scholarly journals Protein folding modulates the adhesion strategy of Gram positive pathogens

2019 ◽  
Author(s):  
Alvaro Alonso-Caballero ◽  
Daniel J. Echelman ◽  
Rafael Tapia-Rojo ◽  
Shubhasis Haldar ◽  
Edward C. Eckels ◽  
...  
Keyword(s):  
Molecular Mechanisms ◽  
Magnetic Tweezers ◽  
Gram Positive ◽  
Covalent Bonds ◽  
Surface Ligands ◽  
Gram Positive Bacteria ◽  
Mucosal Tissues ◽  
Mechanical Shocks ◽  
Thioester Bond ◽  
Amine Ligands

Gram positive bacteria colonize mucosal tissues against large mechanical perturbations, such as coughing, which generate large shear forces that exceed the ability of non-covalent bonds to remain attached. To overcome these challenges, the pathogen Streptococcus pyogenes utilizes the protein Cpa, a pilus tip-end adhesin equipped with a Cys-Gln thioester bond. The reactivity of this bond towards host surface ligands enables covalent anchoring of the bacterium, allowing it to resist large mechanical shocks; however, colonization also requires cell migration and spreading over surfaces. The molecular mechanisms underlying these seemingly incompatible requirements remain unknown. Here, we demonstrate a magnetic tweezers force spectroscopy assay that resolves the dynamics of Cpa thioester bond under force. While folded at forces < 6 pN, Cpa thioester bond reacts reversibly with amine ligands, of common occurrence in inflammation sites; however, mechanical unfolding and exposure to forces higher than 35 pN blocks thioester reactivity entirely. We propose that this folding-coupled thioester reactivity switch allows the adhesin to hop and sample host surface ligands at low force (nomadic mobility phase), and yet gets covalently anchored in place while under mechanical stress (locked phase). We dub such bonds “smart covalent bonds”, adding a novel class to the known repertoire of non-covalent adhesion strategies that include slip bonds, and catch bonds.

scholarly journals CnaA domains in bacterial pili are efficient dissipaters of large mechanical shocks

2016 ◽  
Vol 113 (9) ◽  
pp. 2490-2495 ◽  
Author(s):  
Daniel J. Echelman ◽  
Jorge Alegre-Cebollada ◽  
Carmen L. Badilla ◽  
Chungyu Chang ◽  
Hung Ton-That ◽  
...  
Keyword(s):  
Single Molecule ◽  
Pathogenic Bacteria ◽  
Mechanical Energy ◽  
Bacterial Attachment ◽  
Gram Positive ◽  
Covalent Bonds ◽  
Single Molecule Force Spectroscopy ◽  
Hydrophobic Collapse ◽  
Gram Positive Bacteria ◽  
Mechanical Shocks

Pathogenic bacteria adhere despite severe mechanical perturbations induced by the host, such as coughing. In Gram-positive bacteria, extracellular protein appendages termed pili are necessary for adherence under mechanical stress. However, little is known about the behavior of Gram-positive pili under force. Here, we demonstrate a mechanism by which Gram-positive pili are able to dissipate mechanical energy through mechanical unfolding and refolding of isopeptide bond-delimited polypeptide loops present in Ig-type CnaA domains. Using single-molecule force spectroscopy, we find that these loops of the pilus subunit SpaA of the SpaA-type pilus from Corynebacterium diphtheriae and FimA of the type 2 pilus from Actinomyces oris unfold and extend at forces that are the highest yet reported for globular proteins. Loop refolding is limited by the hydrophobic collapse of the polypeptide and occurs in milliseconds. Remarkably, both SpaA and FimA initially refold to mechanically weaker intermediates that recover strength with time or ligand binding. Based on the high force extensibility, CnaA-containing pili can dissipate ∼28-fold as much energy compared with their inextensible counterparts before reaching forces sufficient to cleave covalent bonds. We propose that efficient mechanical energy dissipation is key for sustained bacterial attachment against mechanical perturbations.

Gram-positive bacteria secrete RNA aptamers to activate human STING for IL-1β release.

