The octamer-binding proteins form multi-protein-DNA complexes with the HSV αTIF regulatory protein

Abstract

The herpes simples virus transactivator, αTIF, stimulates transcription of the α/immediate early genes via a cis-acting site containing an octamer element and a conserved flanking sequence. The αTIF protein, produced in a baculovirus expression system, nucleates the formation of at least two DNA-protein complexes on this regulatory element. Both of these complexes contain the ubiquitous Oct-1 protein, whose POU domain alone is sufficient to allow assembly of the αTIF-dependent complexes. A second member of the POU domain family, the lymphoid specific Oct-2 protein, can also be assembled into similar complexes at high concentrations of αTIF protein. These complexes contain at least two cellular proteins in addition to Oct-1. One of these protein is present in both insect and HeLa cells and probably recognizes sequences in the cis element. The second cellular protein, only present in HeLa cells, probably binds by protein-protein interactions.