FIG 7.

Interactions of the C-tail residues with the conserved hydrophobic pocket region. (A) ICP27-CTD C-tail of one molecule (magenta diagram representation) is lodged in the hydrophobic pocket of second molecule (surface representation colored by B-factor values). The lower wall of the pocket forms a flexible cap (as seen by a high B-factor value shown in orange-red colors). (B) Conserved C-tail residues (magenta diagram and stick representation) Y505, F506, and Y507 are sandwiched via hydrophobic interactions with conserved residues L315 and E358 from the pocket region. (C) Several buried charges are conserved around the C-tail interaction region, making polar interactions (orange dashes). E358 forms a salt bridge with Y505 and F506 of the C-tail. R340 from the pocket and K504 from the C-tail make stabilizing interactions with E358. E347 has its carboxylate group only 4.3 Å away from K504. (D) C-tail residues S510 and L511 make hydrophobic interactions with the conserved YXPG motif. The motif is, in turn, stabilized by the conserved D357.