scholarly journals Altering the Length of the Lipopolysaccharide O Antigen Has an Impact on the Interaction of Salmonella enterica Serovar Typhimurium with Macrophages and Complement

2006 ◽  
Vol 188 (7) ◽  
pp. 2735-2739 ◽  
Author(s):  
Gerald L. Murray ◽  
Stephen R. Attridge ◽  
Renato Morona
Keyword(s):  
Vibrio Cholerae ◽  
Salmonella Enterica ◽  
Double Mutant ◽  
Salmonella Enterica Serovar Typhimurium ◽  
Shigella Flexneri ◽  
O Antigen ◽  
Repeat Units ◽  
Complement Resistance ◽  
Serovar Typhimurium ◽  
First Time

ABSTRACT A panel of isogenic Salmonella enterica serovar Typhimurium strains that vary only in the length of the O antigen was constructed through complementation of a wzz double mutant (displaying unregulated O-antigen length) with one of two homologous (wzz ST and wzz fepE) or three heterologous (wzz O139 of Vibrio cholerae and wzz SF and wzz pHS-2 of Shigella flexneri) wzz genes. Each gene was functional in the S. enterica serovar Typhimurium host and specified production of O-antigen polymers with lengths typical of those synthesized by the donor bacteria (ranging from 2 to >100 O-antigen repeat units). By use of this panel of strains, it was found that O-antigen length influences invasion/uptake by macrophage cells; this is the first time this has been shown with Salmonella. O-antigen length was confirmed to be related to complement resistance, with a minimum protective length of >4 and <15 repeat units. O antigen of 16 to 35 repeat units was found to activate complement more efficiently than other lengths, but this was unrelated to complement resistance. No evidence was found to suggest that modifying the length of the O-antigen polymer affected expression of the O1, O4, or O5 antigenic factors.

scholarly journals A Salmonella enterica Serovar Typhimurium Succinate Dehydrogenase/Fumarate Reductase Double Mutant Is Avirulent and Immunogenic in BALB/c Mice

2007 ◽  
Vol 76 (3) ◽  
pp. 1128-1134 ◽  
Author(s):  
Regino Mercado-Lubo ◽  
Eric J. Gauger ◽  
Mary P. Leatham ◽  
Tyrrell Conway ◽  
Paul S. Cohen
Keyword(s):  
Succinate Dehydrogenase ◽  
Salmonella Enterica ◽  
Double Mutant ◽  
Wild Type Strain ◽  
Salmonella Enterica Serovar Typhimurium ◽  
Tca Cycle ◽  
Fumarate Reductase ◽  
Subsequent Infection ◽  
The Tca Cycle ◽  
Serovar Typhimurium

ABSTRACT Previously we showed that the tricarboxylic acid (TCA) cycle operates as a full cycle during Salmonella enterica serovar Typhimurium SR-11 peroral infection of BALB/c mice (M. Tchawa Yimga et al., Infect. Immun. 74:1130-1140, 2006). The evidence was that a ΔsucCD mutant (succinyl coenzyme A [succinyl-CoA] synthetase), which prevents the conversion of succinyl-CoA to succinate, and a ΔsdhCDA mutant (succinate dehydrogenase), which blocks the conversion of succinate to fumarate, were both attenuated, whereas an SR-11 ΔaspA mutant (aspartase) and an SR-11 ΔfrdABCD mutant (fumarate reductase), deficient in the ability to run the reductive branch of the TCA cycle, were fully virulent. In the present study, evidence is presented that a serovar Typhimurium SR-11 ΔfrdABCD ΔsdhCDA double mutant is avirulent in BALB/c mice and protective against subsequent infection with the virulent serovar Typhimurium SR-11 wild-type strain via the peroral route and is highly attenuated via the intraperitoneal route. These results suggest that fumarate reductase, which normally runs in the reductive pathway in the opposite direction of succinate dehydrogenase, can replace it during infection by running in the same direction as succinate dehydrogenase in order to run a full TCA cycle in an SR-11 ΔsdhCDA mutant. The data also suggest that the conversion of succinate to fumarate plays a key role in serovar Typhimurium virulence. Moreover, the data raise the possibility that S. enterica ΔfrdABCD ΔsdhCDA double mutants and ΔfrdABCD ΔsdhCDA double mutants of other intracellular bacterial pathogens with complete TCA cycles may prove to be effective live vaccine strains for animals and humans.

