Development of BromoTag: A “bump-&-hole”-PROTAC system to induce potent, rapid, and selective degradation of tagged target proteins

Adam G. Bond, Conner Craigon, Kwok-Ho Chan, Andrea Testa, Athanasios Karapetsas, Rotimi Fasimoye, Thomas Macartney, J. Julian Blow, Dario R. Alessi, Alessio Ciulli

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Small-molecule-induced protein depletion technologies, also called inducible degrons, allow degradation of genetically engineered target proteins within cells and animals. Here, we design and develop the BromoTag, a new inducible degron system comprising a Brd4 bromodomain L387A variant as a degron tag that allows direct recruitment by heterobifunctional bumped proteolysis targeting chimeras (PROTACs) to hijack the VHL E3 ligase. We describe extensive optimization and structure-activity relationships of our bump-and-hole-PROTACs using a CRISPR knock-in cell line expressing model target BromoTag-Brd2 at endogenous levels. Collectively, our cellular and mechanistic data qualifies bumped PROTAC AGB1 as a potent, fast, and selective degrader of BromoTagged proteins, with a favorable pharmacokinetic profile in mice. The BromoTag adds to the arsenal of chemical genetic degradation tools allowing us to manipulate protein levels to interrogate the biological function and therapeutic potential in cells and in vivo.
Original languageEnglish
Pages (from-to)15477-15502
Number of pages26
JournalJournal of Medicinal Chemistry
Issue number20
Early online date15 Oct 2021
Publication statusPublished - 28 Oct 2021

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