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 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 The role of Zur-regulated lipoprotein A in bacterial morphology, antimicrobial susceptibility, and production of outer membrane vesicles in Acinetobacter baumannii

2021 ◽  
Vol 21 (1) ◽  
Author(s):  
Nayeong Kim ◽  
Hyo Jeong Kim ◽  
Man Hwan Oh ◽  
Se Yeon Kim ◽  
Mi Hyun Kim ◽  
...  
Keyword(s):  
Acinetobacter Baumannii ◽  
Outer Membrane ◽  
Mutant Strain ◽  
Antimicrobial Susceptibility ◽  
Type Strain ◽  
Wild Type Strain ◽  
Membrane Vesicles ◽  
Outer Membrane Vesicles ◽  
Wild Type ◽  
Bacterial Morphology

Abstract Background Zinc uptake-regulator (Zur)-regulated lipoprotein A (ZrlA) plays a role in bacterial fitness and overcoming antimicrobial exposure in Acinetobacter baumannii. This study further characterized the zrlA gene and its encoded protein and investigated the roles of the zrlA gene in bacterial morphology, antimicrobial susceptibility, and production of outer membrane vesicles (OMVs) in A. baumannii ATCC 17978. Results In silico and polymerase chain reaction analyses showed that the zrlA gene was conserved among A. baumannii strains with 97–100% sequence homology. Recombinant ZrlA protein exhibited a specific enzymatic activity of D-alanine-D-alanine carboxypeptidase. Wild-type A. baumannii exhibited more morphological heterogeneity than a ΔzrlA mutant strain during stationary phase. The ΔzrlA mutant strain was more susceptible to gentamicin than the wild-type strain. Sizes and protein profiles of OMVs were similar between the wild-type and ΔzrlA mutant strains, but the ΔzrlA mutant strain produced 9.7 times more OMV particles than the wild-type strain. OMVs from the ΔzrlA mutant were more cytotoxic in cultured epithelial cells than OMVs from the wild-type strain. Conclusions The present study demonstrated that A. baumannii ZrlA contributes to bacterial morphogenesis and antimicrobial resistance, but its deletion increases OMV production and OMV-mediated host cell cytotoxicity.

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 Unravelling potential virulence factor candidates inXanthomonas citri. subsp.citriby secretome analysis

PeerJ ◽  
2016 ◽  
Vol 4 ◽  
pp. e1734 ◽  
Author(s):  
Rafael M. Ferreira ◽  
Leandro M. Moreira ◽  
Jesus A. Ferro ◽  
Marcia R.R. Soares ◽  
Marcelo L. Laia ◽  
...  
Keyword(s):  
Membrane Protein ◽  
Outer Membrane ◽  
Type Strain ◽  
Wild Type Strain ◽  
Outer Membrane Proteins ◽  
Citrus Canker ◽  
Trna Synthetase ◽  
Hypothetical Proteins ◽  
Wild Type ◽  
In The Wild

Citrus canker is a major disease affecting citrus production in Brazil. It’s mainly caused byXanthomonas citrisubsp.citristrain 306 pathotype A (Xac). We analysed the differential expression of proteins secreted by wild typeXacand an asymptomatic mutant forhrpB4(ΔhrpB4) grown in Nutrient Broth (NB) and a medium mimicking growth conditions in the plant (XAM1). This allowed the identification of 55 secreted proteins, of which 37 were secreted by both strains when cultured in XAM1. In this secreted protein repertoire, the following stand out: Virk, Polyphosphate-selective porin, Cellulase, Endoglucanase, Histone-like protein, Ribosomal proteins, five hypothetical proteins expressed only in the wild type strain, Lytic murein transglycosylase, Lipoprotein, Leucyl-tRNA synthetase, Co-chaperonin, Toluene tolerance, C-type cytochrome biogenesis membrane protein, Aminopeptidase and two hypothetical proteins expressed only in the ΔhrpB4mutant. Furthermore, Peptidoglycan-associated outer membrane protein, Regulator of pathogenicity factor, Outer membrane proteins, Endopolygalacturonase, Chorismate mutase, Peptidyl-prolyl cis-trans isomerase and seven hypothetical proteins were detected in both strains, suggesting that there was no relationship with the secretion mediated by the type III secretory system, which is not functional in the mutant strain. Also worth mentioning is the Elongation factor Tu (EF-Tu), expressed only the wild type strain, and Type IV pilus assembly protein, Flagellin (FliC) and Flagellar hook-associated protein, identified in the wild-type strain secretome when grown only in NB. Noteworthy, that FliC, EF-Tu are classically characterized as PAMPs (Pathogen-associated molecular patterns), responsible for a PAMP-triggered immunity response. Therefore, our results highlight proteins potentially involved with the virulence. Overall, we conclude that the use of secretome data is a valuable approach that may bring more knowledge of the biology of this important plant pathogen, which ultimately can lead to the establishment of new strategies to combat citrus canker.

