5‑Aminothiazoles Reveal a New Ligand-Binding Site on Prolyl Oligopeptidase Which is Important for Modulation of Its Protein–Protein Interaction-Derived Functions

A series of novel 5-aminothiazole-based ligands for prolyl
oligopeptidase
(PREP) comprise selective, potent modulators of the protein–protein
interaction (PPI)-mediated functions of PREP, although they are only
weak inhibitors of the proteolytic activity of PREP. The disconnected
structure–activity relationships are significantly more pronounced
for the 5-aminothiazole-based ligands than for the earlier published
5-aminooxazole-based ligands. Furthermore, the stability of the 5-aminothiazole
scaffold allowed exploration of wider substitution patterns than that
was possible with the 5-aminooxazole scaffold. The intriguing structure–activity
relationships for the modulation of the proteolytic activity and PPI-derived
functions of PREP were elaborated by presenting a new binding site
for PPI modulating PREP ligands, which was initially discovered using
molecular modeling and later confirmed through point mutation studies.
Our results suggest that this new binding site on PREP is clearly
more important than the active site of PREP for the modulation of
its PPI-mediated functions.

一系列基于5-氨基噻唑（5-aminothiazole）的新型脯氨酰寡肽酶（prolyl oligopeptidase, PREP）配体，可选择性且强效地调控PREP介导的蛋白质-蛋白质相互作用（protein–protein interaction, PPI）功能，但仅能微弱抑制PREP的蛋白水解活性。
相较于此前已发表的基于5-氨基恶唑（5-aminooxazole）的配体，基于5-氨基噻唑的配体所呈现的非连续构效关系更为显著。
此外，5-氨基噻唑骨架的稳定性使得其可探索的取代模式范围，远宽于5-氨基恶唑骨架所能支持的范围。
针对PREP的蛋白水解活性调控与PPI介导功能调控这两类过程，其引人关注的构效关系，通过提出一类靶向PREP、用于调控PPI的全新结合位点而得到阐明；该结合位点最初通过分子建模（molecular modeling）发现，后续经点突变实验（point mutation studies）验证。
研究结果表明，相较于PREP的活性位点，该全新结合位点在调控PREP的PPI介导功能中发挥更为关键的作用。