Unwinding of a Herpes Simplex Virus Type 1 Origin of Replication (Ori S ) by a Complex of the Viral Origin Binding Protein and the Single-Stranded DNA Binding Protein

Abstract

ABSTRACT A herpes simplex virus type 1 (HSV-1) Ori S analogue in which the A+T sequence linking the box I and II elements was replaced by two single-stranded oligo(dT)s is unwound by the UL9 protein-ICP8 complex. Unwinding of wild-type Ori S by the UL9 protein-ICP8 complex was also observed under conditions which destabilize the A+T sequence. These experiments support a model for the unwinding of Ori S in which destabilization of the A+T sequence can generate a single-stranded DNA binding site for ICP8, which then associates with the UL9 protein bound to boxes I and II to promote the bidirectional unwinding of Ori S .