Profiling of Substrate Specificities of 3C-Like Proteases from Group 1, 2a, 2b, and 3 Coronaviruses

Chuck, Chi-Pang; Chow, Hak-Fun; Wan, David Chi-Cheong; Wong, Kam-Bo

On the other hand, our profiling analysis suggests that 3CL pro from SARS-CoV and IBV have different substrate preferences at P4 position -SARS-CoV prefers P4-Val (relative activity = 1.0960.24) while IBV prefers P4-Pro (relative activity = 1.3960.10) (Figure 1 , Table S1 ). To see if we can exploit this distinct substrate preference at P4 position to create a substrate more specific for IBV 3CL pro , we have created the triply-substituted variant 'VPRLQQSGF'. The protease activity of IBV 3CL pro against this sequence was boosted to 4.3360.98, while that of the other strains were significantly reduced, demonstrating that this substrate sequence can represent a specific substrate-sequence for IBV 3CL pro (Table 1) . Similarly, the protease activity of SARS-CoV 3CL pro against the triplysubstituted sequence 'VVRLQQSGF' was boosted to 2.5060.51, while that of the other strains were reduced (Table 1) . Taken together, these results suggest that one can combine the substrate preference profiled in this study to create a better substrate sequences.