20 results match your criteria: "European Institute of Chemistry and Biology (IECB)[Affiliation]"

Bacterial cellulosic polymers constitute a prevalent class of biofilm matrix exopolysaccharides that are synthesized by several types of bacterial cellulose secretion (Bcs) systems, which include conserved cyclic diguanylate (c-di-GMP)-dependent cellulose synthase modules together with diverse accessory subunits. In E. coli, the biogenesis of phosphoethanolamine (pEtN)-modified cellulose relies on the BcsRQABEFG macrocomplex, encompassing inner-membrane and cytosolic subunits, and an outer membrane porin, BcsC.

View Article and Find Full Text PDF

Protein-protein interactions (PPIs) are central in cell metabolism but research tools for the structural and functional characterization of these PPIs are often missing. Here we introduce broadly applicable immunization (Cross-link PPIs and immunize llamas, ChILL) and selection strategies (Display and co-selection, DisCO) for the discovery of diverse nanobodies that either stabilize or disrupt PPIs in a single experiment. We apply ChILL and DisCO to identify competitive, connective, or fully allosteric nanobodies that inhibit or facilitate the formation of the SOS1•RAS complex and modulate the nucleotide exchange rate on this pivotal GTPase in vitro as well as RAS signalling in cellulo.

View Article and Find Full Text PDF

sp. nov., isolated from the endosphere of a wild yam.

Int J Syst Evol Microbiol

June 2024

Laboratory of Microbiology, Department of Biochemistry and Microbiology, Ghent University, K. L. Ledeganckstraat 35, 9000 Ghent, Belgium.

Article Synopsis
  • A new Gram-negative, strictly aerobic bacterial strain was found in the leaf tissue of a wild yam plant, growing best at 28°C and pH 7.
  • Genetic analysis and comparative genomics showed that this strain, named LMG 33091, is a novel species, closely related to other strains but distinct in its genetic makeup.
  • Additional tests like MALDI-TOF MS confirmed the uniqueness of strain LMG 33091, leading to its classification as a new species, proposed as sp. nov. with LMG 33091 as its type strain.
View Article and Find Full Text PDF

Bacterial synthase-dependent exopolysaccharide secretion: a focus on cellulose.

Curr Opin Microbiol

June 2024

Univ. Bordeaux, CNRS, Bordeaux INP, CBMN, UMR 5248, Pessac F-33600, France; 'Structural Biology of Biofilms' Group, European Institute of Chemistry and Biology (IECB), Pessac F-33600, France. Electronic address:

Bacterial biofilms are a prevalent multicellular life form in which individual members can undergo significant functional differentiation and are typically embedded in a complex extracellular matrix of proteinaceous fimbriae, extracellular DNA, and exopolysaccharides (EPS). Bacteria have evolved at least four major mechanisms for EPS biosynthesis, of which the synthase-dependent systems for bacterial cellulose secretion (Bcs) represent not only key biofilm determinants in a wide array of environmental and host-associated microbes, but also an important model system for the studies of processive glycan polymerization, cyclic diguanylate (c-di-GMP)-dependent synthase regulation, and biotechnological polymer applications. The secreted cellulosic chains can be decorated with additional chemical groups or can pack with various degrees of crystallinity depending on dedicated enzymatic complexes and/or cytoskeletal scaffolds.

View Article and Find Full Text PDF

Structures and roles of BcsD and partner scaffold proteins in proteobacterial cellulose secretion.

Curr Biol

January 2024

Université de Bordeaux, CNRS, Bordeaux INP, CBMN, UMR 5248, Pessac 33600, France; "Structural Biology of Biofilms" Group, European Institute of Chemistry and Biology (IECB), 2 Rue Robert Escarpit, Pessac 33600, France. Electronic address:

Cellulose is the world's most abundant biopolymer, and similar to its role as a cell wall component in plants, it is a prevalent constituent of the extracellular matrix in bacterial biofilms. Although bacterial cellulose (BC) was first described in the 19 century, it was only recently revealed that it is produced by several distinct types of Bcs secretion systems that feature multiple accessory subunits in addition to a catalytic BcsAB synthase tandem. We recently showed that crystalline cellulose secretion in the Gluconacetobacter genus (α-Proteobacteria) is driven by a supramolecular BcsH-BcsD scaffold-the "cortical belt"-which stabilizes the synthase nanoarrays through an unexpected inside-out mechanism for secretion system assembly.

