The herpes simplex virus type 1 origin-binding protein - Sequence-specificactivation of adenosine triphosphatase activity by a double-stranded DNA containing box I

Origin-dependent replication of the herpes simplex virus type 1 genome requ ires the virally encoded origin-binding protein, UL9. UL9 binds specificall y to the herpes simplex virus type 1 replication origin at two high affinit y binding sites on the DNA, Boxes I and II. UL9 also has ATP-dependent DNA helicase and DNA-stimulated ATPase activities that are used to unwind the o rigin DNA. Origin-specific binding is mediated by the C-terminal domain (C- domain) of the enzyme. ATPase and helicase activities are mediated by the N -terminal domain (N-domain). Previous studies have shown that single-strand ed DNA is a good coeffector for ATPase activity. We have analyzed several D NAs for their ability to stimulate the ATPase activity of UL9 and of a trun cated UL9 protein (UL9/N) consisting only of the N-domain. We report here t hat duplex Box I DNA specifically and potently stimulates the ATPase activi ty of UL9 but not of UL9/N. We also find that removal of the C-domain signi ficantly increases the ATPase activity of UL9. We have incorporated these r esults into a model for initiation in which the C-domain of UL9 serves to r egulate the enzymatic activity of the N-domain.