I would like to acknowledge Olga de Souza Silva for technical assistance. This work was supported by Swiss National Science Foundation (SNSF) Grant 31003A_127029.

The TransFLP method (Figure 1) is exemplified by three different approaches: I) the deletion of two adjacent genes encoding virulence determinants of V. cholerae (e.g., &Delta;ctxAB); II) the removal of a pathogenicity island (e.g., &Delta;VPI-1); and III) the integration of a T7 RNA polymerase-dependent promoter sequence upstream of a gene-of-interest, which subsequently allows its artificial expression in the respective strain background (e.g., T7-tfoX) (<st...

<ol>
	<li>Miller, V. L., Mekalanos, J. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+novel+suicide+vector+and+its+use+in+construction+of+insertion+mutations:+osmoregulation+of+outer+membrane+proteins+and+virulence+determinants+in+Vibrio+cholerae+requires+toxR.">A novel suicide vector and its use in construction of insertion mutations: osmoregulation of outer membrane proteins and virulence determinants in Vibrio cholerae requires toxR.</a> J. Bacteriol. 170, 2575-2583 (1988).</li><li>Hamilton, C. M., Aldea, M., Washburn, B. K., Babitzke, P., Kushner, S. R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=New+method+for+generating+deletions+and+gene+replacements+in+Escherichia+coli.">New method for generating deletions and gene replacements in Escherichia coli.</a> J. Bacteriol. 171, 4617-4622 (1989).</li><li>Kato, C., Ohmiya, R., Mizuno, T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+rapid+method+for+disrupting+genes+in+the+Escherichia+coli+genome.">A rapid method for disrupting genes in the Escherichia coli genome.</a> Biosci. Biotechnol. Biochem. 62, 1826-1829 (1998).</li><li>Donnenberg, M. S., Kaper, J. B. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Construction+of+an+eae+deletion+mutant+of+enteropathogenic+Escherichia+coli+by+using+a+positive-selection+suicide+vector.">Construction of an eae deletion mutant of enteropathogenic Escherichia coli by using a positive-selection suicide vector.</a> Infect. Immun. 59, 4310-4317 (1991).</li><li>De Souza Silva, O., Blokesch, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Genetic+manipulation+of+Vibrio+cholerae+by+combining+natural+transformation+with+FLP+recombination.">Genetic manipulation of Vibrio cholerae by combining natural transformation with FLP recombination.</a> Plasmid. 64, 186-195 (2010).</li><li>Meibom, K. L., Blokesch, M., Dolganov, N. A., Wu, C. -. Y., Schoolnik, G. K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Chitin+induces+natural+competence+in+Vibrio+cholerae.">Chitin induces natural competence in Vibrio cholerae.</a> Science. 310, 1824-1827 (2005).</li><li>Pollack-Berti, A., Wollenberg, M. S., Ruby, E. G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Natural+transformation+of+Vibrio+fischeri+requires+tfoX+and+tfoY.">Natural transformation of Vibrio fischeri requires tfoX and tfoY.</a> Environ. Microbiol. 12, 2302-2311 (2010).</li><li>Marvig, R. L., Blokesch, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Natural+transformation+of+Vibrio+cholerae+as+a+tool-optimizing+the+procedure.">Natural transformation of Vibrio cholerae as a tool-optimizing the procedure.</a> BMC Microbiol. 10, 155 (2010).</li><li>Blokesch, M., Schoolnik, G. K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Serogroup+Conversion+of+Vibrio+cholerae+in+Aquatic+Reservoirs.">Serogroup Conversion of Vibrio cholerae in Aquatic Reservoirs.</a> PLoS Pathog. 3, e81 (2007).</li><li>Cherepanov, P. P., Wackernagel, W. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Gene+disruption+in+Escherichia+coli:+TcR+and+KmR+cassettes+with+the+option+of+Flp-catalyzed+excision+of+the+antibiotic-resistance+determinant.">Gene disruption in Escherichia coli: TcR and KmR cassettes with the option of Flp-catalyzed excision of the antibiotic-resistance determinant.</a> Gene. 158, 9-14 (1995).</li><li>Sambrook, J., Fritsch, E. F., Maniatis, T., Ford, N., Nolan, C., Ferguson, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> Molecular Cloning: A laboratory manual. 1, (1989).</li><li>Reyes-Lamothe, R., Possoz, C., Danilova, O., Sherratt, D. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Independent+positioning+and+action+of+Escherichia+coli+replisomes+in+live+cells.">Independent positioning and action of Escherichia coli replisomes in live cells.</a> Cell. 133, 90-102 (2008).</li><li>Karaolis, D. K. R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+Vibrio+cholerae+pathogenicity+island+associated+with+epidemic+and+pandemic+strains.">A Vibrio cholerae pathogenicity island associated with epidemic and pandemic strains.</a> Proc. Natl. Acad. Sci. USA. 95, 3134-3139 (1998).</li><li>Ikeda, R. A., Ligman, C. M., Warshamana, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=T7+promoter+contacts+essential+for+promoter+activity+in+vivo.">T7 promoter contacts essential for promoter activity in vivo.</a> Nucleic Acids Res. 20, 2517-2524 (1992).</li><li>Pan, S. H., Malcolm, B. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Reduced+background+expression+and+improved+plasmid+stability+with+pET+vectors+in+BL21+(DE3).">Reduced background expression and improved plasmid stability with pET vectors in BL21 (DE3).</a> Biotechniques. 29, 1234-1238 (2000).</li><li>Faruque, S. M., Zhu, J., Asadulghani, M., Kamruzzaman, J. J., Mekalanos, <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Examination+of+diverse+toxin-coregulated+pilus-positive+Vibrio+cholerae+strains+fails+to+demonstrate+evidence+for+Vibrio+pathogenicity+island+phage.">Examination of diverse toxin-coregulated pilus-positive Vibrio cholerae strains fails to demonstrate evidence for Vibrio pathogenicity island phage.</a> Infect. Immun. 71, 2993-2999 (2003).</li><li>Joelsson, A., Liu, Z., Zhu, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Genetic+and+phenotypic+diversity+of+quorum-sensing+systems+in+clinical+and+environmental+isolates+of+Vibrio+cholerae.">Genetic and phenotypic diversity of quorum-sensing systems in clinical and environmental isolates of Vibrio cholerae.</a> Infect. Immun. 74, 1141-1147 (2006).</li><li>Heidelberg, J. F. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=DNA+sequence+of+both+chromosomes+of+the+cholera+pathogen+Vibrio+cholerae.">DNA sequence of both chromosomes of the cholera pathogen Vibrio cholerae.</a> Nature. 406, 477-483 (2000).</li></ol>

