THE CELLULAR TRANSCRIPTION FACTOR USF COOPERATES WITH VARICELLA-ZOSTER VIRUS IMMEDIATE-EARLY PROTEIN-62 TO SYMMETRICALLY ACTIVATE A BIDIRECTIONAL VIRAL PROMOTER

The mechanisms governing the function of cellular USF and herpesvirus immediate-early transcription factors are subjects of considerable int erest. In this regard, we identified a novel form of coordinate gene r egulation involving a cooperative interplay between cellular USF and t he varicella-zoster virus immediate-early protein 62 (IE 62). A single USF-binding site defines the potential level of IE 62-dependent activ ation of a bidirectional viral early promoter of the DNA polymerase an d major DNA-binding protein genes. We also report a dominant negative USF-2 mutant lacking the DNA-binding domain that permits the delineati on of the biological role of both USF-1 and USF-2 in this activation p rocess. The symmetrical stimulation of the bidirectional viral promote r by LE 62 is achieved at concentrations of USF-1 (43 kDa) or USF-2 (4 4 kDa) already existing in cells. Our observations support the notion that cellular USP can intervene in and possibly target promoters for a ctivation by a herpesvirus immediate-early protein.