FIG. 3.

Identification of the region of USF1 that is involved in mediating IE62 activation. (A) Schematic depiction of the USF1 fragments expressed via pQE-tri plasmid and the Gal4-USF fusion proteins with the DNA binding domain (DBD) of Gal4 fused with different fragments of the USF1 protein. (B) Examination of the effect of ectopic expression of the full-length and truncated USF1 proteins on IE62 activation of the VZV ORF28/29 regulatory element. One microgram pRFL/WT reporter vector and 0.02 μg pCMV62 plasmid were cotransfected with 0.5 μg each of the USF1-expressing plasmids and the control vector pQE-tri. The solid bars represent the promoter activities in the direction of ORF28, and the open bars represent that in the direction of ORF29. The endogenous USF1-mediated IE62 activation of the individual luciferase reporter genes in the presence of the empty pQE-tri plasmid was normalized to 100%. (C) Analysis of the Gal4-USF1 fusion proteins in mediation of IE62 activation of the pG1TALuc vector. One microgram pG1TALuc reporter vector and 0.02 μg pCMV62 plasmid were cotransfected with 0.5 μg each of the Gal4-USF1 fusion protein-expressing plasmids and the control vector pcDNA as indicated in the figure. Open and closed bars represent activity in the presence and absence of IE62, respectively. Luciferase assay data in panels B and C represent the averages of triplicate transfections. The error bars represent standard deviations. *, P < 0.05.