scholarly journals Innate secretory antibodies protect against natural Salmonella typhimurium infection

2006 ◽  
Vol 203 (1) ◽  
pp. 21-26 ◽  
Author(s):  
Odilia L.C. Wijburg ◽  
Tania K. Uren ◽  
Kim Simpfendorfer ◽  
Finn-Eirik Johansen ◽  
Per Brandtzaeg ◽  
...  
Keyword(s):  
Salmonella Typhimurium ◽  
Natural Infection ◽  
Oral Route ◽  
Microbial Pathogens ◽  
Infection Model ◽  
Knock Out ◽  
Immunoglobulin Receptor ◽  
Secretory Antibodies

The production of IgA is induced in an antigen-unspecific manner by commensal flora. These secretory antibodies (SAbs) may bind multiple antigens and are thought to eliminate commensal bacteria and self-antigens to avoid systemic recognition. In this study, we addressed the role of “innate” SAbs, i.e., those that are continuously produced in normal individuals, in protection against infection of the gastrointestinal tract. We used polymeric immunoglobulin receptor (pIgR−/−) knock-out mice, which are unable to bind and actively transport dimeric IgA and pentameric IgM to the mucosae, and examined the role of innate SAbs in protection against the invasive pathogen Salmonella typhimurium. In vitro experiments suggested that innate IgA in pIgR−/− serum bound S. typhimurium in a cross-reactive manner which inhibited epithelial cell invasion. Using a “natural” infection model, we demonstrated that pIgR−/− mice are profoundly sensitive to infection with S. typhimurium via the fecal-oral route and, moreover, shed more bacteria that readily infected other animals. These results imply an important evolutionary role for innate SAbs in protecting both the individual and the herd against infections, and suggest that the major role of SAbs may be to prevent the spread of microbial pathogens throughout the population, rather than protection of local mucosal surfaces.

scholarly journals The Extracellular Small Leucine-Rich Proteoglycan Biglycan Is a Key Player in Gastric Cancer Aggressiveness

Cancers ◽  
2021 ◽  
Vol 13 (6) ◽  
pp. 1330
Author(s):  
Filipe Pinto ◽  
Liliana Santos-Ferreira ◽  
Marta T. Pinto ◽  
Catarina Gomes ◽  
Celso A. Reis
Keyword(s):  
Clinical Value ◽  
Knock Out ◽  
Angiogenic Potential ◽  
In Vivo Experiments ◽  
Cancer Aggressiveness ◽  
Advanced Stages ◽  
Oncogenic Gene

Biglycan (BGN gene), an extracellular proteoglycan, has been described to be associated with cancer aggressiveness. The purpose of this study was to clarify the clinical value of biglycan as a biomarker in multiple independent GC cohorts and determine the in vitro and in vivo role of biglycan in GC malignant features. We found that BGN is commonly over-expressed in all analyzed cohorts, being associated with disease relapse and poor prognosis in patients with advanced stages of disease. In vitro and in vivo experiments demonstrated that biglycan knock-out GC cells display major phenotypic changes with a lower cell survival, migration, and angiogenic potential when compared with biglycan expressing cells. Biglycan KO GC cells present increased levels of PARP1 and caspase-3 cleavage and a decreased expression of mesenchymal markers. Importantly, biglycan deficient GC cells that were supplemented with exogenous biglycan were able to restore biological features, such as survival, clonogenic and migratory capacities. Our in vitro and in vivo findings were validated in human GC samples, where BGN expression was associated with several oncogenic gene signatures that were associated with apoptosis, cell migration, invasion, and angiogenesis. This study provided new insights on biglycan role in GC that should be taken in consideration as a key cellular regulator with major impact in tumor progression and patients’ clinical outcome.

scholarly journals Activity of the Pore-Forming Virulence Factor Listeriolysin O Is Reversibly Inhibited by Naturally Occurring S-Glutathionylation

2017 ◽  
Vol 85 (4) ◽  
Author(s):  
Jonathan L. Portman ◽  
Qiongying Huang ◽  
Michelle L. Reniere ◽  
Anthony T. Iavarone ◽  
Daniel A. Portnoy
Keyword(s):  
Protein Function ◽  
Inhibitory Effect ◽  
Cysteine Residue ◽  
Infection Model ◽  
Listeriolysin O ◽  
Content Type ◽  
Pore Forming Proteins

