Structural Basis for the Ubiquitin-Linkage Specificity and deISGylating Activity of SARS-CoV Papain-Like Protease
Figure 2
The crystal structure of the PLpro-Ubal complex reveals a dense hydrogen-bonding pattern between the active site of PLpro and the C-terminus of ubiquitin.
A. Stereoview of PLpro active-site interactions with ubiquitin-aldehyde. PLpro residues are shown in blue and labeled in black, and ubiquitin residues are shown and labeled in orange. Hydrogen bonds between PLpro and ubiquitin are shown as dashed lines. B. Electron density associated with the region surrounding the C-terminal residues of ubiquitin (orange density) and their interactions with the PLpro active site in the region of the mobile loop (blue density). The residues shown and the view depicted are similar to those in panels A and C. The electron density maps were calculated by omitting ubiquitin from the structure factor calculations. The Fo-Fc map for ubiquitin (orange) is contoured at 3σ and the 2Fo-Fc map for PLpro (blue density) is contoured at 1.5σ. The figure was generated using the program Pymol. C. Comparison of the PLpro active site loop in bound (blue with white surface) and unbound (yellow) conformations. The C-terminus of ubiquitin is shown in orange. The orientation of the structure is similar to that shown in panels A and B.