Publications by authors named "Cécile Feuillie"

20 Publications

  • Page 1 of 1

binds to the N-terminal region of corneodesmosin to adhere to the stratum corneum in atopic dermatitis.

Proc Natl Acad Sci U S A 2021 01;118(1)

Department of Microbiology, Moyne Institute of Preventive Medicine, School of Genetics and Microbiology, Trinity College Dublin, Dublin 2, Ireland;

colonizes the skin of the majority of patients with atopic dermatitis (AD), and its presence increases disease severity. Adhesion of to corneocytes in the stratum corneum is a key initial event in colonization, but the bacterial and host factors contributing to this process have not been defined. Here, we show that interacts with the host protein corneodesmosin. Corneodesmosin is aberrantly displayed on the tips of villus-like projections that occur on the surface of AD corneocytes as a result of low levels of skin humectants known as natural moisturizing factor (NMF). An mutant deficient in fibronectin binding protein B (FnBPB) and clumping factor B (ClfB) did not bind to corneodesmosin in vitro. Using surface plasmon resonance, we found that FnBPB and ClfB proteins bound with similar affinities. The binding site was localized to the N-terminal glycine-serine-rich region of corneodesmosin. Atomic force microscopy showed that the N-terminal region was present on corneocytes containing low levels of NMF and that blocking it with an antibody inhibited binding of individual cells to corneocytes. Finally, we found that mutants deficient in FnBPB or ClfB have a reduced ability to adhere to low-NMF corneocytes from patients. In summary, we show that FnBPB and ClfB interact with the accessible N-terminal region of corneodesmosin on AD corneocytes, allowing to take advantage of the aberrant display of corneodesmosin that accompanies low NMF in AD. This interaction facilitates the characteristic strong binding of to AD corneocytes.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1073/pnas.2014444118DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7817190PMC
January 2021

The microbial adhesive arsenal deciphered by atomic force microscopy.

Nanoscale 2020 Dec 8;12(47):23885-23896. Epub 2020 Dec 8.

Université de Lorraine, CNRS, LIEC, F-54000 Nancy, France.

Microbes employ a variety of strategies to adhere to abiotic and biotic surfaces, as well as host cells. In addition to their surface physicochemical properties (e.g. charge, hydrophobic balance), microbes produce appendages (e.g. pili, fimbriae, flagella) and express adhesion proteins embedded in the cell wall or cell membrane, with adhesive domains targeting specific ligands or chemical properties. Atomic force microscopy (AFM) is perfectly suited to deciphering the adhesive properties of microbial cells. Notably, AFM imaging has revealed the cell wall topographical organization of live cells at unprecedented resolution, and AFM has a dual capability to probe adhesion at the single-cell and single-molecule levels. AFM is thus a powerful tool for unravelling the molecular mechanisms of microbial adhesion at scales ranging from individual molecular interactions to the behaviours of entire cells. In this review, we cover some of the major breakthroughs facilitated by AFM in deciphering the microbial adhesive arsenal, including the exciting development of anti-adhesive strategies.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1039/d0nr07492fDOI Listing
December 2020

High Speed AFM and NanoInfrared Spectroscopy Investigation of Aβ Peptide Variants and Their Interaction With POPC/SM/Chol/GM1 Model Membranes.

Front Mol Biosci 2020 9;7:571696. Epub 2020 Sep 9.

CBMN, CNRS UMR 5248, IPB, Université de Bordeaux, Pessac, France.

