Multifaced-peptidomimetics as proteasome modulators

The rationale of the present project is that is possible to mimic the orientation and the interactions of the key residues of a protein
motif by varying the position and the nature of the substituents on a small-molecule scaffold. Accordingly, it is possible to develop
small-molecule ligands as structural and functional mimics of protein motifs.
Following this rationale, the projects aims at the identification of small non-peptidic molecules as allosteric modulators of the
catalytic core particle (namely, 20S) of human proteasome. In particular, nature-inspired molecular scaffolds will be rationally
modified in order to mimic the activating motifs of human 20S (h20S) regulatory proteins (RPs). The structural modifications will be
guided by in silico studies and the experimental data will be used to optimize the design strategy in an iterative process. At first, the
structures of all the RPs known to date will be investigated and small peptides corresponding to their 20S activating motif(s) will be
synthesized and tested for their ability to interact with 20S and interfere with its catalytic activities. In particular, different 20S
substrates will be designed and used in order to test the ability of the different RP motifs to selectively affect the 20S catalytic sites.
At the same time, the molecular scaffold of natural compounds, such as silybins, able to mimic the HbYX consensus sequence of the
activating motif of some RPs, or tyrosol-based curcumin mimics, able to mimic both α-helix based and β-sheet based protein motifs,
will be rationally varied and the effect on 20S catalytic activities of the resulting series of compounds will be explored using the
different substrates. The newly designed ligands will be studied either alone and in combination with RPs or RP-derived activating
peptides. To reach our aim, a multidisciplinary approach will be applied including molecular modeling studies, chemical synthesis
(both peptide and small ligands), NMR studies, and biochemical (cell-free and in-cell) investigation of the molecular interaction of the
new ligands with 20S and its functional implications.