Florence Vincent

French National Centre for Scientific Research | CNRS · Laboratoire AFMB, UMR7257

Virulence in Pseudomonas aeruginosa (PA) depends on complex regulatory networks, involving phosphorelay systems based on two-component systems (TCSs). The GacS/GacA TCS is a master regulator of biofilm formation, swarming motility, and virulence. GacS is a membrane-associated unorthodox histidine kinase (HK) whose phosphorelay signaling pathway is...

The cleavage of septal peptidoglycan at the end of cell division facilitates the separation of the two daughter cells. The hydrolases involved in this process (called autolysins) are potentially lethal enzymes that can cause cell death; their activity, therefore, must be tightly controlled during cell growth. In Enterococcus faecalis, the N-acetylg...

Glycosyltransferases (GTs) are widely present in several organisms. These enzymes specifically transfer sugar moieties to a range of substrates. The processes of bacterial glycosylation of the cell wall and their relations with host–pathogen interactions have been studied extensively, yet the majority of mycobacterial GTs involved in the cell wall...

CAZypedia was initiated in 2007 to create a comprehensive, living encyclopedia of the carbohydrate active enzymes (CAZymes) and associated carbohydrate-binding modules involved in the synthesis, modification and degradation of complex carbohydrates. CAZypedia is closely connected with the actively curated CAZy database, which provides a sequence-ba...

Pseudomonas aeruginosa is an opportunistic pathogenic bacterium responsible for both acute and chronic infections and has developed resistance mechanisms due to its ability to promote biofilm formation and evade host adaptive immune responses. Here, we investigate the functional role of the periplasmic detector domain (GacSPD) from the membrane-bou...

Pseudomonas aeruginosa is a highly adaptable opportunistic pathogen. It can infect vulnerable patients such as those with cystic fibrosis or hospitalized in intensive care units where it is responsible for both acute and chronic infection. The switch between these infections is controlled by a complex regulatory system involving the central GacS/Ga...

Bacteria from the human gut are equipped with an arsenal of carbohydrate-active enzymes that degrade dietary and host-derived glycans. In this study, we present the 2.5Å resolution crystal structure of a member (GH39wh2) from the human gut bacteria Bacteroides cellulosilyticus WH2 representative of a new subgroup within family GH39. Together with 6...

In this study, the recombinant α-l-arabinofuranosidase from the fungus Pleurotus ostreatus (rPoAbf) was subjected to site-directed mutagenesis in order to identify the catalytic nucleophile residue. Based on bioinformatics and homology modelling analyses, E449 was revealed to be the potential nucleophilic residue. Thus, the mutant E449G of PoAbf wa...

Members of the GH73 glycosidase family cleave the β-1,4-glycosidic bond between the N-acetylglucosaminyl (GlcNAc) and N-acetylmuramyl (MurNAc) moieties in bacterial peptidoglycan. A catalytic mechanism has been proposed for members FlgJ, Auto, AcmA and Atl(WM) and the structural analysis of FlgJ and Auto revealed a conserved α/β fold reminiscent of...

Pathogenic bacteria are endowed with an arsenal of specialized enzymes to convert nutrient compounds from their cell hosts. The essential N-acetylmannosamine-6-phosphate 2-epimerase (NanE) belongs to a convergent glycolytic pathway for utilization of the three amino sugars, GlcNAc, ManNAc and sialic acid. The crystal structure of ligand-free NanE f...

In this study, the α-L-arabinofuranosidase from Pleurotus ostreatus was subjected to directed evolution by expressing a library of around 7000 randomly mutated variants by error prone Polymerase Chain Reaction. High-throughput screening of the library for the most active variants was performed by assaying activity towards p-nitrophenyl α- L-arabino...

Bacterial enzymatic degradation of glycosaminoglycans such as hyaluronan and chondroitin is facilitated by polysaccharide lyases. Family 8 polysaccharide lyase (PL8) enzymes contain at least two domains: one predominantly composed of α-helices, the α-domain, and another predominantly composed of β-sheets, the β-domain. Simulation flexibility analys...

Bacterial two-component regulatory systems (TCSs) sense environmental stimuli to adapt the lifestyle of microbial populations. For many TCSs the stimulus is a ligand of unknown chemical nature. Pseudomonas aeruginosa utilizes the closely related RetS and LadS sensor kinases to switch between acute and chronic infections. These sensor proteins antag...

Saccharophagus degradans belongs to a recently discovered group of marine bacteria equipped with an arsenal of sugar cleaving enzymes coupled to carbohydrate-binding domains to degrade various insoluble complex polysaccharides. The modular Sde-1182 protein consists of a family 2 carbohydrate binding module linked to a X158 domain of unknown functio...

The enzymatic degradation of plant cell wall xylan requires the concerted action of a diverse enzymatic syndicate. Among these enzymes are xylan esterases, which hydrolyze the O-acetyl substituents, primarily at the O-2 position of the xylan backbone. All acetylxylan esterase structures described previously display a alpha/beta hydrolase fold with...

