scholarly journals Both lipopolysaccharide and lipoteichoic acids potently induce anomalous fibrin amyloid formation: assessment with novel Amytracker™ stains

2018 ◽  
Vol 15 (139) ◽  
pp. 20170941 ◽  
Author(s):  
Etheresia Pretorius ◽  
Martin J. Page ◽  
Lisa Hendricks ◽  
Nondumiso B. Nkosi ◽  
Sven R. Benson ◽  
...  
Keyword(s):  
Inflammatory Diseases ◽  
Molar Ratio ◽  
Amyloid Formation ◽  
Gram Negative Bacteria ◽  
Ferric Ions ◽  
Gram Positive Bacteria ◽  
Low Concentrations ◽  
Trade Name ◽  
Lipoteichoic Acids

In recent work, we discovered that the presence of highly substoichiometric amounts (10 −8 molar ratio) of lipopolysaccharide (LPS) from Gram-negative bacteria caused fibrinogen clotting to lead to the formation of an amyloid form of fibrin. We here show that the broadly equivalent lipoteichoic acids (LTAs) from two species of Gram-positive bacteria have similarly (if not more) potent effects. Using thioflavin T fluorescence to detect amyloid as before, the addition of low concentrations of free ferric ion is found to have similar effects. Luminescent conjugated oligothiophene dyes (LCOs), marketed under the trade name Amytracker™, also stain classical amyloid structures. We here show that they too give very large fluorescence enhancements when clotting is initiated in the presence of the four amyloidogens (LPS, ferric ions and two LTA types). The staining patterns differ significantly as a function of both the amyloidogens and the dyes used to assess them, indicating clearly that the nature of the clots formed is different. This is also the case when clotting is measured viscometrically using thromboelastography. Overall, the data provide further evidence for an important role of bacterial cell wall products in the various coagulopathies that are observable in chronic, inflammatory diseases. The assays may have potential in both diagnostics and therapeutics.

scholarly journals Both lipopolysaccharide and lipoteichoic acids potently induce anomalous fibrin amyloid formation: assessment with novel Amytracker™stains

2017 ◽  
Author(s):  
Etheresia Pretorius ◽  
Martin J Page ◽  
Lisa Hendricks ◽  
Nondumiso B Nkosi ◽  
Sven R Benson ◽  
...  
Keyword(s):  
Inflammatory Diseases ◽  
Molar Ratio ◽  
Amyloid Formation ◽  
Gram Negative Bacteria ◽  
Ferric Ions ◽  
Gram Positive Bacteria ◽  
Low Concentrations ◽  
Trade Name ◽  
Lipoteichoic Acids

AbstractIn recent work, we discovered that the presence of highly substoichiometric amounts (10−8molar ratio) of lipopolysaccharide (LPS) from Gram-negative bacteria caused fibrinogen clotting to lead to the formation of an amyloid form of fibrin. We here show that the broadly equivalent lipoteichoic acids (LTAs) from two species of Gram-positive bacteria have similarly (if not more) potent effects. Using thioflavin T fluorescence to detect amyloid as before, the addition of low concentrations of free ferric ion is found to have similar effects. Luminescent conjugated oligothiophene dyes (LCOs), marketed under the trade name AmytrackerTM, also stain classical amyloid structures. We here show that they too give very large fluorescence enhancements when clotting is initiated in the presence of the four amyloidogens (LPS, ferric ions and two LTA types). The staining patterns differ significantly as a function of both the amyloidogens and the dyes used to assess them, indicating clearly that the nature of the clots formed is different. This is also the case when clotting is measured viscometrically using thromboelastography. Overall, the data provide further evidence for an important role of bacterial cell wall products in the various coagulopathies that are observable in chronic, inflammatory diseases. The assays may have potential in both diagnostics and therapeutics.

scholarly journals Insights into AMS/PCAT transporters from biochemical and structural characterization of a double Glycine motif protease

eLife ◽  
2019 ◽  
Vol 8 ◽  
Author(s):  
Silvia C Bobeica ◽  
Shi-Hui Dong ◽  
Liujie Huo ◽  
Nuria Mazo ◽  
Martin I McLaughlin ◽  
...  
Keyword(s):  
Structural Data ◽  
Leader Peptide ◽  
Gram Negative Bacteria ◽  
Protease Domain ◽  
Peptide Recognition ◽  
Gram Positive Bacteria ◽  
Dual Functional ◽  
Signaling Peptides