2021 ◽  
Author(s):  
Shivalee N Duduskar ◽  
Mohamed Ghait ◽  
Martin Westermann ◽  
Huijuan Guo ◽  
Anuradha Ramoji ◽  
...  
Keyword(s):  
Molecular Mechanisms ◽  
Rna Aptamers ◽  
Inflammasome Activation ◽  
Accessory Gene ◽  
Group B Streptococci ◽  
Gram Positive ◽  
Gram Positive Bacteria ◽  
Accessory Gene Regulator ◽  
New Perspective ◽  
Group B

Molecular mechanisms through which Gram-positive bacteria induce the canonical inflammasome are poorly understood. Here, we studied the effects of Group B streptococci (GBS) and Staphylococcus aureus (SA) on inflammasome activation in human macrophages. Dinucleotide binding small RNA aptamers released by SA and GBS were shown to trigger increased IL-1β generation by inflammasomes. The stimulator of interferon genes-STING as a central mediator of innate immune responses has been identified as the key target of pathogenic RNA. Multi-lamellar lipid bodies (MLBs) produced by SA function as vehicles for the RNA aptamers. Notably, expression of RNA aptamers is controlled by an accessory gene regulator quorum sensing system of the bacteria. These findings have been translated to patients with Gram-positive sepsis showing hallmarks of MLB-RNA-mediated inflammasome activation. Together our findings may provide a new perspective for the pathogenicity of Gram-positive bacterial infection in man.

scholarly journals Anti-staphylococcal activity and mode of action of thioridazine photoproducts

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Tatiana Tozar ◽  
Sofia Santos Costa ◽  
Ana-Maria Udrea ◽  
Viorel Nastasa ◽  
Isabel Couto ◽  
...  
Keyword(s):  
Staphylococcus Aureus ◽  
Antibiotic Resistance ◽  
Molecular Docking ◽  
Infectious Diseases ◽  
Molecular Mechanisms ◽  
Dynamic Surface Tension ◽  
Docking Studies ◽  
Gram Positive ◽  
Dynamic Surface ◽  
Gram Positive Bacteria

Abstract Antibiotic resistance became an increasing risk for population health threatening our ability to fight infectious diseases. The objective of this study was to evaluate the activity of laser irradiated thioridazine (TZ) against clinically-relevant bacteria in view to fight antibiotic resistance. TZ in ultrapure water solutions was irradiated (1–240 min) with 266 nm pulsed laser radiation. Irradiated solutions were characterized by UV–Vis and FTIR absorption spectroscopy, thin layer chromatography, laser-induced fluorescence, and dynamic surface tension measurements. Molecular docking studies were made to evaluate the molecular mechanisms of photoproducts action against Staphylococcus aureus and MRSA. More general, solutions were evaluated for their antimicrobial and efflux inhibitory activity against a panel of bacteria of clinical relevance. We observed an enhanced antimicrobial activity of TZ photoproducts against Gram-positive bacteria. This was higher than ciprofloxacin effects for methicillin- and ciprofloxacin-resistant Staphylococcus aureus. Molecular docking showed the Penicillin-binding proteins PBP3 and PBP2a inhibition by sulforidazine as a possible mechanism of action against Staphylococcus aureus and MRSA strains, respectively. Irradiated TZ reveals possible advantages in the treatment of infectious diseases produced by antibiotic-resistant Gram-positive bacteria. TZ repurposing and its photoproducts, obtained by laser irradiation, show accelerated and low-costs of development if compared to chemical synthesis.

Target recognition, resistance, immunity and genome mining of class II bacteriocins from Gram-positive bacteria

Microbiology ◽  
2011 ◽  
Vol 157 (12) ◽  
pp. 3256-3267 ◽  
Author(s):  
Morten Kjos ◽  
Juan Borrero ◽  
Mona Opsata ◽  
Dagim J. Birri ◽  
Helge Holo ◽  
...  
Keyword(s):  
Molecular Mechanisms ◽  
Genome Mining ◽  
Class Ii ◽  
Biochemical Properties ◽  
Food Preservation ◽  
Target Cells ◽  
Detailed Knowledge ◽  
Genome Sequences ◽  
Gram Positive ◽  
Gram Positive Bacteria

