Dissection Study on the Severe Acute Respiratory Syndrome 3C-like Protease Reveals the Critical Role of the Extra Domain in Dimerization of the Enzyme

• DOI: 10.1074/jbc.m311744200
• Publication Date: 2004-05-28T19:18:26Z
• Authors: Jiahai Shi; Zheng Wei; Jianxing Song
• Keywords: Models, Molecular; 570; Protein Folding; DNA, Complementary; Magnetic Resonance Spectroscopy; Light; Protein Conformation; Catalysis; 03 medical and health sciences; Endopeptidases; Chymotrypsin; Scattering, Radiation; Cloning, Molecular; Enzyme Inhibitors; Coronavirus 3C Proteases; Glutathione Transferase; 0303 health sciences; Dose-Response Relationship, Drug; Circular Dichroism; 3. Good health; Protein Structure, Tertiary; Cysteine Endopeptidases; Protein Structure and Folding; Peptides; Dimerization

The severe acute respiratory syndrome (SARS) 3C-like protease consists of two distinct folds, namely the N-terminal chymotrypsin fold containing domains I and II hosting complete catalytic machinery C-terminal extra helical domain III unique for coronavirus 3CL proteases. Previously functional role this has been completely unknown, it was believed that proteases share same enzymatic mechanism with picornavirus 3C proteases, which contain but have no domain. To understand to characterize enzyme-substrate interactions by use dynamic light scattering, circular dichroism, NMR spectroscopy, we 1) dissected full-length SARS into folds subsequently investigated their structural dimerization properties 2) studied binding three substrate peptides entire enzyme its folds. results lead several findings; although parts folded native-like structures, only had weak activity as compared enzyme, remained a monomer within wide range protein concentrations, existed stable dimer even at very low concentration. This observation strongly indicates contributes protease, thus, switching from inactive form (monomer) active (dimer). discovery not separates in terms also defines interface on new target design specific inhibitors. Furthermore, determination preferred solution conformation peptide S1 together differential line-broadening transferred nuclear Overhauser enhancement study allows us pinpoint bound structure peptide.