ABSTRACT Cholesterol-dependent cytolysins (CDCs) represent a family of homologous pore-forming proteins secreted by many Gram-positive bacterial pathogens. CDCs mediate membrane binding partly through a conserved C-terminal undecapeptide, which contains a single cysteine residue. While mutational changes to other residues in the undecapeptide typically have severe effects, mutation of the cysteine residue to alanine has minor effects on overall protein function. Thus, the role of this highly conserved reactive cysteine residue remains largely unknown. We report here that the CDC listeriolysin O (LLO), secreted by the facultative intracellular pathogen Listeria monocytogenes, was posttranslationally modified by S-glutathionylation at this conserved cysteine residue and that either endogenously synthesized or exogenously added glutathione was sufficient to form this modification. When recapitulated with purified protein in vitro, this modification completely ablated the activity of LLO, and this inhibitory effect was fully reversible by treatment with reducing agents. A cysteine-to-alanine mutation in LLO rendered the protein completely resistant to inactivation by S-glutathionylation, and a mutant expressing this mutation retained full hemolytic activity. A mutant strain of L. monocytogenes expressing the cysteine-to-alanine variant of LLO was able to infect and replicate within bone marrow-derived macrophages indistinguishably from the wild type in vitro, yet it was attenuated 4- to 6-fold in a competitive murine infection model in vivo. This study suggests that S-glutathionylation may represent a mechanism by which CDC-family proteins are posttranslationally modified and regulated and help explain an evolutionary pressure to retain the highly conserved undecapeptide cysteine.

scholarly journals Characterization of the Urease Operon of Brucella abortus and Assessment of Its Role in Virulence of the Bacterium

2006 ◽  
Vol 75 (2) ◽  
pp. 774-780 ◽  
Author(s):  
Félix J. Sangari ◽  
Asunción Seoane ◽  
María Cruz Rodríguez ◽  
Jesús Agüero ◽  
Juan M. García Lobo
Keyword(s):  
Brucella Abortus ◽  
Urease Activity ◽  
Strong Acid ◽  
Oral Route ◽  
Open Reading Frames ◽  
Human Brucellosis ◽  
Major Route

ABSTRACT Most members of the genus Brucella show strong urease activity. However, the role of this enzyme in the pathogenesis of Brucella infections is poorly understood. We isolated several Tn5 insertion mutants deficient in urease activity from Brucella abortus strain 2308. The mutations of most of these mutants mapped to a 5.7-kbp DNA region essential for urease activity. Sequencing of this region, designated ure1, revealed the presence of seven open reading frames corresponding to the urease structural proteins (UreA, UreB, and UreC) and the accessory proteins (UreD, UreE, UreF, and UreG). In addition to the urease genes, another gene (cobT) was identified, and inactivation of this gene affected urease activity in Brucella. Subsequent analysis of the previously described sequences of the genomes of Brucella spp. revealed the presence of a second urease cluster, ure2, in all them. The ure2 locus was apparently inactive in B. abortus 2308. Urease-deficient mutants were used to evaluate the role of urease in Brucella pathogenesis. The urease-producing strains were found to be resistant in vitro to strong acid conditions in the presence of urea, while urease-negative mutants were susceptible to acid treatment. Similarly, the urease-negative mutants were killed more efficiently than the urease-producing strains during transit through the stomach. These results suggested that urease protects brucellae during their passage through the stomach when the bacteria are acquired by the oral route, which is the major route of infection in human brucellosis.

scholarly journals A novel function of M. tuberculosis chaperonin paralog GroEL1 in copper homeostasis

2019 ◽  
Author(s):  
Mohammed Yousuf Ansari ◽  
Sakshi D. Batra ◽  
Hina Ojha ◽  
Ashish ◽  
Jaya S. Tyagi ◽  
...  
Keyword(s):  
Dna Damage ◽  
Functional Divergence ◽  
Cellular Protein ◽  
Copper Stress ◽  
Titration Calorimetry ◽  
Evolutionary Divergence ◽  
Wild Type ◽  
Knock Out

