UbiQ is proud to have been part of a major collaboration reported recently by Rut et al. in Science Advances  (2020, 6, eabd4596) describing the activity profiling and crystal structures of inhibitor bound SARS-CoV-2 PLpro.

Abstract. Viral papain-like cysteine protease (PLpro, NSP3) is essential for SARS-CoV-2 replication and represents a promising target for the development of antiviral drugs. Here, we used a combinatorial substrate library and performed comprehensive activity profiling of SARS-CoV-2 PLpro. On the scaffold of the best hits from positional scanning, we designed optimal fluorogenic substrates and irreversible inhibitors with a high degree of selectivity for SARS PLpro. We determined crystal structures of two of these inhibitors in complex with SARS-CoV-2 PLpro that reveals their inhibitory mechanisms and provides a molecular basis for the observed substrate specificity profiles. Last, we demonstrate that SARS-CoV-2 PLpro harbors deISGylating activity similar to SARSCoV-1 PLpro but its ability to hydrolyze K48-linked Ub chains is diminished, which our sequence and structure analysis provides a basis for. Together, this work has revealed the molecular rules governing PLpro substrate specificity and provides a framework for development of inhibitors with potential therapeutic value or drug repurposing.

1. Wroclaw University of Science and Technology, Poland.
2. Medical University of South Carolina, Charleston, USA. 
3. University of Texas Health Science Center at San Antonio, San Antonio, USA.
4. New York University School of Medicine, New York, USA.
5. Sanford Burnham Prebys Medical Discovery Institute, La Jolla, USA.
6. UbiQ Bio B.V., Amsterdam, The Netherlands.
7. Independent Consultant.

(*) These authors contributed equally to this work. (†) Corresponding author. (‡) Present address: Arvinas Inc., New Haven, USA.