Due to an aging population, neurodegenerative diseases such as Alzheimer's disease (AD) have become a major health issue. In the case of AD, Aβ peptides have been identified as one of the markers of the disease with the formation of senile plaques via their aggregation, and could play a role in memory impairment and other tragic syndromes associated with the disease. Many studies have shown that not only the morphology and structure of Aβ peptide assembly are playing an important role in the formation of amyloid plaques, but also the interactions between Aβ and the cellular membrane are crucial regarding the aggregation processes and toxicity of the amyloid peptides. Despite the increasing amount of information on AD associated amyloids and their toxicity, the molecular mechanisms involved still remain unclear and require in-depth investigation at the local scale to clearly decipher the role of the sequence of the amyloid peptides, of their secondary structures, of their oligomeric states, and of their interactions with lipid membranes. In this original study, through the use of Atomic Force Microscopy (AFM) related-techniques, high-speed AFM and nanoInfrared AFM, we tried to unravel at the nanoscale the link between aggregation state, structure and interaction with membranes in the amyloid/membrane interaction. Using three mutants of Aβ peptides, L34T, oG37C, and WT Aβ peptides, with differences in morphology, structure and assembly process, as well as model lipidic membranes whose composition and structure allow interactions with the peptides, our AFM study coupling high spatial and temporal resolution and nanoscale structure information clearly evidences a local correlation between the secondary structure of the peptides, their fibrillization kinetics and their interactions with model membranes. Membrane disruption is associated to small transient oligomeric entities in the early stages of aggregation that strongly interact with the membrane, and present an antiparallel β-sheet secondary structure. The strong effect on membrane integrity that exists when these oligomeric Aβ peptides interact with membranes of a particular composition could be a lead for therapeutic studies.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.3389/fmolb.2020.571696DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7510551PMC
September 2020

Localized incorporation of outer membrane components in the pathogen .

EMBO J 2019 03 11;38(5). Epub 2019 Jan 11.

Research Unit in Biology of Microorganisms (URBM), Narilis University of Namur (UNamur), Namur, Belgium

The zoonotic pathogen is part of the Rhizobiales, which are alpha-proteobacteria displaying unipolar growth. Here, we show that this bacterium exhibits heterogeneity in its outer membrane composition, with clusters of rough lipopolysaccharide co-localizing with the essential outer membrane porin Omp2b, which is proposed to allow facilitated diffusion of solutes through the porin. We also show that the major outer membrane protein Omp25 and peptidoglycan are incorporated at the new pole and the division site, the expected growth sites. Interestingly, lipopolysaccharide is also inserted at the same growth sites. The absence of long-range diffusion of main components of the outer membrane could explain the apparent immobility of the Omp2b clusters, as well as unipolar and mid-cell localizations of newly incorporated outer membrane proteins and lipopolysaccharide. Unipolar growth and limited mobility of surface structures also suggest that new surface variants could arise in a few generations without the need of diluting pre-existing surface antigens.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.15252/embj.2018100323DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6396147PMC
March 2019

Bacterial Sexuality at the Nanoscale.

Nano Lett 2018 09 31;18(9):5821-5826. Epub 2018 Aug 31.

Louvain Institute of Biomolecular Science and Technology , Université catholique de Louvain , Croix du Sud, 4-5 , B-1348 Louvain-la-Neuve , Belgium.

Understanding the basic mechanisms of bacterial sexuality is an important topic in current microbiology and biotechnology. While classical methods used to study gene transfer provide information on whole cell populations, nanotechnologies offer new opportunities for analyzing the behavior of individual mating partners. We introduce an innovative atomic force microscopy (AFM) platform to study and mechanically control DNA transfer between single bacteria, focusing on the large conjugative pXO16 plasmid of the Gram-positive bacterium Bacillus thuringiensis. We demonstrate that the adhesion forces between single donor and recipient cells are very strong (∼2 nN). Using a mutant plasmid, we find that these high forces are mediated by a pXO16 aggregation locus that contains two large surface protein genes. Notably, we also show that AFM can be used to mechanically induce plasmid transfer between single partners, revealing that transfer is very fast (<15 min) and triggers major cell surface changes in transconjugant cells. We anticipate that the single-cell technology developed here will enable researchers to mechanically control gene transfer among a wide range of Gram-positive and Gram-negative bacterial species and to understand the molecular forces involved. Also, the method could be useful in nanomedicine for the design of antiadhesion compounds capable of preventing intimate cell-cell contacts, therefore providing a means to control the resistance and virulence of bacterial pathogens.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1021/acs.nanolett.8b02463DOI Listing
September 2018

Adhesion of Staphylococcus aureus to Corneocytes from Atopic Dermatitis Patients Is Controlled by Natural Moisturizing Factor Levels.

mBio 2018 08 14;9(4). Epub 2018 Aug 14.