AbstractMycobacterial GroELs namely GroEL1 and GroEL2 belong to the family of molecular chaperones, chaperonins. Chaperonins in Escherichia coli are termed as GroEL and GroES which are encoded by essential genes and are involved in cellular protein folding. GroEL1 has a characteristic Histidine-rich C-terminus contrary to its essential paralog GroEL2 and E. coli GroEL which have hydrophobic (GGM) repeats. Since Histidine richness is likely to be involved in metal binding, in this study we have attempted to decipher the role of GroEL1 protein in chelating metals and the consequent role on M. tuberculosis physiology. Using isothermal titration calorimetry (ITC), we found that GroEL1 binds copper, nickel and cobalt, with the highest binding affinity to copper. Since copper is known to be toxic at higher concentration, we cultured Wild Type M. tuberculosis H37Rv, groEL1 knock-out and groEL1-complemented strain with increasing concentrations of copper. We found that M. tuberculosis groEL1 knock out strain is more sensitive to copper than the wild type. Further hypothesizing that the probable mode of action of copper is by induction of oxidative stress, we attempted to understand the role of GroEL1 in redox silencing and hydroxyl radical mediated DNA damage. We interestingly found through our in vitro studies that GroEL1 is helpful in protection from copper stress through maintaining redox balance and free radical mediated DNA damage. Thus, these results indicate that the duplication of chaperonin genes in M. tuberculosis might have led to their evolutionary divergence and resulted in a functional divergence of chaperonins.

scholarly journals N-glycosylation of infectious bronchitis virus M41 spike determines receptor specificity

2020 ◽  
Vol 101 (6) ◽  
pp. 599-608
Author(s):  
K. M. Bouwman ◽  
N. Habraeken ◽  
A. Laconi ◽  
A. J. Berends ◽  
L. Groenewoud ◽  
...  
Keyword(s):  
Infectious Bronchitis Virus ◽  
Reverse Genetics ◽  
Glycosylation Site ◽  
Host Cells ◽  
Receptor Specificity ◽  
Knock Out ◽  
Recombinant Viruses ◽  
Infectious Bronchitis

Infection of chicken coronavirus infectious bronchitis virus (IBV) is initiated by binding of the viral heavily N-glycosylated attachment protein spike to the alpha-2,3-linked sialic acid receptor Neu5Ac. Previously, we have shown that N-glycosylation of recombinantly expressed receptor binding domain (RBD) of the spike of IBV-M41 is of critical importance for binding to chicken trachea tissue. Here we investigated the role of N-glycosylation of the RBD on receptor specificity and virus replication in the context of the virus particle. Using our reverse genetics system we were able to generate recombinant IBVs for nine-out-of-ten individual N-glycosylation mutants. In vitro growth kinetics of these viruses were comparable to the virus containing the wild-type M41-S1. Furthermore, Neu5Ac binding by the recombinant viruses containing single N-glycosylation site knock-out mutations matched the Neu5Ac binding observed with the recombinant RBDs. Five N-glycosylation mutants lost the ability to bind Neu5Ac and gained binding to a different, yet unknown, sialylated glycan receptor on host cells. These results demonstrate that N-glycosylation of IBV is a determinant for receptor specificity.

scholarly journals Inhibition of the Classical Pathway of Complement Activation Impairs Bacterial Clearance during Enterococcus faecalis Infection

2021 ◽  
Vol 89 (5) ◽  
Author(s):  
Eman M. Rabie Shehab El-Din ◽  
Abdelaziz Elgaml ◽  
Youssif M. Ali ◽  
Ramadan Hassan
Keyword(s):  
Enterococcus Faecalis ◽  
Microbial Pathogens ◽  
Health Concern ◽  
Classical Pathway ◽  
Bacterial Clearance ◽  
Limited Information ◽  
Content Type ◽  
Fab Fragments

ABSTRACT Enterococcus faecalis infections are considered a major public health concern worldwide. The complement system has a crucial role in the protection against different microbial pathogens, including E. faecalis. Complement can be activated through three different pathways, including the classical, lectin, and alternative pathways. There is limited information on the role of the classical pathway (CP) in protection against infections caused by E. faecalis. In the present study, we generated Fab fragments that successfully block the CP in mouse via inhibition of a key enzyme, C1s-A. Our results showed that anti-C1s-A Fab fragments block CP-mediated C3b and C4b deposition in vitro. We further showed that administration of anti-C1s-A Fab fragments significantly impairs the CP functional activity in vivo. Moreover, treatment of mice infected with E. faecalis using anti-C1s-A Fab fragments significantly impairs bacterial clearance as determined from the viable bacterial counts recovered from blood, kidneys, spleens, livers, and lungs of infected mice. Overall, this study highlights the essential role of the CP in host defense against E. faecalis.

