Characterization of glycosaminoglycan interactions with the chemokine CCL20 (MIP3α) and its carboxyterminal antimicrobial and antibiofilm peptide.

The chemokine CCL20/MIP3α plays an important role in the migration of dendritic cells and several lymphocytes. This 70-residue protein is also implicated in various diseases, such as rheumatoid arthritis, psoriasis, sepsis and numerous forms of cancer. In addition, as the most basic human chemokine, CCL20 also displays direct antimicrobial and antibiofilm activities. The binding and oligomerization of chemokines to cell surface glycosaminoglycans (GAG) can play an important role during receptor activation; therefore we have studied the interactions of CCL20 with fondaparinux. This anticoagulant drug is a uniform sulfated linear pentasaccharide that structurally closely resembles the heterogenous low molecular weight heparins that have often been used to study GAG-protein binding in solution. Using multidimensional multinuclear NMR spectroscopy, we could map out the distinct GAG/fondaparinux binding sites on the monomeric (pH 5.5) and dimeric (pH 7.5) forms of the CCL20 protein surface. In the second part of this study, we showed that CCL20-(51-70), the recombinant 20-residue carboxyterminal helical peptide of CCL20, interacted weakly with fondaparinux. We also surveyed several host-defence properties of this peptide. In comparison to several other well-characterized peptides, CCL20-(51-70) displayed potent antibiofilm and antimicrobial activities against a pathogenic Gram-positive Staphylococcus aureus MRSA strain. It also displayed somewhat lower activities against the Gram-negative Pseudomonas aeruginosa PAO1 strain. These results highlight the potential of CCL20-(51-70) as a potent host-defence peptide, that could play a role in eradicating bacterial biofilms, particularly for Gram-positive pathogenic bacteria.