Institute of Life Sciences, Université Catholique de Louvain, Louvain-la-Neuve, Belgium

The bacterial pathogen plays an important role in atopic dermatitis (AD), a chronic disorder that mostly affects children. Colonization of the skin of AD patients by exacerbates the disease, but the molecular determinants of the bacterium-skin adhesive interactions are poorly understood. Specifically, reduced levels of natural moisturizing factor (NMF) in the stratum corneum have been shown to be associated with more severe AD symptoms, but whether this is directly related to adhesion is still an open question. Here, we demonstrate a novel relationship between NMF expression in AD skin and strength of bacterial adhesion. Low-NMF corneocytes, unlike high-NMF ones, are covered by a dense layer of nanoscale villus protrusions. bacteria isolated from AD skin bind much more strongly to corneocytes when the NMF level is reduced. Strong binding forces originate from a specific interaction between the bacterial adhesion clumping factor B (ClfB) and skin ligands. Remarkably, mechanical tension dramatically strengthens ClfB-mediated adhesion, as observed with catch bonds, demonstrating that physical stress plays a role in promoting colonization of AD skin by Collectively, our findings demonstrate that patient NMF levels regulate the strength of -corneocyte adhesion, the first step in skin colonization, and suggest that the ClfB binding mechanism could represent a potential target for new therapeutic treatments. Bacterium-skin interactions play important roles in skin disorders, yet their molecular details are poorly understood. In this study, we decipher the molecular forces at play during adhesion of to skin corneocytes in the clinically important context of atopic dermatitis (AD), also known as eczema. We identify a unique relationship between the level of natural moisturizing factor (NMF) in the skin and the strength of bacterium-corneocyte adhesion. Bacterial adhesion is primarily mediated by the surface protein clumping factor B (ClfB) and is enhanced by physical stress, highlighting the role of protein mechanobiology in skin colonization. Similar to a catch bond behavior, this mechanism represents a promising target for the development of novel antistaphylococcal agents.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1128/mBio.01184-18DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6094479PMC
August 2018

Binding of Nucleic Acid Components to the Serpentinite-Hosted Hydrothermal Mineral Brucite.

Astrobiology 2018 08 26;18(8):989-1007. Epub 2018 Jul 26.

3 Scuola Normale Superiore , Pisa, Italy .

The adsorption of nucleic acid components onto the serpentinite-hosted hydrothermal mineral brucite has been investigated experimentally by determining the equilibrium adsorption isotherms in aqueous solution. Thermodynamic characterization of the adsorption data has been performed using the extended triple-layer model (ETLM) to establish a model for the stoichiometry and equilibrium constants of surface complexes. Infrared characterization of the molecule-mineral complexes has helped gain insight into the molecular functional groups directly interacting with the mineral surface. Quantum mechanical calculations have been carried out to identify the possible complexes formed on surfaces by nucleic acid components and their binding configurations on mineral surfaces, both in the presence of water molecules and in water-free conditions. The results indicate that brucite favors adsorption of nucleotides with respect to nucleosides and nucleobases from dilute aqueous environments. The surface of this mineral is able to induce well-defined orientations of the molecules through specific molecule-mineral interactions. This result suggests plausible roles of the mineral brucite in assisting prebiotic molecular self-organization. Furthermore, the detection of the infrared spectroscopic features of such building blocks of life adsorbed on brucite at very low degrees of coverage provides important support to life detection investigations.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1089/ast.2017.1784DOI Listing
August 2018

Mechanical Forces Guiding Staphylococcus aureus Cellular Invasion.

