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  1. Article ; Online: Mapping Transposon Insertion Sites by Inverse Polymerase Chain Reaction and Sanger Sequencing.

    Figueroa-Bossi, Nara / Balbontín, Roberto / Bossi, Lionello

    Cold Spring Harbor protocols

    2024  Volume 2024, Issue 5, Page(s) 108197

    Abstract: Inverse polymerase chain reaction (PCR) is a method designed to amplify a segment of DNA for which only a portion of the sequence is known. The method consists of circularizing the DNA fragment by self-ligation and performing PCR with primers annealing ... ...

    Abstract Inverse polymerase chain reaction (PCR) is a method designed to amplify a segment of DNA for which only a portion of the sequence is known. The method consists of circularizing the DNA fragment by self-ligation and performing PCR with primers annealing inside the known sequence but pointing away from each other (hence the technique is also called "inside-out PCR"). Here we describe how inverse PCR can be used to identify the site of transposon insertion in the bacterial chromosome. This protocol, implemented here with a class of transposons generating reporter gene fusions, involves (i) preparing genomic DNA from the strain harboring the unknown insertion, (ii) cleaving the genomic DNA with a restriction enzyme, (iii) performing a ligation reaction under conditions favoring circularization of the DNA fragments, and (iv) performing inverse PCRs with inside-out primers annealing near either or both termini of the transposon. This last step results in the amplification of the chromosomal sequences immediately adjacent to the transposon, which can then be identified by Sanger sequencing. The protocol can be performed in parallel on several strains providing an effective and economic way for rapidly identifying multiple transposon insertion sites.
    MeSH term(s) DNA Transposable Elements/genetics ; Polymerase Chain Reaction/methods ; Sequence Analysis, DNA/methods ; DNA, Bacterial/genetics ; Mutagenesis, Insertional/methods ; DNA Primers/genetics
    Chemical Substances DNA Transposable Elements ; DNA, Bacterial ; DNA Primers
    Language English
    Publishing date 2024-05-02
    Publishing country United States
    Document type Journal Article ; Research Support, Non-U.S. Gov't
    ISSN 1559-6095
    ISSN (online) 1559-6095
    DOI 10.1101/pdb.prot108197
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  2. Article ; Online: Use of Transposable Reporters in the Analysis of Bacterial Regulatory Networks.

    Figueroa-Bossi, Nara / Balbontín, Roberto / Bossi, Lionello

    Cold Spring Harbor protocols

    2024  Volume 2024, Issue 5, Page(s) 108327

    Abstract: Transposable elements are genetic entities that have the capacity to promote their own translocation from one site to another within a genome. Initially discovered ... ...

    Abstract Transposable elements are genetic entities that have the capacity to promote their own translocation from one site to another within a genome. Initially discovered in
    MeSH term(s) DNA Transposable Elements/genetics ; Genes, Reporter/genetics ; Gene Regulatory Networks ; Bacteria/genetics ; Gene Expression Regulation, Bacterial
    Chemical Substances DNA Transposable Elements
    Language English
    Publishing date 2024-05-02
    Publishing country United States
    Document type Journal Article ; Research Support, Non-U.S. Gov't
    ISSN 1559-6095
    ISSN (online) 1559-6095
    DOI 10.1101/pdb.top108327
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  3. Article ; Online: Generating Libraries of Random

    Figueroa-Bossi, Nara / Balbontín, Roberto / Bossi, Lionello

    Cold Spring Harbor protocols

    2024  Volume 2024, Issue 5, Page(s) 108196

    Abstract: Transposable elements engineered to generate random gene fusions in the bacterial chromosome are valuable tools in the study of gene expression. In this protocol, we describe the use of a new series of transposons designed to obtain random fusions to ... ...

    Abstract Transposable elements engineered to generate random gene fusions in the bacterial chromosome are valuable tools in the study of gene expression. In this protocol, we describe the use of a new series of transposons designed to obtain random fusions to either the
    MeSH term(s) Green Fluorescent Proteins/genetics ; Green Fluorescent Proteins/metabolism ; DNA Transposable Elements/genetics ; Chromosomes, Bacterial/genetics ; Gene Fusion ; Plasmids/genetics ; Lac Operon/genetics ; Gene Library ; Transposases/genetics ; Transposases/metabolism
    Chemical Substances Green Fluorescent Proteins (147336-22-9) ; DNA Transposable Elements ; Transposases (EC 2.7.7.-)
    Language English
    Publishing date 2024-05-02
    Publishing country United States
    Document type Journal Article ; Research Support, Non-U.S. Gov't
    ISSN 1559-6095
    ISSN (online) 1559-6095
    DOI 10.1101/pdb.prot108196
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  4. Article ; Online: Scarless DNA Recombineering.

    Figueroa-Bossi, Nara / Balbontín, Roberto / Bossi, Lionello

    Cold Spring Harbor protocols

    2023  Volume 2023, Issue 9, Page(s) 638–650

    Abstract: The method described here allows editing of the bacterial genome without leaving any secondary changes (scars) behind. This method uses a tripartite selectable and counterselectable cassette comprising an antibiotic-resistance gene ( ...

