Three-dimensional model of a substrate-bound SARS chymotrypsin-like cysteine proteinase predicted by multiple molecular dynamics simulations: catalytic efficiency regulated by substrate binding.
Severe acute respiratory syndrome (SARS) is a contagious and deadly disease caused by a new coronavirus. The protein sequence of the chymotrypsin-like cysteine proteinase (CCP) responsible for SARS viral replication has been identified as a target for developing anti-SARS drugs. Here, I report the ATVRLQ(p1)A(p1')-bound CCP 3D model predicted by 420 different molecular dynamics simulations (2.0 ns for each simulation with a 1.0-fs time step). This theoretical model was released at the Protein Data Bank (PDB; code: 1P76) before the release of the first X-ray structure of CCP (PDB code: 1Q2W). In contrast to the catalytic dyad observed in X-ray structures of CCP and other coronavirus cysteine proteinases, a catalytic triad comprising Asp187, His41, and Cys145 is found in the theoretical model of the substrate-bound CCP. The simulations of the CCP complex suggest that substrate binding leads to the displacement of a water molecule entrapped by Asp187 and His41, thus converting the dyad to a more efficient catalytic triad. The CCP complex structure has an expanded active-site pocket that is useful for anti-SARS drug design. In addition, this work demonstrates that multiple molecular dynamics simulations are effective in correcting errors that result from low-sequence-identity homology modeling.
Pang
Yuan-Ping
YP
Computer-Aided Molecular Design Laboratory, Mayo Clinic College of Medicine, Rochester, Minnesota 55905, USA. pang@mayo.edu
D000110:Acetylcholinesterase / Q000737:chemistry; D000595:Amino Acid Sequence; D001665:Binding Sites; D002384:Catalysis; D003198:Computer Simulation; D018360:Crystallography, X-Ray; D003546:Cysteine Endopeptidases / Q000737:chemistry* / Q000378:metabolism*; D004791:Enzyme Inhibitors; D008958:Models, Molecular; D008969:Molecular Sequence Data; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D045473:Severe acute respiratory syndrome-related coronavirus / Q000201:enzymology*; D016415:Sequence Alignment; D040681:Structural Homology, Protein
D004791:Enzyme Inhibitors; D000110:Acetylcholinesterase; D003546:Cysteine Endopeptidases