A5006689829- Lipid Membrane Structure and Behavior
- Ion channel regulation and function
- Bacterial Genetics and Biotechnology
- Nanopore and Nanochannel Transport Studies
- Erythrocyte Function and Pathophysiology
- DNA and Nucleic Acid Chemistry
- RNA and protein synthesis mechanisms
- Amino Acid Enzymes and Metabolism
- Mitochondrial Function and Pathology
- Neuroscience and Neuropharmacology Research
- Prion Diseases and Protein Misfolding
- Protein Structure and Dynamics
- Cellular and Composite Structures
- Enzyme Structure and Function
- Antimicrobial Peptides and Activities
- Cancer-related Molecular Pathways
- Connexins and lens biology
- Theoretical and Computational Physics
- Polymer composites and self-healing
- Supramolecular Chemistry and Complexes
- Biochemical and Structural Characterization
- RNA Interference and Gene Delivery
- Bacteriophages and microbial interactions
- Glycosylation and Glycoproteins Research
- Plant-Microbe Interactions and Immunity
Centre de Recherche des Cordeliers
2019-2022
Université Paris Cité
1981-2021
Sorbonne Université
2019-2021
Inserm
2021
University of Lisbon
2019-2020
Université Libre de Bruxelles
2019-2020
Sorbonne Paris Cité
2019
Université Paris-Sud
1998-2015
Centre National de la Recherche Scientifique
1999-2015
Université Djilali de Sidi Bel Abbès
2010
Insect defensins are cationic, cysteine-rich peptides (approximately 4 kDa) that appear after bacterial challenge or injury in the hemolymph of insects belonging to a large variety orders. These possess anti-Gram-positive activity and participate potent antibacterial defense reactions insects. Using recombinant insect defensin strain Micrococcus luteus as test organism, we have investigated mode action this peptide. We show disrupts permeability barrier cytoplasmic membrane M. luteus,...
Treatment of hyphae Neurospora crassa with antifungal plant defensins, i.e. Rs-AFP2 and Dm-AMP1 isolated from radish dahlia seed, respectively, induced a rapid K+ efflux, Ca2+ uptake, alkalinization the incubation medium. The Rs-AFP2-induced medium could be inhibited G-protein inhibitors. α-Hordothionin, an thionin barley caused sustained increased uptake at subinhibitory concentrations but only transient inhibitory concentrations. α-Hordothionin also efflux medium, these fluxes occurred...
Bacteria subjected to a hypotonic osmotic shock lose internal ions and also metabolites, without lysis of the cells. We show that presence in medium, at submillimolar concentrations, ion gadolinium, recently shown block stretch-activated channels Xenopus oocytes [Yang, X.-C. & Sachs, F. (1989) Science 243, 1068-1071], was sufficient inhibit shock-induced release metabolites such as lactose ATP Escherichia coli Streptococcus faecalis. Moreover, gadolinium observed, patch-clamp experiments,...
The outer membrane protein PulD (secretin) of Klebsiella oxytoca is required for transport pullulanase across this membrane. We have purified a multimeric complex from an Escherichia coli strain expressing all the proteins involved in secretion. membrane-anchored lipoprotein PulS was found to copurify with PulD. molar ratio two close 1:1, and size ≈1 MDa. Scanning transmission electron cryo-electron microscopy analyses showed that cylindrical structure having central cavity ≈7.6 nm...
Glycine betaine is mostly known as an osmoprotectant. It involved in the osmotic adaptation of eukaryotic and bacterial cells, accumulates up to 1 M inside cells subjected upshock. Since, like other osmolytes, it can act a protein stabilizer, its thermoprotectant properties were investigated. In vitro, chaperones such DnaK, glycine choline protect citrate synthase against thermodenaturation, stimulate renaturation after urea denaturation. vivo, internal concentration neither increased nor...
Escherichia coli cells possess several mechanosensitive ion channels but only MscL, the channel with highest conductance, which is activated at membrane tension, has been cloned. We investigated putative involvement of MscL in effluxes caused by osmotic downshock. Osmotic shock release potassium glutamate, trehalose, and glycine betaine from wild type lacking MscL. There was no difference between two strains, extreme rapidity efflux process, as shown herein for betaine, suggests that it...
Inner and outer membranes of Escherichia coli contact zones were isolated fused separately with giant liposomes amenable to patch-clamp recording. Different types large pressure-activated channels localized in the inner membrane fraction which also contained smaller, pressure-insensitive channels. The conductances long opening closing times are likely be porins. Large observed zones.
Mechanosensitive channels are detected in all cells and speculated to play a key role many functions including osmoregulation, growth, hearing, balance, touch. In prokaryotic cells, direct gating of mechanosensitive by membrane tension was clearly demonstrated because the purified could be functionally reconstituted lipid bilayer. No such evidence has been presented yet case from animal cells. TREK-1, two-pore domain K(+) channel, first channel identified at molecular level. It is target...
Bid is a proapoptotic, BH3-domain-only member of the Bcl-2 family. In Fas-induced apoptosis, activated through cleavage by caspase 8 into 15.5-kDa C-terminal fragment (t<sup>c</sup>Bid) and 6.5 kDa N-terminal (t<sup>n</sup>Bid). Following cleavage, t<sup>c</sup>Bid translocates to mitochondria promotes release cytochrome<i>c</i> cytosol mechanism that not understood. Here we report recombinant can act as membrane destabilizing agent. induces destabilization breaking planar lipid bilayers...
