Bu araştırma Kanada Doğa Bilimleri ve Mühendislik Konseyi Discovery Grant (NSERC) tarafından desteklenmiştir.

<ol>
	<li>Dobrindt, U., Hochhut, B., Hentschel, U., Hacker, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Genomic+islands+in+pathogenic+and+environmental+microorganisms.">Genomic islands in pathogenic and environmental microorganisms.</a> Nat Rev Microbiol. 2 (5), 414-424 (2004).</li><li>Furuya, E. Y., Lowy, F. 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Yazarlar hiçbir rakip mali çıkarları olduğunu beyan ederim.

Bakteriyel konjugasyon işlemi bakterileri gibi antibiyotik direnç belirteçlerin yayılması gibi zorlu ortamlarda büyümesi için evrimsel bir avantaj sağlayan genleri yayılabilir hangi bir araç sağlar. Konjugatif plazmid çok çok büyük olduğundan, konjugatif plazmid kendisini hedef genlerin mutasyon yoluyla transferi cihazının montajı katılan proteinler üzerinde 12 fonksiyonel çalışmalar hantal vardır. Bu tarifnamede ayrıntılı protokolleri, bir daha kolaylıkla daha küçük, daha ida...

Mikro-organizma düzeyinde genler ve proteinlerin transferi bakteriyel hayatta kalma ve evrim yanı sıra enfeksiyon süreçlerinde önemli bir rol oynar. bakteriler arasında ya da bir bakteri, bir hücre arasındaki DNA değişimi dönüşümü, konjugasyon veya vektör iletimi yoluyla elde edilebilir. 1,2 Konjugasyon Escherichia coli gibi gram negatif bakteriler arasında konjugasyon sırasında dönüşüm ve transdüksiyon kıyasla benzersizdir, DNA transferi kompleks makromoleküler sistemi, verici ve alıcı hücrelerin birbirine bağlayan ve böylece bir verici-kontrollü bir şekilde meydana gelir. Konjugasyon ayrıca bakteri hücrelerinin ana bilgisayar sistemleri için genler, proteinler veya kimyasal enjekte konak hücreleri ile etkileşim içinde en doğrudan yoludur. 3 Oldukça sık, bu tür maddelerin transferi evrimini ve adaptasyon barındırmak için patogenez ve karsinogenez arasında değişen ana bilgisayarda olağanüstü etkileri vardır. O konjugatif recombinatio gösterilmiştirn çevresel stres koşullarında yüksek mutasyon oranları ile bakterilerde adaptasyon 3 kat oranını artırır. 4 Dahası, konjugasyon bakteri türleri antibiyotik direnç genleri yayılır, üzerinden kadar en yaygın yol kullanılarak verilir. 5,6 Mikroorganizmalar hücre zarları arasında makromoleküllerin transferini desteklemek için özel salgı sistemlerinin geliştiğini; tarif edilmiştir de gram negatif bakterilere salgılama sistemleri (TSSler) 9 tip şu anda: T1SS, T2SS, T3SS, T4SS, T5SS, T6SS, T7SS, hem de SEC (sekresyon) ve Tat (iki arginin translokasyon) yollar. Salgı sistemi 7,8 Her tür daha farklı bakteri suşları nedeniyle protein çeşitliliği ve ilgili yolların ayırt edicilik için, farklı alt tipe bir zorunluluk ayrılmıştır. Örneğin, tip IV sekresyon sistemi (T4SS) &#39;de, Ti ve Çağ sistemleri F-plazmid ise efektör taşımacılığının kolaylaştırılması, R27 and pKM101 T4SSs bir konjugatif plazmid transferini kolaylaştırmak. Organizmaların bir alıcı ya da çevresindeki çevre ile hücresel içeriği kendi bileşen proteinlerden kendi salgı sistemlerini monte ve paylaşmak hangi mekanizmaların 7,9,10 ayrıntılı bir anlayış patojen mikroorganizmaları ve süreçlerini mücadele etmek için hedeflenen stratejilerin geliştirilmesinde önemli bir faktördür hücresel enfeksiyon. Lederberg ve Tatum, 11 E. coli içinde, ilk kimlik bakteriyel konjugasyon aşağıdaki mobil ve birleştirici plazmit, çok sayıda belirlenmiş ve karakterize edilmiştir. 