Lysophosphatidic acid and lipopolysaccharide bind to the PIP2-binding domain of gelsolin

The binding of the gelsolin P2 peptide (residues 150–169) with lysophosphatidic acid (LPA) and lipopolysaccharide (LPS) was investigated by isothermal titration calorimetry. P2 binds to LPS with higher affinity than to LPA. For the interaction of 1-oleoyl-LPA with P2 in the absence of salt, Kd and ΔH° were 920 nM and −2.07 kcal/mol, respectively, at pH 7.4 and 25 °C. For the interaction of lipopolysaccharide (LPS) from P. aeruginosa with P2 under the same conditions, Kd was 177 nM and ΔH° was −7.6 kcal/mol.