scholarly journals Role of the Helicobacter pylori outer-membrane proteins AlpA and AlpB in colonization of the guinea pig stomach

2004 ◽  
Vol 53 (5) ◽  
pp. 375-379 ◽  
Author(s):  
Ramon de Jonge ◽  
Zarmina Durrani ◽  
Sjoerd G. Rijpkema ◽  
Ernst J. Kuipers ◽  
Arnoud H.M. van Vliet ◽  
...  
Keyword(s):  
Helicobacter Pylori ◽  
Membrane Proteins ◽  
Guinea Pig ◽  
Outer Membrane ◽  
Type Strain ◽  
Wild Type Strain ◽  
Outer Membrane Proteins ◽  
Wild Type ◽  
H Pylori

The human gastric pathogen Helicobacter pylori expresses several putative outer-membrane proteins (OMPs), but the role of individual OMPs in colonization of the stomach by H. pylori is still poorly understood. The role of four such OMPs (AlpA, AlpB, OipA and HopZ) in a guinea pig model of H. pylori infection has been investigated. Single alpA, alpB, hopZ and oipA isogenic mutants were constructed in the guinea pig-adapted, wild-type H. pylori strain GP15. Guinea pigs were inoculated intragastrically with the wild-type strain, single mutants or a mixture of the wild-type and a single mutant in a 1 : 1 ratio. Three weeks after infection, H. pylori could be isolated from stomach sections of all animals that were infected with the wild-type, the hopZ mutant or the oipA mutant, but from only five of nine (P = 0.18) and one of seven (P = 0.02) animals that were infected with the alpA or alpB mutants, respectively. The hopZ and oipA mutants colonized the majority of animals that were inoculated with the strain mixture, whereas alpA and alpB mutants could not be isolated from animals that were infected with the strain mixture (P < 0.01). Specific IgG antibody responses were observed in all animals that were infected with either the wild-type or a mutant, but IgG levels were lower in animals that were infected with either the alpA or the alpB mutants, compared to the wild-type strain (P < 0.05). In conclusion, absence of AlpA or AlpB is a serious disadvantage for colonization of the stomach by H. pylori.

scholarly journals Role of β-Lactamases and Porins in Resistance to Ertapenem and Other β-Lactams in Klebsiella pneumoniae

2004 ◽  
Vol 48 (8) ◽  
pp. 3203-3206 ◽  
Author(s):  
George A. Jacoby ◽  
Debra M. Mills ◽  
Nancy Chow
Keyword(s):  
Klebsiella Pneumoniae ◽  
Outer Membrane ◽  
Type Strain ◽  
Wild Type Strain ◽  
Outer Membrane Proteins ◽  
Wild Type ◽  
Resistant Mutants ◽  
High Level ◽  
Level Resistance

ABSTRACT High-level resistance to ertapenem was produced by β-lactamases of groups 1, 2f, and 3 in a strain of Klebsiella pneumoniae deficient in Omp35 and Omp36. From a wild-type strain producing ACT-1 β-lactamase, ertapenem-resistant mutants for which the ertapenem MICs were up to 128 μg/ml and expression of outer membrane proteins was diminished could be selected.

scholarly journals Novel Toluene Elimination System in a Toluene-Tolerant Microorganism

2000 ◽  
Vol 182 (22) ◽  
pp. 6451-6455 ◽  
Author(s):  
Hideki Kobayashi ◽  
Katsuyuki Uematsu ◽  
Hisako Hirayama ◽  
Koki Horikoshi
Keyword(s):  
Membrane Proteins ◽  
Cell Membrane ◽  
Outer Membrane ◽  
Parent Strain ◽  
Type Strain ◽  
Wild Type Strain ◽  
Outer Membrane Proteins ◽  
Membrane Vesicles ◽  
Wild Type ◽  
Sensitive Mutant

