ratio, and utility for stoichiometry measurements. When split between amino acids 159 and 160, PAmCherry1 can be made into a BiFC probe that reconstitutes efficiently at 37 &#176;C with high specificity to PPIs and low non-specific reconstitution. Ras-Raf interaction is used as an example to show how BiFC-PALM helps to probe interactions at the nanometer scale and with single molecule resolution. Their diffusion can also be tracked in live cells using single molecule tracking (smt-) PALM. In this protocol, factors to consider when designing the fusion proteins for BiFC-PALM are discussed, sample preparation, image acquisition, and data analysis steps are explained, and a few exemplary results are showcased. Providing high spatial resolution, specificity, and sensitivity, BiFC-PALM is a useful tool for studying PPIs in intact biological samples.

Photoactivated Localization Microscopy with Bimolecular Fluorescence Complementation BiFC-PALM

Protein-protein interactions are visualized in cells with nanometer spatial resolution by combining bimolecular fluorescence complementation (BiFC) with photoactivated localization microscopy (PALM). Described here is the use of BiFC-PALM for imaging Ras-Raf interactions in U2OS cells for visualizing the nanoscale clustering and diffusion of individual Ras-Raf complexes.

光敏定位显微镜与双分子荧光互补（附设-PALM）

Protein-protein interactions (PPIs) are key molecular events to biology. However, it remains a challenge to visualize PPIs with sufficient resolution and ...

生物工程

Enrichment of Native and Recombinant Extracellular Vesicles of Mycobacteria

Most bacteria, including mycobacteria, generate extracellular vesicles (EVs). Since bacterial EVs (bEVs) contain a subset of cellular components, including metabolites, lipids, proteins, and nucleic acids, several groups have evaluated either the native or recombinant versions of bEVs for their protective potency as subunit vaccine candidates. Unlike native EVs, recombinant EVs are molecularly engineered to contain one or more immunogens of interest. Over the last decade, different groups have explored diverse approaches for generating recombinant bEVs. However, here, we report the design, construction, and enrichment of recombinant mycobacterial EVs (mEVs) in mycobacteria. Towards that, we use Mycobacterium smegmatis (Msm), an avirulent soil mycobacterium as the model system. We first describe the generation and enrichment of native EVs of Msm. Then, we describe the design and construction of recombinant mEVs that contain either mCherry, a red fluorescent reporter protein, or EsxA (Esat-6), a prominent immunogen of Mycobacterium tuberculosis. We achieve this by separately fusing mCherry and EsxA N-termini with the C-terminus of a small Msm protein Cfp-29. Cfp-29 is one of the few abundantly present proteins of MsmEVs. The protocol to generate and enrich recombinant mEVs from Msm remains identical to the generation and enrichment of native EVs of Msm.

This protocol details the enrichment of native mycobacterial extracellular vesicles (mEVs) from axenic cultures of Mycobacterium smegmatis (Msm) and how mCherry (a red fluorescent reporter)-containing recombinant MsmEVs can be designed and enriched. Lastly, it verifies the novel approach with the enrichment of MsmEVs containing the EsxA protein of Mycobacterium tuberculosis.

富集分枝杆菌的天然和重组细胞外囊泡

Most bacteria, including mycobacteria, generate extracellular vesicles (EVs). Since bacterial EVs (bEVs) contain a subset of cellular components, ...

Subcloning Plus Insertion (SPI) - A Novel Recombineering Method for the Rapid Construction of Gene Targeting Vectors

