FIG 4.

USP1, USP12, and USP46 are recruited to the HPV origin by E1 and UAF1. (A) ChIP assays were performed in C33A cells cotransfected with expression vectors for 3F-E1 (either the WT or OBD mutant protein, as indicated), RFP-E2, GFP-USP (USP1, USP12, USP46, or USP14), or GFP alone (−), together with an origin (ori)-containing plasmid and a Renilla luciferase (Rluc)-containing plasmid as an internal control. GFP-USP fusion proteins were immunoprecipitated with a GFP antibody or an HA antibody as a specificity control. The results of the ori enrichment levels determined by qPCR are shown after normalization to the amount of input DNA using the internal control (RLuc). Each value is the average of three replicates, with the standard deviations presented as error bars. (B) The same as for panel A but using the mutant E1 VE protein that is defective for binding UAF1. (C) The same as for panel A but using an anti-Flag antibody to immunoprecipitate the indicated E1 proteins.