Overlapping positive and negative regulatory domains of the human beta-interferon gene.

Virus or poly(I).poly(C) induction of human beta-interferon gene expression requires a 40-base-pair DNA sequence designated the interferon gene regulatory element (IRE). Previous studies have shown that the IRE contains both positive and negative regulatory DNA sequences. To localize these sequences and study their interactions, we have examined the effects of a large number of single-base mutations within the IRE on beta-interferon gene regulation. We find that the IRE consists of two genetically separable positive regulatory domains and an overlapping negative control sequence. We propose that the beta-interferon gene is switched off in uninduced cells by a repressor that blocks the interaction between one of the two positive regulatory sequences and a specific transcription factor. Induction would then lead to inactivation or displacement of the repressor and binding of transcription factors to both positive regulatory domains.