ABSTRACT In studies of Pseudomonas putida IH-2000, a toluene-tolerant microorganism, membrane vesicles (MVs) were found to be released from the outer membrane when toluene was added to the culture. These MVs were found to be composed of phospholipids, lipopolysaccharides (LPS), and very low amounts of outer membrane proteins. The MVs also contained a higher concentration of toluene molecules (0.172 ± 0.012 mol/mol of lipid) than that found in the cell membrane. In contrast to the wild-type strain, the toluene-sensitive mutant strain 32, which differs from the parent strain in LPS and outer membrane proteins, did not release MVs from the outer membrane. The toluene molecules adhering to the outer membrane are eliminated by the shedding of MVs, and this system appears to serve as an important part of the toluene tolerance system of IH-2000.

scholarly journals Detailed In Vivo Analysis of the Role of Helicobacter pylori Fur in Colonization and Disease

2010 ◽  
Vol 78 (7) ◽  
pp. 3073-3082 ◽  
Author(s):  
Shana Miles ◽  
M. Blanca Piazuelo ◽  
Cristina Semino-Mora ◽  
Mary Kay Washington ◽  
Andre Dubois ◽  
...  
Keyword(s):  
Helicobacter Pylori ◽  
Mongolian Gerbil ◽  
Type Strain ◽  
Wild Type Strain ◽  
Temporal Analysis ◽  
Wild Type ◽  
Invasive Adenocarcinoma ◽  
H Pylori

ABSTRACT Helicobacter pylori persistently colonizes the harsh and dynamic environment of the stomach in over one-half of the world's population and has been identified as a causal agent in a spectrum of pathologies that range from gastritis to invasive adenocarcinoma. The ferric uptake regulator (Fur) is one of the few regulatory proteins that has been identified in H. pylori. Fur regulates genes important for acid acclimation and oxidative stress and has been shown to be important for colonization of H. pylori in both murine and Mongolian gerbil models of infection. To more thoroughly define the role of Fur in vivo, we conducted an extensive temporal analysis of the location of, competitive ability of, and resultant pathology induced by a Δfur strain in the Mongolian gerbil model of infection and compared the results to results for its wild-type parent. We found that at the earliest time points postinfection, significantly more Δfur bacteria than wild-type bacteria were recovered. However, this trend was reversed by day 3, when there was significantly increased recovery of the wild-type strain. The increased recovery of the Δfur strain at 1 day postinfection reflected increased recovery from both the corpus and the antrum of the stomach. When the wild-type strain was allowed to colonize first, the Δfur strain was unable to compete for colonization at any time postinfection. However, when the Δfur strain was allowed to colonize first, the wild type efficiently outcompeted the Δfur strain only at early times postinfection. Finally, we demonstrated that there was a delay in the development and severity of inflammation and pathology of the Δfur strain in the gastric mucosa even after comparable levels of colonization occurred. Together, these data indicate that H. pylori Fur is most important at early stages of infection and illustrate the importance of the ability of H. pylori to adapt to its constantly fluctuating environment when it is establishing infection, inflammation, and disease.

scholarly journals The toxR Gene of Vibrio(Listonella) anguillarum Controls Expression of the Major Outer Membrane Proteins but Not Virulence in a Natural Host Model

2001 ◽  
Vol 69 (10) ◽  
pp. 6091-6101 ◽  
Author(s):  
Jun Okuda ◽  
Toshihiro Nakai ◽  
Park Se Chang ◽  
Takanori Oh ◽  
Takeshi Nishino ◽  
...  
Keyword(s):  
Outer Membrane ◽  
Type Strain ◽  
Wild Type Strain ◽  
Outer Membrane Proteins ◽  
Sodium Dodecyl ◽  
Amino Acid Sequences ◽  
Wild Type ◽  
Plecoglossus Altivelis ◽  
The Family

