Pseudomonas aeruginosa is an opportunistic ESKAPE pathogen
that produces two lectins, LecA and LecB, as part of its large
arsenal of virulence factors. Both carbohydrate-binding proteins
are central to the initial and later persistent infection processes,
i. e. bacterial adhesion and biofilm formation. The biofilm matrix
is a major resistance determinant and protects the bacteria
against external threats such as the host immune system or
antibiotic treatment. Therefore, the development of drugs
against the P. aeruginosa biofilm is of particular interest to
restore efficacy of antimicrobials. Carbohydrate-based inhibitors
for LecA and LecB were previously shown to efficiently reduce
biofilm formations. Here, we report a new approach for
inhibiting LecA with synthetic molecules bridging the established carbohydrate-binding site and a central cavity located
between two LecA protomers of the lectin tetramer. Inspired by
in silico design, we synthesized various galactosidic LecA
inhibitors with aromatic moieties targeting this central pocket.
These compounds reached low micromolar affinities, validated
in different biophysical assays. Finally, X-ray diffraction analysis
revealed the interactions of this compound class with LecA. This
new mode of action paves the way to a novel route towards
inhibition of P. aeruginosa biofilms