Gene targeting refers to the precise modification of a genetic locus using homologous recombination. The generation of novel cell lines and transgenic mouse models using this method necessitates the construction of a &#8216;targeting&#8217; vector, which contains homologous DNA sequences to the target gene, and has for many years been a limiting step in the process. Vector construction can be performed in vivo in Escherichia coli cells using homologous recombination mediated by phage recombinases using a technique termed recombineering. Recombineering is the preferred technique to subclone the long homology sequences (>4kb) and various targeting elements including selection markers that are required to mediate efficient allelic exchange between a targeting vector and its cognate genomic locus. Typical recombineering protocols follow an iterative scheme of step-wise integration of the targeting elements and require intermediate purification and transformation steps. Here, we present a novel recombineering methodology of vector assembly using a multiplex approach. Plasmid gap repair is performed by the simultaneous capture of genomic sequence from mouse Bacterial Artificial Chromosome libraries and the insertion of dual bacterial and mammalian selection markers. This subcloning plus insertion method is highly efficient and yields a majority of correct recombinants. We present data for the construction of different types of conditional gene knockout, or knock-in, vectors and BAC reporter vectors that have been constructed using this method. SPI vector construction greatly extends the repertoire of the recombineering toolbox and provides a simple, rapid and cost-effective method of constructing these highly complex vectors.

Subcloning Plus Insertion SPI - A Novel Recombineering Method for the Rapid Construction of Gene Targeting Vectors

Gene targeting methodologies can be used to generate transgenic mice with knockout, knock-in and tagged alleles. Here, we describe an improved method of recombineering in E. coli, that we term &#8216;subcloning plus insertion&#8217;, which can be used to generate custom gene targeting vectors rapidly.

亚克隆加插入（SPI） - 一种新型重组工程方法基因打靶载体的快速构建

Gene targeting refers to the precise modification of a genetic locus using homologous recombination. The generation of novel cell lines and transgenic ...

生物学

One-step CRISPR-based Strategy for Endogenous Gene Tagging in Drosophila melanogaster

The study of protein subcellular localization, dynamics, and regulation in live cells has been profoundly transformed by the advent of techniques that allow the tagging of endogenous genes to produce fluorescent fusion proteins. These methods enable researchers to visualize protein behavior in real time, providing valuable insights into their functions and interactions within the cellular environment. Many current gene tagging studies employ a two-step process where visible markers, such as eye color changes, are used to identify genetically modified organisms in the first step, and the visible marker is excised in the second step. Here, we present a one-step protocol to perform precise and rapid endogenous gene tagging in Drosophila melanogaster, which enables screening for engineered lines without the visible eye marker, offering a significant advantage over past methods. To screen for successful gene-tagging events, we employ a PCR-based technique to genotype individual flies by analyzing a small segment from their middle leg. Flies that pass the screening criteria are then used to produce stable stocks. Here, we detail the design and construction of CRISPR editing plasmids and methods for screening and confirmation of engineered lines. Together, this protocol improves the efficiency of endogenous gene tagging in Drosophila significantly and enables studies of cellular processes in vivo.

One-step CRISPR-based Strategy for Endogenous Gene Tagging in Drosophila melanogaster

Here, we present a simplified endogenous gene tagging protocol for Drosophila, which utilizes a PCR-based technique for marker-free identification of successful genetic modifications, facilitating the development of stable knock-in lines.

基于CRISPR的一步法黑腹果蝇内源性基因标记策略

The study of protein subcellular localization, dynamics, and regulation in live cells has been profoundly transformed by the advent of techniques that ...

神经科学

Genetic Modification of Cyanobacteria by Conjugation Using the CyanoGate Modular Cloning Toolkit

Cyanobacteria are a diverse group of prokaryotic photosynthetic organisms that can be genetically modified for the renewable production of useful industrial commodities. Recent advances in synthetic biology have led to development of several cloning toolkits such as CyanoGate, a standardized modular cloning system for building plasmid vectors for subsequent transformation or conjugal transfer into cyanobacteria. Here we outline a detailed method for assembling a self-replicating vector (e.g., carrying a fluorescent marker expression cassette) and conjugal transfer of the vector into the cyanobacterial strains Synechocystis sp. PCC 6803 or Synechococcus elongatus UTEX 2973. In addition, we outline how to characterize the performance of a genetic part (e.g., a promoter) using a plate reader or flow cytometry.

Here, we present a protocol describing how to i) assemble a self-replicating vector using the CyanoGate modular cloning toolkit, ii) introduce the vector into a cyanobacterial host by conjugation, and iii) characterize transgenic cyanobacteria strains using a plate reader or flow cytometry.

MBP基于标记策略的Mgm101重组蛋白的制备

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