ACS Nano 2018 04 10;12(4):3609-3622. Epub 2018 Apr 10.

Institute of Life Sciences , Université catholique de Louvain , Croix du Sud, 4-5, bte L7.07.06 , B-1348 Louvain-la-Neuve , Belgium.

Staphylococcus aureus can invade various types of mammalian cells, thereby enabling it to evade host immune defenses and antibiotics. The current model for cellular invasion involves the interaction between the bacterial cell surface located fibronectin (Fn)-binding proteins (FnBPA and FnBPB) and the α5β1 integrin in the host cell membrane. While it is believed that the extracellular matrix protein Fn serves as a bridging molecule between FnBPs and integrins, the fundamental forces involved are not known. Using single-cell and single-molecule experiments, we unravel the molecular forces guiding S. aureus cellular invasion, focusing on the prototypical three-component FnBPA-Fn-integrin interaction. We show that FnBPA mediates bacterial adhesion to soluble Fn via strong forces (∼1500 pN), consistent with a high-affinity tandem β-zipper, and that the FnBPA-Fn complex further binds to immobilized α5β1 integrins with a strength much higher than that of the classical Fn-integrin bond (∼100 pN). The high mechanical stability of the Fn bridge favors an invasion model in which Fn binding by FnBPA leads to the exposure of cryptic integrin-binding sites via allosteric activation, which in turn engage in a strong interaction with integrins. This activation mechanism emphasizes the importance of protein mechanobiology in regulating bacterial-host adhesion. We also find that Fn-dependent adhesion between S. aureus and endothelial cells strengthens with time, suggesting that internalization occurs within a few minutes. Collectively, our results provide a molecular foundation for the ability of FnBPA to trigger host cell invasion by S. aureus and offer promising prospects for the development of therapeutic approaches against intracellular pathogens.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1021/acsnano.8b00716DOI Listing
April 2018

Force-Induced Strengthening of the Interaction between Clumping Factor B and Loricrin.

mBio 2017 Dec 5;8(6). Epub 2017 Dec 5.

Institute of Life Sciences, Université Catholique de Louvain, Louvain-la-Neuve, Belgium

Bacterial pathogens that colonize host surfaces are subjected to physical stresses such as fluid flow and cell surface contacts. How bacteria respond to such mechanical cues is an important yet poorly understood issue. uses a repertoire of surface proteins to resist shear stress during the colonization of host tissues, but whether their adhesive functions can be modulated by physical forces is not known. Here, we show that the interaction of clumping factor B (ClfB) with the squamous epithelial cell envelope protein loricrin is enhanced by mechanical force. We find that ClfB mediates adhesion to loricrin through weak and strong molecular interactions both in a laboratory strain and in a clinical isolate. Strong forces (~1,500 pN), among the strongest measured for a receptor-ligand bond, are consistent with a high-affinity "dock, lock, and latch" binding mechanism involving dynamic conformational changes in the adhesin. Notably, we demonstrate that the strength of the ClfB-loricrin bond increases as mechanical force is applied. These findings favor a two-state model whereby bacterial adhesion to loricrin is enhanced through force-induced conformational changes in the ClfB molecule, from a weakly binding folded state to a strongly binding extended state. This force-sensitive mechanism may provide with a means to finely tune its adhesive properties during the colonization of host surfaces, helping cells to attach firmly under high shear stress and to detach and spread under low shear stress. colonizes the human skin and the nose and can cause various disorders, including superficial skin lesions and invasive infections. During nasal colonization, the surface protein clumping factor B (ClfB) binds to the squamous epithelial cell envelope protein loricrin, but the molecular interactions involved are poorly understood. Here, we unravel the molecular mechanism guiding the ClfB-loricrin interaction. We show that the ClfB-loricrin bond is remarkably strong, consistent with a high-affinity "dock, lock, and latch" binding mechanism. We discover that the ClfB-loricrin interaction is enhanced under tensile loading, thus providing evidence that the function of an surface protein can be activated by physical stress.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1128/mBio.01748-17DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5717387PMC
December 2017

Nucleation and growth of a bacterial functional amyloid at single-fiber resolution.

