Integration of minitransposons for expression of the Escherichia coli elt genes at a preferred site in Salmonella typhimurium identifies a novel putative fimbrial locus |
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Authors: | M Brocchi M Giuseppina Covone Emanuela Palla C L Galeotti |
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Institution: | (1) Immunobiology Research Institute Siena, Department of Molecular Biology, Chiron Vaccines, Via Fiorentina 1, I-53100 Siena, Italy e-mail: galeotti@iris02.biocine.it Tel. +39-577-243485; Fax +39-577-243564, IT |
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Abstract: | An asd-complementing mini-Tn5 transposon was constructed for random insertion of the Escherichia coli LT enterotoxin genes (elt) into the genome of Δasd attenuated strains of Salmonella typhimurium. Transfer of the minitransposon to different S. typhimurium strains resulted in random integration only in strain χ4072, while in strain χ3987, which harbours the virulence plasmid,
over 20% of the insertions occurred at the same site. Expression of elt was found to be highest in Salmonella isolates carrying the mini-Tn5 integrated at the preferred site, which was mapped to an uncharacterised region of the virulence plasmid. Sequence analysis
of the integration site showed that it lies within an open reading frame with sequence similarity to E. coli leuO and contiguous to a novel fimbrial locus.
Received: 26 August 1998 / Accepted: 9 November 1998 |
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Keywords: | Salmonella typhimurium Minitransposons LT enterotoxin Expression Fimbriae |
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