The secretion of peptides and proteins is essential for survival and ecological adaptation of bacteria. Dual-functional ATP-binding cassette transporters export antimicrobial or quorum signaling peptides in Gram-positive bacteria. Their substrates contain a leader sequence that is excised by an N-terminal peptidase C39 domain at a double Gly motif. We characterized the protease domain (LahT150) of a transporter from a lanthipeptide biosynthetic operon in Lachnospiraceae and demonstrate that this protease can remove the leader peptide from a diverse set of peptides. The 2.0 Å resolution crystal structure of the protease domain in complex with a covalently bound leader peptide demonstrates the basis for substrate recognition across the entire class of such transporters. The structural data also provide a model for understanding the role of leader peptide recognition in the translocation cycle, and the function of degenerate, non-functional C39-like domains (CLD) in substrate recruitment in toxin exporters in Gram-negative bacteria.

scholarly journals The Recombination Genes addAB Are Not Restricted to Gram-Positive Bacteria: Genetic Analysis of the Recombination Initiation Enzymes RecF and AddAB in Rhizobium etli

2004 ◽  
Vol 186 (23) ◽  
pp. 7905-7913 ◽  
Author(s):  
Jacobo Zuñiga-Castillo ◽  
David Romero ◽  
Jaime M. Martínez-Salazar
Keyword(s):  
Recombination Frequency ◽  
Double Strand Breaks ◽  
Additive Effect ◽  
Gram Negative Bacteria ◽  
Rhizobium Etli ◽  
Gram Positive ◽  
Gram Negative ◽  
Strand Breaks ◽  
Gram Positive Bacteria

ABSTRACT Single-strand gaps (SSGs) and double-strand breaks (DSBs) are the major initiation sites for recombination. In bacteria, the SSGs are repaired by RecFOR, while the DSBs are processed by RecBCD in gram-negative bacteria and AddAB in gram-positive bacteria. Unexpectedly, instead of recBCD genes, the addAB genes were found in members of the α-proteobacteria group (gram negative). Taking Rhizobium etli as a model, the role of recF and addAB genes in homologous recombination and repair of damaged DNA was evaluated. Inactivation of either recF or addA provoked strong sensitivity to UV radiation and mitomycin C, while an additive effect was observed in the recF-addA mutant. The DSBs generated by nalidixic acid caused low viability only in the addA mutant. The recombination frequency of large and small plasmids was reduced in the recF mutant (24- and 36-fold, respectively), whereas a slight decrease (threefold) in the addA mutant was observed. Moreover, an additive effect (47- and 90-fold, respectively) was observed in the double mutant, but it was not as dramatic as that in a recA mutant. Interestingly, the frequency of deletion and Campbell-type recombination was slightly affected in either single or double mutants. These results suggest that another pathway exists that allows plasmid and Campbell-type recombination in the absence of recF and addA genes.

The role of biosynthesized silver nanoparticles in antimicrobial mechanisms

2021 ◽  
Vol 22 ◽  
Author(s):  
Bianca PizzornoBackx ◽  
Mayara Santana dos Santos ◽  
Otávio Augusto Leitão dos Santos ◽  
Sérgio Antunes Filho
Keyword(s):  
Silver Nanoparticles ◽  
Green Synthesis ◽  
Antimicrobial Properties ◽  
New Drugs ◽  
Gram Negative Bacteria ◽  
New Materials ◽  
Gram Negative ◽  
Gram Positive Bacteria ◽  
Emergence Of Resistance

: Nanotechnology is an area of science able to develop new materials. The relation between nanotechnology and microbiology is essential for the development of new drugs and vaccines. The main advantage of blend in both areas is to associate the latest technology to obtain new ways to solve problems related to microorganisms. This review seeks to investigate nanoparticle formation's antimicrobial properties, primarily when connected to the green synthesis of silver nanoparticles. The development of new sustainable methods for nanoparticle production has been instrumental in designing alternative, non-toxic, energy-friendly, and environmentally friendly routes. In this sense, it is necessary to study silver nanoparticles' green synthesis concerning their antimicrobial properties. Antimicrobial mechanisms of silver nanoparticles demonstrate efficiency to gram-positive bacteria, gram-negative bacteria, fungi, viruses, and parasites. However, attention is needed with the emergence of resistance to these antimicrobials. This article seeks to relate the parameters of green silver-based nanosystems with the efficiency of antimicrobial activity.