We have investigated the possibility of cell-fee synthesis membrane proteins in absence a and presence detergent. used bacterial mechanosensitive channel MscL, homopentamer, as model protein. A wide range nonionic or zwitterionic detergents, Triton X-100, Tween 20, Brij 58p, n-dodecyl β-d-maltoside, CHAPS, were compatible with cell-free synthesis, while n-octyl β-d-glucoside deoxycholate had an inhibitory effect. In vitro X-100 yielded milligram amounts MscL per milliliter lysate....
MscL is a mechanosensitive channel that gated by tension in the membrane bilayer alone. It homo-oligomer of protein comprising two transmembrane segments connected an external loop, with NH<sub>2</sub> and COOH termini located cytoplasm. The contributions extramembranous domains to its activity were investigated specific proteolysis during patch-clamp experiments. Limited terminus or increased mechanosensitivity without changing conductance. Strikingly, after cleavage loop each monomer, was...
ABSTRACT Upon osmotic downshock, a few cytoplasmic proteins, including thioredoxin, elongation factor Tu (EF-Tu), and DnaK, are released from Tris-EDTA-treated Escherichia coli cells by an unknown mechanism. We have shown previously that deletion of mscL , the gene coding for mechanosensitive channel plasma membrane with highest conductance, prevents release thioredoxin. confirm extend implication MscL in this process showing EF-Tu DnaK is severely impaired MscL-deficient strains. Release...
Hemifluorinated and fluorinated surfactants are lipophobic and, as such, non-detergent. Although they do not solubilize biological membranes, can, after conventional solubilization, substitute for detergents to keep membrane proteins soluble, which generally improves their stability [Breyton, Chabaud, Chaudier, Pucci Popot (2004) FEBS Lett. 564, 312–318]. In the present study, we show that (hemi)fluorinated can be used in vitro synthesis of proteins: interfere with protein synthesis, provide...
Mechanosensitive (MS) ion channels have been documented in a variety of cells belonging to <i>Eukarya</i> and<i>Eubacteria</i>. We report the novel finding two types MS cell membrane halophilic archaeon<i>Haloferax volcanii</i>, member <i>Archaea</i>that comprise third phylogenetic domain. The channels, MscA1 and MscA2, differed their kinetic properties with exhibiting more frequent open-closed transitions than MscA2. Both large conductances that rectify between −40 mV +40 where conductance...
The transport of genetic material across biomembranes is a process great relevance for several fields study. However, much remains to be learned about the mechanisms underlying transport, one which implies involvement proteic DNA-conducting pores. Entry into mitochondria has been observed under both physiological and pathological conditions. We report here that double-stranded DNA can move through planar bilayer membrane containing isolated mitochondrial porin (voltage-dependent anion...
ABSTRACT The Escherichia coli yjhA (renamed nanC) gene encodes a protein of the KdgM family outer membrane-specific channels. It is transcribed divergently from fimB , involved in site-specific inversion region controlling transcription fimbrial structural genes but separated it by one largest intergenic regions E. . We show that nanC expression induced N -acetylneuraminic acid and modulated -acetylglucosamine. This regulation occurs via NanR NagC regulators, which also control expression....
The separation of proteins by gel-exclusion chromatography has been explained in terms partitioning the macromolecules within gel a distribution pores various radii. assumption that pore sizes is Gaussian led to prediction linear relationship between molecular Stokes radius (RS) protein and function erf-1 (1-KD), where KD partition coefficient [Ackers (1967) J. Biol. Chem. 242, 3237-3238]. Since careful calibrations classical (agarose dextran) gels h.p.l.c. have shown such not verified...
O-acylation of proteins was known only in a few eukaryotic but never bacteria. We demonstrate, using combination protein chemistry and mass spectrometry, the occurrence three O-acylated polypeptides Corynebacterium glutamicum, PorA, PorH, an unknown small protein. The are O-substituted by mycolic acids, long chain alpha-alkyl beta-hydroxy fatty acids specifically produced members Corynebacterineae suborder. To date these were described as esterifying trehalose arabinogalactan, less...
Comprehensive transcriptomic analyses have shown that colorectal cancer (CRC) is heterogeneous and led to the definition of molecular subtypes among which stem-cell, mesenchymal-like group associated with poor prognosis. The pathways orchestrating emergence this subtype are incompletely understood. In line contribution cellular prion protein PrPC stemness, we hypothesize deregulation could lead a phenotype in CRC. We assessed distribution PrPC-encoding PRNP mRNA two large CRC cohorts...
This study presents an imaged-based shell modelling strategy for closed cell metallic foams exploiting X-ray Computed Tomography scans, with its illustration on ALCORAS® foams. Based in situ CT compression test, the 3D segmentation is complemented by a watershed method and geodesic reconstruction technique to isolate cells identify missing walls. An implicit geometry reconstructed each based distance field computation technique. automated procedure extracts from this geometry, followed...
The phytopathogenic Gram-negative bacteria <i>Erwinia chrysanthemi</i> secretes pectinases, which are able to degrade the pectic polymers of plant cell walls, and uses degradation products as a carbon source for growth. We characterized major outer membrane protein, KdgM, whose synthesis is strongly induced in presence derivatives. corresponding gene was characterized. Analysis transcriptional fusions showed that <i>kdgM</i> expression controlled by general repressor pectinolytic genes,...