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The role of a stress‐response protein in Salmonella typhimurium virulence
Author(s) -
Johnson K.,
Charles I.,
Dougan G.,
Pickard D.,
O'Gaora P.,
Costa G.,
Ali T.,
Miller I.,
Hormaeche C.
Publication year - 1991
Publication title -
molecular microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.857
H-Index - 247
eISSN - 1365-2958
pISSN - 0950-382X
DOI - 10.1111/j.1365-2958.1991.tb02122.x
Subject(s) - biology , virulence , mutant , escherichia coli , periplasmic space , transposon mutagenesis , salmonella , mutagenesis , gene , heat shock protein , open reading frame , microbiology and biotechnology , transposable element , genetics , peptide sequence , bacteria
Summary We recently described the use of selective transposon mutagenesis to generate a series of a virulent mutants of a pathogenic strain of Salmonella typhimurium. Cloning and sequencing of the insertion sites from two of these mutants reveals that both have identical locations within an open reading frame that is highly homologous to a gene, htrA , encoding a heat‐shock protein in Escherichia coli. DNA sequence analysis of S. typhimurium htrA reveals the presence of a gene capable of encoding a protein with a calculated M r of 49316 that has 88.7% protein:protein homology with its E. coli counterpart. In E. coli , lesions in this gene, also known as degP , reduce proteolytic degradation of aberrant periplasmic proteins. Characteristics of the S. typhimurium htrA mutants, 046 and 014, in vivo and in vitro suggested that they are avirulent because of impaired ability to survive and/or replicate in host tissues. In vitro , the S. typhimurium htrA mutants 046 and 014 are not temperature‐sensitive but were found to be more susceptible to oxidative stress than the parent, suggesting that they may be less able to withstand oxidative killing within macrophages.