scholarly journals Role of Porins in Iron Uptake by Mycobacterium smegmatis

2010 ◽  
Vol 192 (24) ◽  
pp. 6411-6417 ◽  
Author(s):  
Christopher M. Jones ◽  
Michael Niederweis
Keyword(s):  
Outer Membrane ◽  
Mycobacterium Smegmatis ◽  
Iron Homeostasis ◽  
Iron Acquisition ◽  
Gram Negative Bacteria ◽  
Ferric Ions ◽  
Intracellular Iron ◽  
High Iron ◽  
Hydrophilic Solutes

ABSTRACT Many bacteria rely on siderophores to extract iron from the environment. However, acquisition of iron-loaded siderophores is dependent on high-affinity uptake systems that are not produced under high-iron conditions. The fact that bacteria are able to maintain iron homeostasis in the absence of siderophores indicates that alternative iron acquisition systems exist. It has been speculated that such low-affinity uptake of iron in Gram-negative bacteria includes diffusion of iron ions or chelates across the outer membrane through porins. The outer membrane of the saprophytic Mycobacterium smegmatis contains the Msp family of porins, which enable the diffusion of small and hydrophilic solutes, such as monosaccharides, amino acids, and phosphate. However, it is unknown how cations cross the outer membrane of mycobacteria. Here, we show that the Msp porins of M. smegmatis are involved in the acquisition of soluble iron under high-iron conditions. Uptake of ferric ions by a triple porin mutant was reduced compared to wild-type (wt) M. smegmatis. An intracellular iron reporter indicated that derepression of iron-responsive genes occurs at higher iron concentrations in the porin mutant. This was consistent with the finding that the porin mutant produced more siderophores under low-iron conditions than wt M. smegmatis. In contrast, uptake of the exochelin MS, the main siderophore of M. smegmatis, was not affected by the lack of porins, indicating that a specific outer membrane siderophore receptor exists. These results provide, to our knowledge, the first experimental evidence that general porins are indeed the outer membrane conduit of low-affinity iron acquisition systems in bacteria.

scholarly journals Lipoproteins of Gram-Positive Bacteria: Key Players in the Immune Response and Virulence

2016 ◽  
Vol 80 (3) ◽  
pp. 891-903 ◽  
Author(s):  
Minh Thu Nguyen ◽  
Friedrich Götz
Keyword(s):  
Immune Response ◽  
Gram Negative Bacteria ◽  
Gram Positive ◽  
Gram Negative ◽  
Content Type ◽  
Gram Positive Bacteria ◽  
Key Players ◽  
Toll Like Receptor 2 ◽  
Number Of Publications

SUMMARYSince the discovery in 1973 of the first of the bacterial lipoproteins (Lpp) inEscherichia coli, Braun's lipoprotein, the ever-increasing number of publications indicates the importance of these proteins. Bacterial Lpp belong to the class of lipid-anchored proteins that in Gram-negative bacteria are anchored in both the cytoplasmic and outer membranes and in Gram-positive bacteria are anchored only in the cytoplasmic membrane. In contrast to the case for Gram-negative bacteria, in Gram-positive bacteria lipoprotein maturation and processing are not vital. Physiologically, Lpp play an important role in nutrient and ion acquisition, allowing particularly pathogenic species to better survive in the host. Bacterial Lpp are recognized by Toll-like receptor 2 (TLR2) of the innate immune system. The important role of Lpp in Gram-positive bacteria, particularly in the phylumFirmicutes, as key players in the immune response and pathogenicity has emerged only in recent years. In this review, we address the role of Lpp in signaling and modulating the immune response, in inflammation, and in pathogenicity. We also address the potential of Lpp as promising vaccine candidates.

scholarly journals Macrophage migration inhibitory factor: molecular, cellular and genetic aspects of a key neuroendocrine molecule

2004 ◽  
Vol 182 (1) ◽  
pp. 1-9 ◽  
Author(s):  
RP Donn ◽  
DW Ray
Keyword(s):  
Migration Inhibitory Factor ◽  
Macrophage Migration Inhibitory Factor ◽  
Inflammatory Diseases ◽  
Inhibitory Factor ◽  
Target Cells ◽  
Macrophage Migration ◽  
Signalling Molecules ◽  
Functional Polymorphisms ◽  
Low Concentrations