12 Bu tür mobil plazmidler ancak tüm mobil plazmidler transferi (oriT) böylece plazmid aktarımını sağlayan kökenini tanıyan bir relaxase içeren, kayda değer aralığı (1 200&#39;den fazla kilobaz (kb) için) boyutu olduğunu gösteriyor. Konjügatif fonksiyonel T4SS montajı için plazmidler daha kodlayan genler aynı zamanda bir türIV birleştirme proteini. 12 Örneğin, E. coli 100 kb F plazmid bir 33.3 kB transferi (tra) bölgedeki tüm konjugatif genleri kodlar. 13 çifti oluşumu (Mpf), DNA transferi ve dışlama fonksiyonlarını çiftleşme pilus oluşumunu kolaylaştırmak tüm proteinler, konjugatif plazmid transferi sırasında F plazmid kodlamak tra bölgesinde genler. 10,14,15 bilginin önemli bir vücut konjugatif T4SSs için kullanılabilir, ancak sadece son zamanlarda kullanılabilir hale gelmektedir konjugatif protein ve komplekslerinin yapısal çalışmalar detaylı. 16-28 konjugatif işlem kapsamlı bir görünümünü monte etmek için, eş transfer proteinlerinin analiz mutasyon için, ayrıntılı yapısal çalışmaların bir bağlantı gereklidir. Bu konjugatif çiftleşme deneyleri ile elde edilebilir. F plazmid için tra bölge içinde kodlanan her protein F aracılı co bir rol oynarnjugation; Bu nedenle, bir transfer geninin nakavt / silme hücre (Şekil 1) konjugatif kapasitesini ortadan kaldıracaktır. küçük mobil plazmidler, F gibi daha büyük konjugatif plasmidler için, standart silme işlemleri için elverişli iken hedef gen, bir farklı antibiyotik dirençli bir gen taşıyıcı ile değiştirilmiş olduğu, bir gen nakavt daha kolay homolog rekombinasyon yoluyla elde edilir. Geçerli protokol, 55 kb F plazmid türevi pOX38-Tc kloramfenikol asetiltransferaz (CAT) ile ilgi bir transfer geni yerine homolog rekombinasyon istihdam; 29,30 Elde edilen nakavt plasmid pOX38-Tc Δgene :: Cm büyüme ortamında kloramfenikol varlığında (cm) karşı direnç kolaylaştırır. pOX38-Tc Δgene :: Cm barındıran donör hücreleri bir çiftleşme testinin kullanımı yoluyla gözlemlenen konjugatif DNA transferi / çiftleşme etkileyecek edemiyoruz; Bir pOX38-Tc Δgene :: Cm donör hücre çiftleşme verimliliği ve normal bir tilki kuyruğusağ- lasa daha sık, kaldırılmasını, azaltmak veya edecektir. pOX38-Tc Δgene :: Cm plazmid konjugatif transferi hedeflenen transferi genini barındıran küçük bir iyileşme plazmid aracılığıyla restore edilebilir. Bu kurtarma plazmid gibi plazmid pK184 (pK184-gen), 31 ya da çok uzun plazmid düzgün hücre (sitoplazma veya periplasmasında) içinde doğru konuma geni hedef olarak uyarılabilir ifade sağlayan biri olarak, kurucu ifade sağlar biri olabilir. Sonuç olarak, bu yeni verici arasındaki birleşme deneylerinde (pOX38-Tc Δgene :: Cm + pK184-geni plazmidler) ve bir alıcı hücre, çiftleşme verimi neredeyse o normal bir alıcı ve verici arasındaki çiftleşme testinin geri yüklemek için bekleniyor. Bu sistem, pK184-gen yapılarına (silme ya da nokta mutasyon) bir dizi nesil boyunca elendikçe genin işlevini prob ve pOX38-Tc Δgene :: Cm barındıran birleşme kapasitesini yeniden kazandırmak için, her yapı yeteneğini test edilmesine imkan verici hücres.