scholarly journals The enzyme phosphoglucomutase (Pgm) is required by Salmonella enterica serovar Typhimurium for O-antigen production, resistance to antimicrobial peptides and in vivo fitness

Microbiology ◽  
2009 ◽  
Vol 155 (10) ◽  
pp. 3403-3410 ◽  
Author(s):  
G. K. Paterson ◽  
D. B. Cone ◽  
S. E. Peters ◽  
D. J. Maskell
Keyword(s):  
Antimicrobial Peptides ◽  
Salmonella Enterica ◽  
Salmonella Enterica Serovar Typhimurium ◽  
Live Attenuated Vaccine ◽  
Antigen Production ◽  
O Antigen ◽  
Serovar Typhimurium

The enzyme phosphoglucomutase (Pgm) catalyses the interconversion of glucose 1-phosphate and glucose 6-phosphate and contributes to glycolysis and the generation of sugar nucleotides for biosynthesis. To assess the role of this enzyme in the biology of the pathogen Salmonella enterica serovar Typhimurium we have characterized a pgm deletion mutant in strain SL1344. Compared to SL1344, SL1344 pgm had impaired growth in vitro, was deficient in the ability to utilize galactose as a carbon source and displayed reduced O-antigen polymer length. The mutant was also more susceptible to antimicrobial peptides and showed decreased fitness in the mouse typhoid model. The in vivo phenotype of SL1344 pgm indicated a role for pgm in the early stages of infection, most likely through deficient O-antigen production. Although pgm mutants in other pathogens have potential as live attenuated vaccine strains, SL1344 pgm was not sufficiently attenuated for such use.

Identification of a region in Shigella flexneri WzyB disrupting the interaction with Wzz pHS2

2021 ◽  
Author(s):  
Vincenzo Leo ◽  
Min Yan Teh ◽  
Elizabeth N.H Tran ◽  
Renato Morona
Keyword(s):  
Shigella Flexneri ◽  
Direct Interaction ◽  
Site Directed Mutagenesis ◽  
Physical Interaction ◽  
Significant Implication ◽  
O Antigen ◽  
Repeat Units ◽  
Inner Membrane Protein ◽  
First Time ◽  
Dependent Pathway

Shigella flexneri can synthesise polysaccharide chains having complex sugars and a regulated number of repeating units. S. flexneri lipopolysaccharide O antigen (Oag) is synthesised by the Wzy-dependent pathway which is the most common pathway used in bacteria for polysaccharide synthesis. The inner membrane protein WzyB polymerizes the Oag repeat units into chains, while the polysaccharide co-polymerases WzzB and Wzz pHS2 determine the average number of repeat units or “the modal length”, termed short-type and very long-type. Our data show for the first time a direct interaction between WzyB and Wzz pHS2 , with and without the use of the chemical cross-linker dithiobis (succinimidyl propionate) (DSP). Additionally mutations, generated via random and site directed mutagenesis, identify a region of WzyB that caused diminished function and significantly decreased very-long Oag chain polymerisation, and that affected the aforementioned interaction. These results provide insight into the mechanisms underlying the regulation of Oag biosynthesis. Importance Complex polysaccharide chains are synthesised by bacteria, usually at a regulated number of repeating units, which has broad implications for bacterial pathogenesis. One example is the O antigen (Oag) component of lipopolysaccharide that is predominantly synthesised by the Wzy-dependent pathway. Our findings show for the first time a direct physical interaction between WzyB and Wzz pHS2 . Additionally, a set of Wzy mutant constructs were generated revealing a proposed active site/switch region involved in the activity of WzyB and the physical interaction with Wzz pHS2 . Combined, these findings further the understanding of the Wzy-dependent pathway. The identification of a novel interaction with the polysacchraride co-polymerase Wzz pHS2, and the region of WzyB that is involved in this aforementioned interaction and its impact on WzyB Oag synthesis activity, have significant implication for the prevention/treatment of bacterial diseases, and discovery of novel biotechnologies.

scholarly journals O-Antigen-Negative Salmonella enterica Serovar Typhimurium Is Attenuated in Intestinal Colonization but Elicits Colitis in Streptomycin-Treated Mice

