Structural basis of calcium and galactose recognition by the lectin PA-IL ofPseudomonas aeruginosa (original) (raw)
Related papers
FEBS Letters, 2006
The lectin from Pseudomonas aeruginosa (PA-IIL) is involved in host recognition and biofilm formation. Lectin not only displays an unusually high affinity for fucose but also binds to L L-fucose, L L-galactose and D D-arabinose that differ only by the group at position 5 of the sugar ring. Isothermal calorimetry experiments provided precise determination of affinity for the three methyl-glycosides and revealed a large enthalpy contribution. The crystal structures of the complexes of PA-IIL with L L-galactose and Met-b-D D-arabinoside have been determined and compared with the PA-IIL/fucose complex described previously. A combination of the structures and thermodynamics provided clues for the role of the hydrophobic group in affinity.
ChemistrySelect, 2017
Due to the ability of Pseudomonas aeruginosa (PA) to develop antibiotic resistances, alternative therapeutic strategies have been proposed. Among others, carbohydrate multivalent molecules targeting lectin-based virulent factors have been widely reported in particular those targeting LecA. LecA is a tetravalent galactose specific lectin involved in biofilm formation and cell internalization. Herein, we report the synthesis of 36 galactoclusters built from galactosides with aromatic and non-aromatic aglycons and with an additional chain. The chains were either neutral or positively charged. Only the galactoclusters with naphthyl or tyrosine aglycon showed a moderate increase of binding for the positively charged 3-dimethylammonium propyl chain. In contrast, the non-aromatic galactoclusters display typically poorer binding properties towards LecA. The introduction of these side chains led to improved affinities up to becoming comparable to the high-affinity aromatic galactoclusters.
Biochemical Journal, 2005
One of the mechanisms contributing to the protection by breastfeeding of the newborn against enteric diseases is related to the ability of human milk oligosaccharides to prevent the attachment of pathogenic bacteria to the duodenual epithelium. Indeed, a variety of fucosylated oligosaccharides, specific to human milk, form part of the innate immune system. In the present study, we demonstrate the specific blocking of PA-IIL, a fucose-binding lectin of the human pathogen Pseudomonas aeruginosa, by milk oligosaccharides. Two fucosylated epitopes, Lewis a and 3-fucosyl-lactose (Lewis x glucose analogue) bind to the lectin with dissociation constants of 2.2 × 10 −7 M and 3.6 × 10 −7 M respectively. Thermodynamic studies indicate that these interactions are dominated by enthalpy. The entropy contribution is slightly favourable when binding to fucose and to the highest-affinity ligand, Lewis a. The high-resolution X-ray structures of two complexes of PA-IIL with milk oligosaccharides allow the precise determination of the conformation of a trisaccharide and a pentasaccharide. The different types of interaction between the oligosaccharides and the protein involve not only hydrogen bonding, but also calcium-and waterbridged contacts, allowing a rationalization of the thermodynamic data. This study provides important structural information about compounds that could be of general application in new therapeutic strategies against bacterial infections.
Journal of Biological Chemistry, 2010
The calcium-dependent lectin I from Pseudomonas aeruginosa (PA-IL) binds specifically to oligosaccharides presenting an -galactose residue at their non-reducing end, such as the disaccharides Gal1-2GalOMe, Gal1-3GalOMe and Gal1-4GalOMe. This provides a unique model for studying the effect of the glycosidic linkage of the ligands on structure and thermodynamics of the complexes by means of experimental and theoretical tools. The structural features of PA-IL in complex with the three disaccharides were established by docking and molecular dynamics (MD) simulations and compared to those observed in available crystal structures, including PA-IL/Gal1-2GalOMe complex, that was solved at 2.4 Å resolution and reported herein. The role of a structural bridge water molecule in the binding site of -PAIL was also elucidated through MD simulations and molecular mechanics Poisson-Bolzmann surface area MM-PBSA approach. This water molecule establishes three very stable hydrogen bonds with O6 of non-reducing galactose, oxygen from Pro51 main chain and nitrogen from Gln53 main chain of the lectin binding site. Binding free energies for PA-IL in complex with the three disaccharides were investigated and the results were compared with the experimental data determined by titration microcalorimetry. When the bridge water molecule was included in the MM-PBSA calculations, the simulations predicted the correct binding affinity trends with the 1-2 linked disaccharide presenting three times stronger affinity ligand than the two other ones. These results highlight the role of the water molecule in the binding site of PA-IL and indicate that it should be taken into account when designing glycoderivatives active against P. aeruginosa adhesion.
ChemBioChem, 2017
Lectin LecA of Pseudomonas aeruginosa is established as a virulent factor. Glycoclusters targeting LecA able to compete with human glycoconjugates present on epithelial cells are promising candidates to treat P. aeruginosa infection. A family of 32 glycodendrimers of generation 0 and 1 displaying bifurcated bisgalactosides has been designed to interact with LecA. The influence of both the central multivalent core and the aglycon of these glycodendrimers on their affinity toward LecA has been evaluated using a microarray technology both qualitatively for a rapid screening of the binding properties but also quantitatively (Kd) leading to high affinity LecA ligands with Kd values in the low nanomolar range (Kd = 22 nM for the best one).
BMC Structural Biology, 2007
Background: Lectins are proteins of non-immune origin capable of binding saccharide structures with high specificity and affinity. Considering the high encoding capacity of oligosaccharides, this makes lectins important for adhesion and recognition. The present study is devoted to the PA-IIL lectin from Pseudomonas aeruginosa, an opportunistic human pathogen capable of causing lethal complications in cystic fibrosis patients. The lectin may play an important role in the process of virulence, recognizing specific saccharide structures and subsequently allowing the bacteria to adhere to the host cells. It displays high values of affinity towards monosaccharides, especially fucose -a feature caused by unusual binding mode, where two calcium ions participate in the interaction with saccharide. Investigating and understanding the nature of lectin-saccharide interactions holds a great potential of use in the field of drug design, namely the targeting and delivery of active compounds to the proper site of action.
International Journal of Molecular Sciences
The Gram-negative bacterium Pseudomonas aeruginosa is an important opportunistic human pathogen associated with cystic fibrosis. P. aeruginosa produces two soluble lectins, the d-galactose-specific lectin PA-IL (LecA) and the l-fucose-specific lectin PA-IIL (LecB), among other virulence factors. These lectins play an important role in the adhesion to host cells and biofilm formation. Moreover, PA-IL is cytotoxic to respiratory cells in the primary culture. Therefore, these lectins are promising therapeutic targets. Specifically, carbohydrate-based compounds could inhibit their activity. In the present work, a 3-O-fucosyl lactose-containing tetravalent glycocluster was synthesized and utilized as a mutual ligand of galactophilic and fucophilic lectins. Pentaerythritol equipped with azido ethylene glycol-linkers was chosen as a multivalent scaffold and the glycocluster was constructed by coupling the scaffold with propargyl 3-O-fucosyl lactoside using an azide-alkyne 1,3-dipolar cyclo...