ABSTRACT To examine the hypothesis that the ancestral role of thetoxR gene in the family Vibrionaceae is control of the expression of outer membrane protein (OMP)-encoding genes for adaptation to environmental change, we investigated the role of thetoxR gene in Vibrio anguillarum, an important fish pathogen. The toxR gene of V. angullarum (Va-toxR) was cloned from strain PT-87050 isolated from diseased ayu (Plecoglossus altivelis), and the sequence was analyzed. The toxR sequence was 63 to 51% identical to those reported for other species of the familyVibrionaceae. Distribution of the Va-toxR gene sequence in V. anguillarum strains of various serotypes was confirmed by using DNA probe and PCR methods. An isogenictoxR mutant of V. anguillarum PT-24, isolated from diseased ayu, was constructed by using an allelic exchange method. The wild-type strain and the toxR mutant did not differ in the ability to produce a protease(s) and a hemolysin(s) or in pathogenicity for ayu when examined by the intramuscular injection and immersion methods. A 35-kDa major OMP was not produced by the toxR mutant. However, a 46-kDa OMP was hardly detected in the wild-type strain but was produced as the major OMP by the toxR mutant. For the toxR mutant, the MICs of two β-lactam antibiotics were higher and the minimum bactericidal concentration of sodium dodecyl sulfate was lower than for the wild-type strain. Analysis of the N-terminal amino acid sequences of the 35- and 46-kDa OMPs indicated that these proteins are the porin-like OMPs and are related to the toxR-regulated major OMPs of the family Vibrionaceae. The results indicate that the toxR gene is not involved in virulence expression inV. anguillarum PT-24 and that toxRregulation of major OMPs is universal in the familyVibrionaceae. These results support the hypothesis that the ancestral role of the toxR gene is regulation of OMP gene expression and that only in some Vibrio species has ToxR been appropriated for the regulation of a virulence gene(s).

scholarly journals Functions of the BamBCDE Lipoproteins Revealed by Bypass Mutations in BamA

2020 ◽  
Vol 202 (21) ◽  
Author(s):  
Elizabeth M. Hart ◽  
Thomas J. Silhavy
Keyword(s):  
Membrane Proteins ◽  
Outer Membrane ◽  
Outer Membrane Proteins ◽  
Gram Negative Bacteria ◽  
Wild Type ◽  
Gram Negative ◽  
Bam Complex ◽  
Essential Function ◽  
The Individual

ABSTRACT The heteropentomeric β-barrel assembly machine (BAM complex) is responsible for folding and inserting a diverse array of β-barrel outer membrane proteins (OMPs) into the outer membrane (OM) of Gram-negative bacteria. The BAM complex contains two essential proteins, the β-barrel OMP BamA and a lipoprotein BamD, whereas the auxiliary lipoproteins BamBCE are individually nonessential. Here, we identify and characterize three bamA mutations, the E-to-K change at position 470 (bamAE470K), the A-to-P change at position 496 (bamAA496P), and the A-to-S change at position 499 (bamAA499S), that suppress the otherwise lethal ΔbamD, ΔbamB ΔbamC ΔbamE, and ΔbamC ΔbamD ΔbamE mutations. The viability of cells lacking different combinations of BAM complex lipoproteins provides the opportunity to examine the role of the individual proteins in OMP assembly. Results show that, in wild-type cells, BamBCE share a redundant function; at least one of these lipoproteins must be present to allow BamD to coordinate productively with BamA. Besides BamA regulation, BamD shares an additional essential function that is redundant with a second function of BamB. Remarkably, bamAE470K suppresses both, allowing the construction of a BAM complex composed solely of BamAE470K that is able to assemble OMPs in the absence of BamBCDE. This work demonstrates that the BAM complex lipoproteins do not participate in the catalytic folding of OMP substrates but rather function to increase the efficiency of the assembly process by coordinating and regulating the assembly of diverse OMP substrates. IMPORTANCE The folding and insertion of β-barrel outer membrane proteins (OMPs) are conserved processes in mitochondria, chloroplasts, and Gram-negative bacteria. In Gram-negative bacteria, OMPs are assembled into the outer membrane (OM) by the heteropentomeric β-barrel assembly machine (BAM complex). In this study, we probe the function of the individual BAM proteins and how they coordinate assembly of a diverse family of OMPs. Furthermore, we identify a gain-of-function bamA mutant capable of assembling OMPs independently of all four other BAM proteins. This work advances our understanding of OMP assembly and sheds light on how this process is distinct in Gram-negative bacteria.

