title: The N-terminal octapeptide acts as a dimerization inhibitor of SARS coronavirus 3C-like proteinase.
abstract: The 3C-like proteinase of severe acute respiratory syndrome (SARS) coronavirus has been proposed to be a key target for structural-based drug design against SARS. Accurate determination of the dimer dissociation constant and the role of the N-finger (residues 1-7) will provide more insights into the enzyme catalytic mechanism of SARS 3CL proteinase. The dimer dissociation constant of the wild-type protein was determined to be 14.0microM by analytical ultracentrifugation method. The N-finger fragment of the enzyme plays an important role in enzyme dimerization as shown in the crystal structure. Key residues in the N-finger have been studied by site-directed mutagenesis, enzyme assay, and analytical ultracentrifugation. A single mutation of M6A was found to be critical to maintain the dimer structure of the enzyme. The N-terminal octapeptide N8 and its mutants were also synthesized and tested for their potency as dimerization inhibitors. Peptide cleavage assay confirms that peptide N8 is a dimerization inhibitor with a K(i) of 2.20mM. The comparison of the inhibitory activities of N8 and its mutants indicates that the hydrophobic interaction of Met-6 and the electrostatic interaction of Arg-4 contribute most for inhibitor binding. This study describes the first example of inhibitors targeting the dimeric interface of SARS 3CL proteinase, providing a novel strategy for drug design against SARS and other coronaviruses.
authors.affiliation: State Key Laboratory for Structural Chemistry of Stable and Unstable Species, College of Chemistry, Peking University, Beijing 100871, China.
authors.forename: Ping
authors.initials: P
authors.lastname: Wei
authors.forename: Keqiang
authors.initials: K
authors.lastname: Fan
authors.forename: Hao
authors.initials: H
authors.lastname: Chen
authors.forename: Liang
authors.initials: L
authors.lastname: Ma
authors.forename: Changkang
authors.initials: C
authors.lastname: Huang
authors.forename: Lei
authors.initials: L
authors.lastname: Tan
authors.forename: Dong
authors.initials: D
authors.lastname: Xi
authors.forename: Chunmei
authors.initials: C
authors.lastname: Li
authors.forename: Ying
authors.initials: Y
authors.lastname: Liu
authors.forename: Aoneng
authors.initials: A
authors.lastname: Cao
authors.forename: Luhua
authors.initials: L
authors.lastname: Lai
mesh_terms: D001665:Binding Sites; D003198:Computer Simulation; D000086782:Coronavirus 3C Proteases; D003546:Cysteine Endopeptidases; D019281:Dimerization; D015195:Drug Design; D010450:Endopeptidases; D004789:Enzyme Activation; D004791:Enzyme Inhibitors / Q000737:chemistry; D008956:Models, Chemical; D008958:Models, Molecular; D010455:Peptides / Q000737:chemistry*; D011485:Protein Binding; D013329:Structure-Activity Relationship; D014764:Viral Proteins / Q000037:antagonists & inhibitors*
chemical_list: D004791:Enzyme Inhibitors; D010455:Peptides; D014764:Viral Proteins; D010450:Endopeptidases; D003546:Cysteine Endopeptidases; D000086782:Coronavirus 3C Proteases