<table><tbody><tr><td>GeneJet Plasmid Mini-Prep Kit</td><td>Fisher Scientific</td><td>K0503</td><td></td></tr><tr><td>GeneJet Gel Extraction Kit</td><td>Fisher Scientific</td><td>K0692</td><td></td></tr><tr><td>GeneJet PCR Purification Kit</td><td>Fisher Scientific</td><td>K0702</td><td></td></tr><tr><td>Q5 Site-Directed Mutagenesis Kit</td><td>New England Biolabs</td><td>E0554S</td><td></td></tr><tr><td>Broad Range DNA Ladder</td><td>New England Biolabs</td><td>N0303A</td><td></td></tr><tr><td>Petri Dishes</td><td>Fisher Scientific</td><td>FB0875713</td><td></td></tr><tr><td>Electroporator</td><td>Eppendorf</td><td>4309000027</td><td></td></tr><tr><td>Electroporation cuvettes</td><td>Fisher Scientific</td><td>FB101</td><td>Cuvettes have a 1 mm gap.</td></tr><tr><td>&lt;strong&gt;Enzymes&lt;/strong&gt;</td><td></td><td></td><td></td></tr><tr><td>AvaI</td><td>New England Biolabs</td><td>R0152S</td><td></td></tr><tr><td>EcoRI</td><td>New England Biolabs</td><td>R0101S</td><td></td></tr><tr><td>HindIII</td><td>New England Biolabs</td><td>R0104L</td><td></td></tr><tr><td>NdeI</td><td>New England Biolabs</td><td>R0111S</td><td></td></tr><tr><td>Phusion DNA Polymerase</td><td>New England Biolabs</td><td>M0530L</td><td></td></tr><tr><td>T4 DNA Ligase</td><td>New England Biolabs</td><td>M0202S</td><td></td></tr><tr><td>DpnI</td><td>New England Biolabs</td><td>R0176S</td><td></td></tr><tr><td>&lt;strong&gt;Antibiotics&lt;/strong&gt;</td><td></td><td></td><td>&lt;strong&gt;Final Concentrations&lt;/strong&gt;</td></tr><tr><td>Chloramphenicol (Cm)</td><td>Fisher Scientific</td><td>BP904-100</td><td>20 &amp;micro;g/mL</td></tr><tr><td>Kanamycin (Km)</td><td>BioBasic Inc.</td><td>DB0286</td><td>50 &amp;micro;g/mL</td></tr><tr><td>Nalidixic acid (Nal)</td><td>Sigma-Aldrich</td><td>N8878-25G</td><td>10 &amp;micro;g/mL</td></tr><tr><td>Rifampicin (Rif)</td><td>Calbiochem</td><td>557303</td><td>20 &amp;micro;g/mL</td></tr><tr><td>Tetracycline (Tc)</td><td>Fisher Scientific</td><td>BP912-100</td><td>10 &amp;micro;g/mL</td></tr><tr><td>Streptomycin (Sm)</td><td>Fisher Scientific</td><td>BP910-50</td><td>50 &amp;micro;g/mL</td></tr></tbody></table>

conjugative mating assays for sequence-specific analysis of transfer proteins involved in bacterial conjugation

The transfer of genetic material by bacterial conjugation is a process that takes place via complexes formed by specific transfer proteins. In Escherichia coli, these transfer proteins make up a DNA transfer machinery known as the mating pair formation, or DNA transfer complex, which facilitates conjugative plasmid transfer. The objective of this paper is to provide a method that can be used to determine the role of a specific transfer protein that is involved in conjugation using a series of deletions and/or point mutations in combination with mating assays. The target gene is knocked out on the conjugative plasmid and is then provided in trans through the use of a small recovery plasmid harboring the target gene. Mutations affecting the target gene on the recovery plasmid can reveal information about functional aspects of the target protein that result in the alteration of mating efficiency of donor cells harboring the mutated gene. Alterations in mating efficiency provide insight into the role and importance of the particular transfer protein, or a region therein, in facilitating conjugative DNA transfer. Coupling this mating assay with detailed three-dimensional structural studies will provide a comprehensive understanding of the function of the conjugative transfer protein as well as provide a means for identifying and characterizing regions of protein-protein interaction.

F plazmid odaklı bakteriyel konjugasyon bir işlem pilus sentezi ve karşılıklı DNA transferi kolaylaştırmak için bir T4SS araya F-plazmidinin tra bölgesi içinde transfer proteinleri içeren koordineli bir süreçtir. Protein TRAF (GenBank erişim # BAA97961, UniProt İD P14497) konjugatif F pilus oluşumu için gereklidir. 10,14,35 - katalitik CXXC motifi olmayan da 37 proteini, bir C-terminali tioredoksin-benzeri domain içerir. Bu N-t...