scholarly journals The sensor kinase BfmS controls production of outer membrane vesicles in Acinetobacter baumannii

2019 ◽  
Vol 19 (1) ◽  
Author(s):  
Se Yeon Kim ◽  
Mi Hyun Kim ◽  
Seung Il Kim ◽  
Joo Hee Son ◽  
Shukho Kim ◽  
...  
Keyword(s):  
Antimicrobial Resistance ◽  
Acinetobacter Baumannii ◽  
Outer Membrane ◽  
Type Strain ◽  
Wild Type Strain ◽  
A549 Cells ◽  
Membrane Vesicles ◽  
Outer Membrane Vesicles ◽  
Sensor Kinase ◽  
Wild Type

Abstract Background Acinetobacter baumannii is an important opportunistic pathogen responsible for various nosocomial infections. The BfmRS two-component system plays a role in pathogenesis and antimicrobial resistance of A. baumannii via regulation of bacterial envelope structures. This study investigated the role of the sensor kinase, BfmS, in localization of outer membrane protein A (OmpA) in the outer membrane and production of outer membrane vesicles (OMVs) using wild-type A. baumannii ATCC 17978, ΔbfmS mutant, and bfmS-complemented strains. Results The ΔbfmS mutant showed hypermucoid phenotype in the culture plates, growth retardation under static culture conditions, and reduced susceptibility to aztreonam and colistin compared to the wild-type strain. The ΔbfmS mutant produced less OmpA in the outer membrane but released more OmpA via OMVs than the wild-type strain, even though expression of ompA and its protein production were not different between the two strains. The ΔbfmS mutant produced 2.35 times more OMV particles and 4.46 times more OMV proteins than the wild-type stain. The ΔbfmS mutant OMVs were more cytotoxic towards A549 cells than wild-type strain OMVs. Conclusions The present study demonstrates that BfmS controls production of OMVs in A. baumannii. Moreover, BfmS negatively regulates antimicrobial resistance of A. baumannii and OMV-mediated host cell cytotoxicity. Our results indicate that BfmS negatively controls the pathogenic traits of A. baumannii via cell envelope structures and OMV production.

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).

Extrusion of actin-positive strands from HEp-2 and Int 407 cells caused by outer membrane preparations of enteropathogenicEscherichia coliand specific attachment of wild type bacteria to the strands

2001 ◽  
Vol 47 (8) ◽  
pp. 727-734 ◽  
Author(s):  
Sukumaran Sunil Kumar ◽  
Vasantha Malladi ◽  
Krishnan Sankaran ◽  
Richard Haigh ◽  
Peter Williams ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Membrane Proteins ◽  
Outer Membrane ◽  
Outer Membrane Proteins ◽  
Three Dimensional ◽  
Secretory Proteins ◽  
Enteropathogenic Escherichia Coli ◽  
Wild Type ◽  
Cytopathic Effects ◽  
Cytoskeletal Elements

Enteropathogenic Escherichia coli (EPEC) causes persistent infantile diarrhoea. This nontoxigenic E. coli exhibits a complicated pathogenic mechanism in which its outer membrane proteins and type III secretory proteins damage intestinal epithelium and cause diarrhoea. In accordance with this, our previous study using HEp-2 cells demonstrated cytopathic effects caused by cell-free outer membrane preparations of EPEC. In this study, we report the extrusion of actin-positive strands from HEp-2 and Int 407 cells when treated with outer membrane preparations. An interesting observation of this work, perhaps relevant to the characteristic localized three-dimensional colony formation of EPEC, is the attachment of a wild type EPEC strain to these actin-positive strands.Key words: enteropathogenic Escherichia coli, actin, outer membrane proteins, cytoskeletal elements.

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.

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