View Article and Find Full Text PDF

Large Complexes: Cloning Strategy, Production, and Purification.

Methods Mol Biol

November 2023

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

With few exceptions-such as myxobacteria, filamentous cyanobacteria, and actinomycetes (Rokas, Annu Rev Genet 42:235-251, 2008)-bacteria are defined as unicellular prokaryotes or single, self-sufficient cells containing all the genetic material necessary for their physiology and reproduction, while maintaining none or a minimum of intracellular organelles for pathway compartmentalization. The latter is therefore primarily achieved through the assembly of macromolecular complexes that can secure spatiotemporal control of a plethora of physiological processes, such as precise midcell division, assembly of diverse motility organelles and chemotaxis sensory arrays, metabolic channeling of substrates and toxic intermediates, localized signal transduction via soluble intracellular second messengers or the secretion of signaling molecules, competition effectors, and extracellular matrix components (Cornejo et al., Curr Opin Cell Biol 26:132-138, 2014; de Lorenzo et al.

View Article and Find Full Text PDF

Cellulose, the most abundant biopolymer on Earth, is not only the predominant constituent of plants but also a key extracellular polysaccharide in the biofilms of many bacterial species. Depending on the producers, chemical modifications, and three-dimensional assemblies, bacterial cellulose (BC) can present diverse degrees of crystallinity. Highly ordered, or crystalline, cellulose presents great economical relevance due to its ever-growing number of biotechnological applications.

View Article and Find Full Text PDF

The combination of NiX salts with a bipyridine-type ligand and aromatic carbonyl-based chromophores has emerged as a benchmark precatalytic system to efficiently conduct cross-couplings mediated by light. Mechanistic studies have led to two scenarios in which Ni is proposed as the catalytic species. Nonetheless, in none of these studies has a Ni to Ni photoreduction been evidenced.

View Article and Find Full Text PDF

In rod-shaped bacteria, the emergence and maintenance of long-axis cell polarity is involved in key cellular processes such as cell cycle, division, environmental sensing and flagellar motility among others. Many bacteria achieve cell pole differentiation through the use of polar landmark proteins acting as scaffolds for the recruitment of functional macromolecular assemblies. In Vibrio cholerae a large membrane-tethered protein, HubP, specifically interacts with proteins involved in chromosome segregation, chemotaxis and flagellar biosynthesis.

View Article and Find Full Text PDF

Cellulose is the most abundant biological compound on Earth and while it is the predominant building constituent of plants, it is also a key extracellular matrix component in many diverse bacterial species. While bacterial cellulose was first described in the 19th century, it was not until this last decade that a string of structural works provided insights into how the cellulose synthase BcsA, assisted by its inner-membrane partner BcsB, senses c-di-GMP to simultaneously polymerize its substrate and extrude the nascent polysaccharide across the inner bacterial membrane. It is now established that bacterial cellulose can be produced by several distinct types of cellulose secretion systems and that in addition to BcsAB, they can feature multiple accessory subunits, often indispensable for polysaccharide production.

View Article and Find Full Text PDF

The plasma membrane is a key actor of cell migration. For instance, its tension controls persistent cell migration and cell surface caveolae integrity. Then, caveolae constituents such as caveolin-1 can initiate a mechanotransduction loop that involves actin- and focal adhesion-dependent control of the mechanosensor YAP to finely tune cell migration.

View Article and Find Full Text PDF

Architecture and regulation of an enterobacterial cellulose secretion system.

Sci Adv

January 2021

Institute for Integrative Biology of the Cell (I2BC), CEA, CNRS, Université Paris-Sud, 91198 Gif- sur-Yvette, France.

Many free-living and pathogenic enterobacteria secrete biofilm-promoting cellulose using a multicomponent, envelope-embedded Bcs secretion system under the control of intracellular second messenger c-di-GMP. The molecular understanding of system assembly and cellulose secretion has been largely limited to the crystallographic studies of a distantly homologous BcsAB synthase tandem and a low-resolution reconstruction of an assembled macrocomplex that encompasses most of the inner membrane and cytosolic subunits and features an atypical layered architecture. Here, we present cryo-EM structures of the assembled Bcs macrocomplex, as well as multiple crystallographic snapshots of regulatory Bcs subcomplexes.