Watch this Scientific Journal Video about Conjugative Mating Assays for Sequence-specific Analysis of Transfer Proteins Involved in Bacterial Conjugation at JoVE.com

Conjugative Mating Assays for Sequence-specific Analysis of Transfer Proteins Involved in Bacterial Conjugation

Here, we present a protocol to knockout a gene of interest involved in plasmid conjugation and subsequently analyze the impact of its absence using mating assays. The function of the gene is further explored to a specific region of its sequence using deletion or point mutations.

Bakteriyel Konjugasyon ilgilendim Transferi Proteinlerin Dizi özgü Analiz konjugatif Çiftleşme Tahliller

The transfer of genetic material by bacterial conjugation is a process that takes place via complexes formed by specific transfer proteins. In Escherichia ...

conjugative-mating-assays-for-sequence-specific-analysis-transfer

Universidad de Cartagena UDEC

Research

JoVE Journal

Genetics

13.7K Görüntüleme.  York University. Here, we present a protocol to knockout a gene of interest involved in plasmid conjugation and subsequently analyze the impact of its absence using mating assays. The function of the gene is further explored to a specific region of its sequence using deletion or point mutations. 

Video: Conjugative Mating Assays for Sequence-specific Analysis of Transfer Proteins Involved in Bacterial Conjugation

In Vitro Transcription Assays and Their Application in Drug Discovery

In vitro transcription assays have been developed and widely used for many years to study the molecular mechanisms involved in transcription. This process requires multi-subunit DNA-dependent RNA polymerase (RNAP) and a series of transcription factors that act to modulate the activity of RNAP during gene expression. Sequencing gel electrophoresis of radiolabeled transcripts is used to provide detailed mechanistic information on how transcription proceeds and what parameters can affect it. In this paper we describe the protocol to study how the essential elongation factor NusA regulates transcriptional pausing, as well as a method to identify an antibacterial agent targeting transcription initiation through inhibition of RNAP holoenzyme formation. These methods can be used a as platform for the development of additional approaches to explore the mechanism of action of the transcription factors which still remain unclear, as well as new antibacterial agents targeting transcription which is an underutilized drug target in antibiotic research and development.

In Vitro Transcription Assays and Their Application in Drug Discovery

In this manuscript, we describe a protocol to functionally examine transcription and the inhibitory activity of antibacterial agents targeting bacterial transcription.

İn Vitro Transkripsiyon Tahliller ve İlaç Keşfi Onların Uygulama

In vitro transcription assays have been developed and widely used for many years to study the molecular mechanisms involved in transcription. This process ...

Genetik

The Use of Induced Somatic Sector Analysis (ISSA) for Studying Genes and Promoters Involved in Wood Formation and Secondary Stem Development

Secondary stem growth in trees and associated wood formation are significant both from biological and commercial perspectives. However, relatively little is known about the molecular control that governs their development. This is in part due to physical, resource and time limitations often associated with the study of secondary growth processes. A number of in vitro techniques have been used involving either plant part or whole plant system in both woody and non-woody plant species. However, questions about their applicability for the study of secondary stem growth processes, the recalcitrance of certain species and labor intensity are often prohibitive for medium to high throughput applications. Also, when looking at secondary stem development and wood formation the specific traits under investigation might only become measurable late in a tree&#39;s lifecycle after several years of growth. In addressing these challenges alternative in vivo protocols have been developed, named Induced Somatic Sector Analysis, which involve the creation of transgenic somatic tissue sectors directly in the plant&#39;s secondary stem. The aim of this protocol is to provide an efficient, easy and relatively fast means to create transgenic secondary plant tissue for gene and promoter functional characterization that can be utilized in a range of tree species. Results presented here show that transgenic secondary stem sectors can be created in all live tissues and cell types in secondary stems of a variety of tree species and that wood morphological traits as well as promoter expression patterns in secondary stems can be readily assessed facilitating medium to high throughput functional characterization.

The Use of Induced Somatic Sector Analysis ISSA for Studying Genes and Promoters Involved in Wood Formation and Secondary Stem Development

Here we present a protocol that facilitates the medium to high throughput functional characterization of gene and promoter constructs in tree secondary stem tissue within comparatively short time frames. It is efficient, easy to use and widely applicable to a range of tree species.

