Herpes simplex virus type 1 polypeptide ICP4 bends DNA.

ICP4, the major regulatory polypeptide of herpes simplex virus type 1, is expressed at the earliest stages of virus infection and is required for the activation of transcription from the majority of viral promoters. It is a DNA binding protein which specifically recognises bipartite sites related to the sequence ATCGTnnnnnCGG. In this report we show that both partially purified ICP4, and its isolated DNA binding domain, bend DNA at occupied binding sites. The apparent angles of bend at two different binding sites were very similar and in both cases the centre of the bend was very close to the binding site sequence.