scholarly journals Involvement of CO2 generated by urease in multiplication of Helicobacter pylori

2021 ◽  
Vol 7 (3) ◽  
pp. 045-053
Author(s):  
Masaaki Minami ◽  
Shin-nosuke Hashikawa ◽  
Takafumi Ando ◽  
Hiroshi Kobayashi ◽  
Hidemi Goto ◽  
...  
Keyword(s):  
Helicobacter Pylori ◽  
Mutant Strain ◽  
Type Strain ◽  
Wild Type Strain ◽  
Neutral Medium ◽  
Wild Type ◽  
In The Wild ◽  
H Pylori ◽  
Carbon Dioxide Co2 ◽  
The Relationship

Helicobacter pylori (H. pylori) urease generates both ammonia (NH3) and carbon dioxide (CO2) from urea. NH3 helps H. pylori to survive in the stomach in part by neutralizing gastric acid. However, the relationship between CO2 and H. pylori is not completed cleared. We examined the effect of CO2 generated by urease on multiplication of H. pylori by using isogenic ureB mutant and ureB complemented strain from H. pylori strain JP26. Wild-type strain survived in the medium supplement with 1mM urea in room air, however, the urease negative strain did not. To discern whether CO2 was incorporated into H. pylori, 14C in bacillus was counted after 6 hours incubation with 14C urea in both acidic and neutral medium. Significant more 14C uptake was detected in wild-type strain compared to ureB mutant strain and this uptake in the wild-type strain was more under acidic condition compared to under neutral condition, but no difference was identified in the mutant strain. These results suggest that CO2 generated by urease plays a role in multiplication of H. pylori.

scholarly journals The Role of a Dipeptide Transporter in the Virulence of Human Pathogen, Helicobacter pylori

2021 ◽  
Vol 12 ◽  
Author(s):  
Xiaohong Xu ◽  
Junwei Chen ◽  
Xiaoxing Huang ◽  
Shunhang Feng ◽  
Xiaoyan Zhang ◽  
...  
Keyword(s):  
Helicobacter Pylori ◽  
Virulence Factors ◽  
Outer Membrane Proteins ◽  
Wild Type ◽  
Ags Cells ◽  
Dipeptide Transporter ◽  
Adhesion Level ◽  
H Pylori ◽  
Substrate Binding Protein

Helicobacter pylori harbors a dipeptide (Dpp) transporter consisting of a substrate-binding protein (DppA), two permeases (DppB and C), and two ATPases (DppD and F). The Dpp transporter is responsible for the transportation of dipeptides and short peptides. We found that its expression is important for the growth of H. pylori. To understand the role of the Dpp transporter in the pathogenesis of H. pylori, the expression of virulence factors and H. pylori-induced IL-8 production were investigated in H. pylori wild-type and isogenic H. pylori Dpp transporter mutants. We found that expression of CagA was downregulated, while expression of type 4 secretion system (T4SS) components was upregulated in Dpp transporter mutants. The DppA mutant strain expressed higher levels of outer membrane proteins (OMPs), including BabA, HopZ, OipA, and SabA, and showed a higher adhesion level to gastric epithelial AGS cells compared with the H. pylori 26695 wild-type strain. After infection of AGS cells, H. pylori ΔdppA induced a higher level of NF-κB activation and IL-8 production compared with wild-type. These results suggested that in addition to supporting the growth of H. pylori, the Dpp transporter causes bacteria to alter the expression of virulence factors and reduces H. pylori-induced NF-κB activation and IL-8 production in gastric epithelial cells.

scholarly journals Helicobacter pyloriOuter Membrane Protein 18 (Hp1125) Is Involved in Persistent Colonization by Evading Interferon-γSignaling

2015 ◽  
Vol 2015 ◽  
pp. 1-12 ◽  
Author(s):  
Yuqun Shan ◽  
Xingxiao Lu ◽  
Yingnan Han ◽  
Xinpeng Li ◽  
Xiao Wang ◽  
...  
Keyword(s):  
Immune Response ◽  
Type Strain ◽  
Wild Type Strain ◽  
Outer Membrane Proteins ◽  
Immune Surveillance ◽  
Survival Rates ◽  
Wild Type ◽  
Qrt Pcr ◽  
H Pylori ◽  
Host Immune Surveillance

