The herpes simplex virus type I origin binding protein. DNA-dependent nucleoside triphosphatase activity.
A recombinant baculovirus overexpressing the herpes simplex virus type 1 (HSV-1) origin binding protein, encoded by the UL9 gene, was constructed. The purified recombinant protein has DNA-dependent nucleoside triphosphatase activity similar to the enzyme isolated from mammalian cells. Optimal nucleoside triphosphatase activity requires low salt (< 50 mM), 2-3 mM Mg2+, alkaline pH (8.3-9.5), high temperature (45 degrees C), and a single-stranded DNA coeffector containing minimal secondary structure. Enzymatic activity is subject to product inhibition, and there appears to be a single nucleotide binding site. The minimal length of single-stranded DNA that elicits enzymatic activity is 14 nucleotides, and activity increases as the length is increased. Saturation for various single-stranded DNA coeffectors is about 10 microM in nucleotide, but the maximum velocity is reduced 2-3-fold for coeffectors containing secondary structure. The HSV-1-encoded single-stranded DNA-binding protein ICP8 specifically stimulates the DNA-dependent nucleoside triphosphatase activity. The kinetics of nucleoside triphosphate hydrolysis exhibit a substantial lag period which can be shortened, but not eliminated, by reduced secondary structure in the DNA coeffector or by increased temperature.
Dodson
M S
MS
Department of Biochemistry, Beckman Center, Stanford University School of Medicine, California 94305-5307.
Lehman
I R
IR
D000251:Adenosine Triphosphatases / Q000235:genetics / Q000378:metabolism*; D000818:Animals; D016367:Baculoviridae / Q000235:genetics; D002460:Cell Line; D004265:DNA Helicases; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D005814:Genes, Viral; D006863:Hydrogen-Ion Concentration; D007313:Insecta; D007700:Kinetics; D008274:Magnesium / Q000494:pharmacology; D011994:Recombinant Proteins / Q000378:metabolism; D012265:Ribonucleotides / Q000378:metabolism; D018139:Simplexvirus / Q000201:enzymology* / Q000235:genetics; D013379:Substrate Specificity; D013816:Thermodynamics; D014162:Transfection; D014764:Viral Proteins / Q000235:genetics / Q000378:metabolism*
D004268:DNA-Binding Proteins; D011994:Recombinant Proteins; D012265:Ribonucleotides; D014764:Viral Proteins; C064565:UL9 protein, Human herpesvirus 1; D000251:Adenosine Triphosphatases; D004265:DNA Helicases; D008274:Magnesium