Glucosamine 6-phosphate is converted to fructose 6-phosphate and ammonia by the action of the enzyme glucosamine 6-phosphate deaminase, NagB. This reaction is the final step in the specific GlcNAc utilization pathway and thus decides the metabolic fate of GlcNAc. Sequence analyses suggest that the NagB "superfamily" consists of three main clusters:...

Glucosamine 6-phosphate is converted to fructose 6-phosphate and ammonia by the action of the enzyme glucosamine 6-phosphate deaminase, NagB. This reaction is the final step in the specific GlcNAc utilization pathway and thus decides the metabolic fate of GlcNAc. Sequence analyses suggest that the NagB "superfamily" consists of three main clusters:...

Metal ions such as calcium often play a key role in protein thermostability. The inclusion of metal ions in industrial processes is, however, problematic. Thus, the evolution of enzymes that display enhanced stability, which is not reliant on divalent metals, is an important biotechnological goal. Here we have used forced protein evolution to inter...

Glycosidase inhibition is a key process both in the pursuit of new therapeutic agents and in the drive to understand transition-state stabilisation by these remarkable enzymes. That isofagomine lactam (1) is an equally potent inhibitor of β-glucosidases and β-mannosidases (despite possessing a carbonyl group) adds to the emerging view that mannosid...

The structure of bovine odorant-binding protein (bOBP) revealed a striking feature of a dimer formed by domain swapping [Tegoni, M., Ramoni, R., Bignetti, E., Spinelli, S. & Cambillau, C. (1996) Nat. Struct. Biol.3, 863-867; Bianchet, M.A., Bains, G., Pelosi, P., Pevsner, J., Snyder, S.H., Monaco, H.L. & Amzel, L.M. (1996) Nat. Struct. Biol.3, 934-...

The enzymatic hydrolysis of the glycosidic bond is central to numerous biological processes. Glycoside hydrolases, which catalyze these reactions, are grouped into families based on primary sequence similarities. One of the largest glycoside hydrolase families is glycoside hydrolase family 5 (GH5), which contains primarily endo-acting enzymes that...

The enzyme N-acetylglucosamine-6-phosphate deacetylase, NagA, catalyzes the hydrolysis of the N-acetyl group of GlcNAc-6-P to yield glucosamine 6-phosphate and acetate, the first committed step in the biosynthetic pathway to amino-sugar-nucleotides. It is classified into carbohydrate esterase family CE-9 (see afmb.cnrs-mrs.fr/CAZY/). Here we report...

Esterases and deacetylases active on carbohydrate ligands have been classified into 14 families based upon amino acid sequence similarities. Enzymes from carbohydrate esterase family seven (CE-7) are unusual in that they display activity towards both acetylated xylooligosaccharides and the antibiotic, cephalosporin C. The 1.9A structure of the mult...

As revealed by the X-ray structure, bovine odorant-binding protein (OBPb) is a domain swapped dimer [Tegoni, Ramoni, Bignetti, Spinelli and Cambillau (1996) Nat. Struct. Biol. 3, 863-867; Bianchet, Bains, Petosi, Pevsner, Snyder, Monaco and Amzel (1996) Nat. Struct. Biol. 3, 934-939]. This contrasts with all known mammalian OBPs, which are monomers...

The X-ray structure of variant A of authentic boar salivary lipocalin (SAL), a pheromone-binding protein specifically expressed in the submaxillary glands of the boar, has been solved and refined at 2.1 A resolution. The structure displays a classical lipocalin fold with a nine-stranded sandwiched beta barrel and an alpha helix. A putative glycosyl...

Bovine odorant-binding protein (bOBP) is a dimeric lipocalin present in large amounts in the respiratory and olfactory nasal mucosa. The structure of bOBP refined at 2.0-A resolution revealed an elongated volume of electron density inside each buried cavity, indicating the presence of one (or several) naturally occurring copurified ligand(s) (Tegon...

We have solved the crystal structure of aphrodisin, a pheromonal protein inducing a copulatory behaviour in male hamster, using MAD methods with selenium, at 1.63 Å resolution. The monomeric protein belongs to the lipocalin family, and possesses a disulfide bridge in a loop between strands 2 and 3. This disulfide bridge is characteristic of a famil...

Odorant binding proteins (OBPs) pertain to one of the most abundant classes of proteins found in the olfactory apparatus. OBPs are a sub-class of lipocalins, defined by their property of reversibly binding volatile chemicals, that we call ‘odorants’. Numerous sequences of OBPs are now available, derived from protein sequencing from nasal mucus mate...

Porcine odorant binding protein (pOBP) is a monomer of 157 amino acid residues, purified in abundance from pig nasal mucosa. In contrast to the observation on lipocalins as retinol binding protein (RBP), major urinary protein (MUP) or bovine odorant binding protein (bOBP), no naturally occurring ligand was found in the β-barrel cavity of pOBP. Porc...

Transcriptional antiterminators of the BglG/SacY family are regulatory proteins that mediate the induction of sugar metabolizing operons in Gram-positive and Gram-negative bacteria. Upon activation, these proteins bind to specific targets in nascent mRNAs, thereby preventing abortive dissociation of the RNA polymerase from the DNA template. We have...