Nat Chem Biol 2017 Aug 19;13(8):902-908. Epub 2017 Jun 19.

Structural Biology Brussels, Vrije Universiteit Brussel, Brussels, Belgium.

Curli are functional amyloids produced by proteobacteria like Escherichia coli as part of the extracellular matrix that holds cells together into biofilms. The molecular events that occur during curli nucleation and fiber extension remain largely unknown. Combining observations from curli amyloidogenesis in bulk solutions with real-time in situ nanoscopic imaging at the single-fiber level, we show that curli display polar growth, and we detect two kinetic regimes of fiber elongation. Single fibers exhibit stop-and-go dynamics characterized by bursts of steady-state growth alternated with periods of stagnation. At high subunit concentrations, fibers show constant, unperturbed burst growth. Curli follow a one-step nucleation process in which monomers contemporaneously fold and oligomerize into minimal fiber units that have growth characteristics identical to those of the mature fibrils. Kinetic data and interaction studies of curli fibrillation in the presence of the natural inhibitor CsgC show that the inhibitor binds curli fibers and predominantly acts at the level of fiber elongation.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1038/nchembio.2413DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5580806PMC
August 2017

Clumping Factor B Promotes Adherence of Staphylococcus aureus to Corneocytes in Atopic Dermatitis.

Infect Immun 2017 06 23;85(6). Epub 2017 May 23.

Department of Microbiology, Moyne Institute of Preventive Medicine, School of Genetics and Microbiology, Trinity College Dublin, Dublin, Ireland

skin infection is a frequent and recurrent problem in children with the common inflammatory skin disease atopic dermatitis (AD). colonizes the skin of the majority of children with AD and exacerbates the disease. The first step during colonization and infection is bacterial adhesion to the cornified envelope of corneocytes in the outer layer, the stratum corneum. Corneocytes from AD skin are structurally different from corneocytes from normal healthy skin. The objective of this study was to identify bacterial proteins that promote the adherence of to AD corneocytes. strains from clonal complexes 1 and 8 were more frequently isolated from infected AD skin than from the nasal cavity of healthy children. AD strains had increased ClfB ligand binding activity compared to normal nasal carriage strains. Adherence of single bacteria to corneocytes from AD patients was studied using atomic force microscopy. Bacteria expressing ClfB recognized ligands distributed over the entire corneocyte surface. The ability of an isogenic ClfB-deficient mutant to adhere to AD corneocytes compared to that of its parent clonal complex 1 clinical strain was greatly reduced. ClfB from clonal complex 1 strains had a slightly higher binding affinity for its ligand than ClfB from strains from other clonal complexes. Our results provide new insights into the first step in the establishment of colonization in AD patients. ClfB is a key adhesion molecule for the interaction of with AD corneocytes and represents a target for intervention.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1128/IAI.00994-16DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5442637PMC
June 2017

Molecular interactions and inhibition of the staphylococcal biofilm-forming protein SdrC.

Proc Natl Acad Sci U S A 2017 04 20;114(14):3738-3743. Epub 2017 Mar 20.

