REPRESSION OF A HERPES-SIMPLEX VIRUS IMMEDIATE-EARLY PROMOTER BY THE OCT-2 TRANSCRIPTION FACTOR IS DEPENDENT ON AN INHIBITORY REGION AT THEN-TERMINUS OF THE PROTEIN

The B-cell form of the Oct-2 transcription factor Oct 2.1 can activate the herpes simplex virus immediate-early gene 3 (IE3) promoter, where as the neuronally expressed Oct 2.4 and 2.5 forms of the protein, whic h contain a different C terminus, can repress this promoter. Here we s how that partial or full deletion of the C terminus of Oct 2.1 in the presence of an intact N terminus results in a protein which can strong ly repress the IE3 promoter. In contrast, deletion of the entire N ter minus or a short region within it leaving the C terminus intact result s in a very strong activator. Deletion of both N and C termini leaving only the isolated POU domain generates only a very weak repressor. Th e N-terminal region defined in this way can repress a heterologous pro moter when linked to the DNA-binding domain of the GALA factor, indica ting that it can function as an independent inhibitory domain. These r esults indicate that a specific region within the N terminus common to Oct 2.1, 2.4, and 2.5 plays a critical role in the ability of neurona lly expressed forms of Oct-2 to repress the IE3 promoter but can do so only when the C-terminal region of Oct 2.1 is altered or deleted.