Due to their very potent antimicrobial activity against diverse food-spoiling bacteria and pathogens and their favourable biochemical properties, peptide bacteriocins from Gram-positive bacteria have long been considered promising for applications in food preservation or medical treatment. To take advantage of bacteriocins in different applications, it is crucial to have detailed knowledge on the molecular mechanisms by which these peptides recognize and kill target cells, how producer cells protect themselves from their own bacteriocin (self-immunity) and how target cells may develop resistance. In this review we discuss some important recent progress in these areas for the non-lantibiotic (class II) bacteriocins. We also discuss some examples of how the current wealth of genome sequences provides an invaluable source in the search for novel class II bacteriocins.

scholarly journals Covalent host-targeting by thioester domains of Gram-positive pathogens

2014 ◽  
Vol 70 (a1) ◽  
pp. C848-C848
Author(s):  
Miriam Walden ◽  
John Edwards ◽  
Aleksandra Dziewulska ◽  
Uli Schwarz-Linek ◽  
Mark Banfield
Keyword(s):  
Cell Surface ◽  
Host Cell ◽  
Molecular Mechanisms ◽  
Cell Attachment ◽  
Surface Proteins ◽  
Host Cells ◽  
Covalent Attachment ◽  
Gram Positive ◽  
Covalent Bonds ◽  
Isopeptide Bonds

Gram-positive pathogens are a major concern to global health, with increasing resistance to antimicrobials and the lack of preventative therapeutics. Understanding how these bacteria interact with host cells is vital for the development of novel strategies to combat disease. One of the most crucial steps in infection is adhesion to the host cell. The discovery of complex cell-surface associated proteins, such as pili, has advanced our knowledge of this interaction, however the precise molecular mechanisms underlying this process remain unclear. Structural studies of pili revealed the presence of highly unusual intramolecular covalent bonds between amino acid side chains. These include isopeptide bonds between Lys and Asp/Asn residues, conferring mechanical strength, thermal stability and resistance to proteases [1,2]. In Streptococcus pyogenes pili, the adhesin Spy0125 (or Cpa) interacts with the host cell. It comprises three domains, two of which contain stabilising isopeptide bonds [2,3]. Intriguingly, the third domain contains an extremely rare thioester bond, between a Cys and a Gln residue. A Cys to Ala mutation results in a 75% reduction in adhesion, suggesting that this internal linkage may mediate direct attachment [3]. We have now discovered putative thioester domains (TEDs) in cell-surface proteins of several clinically important pathogens. The only other example of an internal thioester is found in complement proteins, where the reactive bond enables the formation of covalent attachment to pathogens. The presence of these bonds in bacterial proteins suggests the possibility of an as-yet uncharacterised, conserved mechanism of covalent host cell attachment. For a selection of pathogens, we have used mass spectrometry and crystallography to confirm the presence of the covalent link between the Cys and Gln residues within the TEDs. Furthermore, we have identified putative host cell targets of TEDs and confirmed covalent linkages between the TED and the target.

scholarly journals Protein secretion and surface display in Gram-positive bacteria

2012 ◽  
Vol 367 (1592) ◽  
pp. 1123-1139 ◽  
Author(s):  
Olaf Schneewind ◽  
Dominique M. Missiakas
Keyword(s):  
Cell Wall ◽  
Protein Transport ◽  
Surface Display ◽  
Sequence Motifs ◽  
Cell Wall Polysaccharides ◽  
Gram Positive ◽  
Covalent Bonds ◽  
Gram Positive Bacteria ◽  
Cell Wall Peptidoglycan ◽  
Sorting Signals

The cell wall peptidoglycan of Gram-positive bacteria functions as a surface organelle for the transport and assembly of proteins that interact with the environment, in particular, the tissues of an infected host. Signal peptide-bearing precursor proteins are secreted across the plasma membrane of Gram-positive bacteria. Some precursors carry C-terminal sorting signals with unique sequence motifs that are cleaved by sortase enzymes and linked to the cell wall peptidoglycan of vegetative forms or spores. The sorting signals of pilin precursors are cleaved by pilus-specific sortases, which generate covalent bonds between proteins leading to the assembly of fimbrial structures. Other precursors harbour surface (S)-layer homology domains (SLH), which fold into a three-pronged spindle structure and bind secondary cell wall polysaccharides, thereby associating with the surface of specific Gram-positive microbes. Type VII secretion is a non-canonical secretion pathway for WXG100 family proteins in mycobacteria. Gram-positive bacteria also secrete WXG100 proteins and carry unique genes that either contribute to discrete steps in secretion or represent distinctive substrates for protein transport reactions.