Institute of Life Sciences, Université Catholique de Louvain, B-1348 Louvain-la-Neuve, Belgium;

forms biofilms on indwelling medical devices using a variety of cell-surface proteins. There is growing evidence that specific homophilic interactions between these proteins represent an important mechanism of cell accumulation during biofilm formation, but the underlying molecular mechanisms are still not well-understood. Here we report the direct measurement of homophilic binding forces by the serine-aspartate repeat protein SdrC and their inhibition by a peptide. Using single-cell and single-molecule force measurements, we find that SdrC is engaged in low-affinity homophilic bonds that promote cell-cell adhesion. Low-affinity intercellular adhesion may play a role in favoring biofilm dynamics. We show that SdrC also mediates strong cellular interactions with hydrophobic surfaces, which are likely to be involved in the initial attachment to biomaterials, the first stage of biofilm formation. Furthermore, we demonstrate that a peptide derived from β-neurexin is a powerful competitive inhibitor capable of efficiently blocking surface attachment, homophilic adhesion, and biofilm accumulation. Molecular modeling suggests that this blocking activity may originate from binding of the peptide to a sequence of SdrC involved in homophilic interactions. Our study opens up avenues for understanding the role of homophilic interactions in staphylococcal adhesion, and for the design of new molecules to prevent biofilm formation during infection.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1073/pnas.1616805114DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5389287PMC
April 2017

Forces between Staphylococcus aureus and human skin.

Nanoscale Horiz 2016 Jul 6;1(4):298-303. Epub 2016 May 6.

Institute of Life Sciences, Université catholique de Louvain, Croix du Sud, 4-5, bte L7.07.06, B-1348 Louvain-la-Neuve, Belgium.

Characterization of the molecular interactions between microbial cells and the human skin is essential to understand the functions of the skin microbiome, and to gain insight into the molecular basis of skin disorders. Although various molecular approaches have been used to study microbe-skin interactions, the underlying molecular forces were not accessible to study. Here we present a novel atomic force microscopy approach to localize and quantify the nanoscale interaction forces between the bacterial pathogen Staphylococcus aureus and human skin. A method combining nanoscale multiparametric imaging with single bacterial probes is developed to map simultaneously the topography and bacterial-binding properties of corneocytes at high spatiotemporal resolution. Further quantification of the forces between bacteria and corneocytes is achieved using single-cell force spectroscopy. The results show that the S. aureus-skin adhesion is strong (∼500 pN) and originates from multiple specific bonds between adhesins on the bacterial cell surface and target ligands on the corneocyte surface. Applicable to a wide variety of microbes and skin cells, our methodology offers exciting prospects for understanding the molecular details of skin colonization and infection.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1039/c6nh00057fDOI Listing
July 2016

Sticky Matrix: Adhesion Mechanism of the Staphylococcal Polysaccharide Intercellular Adhesin.

ACS Nano 2016 03 23;10(3):3443-52. Epub 2016 Feb 23.

Institute of Life Sciences, Université catholique de Louvain , Croix du Sud, 4-5, bte L7.07.06., B-1348 Louvain-la-Neuve, Belgium.

The development of bacterial biofilms on surfaces leads to hospital-acquired infections that are difficult to fight. In Staphylococci, the cationic polysaccharide intercellular adhesin (PIA) forms an extracellular matrix that connects the cells together during biofilm formation, but the molecular forces involved are unknown. Here, we use advanced force nanoscopy techniques to unravel the mechanism of PIA-mediated adhesion in a clinically relevant methicillin-resistant Staphylococcus aureus (MRSA) strain. Nanoscale multiparametric imaging of the structure, adhesion, and elasticity of bacteria expressing PIA shows that the cells are surrounded by a soft and adhesive matrix of extracellular polymers. Cell surface softness and adhesion are dramatically reduced in mutant cells deficient for the synthesis of PIA or under unfavorable growth conditions. Single-cell force spectroscopy demonstrates that PIA promotes cell-cell adhesion via the multivalent electrostatic interaction with polyanionic teichoic acids on the S. aureus cell surface. This binding mechanism rationalizes, at the nanoscale, the well-known ability of PIA to strengthen intercellular adhesion in staphylococcal biofilms. Force nanoscopy offers promising prospects for understanding the fundamental forces in antibiotic-resistant biofilms and for designing anti-adhesion compounds targeting matrix polymers.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1021/acsnano.5b07515DOI Listing
March 2016

Raman spectroscopy in biomedicine: new advances in SERRS cancer imaging.

