HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via CrossRef Citing Articles via Google Scholar Google Scholar Articles by ROBEY, M. Articles by STEPHEN, J. Search for Related Content PubMed PubMed Citation Articles by ROBEY, M. Articles by STEPHEN, J. Agricola Articles by ROBEY, M. Articles by STEPHEN, J.

A new chromosomal locus associated with gut-modulated phenotypes in Salmonella enterica serotype Typhimurium

Molecular Microbiology Group, School of Biosciences, University of Birmingham, Edgbaston, Birmingham B15 2TT

Corresponding author: Dr J. Stephen (e-mail: J.Stephen@ bham.ac.uk).

Received 29 April 2001; revised version received 31 July 2001; accepted 2 Aug. 2001.

Abstract

A cosmid DNA library had been constructed previously from 40-kb fragments of genomic DNA from a virulent invasive strain of Salmonella enterica serotype Typhimurium (TML) in an avirulent hypo-invasive Typhimurium strain (LT7). Selection of invasive clones from the library was attempted by iterative passage through a rabbit ileal organ culture. After the fourth passage, a clone, designated LT7(pHC20uu.2), was isolated. Exposure to both gut tissue and Caco-2 cells enhanced the growth, invasiveness for gut and Caco-2 cells, and flagellin expression of LT7(pHC20uu.2) although its invasiveness was less than that of strain TML. Expression of appendages (surface structures c. 60–70 nm diameter) was shown to play a role in but not to confer invasiveness, and was demonstrated in the absence of direct contact with eukaryotic cells. Exposure to gut tissue also affected the expression of several outer-membrane proteins (OMPs) in all four Salmonella strains – TML, LT7, LT7(pHC79), LT7(pHC20uu.2) – used in this work. As the genes involved in flagella, invasin and porin expression are distributed around the salmonella chromosome, it is possible that pHC20uu.2 encodes a pleiotropic regulator of genes involved in gastro-enteritic virulence and adaptation to the in-vivo gut environment. pHC20uu.2 mapped at c. centisome 25 on the salmonella chromosome close to, but distinct from, SPI-5.