Expression of Salmonella typhimurium genes required for invasion is regulated by changes in DNA supercoiling

J. E. Galan, R. Curtiss

Research output: Contribution to journalArticle

205 Citations (Scopus)

Abstract

The ability to enter intestinal epithelial cells is an essential virulence factor of salmonellae. We have previously cloned a group of genes (invA, B, C, and D) that allow S. typhimurium to penetrate tissue culture cells (J.E. Galan and R. Curtiss III, Proc. Natl. Acad. Sci. USA 86:6383-6387, 1989). Transcriptional and translational cat and phoA fusions to invA (the proximal gene in the invABC operon) were constructed, and their expression was studied by measuring the levels of alkaline phosphatase or chloramphenicol acetyltransferase activity in mutants grown under different conditions. It was found that when strains containing the fusions were grown on media with high osmolarity, a condition known to increase DNA superhelicity, the level of invA transcription was approximately eightfold higher than that in strains grown on media with low osmolarity. The osmoinducibility of invA was independent of ompR, which controls the osmoinducibility of other genes. Strains grown in high-osmolarity media in the presence of subinhibitory concentrations of gyrase inhibitors (novobiocin or coumermycin A1), which reduce the level of DNA supercoiling, showed reduced expression of invA. Nevertheless, invA was poorly expressed in topA mutants of S. typhimurium, which have increased DNA superhelicity. In all cases, the differential expression of the invasion genes was correlated with the ability of S. typhimurium to penetrate tissue culture cells. These results taken together indicate that expression of S. typhimurium invasion genes is affected by changes in DNA supercoiling and suggest that this may represent a way in which this organism regulates the expression of these genes.

Original languageEnglish (US)
Pages (from-to)1879-1885
Number of pages7
JournalInfection and Immunity
Volume58
Issue number6
StatePublished - 1990
Externally publishedYes

Fingerprint

Salmonella typhimurium
Osmolar Concentration
DNA
Genes
Cell Culture Techniques
Novobiocin
Gene Expression
Chloramphenicol O-Acetyltransferase
Virulence Factors
Operon
Salmonella
Alkaline Phosphatase
Cats
Epithelial Cells

ASJC Scopus subject areas

  • Immunology

Cite this

Expression of Salmonella typhimurium genes required for invasion is regulated by changes in DNA supercoiling. / Galan, J. E.; Curtiss, R.

In: Infection and Immunity, Vol. 58, No. 6, 1990, p. 1879-1885.

Research output: Contribution to journalArticle

@article{e9c66abc7c40429385a59157b3beda19,
title = "Expression of Salmonella typhimurium genes required for invasion is regulated by changes in DNA supercoiling",
abstract = "The ability to enter intestinal epithelial cells is an essential virulence factor of salmonellae. We have previously cloned a group of genes (invA, B, C, and D) that allow S. typhimurium to penetrate tissue culture cells (J.E. Galan and R. Curtiss III, Proc. Natl. Acad. Sci. USA 86:6383-6387, 1989). Transcriptional and translational cat and phoA fusions to invA (the proximal gene in the invABC operon) were constructed, and their expression was studied by measuring the levels of alkaline phosphatase or chloramphenicol acetyltransferase activity in mutants grown under different conditions. It was found that when strains containing the fusions were grown on media with high osmolarity, a condition known to increase DNA superhelicity, the level of invA transcription was approximately eightfold higher than that in strains grown on media with low osmolarity. The osmoinducibility of invA was independent of ompR, which controls the osmoinducibility of other genes. Strains grown in high-osmolarity media in the presence of subinhibitory concentrations of gyrase inhibitors (novobiocin or coumermycin A1), which reduce the level of DNA supercoiling, showed reduced expression of invA. Nevertheless, invA was poorly expressed in topA mutants of S. typhimurium, which have increased DNA superhelicity. In all cases, the differential expression of the invasion genes was correlated with the ability of S. typhimurium to penetrate tissue culture cells. These results taken together indicate that expression of S. typhimurium invasion genes is affected by changes in DNA supercoiling and suggest that this may represent a way in which this organism regulates the expression of these genes.",
author = "Galan, {J. E.} and R. Curtiss",
year = "1990",
language = "English (US)",
volume = "58",
pages = "1879--1885",
journal = "Infection and Immunity",
issn = "0019-9567",
publisher = "American Society for Microbiology",
number = "6",

