FIG. 1.

Locations and properties of ICP0 mutants used in this study. Numbers refers to amino acid positions. Filled boxes indicate the positions of the RING Finger (RF), the USP7 binding region (USP7) and the self-multimerization (MD) domain. The data below the schematic view of the ICP0 gene indicate the mutations present in each ICP0 expression plasmid and their ability to bind USP7 (USP7), to multimerize (Multimer), to induce rep gene expression in transfected HA-16 cells (Rep), and to activate a cotransfected p5luc plasmid expressing the luciferase gene under the control of the p5 rep gene promoter. The numbers indicate either the percentages of Rep- expressing cells among those expressing ICP0 (as illustrated in Fig. 2) or the p5luc n-fold activation over basal levels by wt ICP0 and the various mutants. ND, not done. The original characterization of these mutant ICP0 proteins can be found in references (5, 10, and 11).