Authors:
Cécile Feuillie

Ann Transl Med 2015 Dec;3(22):347

Geophysical laboratory, Carnegie Institution of Washington, Washington, DC 20015, USA.

View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.3978/j.issn.2305-5839.2015.09.34DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4701518PMC
December 2015

Forces guiding staphylococcal adhesion.

J Struct Biol 2017 01 17;197(1):65-69. Epub 2015 Dec 17.

Université catholique de Louvain, Institute of Life Sciences, Croix du Sud 4-5, bte L7.07.06, B-1348 Louvain-la-Neuve, Belgium; Walloon Excellence in Life Sciences and Biotechnology (WELBIO), Belgium. Electronic address:

Staphylococcus epidermidis and Staphylococcus aureus are two important nosocomial pathogens that form biofilms on indwelling medical devices. Biofilm infections are difficult to fight as cells within the biofilm show increased resistance to antibiotics. Our understanding of the molecular interactions driving bacterial adhesion, the first stage of biofilm formation, has long been hampered by the paucity of appropriate force-measuring techniques. In this minireview, we discuss how atomic force microscopy techniques have enabled to shed light on the molecular forces at play during staphylococcal adhesion. Specific highlights include the study of the binding mechanisms of adhesion molecules by means of single-molecule force spectroscopy, the measurement of the forces involved in whole cell interactions using single-cell force spectroscopy, and the probing of the nanobiophysical properties of living bacteria via multiparametric imaging. Collectively, these findings emphasize the notion that force and function are tightly connected in staphylococcal adhesion.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.jsb.2015.12.009DOI Listing
January 2017

Detection of DNA sequences refractory to PCR amplification using a biophysical SERRS assay (Surface Enhanced Resonant Raman Spectroscopy).

PLoS One 2014 12;9(12):e114148. Epub 2014 Dec 12.

Institut de Génomique Fonctionnelle de Lyon, UMR 5242, Université Lyon 1, CNRS, Ecole Normale Supérieure de Lyon, 46 allée d'Italie, 69364 Lyon Cedex 07, France; Plateforme nationale de Paléogénétique PALGENE, CNRS, Ecole Normale Supérieure de Lyon, 46 allée d'Italie, 69364 Lyon Cedex 07, France.

The analysis of ancient or processed DNA samples is often a great challenge, because traditional Polymerase Chain Reaction - based amplification is impeded by DNA damage. Blocking lesions such as abasic sites are known to block the bypass of DNA polymerases, thus stopping primer elongation. In the present work, we applied the SERRS-hybridization assay, a fully non-enzymatic method, to the detection of DNA refractory to PCR amplification. This method combines specific hybridization with detection by Surface Enhanced Resonant Raman Scattering (SERRS). It allows the detection of a series of double-stranded DNA molecules containing a varying number of abasic sites on both strands, when PCR failed to detect the most degraded sequences. Our SERRS approach can quickly detect DNA molecules without any need for DNA repair. This assay could be applied as a pre-requisite analysis prior to enzymatic reparation or amplification. A whole new set of samples, both forensic and archaeological, could then deliver information that was not yet available due to a high degree of DNA damage.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0114148PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4264738PMC
October 2015

Attachment of ribonucleotides on α-alumina as a function of pH, ionic strength, and surface loading.

Langmuir 2015 22;31(1):240-8. Epub 2014 Dec 22.

Geophysical Laboratory, Carnegie Institution of Washington , 5251 Broad Branch Road North West, Washington, DC 20015, United States.