Challenges with Wound Infection Models in Drug Development

2020 ◽  
Vol 21 (13) ◽  
pp. 1301-1312 ◽  
Author(s):  
Sandeep K. Shukla ◽  
Ajay K. Sharma ◽  
Vanya Gupta ◽  
Aman Kalonia ◽  
Priyanka Shaw
Keyword(s):  
Wound Healing ◽  
Wound Infection ◽  
Chronic Wound ◽  
Wound Care ◽  
Infection Model ◽  
In Vivo Models ◽  
Infection Models

: Wound research is an evolving science trying to unfold the complex untold mechanisms behind the wound healing cascade. In particular, interest is growing regarding the role of microorganisms in both acute and chronic wound healing. Microbial burden plays an important role in the persistence of chronic wounds, ultimately resulting in delayed wound healing. It is therefore important for clinicians to understand the evolution of infection science and its various etiologies. Therefore, to understand the role of bacterial biofilm in chronic wound pathogenesis, various in vitro and in vivo models are required to investigate biofilms in wound-like settings. Infection models should be refined comprising an important signet of biofilms. These models are eminent for translational research to obtain data for designing an improved wound care formulation. However, all the existing models possess limitations and do not fit properly in the model frame for developing wound care agents. Among various impediments, one of the major drawbacks of such models is that the wound they possess does not mimic the wound a human develops. Therefore, a novel wound infection model is required which can imitate the human wounds. : This review article mainly discusses various in vitro and in vivo models showing microbial colonization, their advantages and challenges. Apart from these models, there are also present ex vivo wound infection models, but this review mainly focused on various in vitro and in vivo models available for studying wound infection in controlled conditions. This information might be useful in designing an ideal wound infection model for developing an effective wound healing formulation.

scholarly journals Salmonella typhimurium LT2 Catabolizes Propionate via the 2-Methylcitric Acid Cycle

1999 ◽  
Vol 181 (18) ◽  
pp. 5615-5623 ◽  
Author(s):  
Alexander R. Horswill ◽  
Jorge C. Escalante-Semerena
Keyword(s):  
Salmonella Typhimurium ◽  
Negative Ion ◽  
Resonance Spectroscopy ◽  
Ionization Mass ◽  
Wild Type ◽  
Acid Cycle ◽  
Mutant Strains ◽  
Methylcitrate Synthase

ABSTRACT We previously identified the prpBCDE operon, which encodes catabolic functions required for propionate catabolism inSalmonella typhimurium. Results from13C-labeling experiments have identified the route of propionate breakdown and determined the biochemical role of each Prp enzyme in this pathway. The identification of catabolites accumulating in wild-type and mutant strains was consistent with propionate breakdown through the 2-methylcitric acid cycle. Our experiments demonstrate that the α-carbon of propionate is oxidized to yield pyruvate. The reactions are catalyzed by propionyl coenzyme A (propionyl-CoA) synthetase (PrpE), 2-methylcitrate synthase (PrpC), 2-methylcitrate dehydratase (probably PrpD), 2-methylisocitrate hydratase (probably PrpD), and 2-methylisocitrate lyase (PrpB). In support of this conclusion, the PrpC enzyme was purified to homogeneity and shown to have 2-methylcitrate synthase activity in vitro.1H nuclear magnetic resonance spectroscopy and negative-ion electrospray ionization mass spectrometry identified 2-methylcitrate as the product of the PrpC reaction. Although PrpC could use acetyl-CoA as a substrate to synthesize citrate, kinetic analysis demonstrated that propionyl-CoA is the preferred substrate.

