Pseudomonas aeruginosa lectin LecB is located in the outer membrane and is involved in biofilm formation.
Pseudomonas aeruginosa is an opportunistic pathogen which causes a variety of diseases, including respiratory tract infections in patients suffering from cystic fibrosis. Therapeutic treatment of P. aeruginosa infections is still very difficult because the bacteria exhibit high intrinsic resistance against a variety of different antibiotics and, in addition, form stable biofilms, e.g. in the human lung. Several virulence factors are produced by P. aeruginosa, among them the two lectins LecA and LecB, which exert different cytotoxic effects on respiratory epithelial cells and presumably facilitate bacterial adhesion to the airway mucosa. Here, the physiology has been studied of the lectin LecB, which binds specifically to L-fucose. A LecB-deficient P. aeruginosa mutant was shown to be impaired in biofilm formation when compared with the wild-type strain, suggesting an important role for LecB in this process. This result prompted an investigation of the subcellular localization of LecB by cell fractionation and subsequent immunoblotting. The results show that LecB is abundantly present in the bacterial outer-membrane fraction. It is further demonstrated that LecB could be released specifically by treatment of the outer-membrane fraction with p-nitrophenyl alpha-L-fucose, whereas treatment with D-galactose had no effect. In contrast, a LecB protein carrying the mutation D104A, which results in a defective sugar-binding site, was no longer detectable in the membrane fraction, suggesting that LecB binds to specific carbohydrate ligands located at the bacterial cell surface. Staining of biofilm cells using fluorescently labelled LecB confirmed the presence of these ligands.
Tielker
Denis
D
Institut für Molekulare Enzymtechnologie, Heinrich-Heine-Universität Düsseldorf, Forschungszentrum Juelich, D-52426 Juelich, Germany.
Hacker
Stephanie
S
Lehrstuhl für Biologie der Mikroorganismen, Ruhr-Universität Bochum, D-44801 Bochum, Germany.
Loris
Remy
R
Laboratorium voor Ultrastructuur, Vlaams Interuniversitair Instituut voor Biotechnologie and Vrije Universiteit Brussel, B-1050 Brussel, Belgium.
Strathmann
Martin
M
Biofilm Centre, Abteilung Aquatische Mikrobiologie, Universität Duisburg-Essen, D-47057 Duisburg, Germany.
Wingender
Jost
J
Biofilm Centre, Abteilung Aquatische Mikrobiologie, Universität Duisburg-Essen, D-47057 Duisburg, Germany.
Wilhelm
Susanne
S
Institut für Molekulare Enzymtechnologie, Heinrich-Heine-Universität Düsseldorf, Forschungszentrum Juelich, D-52426 Juelich, Germany.
Rosenau
Frank
F
Institut für Molekulare Enzymtechnologie, Heinrich-Heine-Universität Düsseldorf, Forschungszentrum Juelich, D-52426 Juelich, Germany.
Jaeger
Karl-Erich
KE
Institut für Molekulare Enzymtechnologie, Heinrich-Heine-Universität Düsseldorf, Forschungszentrum Juelich, D-52426 Juelich, Germany.
D001425:Bacterial Outer Membrane Proteins / Q000235:genetics / Q000378:metabolism*; D018441:Biofilms / Q000254:growth & development*; D002462:Cell Membrane / Q000378:metabolism; D005643:Fucose / Q000378:metabolism; D015964:Gene Expression Regulation, Bacterial; D006801:Humans; D037102:Lectins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D008024:Ligands; D009154:Mutation; D011550:Pseudomonas aeruginosa / Q000235:genetics / Q000254:growth & development / Q000378:metabolism; D013347:Subcellular Fractions / Q000378:metabolism
D001425:Bacterial Outer Membrane Proteins; D037102:Lectins; D008024:Ligands; D005643:Fucose