Ahşap Formasyonu ve İkincil Kök Gelişimi ile ilgilendim Genler ve Promoters incelenmesi için Kaynaklı Somatik Sektör Analizi (ISSA) Kullanımı

Secondary stem growth in trees and associated wood formation are significant both from biological and commercial perspectives. However, relatively little ...

Analysis of Cap-binding Proteins in Human Cells Exposed to Physiological Oxygen Conditions

Translational control is a focal point of gene regulation, especially during periods of cellular stress. Cap-dependent translation via the eIF4F complex is by far the most common pathway to initiate protein synthesis in eukaryotic cells, but stress-specific variations of this complex are now emerging. Purifying cap-binding proteins with an affinity resin composed of Agarose-linked m7GTP (a 5' mRNA cap analog) is a useful tool to identify factors involved in the regulation of translation initiation. Hypoxia (low oxygen) is a cellular stress encountered during fetal development and tumor progression, and is highly dependent on translation regulation. Furthermore, it was recently reported that human adult organs have a lower oxygen content (physioxia 1-9% oxygen) that is closer to hypoxia than the ambient air where cells are routinely cultured. With the ongoing characterization of a hypoxic eIF4F complex (eIF4FH), there is increasing interest in understanding oxygen-dependent translation initiation through the 5' mRNA cap. We have recently developed a human cell culture method to analyze cap-binding proteins that are regulated by oxygen availability. This protocol emphasizes that cell culture and lysis be performed in a hypoxia workstation to eliminate exposure to oxygen. Cells must be incubated for at least 24 hr for the liquid media to equilibrate with the atmosphere within the workstation. To avoid this limitation, pre-conditioned media (de-oxygenated) can be added to cells if shorter time points are required. Certain cap-binding proteins require interactions with a second base or can hydrolyze the m7GTP, therefore some cap interactors may be missed in the purification process. Agarose-linked to enzymatically resistant cap analogs may be substituted in this protocol. This method allows the user to identify novel oxygen-regulated translation factors involved in cap-dependent translation.

Here, we present human cell culture protocols to analyze translation initiation factors that bind the 5' cap of mRNA during physiological oxygen conditions. This method utilizes an Agarose-linked m7GTP cap analog and is suitable to investigate cap-binding factors and their interacting partners.

Fizyolojik Oksijen Koşullarına Maruz İnsan hücrelerinde Cap-bağlayıcı proteinlerin analizi

Translational control is a focal point of gene regulation, especially during periods of cellular stress. Cap-dependent translation via the eIF4F complex ...

High-Resolution Comparison of Bacterial Conjugation Frequencies

Bacterial conjugation is an important step in the horizontal transfer of antibiotic resistance genes via a conjugative DNA element. In-depth comparisons of conjugation frequency under different conditions are required to understand how the conjugative element spreads in nature. However, conventional methods for comparing conjugation frequency are not appropriate for in-depth comparisons because of the high background caused by the occurrence of additional conjugation events on the selective plate. We successfully reduced the background by introducing a most probable number (MPN) method and a higher concentration of antibiotics to prevent further conjugation in selective liquid medium. In addition, we developed a protocol for estimating the probability of how often donor cells initiate conjugation by sorting single donor cells into recipient pools by fluorescence-activated cell sorting (FACS). Using two plasmids, pBP136 and pCAR1, the differences in conjugation frequency in Pseudomonas putida cells could be detected in liquid medium at different stirring rates. The frequencies of conjugation initiation were higher for pBP136 than for pCAR1. Using these results, we can better understand the conjugation features in these two plasmids.

With an aim to understand the behaviors of various bacterial conjugative DNA elements under different conditions, we describe a protocol for detecting differences in conjugation frequency, with high resolution, to estimate how efficiently the donor bacterium initiates conjugation.

Bakteriyel konjugasyon frekans yüksek çözünürlüklü karşılaştırma

Bacterial conjugation is an important step in the horizontal transfer of antibiotic resistance genes via a conjugative DNA element. In-depth comparisons ...