Influence of Cell Wall Composition on the Fossilisation of Bacteria and the Implications for the Search for Early Life Forms

1997 ◽  
Vol 161 ◽  
pp. 491-504 ◽  
Author(s):  
Frances Westall
Keyword(s):  
Cell Wall ◽  
Life Forms ◽  
Cation Binding ◽  
Positive Bacterium ◽  
Gram Positive ◽  
Gram Positive Bacteria ◽  
Transmission Electron ◽  
Hydrothermal Sediments ◽  
Identification Of Bacteria ◽  
The Difference

AbstractThe oldest cell-like structures on Earth are preserved in silicified lagoonal, shallow sea or hydrothermal sediments, such as some Archean formations in Western Australia and South Africa. Previous studies concentrated on the search for organic fossils in Archean rocks. Observations of silicified bacteria (as silica minerals) are scarce for both the Precambrian and the Phanerozoic, but reports of mineral bacteria finds, in general, are increasing. The problems associated with the identification of authentic fossil bacteria and, if possible, closer identification of bacteria type can, in part, be overcome by experimental fossilisation studies. These have shown that not all bacteria fossilise in the same way and, indeed, some seem to be very resistent to fossilisation. This paper deals with a transmission electron microscope investigation of the silicification of four species of bacteria commonly found in the environment. The Gram positiveBacillus laterosporusand its spore produced a robust, durable crust upon silicification, whereas the Gram negativePseudomonas fluorescens, Ps. vesicularis, andPs. acidovoranspresented delicately preserved walls. The greater amount of peptidoglycan, containing abundant metal cation binding sites, in the cell wall of the Gram positive bacterium, probably accounts for the difference in the mode of fossilisation. The Gram positive bacteria are, therefore, probably most likely to be preserved in the terrestrial and extraterrestrial rock record.

Microanatomy of the Periplasm of Bacillus Licheniformis

1971 ◽  
Vol 29 ◽  
pp. 262-263
Author(s):  
B.K. Ghosh
Keyword(s):  
Cell Wall ◽  
Plasma Membrane ◽  
Bacillus Licheniformis ◽  
External Environment ◽  
Permeability Barrier ◽  
Periplasmic Space ◽  
Modified Technique ◽  
Gram Positive ◽  
Gram Negative ◽  
Gram Positive Bacteria

Periplasm of bacteria is the space outside the permeability barrier of plasma membrane but enclosed by the cell wall. The contents of this special milieu exterior could be regulated by the plasma membrane from the internal, and by the cell wall from the external environment of the cell. Unlike the gram-negative organism, the presence of this space in gram-positive bacteria is still controversial because it cannot be clearly demonstrated. We have shown the importance of some periplasmic bodies in the secretion of penicillinase from Bacillus licheniformis.In negatively stained specimens prepared by a modified technique (Figs. 1 and 2), periplasmic space (PS) contained two kinds of structures: (i) fibrils (F, 100 Å) running perpendicular to the cell wall from the protoplast and (ii) an array of vesicles of various sizes (V), which seem to have evaginated from the protoplast.

Rapid demonstration of septic or infectious arthritis due to Gram-negative bacteria

1992 ◽  
Vol 50 (1) ◽  
pp. 686-687
Author(s):  
Jacob S. Hanker ◽  
Paul R. Gross ◽  
Beverly L. Giammara
Keyword(s):  
Chronic Arthritis ◽  
Blood Cultures ◽  
Gram Negative Bacteria ◽  
Infectious Arthritis ◽  
Bacterial Arthritis ◽  
Gram Positive ◽  
Gram Negative ◽  
Gram Positive Bacteria

Blood cultures are positive in approximately only 50 per cent of the patients with nongonococcal bacterial infectious arthritis and about 20 per cent of those with gonococcal arthritis. But the concept that gram-negative bacteria could be involved even in chronic arthritis is well-supported. Gram stains are more definitive in staphylococcal arthritis caused by gram-positive bacteria than in bacterial arthritis due to gram-negative bacteria. In the latter situation where gram-negative bacilli are the problem, Gram stains are helpful for 50% of the patients; they are only helpful for 25% of the patients, however, where gram-negative gonococci are the problem. In arthritis due to gram-positive Staphylococci. Gramstained smears are positive for 75% of the patients.

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