Outer membrane proteins (OMPs) can induce an immune response. Omp18 (HP1125) ofH. pyloriis a powerful antigen that can induce significant interferon-γ(IFN-γ) levels. Previous studies have suggested that IFN-γplays an important role inH. pyloriclearance. However,H. pylorihas multiple mechanisms to avoid host immune surveillance for persistent colonization. We generated anomp18mutant (H. pylori26695 andH. pyloriSS1) strain to examine whether Omp18 interacts with IFN-γand is involved inH. pyloricolonization. qRT-PCR revealed that IFN-γinduced Omp18 expression. qRT-PCR and western blot analysis revealed reduced expressions of virulence factors CagA and NapA inH. pylori26695 with IFN-γtreatment, but they were induced in the Δomp18strain. In C57BL/6 mice infected withH. pyloriSS1 and the Δomp18strain, the Δomp18strain conferred defective colonization and activated a stronger inflammatory response. Signal transducer phosphorylation and transcription 1 (STAT1) activator was downregulated by the wild-type strain but not the Δomp18strain in IFN-γ-treated macrophages. Furthermore, Δomp18strain survival rates were poor in macrophages compared to the wild-type strain. We concluded thatH. pyloriOmp18 has an important function influencing IFN-γ-mediated immune response to participate in persistent colonization.

scholarly journals Role of vimA in cell surface biogenesis in Porphyromonas gingivalis

Microbiology ◽  
2010 ◽  
Vol 156 (7) ◽  
pp. 2180-2193 ◽  
Author(s):  
Devon O. Osbourne ◽  
Wilson Aruni ◽  
Francis Roy ◽  
Christopher Perry ◽  
Lawrence Sandberg ◽  
...  
Keyword(s):  
Cell Surface ◽  
Outer Membrane ◽  
Porphyromonas Gingivalis ◽  
Type Strain ◽  
Wild Type Strain ◽  
Phenotypic Expression ◽  
Surface Proteins ◽  
Wild Type ◽  
In The Wild

The Porphyromonas gingivalis vimA gene has been previously shown to play a significant role in the biogenesis of gingipains. Further, in P. gingivalis FLL92, a vimA-defective mutant, there was increased auto-aggregation, suggesting alteration in membrane surface proteins. In order to determine the role of the VimA protein in cell surface biogenesis, the surface morphology of P. gingivalis FLL92 was further characterized. Transmission electron microscopy demonstrated abundant fimbrial appendages and a less well defined and irregular capsule in FLL92 compared with the wild-type. In addition, atomic force microscopy showed that the wild-type had a smoother surface compared with FLL92. Western blot analysis using anti-FimA antibodies showed a 41 kDa immunoreactive protein band in P. gingivalis FLL92 which was missing in the wild-type P. gingivalis W83 strain. There was increased sensitivity to globomycin and vancomycin in FLL92 compared with the wild-type. Outer membrane fractions from FLL92 had a modified lectin-binding profile. Furthermore, in contrast with the wild-type strain, nine proteins were missing from the outer membrane fraction of FLL92, while 20 proteins present in that fraction from FLL92 were missing in the wild-type strain. Taken together, these results suggest that the VimA protein affects capsular synthesis and fimbrial phenotypic expression, and plays a role in the glycosylation and anchorage of several surface proteins.

Helicobacter pylori infection in mice: Role of outer membrane proteins in colonization and inflammation

2002 ◽  
Vol 123 (6) ◽  
pp. 1992-2004 ◽  
Author(s):  
Yoshio Yamaoka ◽  
Masakazu Kita ◽  
Tadashi Kodama ◽  
Shigeyoshi Imamura ◽  
Tomoyuki Ohno ◽  
...  
Keyword(s):  
Helicobacter Pylori ◽  
Membrane Proteins ◽  
Outer Membrane ◽  
Outer Membrane Proteins ◽  
Helicobacter Pylori Infection
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