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Published on: December 1, 2020
New Peptide-Based Pharmacophore Activates 20S Proteasome
Paweł A Osmulski1,2, Przemysław Karpowicz3,4, Elżbieta Jankowska4
1Department of Molecular Medicine, UT Health San Antonio, Texas, TX 78245, USA.
Abstract:
The proteasome is a pivotal element of controlled proteolysis, responsible for the catabolic arm of proteostasis. By inducing apoptosis, small molecule inhibitors of proteasome peptidolytic activities are successfully utilized in treatment of blood cancers. However, the clinical potential of proteasome activation remains relatively unexplored. In this work, we introduce short TAT peptides derived from HIV-1 Tat protein and modified with synthetic turn-stabilizing residues as proteasome agonists. Molecular docking and biochemical studies point to the α1/α2 pocket of the core proteasome α ring as the binding site of TAT peptides. We postulate that the TATs' pharmacophore consists of an N-terminal basic pocket-docking "activation anchor" connected via a β turn inducer to a C-terminal "specificity clamp" that binds on the proteasome α surface. By allosteric effects-including destabilization of the proteasomal gate-the compounds substantially augment activity of the core proteasome in vitro. Significantly, this activation is preserved in the lysates of cultured cells treated with the compounds. We propose that the proteasome-stimulating TAT pharmacophore provides an attractive lead for future clinical use.
Insights
Researchers developed novel TAT peptides that activate the proteasome, a key cellular complex. These proteasome agonists show potential for new therapeutic strategies beyond current cancer treatments.
Area of Science:
- Biochemistry
- Molecular Biology
- Cellular Biology
Background:
- The proteasome is essential for protein degradation and maintaining proteostasis.
- Proteasome inhibitors are used to treat blood cancers by inducing apoptosis.
- Proteasome activation remains an underexplored therapeutic avenue.
Purpose of the Study:
- To investigate the potential of novel TAT peptides as proteasome agonists.
- To characterize the binding site and mechanism of action of these peptides.
- To evaluate the therapeutic potential of proteasome activation.
Main Methods:
- Design and synthesis of TAT peptides with turn-stabilizing residues.
- Molecular docking to predict binding sites.
- Biochemical assays to measure proteasome activity in vitro.
- Cell-based assays using cell lysates.
Main Results:
- TAT peptides bind to the α1/α2 pocket of the proteasome's α ring.
- The peptides act as proteasome agonists, augmenting core proteasome activity.
- Activation was observed in vitro and in cell lysates.
- A pharmacophore model involving an 'activation anchor' and 'specificity clamp' was proposed.
Conclusions:
- Modified TAT peptides function as proteasome agonists.
- These peptides represent a novel pharmacophore for proteasome activation.
- The findings offer a promising lead for developing new therapeutic strategies targeting proteasome activation.
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