scholarly journals Coordinated expression and immunogenicity of an outer membrane protein from Salmonella enterica serovar Typhi under iron limitation, oxidative stress and anaerobic conditions

2005 ◽  
Vol 13 (3) ◽  
pp. 303-312 ◽  
Author(s):  
V. Chanana ◽  
S. Majumdar ◽  
P. Ray ◽  
M. Sharma ◽  
P. Rishi
Keyword(s):  
Oxidative Stress ◽  
Membrane Protein ◽  
Outer Membrane ◽  
Outer Membrane Protein ◽  
Salmonella Enterica ◽  
Iron Limitation ◽  
Anaerobic Conditions ◽  
Salmonella Enterica Serovar Typhi ◽  
Coordinated Expression

scholarly journals Identification of an Iron-Regulated Hemin-Binding Outer Membrane Protein, HupO, in Vibrio fluvialis: Effects on Hemolytic Activity and the Oxidative Stress Response

2005 ◽  
Vol 73 (2) ◽  
pp. 722-729 ◽  
Author(s):  
Sun-Hee Ahn ◽  
Jeong-Hyun Han ◽  
Jong-Hee Lee ◽  
Kee-Jai Park ◽  
In-Soo Kong
Keyword(s):  
Oxidative Stress ◽  
Membrane Protein ◽  
Outer Membrane ◽  
Outer Membrane Protein ◽  
Hemolytic Activity ◽  
Lethal Dose ◽  
Sodium Dodecyl ◽  
Watery Diarrhea ◽  
Wild Type ◽  
Vibrio Fluvialis

ABSTRACT In pathogenic bacteria, iron acquisition is important for colonization and proliferation in the host under iron-limited conditions. The ability of Vibrio spp. to acquire iron is often critical to their virulence, causing gastroenteritis or excessive watery diarrhea in humans. In the study described here, we cloned the 2,100-bp heme utilization protein gene hupO in Vibrio fluvialis. HupO had high homology to iron-regulated outer membrane receptor proteins in Vibrio sp. and contained motifs that are common to bacterial heme receptors, including a consensus TonB box, a FRAP domain, and an NPNL domain. To characterize the hemin-binding activity of HupO, we purified the recombinant HupO protein (rHupO) from Escherichia coli by using an overexpression system. HupO was found to bind to hemin but not to hemoglobin. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis and Western blotting demonstrated that the 77-kDa outer membrane protein HupO of V. fluvialis was induced under iron-restricted conditions. We constructed a hupO mutant, HP1, to investigate the biochemical function of HupO in V. fluvialis. The hemolytic activity of HP1 was reduced compared to that of wild-type cells and, when exposed to hydrogen peroxide, significantly lower numbers of HP1 survived than was the case in the wild type. These results suggest that HupO is associated with virulence expression in V. fluvialis through stimulation of hemolysin production and resistance to oxidative stress. In experimentally infected mice, the 50% lethal dose value of the wild-type was lower than that of the mutant, HP1.

Identification of the outer-membrane protein PagC required for the serum resistance phenotype in Salmonella enterica serovar Choleraesuis

Microbiology ◽  
2005 ◽  
Vol 151 (3) ◽  
pp. 863-873 ◽  
Author(s):  
Miki Nishio ◽  
Nobuhiko Okada ◽  
Tsuyoshi Miki ◽  
Takeshi Haneda ◽  
Hirofumi Danbara
Keyword(s):  
Membrane Protein ◽  
Outer Membrane ◽  
Outer Membrane Protein ◽  
Salmonella Enterica ◽  
Pathogenic Bacteria ◽  
Insertional Mutagenesis ◽  
Genomic Library ◽  
Serum Resistance ◽  
Resistance Phenotype ◽  
Systemic Infections

Serum resistance is a crucial virulence factor for the development of systemic infections, including bacteraemia, by many pathogenic bacteria. Salmonella enterica serovar Choleraesuis is an important enteric pathogen that causes serious systemic infections in swine and humans. Here, it was found that, when introduced into Escherichia coli, a recombinant plasmid carrying the pagC gene from a plasmid-based genomic library of S. enterica serovar Choleraesuis conferred a high-level resistance to the bactericidal activity of pooled normal swine serum. The resistance was equal to the level conferred by rck, a gene encoding a 17 kDa outer-membrane protein which promotes the serum resistance phenotype in S. enterica serovar Typhimurium. Insertional mutagenesis of the cloned pagC gene generated a mutation that resulted in the loss of the serum resistance phenotype in E. coli. When this mutation was introduced into the chromosome of S. enterica serovar Choleraesuis by homology recombination with the wild-type allele, the resulting strain could not produce PagC, and it showed a decreased level of resistance to complement-mediated killing. The mutation could be restored by introduction of the intact pagC gene on a plasmid, but not by introduction of the point-mutated pagC gene. In addition, PagC was able to promote serum resistance in the S. enterica serovar Choleraesuis LPS mutant strain, which is highly sensitive to serum killing. Although PagC is not thought to confer serum resistance directly, these results strongly suggest that PagC is an important outer-membrane protein that plays an important role in the serum resistance of S. enterica serovar Choleraesuis.

scholarly journals Outer Membrane Protein STM3031 (Ail/OmpX-Like Protein) Plays a Key Role in the Ceftriaxone Resistance of Salmonella enterica Serovar Typhimurium

2009 ◽  
Vol 53 (8) ◽  
pp. 3248-3255 ◽  
Author(s):  
Wensi S. Hu ◽  
Jing-Fang Lin ◽  
Ying-Hsiu Lin ◽  
Hsin-Yu Chang
Keyword(s):  
Membrane Protein ◽  
Outer Membrane ◽  
Outer Membrane Protein ◽  
Salmonella Enterica ◽  
Efflux Pump ◽  
Protein S ◽  
Mrna Levels ◽  
Expression Levels ◽  
Protein Levels ◽  
Serovar Typhimurium

ABSTRACT Previously, the putative outer membrane protein STM3031 has been correlated with ceftriaxone resistance in Salmonella enterica serovar Typhimurium. In this study, this protein was almost undetectable in the ceftriaxone-susceptible strain 01-4, but its levels were increased in 01-4 isogenic strains for which MICs were higher. The stm3031 gene deletion mutant, R200(Δstm3031), was generated and showed >64-fold lower ceftriaxone resistance than R200, supporting a key role for STM3031 in ceftriaxone resistance. To investigate which outer membrane protein(s) was associated with resistance, the outer membrane protein profiles of 01-4, R200, and R200(Δstm3031) were compared proteomically. Nine proteins were identified as altered. The expression levels of AcrA, TolC, STM3031, STM1530, VacJ, and Psd in R200 were increased; those of OmpC, OmpD, and OmpW were decreased. The expression levels of OmpD, OmpW, STM1530, VacJ, and Psd, but not those of OmpC, AcrA, and TolC, in R200(Δstm3031) were returned to the levels in strain 01-4. Furthermore, the genes' mRNA levels correlated with their protein levels when the three strains were compared. The detection of higher AcrB levels, linked to higher acrB, acrD, and acrF mRNA levels, in strain R200 than in strains 01-4 and R200(Δstm3031) suggests that AcrB, AcrD, and AcrF participate in ceftriaxone resistance. Taken together with the location of STM3031 in the outer membrane, these results suggest that STM3031 plays a key role in ceftriaxone resistance, probably by reducing permeability via a decreased porin OmpD level and enhancing export via increased AcrD efflux pump activity.

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