Inhibitor recognition specificity of MERS-CoV papain-like protease may differ from that of SARS-CoV.
The Middle East Respiratory Syndrome coronavirus (MERS-CoV) papain-like protease (PLpro) blocking loop 2 (BL2) structure differs significantly from that of SARS-CoV PLpro, where it has been proven to play a crucial role in SARS-CoV PLpro inhibitor binding. Four SARS-CoV PLpro lead inhibitors were tested against MERS-CoV PLpro, none of which were effective against MERS-CoV PLpro. Structure and sequence alignments revealed that two residues, Y269 and Q270, responsible for inhibitor binding to SARS-CoV PLpro, were replaced by T274 and A275 in MERS-CoV PLpro, making critical binding interactions difficult to form for similar types of inhibitors. High-throughput screening (HTS) of 25 000 compounds against both PLpro enzymes identified a small fragment-like noncovalent dual inhibitor. Mode of inhibition studies by enzyme kinetics and competition surface plasmon resonance (SPR) analyses suggested that this compound acts as a competitive inhibitor with an IC50 of 6 μM against MERS-CoV PLpro, indicating that it binds to the active site, whereas it acts as an allosteric inhibitor against SARS-CoV PLpro with an IC50 of 11 μM. These results raised the possibility that inhibitor recognition specificity of MERS-CoV PLpro may differ from that of SARS-CoV PLpro. In addition, inhibitory activity of this compound was selective for SARS-CoV and MERS-CoV PLpro enzymes over two human homologues, the ubiquitin C-terminal hydrolases 1 and 3 (hUCH-L1 and hUCH-L3).
†Center for Pharmaceutical Biotechnology and Department of Medicinal Chemistry and Pharmacognosy, University of Illinois at Chicago, 900 S. Ashland, Chicago, Illinois 60607, United States.
Hyun
H
Lee
†Center for Pharmaceutical Biotechnology and Department of Medicinal Chemistry and Pharmacognosy, University of Illinois at Chicago, 900 S. Ashland, Chicago, Illinois 60607, United States.
Hao
H
Lei
†Center for Pharmaceutical Biotechnology and Department of Medicinal Chemistry and Pharmacognosy, University of Illinois at Chicago, 900 S. Ashland, Chicago, Illinois 60607, United States.
Bernard D
BD
Santarsiero
†Center for Pharmaceutical Biotechnology and Department of Medicinal Chemistry and Pharmacognosy, University of Illinois at Chicago, 900 S. Ashland, Chicago, Illinois 60607, United States.
Joseph L
JL
Gatuz
†Center for Pharmaceutical Biotechnology and Department of Medicinal Chemistry and Pharmacognosy, University of Illinois at Chicago, 900 S. Ashland, Chicago, Illinois 60607, United States.
Shuyi
S
Cao
†Center for Pharmaceutical Biotechnology and Department of Medicinal Chemistry and Pharmacognosy, University of Illinois at Chicago, 900 S. Ashland, Chicago, Illinois 60607, United States.
Amy J
AJ
Rice
†Center for Pharmaceutical Biotechnology and Department of Medicinal Chemistry and Pharmacognosy, University of Illinois at Chicago, 900 S. Ashland, Chicago, Illinois 60607, United States.
Kavankumar
K
Patel
†Center for Pharmaceutical Biotechnology and Department of Medicinal Chemistry and Pharmacognosy, University of Illinois at Chicago, 900 S. Ashland, Chicago, Illinois 60607, United States.
Michael Z
MZ
Szypulinski
Isabel
I
Ojeda
‡Departments of Chemistry and Medicinal Chemistry, Purdue University, 560 Oval Drive, West Lafayette, Indiana 47907, United States.
Arun K
AK
Ghosh
†Center for Pharmaceutical Biotechnology and Department of Medicinal Chemistry and Pharmacognosy, University of Illinois at Chicago, 900 S. Ashland, Chicago, Illinois 60607, United States.
Michael E
ME
Johnson
D000494:Allosteric Regulation; D000595:Amino Acid Sequence; D000998:Antiviral Agents / Q000737:chemistry*; D020134:Catalytic Domain; D000086782:Coronavirus 3C Proteases; D003546:Cysteine Endopeptidases / Q000737:chemistry; D010450:Endopeptidases / Q000737:chemistry; D057166:High-Throughput Screening Assays; D006801:Humans; D007700:Kinetics; D065207:Middle East Respiratory Syndrome Coronavirus / Q000737:chemistry* / Q000201:enzymology; D008958:Models, Molecular; D008969:Molecular Sequence Data; D011480:Protease Inhibitors / Q000737:chemistry*; D011485:Protein Binding; D017433:Protein Structure, Secondary; D011994:Recombinant Proteins / Q000737:chemistry; D045473:Severe acute respiratory syndrome-related coronavirus / Q000737:chemistry* / Q000201:enzymology; D013045:Species Specificity; D020349:Surface Plasmon Resonance; D043222:Ubiquitin Thiolesterase / Q000037:antagonists & inhibitors / Q000737:chemistry; D014764:Viral Proteins / Q000037:antagonists & inhibitors* / Q000737:chemistry
D000998:Antiviral Agents; D011480:Protease Inhibitors; D011994:Recombinant Proteins; C482860:UCHL1 protein, human; D014764:Viral Proteins; D010450:Endopeptidases; C509806:UCHL3 protein, human; D043222:Ubiquitin Thiolesterase; D003546:Cysteine Endopeptidases; D000086782:Coronavirus 3C Proteases