2009 ◽  
Vol 77 (6) ◽  
pp. 2568-2575 ◽  
Author(s):  
Karin Ilg ◽  
Kathrin Endt ◽  
Benjamin Misselwitz ◽  
Bärbel Stecher ◽  
Markus Aebi ◽  
...  
Keyword(s):  
Salmonella Enterica ◽  
Salmonella Enterica Serovar Typhimurium ◽  
Intestinal Inflammation ◽  
Polymyxin B ◽  
Major Constituent ◽  
O Antigen ◽  
Peptide Mimic ◽  
Serovar Typhimurium ◽  
Important Virulence Factor

ABSTRACT Lipopolysaccharide (LPS) is a major constituent of the outer membrane and an important virulence factor of Salmonella enterica subspecies 1 serovar Typhimurium (serovar Typhimurium). To evaluate the role of LPS in eliciting intestinal inflammation in streptomycin-treated mice, we constructed an O-antigen-deficient serovar Typhimurium strain through deletion of the wbaP gene. The resulting strain was highly susceptible to human complement activity and the antimicrobial peptide mimic polymyxin B. Furthermore, it showed a severe defect in motility and an attenuated phenotype in a competitive mouse infection experiment, where the ΔwbaP strain (SKI12) was directly compared to wild-type Salmonella. Nevertheless, the ΔwbaP strain (SKI12) efficiently invaded HeLa cells in vitro and elicited acute intestinal inflammation in streptomycin-pretreated mice. Our experiments prove that the presence of complete LPS is not essential for in vitro invasion or for triggering acute colitis.

scholarly journals Use of Lambda Phage S and R Gene Products in an Inducible Lysis System for Vibrio cholerae- and Salmonella enterica Serovar Typhimurium-Based DNA Vaccine Delivery Systems

2000 ◽  
Vol 68 (2) ◽  
pp. 986-989 ◽  
Author(s):  
Vivek Jain ◽  
John J. Mekalanos
Keyword(s):  
Vibrio Cholerae ◽  
Dna Vaccine ◽  
Salmonella Enterica ◽  
Salmonella Enterica Serovar Typhimurium ◽  
Dna Delivery ◽  
Lambda Phage ◽  
Regulated Expression ◽  
Mutant Strains ◽  
Serovar Typhimurium ◽  
Integrity Of Dna

ABSTRACT Novel methods for adapting DNA vaccine technology to the prevention of mucosal diseases are greatly needed. Here we show that regulated expression of phage lambda lysis genes S and R causes dramatic lysis of both Vibrio cholerae and Salmonella entericaserovar Typhimurium cells with concomitant release of plasmid DNA into the surrounding media. We also used single and double DNase mutant strains to show that secreted V. cholerae DNases can adversely affect the integrity of DNA molecules released upon lysis. These results suggest that incorporation of lambda SR-mediated lysis constructs and DNA stabilizing mutations into candidate live attenuated bacterial vaccines offers a promising approach for the development of effective mucosal DNA delivery vectors for humans.

The PmrA/PmrB regulatory system controls the expression of the wzzfepE gene involved in the O-antigen synthesis of Salmonella enterica serovar Typhimurium

Microbiology ◽  
2011 ◽  
Vol 157 (9) ◽  
pp. 2515-2521 ◽  
Author(s):  
María de las Mercedes Pescaretti ◽  
Fabián E. López ◽  
Roberto D. Morero ◽  
Mónica A. Delgado
Keyword(s):  
Salmonella Enterica ◽  
Salmonella Enterica Serovar Typhimurium ◽  
Regulatory System ◽  
Polymyxin B ◽  
Degree Of Polymerization ◽  
O Antigen ◽  
Functional Differences ◽  
Serovar Typhimurium ◽  
Direct Binding

The degree of polymerization of O-antigen from Salmonella enterica serovar Typhimurium is controlled by the products of the wzzs t and wzzfepE genes. In the present study we investigated the role of the PmrA/PmrB regulatory system in wzzfepE transcription. We report that the direct binding of the PmrA regulator to a specific promoter site induces the expression of the wzzfepE gene. This effect increases the amount of very long (VL) O-antigen, which is required for the resistance of Salmonella to serum human complement and polymyxin B, and for the replication of the bacteria within macrophages. The results obtained here highlight functional differences between WzzfepE and Wzzst, although the genes for both proteins are regulated in a PmrA-dependent way.

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