Publications by authors named "Nathalie Dautin"

LppX is an important virulence factor essential for surface localization of phthiocerol dimycocerosates (DIM) in Mycobacterium tuberculosis. Based on Concanavalin A recognition, M. tuberculosis LppX (LppX-tb) was initially proposed to be glycosylated in M.

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The type 5 secretion system (T5SS) is one of the more widespread secretion systems in Gram-negative bacteria. Proteins secreted by the T5SS are functionally diverse (toxins, adhesins, enzymes) and include numerous virulence factors. Mechanistically, the T5SS has long been considered the simplest of secretion systems, due to the paucity of proteins required for its functioning.

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Membrane remodeling and phospholipid biosynthesis are normally tightly regulated to maintain the shape and function of cells. Indeed, different physiological mechanisms ensure a precise coordination between de novo phospholipid biosynthesis and modulation of membrane morphology. Interestingly, the overproduction of certain membrane proteins hijack these regulation networks, leading to the formation of impressive intracellular membrane structures in both prokaryotic and eukaryotic cells.

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Bacterial lipoproteins are secreted proteins that are post-translationally lipidated. Following synthesis, preprolipoproteins are transported through the cytoplasmic membrane via the Sec or Tat translocon. As they exit the transport machinery, they are recognized by a phosphatidylglycerol::prolipoprotein diacylglyceryl transferase (Lgt), which converts them to prolipoproteins by adding a diacylglyceryl group to the sulfhydryl side chain of the invariant Cys residue.

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The genomes of Corynebacteriales contain several genes encoding mycoloyltransferases (Myt) that are specific cell envelope enzymes essential for the biogenesis of the outer membrane. MytA is a major mycoloyltransferase of Corynebacterium glutamicum, displaying an N-terminal domain with esterase activity and a C-terminal extension containing a conserved repeated Leu-Gly-Phe-Pro (LGFP) sequence motif of unknown function. This motif is highly conserved in Corynebacteriales and found associated with cell wall hydrolases and with proteins of unknown function.

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Protein mycoloylation is a recently identified, new form of protein acylation. This post-translational modification consists in the covalent attachment of mycolic acids residues to serine. Mycolic acids are long chain, α-branched, β-hydroxylated fatty acids that are exclusively found in the cell envelope of Corynebacteriales, a bacterial order that includes important genera such as Mycobacterium, Nocardia or Corynebacterium.

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Mycobacterium and Corynebacterium are important genera of the Corynebacteriales order, the members of which are characterized by an atypical diderm cell envelope. Indeed the cytoplasmic membrane of these bacteria is surrounded by a thick mycolic acid-arabinogalactan-peptidoglycan (mAGP) covalent polymer. The mycolic acid-containing part of this complex associates with other lipids (mainly trehalose monomycolate (TMM) and trehalose dimycolate (TDM)) to form an outer membrane.

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Intimins and invasins are virulence factors produced by pathogenic Gram-negative bacteria. They contain C-terminal extracellular passenger domains that are involved in adhesion to host cells and N-terminal β domains that are embedded in the outer membrane. Here, we identify the domain boundaries of an E.

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Autotransporters are secreted proteins produced by pathogenic Gram-negative bacteria. They consist of a membrane-embedded β-domain and an extracellular passenger domain that is sometimes cleaved and released from the cell surface. We solved the structures of three noncleavable mutants of the autotransporter EspP to examine how it promotes asparagine cyclization to cleave its passenger.

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Autotransporters are a superfamily of virulence factors produced by Gram-negative bacteria that are comprised of an N-terminal extracellular domain (passenger domain) and a C-terminal β barrel domain (β domain) that resides in the outer membrane (OM). The β domain promotes the translocation of the passenger domain across the OM by an unknown mechanism. Available evidence indicates that an α-helical segment that spans the passenger domain-β domain junction is embedded inside the β domain at an early stage of assembly.

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Autotransporters are bacterial virulence factors consisting of an N-terminal "passenger domain" that is secreted in a C- to-N-terminal direction and a C-terminal "β domain" that resides in the outer membrane (OM). Although passenger domain secretion does not appear to use ATP, the energy source for this reaction is unknown. Here, we show that efficient secretion of the passenger domain of the Escherichia coli O157:H7 autotransporter EspP requires the stable folding of a C-terminal ≈17-kDa passenger domain segment.

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Serine Protease Autotransporters of Enterobacteriaceae (SPATEs) constitute a large family of proteases secreted by Escherichia coli and Shigella. SPATEs exhibit two distinct proteolytic activities. First, a C-terminal catalytic site triggers an intra-molecular cleavage that releases the N-terminal portion of these proteins in the extracellular medium.

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Autotransporters are virulence factors produced by Gram-negative bacteria. They consist of two domains, an N-terminal 'passenger' domain and a C-terminal beta-domain. beta-domains form beta-barrel structures in the outer membrane while passenger domains are translocated into the extracellular space.

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Autotransporters are a large and diverse superfamily of proteins produced by pathogenic gram-negative bacteria that are composed of an N-terminal passenger domain, which typically harbors a virulence function, and a C-terminal beta domain. It has long been known that the beta domain anchors the protein to the outer membrane and facilitates transport of the passenger domain into the extracellular space. Despite the apparent simplicity of the autotransporter pathway, several aspects of autotransporter biogenesis remain poorly understood, most notably the mechanism by which the passenger domain is translocated across the outer membrane.

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Bacterial autotransporters are comprised of an N-terminal 'passenger domain' and a C-terminal beta barrel ('beta domain') that facilitates transport of the passenger domain across the outer membrane. Following translocation, the passenger domains of some autotransporters are cleaved by an unknown mechanism. Here we show that the passenger domain of the Escherichia coli O157:H7 autotransporter EspP is released in a novel autoproteolytic reaction.

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Formation of the Escherichia coli division septum is catalyzed by a number of essential proteins (named Fts) that assemble into a ring-like structure at the future division site. Several of these Fts proteins are intrinsic transmembrane proteins whose functions are largely unknown. Although these proteins appear to be recruited to the division site in a hierarchical order, the molecular interactions underlying the assembly of the cell division machinery remain mostly unspecified.

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Bordetella pertussis, the causative agent of whooping cough, secretes among other virulence factors an adenylate cyclase (AC) toxin that is able to enter into eukaryotic cells where it is activated upon binding to endogenous calmodulin (CaM) and synthesizes supraphysiological cAMP levels. In vivo, the AC toxin, through its specific interaction with the CD11b/CD18 integrin, primarily targets phagocytic cells such as neutrophils and macrophages. Because neutrophil priming and activation result in the production of reactive oxygen species that may cause intracellular oxidation, we have examined the biological consequences of the oxidation of CaM methionines upon its interaction with AC.

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The protease (PR) from human immunodeficiency virus (HIV) is essential for viral replication: this aspartyl protease, active only as a dimer, is responsible for cleavage of the viral polyprotein precursors (Gag and Gag-Pol), to release the functional mature proteins. In this work, we have studied the structure-function relationships of the HIV PR by combining a genetic test to detect proteolytic activity in Escherichia coli and a bacterial two-hybrid assay to analyze PR dimerization. We showed that a drug-resistant PR variant isolated from a patient receiving highly active antiretroviral therapy is impaired in its dimerization capability and, as a consequence, is proteolytically inactive.

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