Regulatory Role of fnr Gene in Growth and tolA Gene Expression in Salmonella Typhimurium

2021 ◽  
Author(s):  
Nikhil K.C. ◽  
Swagatika Priyadarsini ◽  
M. Pashupathi ◽  
Barkha Ratta ◽  
Meeta Saxena ◽  
...  
Keyword(s):  
Protein Expression ◽  
Salmonella Typhimurium ◽  
Gene Knockout ◽  
Regulatory Gene ◽  
Membrane Integrity ◽  
Global Changes ◽  
Differential Protein Expression ◽  
Differential Protein

Background: Salmonella Typhimurium (S.Typhimurium) adapts to the broad fluctuations of oxygen concentrations encountered in the host. The transition from aerobic to microaerobic/anaerobic condition encountered in the intestine is mainly regulated by fumarate and nitrate reductase (fnr) regulatory gene and aerobic respiratory control A (arcA) gene. Aim is to appraise the role of fnr gene under anaerobic conditions.Methods: In this study, we deleted fnr gene from S.Typhimurium using lambda red-recombinase mediated gene knockout protocol. Further carried out in vitro characterization and analyzed the differential protein expression in wild type (WT) and isogenic Δfnr null mutant (Δfnr) using SDS-PAGE and MALDI-TOF mass spectrometry under anaerobic conditions.Result: In growth competition, WT strain outcompeted the Δfnr and biofilm-forming ability of Δfnr was significantly reduced compared to WT strain. Swimming motility was reduced in Δfnr strain. Besides, differential protein expression revealed the global changes in the expression of many proteins in fnr strain. One differentially expressed protein was identified as TolA, an inner membrane envelope protein. It points out that fnr may regulate the genes responsible for motility and biofilm formation. FNR protein positively regulates TolA, which is important for bacterial virulence, maintenance of membrane integrity, LPS production and replication of bacteria.

Abstract 420: Mrs2 is the Authentic Mammalian Mitochondrial Mg 2+ Channel

2020 ◽  
Vol 127 (Suppl_1) ◽  
Author(s):  
Prema Velusamy ◽  
Shanmughapriya Santhanam
Keyword(s):  
Copy Number ◽  
Mitochondrial Permeability Transition ◽  
Critical Role ◽  
Permeability Transition ◽  
Inner Mitochondrial Membrane ◽  
Metabolic Switch ◽  
Knock Out ◽  
Mitochondrial Copy Number

Magnesium (Mg 2+ ) is an important cation critical for cellular functions and tissue integrity. Mitochondria have been demonstrated to be capable of both accumulate and release Mg 2+ . However, the exact molecular machinery associated with mitochondrial Mg 2+ (mMg 2+ ) influx has not yet been delineated. In the present study we characterized the mammalian mMg 2+ channel, Mrs2 and comprehensively studied its role in energy metabolism. Protein flux, membrane fractionation and STED microscopy studies revealed Mrs2 to localize on the inner mitochondrial membrane with its N and C-terminus in the matrix. Western blot and qPCR analysis confirmed the ubiquitous distribution of Mrs2 in all metabolically active tissues. We adopted lentiviral based strategy to stably knock down (KD) Mrs2 in vitro . Primarily, the use of FRET-based mMg 2+ sensor, MitoMario showed a decreased influx of Mg 2+ into mitochondria in Mrs2 KD cells. This was further confirmed by patch clamping the mitoplasts of the control and Mrs2 KD cells. Because Mg 2+ is an important co-factor in the machineries that replicate, we next assessed the mitochondrial copy number. The decreased influx of mMg 2+ impacted the mitochondrial copy number and electron transport chain (ETC) complex assembly. The defective ETC assembly was marked by increased generation of mitochondrial reactive oxygen species, increased proton leak, decreased ATP levels, and also prompted a metabolic switch from mitochondrial oxidative phosphorylation to glucose oxidation in Mrs2 KD cells. Additionally, Mrs2 KD cells had an increased sensitivity to mROS-induced mitochondrial permeability transition pore opening. To further study the role of Mrs2 in cardiac mitochondrial metabolism and cellular energetics, we have successfully adopted the CRISPR/Cas9 mediated gene targeting strategy to generate the cardiac-specific Mrs2 knock out mouse model. Our study is the first of its kind to characterize the mitochondrial Mg 2+ channel and its impact on mitochondrial copy number and cell viability. Our findings not only identify Mrs2 as an authentic mitochondrial Mg 2+ channel, but also validates the critical role of mMg 2+ in maintaining the bioenergetic state of the cell.

Sign in / Sign up

Export Citation Format

Share Document