PA-I lectin from Pseudomonas aeruginosa binds acyl homoserine lactones.
The study analyses the binding affinities of Pseudomonas aeruginosa PA-I lectin (PA-IL) to three N-acyl homoserine lactones (AHSL), quorum sensing signal molecules responsible for cell-cell communication in bacteria. It shows that like some plant lectins, PA-IL has a dual function and, besides its carbohydrate-binding capacity, can accommodate AHLS. Formation of complexes between PA-IL and AHSL with acyl side chains composed of 4, 6 or 12 methyl groups is characterized by changes in the emissions of two incorporated fluorescent markers, TNS and IAEDANS, both derivatives of naphthalene sulfonic acid. PA-IL shows increasing affinities to lactones with longer aliphatic side chains. The values of the apparent dissociation constants (K(d)), which are similar to the previously determined K(d) for the adenine high affinity binding, and the similar effects of lactones and adenine on the TNS emission indicate one identical binding site for these ligands, which is suggested to represent the central cavity of the oligomeric molecule formed after the association of the four identical subunits of PA-IL. Intramolecular distances between the fluorescent markers and protein Trp residues are determined by fluorescence resonance energy transfer (FRET).
Boteva
Raina N
RN
National Center of Radiobiology and Radiation Protection, 132 Kliment Ohridski Blvd., Sofia 1756, Bulgaria. r.boteva@ncrrp.org
Bogoeva
Vanya P
VP
Stoitsova
Stoyanka R
SR
D018829:Adhesins, Bacterial / Q000378:metabolism; D001426:Bacterial Proteins / Q000378:metabolism*; D001665:Binding Sites; D050260:Carbohydrate Metabolism; D002265:Carboxylic Ester Hydrolases / Q000378:metabolism*; D002450:Cell Communication / Q000502:physiology; D005456:Fluorescent Dyes; D037102:Lectins / Q000378:metabolism*; D009282:Naphthalenesulfonates / Q000737:chemistry; D011550:Pseudomonas aeruginosa / Q000737:chemistry* / Q000378:metabolism; D013050:Spectrometry, Fluorescence
D018829:Adhesins, Bacterial; D001426:Bacterial Proteins; D005456:Fluorescent Dyes; D037102:Lectins; D009282:Naphthalenesulfonates; C038692:adhesin, Pseudomonas; D002265:Carboxylic Ester Hydrolases; C432003:N-acyl homoserine lactonase