}

TY - JOUR

T1 - Expression of Salmonella typhimurium genes required for invasion is regulated by changes in DNA supercoiling

AU - Galan, J. E.

AU - Curtiss, R.

PY - 1990

Y1 - 1990

N2 - The ability to enter intestinal epithelial cells is an essential virulence factor of salmonellae. We have previously cloned a group of genes (invA, B, C, and D) that allow S. typhimurium to penetrate tissue culture cells (J.E. Galan and R. Curtiss III, Proc. Natl. Acad. Sci. USA 86:6383-6387, 1989). Transcriptional and translational cat and phoA fusions to invA (the proximal gene in the invABC operon) were constructed, and their expression was studied by measuring the levels of alkaline phosphatase or chloramphenicol acetyltransferase activity in mutants grown under different conditions. It was found that when strains containing the fusions were grown on media with high osmolarity, a condition known to increase DNA superhelicity, the level of invA transcription was approximately eightfold higher than that in strains grown on media with low osmolarity. The osmoinducibility of invA was independent of ompR, which controls the osmoinducibility of other genes. Strains grown in high-osmolarity media in the presence of subinhibitory concentrations of gyrase inhibitors (novobiocin or coumermycin A1), which reduce the level of DNA supercoiling, showed reduced expression of invA. Nevertheless, invA was poorly expressed in topA mutants of S. typhimurium, which have increased DNA superhelicity. In all cases, the differential expression of the invasion genes was correlated with the ability of S. typhimurium to penetrate tissue culture cells. These results taken together indicate that expression of S. typhimurium invasion genes is affected by changes in DNA supercoiling and suggest that this may represent a way in which this organism regulates the expression of these genes.

AB - The ability to enter intestinal epithelial cells is an essential virulence factor of salmonellae. We have previously cloned a group of genes (invA, B, C, and D) that allow S. typhimurium to penetrate tissue culture cells (J.E. Galan and R. Curtiss III, Proc. Natl. Acad. Sci. USA 86:6383-6387, 1989). Transcriptional and translational cat and phoA fusions to invA (the proximal gene in the invABC operon) were constructed, and their expression was studied by measuring the levels of alkaline phosphatase or chloramphenicol acetyltransferase activity in mutants grown under different conditions. It was found that when strains containing the fusions were grown on media with high osmolarity, a condition known to increase DNA superhelicity, the level of invA transcription was approximately eightfold higher than that in strains grown on media with low osmolarity. The osmoinducibility of invA was independent of ompR, which controls the osmoinducibility of other genes. Strains grown in high-osmolarity media in the presence of subinhibitory concentrations of gyrase inhibitors (novobiocin or coumermycin A1), which reduce the level of DNA supercoiling, showed reduced expression of invA. Nevertheless, invA was poorly expressed in topA mutants of S. typhimurium, which have increased DNA superhelicity. In all cases, the differential expression of the invasion genes was correlated with the ability of S. typhimurium to penetrate tissue culture cells. These results taken together indicate that expression of S. typhimurium invasion genes is affected by changes in DNA supercoiling and suggest that this may represent a way in which this organism regulates the expression of these genes.

UR - http://www.scopus.com/inward/record.url?scp=0025374683&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=0025374683&partnerID=8YFLogxK

M3 - Article

C2 - 2160435

AN - SCOPUS:0025374683

VL - 58

SP - 1879

EP - 1885

JO - Infection and Immunity

JF - Infection and Immunity

SN - 0019-9567

IS - 6

ER -