Structure-activity relationship studies of fostriecin, cytostatin, and key analogs, with PP1, PP2A, PP5, and( beta12-beta13)-chimeras (PP1/PP2A and PP5/PP2A), provide further insight into the inhibitory actions of fostriecin family inhibitors.

Fostriecin and cytostatin are structurally related natural inhibitors of serine/threonine phosphatases, with promising antitumor activity. The total synthesis of these antitumor agents has enabled the production of structural analogs, which are useful to explore the biological significance of features contained in the parent compounds. Here, the inhibitory activity of fostriecin, cytostatin, and 10 key structural analogs were tested in side-by-side phosphatase assays to further characterize their inhibitory activity against PP1c (Ser/Thr protein phosphatase 1 catalytic subunit), PP2Ac (Ser/Thr protein phosphatase 2A catalytic subunit), PP5c (Ser/Thr protein phosphatase 5 catalytic subunit), and chimeras of PP1 (Ser/Thr protein phosphatase 1) and PP5 (Ser/Thr protein phosphatase 5), in which key residues predicted for inhibitor contact with PP2A (Ser/Thr protein phosphatase 2A) were introduced into PP1 and PP5 using site-directed mutagenesis.

Differential interactions of fimbriae and lipopolysaccharide from Porphyromonas gingivalis with the Toll-like receptor 2-centred pattern recognition apparatus.

The lipopolysaccharide (LPS) and fimbriae of Porphyromonas gingivalis play important roles in periodontal inflammation and pathogenesis. We investigated fimbriae and LPS from several P. gingivalis strains in terms of relative dependence on Toll-like receptor (TLR) signalling partners or accessory pattern-recognition molecules mediating ligand transfer to TLRs, and determined induced assembly of receptor complexes in lipid rafts.

Peptide mapping of bacterial fimbrial epitopes interacting with pattern recognition receptors.

The fimbriae of the oral pathogen Porphyromonas gingivalis induce Toll-like receptor 2 (TLR2)-dependent macrophage activation upon their recognition by CD14 and the beta(2) integrin CD11b/CD18. To map functional epitopes of fimbriae that interact with these pattern recognition receptors (PRRs), we examined 20 synthetic peptides covering the entire length of the 41-kDa fimbrillin subunit. Using direct or competitive inhibition assays for receptor binding or cell activation, the CD14 binding activity of fimbriae was localized to residues 69-90 and was essential for TLR2-dependent cytokine induction.