The origin-binding domain of the herpes simplex virus type 1 UL9 protein is not required for DNA helicase activity.
The UL9 protein of herpes simplex virus type 1 binds to specific sequences within the viral origins of DNA replication and also functions as a DNA helicase. The C-terminal 317 amino acids of the 851 residue protein specify sequence-specific binding to the viral origins and the N-terminal 400 contain several motifs characteristic of many DNA and RNA helicases. To investigate whether the origin-binding domain is required for helicase function we have expressed a truncated version comprising amino acids 1-535 of UL9 using a recombinant baculovirus. Extracts were prepared from cells infected with the recombinant virus and chromatographed over ATP-agarose. DNA helicase, DNA-dependent ATPase and a novel single-stranded DNA-binding activity were present in fractions containing the truncated UL9 protein but not in corresponding gradient fractions from a control virus infection. These results indicate that the DNA helicase function of UL9 does not require the presence of the origin-binding domain and suggest that an interaction between the N-terminal domain and distorted or partially single-stranded regions of DNA may play a role in unwinding the origin region.
Abbotts
A P
AP
MRC Virology Unit, Institute of Virology, Glasgow, UK.
Stow
N D
ND
D000251:Adenosine Triphosphatases / Q000378:metabolism; D000255:Adenosine Triphosphate / Q000378:metabolism; D000818:Animals; D016367:Baculoviridae / Q000235:genetics; D002457:Cell Extracts; D002460:Cell Line; D004265:DNA Helicases / Q000235:genetics / Q000378:metabolism*; D004277:DNA, Single-Stranded / Q000378:metabolism; D004279:DNA, Viral / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D005814:Genes, Viral / Q000235:genetics; D018259:Herpesvirus 1, Human / Q000201:enzymology* / Q000235:genetics; D018741:Replication Origin; D018411:Spodoptera; D014764:Viral Proteins / Q000235:genetics / Q000378:metabolism*
D002457:Cell Extracts; D004277:DNA, Single-Stranded; D004279:DNA, Viral; D004268:DNA-Binding Proteins; D014764:Viral Proteins; C064565:UL9 protein, Human herpesvirus 1; D000255:Adenosine Triphosphate; D000251:Adenosine Triphosphatases; D004265:DNA Helicases