Coordination of leading and lagging strand DNA synthesis at the replication fork of bacteriophage T7.
We have used the T7 DNA replication system to examine coordination of leading and lagging strand synthesis at a replication fork. The 63 kd gene 4 protein provides both helicase and primase activities; we demonstrate that primer synthesis inhibits helicase activity on a synthetic replication fork. Lagging strand DNA synthesis by a complex of gene 4 protein and T7 DNA polymerase decreases the rate of leading strand synthesis. Both leading and lagging strand synthesis are resistant to dilution of the replication proteins, and to challenge with heparin. Furthermore, dilution does not increase the average length of Okazaki fragments. We propose that leading and lagging strand synthesis at a T7 replication fork are coupled and that the replication proteins are recycled.
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Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, Massachusetts 02115.
Tabor
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Richardson
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D000255:Adenosine Triphosphate / Q000378:metabolism; D017123:Bacteriophage T7 / Q000235:genetics*; D001483:Base Sequence; D003570:Cytidine Triphosphate / Q000378:metabolism; D004265:DNA Helicases / Q000378:metabolism*; D019915:DNA Primase; D004261:DNA Replication; D004277:DNA, Single-Stranded / Q000378:metabolism; D004279:DNA, Viral / Q000378:metabolism; D004259:DNA-Directed DNA Polymerase / Q000378:metabolism*; D008969:Molecular Sequence Data; D012316:RNA Nucleotidyltransferases / Q000378:metabolism
D004277:DNA, Single-Stranded; D004279:DNA, Viral; D003570:Cytidine Triphosphate; D000255:Adenosine Triphosphate; D019915:DNA Primase; D012316:RNA Nucleotidyltransferases; C034970:bacteriophage T7 induced DNA polymerase; D004259:DNA-Directed DNA Polymerase; D004265:DNA Helicases