Detection of Horizontal Gene Transfer Mediated by Natural Conjugative Plasmids in E. coli

Conjugation represents one of the main mechanisms facilitating horizontal gene transfer in Gram-negative bacteria. This work describes methods for the study of the mobilization of naturally occurring conjugative plasmids, using two naturally-occurring plasmids as an example. These protocols rely on the differential presence of selectable markers in donor, recipient, and conjugative plasmid. Specifically, the methods described include 1) the identification of natural conjugative plasmids, 2) the quantification of conjugation rates in solid culture, and 3) the diagnostic detection of the antibiotic resistance genes and plasmid replicon types in transconjugant recipients by polymerase chain reaction (PCR). The protocols described here have been developed in the context of studying the evolutionary ecology of horizontal gene transfer, to screen for the presence of conjugative plasmids carrying antibiotic-resistance genes in bacteria found in the environment. The efficient transfer of conjugative plasmids observed in these experiments in culture highlights the biological relevance of conjugation as a mechanism promoting horizontal gene transfer in general and the spread of antibiotic resistance in particular.

Detection of Horizontal Gene Transfer Mediated by Natural Conjugative Plasmids in E. coli

Conjugation mediates horizontal gene transfer by mobilizing plasmid DNA across two different cells, facilitating the spread of beneficial genes. This work describes a widely-used method for the efficient detection of conjugative plasmid transfer, based on the use of differential markers in the conjugative plasmid, donor, and recipient to detect transconjugation.

E. coli'de Doğal Konjugatif Plazmidlerin Aracılık Ettiği Yatay Gen Transferinin Saptanması

Conjugation represents one of the main mechanisms facilitating horizontal gene transfer in Gram-negative bacteria. This work describes methods for the ...

Methodology for the Study of Horizontal Gene Transfer in Staphylococcus aureus

One important feature of the major opportunistic human pathogen Staphylococcus aureus is its extraordinary ability to rapidly acquire resistance to antibiotics. Genomic studies reveal that S. aureus carries many virulence and resistance genes located in mobile genetic elements, suggesting that horizontal gene transfer (HGT) plays a critical role in S. aureus evolution. However, a full and detailed description of the methodology used to study HGT in S. aureus is still lacking, especially regarding natural transformation, which has been recently reported in this bacterium. This work describes three protocols that are useful for the in vitro investigation of HGT in S. aureus: conjugation, phage transduction, and natural transformation. To this aim, the cfr gene (chloramphenicol/florfenicol resistance), which confers the Phenicols, Lincosamides, Oxazolidinones, Pleuromutilins, and Streptogramin A (PhLOPSA)-resistance phenotype, was used. Understanding the mechanisms through which S. aureus transfers genetic materials to other strains is essential to comprehending the rapid acquisition of resistance and helps to clarify the modes of dissemination reported in surveillance programs or to further predict the spreading mode in the future.

Methodology for the Study of Horizontal Gene Transfer in Staphylococcus aureus

We describe here three different protocols for the in vitro investigation of conjugation, transduction, and natural transformation in Staphylococcus aureus.

Yatay Gen Transferi Çalışmasında Metodolojisi<em&gt; Staphylococcus aureus</em

One important feature of the major opportunistic human pathogen Staphylococcus aureus is its extraordinary ability to rapidly acquire resistance to ...

İmmünoloji ve Enfeksiyon

Creation of a Dense Transposon Insertion Library Using Bacterial Conjugation in Enterobacterial Strains Such As Escherichia Coli or Shigella flexneri

Transposon mutagenesis is a method that allows gene disruption via the random genomic insertion of a piece of DNA called a transposon. The protocol below outlines a method for high efficiency transfer between bacterial strains of a plasmid harboring a transposon containing a kanamycin resistance marker. The plasmid-borne transposase is encoded by a variant tnp gene that inserts the transposon into the genome of the recipient strain with very low insertional bias. This method thus allows the creation of large mutant libraries in which transposons have been inserted into unique genomic positions in a recipient strain of either Escherichia coli or Shigella flexneri bacteria. By using bacterial conjugation, as opposed to other methods such as electroporation or chemical transformation, large libraries with hundreds of thousands of unique clones can be created. This yields high-density insertion libraries, with insertions occurring as frequently as every 4-6 base pairs in non-essential genes. This method is superior to other methods as it allows for an inexpensive, easy to use, and high efficiency method for the creation of a dense transposon insertion library. The transposon library can be used in downstream applications such as transposon sequencing (Tn-Seq), to infer genetic interaction networks, or more simply, in mutational (forward genetic) screens.

Creation of a Dense Transposon Insertion Library Using Bacterial Conjugation in Enterobacterial Strains Such As Escherichia Coli or Shigella flexneri

Presented here is a simple method for creating a high-density transposon insertion library in Escherichia coli or Shigella flexneri using bacterial conjugation. This protocol allows the creation of a collection of hundreds of thousands of unique mutants in bacteria by the random genomic insertion of a transposon.