    Abstract The method described here allows editing of the bacterial genome without leaving any secondary changes (scars) behind. This method uses a tripartite selectable and counterselectable cassette comprising an antibiotic-resistance gene (
    MeSH term(s) Plasmids/genetics ; DNA ; Anti-Bacterial Agents ; Promoter Regions, Genetic
    Chemical Substances DNA (9007-49-2) ; Anti-Bacterial Agents
    Language English
    Publishing date 2023-09-01
    Publishing country United States
    Document type Journal Article ; Research Support, Non-U.S. Gov't
    ISSN 1559-6095
    ISSN (online) 1559-6095
    DOI 10.1101/pdb.prot107857
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  5. Article ; Online: Recombineering 101: Making an in-Frame Deletion Mutant.

    Figueroa-Bossi, Nara / Balbontín, Roberto / Bossi, Lionello

    Cold Spring Harbor protocols

    2023  Volume 2023, Issue 9, Page(s) 628–637

    Abstract: DNA recombineering uses phage λ Red recombination functions to promote integration of DNA fragments generated by polymerase chain reaction (PCR) into the bacterial chromosome. The PCR primers are designed to have the last 18-22 nt anneal on either side ... ...

    Abstract DNA recombineering uses phage λ Red recombination functions to promote integration of DNA fragments generated by polymerase chain reaction (PCR) into the bacterial chromosome. The PCR primers are designed to have the last 18-22 nt anneal on either side of the donor DNA and to carry 40- to 50-nt 5' extensions homologous to the sequences flanking the chosen insertion site. The simplest application of the method results in knockout mutants of nonessential genes. Deletions can be constructed by replacing a portion or the entirety of a target gene with an antibiotic-resistance cassette. In some commonly used template plasmids, the antibiotic-resistance gene can be coamplified with a pair of flanking FRT (Flp recombinase recognition target) sites that, following insertion of the fragment into the chromosome, allow excision of the antibiotic-resistance cassette via the activity of the site-specific Flp recombinase. The excision step leaves behind a "scar" sequence comprising an FRT site and flanking primer annealing sequences. Removal of the cassette minimizes undesired perturbations on the expression of neighboring genes. Even so, polarity effects can result from the occurrence of stop codons within, or downstream of, the scar sequence. These problems can be avoided by the appropriate choice of the template and by designing primers so that the reading frame of the target gene is maintained past the deletion end point. This protocol is optimized for use with
    MeSH term(s) Plasmids ; Sequence Deletion ; DNA ; Polymerase Chain Reaction
    Chemical Substances DNA (9007-49-2)
    Language English
    Publishing date 2023-09-01
    Publishing country United States
    Document type Journal Article ; Research Support, Non-U.S. Gov't
    ISSN 1559-6095
    ISSN (online) 1559-6095
    DOI 10.1101/pdb.prot107856
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  6. Article ; Online: DNA Recombineering Applications.

    Figueroa-Bossi, Nara / Balbontín, Roberto / Bossi, Lionello

    Cold Spring Harbor protocols

    2023  Volume 2023, Issue 9, Page(s) 601–606

    Abstract: The ability to manipulate the bacterial genome is an obligatory premise for the study of gene function and regulation in bacterial cells. The λ red recombineering technique allows modification of chromosomal sequences with base-pair precision without the ...

    Abstract The ability to manipulate the bacterial genome is an obligatory premise for the study of gene function and regulation in bacterial cells. The λ red recombineering technique allows modification of chromosomal sequences with base-pair precision without the need of intermediate molecular cloning steps. Initially conceived to construct insertion mutants, the technique lends itself to a wide variety of applications including the creation of point mutants, seamless deletions, reporter, and epitope tag fusions and chromosomal rearrangements. Here, we introduce some of the most common implementations of the method.
    MeSH term(s) Genetic Engineering/methods ; DNA/genetics ; Cloning, Molecular
    Chemical Substances DNA (9007-49-2)
    Language English
    Publishing date 2023-09-01
    Publishing country United States
    Document type Journal Article ; Research Support, Non-U.S. Gov't
    ISSN 1559-6095
    ISSN (online) 1559-6095
    DOI 10.1101/pdb.top107855
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  7. Article ; Online: Construction of Single-Copy Fluorescent Protein Fusions by One-Step Recombineering.

    Balbontín, Roberto / Figueroa-Bossi, Nara / Bossi, Lionello

    Cold Spring Harbor protocols

    2023  Volume 2023, Issue 9, Page(s) 651–662

    Abstract: We describe a simple recombineering-based procedure for generating single-copy gene fusions to superfolder GFP (sfGFP) and monomeric Cherry (mCherry). The open reading frame (orf) for either protein is inserted at the targeted chromosomal location by λ ... ...