The interactions between nucleic acids and mineral surfaces have been the focus of many studies in environmental sciences, in biomedicine, as well as in origin of life studies for the prebiotic formation of biopolymers. However, few studies have focused on a wide range of environmental conditions and the likely modes of attachment. Here we investigated the adsorption of ribonucleotides onto α-alumina surfaces over a wide range of pH, ionic strength, and ligand-to-solid ratio, by both an experimental and a theoretical approach. The adsorption of ribonucleotides is strongly affected by pH, with a maximum adsorption at pH values around 5. Alumina adsorbs high amounts of nucleotides >2 μmol/m(2). We used the extended triple-layer model (ETLM) to predict the speciation of the surface complexes formed as well as the stoichiometry and equilibrium constants. We propose the formation of two surface species: a monodentate inner-sphere complex, dominant at pH <7, and a bidentate outer-sphere complex, dominant at higher pH. Both complexes would involve interactions between the negatively charged phosphate group and the positively charged surface of alumina. Our results provide a better understanding of how nucleic acids attach to mineral surfaces under varying environmental conditions. Moreover, the predicted configuration of nucleotide surface species, bound via the phosphate group, could have implications for the abiotic formation of nucleic acids in the context of the origin of life.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1021/la504034kDOI Listing
March 2016

Enzyme-free detection and quantification of double-stranded nucleic acids.

Anal Bioanal Chem 2012 Aug 14;404(2):415-22. Epub 2012 Jun 14.

Laboratoire de Géologie de Lyon, Terre, Planètes, Environnement, UMR 5276, Université Lyon 1, CNRS, Ecole Normale Supérieure de Lyon, 46 allée d'Italie, 69364, Lyon Cedex 07, France.

We have developed a fully enzyme-free SERRS hybridization assay for specific detection of double-stranded DNA sequences. Although all DNA detection methods ranging from PCR to high-throughput sequencing rely on enzymes, this method is unique for being totally non-enzymatic. The efficiency of enzymatic processes is affected by alterations, modifications, and/or quality of DNA. For instance, a limitation of most DNA polymerases is their inability to process DNA damaged by blocking lesions. As a result, enzymatic amplification and sequencing of degraded DNA often fail. In this study we succeeded in detecting and quantifying, within a mixture, relative amounts of closely related double-stranded DNA sequences from Rupicapra rupicapra (chamois) and Capra hircus (goat). The non-enzymatic SERRS assay presented here is the corner stone of a promising approach to overcome the failure of DNA polymerase when DNA is too degraded or when the concentration of polymerase inhibitors is too high. It is the first time double-stranded DNA has been detected with a truly non-enzymatic SERRS-based method. This non-enzymatic, inexpensive, rapid assay is therefore a breakthrough in nucleic acid detection.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1007/s00216-012-6133-1DOI Listing
August 2012

A novel SERRS sandwich-hybridization assay to detect specific DNA target.

PLoS One 2011 31;6(5):e17847. Epub 2011 May 31.

Laboratoire de Géologie de Lyon-Terre Planètes Environnement, ENS Lyon, Université Lyon 1, CNRS, Ecole Normale Supérieure de Lyon, Lyon, France.

In this study, we have applied Surface Enhanced Resonance Raman Scattering (SERRS) technology to the specific detection of DNA. We present an innovative SERRS sandwich-hybridization assay that allows specific DNA detection without any enzymatic amplification, such as is the case with Polymerase Chain Reaction (PCR). In some substrates, such as ancient or processed remains, enzymatic amplification fails due to DNA alteration (degradation, chemical modification) or to the presence of inhibitors. Consequently, the development of a non-enzymatic method, allowing specific DNA detection, could avoid long, expensive and inconclusive amplification trials. Here, we report the proof of concept of a SERRS sandwich-hybridization assay that leads to the detection of a specific chamois DNA. This SERRS assay reveals its potential as a non-enzymatic alternative technology to DNA amplification methods (particularly the PCR method) with several applications for species detection. As the amount and type of damage highly depend on the preservation conditions, the present SERRS assay would enlarge the range of samples suitable for DNA analysis and ultimately would provide exciting new opportunities for the investigation of ancient DNA in the fields of evolutionary biology and molecular ecology, and of altered DNA in food frauds detection and forensics.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0017847PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3104981PMC
October 2011
-->