Initiation of new DNA strands by the herpes simplex virus-1 primase-helicase complex and either herpes DNA polymerase or human DNA polymerase alpha.
A key set of reactions for the initiation of new DNA strands during herpes simplex virus-1 replication consists of the primase-catalyzed synthesis of short RNA primers followed by polymerase-catalyzed DNA synthesis (i.e. primase-coupled polymerase activity). Herpes primase (UL5-UL52-UL8) synthesizes products from 2 to approximately 13 nucleotides long. However, the herpes polymerase (UL30 or UL30-UL42) only elongates those at least 8 nucleotides long. Surprisingly, coupled activity was remarkably inefficient, even considering only those primers at least 8 nucleotides long, and herpes polymerase typically elongated <2% of the primase-synthesized primers. Of those primers elongated, only 4-26% of the primers were passed directly from the primase to the polymerase (UL30-UL42) without dissociating into solution. Comparing RNA primer-templates and DNA primer-templates of identical sequence showed that herpes polymerase greatly preferred to elongate the DNA primer by 650-26,000-fold, thus accounting for the extremely low efficiency with which herpes polymerase elongated primase-synthesized primers. Curiously, one of the DNA polymerases of the host cell, polymerase alpha (p70-p180 or p49-p58-p70-p180 complex), extended herpes primase-synthesized RNA primers much more efficiently than the viral polymerase, raising the possibility that the viral polymerase may not be the only one involved in herpes DNA replication.
Cavanaugh
Nisha A
NA
Department of Chemistry and Biochemistry, University of Colorado, Boulder, Colorado 80309-0215, USA.
Kuchta
Robert D
RD
D004265:DNA Helicases / Q000378:metabolism*; D004256:DNA Polymerase I / Q000378:metabolism*; D019915:DNA Primase / Q000378:metabolism*; D017931:DNA Primers / Q000378:metabolism; D004279:DNA, Viral / Q000096:biosynthesis*; D004259:DNA-Directed DNA Polymerase / Q000378:metabolism*; D005090:Exodeoxyribonucleases / Q000378:metabolism*; D018259:Herpesvirus 1, Human / Q000502:physiology*; D006801:Humans; D012313:RNA / Q000378:metabolism; D014764:Viral Proteins / Q000378:metabolism*; D014779:Virus Replication / Q000502:physiology*
D017931:DNA Primers; D004279:DNA, Viral; C034477:RNA primers; D014764:Viral Proteins; D012313:RNA; D019915:DNA Primase; D004256:DNA Polymerase I; D004259:DNA-Directed DNA Polymerase; D005090:Exodeoxyribonucleases; C062021:helicase-primase, Human herpesvirus 1; C043417:DNA polymerase, Simplexvirus; D004265:DNA Helicases