Bir yoğun Transposon ekleme kütüphane kullanarak bakteriyel konjugasyon Escherichia Coli Enterobacterial suşları gibi veya Shigella flexneri oluşturulması

Transposon mutagenesis is a method that allows gene disruption via the random genomic insertion of a piece of DNA called a transposon. The protocol below ...

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.

CyanoGate Modüler Klonlama Araç Kiti Kullanılarak Konjugasyon ile Siyanobakterilerin Genetik Modifikasyonu

Cyanobacteria are a diverse group of prokaryotic photosynthetic organisms that can be genetically modified for the renewable production of useful ...

Biyoloji

Generating Transposon Insertion Libraries in Gram-Negative Bacteria for High-Throughput Sequencing

Transposon sequencing (Tn-seq) is a powerful method that combines transposon mutagenesis and massive parallel sequencing to identify genes and pathways that contribute to bacterial fitness under a wide range of environmental conditions. Tn-seq applications are extensive and have not only enabled examination of genotype-phenotype relationships at an organism level but also at the population, community and systems levels. Gram-negative bacteria are highly associated with antimicrobial resistance phenotypes, which has increased incidents of antibiotic treatment failure. Antimicrobial resistance is defined as bacterial growth in the presence of otherwise lethal antibiotics. The &#8220;last-line&#8221; antimicrobial colistin is used to treat Gram-negative bacterial infections. However, several Gram-negative pathogens, including Acinetobacter baumannii can develop colistin resistance through a range of molecular mechanisms, some of which were characterized using Tn-seq. Furthermore, signal transduction pathways that regulate colistin resistance vary within Gram-negative bacteria. Here we propose an efficient method of transposon mutagenesis in A. baumannii that streamlines generation of a saturating transposon insertion library and amplicon library construction by eliminating the need for restriction enzymes, adapter ligation, and gel purification. The methods described herein will enable in-depth analysis of molecular determinants that contribute to A. baumannii fitness when challenged with colistin. The protocol is also applicable to other Gram-negative ESKAPE pathogens, which are primarily associated with drug resistant hospital-acquired infections.

We describe a method to generate saturating transposon mutant libraries in Gram-negative bacteria and subsequent preparation of DNA amplicon libraries for high-throughput sequencing. As an example, we focus on the ESKAPE pathogen, Acinetobacter baumannii, but this protocol is amenable to a wide range of Gram-negative organisms.

Yüksek İşlem Likör Sıralaması Için Gram-Negatif Bakterilerde Transposon Ekleme Kitaplıkları Oluşturma

Transposon sequencing (Tn-seq) is a powerful method that combines transposon mutagenesis and massive parallel sequencing to identify genes and pathways ...

Conjugation: A Method to Transfer Ampicillin Resistance from Donor to Recipient E. coli

