Fig. 4
Structural model of DrPARG-PAR (poly-ADP-ribose) complex in endo-glycohydrolase mode. a Solvent-accessible surface of DrPARG in gray (position of Thr267 is in yellow) with a PAR3 modeled in an endo-glycohydrolase position. Carbons of the three individual ADP-ribose units are distinctly colored. b, c Stereo images of an overlay of the modeled endo-glycohydrolase PAR3 (colored the same as in a) with the b obligate exo-glycohydrolase PARG structures in complex with ADP-ribose from Thermomonospora curvata (TcPARG) structure and c observed exo-glycohydrolase DrPARG structure. Residues and secondary structures implicated in steric hindrance with n + 1 and n ADP-ribose units of TcPARG as well as their equivalents of DrPARG are shown as spheres (colored yellow) and a cartoon model, respectively. The hydrogen network between the adenine moiety/ribose′ of the n ADP-ribose unit and the protein/crystallized water observed for the exo-glycohydrolase mode is shown as dashed lines