The TransFLP method described above and elsewhere5 has been extensively used in our laboratory. The kind of genetic manipulations that are feasible include amongst others: deletion of single genes and gene clusters, deletion of genomic islands (e.g., VPI-1), insertion of sequences upstream of a gene of interest (e.g., promoter sequences) and insertion of sequences at the end of a specific gene (e.g., encoding affinity tags).
An import prerequisite for Tran...

<table border="1">
<tbody>
 <tr>
 <td>Name of the reagent</td>
 <td>Company</td>
 <td>Catalogue number</td>
 <td>Comments</td>
 </tr>
 <tr>
 <td>Chitin flakes</td>
 <td>Sigma</td>
 <td>C9213</td>
 <td>Autoclaving required</td>
 </tr>
 <tr>
 <td>OPTIONAL: 			Micropulser (in case antibiotic cassette should be excised by 			Flp recombinase encoded on pBR-flp)</td>
 <td>Biorad</td>
 <td>165-2100</td>
 <td>Or comparable electroporators</td>
 </tr>
 </tbody>
</table>

transflp &#x2014; a method to genetically modify vibrio cholerae based on natural transformation and flp-recombination

Several methods are available to manipulate bacterial chromosomes1-3. Most of these protocols rely on the insertion of conditionally replicative plasmids (e.g. harboring pir-dependent or temperature-sensitive replicons1,2). These plasmids are integrated into bacterial chromosomes based on homology-mediated recombination. Such insertional mutants are often directly used in experimental settings. Alternatively, selection for plasmid excision followed by its loss can be performed, which for Gram-negative bacteria often relies on the counter-selectable levan sucrase enzyme encoded by the sacB gene4. The excision can either restore the pre-insertion genotype or result in an exchange between the chromosome and the plasmid-encoded copy of the modified gene. A disadvantage of this technique is that it is time-consuming. The plasmid has to be cloned first; it requires horizontal transfer into V. cholerae (most notably by mating with an E. coli donor strain) or artificial transformation of the latter; and the excision of the plasmid is random and can either restore the initial genotype or create the desired modification if no positive selection is exerted. Here, we present a method for rapid manipulation of the V. cholerae chromosome(s)5 (Figure 1). This TransFLP method is based on the recently discovered chitin-mediated induction of natural competence in this organism6 and other representative of the genus Vibrio such as V. fischeri7. Natural competence allows the uptake of free DNA including PCR-generated DNA fragments. Once taken up, the DNA recombines with the chromosome given the presence of a minimum of 250-500 bp of flanking homologous region8. Including a selection marker in-between these flanking regions allows easy detection of frequently occurring transformants.
This method can be used for different genetic manipulations of V. cholerae and potentially also other naturally competent bacteria. We provide three novel examples on what can be accomplished by this method in addition to our previously published study on single gene deletions and the addition of affinity-tag sequences5. Several optimization steps concerning the initial protocol of chitin-induced natural transformation6 are incorporated in this TransFLP protocol. These include among others the replacement of crab shell fragments by commercially available chitin flakes8, the donation of PCR-derived DNA as transforming material9, and the addition of FLP-recombination target sites (FRT)5. FRT sites allow site-directed excision of the selection marker mediated by the Flp recombinase10.

Representative results of the three examples are shown in Figures 4 to 6. The first approach aimed at deleting the neighboring genes ctxA and ctxB. Together they encode the major virulence factor of V. cholerae, cholera toxin. We designed oligonucleotides for the TransFLP method as described above and according to Figure 3. The parental strain, the intermediate strain harboring the FRT-flanked antibiotic resistance cassette at the original DNA locus of ctxA...

Watch this Scientific Journal Video about TransFLP Ã¢â‚¬â€ A Method to Genetically Modify Vibrio cholerae Based on Natural Transformation and FLP-recombination at JoVE.com

TransFLP ÃƒÂ¢Ã¢â€šÂ¬Ã¢â‚¬Â A Method to Genetically Modify Vibrio cholerae Based on Natural Transformation and FLP-recombination

A quick method to modify the genome of V. cholerae is described. These modifications include the deletion of single genes, gene clusters and genomic islands as well as the integration of short sequences (e.g. promoter elements or affinity-tag sequences). The method is based on the natural transformation and FLP-recombination.

TransFLP &#x2014; A Method to Genetically Modify Vibrio cholerae Based on Natural Transformation and FLP-recombination

Several methods are available to manipulate bacterial chromosomes1-3. Most of these protocols rely on the insertion of conditionally replicative plasmids ...

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