A new chromosomal locus associated with gut-modulated phenotypes in Salmonella enterica serotype typhimurium.
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(pHC20-2), 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(pHC20-2) 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(pHC20 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 pHC20-2 encodes a pleiotropic regulator of genes involved in gastro-enteritic virulence and adaptation to the in-vivo gut environment. pHC20-2 mapped at c. centisome 25 on the salmonella chromosome close to, but distinct from, SPI-5.
Robey
Marianne
M
Molecular Microbiology Group, School of Biosciences, University of Birmingham, Edgbaston, Birmingham B15 2TT.
Morgan
Eirwen
E
Molecular Microbiology Group, School of Biosciences, University of Birmingham, Edgbaston, Birmingham B15 2TT.
Lodge
Julia M
JM
Molecular Microbiology Group, School of Biosciences, University of Birmingham, Edgbaston, Birmingham B15 2TT.
Bolton
Alex J
AJ
Molecular Microbiology Group, School of Biosciences, University of Birmingham, Edgbaston, Birmingham B15 2TT.
Martin
Gillian D
GD
Molecular Microbiology Group, School of Biosciences, University of Birmingham, Edgbaston, Birmingham B15 2TT.
Brown
Nigel L
NL
Molecular Microbiology Group, School of Biosciences, University of Birmingham, Edgbaston, Birmingham B15 2TT.
Stephen
John
J
Molecular Microbiology Group, School of Biosciences, University of Birmingham, Edgbaston, Birmingham B15 2TT.
D018829:Adhesins, Bacterial; D000818:Animals; D001426:Bacterial Proteins / Q000096:biosynthesis / Q000235:genetics; D018938:Caco-2 Cells; D002876:Chromosomes, Bacterial; D003360:Cosmids; D004591:Electrophoresis, Polyacrylamide Gel; D005408:Flagellin / Q000096:biosynthesis / Q000235:genetics; D006801:Humans; D007082:Ileum / Q000382:microbiology*; D008854:Microscopy, Electron; D009924:Organ Culture Techniques; D018272:Porins / Q000096:biosynthesis / Q000235:genetics; D011817:Rabbits; D011995:Recombination, Genetic; D012486:Salmonella typhimurium / Q000235:genetics* / Q000472:pathogenicity / Q000648:ultrastructure; D017422:Sequence Analysis, DNA
D018829:Adhesins, Bacterial; D001426:Bacterial Proteins; D018272:Porins; C053476:invasin, Yersinia; D005408:Flagellin