Crystal Structure of a monomeric form of Severe Acute Respiratory Syndrome (SARS) 3C-like protease mutant

Experimental Data Snapshot

  • Resolution: 1.75 Å
  • R-Value Free: 0.208 
  • R-Value Work: 0.168 

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Mechanism for controlling the dimer-monomer switch and coupling dimerization to catalysis of the severe acute respiratory syndrome coronavirus 3C-like protease.

Shi, J.Sivaraman, J.Song, J.

(2008) J Virol 82: 4620-4629

  • DOI: https://doi.org/10.1128/JVI.02680-07
  • Primary Citation of Related Structures:  

  • PubMed Abstract: 

    Unlike 3C protease, the severe acute respiratory syndrome coronavirus (SARS-CoV) 3C-like protease (3CLpro) is only enzymatically active as a homodimer and its catalysis is under extensive regulation by the unique extra domain. Despite intense studies, two puzzles still remain: (i) how the dimer-monomer switch is controlled and (ii) why dimerization is absolutely required for catalysis. Here we report the monomeric crystal structure of the SARS-CoV 3CLpro mutant R298A at a resolution of 1.75 A. Detailed analysis reveals that Arg298 serves as a key component for maintaining dimerization, and consequently, its mutation will trigger a cooperative switch from a dimer to a monomer. The monomeric enzyme is irreversibly inactivated because its catalytic machinery is frozen in the collapsed state, characteristic of the formation of a short 3(10)-helix from an active-site loop. Remarkably, dimerization appears to be coupled to catalysis in 3CLpro through the use of overlapped residues for two networks, one for dimerization and another for the catalysis.

  • Organizational Affiliation

    Department of Biological Sciences, National University of Singapore, 14 Science Drive 4, Singapore 117543, Republic of Singapore. bchsj@nus.edu.sg

Find similar proteins by:  (by identity cutoff)  |  3D Structure
Entity ID: 1
MoleculeChains Sequence LengthOrganismDetailsImage
3C-like proteinase306Severe acute respiratory syndrome-related coronavirusMutation(s): 1 
Gene Names: rep
EC: 3.4.22
Find proteins for P0C6X7 (Severe acute respiratory syndrome coronavirus)
Explore P0C6X7 
Go to UniProtKB:  P0C6X7
Entity Groups  
Sequence Clusters30% Identity50% Identity70% Identity90% Identity95% Identity100% Identity
UniProt GroupP0C6X7
Sequence Annotations
  • Reference Sequence
Experimental Data & Validation

Experimental Data

  • Resolution: 1.75 Å
  • R-Value Free: 0.208 
  • R-Value Work: 0.168 
  • Space Group: P 1 21 1
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 33.389α = 90
b = 66.225β = 100.77
c = 62.21γ = 90
Software Package:
Software NamePurpose
DENZOdata reduction
SCALEPACKdata scaling
PDB_EXTRACTdata extraction
HKL-2000data scaling

Structure Validation

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Entry History 

Deposition Data

Revision History  (Full details and data files)

  • Version 1.0: 2008-03-11
    Type: Initial release
  • Version 1.1: 2011-07-13
    Changes: Version format compliance
  • Version 1.2: 2017-10-18
    Changes: Refinement description
  • Version 1.3: 2021-10-20
    Changes: Database references
  • Version 1.4: 2024-02-21
    Changes: Data collection