Self-Assembly of Proteolysis Targeting Chimeras Via Reversible Bioorthogonal Reactions

Abstract

Targeted protein degradation (TPD) by PROteolysis TArgeting Chimeras (PROTACs) is of great interest for probe molecule and drug development. However, current bivalent PROTACs are rule-breaking molecules with sub-optimal cellular permeability, solubility, and other drug-like properties. In this study, we report a novel approach for TPD by Self-Assembled Proteolysis TArgeting Chimeras (SAPTACs) in which the target protein and E3 Ubiquitin ligase ligands assemble in cellulo via reversible, bioorthogonal reactions. SAPTACs that me-diate the degradation of the Von Hippel Landau (VHL) E3 Ubiquitin ligase are described. We show that pseu-do-homodimeric degraders for VHL can be assembled in situ through the interaction of VHL ligands linked to phenylboronic acid and catechol as well as to o-acetlyphenylboronic acid and an alkoxyamine. The efficiency of VHL degradation by these SAPTACs is linked to the strength of the reversible covalent interaction.

Combinatorial Ubiquitination REal-time PROteolysis (CURE-PROs): A Modular Platform for Generating Reversible, Self-Assembling Bifunctional Targeted Degraders

“…din-3-yl)-1,3-dioxoisoindolin-4-yl)methyl)-2,3-dihydroxy-4-methoxybenzamide (46) was synthesized by following the general method of HATU-mediated coupling of 2,3-dihydroxy-4-methoxybenzoic acid (44,141…”

“…40−42 We recently reported the development of Self-Assembled Proteolysis-TArgeting Chimeras (SAPTACs), pseudohomodimeric molecules that demonstrated self-degradation of VHL using ligands that also assemble in cells via reversible, bio-orthogonal linkers, i.e., phenylboronic acid and catechol or o-acetlyphenylboronic acid and an alkoxyamine. 44 Strategies employing click chemistry have also been used to form active degraders within cells. 45,46 However, these irreversible reactions can form heterodimeric compounds outside cells, which, in turn, dramatically affects cellular permeability.…”

Innovative, combinatorial and high-throughput approaches to degrader synthesis

“…In a similar vein, Gui et al utilised a reversible reaction to synthesise degraders termed as ''SAPTACs'' (self-assembled proteolysis targeting chimeras) in cellulo. 27 This method was used to generate homodimeric degraders, previously noted by the Ciulli group, to result in the self-degradation of the protein. 28 The SAPTAC approach was demonstrated using two different methods: the first using a catechol-boronic acid system to generate a boronic ester in situ (Scheme 7(A)), and the second via a hydroxylamine condensation, facilitated by a proximal boronic acid group (Scheme 7(B)).…”

“…Over the last decade, an increasing number of new transformations have been reported in the literature for accessing degraders in a more streamlined fashion, moving away from lengthy linear synthetic routes, and towards parallel, combinatorial, and automated methods. Additionally, the development of CLIPTACs 26 and SAPTACs 27 were impressive examples of exploiting bioorthogonal chemistry to form PROTACs inside cells, bypassing the common issue of poor cellular permeability in beyond rule of 5 molecules. The approaches discussed in section two were strides forward in shortening the make-testanalyse cycle for new degraders, but synthetic throughput remained limited.…”