The host-cell architectural protein HMG I(Y) modulates binding of herpes simplex virus type 1 ICP4 to its cognate promoter

The productive infection cycle of herpes simplex virus is controlled in par t by the action of ICP4, an immediate-early gene product that acts as both an activator and repressor of transcription. ICP4 is autoregulatory, and IE -3, the gene that encodes it, contains a high-affinity binding site for the protein at its cap site. Previously, we had demonstrated that this site co uld be occupied by proteins found in nuclear extracts from uninfected cells . A HeLa cell cDNA expression library was screened with a DNA probe contain ing the IE-3 gene cap site, and clones expressing the architectural chromat in proteins HMG 1 and HMG Y were identified by this technique. HMG I is sho wn to augment binding of ICP4 to its cognate site in in vitro assays and to enhance the activity of this protein in short-term transient expression as says. (C) 1999 Academic Press.