The immunological and neuroendocrine properties of macrophage migration inhibitory factor (MIF) are diverse. In this article we review the known cellular, molecular and genetic properties of MIF that place it as a key regulatory cytokine, acting within both the innate and adaptive immune responses.The unexpected and paradoxical induction of MIF secretion by low concentrations of glucocorticoids is explored. The role of MIF as a locally acting modulator of glucocorticoid sensitivity within foci of inflammation is also discussed. MIF has no homology with any other pro-inflammatory cytokine and until recently lacked a recognised transmembrane receptor. MIF has also been shown to be directly taken up into target cells and to interact with intracellular signalling molecules, including the Jun activation domain-binding protein Jab-1.Comprehensive analysis of the MIF gene has identified important functional polymorphisms and a series of genetic studies has revealed both association and linkage of MIF with inflammatory diseases. Altered MIF regulation may therefore be pivotal to acquiring chronic inflammation following an innate immune response.

scholarly journals Fluoroquinolone Metalloantibiotics to Bypass Antimicrobial Resistance Mechanisms: Decreased Permeation through Porins

Membranes ◽  
2020 ◽  
Vol 11 (1) ◽  
pp. 3
Author(s):  
Mariana Ferreira ◽  
Carla F. Sousa ◽  
Paula Gameiro
Keyword(s):  
Antimicrobial Resistance ◽  
Membrane Permeability ◽  
Resistance Mechanism ◽  
Resistance Mechanisms ◽  
Gram Negative Bacteria ◽  
Gram Negative ◽  
Gram Positive Bacteria ◽  
Specific Association ◽  
Location Association

Fluoroquinolones (FQs) are broad-spectrum antibiotics largely used in the clinical practice against Gram-negative and some Gram-positive bacteria. Nevertheless, bacteria have developed several antimicrobial resistance mechanisms against such class of antibiotics. Ternary complexes of FQs, copper(II) and phenanthroline, known as metalloantibiotics, arise in an attempt to counteract an antibiotic resistance mechanism related to low membrane permeability. These metalloantibiotics seem to use an alternative influx route, independent of porins. The translocation pathways of five FQs and its metalloantibiotics were studied through biophysical experiments, allowing us to infer about the role of OmpF porin in the influx. The FQ-OmpF interaction was assessed in mimetic membrane systems differing on the lipidic composition, disclosing no interference of the lipidic composition. The drug-porin interaction revealed similar values for the association constants of FQs and metalloantibiotics with native OmpF. Therefore, OmpF mutants and specific quenchers were used to study the location-association relationship, comparing a free FQ and its metalloantibiotic. The free FQ revealed a specific association, with preference for residues on the centre of OmpF, while the metalloantibiotic showed a random interaction. Thereby, metalloantibiotics may be an alternative to pure FQs, being able to overcome some antimicrobial resistance mechanism of Gram-negative bacteria related to decreased membrane permeability.

scholarly journals Lipoteichoic Acids from Lactobacillus johnsonii Strain La1 and Lactobacillus acidophilus Strain La10 Antagonize the Responsiveness of Human Intestinal Epithelial HT29 Cells to Lipopolysaccharide and Gram-Negative Bacteria

2002 ◽  
Vol 70 (4) ◽  
pp. 2057-2064 ◽  
Author(s):  
Karine Vidal ◽  
Anne Donnet-Hughes ◽  
Dominique Granato
Keyword(s):  
Human Milk ◽  
Proinflammatory Cytokines ◽  
Lactobacillus Acidophilus ◽  
Gram Negative Bacteria ◽  
Intestinal Epithelial ◽  
Lactobacillus Johnsonii ◽  
Gram Positive ◽  
Gram Negative ◽  
Gram Positive Bacteria ◽  
Lipoteichoic Acids

ABSTRACT Intestinal epithelial cells (IECs) respond to lipopolysaccharide (LPS) from gram-negative bacteria in the presence of the soluble form of CD14 (sCD14), a major endotoxin receptor. Since sCD14 is also known to interact with gram-positive bacteria and their components, we looked at whether sCD14 could mediate their effects on human IECs. To this end, we examined the production of proinflammatory cytokines following exposure of the IECs to specific gram-positive bacteria or their lipoteichoic acids (LTAs) in the absence and presence of human milk as a source of sCD14. In contrast to LPS from Escherichia coli or Salmonella enteritidis, neither the gram-positive bacteria Lactobacillus johnsonii strain La1 and Lactobacillus acidophilus strain La10 nor their LTAs stimulated IECs, even in the presence of sCD14. However, both LTAs inhibited the sCD14-mediated LPS responsiveness of IECs. We have previously hypothesized that sCD14 in human milk is a means by which the neonate gauges the bacterial load in the intestinal lumen and liberates protective proinflammatory cytokines from IECs. The present observations suggest that gram-positive organisms, via their LTAs, temper this response and prevent an exaggerated inflammatory response.

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