From inhibition to degradation: Cutting-edge technology in COVID-19 drug discovery

Proteolysis-targeting chimera (PROTAC) molecules are hetero-bifunctional chemical entities with three different units which include a ligand that binds to a protein of interest; a second ligand that binds to the E3 ubiquitin ligase; and a linker that conjugates the two ligands together. The technology utilizes the ubiquitin-proteasome system (UPS) to target a specific protein and induce its degradation in the cell. PROTAC has drawn the interest of researchers in anti-cancer drug discovery and has yielded a better outcome in degrading regulatory proteins, kinases, nuclear receptors, transcription factors, and enzymes. This paper discusses this technology and its application to COVID-19 drug discovery. In 2019, the Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2), an infectious agent emerged from Wuhan resulting in millions of deaths worldwide. The WHO declared it a global pandemic because of its fast transmissibility and infectivity across the continents. To curtail this menace, efforts were made to develop therapeutics and inhibitors very quickly. Vaccines and therapeutics discovery were fast-tracked, and already FDA-approved drug molecules were also repurposed - many of which were protein inhibitors. However, PROTAC technology potentially offers a more direct and sustainable contribution to anti-COVID drug discovery than protein inhibition-based therapeutics.