View Article and Find Full Text PDF

Structure and Multitasking of the c-di-GMP-Sensing Cellulose Secretion Regulator BcsE.

mBio

August 2020

Structural Biology of Biofilms Group, Institute for Integrative Biology of the Cell (I2BC), CEA, CNRS, Paris-Sud University, Gif-sur-Yvette, France

Most bacteria respond to surfaces by biogenesis of intracellular c-di-GMP, which inhibits motility and induces secretion of biofilm-promoting adherence factors. Bacterial cellulose is a widespread biofilm component whose secretion in Gram-negative species requires an inner membrane, c-di-GMP-dependent synthase tandem (BcsAB), an outer membrane porin (BcsC), and various accessory subunits that regulate synthase assembly and function as well as the exopolysaccharide's chemical composition and mechanical properties. We recently showed that in , most Bcs proteins form a megadalton-sized secretory nanomachine, but the role and structure of individual regulatory components remained enigmatic.

View Article and Find Full Text PDF

Structure of two G-quadruplexes in equilibrium in the KRAS promoter.

Nucleic Acids Res

September 2020

European Institute of Chemistry and Biology (IECB), ARNA laboratory, INSERM U1212 - CNRS UMR 5320, University of Bordeaux, France.

KRAS is one of the most mutated oncogenes and still considered an undruggable target. An alternative strategy would consist in targeting its gene rather than the protein, specifically the formation of G-quadruplexes (G4) in its promoter. G4 are secondary structures implicated in biological processes, which can be formed among G-rich DNA (or RNA) sequences.

View Article and Find Full Text PDF

Selectivities in (4 + 2) and (2 + 2) cycloadditions of keteniminium cations with 1,3-dienes studied experimentally by Ghosez et al. were explored with ωB97X-D density functional theory. Reactions of keteniminium cations with 1,3-dienes are influenced by the -cis or -trans nature of the diene.

View Article and Find Full Text PDF

The photosensitized -anisaldehyde-mediated addition of sulfonylcyanides onto the π-system of cyclobutenes is shown to afford highly functionalized cyclobutanes in high yields and diastereocontrol. The homochiral cyclobutene precursors are accessible on multigram scale in two steps through an asymmetric [2 + 2] cycloaddition/vinyl thioether reduction sequence. The enantiopure cyclobutylnitriles can be elaborated further through SmI-mediated ring opening or converted into new enantiopure cyclobutenes through base-mediated sulfone elimination.

View Article and Find Full Text PDF

Progress in Antiparasitic Drug Discovery: From the Laboratory Bench to the Collaborative Initiatives.

Curr Top Med Chem

March 2019

ARNA unit "RNA: Natural and Artificial Regulation", University of Bordeaux / INSERM U1212 / CNRS UMR5320, European Institute of Chemistry and Biology (IECB), 2, Rue Robert Escarpit, 33607, Pessac, France.

View Article and Find Full Text PDF

Pure diastereomeric spirocyclic analogs of fluorocortivazol were conveniently prepared by a short and efficient synthetic sequence recently developed in our laboratory. The structures and conformations of several key products were confirmed by single crystal X-ray diffraction analysis. Conformational assignments were also supported by DFT calculations.

View Article and Find Full Text PDF

A general access to the spiroimine skeleton of gymnodimine and spirolides is described, relying on the construction of the cyclohexene fragment using an enantiocontrolled Diels-Alder reaction, the installation of the all-carbon quaternary stereocenter through a stereocontrolled alkylation or aldolisation and the elaboration of the lateral chains at C7 and C22 using Wittig-Horner olefinations. The spiroimine core of gymnodimine is made available through a 16-step linear sequence in a 21 % overall yield.

View Article and Find Full Text PDF

H, C, and N chemical shift assignments of a G-quadruplex forming sequence within the KRAS proto-oncogene promoter region.

Biomol NMR Assign

April 2018

ARNA Laboratory, European Institute of Chemistry and Biology (IECB), Université de Bordeaux, Inserm U1212 - CNRS UMR 5320, 2, rue Robert Escarpit, 33607, Pessac, France.

Single stranded guanine rich DNA (or RNA) sequences adopt noncanonical secondary structures called G-quadruplexes (G4). Functionally, quadruplexes control gene transcription and regulate activities such as replication, gene recombination or alternative splicing. Hence they are potential targets for cancer, neuronal, and viral related diseases.

View Article and Find Full Text PDF