Affiliation:
1. Institut National de la Recherche Agronomique, Centre de Tours-Nouzilly, Infectiologie Animale et Santé Publique, 37380 Nouzilly, France
2. Institute for Animal Health, Compton Laboratory, Division of Environmental Microbiology Newbury, Berkshire RG20 7NN, United Kingdom
Abstract
ABSTRACT
Salmonella enterica
, like many gram-negative pathogens, uses type three secretion systems (TTSS) to infect its hosts. The three TTSS of
Salmonella
, namely, TTSS-1, TTSS-2, and flagella, play a major role in the virulence of this bacterium, allowing it to cross the intestinal barrier and to disseminate systemically. Previous data from our laboratory have demonstrated the involvement of the chromosomal region harboring the
yfgL
,
engA
, and
yfgJ
open reading frames in
S. enterica
serovar Enteritidis virulence. Using microarray analysis and real-time reverse transcription-PCR after growth of bacterial cultures favorable for either TTSS-1 or TTSS-2 expression, we show in this study that the deletion in
S. enterica
serovar Enteritidis of
yfgL
, encoding an outer membrane lipoprotein, led to the transcriptional down-regulation of most
Salmonella
pathogenicity island 1 (SPI-1), SPI-2, and flagellar genes encoding the TTSS structural proteins and effector proteins secreted by these TTSS. In line with these results, the virulence of the Δ
yfgL
mutant was greatly attenuated in mice. Moreover, even if YfgL is involved in the assembly of outer membrane proteins, the regulation of TTSS expression observed was not due to an inability of the Δ
yfgL
mutant to assemble TTSS in its membrane. Indeed, when we forced the transcription of SPI-1 genes by constitutively expressing HilA, the secretion of the TTSS-1 effector protein SipA was restored in the culture supernatant of the mutant. These results highlight the crucial role of the outer membrane lipoprotein YfgL in the expression of all
Salmonella
TTSS and, thus, in the virulence of
Salmonella
. Therefore, this outer membrane protein seems to be a privileged target for fighting
Salmonella
.
Publisher
American Society for Microbiology
Subject
Infectious Diseases,Immunology,Microbiology,Parasitology
Cited by
42 articles.
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