Source: Alexander S. Gold1, Tonya M. Colpitts1 
1 Department of Microbiology, Boston University School of Medicine, National Emerging Infections Diseases Laboratories, Boston, MA
First discovered by Lederberg and Tatum in 1946, conjugation is a form of horizontal gene transfer between bacteria that relies on direct physical contact between two bacterial cells (1). Unlike other forms of gene transfer, such as transformation or transduction, conjugation is a naturally occurring process in which DNA is secreted from a donor cell to a recipient cell in a unidirectional manner. This directionality and the ability for this process to increase the genetic diversity of bacteria has given conjugation the reputation as a form of bacterial &#34;mating,&#34; which is believed to have contributed greatly to the recent rise in antibiotic resistant bacteria (2, 3). By using selective pressures, for example the use of antibiotics, conjugation has been manipulated for use in the laboratory setting, making it a powerful tool for horizontal gene transfer between bacteria, and in some cases from bacteria to yeast, plant, and animal cells (4). Apart from applications in the laboratory, bacterium-eukaryote gene transfer by conjugation is an exciting avenue of DNA transfer with a multitude of possible biotechnical applications and naturally occurring implications (5).
Conjugation is thought to work by a &#34;two-step mechanism&#34; (6). First, before any DNA can be transferred, the donor cell must make direct cell-to-cell contact with the recipient. This process has been characterized best in gram-negative bacteria, the most studied of which is Escherichia coli. Cell-to-cell contact is established by the presence of a complex network of extracellular filaments on the donor known as the sex pilus, a conjugative element encoded for by the transferable gene known as the F (fertility) factor (7, 8). In addition to establishing contact between donor and recipient, several proteins are transported via the sex pilus to the recipient cytoplasm, forming a type IV secretion system (T4SS) conduit between the two cells, a necessary structure for the second step of conjugation, DNA transfer (6). By combining this function of the sex pilus with rolling circle replication of DNA, the donor cell is able to transfer DNA in the form of a transposable element, such as a plasmid or transposon, to the recipient by a &#34;shoot and pump&#34; model (6). In this case, the &#34;shooting&#34; is the transport of the pilot protein, with linked DNA, by the T4SS into the recipient cell, and the &#34;pumping&#34; is the active transport of DNA to the recipient, a process reliant on the T4SS and catalyzed by coupling proteins (6). The machinery used in this this process is composed of an origin of transfer sequence (oriT), which must be provided by the DNA in cis and trans genes, which encode a relaxase, mate pair formation complex, and type IV coupling protein, and can be present in cis or trans (9). This relaxase cleaves the nic site within the oriT sequence and covalently attaches to the 5&#39; end of the transferred strand to produce the relaxosome, a single-stranded DNA-relaxase complex with other auxiliary proteins (9). Once formed, the relaxosome connects to the mating pair formation complex, via the type IV coupling protein, which allows for the transfer of the ssDNA-relaxase complex into recipient cells by the T4SS (10). Once in the cytoplasm of the recipient, the DNA can integrate into the recipient genome or exist separately in the form of a plasmid, either of which allow for the expression of its genes.
In this experiment, the widely used conjugation donor strain E. coli WM3064 was used to transfer the gene encoding for ampicillin resistance to the recipient strain E. coli J53. While both strains of the gram-negative bacteria were resistant to tetracycline, only the donor strain WM3064 had the gene for ampicillin resistance, encoded for in the pWD2-oriT shuttle vector, and was auxotrophic to diaminopimelic acid (DAP) (11-13). This experiment consisted of two main steps, the preparation of donor and recipient strains, followed by the transfer of the ampicillin resistance gene from donor to recipient by conjugation (Figure 1).
<img alt="Figure 1" class="xfigimg" src="/files/ftp_upload/10516/10516fig1.jpg" /> 
Figure 1: Conjugation schematic. This schematic shows the successful transfer of a plasmid, only one example of a transposable DNA element, from a donor cell to a recipient cell using conjugation. Upon contact with the recipient cell by the donor cell via the sex pilus, the plasmid replicates by rolling circle replication, moves through the multiprotein complex joining the two cells, and forms a new full-length plasmid in the recipient cell.
By incubating a mixture of donor and recipient cells, then successively plating these cells in the presence of tetracycline and DAP, this allowed for the successful transfer of the ampicillin resistance gene. Successively plating cells grown from this mixture in the presence of tetracycline and ampicillin, removed all donor cells due to the lack of DAP and any recipient cells that may not have gained the ampicillin resistance gene, yielding strictly recipient J53 strain bacteria that acquired ampicillin resistance (Figure 2). Once carried out, the successful transfer of the ampicillin resistance gene was confirmed by PCR. Since conjugation was successful, the J53 strain of E. coli contained pWD2-oriT and was resistant to ampicillin, and the gene encoding for this resistance is detectable by PCR. However, if unsuccessful there would have been no detection of the ampicillin resistance gene and ampicillin would still function as an effective antibiotic against the J53 strain.
<img alt="Figure 2" class="xfigimg" src="/files/ftp_upload/10516/10516fig2.jpg" /> 
Figure 2: Protocol schematic. This schematic shows an overview of the presented protocol.
<img alt="Figure 3A" class="xfigimg" src="/files/ftp_upload/10516/10516fig3a.jpg" /> 
Figure 3A: The confirmation of successful conjugation by PCR. A) Freezer stocks of the conjugated and negative control samples were streaked out on agar plates and a colony was selected (red) for DNA isolation.

Conjugation: Transferring Ampicillin Resistance in E. coli

Source: Alexander S. Gold1, Tonya M. Colpitts1
1 Department of Microbiology, Boston University School of Medicine, National Emerging Infections Diseases ...