The Gram-negative Tol-Pal system of envelope proteins plays a key role in maintaining outer membrane integrity and contributes to the virulence of several pathogens. We have investigated the role of one of these proteins, TolA, in the biology of Salmonella enterica serovar Typhimurium. Deletion of tolA rendered strain SL1344 more susceptible to killing by bile and human serum. In addition the mutant had impaired membrane integrity and displayed alterations in LPS production. The tolA mutant was highly attenuated in mouse infections via the oral and intravenous routes. Importantly, each phenotype displayed by the mutant was complemented by provision of tolAin trans. The tolA gene therefore contributes to virulence, membrane integrity, LPS production and bile and serum resistance in S. enterica serovar Typhimurium SL1344. Finally, immunization with the tolA mutant provided significant protection against subsequent challenge with wild-type SL1344. The Tol-Pal system is therefore a potential target in the development of novel attenuated live vaccines against Salmonella and other Gram-negative pathogens.
BoweF.,
LippsC. J.,
TsolisR. M.,
GroismanE.,
HeffronF.,
KustersJ. G.1998; At least four percent of the Salmonella typhimurium genome is required for fatal infection of mice. Infect Immun 66:3372–3377
BullasL. R.,
RyuJ. I.1983; Salmonella typhimurium LT2 strains which are r− m+ for all three chromosomally located systems of DNA restriction and modification. J Bacteriol 156:471–474
FieldsP. I.,
GroismanE. A.,
HeffronF.1989; A Salmonella locus that controls resistance to microbicidal proteins from phagocytic cells. Science 243:1059–1062
FortneyK. R.,
YoungR. S.,
BauerM. E.,
KatzB. P.,
HoodA. F.,
MunsonR. S.Jr,
SpinolaS. M.2000; Expression of peptidoglycan-associated lipoprotein is required for virulence in the human model of Haemophilus ducreyi infection. Infect Immun 68:6441–6448
GasparJ. A.,
ThomasJ. A.,
MaroldaC. L.,
ValvanoM. A.2000; Surface expression of O-specific lipopolysaccharide in Escherichia coli requires the function of the TolA protein. Mol Microbiol 38:262–275
HellmanJ.,
RobertsJ. D.Jr,
TehanM. M.,
AllaireJ. E.,
WarrenH. S.2002; Bacterial peptidoglycan-associated lipoprotein is released into the bloodstream in gram-negative sepsis and causes inflammation and death in mice. J Biol Chem 277:14274–14280
JonesB. D.,
NicholsW. A.,
GibsonB. W.,
SunshineM. G.,
ApicellaM. A.1997; Study of the role of the htrB gene in Salmonella typhimurium virulence. Infect Immun 65:4778–4783
LazzaroniJ. C.,
GermonP.,
RayM. C.,
VianneyA.1999; The Tol proteins of Escherichia coli and their involvement in the uptake of biomolecules and outer membrane stability. FEMS Microbiol Lett 177:191–197
LazzaroniJ.-C.,
DubuissonJ.-F.,
VianneyA.2002; The Tol proteins of Escherichia coli and their involvement in the translocation of group A colicins. Biochimie 84:391–397
LloubesR.,
CascalesE.,
WalburgerA.,
BouveretE.,
LazdunskiC.,
BernadacA.,
JournetL.2001; The Tol-Pal proteins of the Escherichia coli cell envelope: an energized system required for outer membrane integrity?. Res Microbiol 152:523–529
MoE.,
PetersS. E.,
WillersC.,
MaskellD. J.,
CharlesI. G.2006; Single, double and triple mutants of Salmonella enterica serovar TyphimuriumdegP (htrA), degQ ( hhoA) and degS ( hhoB) have diverse phenotypes on exposure to elevated temperature and their growth in vivo is attenuated to different extents. Microb Pathog 41:174–182
MurrayG. L.,
AttridgeS. R.,
MoronaR.2003; Regulation of Salmonella typhimurium lipopolysaccharide O antigen chain length is required for virulence; identification of FepE as a second Wzz. Mol Microbiol 47:1395–1406
MurrayG. L.,
AttridgeS. R.,
MoronaR.2006; Altering the length of the lipopolysaccharide O antigen has an impact on the interaction of Salmonella enterica serovar Typhimurium with macrophages and complement. J Bacteriol 188:2735–2739
NagyG.,
DobrindtU.,
HackerJ.,
EmodyL.2004; Oral immunization with an rfaH mutant elicits protection against salmonellosis in mice. Infect Immun 72:4297–4301
OhnoA.,
IsiiY.,
TatedaK.,
MatumotoT.,
MiyazakiS.,
YokotaS.,
YamaguchiK.1995; Role of LPS length in clearance rate of bacteria from the bloodstream in mice. Microbiology 141:2749–2756
ProutyA. M.,
Van VelkinburghJ. C.,
GunnJ. S.2002; Salmonella enterica serovar Typhimurium resistance to bile: identification and characterization of the tolQRA cluster. J Bacteriol 184:1270–1276
SunT. P.,
WebsterR. E.1987; Nucleotide sequence of a gene cluster involved in entry of E colicins and single-stranded DNA of infecting filamentous bacteriophages into Escherichia coli
. J Bacteriol 169:2667–2674
ThomsenL. E.,
ChadfieldM. S.,
BisphamJ.,
WallisT. S.,
OlsenJ. E.,
IngmerH.2003; Reduced amounts of LPS affect both stress tolerance and virulence of Salmonella enterica serovar Dublin. FEMS Microbiol Lett 228:225–231
VinesE. D.,
MaroldaC. L.,
BalachandranA.,
ValvanoM. A.2005; Defective O-antigen polymerization in tolA and pal mutants of Escherichia coli in response to extracytoplasmic stress. J Bacteriol 187:3359–3368