    Abstract We describe a simple recombineering-based procedure for generating single-copy gene fusions to superfolder GFP (sfGFP) and monomeric Cherry (mCherry). The open reading frame (orf) for either protein is inserted at the targeted chromosomal location by λ Red recombination using an adjacent drug-resistance cassette (
    MeSH term(s) Green Fluorescent Proteins/genetics ; Gene Fusion
    Chemical Substances Green Fluorescent Proteins (147336-22-9)
    Language English
    Publishing date 2023-09-01
    Publishing country United States
    Document type Journal Article ; Research Support, Non-U.S. Gov't
    ISSN 1559-6095
    ISSN (online) 1559-6095
    DOI 10.1101/pdb.prot107950
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  8. Article ; Online: Corrigendum: Scarless DNA Recombineering.

    Figueroa-Bossi, Nara / Balbontín, Roberto / Bossi, Lionello

    Cold Spring Harbor protocols

    2023  Volume 2023, Issue 9, Page(s) pdb.corr108466

    Language English
    Publishing date 2023-09-01
    Publishing country United States
    Document type Journal Article ; Published Erratum
    ISSN 1559-6095
    ISSN (online) 1559-6095
    DOI 10.1101/pdb.corr108466
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  9. Article ; Online: Converting an FRT-Tagged Gene into a Fluorescent Protein Gene Fusion by Flp-Mediated Site-Specific Recombination.

    Balbontín, Roberto / Ratel, Mathilde / Figueroa-Bossi, Nara / Bossi, Lionello

    Cold Spring Harbor protocols

    2023  Volume 2023, Issue 9, Page(s) 663–670

    Abstract: This protocol uses conditional plasmids carrying the open reading frame (orf) of either superfolder green fluorescent protein (sfGFP) or monomeric Cherry (mCherry) fused to a flippase (Flp) recognition target (FRT) site. In cells expressing the Flp ... ...

    Abstract This protocol uses conditional plasmids carrying the open reading frame (orf) of either superfolder green fluorescent protein (sfGFP) or monomeric Cherry (mCherry) fused to a flippase (Flp) recognition target (FRT) site. In cells expressing the Flp enzyme, site-specific recombination between the plasmid-borne FRT and an FRT "scar" in a target gene in the bacterial chromosome results in chromosomal integration of the plasmid with the concomitant in-frame fusion of the target gene to the fluorescent protein orf. This event can be positively selected using an antibiotic-resistance marker (
    MeSH term(s) Recombination, Genetic ; DNA Nucleotidyltransferases/genetics ; DNA Nucleotidyltransferases/metabolism ; Plasmids/genetics ; Gene Fusion ; Genes, Reporter
    Chemical Substances DNA Nucleotidyltransferases (EC 2.7.7.-)
    Language English
    Publishing date 2023-09-01
    Publishing country United States
    Document type Journal Article ; Research Support, Non-U.S. Gov't
    ISSN 1559-6095
    ISSN (online) 1559-6095
    DOI 10.1101/pdb.prot107951
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  10. Article ; Online: Basic Bacteriological Routines.

    Figueroa-Bossi, Nara / Balbontín, Roberto / Bossi, Lionello

    Cold Spring Harbor protocols

    2022  Volume 2022, Issue 10, Page(s) Pdb.prot107849

    Abstract: In experimental bacteriology, bacteria are generally manipulated, stored, and shipped in the form of cultures. Depending on various factors, including strain genotype, storage and shipping methods, and manipulator skills, the culture may contain genetic ... ...

    Abstract In experimental bacteriology, bacteria are generally manipulated, stored, and shipped in the form of cultures. Depending on various factors, including strain genotype, storage and shipping methods, and manipulator skills, the culture may contain genetic variants or simply contaminants. It is therefore important to begin an experiment by streaking the culture on an agar plate. Streaking, a technique to disperse bacterial cells on the surface of the agar, serves the purpose of isolating individual colonies. A colony originates from a single cell and is a nearly pure culture. On rich LB medium after 24 h of incubation at 37°C, a colony of Salmonella contains ∼5 × 10<sup>8</sup> cells (about 29 generations). Streaking is also required in experiments that themselves generate single colonies as a result of selection (e.g., when constructing strains or introducing plasmids). Except in the few instances in which the selection efficiently kills all counter-selected bacteria, colonies growing on the selective plates are contaminated, sometimes heavily, with cells from the bacterial lawn. "Purifying" the colonies arising in such experiments by streaking on selective plates is therefore a mandatory step. Here, we show how this can be conveniently done using simple toothpicks. We also briefly describe the steps involved in inoculating liquid cultures, spreading plates, and replica plating.
    MeSH term(s) Agar ; Bacteria ; Colony Count, Microbial ; Culture Media
    Chemical Substances Culture Media ; Agar (9002-18-0)
    Language English
    Publishing date 2022-10-03
    Publishing country United States
    Document type Journal Article ; Research Support, Non-U.S. Gov't
    ISSN 1559-6095
    ISSN (online) 1559-6095
    DOI 10.1101/pdb.prot107849
    Database MEDical Literature Analysis and Retrieval System OnLINE

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