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 fagging strand synthesis are resistant to dilution of the replication proteins, and to challenge with heparin. Furthermore, dilution does trot 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.